SR 11-27-2018 8C
City Council
Report
City Council Meeting: November 27, 2018
Agenda Item: 8.C
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To: Mayor and City Council
From: Susan Cline, Director, Public Works, Water Resources
Subject: Sustainable Water Master Plan Update and Pathway to Water Self -
Sufficiency
Recommended Action
Staff recommends that the City Council:
1. Provide staff with direction to proceed with water self-sufficiency components.
2. Provide staff with direction regarding funding recommendations to achieve water
self-sufficiency.
3. Authorize budget changes as outlined in the Financial Impacts and Budget
Actions section of this report.
4. Direct staff to return for a public hearing on January 8, 2019, to consider
implementation of 9% water rate increase previously approved by Council on
February 24, 2015 to go into effect on March 1, 2019.
Executive Summary
The City of Santa Monica (City) has historically provided water service to residential and
business customers allowing for bold efforts in securing resiliency and self -sufficiency
for the community. Given the statewide challenges surrounding a safe and reliable
water supply in recent years, Council directed staff to develop a water self -sufficiency
plan with the goal of meeting 100% of Santa Monica’s water demand using local water
sources by 2020. On October 28, 2014, Council adopted the Sustainable Water Master
Plan (SWMP), which outlines a strategy to achieve the City’s water self -sufficiency goal
(Attachment A). Staff initiated a comprehensive update of the SWMP in 2017 to
incorporate new information regarding local groundwater resources and to integrate
new water conservation programs and alternative water supply opportunities. On
January 9, 2018, staff reported to Council that further analysis was needed to assess
whether the City could meet its water self -sufficiency goal by 2020 (Attachment B). The
further analyses have been completed and confirm that achieving water self -sufficiency
that can be maintained into the future is practical and cost effective, but the projected
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date of reaching that goal would be 2023. The delay from the original date is due to new
state drinking water requirements implemented in 2018, permitting requirements for
alternative water supply projects, and results of recently completed feasibility studies
which resulted in longer timelines for project completion relative to previous estimates.
The benefits of becoming water self-sufficient when compared to the alternative of
continuing to meet a portion of local water demand using imported water include: long -
term cost benefits for water ratepayers, establishment of a diverse, sustainable and
drought resilient local water supply, and reduction of the City’s water supply energy
footprint. It should be noted that in the updated plan proposed by staff, water self -
sufficiency equates to approximately 99% locally sourced water, with 1% of the City’s
water supply still being purchased from the Metropolitan Water District of Southern
California (MWD) to maintain the imported water connection for emergency purposes.
The updated proposal to meet water self-sufficiency presented in this staff report
includes an optimized water conservation program together with local water supply
projects, an updated implementation timeline, and recommended funding toward
achieving water self-sufficiency for the City. Following Council direction and approval,
the final components will be included in an updated SWMP that will guide City efforts
toward achieving the goal through 2023. To achieve self -sufficiency by 2023, staff is
proposing to replace imported water purchases with a comprehensive plan consisting
of:
Component 1 - continuing and increasing water conservation efforts to
permanently reduce water demand,
Component 2 - developing sustainable and drought resilient alternative water
supplies, and
Component 3 - expanding local groundwater production within sustainable yield
limits.
The anticipated cost to implement the components required to meet the self -sufficiency
goal is approximately $38 million to increase local water supplies, which includes
capacity expansion of the Arcadia Water Treatment Plant (WTP), implementation of
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production efficiency enhancements, as well as acquiring an additional groundwater
well to enhance resiliency. The $38 million would be funded primarily through the
issuance of a water revenue bond and a contribution from the Wastewater Fund ($3.25
million) to the Water Fund to fund the various projects outlined in this staff report, with
the debt service on the bonds incorporated into water rates in an upcoming rate study.
An additional $64 million from existing water-contamination settlement funds would be
used for restoring the Olympic Sub-basin, which would allow additional water production
from that sub-basin to support achievement of water self -sufficiency. The proposed
water self-sufficiency plan and staff recommendations are based on recently completed
studies (e.g., confirmation of sustainable yield analysis, evaluation of new drinking water
regulations on the Olympic Sub-basin restoration, and feasibility studies to assess new
technologies that increase production efficiency at the Arcadia WTP) in which multiple
scenarios were evaluated for cost, benefits and effectiveness.
Lastly, staff will return to Council on January 8, 2019, for a public hearing and to
recommend a full implementation of the 9% water rate adjustment (within the previously
adopted Council authorization) for calendar year 2019 and effective on water bills
issued on or about March 1, 2019. The recommended water rate adjustment would
ensure a fiscally sustainable comprehensive program for safe, clean, reliable water
supply to our community. It would also help offset increased construction costs to keep
up with the City’s 100-year water main replacement program and fund preliminary
design efforts on the various components required to achieve water self -sufficiency as
contemplated in the 2014 rate study.
Background
On January 25, 2011, City Council directed staff to develop a water self -sufficiency plan
with the goal of meeting 100% of Santa Monica’s water demand using local water
sources by 2020. On October 28, 2014, Council adopted the SWMP which outlines a
comprehensive plan to achieve water self-sufficiency. The SWMP involves a
combination of water demand reduction strategies through various water conservation
and efficiency programs designed to permanently reduce residential and commercial
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water use, along with increased water supply from 1) alternative water sources such as
captured rainwater and treated wastewater; 2) increased efficiency of the City’s water
treatment systems; and 3) additional pumping from existing groun dwater wells and new
wells in the local groundwater basin. Implementation of the SWMP has been proceeding
since 2014, with updates provided during Council’s annual consideration of water rate
adjustments. The most recent update was provided on January 9, 2 018.
Between 2014 and 2018, other elements of the SWMP progressed, including
completion of a preliminary Sustainable Yield Analysis (SYA) of the Santa Monica
groundwater basin and finalizing plans for the Sustainable Water Infrastructure Project
(SWIP) to support further analysis and refinement of alternatives to reduce reliance on
imported water supply and meet the City’s self-sufficiency goal. Staff initiated a
comprehensive update of the SWMP in 2017 to incorporate new information regarding
local groundwater resources, regulatory updates, and to integrate new water
conservation programs and alternate water supply opportunities.
On January 9, 2018, staff reported to Council that further analysis was needed to
assess whether the City could meet its water self-sufficiency goal by 2020. Additional
work completed since January 2018 included analysis to validate preliminary SYA
estimates of the local groundwater basin, drilling of exploratory water wells in the
Coastal sub-basin to evaluate potential new local water production, technical studies to
evaluate the cost and viability of increasing the production efficiency of the City’s
Arcadia WTP, evaluating the impact of new drinking water regulations (e.g., maximum
contaminant level [MCL] for 1,2,3 TCP) on groundwater extraction from the Olympic
Sub-basin, and evaluating the cost and viability of additional water conservation
programs as requested by the Task Force on the Environment. A timeline summarizing
key events related to the development of the SWMP from 2011 is provided in Figure 1.
Staff currently anticipates that the City would achieve water self -sufficiency in 2023
based on the plan outlined in this report. In addition to the proposed plan to achieve
water self-sufficiency, a Five-Year Rate Study (2020-2024) is also currently underway
and will consider potential rate impacts of water self-sufficiency projects. Results of the
Five Year Rate Study will be presented to Council in the first half of 2019.
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January 25, 2011
City Council directed
staff to develop water
self-sufficiency plan
(100% on local water
supplies)
Council adopts Sustainable
Water Master Plan (Oct ’14)
Plan outlines the City’s strategy to
achieve water self-sufficiency
Olympic Treatment Pilot Project
Initiated (Sept ’14)
Evaluate treatment technologies to
restore pumping capacity at Olympic
Sub Basin
SWMP Update
(Nov ‘18)
Staff to present
strategy to meet
City’s water self-
sufficiency goal
Conservation Plan
Implemented (2015)
Increased conservation
efforts saw a ~20% reduction
in gallon per capita per day
(gpcd) water consumption
SWMP Update
(Jan ‘18)
Staff reported to City
Council that additional
analysis was needed to
determine if self-
sufficiency goal could
be met by 2020
New Contaminant at
Olympic Sub Basin
(May ‘18)
New drinking water
regulations required
additional analysis of
Olympic Sub Basin
treatment strategy
Water Self-
Sufficiency
Achieved (2023)
Figure 1: Self-Sufficiency Timeline
Discussion
Goals and Benefits of Water Self-Sufficiency
The proposed plan to meet the City’s self-sufficiency goal involves a combination of
demand reduction through various water conservation and efficiency programs and the
addition of local water supplies which will also provide the following benefits:
Long-term cost benefits to ratepayers by maximizing local water resources
Provide a more sustainable and drought-resilient water supply through a diversified
water supply portfolio
Reduce the City’s water supply energy footprint through conservation and locally
sourced water supplies
With imported water purchase costs from MWD expected to increase annually from 3 to
7 percent over the next 10 years, the primary focus of the updated SWMP was to
develop water self-sufficiency scenarios that are both sustainable and economical
compared to the continued purchase of imported water from MWD. Development of
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cost-effective local, sustainable, and drought resilient water supplies will provide Santa
Monica water ratepayers with cost benefits over the long-term and provide the City with
greater cost certainty on water rates compared to the continued purchase of imported
water from MWD.
Providing a sustainable and drought-resilient water supply through a diversified water
supply portfolio eliminates the City’s reliance on the purchase of imported water from
MWD and maintains reliable production during routine maintenance and unforeseen
downtimes of treatment equipment.
Lastly, maximizing local water resources instead of purch asing imported water from
MWD also has long-term environmental benefits for the community in terms of reduced
energy use and the associated reduction in greenhouse gas emissions, which support
Council’s goal to achieve carbon neutrality by 2050 or sooner. The addition of
alternative water supplies, expansion of local groundwater supplies, and increased
conservation will result in a 25-30% reduction of total energy footprint from the City’s
water supply compared to continued purchase of imported water from MWD.
Marching Toward Water Self-Sufficiency
The City’s water supply portfolio has progressively transformed since 2011, with the
community making significant strides toward water self-sufficiency and reduced reliance
on the purchase of imported water to supplement local water resources as indicated in
Figure 2. In 2011, after completion of the Charnock Wellfield Restoration Project, the
City was able to meet approximately 51 percent (~6,700 acre -feet per year [AFY]) of its
water supply demand through local groundwater resources and reduce the purchase of
water from MWD, which is imported from Northern California and the Colorado River, to
approximately 48% (~6,400 AFY).
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Figure 2: Overview of City’s Water Supply Portfolio from 2011 through 2017
In 2015, the City and its residents responded to severe drought conditions throughout
California with conservation efforts that resulted in a decrease in the City’s total water
demand of 14,300 AFY in 2014 by about 17% (-2,500 AFY) to approximately 11,800
AFY by 2017. Santa Monica’s population grew by about 1.6% from 92,321 to 93,834
over the same period. Conservation efforts resulted in a decrease in average annual
water consumption, measured in gallons per capita per day (GPCD), from 140 GPCD to
approximately 110 GPCD as indicated in Figure 3 and continues today even after the
governor declared an end to the drought.
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Figure 3: Historical Population Growth versus Per Capita Water Consumption
From 2015 through 2017, the City was meeting approximately 50-56% of its water
supply demand through local water sources (7,400-8,200 AFY) and 26-29% through
water conservation (approximately 2,500 AFY), with the amount of imported water
purchased from MWD dropping to approximately 26 -29% (3,700-4,100 AFY). In 2017,
local groundwater supply temporarily decreased due to an extended shutdown
(approximately six months) of one well in the Charnock sub -basin for maintenance and
repair. The loss of a single well from the Charnock Sub-basin over the six-month period
and loss of approximately 800 AFY of groundwater production highlighted the need to
increase resiliency of the local water supply to maintain reliable production as the City
continues its march toward water self-sufficiency.
Refined SWMP Pathway to Achieve Water Self-Sufficiency
Additional analyses of various elements of the SWMP, as outlined at the January 9,
2018 City Council meeting, have been completed, and based on those analyses staff
now estimates that water self -sufficiency can be achieved by 2023. To achieve self-
sufficiency by 2023, staff is proposing to replace the purchase of imported water from
MWD (approximately 50% of the total water supply demand when self -sufficiency efforts
were initiated in 2011) with a comprehensive plan consisting of: 1) Component 1 -
continuing and increasing water conservation efforts to permanently reduce water
demand, 2) Component 2 - developing sustainable and drought resilient alternative
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water supplies, and 3) Component 3 - expanding local groundwater production within
sustainable yield limits.
The delay in achieving the City’s self-sufficiency goal from 2020 to 2023 is due to
several factors, including new regulations established by the State Water Resources
Control Board’s Division of Drinking Water (DDW) that required further analysis to
determine the level of treatment required for the Olympic Sub -basin, the project timeline
and permitting schedule for the SWIP project to recharge local groundwater aquifers
with purified water, and the need to confirm and refine preliminary SYA estimates with
additional data to establish an accurate estimate of the sustainable yield for the Santa
Monica Groundwater Basin.
The remainder of this staff report is organized as follows to provide detailed descriptions
of each component of the updated SWMP and its contribution/benefits toward the City’s
self-sufficiency goal:
Proposed Plan to Achieve Water Self-Sufficiency
SWMP Project Cost and Implementation Schedule
Funding Recommendations
Proposed Plan to Achieve Water Self-Sufficiency
A comprehensive plan was developed through the SWMP and comprises three
components that provide a path for the City to achieve water self -sufficiency by 2023.
The contribution of each proposed component to eliminate reliance on imported water
supply by 2023 is summarized in Figure 4 along with the percent contribution toward
replacing imported water purchases. In total, the three components: 1) conservation, 2)
alternative water supplies - production efficiency, recycled water, and purified water for
recharge, and 3) new local groundwater will contribute approximately 8,057 AFY toward
the City’s total water supply and reduce imported water purchase to only 170 AFY. A
brief description of each of the recommended components is provided below.
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New Local Groundwater,
2,100 AFY, 25%
Imported
Water (MWD),
170 AFY, 2%
Alternative Water Supply -
Purified Water (Recharge),
1,100 AFY
Alternative Water Supply -
Recycled Water , 560 AFYAlternative Water Supply
-Production Efficiency,
1,200 AFY
Conservation, 3,097 AFY, 38%
PROPOSED STRATEGIES TO REPLACE IMPORTED WATER SUPPLY (2023)
New Local Groundwater Imported Water (MWD)
Alternative Water Supply - Purified Water (Recharge)Alternative Water Supply - Recycled Water
Alternative Water Supply - Production Efficiency Conservation
Alternative Water Supply,
2,860 AFY, 35%
Figure 4: Summary of Proposed Components to Replace Imported Water Supply by 2023
Component 1 - Conservation (38% Reduction in Imported Water Purchases)
In 2014, Council authorized the significant expansion of staffing and funding to augment
the City’s water conservation efforts to address the state-wide drought and help the City
meet its self-sufficiency goal. This contributed to a water demand reduction of
approximately 20% over the past three years (2015 -2017), which equates to saving
approximately 2,500 AFY. Continued implementation of the existing conservation
programs with the addition of supplemental conservation efforts is expected to continue
this trend of water demand reduction through 2040, with the staff recommended Optimal
conservation plan which is described below. Continuation of existing, and
implementation of proposed, conservation programs are essential for the City to
eliminate reliance on imported water from MWD. The recommended Optimal
conservation plan will contribute approximately 3,100 AFY to the City’s water
supply portfolio in 2023 and reduce imported water purchases by roughly 38%.
Staff modeled three conservation plans (Optimal, Enhanced, and 90 GPCD), which are
presented in gallons per capita per day by 2025 and abbreviated as GPCD. The
Optimal Conservation Plan can be completed using existing budgeted resources and
would reduce the City’s total water demand by approximately 20%, even after factoring
in demand increases associated with expected population growth through 2025.
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Increasing conservation efforts from the Optimal to the Enhanced Plan would cost an
additional $7.2 million in total program cost, on top of the budget already allocated for
the Optimal Conservation Plan, but with a marginal increase in water conserved
(approximately 2% additional reduction in GPCD with the Enhanced Plan). The
enhanced conservation plan would still require approximately 3,500 to 3,700 AFY of
water that would need to be met through the purchase of imported water or from the
development of additional local water resources. With marginal gains from increased
conservation efforts compared to the additional implementation cost required, staff is
recommending continuing with the optimal conservation plan, which costs
approximately $708/AF of water saved.
A third, aggressive conservation plan was also studied following a request by the Task
Force on the Environment to evaluate the cost and feasibility of reducing city -wide water
demand to 90 GPCD by 2025. The assessment of the 90 GPCD Plan conducted by
staff concluded that reducing overall water demand to 90 GPCD would be extremely
costly and may not be feasible for implementation. The overall cost to implement this
plan would exceed $56.6 million, with $40 million of the cost incurred over the first five
years. In addition to the significant cost premium, this scenario would likely require
additional staffing and would be very challenging to achieve by 2025.
Staff met with industry experts to review and receive input on the City staff modeling of
proposed conservation programs. A panel of outside experts supported both the optimal
and enhanced conservation plans and the proposed programs that comprise them. A
summary of the conservation scenarios evaluated is provided in Table 1.
Table 1: Summary of Conservation Scenarios Considered
Description1 Conclusion Cost
Optimal,
108 GPCD
Best Conservation option
Does not achieve self-sufficiency
goal by itself but supports demand
reduction.
Within current operating budget
$708/AF (over 30 years) 2
Enhanced,
106 GPCD
Feasible but expensive compared to
Optimal Plan. Requires 1.5 new
staff for 10 years
$7.2 million increase in program
costs compared to Optimal
(2018-2023)
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Does not achieve self-sufficiency
goal
Not worth the incremental cost for a
2GPCD reduction.
137% increase in budgeted costs
(2018-2013)
$1,078/AF (over 30 years) 2
Aggressive,
90 GPCD
Potentially feasible but very
expensive, requires 2.5+ new staff
for 10 years
Does not achieve self-sufficiency
goal
$40.8M over the first five years;
$58.6 M 2019-2040,
800% increase in costs (2018-
2023) compared to Optimal
Scenario
~$1,280/AF (over 30 years)2
1GPCD based on water conservation efforts achieved as of 2025
2Excluding ongoing conservation staffing cost.
Due to conservation efforts since 2015, the City’s current water demand measured in
gallons per capita per day (GPCD) is approximately 110 GPCD. Staff also conducted a
theoretical exercise to determine what would be required for the City to become water
self-sufficient solely through conservation efforts (assuming no imported water and no
additional local water production). Results of that exercise indicated that the total per
capita water demand would need to be reduced to 64 GPCD. Staff consulted water
conservation experts, analyzed conservation efforts in other cities and evaluated
various local conservation scenarios and determined that attempting to achieve the self -
sufficiency goal through conservation alone (i.e. achieving 64 GPCD in Santa Monica) is
neither financially feasible nor realistic within the time horizon.
However, the community should be commended on the conservation efforts already
taken to reduce water demand and decrease imported water purchased from MWD.
Santa Monica is - and can be - a model for a new ethic of resource self-sufficiency and
environmental sustainability. The Council’s recent adoption of the 100% renewable
default rate for community electric supply represents this ethos of “living within our
means.” Conservation will continue to play a critical role in the City’s march toward
water self-sufficiency by continuing to reduce overall water demand in the face of
continued population growth from new housing and demand from the commercial and
institutional sectors of our local economy.
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Based on the modeling described above, staff recommends pursuing the Optimal
conservation plan, which continues the successful conservation programs initiated over
the past three years and increases water conservation in untapped areas such as:
Funding of retrofits in Santa Monica-Malibu Unified School District facilities and
landscapes
Commercial sector fixture retrofits and enhanced rebates
Coin-operated laundry machine retrofits
Increase in Water Neutrality offsets and direct installs
Rebates for new technologies including gray and black water systems
Enhanced water conservation education and enforcement
Additional sustainable landscape conversions
Outreach to assist customers on how to properly adjust their irrigation timers
New marketing and outreach campaign focusing on instilling permanent
conservation behaviors consistent with the state’s forthcoming framework for
“Making Water Conservation a California Way of Life”
Incorporating limited-term employees as part of the permanent water conservation
team to ensure new state requirements and regulations are met, as well as
maintaining programs at an effective level
In developing the water conservation plan to reach and maintain self-sufficiency, the
City evaluated the potential for further water efficiency and conservation in all customer
sectors. This included an assessment of the current level of water fixtures in the city, as
well as identifying where the greatest opportunity for reducing water consumption
existed. Based on this analysis, a program plan was developed to reach the City’s long-
term objectives via existing and new conservation programs.
Table 2 shows the projects planned over the next five years including the number of
activities for each program such as number of rebates, consultations and direct
installation of water efficient fixtures to replace inefficient fixtures in existing buildings
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throughout the city. The projected number of activities is based on historical
participation, available market of opportunity, and strategic community engagement
campaigns to increase programs over multi-year periods. The table also includes the
estimated water savings and total costs from 2018 through 2023 when water self -
sufficiency is expected to be reached.
Table 2: Summary of Optimal Water Conservation Programs and Results
Measure Customer Class Total Activities
2018-2023
Total Water Savings (AF)
2018-2023
Rebates, Single Family
(i.e. clothes washers, landscape, soil sensors, toilets, irrigation)Single Family 4,660 286
Water Use Consultations, Single Family Single Family 720 58
Graywater System Incentive Single Family 60 1
Direct Installs, Single Family
(i.e. 0.80 gpf toilets, water neutrality) Single Family 0 0
Direct Installs, Multi-Family
(0.80 gpf and 1.06 or less gpf toilets)Multi-Family 3,750 124
Rebates, Multi-Family
(i.e. high-efficiency clothes washers, landscape, toilets)Multi-Family 1,475 94
Water Use Consultations, Multi-Family Multi-Family 750 90
School Education Program Institutional 2,090 14
Direct Installs, Santa Monica Malibu Unified School District
(i.e. 0.80 gpf and 0.125 gpf toilets and urinals, water neutrality) Institutional 537 9
Santa Monica Malibu Unified School District Weather Based
Irrigation Controller Incentive Institutional 22 21
Santa Monica Malibu Unified School District Landscape
Incentive Institutional 9 8
Rebates, Commercial & Institutional
(i.e. ice machines, toilets, urinals, toilets, irrigation)Commercial & Institutional 1,792 260
Direct Installs, Commercial & Institutional
(i.e. toilets and urinals) Commercial & Institutional 3,280 517
Water Use Consultations, Commercial & Institutional Commercial & Institutional 300 45
Performance Pays Commercial & Institutional 4 9
Soil Moisture Sensor Rebates Multi-Family, Commercial &
Institutional 75 7
Water Saving Devices - Faucet Aerators All 9,240 328
Water Saving Devices - Showerheads All 4,200 160
Community Outreach & Education All 16 1
Pilot Projects All 2 2
32,982 2,034Total
The financial summary of the Optimal Conservation Plan is provided in Table 3.
Table 3: Financial Summary of Optimal Water Conservation Plan
Average Water Savings (AFY)
610
Cost of Savings per Unit Volume ($/AF)
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$708
Modeling of the water conservation plan was purposefully conservative and only
includes expected water demand reductions directly related to City efforts. Therefore,
the projected demand reductions do not include the potential savings from efficiency
improvements in California State Plumbing Codes known as “passive conservation.”
Passive water conservation is achievable through non -City sponsored programs, such
as maximizing current plumbing code enforcement, landscape ordinances, natural
fixture replacement rates, as well as future local and state regulations and codes. This
includes the impact and enforcement of the legislation, California SB 407, requiring
noncompliant plumbing fixtures in any single-family residential and multi-family
residential, and commercial properties to be replaced by the property owner with water-
conserving plumbing fixtures.
Through the currently established programs, proposed new programs, and passive
conservation, it is estimated that the City can reach 99 GPCD by 2025 and 96 GPCD by
2030. These efforts would result in an estimated additional annual savings between 680
acre-feet (AF) per year by 2025 and as much as 1,000 AF per year in 2030. The City
allocates funding for conservation within the water fund annual operating budget; no
additional funding would be required to implement the Optimal Conservation Plan. Staff
will return during the Five-Year Rate Study to present long-term staffing options for the
recommended Optimal Conservation Program.
Component 2 - Alternative Water Supplies (35% Reduction in Imported Water
Purchases)
To further diversify the City’s water supply portfolio and increase overall resilience ,
three alternative water supply projects are proposed and collectively offset
imported water purchases from MWD by 35 percent (see Figure 4). These projects
include:
Increase recycled water production through the Sustainable Water Infrastructure
Project (SWIP), upgrading the existing Santa Monica Urban Runoff Recycling
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Facility (SMURRF) and constructing a new Advanced Water Purification Facility
(AWPF) that provides a drought resilient, local water supply. The increase in
recycled water production from SMURRF would offset imported water purchases
from MWD by approximately 4% (approximately 560 AFY).
Recharge local groundwater aquifers in the Olympic Sub-basin to maintain
sustainable yield pumping levels with purified water from the SWIP’s AWPF. The
purified water from the AWPF would offset imported water purchases from MWD by
approximately 7% (approximately 1,100 AFY).
Upgrade the City’s Arcadia Water Treatment Plant (WTP) with new technology to
increase overall production. Closed Circuit Reverse Osmosis (CCRO) would be
added to the Arcadia WTP to treat the Reverse Osmosis concentrate waste stream,
which is currently discharged to the sewer system, and increase the overall
treatment efficiency at the Arcadia WTP to approximately 90 percent, or greater. The
addition of CCRO at the Arcadia WTP would offset imported water purchases from
MWD by approximately 8% (approximately 1,200 AFY).
The SWIP project is a major component of the alternative water supply for the City as it
will provide a sustainable and drought resilient water supply by providing purified water
to recharge local groundwater aquifers. In return, the aquifer recharge that will be
provided by the SWIP will allow the City to maximize groundwater pumping, within
sustainable yield limits, from the Olympic Sub-basin.
Component 3 - New Local Groundwater Production (25% Reduction in Imported
Water Purchases)
To offset the remaining imported water purchased from MWD, local groundwater
production would need to be increased to reduce imported water purchases from
MWD by 25% and resiliency measures implemented to maintain reliable production.
Staff developed and analyzed seven scenarios to expand the City’s groundwater
production and carefully vetted each scenario internally and with outside industry
experts. The seven scenarios were compared based on project feasibility, capital, and
operation cost, and are summarized in Attachment C. All scenarios evaluated assume
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that the Optimal Conservation Plan is implemented. Of the seven scenarios evaluated,
Scenario 1 - Expansion of Arcadia WTP with Closed Circuit Reverse Osmosis (CCRO)
combined with a Separate Olympic Sub-basin Pipeline and Treatment at the Arcadia
WTP site is recommended. Scenario 1 combined with the Optimal Conservation Plan is
the most cost-effective solution to achieve self-sufficiency and maximize local water
resources. Scenario 1 includes the following elements:
Expansion of the Arcadia WTP, including CCRO technology (as discussed under
component 2 - alternative water supplies), to increase treatment capacity and
accommodate future 2040 water demands.
Acquisition of a new groundwater well to enhance resiliency.
Olympic Sub-basin Restoration:
o A new pipeline separating Olympic Sub-basin water, conveying it independently
to the Arcadia WTP, thus requiring a smaller treatment facility at the Arcadia
WTP to remove contaminants in the Olympic Sub-basin.
o Separate contamination treatment facility at the Arcadia WTP for the Olympic
basin.
Expansion at Arcadia WTP
To support development of alternative water supplies and restoration of the Olympic
Sub-basin, treatment capacity expansion and plant upgrades are required at the
Arcadia WTP to support an overall increase in water production and enhance resiliency
to achieve water self-sufficiency. The Arcadia WTP is currently capable of treating up to
approximately 11,300 AFY (10 million gallons per day [mgd]) and produce 9,900 AFY
(8.9 mgd) of treated water (approximately 82% recovery or efficiency). The proposed
expansion and addition of new technologies to increase production efficiency at the
Arcadia WTP will increase its treatment capacity to approximately 14,700 AFY (13 mgd)
and produce 13,400 AFY (12 mgd) of treated water (approximately 92% recovery or
efficiency). The proposed improvements for expanding production capacity at the
Arcadia WTP and enhancing water supply resiliency include:
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Acquire an additional groundwater well to enhance resiliency and maintain
production during routine maintenance or unforeseen downtimes of groundwater
wells, while aggressively pumping within the sustainable yield.
Install new CCRO to increase overall plant efficiency to 90 percent or greater (as
discussed previously under component 2 - alternative water supplies).
Expand capacity (e.g., pumps, blowers, cartridge filters, etc.) of the Arcadia WTP to
accommodate increased groundwater production and new technologies (e.g., CCRO
described in Component 2).
Olympic Sub-basin Restoration
The Olympic Sub-basin plays a key role in achieving the City’s water self -sufficiency
goal as it could provide up to 3,200 AFY of groundwater and is also the location where
purified water from the SWIP will be recharged to sustain this pumping rate. However,
the Olympic Sub-basin contains several contaminants that would require additional
treatment to meet drinking water standards. The key contaminants in the Olympic Sub -
basin include: 1,2,3-Trichloropropane (1,2,3-TCP), 1,4-Dioxane, trichloroethylene
(TCE), and tetrachloroethylene (PCE). Drinking water regulations, or maximum
contaminant levels (MCL), have been in place for TCE and PCE prior to January 2018,
and regulations for 1,2,3- TCP were established after January 2018 which required
further treatment analysis. 1,4-Dioxane is currently on the State of California’s drinking
water Notification Level (NL) list, which is a health-based advisory level and not an
MCL. It is anticipated that the NL of 1 microgram per liter (g/L) or part per billion (ppb)
for 1,4-Dioxane will likely become an MCL in the near future (within next 5 years).
Further analysis of treatment options for the Olympic Sub -basin was required due to a
recently established drinking water regulation that established a MCL for 1,2,3 TCP at 5
parts per trillion (ppt), and additional data on 1,4 Dioxane was available to refine the
treatment analysis to determine if the current 1 ppb NL (anticipated future MCL) could
be met once full production of the Olympic Sub-basin is restored. The Olympic Sub-
basin treatment analysis was performed by an outside consultant, Black & Veatch. Key
findings of the treatment analysis are listed below:
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1,2,3-TCP was only detected at one well, SM-4, and the MCL of 5 ppt could be met
through blending with other wells at full production capacity.
1,4-Dioxane is present in all three wells (two existing and one future) and could limit
groundwater production from the Olympic Sub-basin to 845 AFY or approximately
25% of the basin’s total sustainable yield.
Other contaminants, TCE and PCE, do not impact groundwater production from the
Olympic Sub-basin as they would be removed through existing treatment processes
at the Arcadia WTP.
To maximize groundwater production from the Olympic Sub-basin and comply with
regulation on the key contaminants of concern, the following improvements are
recommended:
Increase groundwater pumping from existing wells (SM -3 and SM-4), complete
equipping and permitting of one recently installed new well (SM-8) and install a
replacement well (SM-9) to increase local production from this sub-basin to ~3,200
AFY within sustainable yield levels. Please note that purified water from the SWIP
will be used to recharge the Olympic Sub-basin that helps maintain the sustainable
yield levels by supplementing naturally available groundwater within the sub -basin.
Design and procurement efforts are currently underway, and the well projects were
previously approved by Council in the FY 19-20 Capital Improvement Budget.
Construct a new pipeline to separate Olympic Sub-basin groundwater from
Charnock wellfield groundwater for separate treatment at the Arcadia WTP, primarily
to target removal of 1,4 Dioxane. This reduces the amount of water needing
treatment since only the Olympic Sub-basin flows (3,200 AFY) contain 1,4 Dioxane.
If the flows are not separated, 14,700 AFY (Olympic + Charnock) would need to be
treated.
Construct a new contamination treatment facility for only the Olympic Sub -basin
flows to remove 1,4 Dioxane, 1,2,3-TCP, TCE, and PCE at the Arcadia WTP site.
The proposed treatment train consists of the ultraviolet light advanced oxidation
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process and granular activated carbon. With the new contamination treatment facility
and increased production efficiency (90-92% recovery) at the Arcadia WTP,
approximately 2,900 AFY of treated water will be produced from the 3,200 AFY
extracted from the Olympic Sub-basin. The new contamination treatment facility will
provide high-quality drinking water that meets current and future regulatory
standards.
Sustainable Yield Update
The sustainable yield from the Santa Monica Groundwater Basin is a critical component
to ensure overall groundwater production is within sustainable limits of the basin and
could support the proposed projects described above on an ongoing basis. A
preliminary Sustainable Yield Analysis, (SYA), prepared by Richard C. Slade &
Associates (Slade) in 2017, was presented to Council in January 2018. Since then,
additional work was performed to refine and update the SYA. Additional work included
the Coastal Sub-basin Exploratory Boring Program and a digital elevation mapping
study that analyzed the potential recharge from the nearby mountain front. The updated
report contains findings from this recently completed work as well as 2017 data
regarding rainfall, geology, static water levels in key wells, and groundwater withdrawals
from active City wells and other known private well owners (Attachment D). The
updated SYA estimate from Slade’s analysis for the Santa Monica Basin is between
11,800 and 14,725 AFY.
To substantiate the assessment conducted by Slade, City staff contracted with
consultants from ICF to perform a separate estimate of the sustainable yield using a
water-balance approach. This method compares the amount of water that recharges
into a basin (inflow) from a wide range of sources (natural and anthropogenic), with the
amount of water leaving the basin (outflow) from losses caused by pumping,
evapotranspiration, basin outflow, etc. ICF’s assessment also considered findings from
both the digital elevation mapping and Differential Interferometric Synthetic Aperture
Radar Study (DInSAR) studies, presented to Council in January 2018. Based on ICF’s
water-balance approach, average sustainable yield was estimated to be between
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11,416 AFY to 13,722 AFY. The similarity of the sustainable yield estimates developed
by Slade and ICF using different modeling methods provide a strong level of confidence
that the City can use local groundwater resources in an ongoing manner into the future
without negatively impacting the basin or creating overdraft conditions.
It should be noted that the estimates developed by Slade and ICF are conservative and
do not include a sustainable yield estimate for the Crestal Sub-basin. In addition, all
estimates of sustainable yield are transitory due to myriad associated climatic and
hydrogeologic factors that are constantly in flux. The State legislature enacted the
Sustainable Groundwater Management Act (Water Code sections 10720 et
seq.)("SGMA"), which became effective on January 1, 2015. A portion of the 50 -square
mile Santa Monica Basin that underlies Santa Monica has been designated by the
Department of Water Resources as a "medium-priority" groundwater basin. Any
groundwater basin designated as medium -priority must be managed under a
groundwater sustainability plan (“GSP”) adopted by a local groundwater sustainability
agency and approved by the Department, by January 31, 2022. In light of SGMA,
further analysis will be required to determine if future demand will exceed what could be
sustainably pumped from the basin. If it is determined that the City’s plans to extract
more groundwater is not supported in the approved draft of the GSP, then the City may
be precluded from withdrawing groundwater in excess of the then -projected sustainable
yield and the City would need to continue purchasing imported water from MWD to meet
its potable water demand. The potential limitations on future groundwater withdrawals
from the City’s active sub-basins indicate that the City’s approach of pursuing
nonconventional resources, indirect potable reuse via aquifer recharge, additional water
supply wells in the Coastal sub-basin, replacement of underperforming wells, increasing
treatment efficiency at the Arcadia Water Treatment Plant, and continuing conservation
efforts are necessary for the City to achieve and sustain its long-term objective of
independence from imported water. Future updates of the SYA and numerical models
will further refine the sustainable yield for the basin. Going forward, the City is planning
to update the SYA approximately every two to three years. Future updates will include
additional findings from work being conducted jointly with the US Geo logical Survey
(USGS) and an ongoing climate stress test evaluation by the Rand Corporation. The
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City plans to produce groundwater within the upper limit of the estimated sustainable
yield, while taking into consideration two irrigation pumpers in the Arca dia Sub-basin
and one in the Crestal in addition to one diminutive residential irrigation well.
Summary of Proposed Plan to Achieve Water Self-Sufficiency
The three components proposed in the SWMP will help the City achieve water self -
sufficiency by 2023 and eliminate the City’s reliance on imported water purchases from
the MWD. The projected makeup of the City’s water supply portfolio is summarized in
Figure 5, and contribution from each component to the City’s total water supply is
provided in Table 4. The location for each of the three components is provided in Figure
6, and the synergy and inter-relationship between each component is illustrated in
Figure 7. Achieving water self-sufficiency through a diversified water supply portfolio
also provides the City with greater cost control over water rates as compared to the
continued purchase of imported water from the MWD. As noted previously,
approximately 1 percent of the water supply would continue to be made up of imported
water purchased from the MWD as periodic circulation is required to maintain the supply
line as an emergency backup for the City.
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New Local
Groundwater
13%
Imported Water
(MWD)
1%Alternative Water
Supply -Purified
Water (Recharge)
Alternative
Water Supply -
Recycled Water
Alternative Water Supply -
Production Efficiency
Conservation
20%
Local Groundwater
47%
WATER SELF-SUFFICIENCY BY 2023
New Local Groundwater Imported Water (MWD)
Alternative Water Supply - Purified Water (Recharge)Alternative Water Supply - Recycled Water
Alternative Water Supply - Production Efficiency Conservation
Local Groundwater
Alternative
Water Supply
19%
Figure 5: A Sustainable and Drought Resilient Water Supply Portfolio Achieved through Self
Sufficiency
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Table 4: Summary of Water Supply Contribution from Each Self-Sufficiency Component
Water Self Sufficiency Component Estimated
Water Supply
Contribution
by 2023 (AFY)
%
Reduction
in Imported
Water
Estimated
$/AFY
Component 1 - Conservation
Optimal Conservation Plan 3,100 38% $708
Component 2 – Alternative Water Supplies
Recycled Water from SMURRF 560 7% $4201
Purified Water from SWIP to
Recharge Olympic Sub-basin
1,100 13% $1,0171
Increase Production Efficiency at
Arcadia WTP
1,200 15% $1,0711
Component 3 – New Local Groundwater Production
Arcadia WTP Expansion and
Resiliency Enhancement2
N/A N/A $7051
Olympic Sub-basin Restoration 2,100 26% N/A3
Subtotal 8,060 99%
Existing Water Resources
Existing Local Groundwater
(2023 projected costs)
7,330 $1,100
Imported Water from MWD
(to maintain for emergency use, 2023
projected costs)
170 $1,248
Subtotal 7,500
TOTAL WATER
RESOURCES (2023)
15,560
1Estimated year 1 cost when project is complete and includes savings from avoided imported water
purchase cost
2Aracadia WTP upgrades to accommodate increase in production efficiency and Olympic Sub-basin
Restoration
3Olympic Sub-basin Restoration will be paid for through settlement funds
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•Olympic Sub-Basin Restoration
•Recharge with SWIP
•Production Efficiency and Capacity
Expansion at Arcadia WTP
•Separate Olympic Pipeline +
New Treatment
•CBI Tank
•SWIP
Well Acquisition to
Enhance Resiliency
Figure 6: Project Locations of Proposed SWMP Component Toward Self-Sufficiency
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Figure 7: Synergy between Proposed Water Supply Components to Achieve Self-Sufficiency
SWMP Cost Summary and Implementation Schedule
A cost summary for the proposed SWMP components to achieve self -sufficiency by
2023 is provided in Table 5. The funding required to complete the capital projects
increasing local water supplies and enhance water supply resiliency is $38 million. A
Five-Year Rate Study (2020-2024) is currently underway and will present funding
solutions to cover these costs. It is projected that the components of the proposed
SWMP may be funded primarily through the issuance of water revenue bonds
(approximately $34.75 million), with the debt service on the bonds incorporated into
water rates, and from a contribution from the Wastewater Fund (approximately $3.25
million). Staff will return to Council in spring 2019 for a rate study session. An additional
$64 million from existing water-contamination settlement funds would be used for
restoring the Olympic Sub-basin, which would allow additional water production from
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that sub-basin to support water self-sufficiency. The Olympic Sub-basin restoration cost
includes an approximate, one-time $20 million capital expenditure for treatment systems
and 30 years of ongoing operation and maintenance for an additional $20 million. Based
on current modeling projections by ICF, over 80% of the Olympic Sub-basin will be
remediated within the first 30 years; however, the Sub -basin may not be completely
restored. Thus, the remaining balance in the settlement fund ($24 million) should be
reserved to address any contamination that may still be present after 30 years or any
new regulations that may impact use of the Olympic Sub-basin. A more detailed
discussion on recommended budget appropriations is provided below.
Table 5: SWMP Cost Summary for Proposed Components to Achieve Self-Sufficiency
Unfunded Projects Additional Cost
Arcadia WTP: Expand Capacity and Production Efficiency
Enhancement
$30M
Additional Well and Improvements: Increase Resiliency and
Ground Water Production
$8M
Olympic Sub-basin Restoration, Capital Improvements and 30
years of Operations and Maintenance
$40M
Olympic Sub-basin Restoration Reliability Reserve $24M
Total: $102M
Implementing the SWMP and reaching water self-sufficiency by 2023 entails numerous
capital projects that are interrelated. An overview of the proposed implementation
schedule is provided in Figure 8. Several well projects (SM-8, SM-9 and injection well)
were approved by Council on July 11, 2017 and on June 12, 2018 and are on track to
be completed by 2021 (Attachments E and F, respectively). A portion of the projects are
in the City of Los Angeles and require installation of pipelines. Construction and
permitting of pipelines in the City of Los Angeles will take time and was considered in
the schedule. The design, construction, and permitting of improvements at the Arcadia
WTP, including efficiency upgrades, are expected to be completed in 2023 if
procurement starts in December 2018. A schedule contingency of approximately six
months has been included to account for unforeseen conditions or new regulations that
could impact the plan implementation.
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Figure 8: Proposed Implementation Schedule to Achieve Self -Sufficiency by 2023
Alternatives to Water Self-Sufficiency
The proposed SWMP components summarized above are a considerable investment
towards the City’s future resiliency and achieving water self-sufficiency by 2023. In
consideration of the capital investment and impacts to water rates, staff has also
evaluated potential alternatives to reduce capital expenditures to potentially provide
relief to potential water rate increases (to be confirmed in the Five-Year Rate Study for
2020-2024). A summary of potential alternatives that may reduce upfront capital
investment compared to the proposed water self-sufficiency plan is provided in Table 6.
The capital cost summarized in Table 6 for each alternative is the capital cost that
needs to be funded and does not include the $64 million in settlement funds that will be
used for the Olympic Sub-basin restoration. For all alternatives, it is assumed that the
Olympic Sub-basin restoration will be implemented. A brief description on which
component is implemented and its associated capital cost to be funded is provided.
Staff also considered delaying self-sufficiency goal to beyond 2023 and delaying capital
expenditures to ease rate increase over the next five years. However, delaying
implementation may result in increasing overall project cost due to inflation and negate
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any potential up front capital savings. The alternatives summarized in Table 6 only
consider reduction in upfront capital cost and do not include projected increase of
imported water purchase from MWD (estimated to be at 5% annual increase), which will
ultimately be more expensive than locally produced water.
Table 6: Summary of Alternatives Considered for Self-Sufficiency
Alt. No. Alternatives
Description
Capital
Cost3
Locally Sourced
Water +
Conservation
Imported
Water
Purchase
from MWD
Staff
Recommended
Plan
99% water self-
sufficiency1 Component
1 - Conservation
Component 2 -
Alternative Water
Supplies Component 3 -
New Local Groundwater
$38M 11,730 AFY
(Existing Arcadia
WTP + Olympic)
3,100 AFY
(Conservation)
560 AFY
(Recycled
Water)2
170 AFY
1 87% water self-
sufficiency1 Implement
only SWIP and Olympic
Sub-Basin Restoration.
Acquire new well to
enhance resiliency at
Arcadia WTP. No
expansion and
production efficiency
enhancements at Arcadia
WTP
$8M 9,900 AFY
(Existing Arcadia
WTP + Olympic)
3,100 AFY
(Conservation)
560 AFY
(Recycled
Water)2
2,000 AFY
2 90% water self-
sufficiency1 Implement
SWIP, Olympic
restoration, and
expansion at Arcadia
WTP. No production
efficiency enhancements
at Arcadia WTP. Results
in loss and negative
impact to treatment
resiliency.
$21M 10,500 AFY
(Existing Arcadia
WTP + Olympic)
3,100 AFY
(Conservation)
560 AFY
(Recycled
Water)2
1,400 AFY
3 94% water self-
sufficiency1 Implement
SWIP, Olympic
Restoration, expansion
$30M 10,900 AFY
(Arcadia WTP +
Olympic) 3,100
AFY
1,000 AFY
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and production efficiency
upgrades at Arcadia
WTP. Do not acquire a
new well to enhance
resiliency.
(Conservation)
560 AFY
(Recycled
Water)2
1Percentages are based on year 2023 projected demand. 2560AFY of recycled water to be available in
2023, but actual usage of full capacity may not be until 2040. 3Excluding Olympic Sub-Basin restoration cost,
which is funded through settlement funds and SWIP capital costs as it is already funded through a low
interest loan from the State of California.
The alternatives evaluated by staff are simply presented as scenarios to reduce capital
expenditures over the next five years but does not provide a complete solution to
achieve the City’s water self-sufficiency goal.
Funding Recommendations to Achieve Water Self-Sufficiency
A financial analysis for the plan outlined in this report to achieve water self-sufficiency
was conducted by staff. The financial analysis includes comparing the future cost of
imported water to the projected cost of locally produced water over a 30 -year period.
This analysis excluded the Olympic Sub-basin restoration costs, as the recommended
funding source would be from groundwater settlement funds received by the City from
outside sources to cover the costs for remediating the contaminants in that sub -basin. In
summary, locally produced water from the recommended SWMP components outlined
in this report is projected to cost between $400/AFY to $1,100/AFY, which is less than
the expected cost to purchase imported water from the MWD at $1248/AFY in 2023.
Please refer to Table 5, presented previously, for a detailed breakdown on the cost per
acre-foot for each local water supply component. A comparison of the projected cost
differential between the purchase of imported water from the MWD and production of
locally produced water is provided in Table 7. With locally produced water cheaper than
imported water costs, the components outlined in the SWMP to achieve water self -
sufficiency by 2023 are a positive investment toward the future of the City. Ratepayers
will benefit from the implementation of these projects, thus keeping local water costs low
compared to the ongoing cost increases for imported water. Not only does the proposed
SWMP provide a sustainable and drought resilient water supply for the City, it would
also benefit the ratepayers with greater control over future water rates compared with
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imported water rates that are projected to increase at a higher rate and are outside the
City’s control.
Table 7: Future Estimated Imported Water Cost (increased at 5%) Compared to Projected
Locally Produced Water Cost. Assuming Efficiency (CCRO) technology is installed and
2,800AFY is produced.
As noted previously, staff recommends a combination of bonding and use of settlement
funds to fund the capital projects supporting water self-sufficiency and the Olympic Sub-
basin restoration.
Water Revenue Bond: A rate study is currently being conducted through October 2019
to set water and wastewater rates for calendar years 2020 to 2024. The rate study will
address options to support the costs of this plan. A possible funding solution, to be
confirmed in the rate study, is the issuing of a 30-year water revenue bond totaling
approximately $34.75 million to increase local water supplies and enhance resiliency as
outlined in the SWMP. The remaining $3.25 million would be contributed from the
Wastewater Fund due to joint property use. The $34.75 million in bonds would cover
new well acquisition, treatment capacity expansion and implementation of new
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technologies to enhance production efficiency at the Arcadia WTP, and other supporting
infrastructure upgrades. The Water Fund would need to cover an annual payment of
approximately $2.2 million over the next 30 years to fund the projects outlined in the
SWMP. Assuming a bond is issued, Figure 9 illustrates projected annual savings from
avoiding imported water purchases and estimated annual bond repayments. In year
2036, where the two lines cross, the City will start saving money for rate payers on an
annual basis. This analysis assumes imported water cost from MWD will increase at an
annual rate of 5%. The total money borrowed is estimated to be offset by cumulative
savings in the year 2048.
Figure 9: City’s Projected Annual Savings due to Local Water Production in lieu of Import
Water Purchases, compared to the Payments (debt service) for a 30 Year Bond.
Settlement Funds Usage - The current balance of Gillette/Boeing funds available to
program is $64.1 million. This balance includes $11.1 million transferred and currently
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available in the W ater Fund as authorized by Council on January 9, 2018 and $53.0
million in the General Fund. Staff recommends transferring $53.0 million from the
General Fund to the Water Fund to be used to restore the Olympic Sub -basin.
Additionally, to satisfy the settlement agreement, Boeing still owes the City three
payments totaling $11.0 million. Staff recommends depositing these funds directly into
the Water Fund.
Approximately $20 million would be used to construct a new treatment facility to remove
the contaminants currently present in the sub-basin and $20 million would be reserved
for operation and maintenance costs of the treatment facility related to restoration of the
Olympic Sub-basin over a 30-year period. Due to uncertainty with the Olympic Sub -
basin restoration after 30 years, staff recommends setting aside the remaining $24
million of Gillette/Boeing funds as a reliability reserve. The remaining $11.0 million that
has been previously transferred to the Water Fund, is currently being used for
groundwater modeling, monitoring, and reporting in support of Olympic Sub-basin
remediation.
With the proposed injection of advanced purified water from the SWIP into the Olympic
Sub-basin, staff will revisit this timeframe and report back to Council in the future o nce
recharge operation begins.
Grants - Staff will identify and apply for state and/or federal grants to help offset the $38
million capital investment and return to Council in early 2019 with resolutions required
for grant applications if available for the proposed projects. Staff has engaged a grant
consultant to assist in the process. Grants being considered are:
MWD, Local Resources Program
California Department of Water Resources, Water Quality, Supply, and
Infrastructure Improvement Act of 2014 (Proposition 1).
Previously Authorized Water Rate Increase
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On February 24, 2015, the City Council adopted Resolution Number 10867 (CCS) to
authorize water rate increases over a five-year period, beginning March 1, 2015.
The five-year water increase schedule was adopted after Council’s consideration of a
rate study conducted by Kennedy Jenks Consultants. Resolution Number 10867 (CCS)
also contained a provision, giving Council flexibility to approve a suspension of each
annual increase, in whole or part, beginning with the 9% scheduled increase for January
1, 2016. This resolution was adopted without a majority protest, following a noticed
public hearing in accordance with Proposition 218. Since adoption of this resolution,
Council has partially suspended the full increases authorized for 2016-2018, and
instead approved 5% increases for each of those years due to:
Actual water sales revenues exceeded expectations during 2015 to 2017.
Actual operating and capital expenditures lower than expected. Resu lting savings
were applied to conservation programs, water main replacements and partially
suspending planned 9% annual rate increases to more modest 5% increases.
State of the Water Fund and Forthcoming 2019 Rate Adjustment Justification
Staff will return to Council on January 8, 2019 for a public hearing and to obtain
authorization for the full 9% water rate increase previously approved by Council on
February 24, 2015 for calendar year 2019. If approved this would result in a monthly
increase of $4.33 to average single-family customer. This is the final year of a five-year
rate adjustment cycle approved via resolution as mentioned above.
A summary of rate increases from 2015 is provided in Table 8.
Table 8: Rate Increase History
Calendar
Year
2015 2016 2017 2018 2019
Effective Date March 1,
2015
January
1, 2016
January 1,
2017
January 1,
2018
January 1,
2019
Maximum
Authorized
Increase
9% 9% 9% 9% 9%
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Actual
Increase*
9% 5% 5% 5% 9%**
Date Actual
Increase
Authorized
February
24, 2015
February
23, 2016
November 22,
2016
January 9,
2018
**public
hearing on
January 8,
2019
The full implementation of the 9% previously authorized adjustment would be sufficient
to allow the City to:
A) Deliver potable water to Santa Monica customers reliably, safely and sustainably
in compliance with federal and state regulations.
B) Fund operating and capital budgets that are necessary to implement the City's
self-sufficiency goals to encourage water conservation and sustainability, as
contemplated in the City's 2014 water rate analysis.
C) Continue to implement infrastructure improvements associated with replacing
aging existing infrastructure facilities comprised of water mainlines that are
approaching the end of their useful lives.
The 9% rate increase would provide sufficient funding to complete the following capital
projects as contemplated in the City's 2014 water rate analysis and to continue progress
toward the City’s water self-sufficiency goal:
1. Additional capacity improvements, which include Preliminary Design for the
Arcadia Treatment Capacity Expansion and Enhancement Project - $3.18 million
in FY 2018-19. As noted in the prior section, the design would upgrade pumps,
blowers, cartridge filters, and other equipment at the treatment plant to
accommodate increased groundwater production and new technologies. The
design would also incorporate a new process (CCRO) to increase overall plant
efficiency to 90% or greater (as discussed previously under component 2 -
alternative water supplies.
2. New Groundwater Resiliency Well - $6,825,000 in FY 2018-19 for acquisition of a
new groundwater well to enhance resiliency. Also limit future exposure to
imported water.
3. Water Main Replacement Cost Escalation - an increase of $2,000,000 starting in
FY 19-20. The rate increase is necessary to fund the sharp increase observed in
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water main replacement construction costs. Water main contract awards in 2017
and 2018 have returned bids of $600 to $700 per linear foot in the current high -
cost construction environment. These costs have increased from a prior $400 per
linear foot estimate. The budget was established at $4 million per year. However,
staff is now estimating a need of $6 million per year to implement the
recommended 100-year water main replacement cycle (2 miles replaced per year
for the City’s 205-mile water main system. Maintaining a $4 million per year
budget would only yield replacement of 1.1 to 1.25 miles of pipeline per year,
thus increasing the replacement cycle from 100 years to approximately 160 to
190 years. Staff recommends staying on a 100-year replacement cycle to
maintain operational reliably.
Council approval of the full 9% rate increase would also help fund the following
ongoing operational expenditures:
1) Metropolitan Water District (MWD) of Southern California - $5 million per year
from FY 2020-21 to FY 2022-23 (additional $8.7 million) to ensure sufficient
funding for imported water deliveries prior to achieving water self -sufficiency.
2) City Yards Master Plan - Required contribution from the Water Fund for
upgrades to City Yards - $4 million modeled, actual costs to be determined.
As noted above, staff will return to Council on January 8, 2019 with a recommendation
that Council adopt the full 9% rate increase for calendar year 2019 as previously
authorized in 2015. The staff report will include a detailed justification for the 9% rate
increase as well as a 10-year fund forecast, cost comparison with other water agencies
and an analysis of impacts to ratepayers.
Funding Summary
Table 9 provides a summary of funding recommendations to implement the SWMP. As
noted above, staff also recommends that Council approve funding for three Capital
Improvement Program (CIP) projects, which would commence in FY 2018 -19:
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Arcadia Capacity Expansion and Enhancement Project, Preliminary Design
($3,180,000)
New Groundwater Resiliency Well ($6,825,000)
Olympic Wellfield Restoration Design ($1,800,000).
Table 9: Funding Summary
Settlement
Funds
Available for
current
remediation
and O&M for
next 30 years
Settlement
Funds
Available for
Future Reserve
(Olympic sub-
basin
Restoration)
Water
Bond
Amount
(pending
ongoing rate
study)
Est. Annual
Bond Payment
(30 yrs):
$40 million $24 million $34.75 million $2.2 million
Task Force on the Environment and Water Advisory Committee Actions
Findings of the Sustainable Yield Analysis, Sustainable Water Master Plan Update and
proposed projects, cost and schedules were presented to the Task Force on the
Environment on March 19, June 18, and October 15 and to the Task Force on the
Environment Water Subcommittee on November 19, 2018. Similar updates were
presented to the Water Advisory Committee on March 5, May 7, June 4, September 5
and November 5, 2018.
Rate Adjustment recommendations were presented to the Water Advisory Committee
on November 5, 2018 and at a Task Force on the Environment Water Subcommittee on
November 19, 2018. The Water Subcommittee strongly supports the Sustainable Water
Master Plan Update and staff’s recommendations.
Financial Impacts and Budget Actions
Approval of the recommended action requires the following:
1. Appropriations to the FY 2018-19 Capital Improvement Program in the Water
Fund:
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Account Number Amount
C5007740.689000 - Arcadia Capacity Expansion and
Enhancement Project, Preliminary Design
$3,180,000
C5007750.689000 - Olympic Wellfield Restoration Design $1,800,000
C5007760.689000 - New Groundwater Resiliency Well $3,575,000
Total $8,555,000
2. An appropriation to the FY 2018-19 Capital Improvement Program in the
Wastewater Fund
C5107760.689000 - New Groundwater Resiliency Well, Property
Joint Use.
$3,250,000
Total $3,250,000
3. $53 million cash transfer of Gillette/Boeing settlement funds from the General
Fund to the Water Fund and the corresponding release of the remaining fund
balance in General Fund account 1.380237. The cash will be recorded in an
interest earning restricted cash account in the Water Fund, Olympic Wellfield
Remediation account 50.102442.
4. Transfer of two remediation capital projects, appropriated in previous fiscal years
and funded with Gillette/Boeing funds, from the General Fund to the Water Fund
to consolidate all budgeted Olympic restoration projects in the Water Fund.
General Fund Account Number Proposed Water Fund
Account
Amount
C019045.589000 Olympic Sub-basin
Remediation
C5005880.689000 $1,909,732
C019067.589000 Olympic Sub-basin Well
Hydrology
C5006050.689000 $1,946,407
5. The following budget items related to Gillette/Boeing water mediation settlement
funds were previously taken by Council:
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On January 9, 2018, Council authorized staff to make an $11,100,000
transfer of Gillette/Boeing settlement funds from the General Fund to the
Water Fund for ongoing and future remediation costs associated with polluted
groundwater in the Olympic Wellfield (Attachment B). Staff transferred these
funds to account 25695.570080 in FY 2017 -18.
On June 12, 2018, Council approved a FY 2018 -19 transfer of $2,300,000 of
Gillette/Boeing water mediation settlement funds from the General Fund to
the Water Fund (Attachment F). This transfer was to fund the projects for the
Olympic Wellfield remediation appropriated in the FY 2018-19 Capital
Improvement Program.
Account Number Amount
C5007460.689410 City / USGS Monitoring Well & Numerical Flow
Model
$1,800,000
C5007260.689410 Redrill Santa Monica Well #3 $500,000
Total $2,300,000
6. Future Gillette/Boeing settlement funds are to be deposited in the Water Fund,
and a corresponding receivable shall be established. The liability associated with
current and future pollution remediation utilizing Gillette/Boeing funds will be
recorded in the Water Fund.
Prepared By: Alex Nazarchuk, Interim Water Resources Manager
Approved
Forwarded to Council
Attachments:
A. October 28, 2014 Staff Report (Web Link)
B. January 9, 2018 Staff Report
C. Summary of Water Self-Sufficiency Scenarios to Expand Groundwater
Production
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D. Updated Preliminary Sustainable Yield Analysis
E. July 11, 2017 Staff Report (Web Link)
F. June 12, 2018 Staff Report (Web Link)
City Council
Report
City Council Meeting: January 9, 2018
Agenda Item: 9.A
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To: Mayor and City Council
From: Susan Cline, Director, Public Works, Water Resources
Subject: Calendar Year 2018 Water Rate Adjustment
Recommended Action
Staff recommends that the City Council:
1. Suspend the 9% water rate increase authorized to go into effect on January 1,
2018 and authorize a 5% increase to be in effect until December 31, 2018; and
2. Authorize the budget changes as outlined in the Financial Impacts & Budget
Actions section of this report.
Executive Summary
The City of Santa Monica has historically provided water service to our residential and
business customers. Given the statewide challenges surrounding safe and reliable
water supply in recent years, Santa Monica has been a leader in efforts to conserve,
reuse and safeguard our local water resources. This report addresses the annual water
rate recommendation for calendar year 2018 and provides a progress update on various
efforts undertaken to meet the City’s ambitious goal of eliminating use of imported water
and becoming water self-sufficient by 2020.
On February 24, 2015, Council approved a series of five annual 9% water rate
increases for the period of March 1, 2015 through December 31, 2019 (Attachment A).
The resolution adopting the water rates provided City Council with flexibil ity to suspend
all or a portion of each 9% annual rate increase during the five -year rate period,
depending upon circumstances which demonstrate that such increases are
unnecessary due to greater than anticipated revenues, decreased operating expenses
or decreased capital projects expenditures. The first 9% increase went into effect on
March 1, 2015. On February 23, 2016 and November 22, 2016, due to better than
expected financial results, Council approved 5% increases for calendar years 2016 and
2017, respectively, partially suspending scheduled 9% increases (Attachments B and
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C). Review of Water Fund performance for Fiscal Year 2016 -17 indicates that revenues
were $0.6 million greater than anticipated and expenditures were $8.6 million less than
anticipated, leaving the Water Fund with a $36.7 million fund balance. Staff therefore
recommends that City Council adopt a 5% water rate increase for 2018 instead of the
previously approved 9% increase. Better than expected financial performance in Fiscal
Year 2016-17 has allowed for this reduced rate adjustment while still providing sufficient
funds to conduct studies necessary to inform the Sustainable Water Master Plan update
and future rate recommendations.
The recommended rate adjustment would be sufficient t o allow the City to:
1) Deliver potable water to Santa Monica customers reliably, safely and sustainably
in compliance with federal and state regulations; and
2) Fund operating and capital budgets that are necessary to implement the City's
self-sufficiency goals to encourage water conservation and sustainability, as
contemplated in the City's 2014 water rate analysis. Such projects include five
FY 2017-18 capital projects to improve reservoir chlorination ($900,000), perform
pilot reverse osmosis upgrades at the Arcadia Water Treatment Plant
($250,000), commence preparation of a Groundwater Sustainability Plan for the
Santa Monica Basin ($150,000), conduct a supplemental study to refine the
Sustainable Yield Analysis ($100,000), and complete a flow modelling stu dy
required for future reuse of recycled water ($300,000).
The recommended 5% water rate increase would be effective for calendar year 2018 on
bills issued on or about March 1, 2018. Proposed and current water and fire line service
rates are listed in Attachment D. Council may take action to adjust future rates at the
next annual review.
The 2014 water rate study was prepared in conjunction with the preparation of the
Sustainable Water Master Plan (SWMP). In 2014, City Council adopted the SWMP with
the goal of eliminating reliance on imported water from Metropolitan Water District and
achieving water self-sufficiency by 2020. Since the adoption of the SWMP and as a
result of new water conservation programs/policies implemented in 2015 and 2016, the
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City has seen a 16 percent reduction in water use while the residential population has
grown from 92,321 to 93,282 over the same period. Overall, through its efforts to
address the drought, the City has achieved and continues to maintain a nearly 20%
reduction in water use relative to its 2013 baseline. This reduction has allowed the City
to further reduce its use of imported water by 11 percent. Currently, the City’s water
supply consists of approximately 25 percent imported water and 75 percent local
groundwater. Per capita water use has maintained steady at 110 gallons per capita per
day (GPCD) in 2016 versus record low usage of 109 GPCD in 2015.
Staff initiated a comprehensive update of the Sustainable Water Master Plan earlier this
year. Significant progress has been made on the completion of that plan, including
completion of a preliminary Santa Monica Basin sustainable yield analysis, which
evaluated the rate (volume) at which groundwater can be pumped on a perennial basis
without depleting the resource, a key element in achieving the water self-sufficiency
goal
Based on the work completed to date, staff believes further analysis is needed in order
to assess whether the City will meet its water self-sufficiency goal by 2020, including
what added measures are needed to eliminate reliance on imported water. .
Specifically, analysis to validate the sustainable yield estimates, determine availability
and costs to access potential additional local groundwater resources, and evaluate the
cost and viability of additional water conservation programs as requested by the Task
Force on the Environment are required. This work is currently underway and is
expected to be completed in late spring 2018 and will be incorporated into an updated
SWMP. The updated SWMP will be presented to Council in mid-2018 and will include a
detailed progress report and timeline for achieving the water self -sufficiency goal and
maintaining an ongoing sustainable local water supply.
Background
On February 24, 2015, Council approved the following schedule of water rate increases
via resolution subject to an annual State of the Water Fund review analyzing fiscal
performance and projected fund balances over a five-year period:
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Calendar Year 2015 2016 2017 2018 2019
Effective Date March 1,
2015
January
1, 2016
January 1,
2017
January 1,
2018
January 1,
2019
Maximum
Authorized Increase
9% 9% 9% 9% 9%
Actual Increase* 9% 5% 5%
*Actual Increase adopted by Council based upon review of Water Fund performance
Rate increases go into effect automatically on an annual basis unless suspended, all or
in part, by Council. On February 23, 2016, based on an improved financial outlook,
Council partially suspended the full 9% increase and approved a 5% increase for
calendar year 2016. On November 22, 2016, based on better than expected financial
performance, Council partially suspended the full 9% increase and approved a 5%
increase for calendar year 2017. The rate increase for 2017 provided funding to
increase the City’s water main replacement budget from $2 million to $4 million per year
in order to meet a 100-year replacement schedule which will increase the resilience of
the water system and help to prevent water main breakages.
For financial stability, the Water Fund strives to maintain a $7 million minimum reserve
balance with revenues sufficient to cover all operating and capital expenditures while
meeting various water-related requirements and goals including:
20% reduction in water use from 2013 levels mandated by the State from May 5,
2015 through May 2016, and current City Stage 2 Water Supply Shortage
conditions adopted by Council on August 12, 2014 in accordance with the City’s
Water Shortage Response Plan;
Meeting a State-required 123-gallon per capita per day usage standard per the
Water Conservation Act of 2009 also known as SBx7 -7;
Federal & State water quality and treatment requirements;
Achieving Santa Monica's goal of reducing the City's reliance on imported water
and attaining 100% water self-sufficiency by 2020;
Managing Santa Monica basin groundwater contamination and utilizing
groundwater resources in a sustainable manner; and
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Maintenance and construction of water treatment and distribution systems
including facilities, meters, pipelines, pump stations, reservoirs and well fields for
reliable and efficient delivery of potable water for customer use.
The approved 9% annual increases may be suspended in whole or part if revenues are
greater than anticipated or expenditures are less than expected, while maintaining a $7
million minimum reserve Water Fund balance at the end of the five-year planning
horizon.
Any 2018 rate increase would go into effect for water consumption beginning on
January 1, 2018, effective on water bills prepared on or after March 1, 2018 as water
meters are read approximately every two months (e.g., a bill issued for a meter read on
March 1, 2018 would reflect water usage from January 1 to February 28, 2018).
Water Units of Measure, as the City uses, are in units of hundred cubic feet (HCF) for
water billing purposes, where 1 HCF = 748 gallons. Discussion in the first portion of the
staff report related to water rates, individual customer bills, and Water Fund financial
performance will reference quantities in HCF units. As the City imports water from the
Metropolitan Water District (MWD) of Southern California in units of acre-feet (AF),
where one acre foot = 325,851 gallons or 435.6 HCF, discussion in the second portion
of the staff report related to the City’s overall progress towards water self -sufficiency will
reference quantities in acre-feet.
Discussion
State of the Water Fund and Rate Recommendation
Fiscal Year 2016-17 Financial Performance
In considering whether to suspend all or part of the scheduled 9% rate adjustment for
calendar year 2018, staff analyzed the FY 2016-17 actual performance of the Water
Fund. The Water Fund ended Fiscal Year 2016-17 with a fund balance of $36,727,423,
$9.2 million better than expected primarily due to lower than expected capital and
operating expenditures while achieving revenues just above expectations. The fund
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balance includes the one-time infusion of $33.4 million in Charnock Fund MTBE
settlement funds at the end of FY 2012-13 which is being used to fund increased capital
and conservation programs; and ongoing monitoring, remediation and permitting
activities for the Charnock Well Field.
Revenues – FY 2016-17 potable water sales of 4,991,022 hundred cubic feet
(HCF) increased by 2.5% versus record low usage of 4,870,900 HCF in FY 2015 -
16, resulting in sales revenues exceeding budget by $0.4 million and total Water
Fund revenues exceeding expectations by $0.6 million. Although overall water
usage remains approximately 20% below the City’s 2013 baseline, m odest year-
over-year increases were observed for the three customer classes which account
for approximately 93% of City usage: Multi-Family Residential (+1.7%),
Commercial (+2.6%) and Single Family Residential (+2.8%).
Expenditures – FY 2016-17 capital and operating expenditures were $8.6 million
less than expected. Key line items include:
o Capital Expenditures were $3.6 million less than projected – virtually all of
these funds are for ongoing projects and programs which will be rolled
over into FY 2017-18 and spent pending bids and completion of design
work for projects related to water main replacements ($1.5 million), facility
repairs ($1.25 million), irrigation controllers & turf removal at City sites
($540,000), and software and control systems ($312,000).
o Expenditures for Water Conservation Programs were $1.7 million less
than projected – turf removal rebates ($585,000 of $1.5 million budgeted)
and multi-family toilet installation program ($80,000 of $678,000 budgeted)
expenditures were significantly lower than expected due to staffing
vacancies and contracting delays.
o Water Treatment and System Maintenance Materials & Services were
$900,000 less than projected – expenditures for water treatment
chemicals, maintenance supplies and professional services were less than
expected.
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o Charnock Well Field Operations were $850,000 less than projected –
purchases of activated carbon required to treat groundwater to remove
Methyl Tertiary Butyl Ether (MTBE) and other contaminants continued to
drop as clean-up of the Charnock Sub-basin continues. Only twenty-one
20,000-lb deliveries of activated carbon were required in FY 2016-17
compared to 40 deliveries in FY 2013-14, which was the highest year of
carbon use.
o Salaries & Wages were $600,000 less than projected – the Water
Resources Division experienced several key staff vacancies in FY 2016-
17, including four positions vacant for longer than six months.
o The Cost to purchase water was $300,000 less than projected.
Rate Recommendation
Due to an improved financial outlook and the need to do additional analysis t o
determine the project and financial needs to achieve water self -sufficiency, staff
recommends Council partially suspending a portion of the 9% water rate increase
authorized by Council and authorize a 5% increase for calendar year 2018. Comparing
rates with the 15 other Metropolitan Water District (MWD) of Southern California
member cities, Santa Monica’s tiered rate structure would continue to offer close to the
lowest costs in the region for the average user. For a single-family residence using the
City average of 25 HCF (18,700 gallons) over a two-month period, a 5% increase would
raise a bi-monthly water bill by $4.63 from $91.64 to $96.27, which works out to about a
half-cent per gallon ($0.00515). Anaheim currently offers the best pricing at $84,
followed by Fullerton at $89 and El Segundo at $95 as indicated in the following chart:
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The 5% rate adjustment would provide for continued delivery of water service, including:
Sufficient funding to maintain safe and reliable water deliveries for Santa Monica
customers at a reasonable cost while meeting federal and state regulations and
City water usage restrictions;
Continued funding toward projects and programs needed to continue progress
toward the City’s water self-sufficiency goal
Continued investment in infrastructure and conservation programs; and
Meeting or exceeding bonding capital requirements; and the financial stability to
allow for fluctuations in water usage and to address unforeseen operating and
capital budget requirements.
The following anticipated costs and budgeted projects are included in the Water Fund’s
5-year fund balance projection (Attachment E):
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Metropolitan Water District (MWD) of Southern California – $5.4 million from FY
2019-20 to FY 2021-22 to ensure sufficient funding for imported water deliveries
prior to achieving water self-sufficiency and ongoing access to imported water if
needed in case of emergency. After 2020, the City anticipates costs for
continued access to MWD water (including fixed “Readiness to Serve” and
“Capacity” charges which have totaled $1.0 million to $1.2 million per year in
addition to per acre-foot charges for water imported) to serve as a backup source
in case of City water production interruptions or to meet peak demand
requirements.
Coastal Sub-Basin Exploratory Borings and Well SM-7 Replacement Project –
$4.2 million in FY 2017-18 to evaluate groundwater availability and quality in the
Coastal sub-basin by drilling three borings/production wells at the Santa Monica
Airport, Colorado Yards and 2018 19th Street; and replace an inactive well (SM-
7) located near Olympic / Stewart with a new production well.
Water Neutrality Ordinance – added $2.1 million in FY 2017-18 costs for
contractor services to implement the ordinance for new development permits a nd
to identify/ensure compliance with water usage offsets. Staff anticipates that
Water Neutrality fees effective for permit applications submitted on or after July
1, 2017 coupled with the cessation of Water Demand Mitigation fees ($3 per
gallon per day of estimated new net water use collected to fund water
conservation programs at municipal sites) will lead to revenues that are
approximately $560,000 less than total program costs, which is due to one-time
non-recoverable program start-up costs for implementing this water conservation
program.
Staff also recommends Council approve funding for five Capital Improvement Program
(CIP) projects, which would commence in FY 2017-18, and reduce budgets for two
projects for a total of $549,982:
Potable Water Reservoir Improvements ($900,000) – To improve chlorination
and reduce nitrification at the City’s three reservoirs (Mount Olivet, Riviera and
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San Vicente), additional mixers, chemical dosing and analyzer equipment would
be installed.
Arcadia Water Plant Enhanced Reverse Osmosis Recovery Pilot ($250,000) - To
increase the efficiency of the City’s water treatment process from the current
82% (82 gallons of finished water are produced from 100 gallons of raw water) to
approximately 90%, which could yield an additional 672 acre-feet per year (AFY)
from the same amount of groundwater, the City would pilot a new full-scale
treatment skid on a rental basis including membranes, pumps and analyzer
equipment to process reject water currently disposed into the sewer. Depending
on the success of the pilot, staff would return to Council to consider purchasing
the rental equipment (estimated at $2 million), with full cost recovery possible
within two to four years due to savings from reduced MWD water purchases.
Santa Monica Basin Groundwater Sustainability Plan ($150,000) - To develop a
state-required Groundwater Sustainability Plan by January 2022 to manage
Santa Monica Basin groundwater in concert with the Los Angeles Department of
Water and Power, the County of Los Angeles, the City of Beverly Hills and the
City of Culver City, an additional $150,000 in FY 2017 -18 would be added to the
City’s current $50,000 budget for plan development and facilitation of regular
interested party meetings. Actual costs may be higher or lower dependent on the
cost-sharing agreement negotiated with the other signatory agencies of the
Santa Monica Basin Groundwater Sustainability Agency.
Supplemental DInSAR Study ($100,000) - This study will supplement data
collected as part of the preliminary Differential Interferometry Synthetic Aperture
Radar or DInSAR subsidence study completed earlier this year. The study is
intended to better assess how the local groundwater basins and sub-basins are
recharged and will allow further refinement and finalization of the Sustainable
Yield Analysis (SYA) for the basin.
US Geological Survey (USGS) Numerical Flow Model ($300,000) – Completion
of this model is required for the City to obtain a recharge permit that would allow
future injection of treated recycled water from the Sustainable Water
Infrastructure Project (SWIP) into local aquifers for reuse. USGS has completed
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a detailed groundwater flow model for most of the LA Basin. Staff has met with
the USGS to begin the process of working cooperatively to extend the USGS
model into the Santa Monica Basin by sharing our existing modeling with the
agency. These activities would utilize the City’s currently contracted modeling
expert (ICF Engineers) to interface with the USGS modeling team. Work would
initially focus on the Charnock and Olympic sub-basins. The objective of the
modeling program is to have a preliminary calibrated model for the sub-basins
the City currently pumps by 2020.
Arcadia Water Treatment Plant Reverse Osmosis Membrane Replacement
Project ($700,000 budget reduction) – in November 2017, the City completed
replacement of 1,608 reverse osmosis membranes used in the treatment of
potable water. Initially budgeted at $1.5 million, actual costs were $800,000,
yielding $700,000 in savings available to defray the project costs above.
Water / Wastewater Tenant Improvement Projects – to reflect the deferral of
Water / Wastewater building modifications at the City Yards to accommodate
staff currently located at 1212 5th Street not included in Phase I of the City Yards
Master Plan, staff also recommends Council approve FY 2017/18 CIP reductions
$450,018 for the Water Fund and $1,950,017 for the Wastewater Fund originally
slated for design and construction. Pending further City Master Plan design and
planning work, these modifications will be taken to Council as part of the FY 18 -
20 Biennial CIP budget submittal with updated cost and timing estimates
(currently, approximately $3.9M apiece has been included in the 5 -year budget
forecasts for both the Water and Wastewater Funds).
Alternatives
As currently modeled, an increase lower than a 5% increase for calendar year 2018
would cause the Water Fund to drop below the $7 million minimum recommended
reserve balance by the end of FY 2021-22. If rates are not increased at all, the fund
balance would be projected to drop to $1.6 million at the end of FY 2021 -22.
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While an increase greater than 5% might provide additional resources for accelerating
progress toward the 2020 water self-sufficiency goal, the completion of the ongoing
studies will provide a clearer roadmap for making those decisions in the years ahead.
Similarly, diverting from the recommended capital investments by adding or deleting
proposed projects could either delay or accelerate progress toward the City’s goal of
providing safe water, meeting its water self-sufficiency goal and/or meeting the State’s
Groundwater Sustainability Plan requirement by 2022. Again, the completion of the
current analyses will provide a better guide for future i nvestments beyond the ones
recommended in this report.
Despite having a larger than normal $36.7 million Water Fund balance primarily due to
the one-time infusion of $33.4 million in Charnock Well Fund MTBE settlement funds at
the end of FY 2012-13, it is anticipated that significant investments in capital ($42
million) and conservation ($17 million) programs will cause expenses to outpace
revenues in each of the next few years. The five -year Water Fund forecast currently
models in an approved 9% rate increase for calendar year 2019, with any future
changes in future years to be determined by a future rate study. However, actual rate
adjustments will be set by Council for 2019 based on an annual financial performance
review, which has been better than expected over the past three years leading to
reduced rate increases; and for 2020 to 2024 based on an upcoming Water/Wastewater
rate study to be considered by Council in 2019 and subject to Proposition 218
notifications to all rate payers and public hearing requirements.
Progress Toward Meeting Water Self-Sufficiency Goal
In 2014, City Council adopted the Sustainable Water Master Plan (SWMP) with the
ambitious goal of eliminating reliance on imported water from Metropolitan Water
District (MWD) and achieving water self-sufficiency by 2020. Since the adoption of the
SWMP and as a result of new water conservation programs and polic ies implemented in
2015 and 2016, the City has seen a 16 percent reduction in water demand while the
residential population has grown about 1 percent over the same period. Overall, through
its efforts to address the drought the City has achieved and continues to maintain a 20%
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reduction in water use relative to its 2013 baseline. This reduction in water demand has
allowed the City to further reduce its use of imported water by 11 percent. Figure 1
below indicates the continuing reduction in the City’s imported water supply over the
five-year period from 2012 to 2016.
Figure 1
From 2007 to 2016, the population increased from 8 7,860 to 93,282. Nevertheless, as a
result of long-standing successful conservation efforts by the City of Santa Monica, per
capita water use (total city water use divided by population) has continued to decrease,
as indicated in Figure 2 below.
Figure 2
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Water Conservation Program Update
The City’s past and current water conservation efforts include a combination of incentive
programs, regulations, enforcement, and outreach and education programs. For the
2014-2017 time period, the programs and policies that the Water Conservation Unit
within the City’s Office of Sustainability and the Environment (OSE) has implemented
and executed can be categorized as follows:
2014 Sustainable Water Master Plan programs
New program enhancements to existing programs
Ordinances for new developments and water waste
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Of all the factors shaping Santa Monica’s water conservation programs since the initial
SWMP, the most significant have been the recent five -year (2012-2017) California
drought and the resultant mandatory water use reductions and water conservation
requirements issued by both the State and the City.
Although Water Conservation Unit staff resources were devoted primarily to new water
conservation efforts in response to the 2012-2017 California drought, 10 of the
programs defined in the 2014 SWMP were initiated with significant progress.
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Water conservation programs implemented by the Water Conservation Unit have
significantly reduced water demand since the 2014 SWMP:
Total annual demand shrank by 1,578 acre-feet (AF) from 2014 to 2016.
Because the SWMP water conservation programs implemented to date have an
estimated 317 acre-feet per year (AFY) savings, the additional 1,261 AFY in
savings can be primarily attributed to new water conservation programs along
with enhancements to long-standing legacy programs.
Drought response reduction targets of 20% mandated by the State and the City
were consistently met.
The City’s Stage 2 Water Supply Shortage and the requirement for 20%
reduction in water use remains in effect (via Water Use Allowances and
Exceedance Citations), and the City continues to meet this target even with the
Drought State of Emergency rescinded and the media spotlight no longer on the
drought.
The City surpassed the State of California Water Conservation Act of 2009
(SBx7-7) target of 123 gallons per capita per day (GPCD) in 2014 and by 2016
had achieved a water demand of 110 GPCD. In September 2017, the Task Force
on the Environment recommended that the City commit to further reductions in
water demand to achieve a goal of 90 GPCD by 2025. As discussed later in this
report, a detailed work plan for achieving this goal is being evaluated as part of a
comprehensive update of the SWMP, which will be presented to Council in mid -
2018. However, staff expects that increased water conservation necessary to
meet this goal could be achieved in part by focusing on untapped areas such as:
o Yet to be implemented programs from the 2014 SWMP (most notably the
Santa Monica-Malibu Unified School District retrofits, St. John’s fixture
retrofits and coin-operated laundry machine retrofits).
o Increased focus on the commercial sector for rebates on water-saving
devices (especially flush-o-meter toilets and urinals).
o Continued aggressive water-waste enforcement.
o Additional sustainable landscape conversions.
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o Outreach program assisting customers to properly adjust their irrigation
timers.
o New marketing and outreach campaign focusing on permanent
conservation in line with the State’s forthcoming framework for “Making
Water Conservation a California Way of Life.”
Additional Progress on 2014 SWMP Implementation and SWMP Update
Preliminary Sustainable Yield Analysis
As noted above, the City’s water supply currently consists of approximately 25 percent
imported water and 75 percent local groundwater. Given the significant City-wide
reductions in water use over the past three years and the identification of new
opportunities to cultivate local water resources, the City hired Black and Veatch
Corporation to complete a comprehensive update to the 2014 Sustainable Water Master
Plan. Work began on this update in July 2017. To inform this effort staff also hired
Richard Slade and Associates to complete a Preliminary Sustainable Yield Analysis
(SYA) of the various groundwater sub-basins from which the City is pumping
groundwater in the larger Santa Monica Basin. The Preliminary SYA has been
completed and is included as (Attachment F) to this report.
The term “sustainable yield” is generally defined as the rate (volume) at which
groundwater can be pumped from an aquifer or basin on a perennial basis under
specified operating conditions without producing an undesirable result. Undesirable
results include, among other things, the unsustainable reduction of the groundwater
resource, degradation of groundwater quality, land subsidence and uneconomic
pumping conditions. Groundwater in the Basin is replenished primarily from precipitation
falling on the entire Basin and along the approximately 36-square-mile front of the Santa
Monica Mountains adjacent to the northern boundary of the Basin. Since the Basin is
heavily developed and a large portion of the available ground surface has been paved
to construct roads and other infrastructure, only a limited portion of exposed soils are
impervious and capable of allowing infiltration of surface water into the subsurface
water-bearing geologic formation.
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The Preliminary SYA study estimated sustainable yields for the Arcadia, Charnock and
Olympic sub-basins, which are the only sub-basins currently pumped by the City.
These are presented below in Table 2:
Table 2
GROUNDWATER SUBBASIN
CURRENTLY CALCULATED
SUSTAINABLE YIELD
(AFY)
Arcadia 600 to 800
Charnock 4,600 to 5,900
Olympic 1,600 to 1,700
TOTALS: 6,800 to 8,400
Coastal Assessment in Progress
Crestal Yet To Be Determined
Previous estimates of sustainable yield of the combined Arcadia, Charnock and Olympic
sub-basins by various experts retained by the City have ranged between 9,695 -13,475
acre-feet per year (AFY). These previous estimates relied heavily on literature
searches and localized data. The current study provides an analysis based on actual
pumping and recharge data over a period of 30 years. The information is preliminary,
and conservative, based solely on the three basins from which the City currently draws
water. As detailed below, additional work is currently underway to refine the preliminary
SYA results. This work involves completing exploratory borings in the Coastal sub -
basin, digital land mapping and remote sensing efforts; staff anticipates the safe yield
estimates will be adjusted once the additional work is completed in Spring 2018.
Exploratory Borings
The City currently has no wells in the Coastal sub-basin and little reliable geologic data
is available. However, based on a test well drilled adjacent to City Hall in 2017 it is
anticipated that the sub-basin could hold significant groundwater reserves. To assess
the availability and quality of groundwater that might be present, the City is drilling three
deep (600 ft.) exploratory borings in the sub-basin to document hydrogeological
conditions (Council action July 11, 2017, Attachment G). This project began in
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September 2017 and will be completed in early 2018. Initial results indicate that at least
one of the drilling locations may be suitable for installation of a future production well.
Full results and future recommended actions will be presented to Council as part of the
updated Sustainable Water Master Plan in mid-2018.
Digital Elevation Mapping
A supplemental study related to the SYA addresses how surface water runoff becomes
available for recharge (replenishment of the groundwater supply) and consequently,
how water in storage is calculated. The recharge rates used in the preliminary SYA
include a simple calculation of recharge from the mountain areas, which likely
underestimates recharge to the basin. Staff has initiated a study utilizing computer -
assisted modelling of irregular elevation data to provide a more accurate estimate of
available runoff.
Differential Interferometry Synthetic Aperture Radar Studies (DInSar)
Differential Interferometry Synthetic Aperture Radar (DInSAR) is a satellite-based
remote sensing technique capable of detecting minute variations (deformation) of
surface topography over time. In order to evaluate if historic and ongoing groundwater
withdrawals by the City may have resulted in large scale sediment compaction (land
subsidence) which could adversely affect the amount of groundwater storage in the
basin, a preliminary DInSAR study (Attachment H) was conducted as part of the
Preliminary SYA. The study determined that historic or ongoing Basin-wide sediment
compaction (land subsidence) was not evident, and also identified previously unknown
groundwater recharge pathways in the basin. Two additional remote sensing studies
will be completed to further evaluate this preliminary information and refine the
preliminary SYA study.
Current and Planned Efforts to Increase Local Supply
In addition to water conservation programs staff have initiated or are planning several
projects intended to increase local water supplies and further reduce the need for
imported water in order to meet the City’s water self-sufficiency goal. These are
summarized below.
20 of 28
Clean Beaches Project
In June 2017, Council approved a contract for construction of the Clean Beaches
Project for the Pier watershed (Attachment I). The Project involves construction of a
below ground stormwater harvesting tank, which will improve beach water quality by
collecting stormwater discharges to the ocean at the Pier outfall. The Project will
harvest up to 1.6 million gallons (MG) of storm water from any single storm event for
advanced treatment, recycling and reuse. The harvested water will be treated at the
Santa Monica Urban Runoff Recycling Facility (SMURRF) for non-potable uses
such as irrigation and toilet flushing. Construction began in September 2017 and is
expected to be completed by August 2018.
Sustainable Water Infrastructure Project (SWIP)
The SWIP is composed of three integrated project elements to help improve drought
resiliency, increase water supply and enhance flexibility in the management of the City’s
water resources. SWIP Element 1 involves the installation of a containerized
brackish/saline reverse osmosis and enhanced disinfection treatment system at the
SMURRF. When operational, the reverse osmosis/disinfection unit would be utilized to
advance treat non-conventional water resources such as urban and wet weather runoff
harvested by the Clean Beaches Project for later reuse. SWIP Element 2 includes the
construction of a below ground Advanced Water Treatment Facility (AWTF) at a location
beneath the Civic Center parking lot. The AWTF would advance treat approximately 1.0
million gallons per day (MGD) of municipal wastewater for reuse. SWIP Element 3
consists of two below-grade stormwater harvest tanks. One tank (3.0 MG) would be
constructed beneath Memorial Park. The other below-grade tank (1.5 MG) would be
located adjacent to the AWTF beneath the Civic Cen ter parking lot. Together, the
Project elements would produce approximately 1.5 MGD (1,680 acre-feet/year) of new
water for immediate non-potable reuse, and when appropriately permitted, for indirect
potable reuse via aquifer recharge. City Council approved a funding agreement for the
SWIP project on September 12, 2017 (Attachment J). Following completion of all
required permitting approvals construction is expected to begin in Spring 2019 and the
project is expected to be operational by late 2020.
21 of 28
Enhanced Reverse Osmosis (RO) Recovery
Staff is exploring the use of new technologies that could cost effectively increase the
production of the City’s existing Arcadia treatment plant by re -treating brine that is
currently discharged to the sewer. Current recovery rates for water processed through
the existing reverse osmosis treatment system stand at about 82%. In early 2018 , staff
will begin a feasibility study which includes a pilot test to assess the effectiveness of an
emerging technology which may increase the recovery rate to 90%, and possibly
beyond. Preliminary estimates are that an additional 672 AFY may be produced from
the brine currently being disposed. The feasibility study that would evaluate the
technology, costs, and water savings will be completed by the end of the fiscal year.
Numerical Groundwater Flow Modeling
In order to more effectively manage its groundwater resources, the City has completed
numerical flow modeling of its Olympic and Charnock well fields. Numerical
groundwater flow models are based on detailed hydrogeologic data which are compiled
into a sophisticated modeling software program that is used by numerous government
agencies and other municipalities throughout California. Once calibrated, flow models
can be used to identify and plan future groundwater development, better control
contamination plumes, and most importantly, provide for adaptive pumping that would
allow individual wells or entire supply fields to be better managed in order to sustainably
recharge without affecting the City’s overall groundwater production rates.
The US Geological Survey (USGS) has completed a detailed groundwater flow model
for most of the LA Basin. Staff has met with the USGS to begin the process of working
cooperatively to extend the USGS model into the Santa Monica Basin by sharing our
existing modeling with the agency. These activities would utilize the City’s currently
contracted modeling expert (ICF Engineers) to interface with the USGS modeling team.
Estimated costs for these activities over the next 12 months are approximately
$300,000. Work would initially focus on the Charnock and Olympic sub-basins. The
objective of the modeling program is to have a preliminary calibrated model for the sub -
basins the City currently pumps by 2020.
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Advanced Metering Infrastructure (AMI) Pilot – Smart Meters
AMI is an integrated system of smart meters, communications networks, and data
management systems that enables two-way communication between the water utility
and customers and provides real-time collection and evaluation of water use data.
Currently, water meters throughout the city are manually read once every two months.
This infrequent and staff intensive process provides very limited data regarding actual
water use patterns at individual sites and throughout the city. The real-time continuous
data provided by AMI allows for the timely identification of leaks and excessive water
use, allows customers to accurately budget their water use in order to meet
conservation goals, provides more accurate water billing, and can help to improve
customer service. In March of 2016 the City partnered with Southern California Gas
Company (SCG) and Aclara Technologies (Aclara) to run a proof of concept AMI pilot.
The pilot involved retrofitting some 200 City water meters (single family, multi-family,
commercial) and using SCG’s network infrastructure to transmit the meter reading data
to a network management database and software hosted by Aclara. Subsequently, an
additional 500 meters (roughly all City of Santa Monica municipal accounts and some
locations that were challenging for City crews to perform manual meter reads for billing)
were retrofitted with AMI technology. The pilot will run until March 2018.
Preliminary indications are that 99.2% of the hourly data transmitted from the meter to
the Data Management System has been received without error; the outlier may have
been signal interference at one of the SCG’s data collection units. During the pilot
active response to anomalies in the data received (high consumption alerts) have
allowed customers to be notified of potential leaks in time to reduce significant water
loss. The continuation of the pilot will address the effectiveness of those services with
both smart meters and a consumer engagement overlay called WaterSmart, which
helps customers manage their water usage and assists the City to comply with State
mandates. The full findings of the AMI pilot will be presented to Council in 2018 along
with recommendations for possible expansion of the AMI system to all Santa Monica
customers.
Summary of Next Steps
23 of 28
As previously noted in this report, staff initiated a comprehensive update of the
Sustainable Water Master Plan (SWMP) earlier this year. It is too soon to tell whether
the City will meet its water self-sufficiency goal by 2020. Significant progress has been
made on implementing and updating that plan, including completion of the preliminary
sustainable yield analysis (SYA) and integration of new projects such as SWIP, the
Clean Beaches Project and improvements in water treatment efficiencies. However,
additional work is required to validate the sustainable yield estimates, determine
availability and costs to access potential additional local groundwater resources, and
evaluate the cost and viability of additional water conservation programs as requested
by the Task Force on the Environment. As detailed above, the additional work required
to update the SWMP is currently underway and is expected to be completed in late
spring 2018. The results of that additional analysis will be incorporated into an updated
SWMP, which will be presented to Council in mid-2018 and will include a detailed
progress report and timeline for achieving the water self -sufficiency goal.
Upcoming Water Studies
Water/Wastewater Rate Study & new 5-year rate adjustment schedule (2020 to 2024)
The current rate schedule was approved in early 2015 and provides potential rate
adjustments for calendar years 2015 to 2019. Staff is preparing to begin a water and
wastewater rate study by midyear 2018 in order to bring rate recommendations to
Council in the fall of 2019.
Sustainable Groundwater Management Act (SGMA)
In May of 2017, Council approved a Memorandum of Understanding (MOU) and the
City’s participation in the formation of the Santa Monica Basin Groundwater
Sustainability Agency (SMBGSA). At approximately the same time, Los Angeles
County and the cities of Los Angeles, Beverly Hills, and Culver City also executed the
MOU to form the SMBGSA. After the required 90 -day posting period to allow public
review of the MOU, no challenges to the MOU were received and the SMBGSA was
designated the exclusive Groundwater Sustainability Agency (GSA) for the Santa
Monica Basin. Milestone deadlines for the SMBGSA now include:
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Preparation and submittal of a Groundwater Sustainability Plan (GSP) for the
basin, January 31, 2022
Following the adoption of the GSP, and annually thereafter, the GSA must submit
a GSP Monitoring Report, April 1, 2023
The GSP must include measurable objectives an d milestones in increments of 5
years to achieve sustainability within 20 years of GSP adoption, January 31,
2042
The SMBGSA has initiated monthly meetings, led by Santa Monica, to address moving
forward expeditiously to retain consultant(s) to assist with the preparation of the GSP,
as well as to identify necessary amendments to the MOU as they relate to the potential
development of bylaws and cost-sharing issues. Any amendments to the MOU agreed
upon unanimously by the member agencies will be brought to the respective agencies’
governing bodies for approval.
Task Force on the Environment and Water Advisory Committee Actions
Findings of the preliminary SYA, progress on the update to the Sustainable Water
Master Plan, and the Rate Adjustment recommendations were presented to the
Environmental Task Force on September 18, 2017 and October 16, 2017. The same
information was presented to the Water Advisory Committee on October 2, 2017, and
November 6, 2017. No action was taken by either body; however during discussions of
funding for sustainability projects, the Task Force passed the following two motions:
September 18, 2017
The City of Santa Monica Task Force on the Environment reinforces the position
that all of the water settlement funds should be used to help the City get to and
maintain water self-sufficiency and water perpetuity.
October 16, 2017
WHEREAS, there is $120 million from previous settlements.
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WHEREAS, Water Fund capital improvement program (CIP) projects are estimated at
$42 million over the next five years.
WHEREAS, the City is borrowing $56 million from the State of California to fund the
Sustainable Water Infrastructure Project (SWIP) to assist in achieving water self -
sufficiency by 2020. The total cost of the project is estimated at $69.9 million.
THEREFORE, the Santa Monica Task Force on the Environment strongly
supports the projects recommended by staff, but we are not currently
recommending the proposed rate increase.
With regard to the water settlement funds referenced in the motions from the Task
Force, staff prepared an information item dated December 19, 2017 (Attachment K),
which outlines the sources and uses of those funds and the remaining balance of
unrestricted funds that have been set aside in the General Fund to assist with funding of
other priority projects as identified by Council.
To date, Council has made the determination to use both pay-as-you-go and debt
financing to fund Sustainable Water Master Plan projects. The pay-as-you-go funding
comes from a combination of ratepayer-generated revenues and the $33.6 million
balance of MTBE settlement funds after the completion of remediation work at the
Charnock facility. These funds have been budgeted to pay for capital projects included
in the last Water Rate Study approved in February 2015. For Fiscal Years 2014-15
through 2018-19, capital projects included and will include general system
improvements such as emergency generator enhancements, water main replacements,
and treatment plant pressure vessel repair, among others. In September, 2017, the
City entered into an agreement with the State Water Resources Control Board to
receive a very low interest (1.8%), 30-year loan in the amount of $56.9 million, with $4
million in debt forgiveness, to fund the SWIP projects. With this loan, the City was able
to leverage funds at a lower rate than would be possible through other financing, and
the $4 million in principal forgiveness further lowered the price of the financing. In the
current economic climate, bond financing for lease revenue bonds or revenue bonds,
whether in the General Fund or enterprise funds, is approximately 4 -5%. As a result,
26 of 28
the use of a Clean Water State Revolving Fund (CWSRF) loan leveraged funds at a
lower price.
Staff proposed to transfer $11.1 million in FY 2017-18 from General Fund reserves for
the 2009 Gillette water mediation settlement funds to the Water Fund reserves in order
to cover ongoing and future costs for remediation of polluted groundwater in the
Olympic Well Field / Sub-basin. $6.5M would be reserved for annual ongoing
remediation costs for a ten-year period including monitoring, permitting and reporting
required by the State; and $4.6M would be reserved as a contingency for other Olympic
remediation-related costs.
The larger policy issue of the mix of financing between rate payer and water settlement
resources will be addressed in the upcoming Capital Improvement Plan adoption
process after the completion of the currently ongoing technical studies.
Financial Impacts and Budget Actions
1. FY 2016-17 water sales increased 2.5% versus FY 2015-16, slightly above the
2% increase projected by staff, resulting in sales revenue $379,440 greater than
budgeted. Although the State has discontinued its mandatory conservation
requirement, the City has remained at Stage 2 of its Water Shortage Response
Plan (mandatory 20% reduction versus 2013 levels) and implemented the Water
Neutrality Ordinance for new developments effective July 1, 2017. As of October
2017, FY 2017-18 water sales of 1,786,912 HCF are down by 1% versus the
same period in FY 2016-17 (1,807,373 HCF); therefore, staff projects water sales
to finish FY 2017-18 1% lower than FY 2016-17. Based on a 5% water rate
increase for calendar year 2018, increase revenue budget at account
25671.402310 in the amount of $161,660.
2. Approval of the recommended action requires the following FY 2017 -18 Capital
Improvement Program budget appropriations and reductions in the Water Fund:
Account Number Amount
27 of 28
C259078.589000 – Groundwater Management Plan $150,000
C259219.589000 – Arcadia Enhanced RO Recovery $250,000
C259220.589000 – Reservoir Improvements $900,000
C259223.589000 – DInSAR Study $100,000
C259224.589000 – City/USGS Numerical Flow Model $300,000
C250162.589000 – Water Resources Tenant Improvement ($450,018)
C259209.589000 – Arcadia Water Plant Membrane ($700,000)
Total $549,982
3. Approval of the recommended action requires a FY 2017 -18 Capital
Improvement Program budget reduction in the Wastewater Fund in account
C310162.589000 in the amount of $1,950,017.
4. Approval of the recommended action requires an interfund transfer of
$11,100,000 from Gillette-Boeing water mediation settlement funds in account
01695.570080 to the Water Fund in account 25695.570080. This also requires
a release of fund balance 1.380237 in the amount of $11,100,000.
Prepared By: Gil Borboa, Water Resources Manager
Approved
Forwarded to Council
Attachments:
A. February 24, 2015 Staff Report - Public Hearing to Adopt Water Rates
B. February 23, 2016 Staff Report - State of the Water Fund
C. November 22, 2016 Staff Report - State of the Water Fund
D. 2018 Proposed Water Rates
E. Water Fund Balance Projections - Two Rate Adjustment Options
F. Santa Monica Basin Preliminary Sustainable Yield Analysis - July 2017
28 of 28
G. July 11, 2017 Staff Report - Award Contract for Three Coastal Subbasin
Exploratory Borings/Wells and Replacement of Well SM-7
H. Santa Monica Basin DInSAR Report - September 2017
I. June 27, 2017 Staff Report - Award Construction Contract for Clean Beaches
Project
J. September 12, 2017 Staff Report - Authorizations for SWIP Funding and Owner's
Engineer Agreements
K. December 19, 2017 Information Item - Update on Water Mediation Settlement
Funds
L. Written Comments
M. Powerpoint Presentation
Attachment C: Summary of Water Self-Sufficiency Scenarios to Expand Local Groundwater Production
No. Description Conclusion Cost % of Self Sufficiency Achieved
(includes Conservation)
1. Expansion of Arcadia
WTP w/CCRO +
Separate Olympic
Pipeline and
Contamination
Treatment at Arcadia
WTP.
Best option
Maximizes local water supplies
$38M
+
$40MContaminaiton w/O&M
98-99%,
1-2% of imported water required
to maintain MWD connection for
emergencies
2. No contamination
treatment, acquisition of
new well
Not recommended as it would
not achieve self-sufficiency
goal and leave approximately
a 30% gap to be met with
purchasing imported water
Possible loss of 75%
production in Olympic Sub
Basin
Not recommended as it would
not achieve self-sufficiency
goal
$8M
~70%, limited production from
Olympic Sub-Basin due to
contamination
3. No contamination
treatment, pipeline and
additional wells
Not recommended as it would
not achieve self-sufficiency
goal
Possible loss of 75%
production in Olympic well field
Not recommended as it would
not achieve self-sufficiency
goal
$14M
~70%, limited production from
Olympic Sub-Basin due to
contamination
4. Airport Water Supply Not recommended as
additional studies is required
(e.g., increased risk due to
unknown water quality)
Not recommended at this time,
additional investigation
required to determine scope
~$50.5M
Unknown at this time (e.g., water
quality is unknown and if
treatment required for potential
contaminants)
5. Utilize existing Charnock
facility for contamination
treatment
Not recommended, pipeline
cost is cost prohibitive and
high O&M pumping cost
compared to Scenario 1
Not recommended due to
higher cost than other
scenarios,
$38M + $56M = $94M
98-99%,
1-2% of imported water required
to maintain MWD connection for
emergencies
No. Description Conclusion Cost % of Self Sufficiency Achieved
(includes Conservation)
6. Contamination
Treatment in Olympic
Median
Not recommended (e.g.,
construction staging, routine
O&M access, chemical
storage)
Aesthetics, scenic corridor,
chemical deliveries are not
practical
Not recommended (e.g.,
construction staging, routine
O&M access, chemical
storage)
$38M + $36M Contaminaiton
w/ O&M
98-99%,
1-2% of imported water required
to maintain MWD connection for
emergencies
7. Olympic Treatment Plant Cost prohibitive, need to
relocate and phase with other
projects
Not feasible due to high cost
$80-120M
98-99%,
1-2% of imported water required
to maintain MWD connection for
emergencies
Note: the percent self-sufficiency achieved includes contribution from the Optimal Conservation Plan and the scenario evaluated.
RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 BURBANK BLVD., SUITE 300, SHERMAN OAKS, CALIFORNIA 91401
SOUTHERN CALIFORNIA: (818) 506-0418 • NORTHERN CALIFORNIA: (707) 963-3914
WWW.RCSLADE.COM
UPDATED
PRELIMINARY STUDY
OF THE
SUSTAINABLE YIELD
OF THE GROUNDWATER SUBBASINS
WITHIN THE SANTA MONICA BASIN
LOS ANGELES COUNTY, CALIFORNIA
Prepared for:
The City of Santa Monica
Water Resources Division
1212 Fifth Street 3rd Floor
Santa Monica
CA 90401
Prepared by:
Richard C. Slade & Associates LLC
Consulting Groundwater Geologists
Sherman Oaks, California
Job No. 462-LASOC
June 2018
RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 BURBANK BLVD., SUITE 300, SHERMAN OAKS, CALIFORNIA 91401
SOUTHERN CALIFORNIA: (818) 506-0418 • NORTHERN CALIFORNIA: (707) 963-3914
WWW.RCSLADE.COM
UPDATED
PRELIMINARY STUDY
OF THE
SUSTAINABLE YIELD
OF THE GROUNDWATER SUBBASINS
WITHIN THE SANTA MONICA BASIN
LOS ANGELES COUNTY, CALIFORNIA
Prepared for:
The City of Santa Monica
Prepared by:
Richard C. Slade & Associates LLC
Consulting Groundwater Geologists
Studio City, California
Job No. 462-LASOC
June 2018
Earl F. LaPensee
Certified Hydrogeologist No. 134
Richard C. Slade
Professional Geologist No. 2998
TABLE OF CONTENTS
LIST OF ABBREVIATIONS/ACRONYMS USED IN REPORT ................................................... vi
EXECUTIVE SUMMARY ........................................................................................................... 1
SUSTAINABLE YIELD ......................................................................................................... 2
INTRODUCTION ....................................................................................................................... 5
BACKGROUND ................................................................................................................... 5
SUSTAINABLE GROUNDWATER MANAGEMENT ............................................................. 6
DISCUSSION OF “PERENNIAL YIELD,” “SAFE YIELD,” & “SUSTAINABILITY” TERMS .... 8
PREVIOUS SUSTAINABLE YIELD VALUES ....................................................................... 9
CALCULATION OF SUSTAINABLE YIELD .........................................................................10
Introduction ................................................................................................................... 10
Summary of Methods for Calculating Sustainable Yield ................................................ 14
FINDINGS ................................................................................................................................16
GROUNDWATER BASIN AND SUBBASIN BOUNDARIES ................................................16
GENERAL GEOLOGIC/HYDROGEOLOGIC CONDITIONS ...............................................17
Water-Bearing Sediments ............................................................................................. 18
Recent (Holocene) Alluvium ...............................................................................18
Lakewood Formation .........................................................................................18
San Pedro Formation .........................................................................................18
Non-water-Bearing Rocks ............................................................................................. 19
Geologic Structures ....................................................................................................... 20
WATERSHED AREA ...........................................................................................................22
NATURAL RECHARGE ......................................................................................................23
ARTIFICIAL RECHARGE AND CONSERVATION ..............................................................25
Introduction ................................................................................................................... 25
Sustainable Water Master Plan ..................................................................................... 26
Water Neutrality Ordinance ................................................................................26
Water Efficient Landscape and Irrigation Standards ...........................................27
HYDROLOGIC BASELINE CONDITIONS ...........................................................................27
Rainfall Totals ............................................................................................................... 27
Accumulated Departure of Rainfall ................................................................................ 28
Selection of Baseline Hydrologic Period ........................................................................ 29
GROUNDWATER WITHDRAWALS ....................................................................................30
Withdrawals by the City ................................................................................................. 30
Groundwater Withdrawals by Others ............................................................................. 32
WATER LEVELS .................................................................................................................34
Water Level Hydrographs .............................................................................................. 34
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
-iv-
Water Level Hydrographs – “Key” Well Concept ........................................................... 38
Arcadia Subbasin Key Well Hydrograph ............................................................38
Charnock Subbasin Key Well Hydrograph .........................................................39
Olympic Subbasin Key Well Hydrograph ............................................................40
Coastal Subbasin Key Well Hydrographs ...........................................................41
Crestal Subbasin Key Well Hydrograph .............................................................42
GROUNDWATER IN STORAGE .........................................................................................43
Storage Subunits and Parameters ................................................................................. 43
Calculation of Groundwater in Storage .......................................................................... 44
SUBUNIT/SUBBASIN CHANGES IN GROUNDWATER IN STORAGE CALCULATIONS ..45
Change in Groundwater Storage ................................................................................... 45
Arcadia Groundwater Storage Subunit/Subbasin ...............................................45
Charnock Groundwater Storage Subunit/Subbasin ............................................46
Olympic Groundwater Storage Subunit/Subbasin ..............................................47
Coastal Groundwater Storage Subunit/Subbasin ...............................................48
PRELIMINARY CALCULATIONS OF SUSTAINABLE (PERENNIAL) YIELDS ....................49
DISCUSSION OF HISTORICAL VALUES BY OTHERS .....................................................50
Comparison of Sustainable Yield Values ....................................................................... 50
Arcadia Subbasin .......................................................................................................... 51
Charnock Subbasin ....................................................................................................... 52
Olympic Subbasin ......................................................................................................... 54
FUTURE PLANNED WITHDRAWALS AND INJECTION ....................................................55
EVALUATION OF RAINFALL RECHARGE TO THE SANTA MONICA BASIN ...................56
CONCLUSIONS & RECOMMENDATIONS ...............................................................................57
REFERENCES REVIEWED ......................................................................................................60
APPENDIX 1 –FIGURES
Figure 1 -Location Map of Study Area
Figure 2 -Map of DWR Groundwater Basins
Figure 3A -Groundwater Subbasin Boundary Map
Figure 3B -Well Location Map
Figure 4A -Generalized Geologic Map of the Santa Monica Area
Figure 4B -Generalized Geologic Map Legend & Symbols
Figure 5 -General Stratigraphic Section for the Coastal Plain of Los Angeles County
Figure 6 -Map of Watershed and Local Drainages
Figure 7 -Groundwater Elevation Contours of the West Coast & Central Groundwater Basins
Figure 8A -Annual Rainfall Totals, Various Rain Gages
Figure 8B -Accumulated Departure of Rainfall
Figure 9 -Selected Baseline Period
Figure 10A -Arcadia Wellfield/Subbasin Hydrographs
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
-v-
Figure 10B -Charnock Wellfield/Subbasin Hydrographs
Figure 10C -Olympic Wellfield/Subbasin Hydrographs
Figure 11A -Key Well Hydrograph, Santa Monica Well No. 5, Arcadia Subbasin,
Total Change in Storage
Figure 11B -Key Well Hydrograph, Charnock Well Nos. 16 & No. 20, Charnock Subbasin,
Total Change in Storage
Figure 11C - Key Well Hydrograph, Santa Monica Well No. 7, Olympic Subbasin,
Total Change in Storage
Figure 12 -Usable Area of Groundwater Storage Subunits
APPENDIX 2 – TABLES
Table 1 -Summary of Well Construction Data for Historic and Existing City Wells Used in this
Study
Table 2 -Groundwater Production by City Wells and Other Wells (1988 through 2017)
Table 3 -Preliminary Calculations of Change in Groundwater in Storage During Baseline Period
for the Arcadia, Charnock and Olympic Groundwater Subbasins
Table 4 -Preliminary Calculations of Sustainable Yield, Santa Monica Subbasins
Table 5 -Comparison of Sustainable Yield Values, Santa Monica Subbasins
Table 6
Table 7 -Potential Sustainable Yield Values, Santa Monica Subbasins
Potential Lower and Upper Sustainable Yield Values, Santa Monica Subbasins
APPENDIX 3 – ICF May 25, 2018 Memorandum
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
-vi-
LIST OF ABBREVIATIONS/ACRONYMS USED IN REPORT
The following provides a list of abbreviations that may be used more than once throughout this
report and is provided for the convenience of the reader.
Abbreviation Description
AF acre-feet
AFY acre-feet per year
b symbol used for saturated aquifer thickness in an equation
BCC Brentwood Country Club
brp below reference point
bgs below ground surface
Cl Chloride
DWR California Department of Water Resources
GRA Groundwater Resources Association
GSP Groundwater Sustainability Plan
KJC Kennedy/Jenks Consultants
LACC Los Angeles Country Club
LADWP City of Los Angeles Department of Water and Power
LACFCD Los Angeles County Flood Control District
msl mean sea level
MWD Metropolitan Water District of Southern California
PGC Penmar Golf Club
PWL(s)pumping water level(s)
RCC Riviera Country Club
RCS Richard C. Slade & Associates LLC, Consulting Groundwater Geologists
RWQCB-LA Regional Water Quality Control Board – Los Angeles Region
S storativity (storage coefficient of an aquifer)
Sgw groundwater in storage
ΔS change in water levels for the baseline period
SS Specific Storage
Sy specific yield
SBBM San Bernardino Baseline and Meridian
SGMA Sustainable Groundwater Management Act
SMGB Santa Monica Groundwater Basin
SMURRF Santa Monica Urban Runoff Recycling Facility
SWL(s) Static water level(s)
TDS Total Dissolved Solids
ULARA Upper Los Angeles River Area
WCB West Coast Groundwater Basin
WRCC Western Regional Climate Center
Measurements/Units Abbreviations
gpd gallons per day;gpm =gallons per minute
gpm/ft ddn gpm per foot of drawdown; gpy = gallons per year
mg/L milligrams per Liter; µg/L = micrograms per liter
sq mi square miles
EXECUTIVE SUMMARY
INTRODUCTION
In support of the City of Santa Monica’s (City) efforts to achieve water self-sufficiency, the City
has retained Richard C. Slade & Associates LLC, Consulting Groundwater Geologists (RCS) to
assess the sustainable yield of the five subbasins within the Santa Monica Groundwater Basin
(SMGB). These groundwater subbasins, as identified by others, include the Arcadia, Charnock,
Coastal, Crestal, and Olympic subbasins. The City currently has active water wells and pumps
groundwater from three of these five subbasins, namely the Arcadia, Charnock and Olympic
subbasins. In addition, the City has recently completed a new water supply well (Airport No. 1)
in the Coastal subbasin at a location at the City’s Santa Monica Airport. The City plans up to two
additional wells at the Airport and is currently in the process of permitting the new well for use
as drinking water supply. The City has never had any water-supply wells in the fifth subbasin in
the SMGB, the Crestal subbasin.
The assessment of the quantity and extent of groundwater in the subsurface and the amount
of water that can be sustainably extracted for use is dependent on the understanding and
monitoring of a myriad of complex natural system factors, none of which can be determined
with absolute certainty. This is because all of these systems are interrelated in some fashion
and most transitory through time. The RCS calculations herein for the changes in groundwater
in storage for the three subbasins in the Santa Monica Groundwater Basin for which key data
are available, are therefore a conservative estimate that will change through time based on the
vagaries of climate, geology, natural and artificial recharge, well location and pumping by the
City and existing/future third parties. Refining these calculations will be an ongoing exercise that
will typically require the latest climate information, water level data, groundwater withdrawal data
and subsurface geologic information.
In this current update, the potential sustainable yield of the Olympic, Charnock and Coastal
subbasins of the SMGB have been revised, based on data from wells and exploratory borings
recently constructed in these subbasins by the City. Thus, this updated report contains the
information and data presented in the previous July 2017 report, along with additional data for
2017 regarding rainfall, geology, static water levels in key wells, and groundwater withdrawals
from active City wells and known private pumpers. Further in 2017, in addition to the new
Airport No.1 well, the City also successfully completed a new municipal-supply well (Santa
Monica No. 8, SM-8) in the Olympic subbasin. This well is a replacement for the defective
Santa Monica Well No. 7 (SM-7), which was destroyed following completion of SM-8. As part of
the City’s recent exploratory drilling program a third location, at the City’s Colorado Maintenance
Yard, was completed as a new groundwater monitoring well in the Coastal subbasin. It should
be noted that because these wells have been only recently constructed, no long-term water
level data have been generated and such data remains to be collected and evaluated later.
Because our evaluations and conclusions presented in this report are based on newly-acquired
data, this Updated report supersedes any/all versions generated prior to the date of this current
report.
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SUSTAINABLE YIELD
Sustainable yield of an aquifer or basin is currently accepted to mean the rate at which
groundwater can be withdrawn (pumped) on a perennial basis under specified operating
conditions without producing an undesired result. Such undesirable results can include, among
other things, the unsustainable reduction of the water resource, degradation of water quality
(e.g., salt water intrusion), land subsidence, and uneconomic pumping conditions. The pumpage
and change-in-storage method has been used in this evaluation to calculate the sustainable
yield values herein. This method basically involves determining the change in static water levels
(SWLs) in key water wells and computing the related change in the groundwater in storage,
over a representative period of precipitation, known as a hydrologic baseline period; and then
deriving an estimated sustainable yield from known annual groundwater withdrawal data that
induced those water level changes. The net change in groundwater in storage occurring
between the beginning and the end of this selected base period was determined and an
average annual change in storage was calculated. The long-term average annual sustainable
yield represents the algebraic sum of the calculated values of average annual withdrawals by
pumping and average annual storage change for each subbasin.
Storativity is defined as the amount of water an aquifer releases from or takes into storage per
unit surface area of the aquifer per unit of change in head. Groundwater in storage was
calculated using the ground surface area of each groundwater subbasin, the estimated specific
yield of the aquifer(s) in which the existing water wells are perforated, and the average
thickness of the aquifer systems in each respective subbasin.
A 30-year baseline period from 1988 through 2017 was established to help determine and
update sustainable yield values, based on more current hydrologic and hydrogeologic data.
Because the City did not pump for several years in the Arcadia Subbasin (4 years) and the
Charnock subbasin (13 years), this rendered a level of complexity to the calculation of changes
in groundwater in storage in these subbasins for a 30-year baseline period. To overcome this
complexity, the change in groundwater in aquifer storage (ΔS) was calculated by assessing a
split baseline period in the Arcadia and Charnock subbasins because of the years during which
the City did not extract any groundwater from these two subbasins. City wells in the Olympic
subbasin were continuously pumped over the entire baseline period and hence, there was no
need to split the baseline period for this subbasin
Thus, updated average subbasin withdrawals by the City over the 30-year baseline period are
as follows:
o Arcadia subbasin
440 AFY (wellfield shutdown, and hence no pumping in 4 out of those 30 years)
o Charnock subbasin
6,290 AFY (wellfield shutdown, and hence no pumping in 13 out of those 30 years)
o Olympic subbasin
1,860 AFY (continuously pumping during the entire 30-year baseline period)
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For comparison, when the recent subbasin withdrawals solely for the 5-year period from 2013
through 2017 are assessed, the average volumes of groundwater pumped solely by the City
were:
o Arcadia subbasin: 635 AFY
o Charnock subbasin: 8,042 AFY
o Olympic subbasin: 1,775 AFY
In addition to City withdrawals, there are two golf courses in the Arcadia subbasin, and one golf
course in the Crestal subbasin that pump groundwater for irrigation purposes. When these
private golf course groundwater withdrawals are included (a total of approximately 570 AFY
combined for the two courses in the Arcadia subbasin) the total groundwater withdrawals from
the Arcadia subbasin are estimated be on the order of 1,010 AFY over the 30-year baseline
period, and approximately 1,200 AFY over the last five years. Potential pumpage by the golf
course in the Crestal subbasin is unknown, but could be expected to be on the same order as
the other two courses. Taking these withdrawals into account, total combined average annual
withdrawals from the three above-listed subbasins has been approximately 9,200 AFY over the
extended 30 year baseline period.
The City plans to construct two additional municipal-supply wells in the Coastal subbasin not far
from the recently completed Airport No. 1 well. Combined, these three wells would theoretically
be able to produce a minimum of approximately 1,450 AFY. In addition, the City is planning to
purchase another water-supply well in the Charnock subbasin from a third party. This well
reportedly has the capacity to produce another 1,450-1,610 AFY. In the Olympic subbasin, the
City is planning to replace a poorly performing well (SM-3), which also has casing problems.
When completed this new replacement well is expected to produce approximately 1,368 AFY,
which is roughly 360 AF greater than the current supply capacity from the deficient SM-3. The
City also plans to bring the new SM-8 well online within the next year. This well replaced SM-7,
which has casing problems and was never placed into active production. SM-8 is expected to
produce 970 AFY of additional water. Perhaps more importantly, the City is scheduled to begin
construction in 2019 on the Sustainable Water Infrastructure Project (SWIP). The SWIP will
harvest and treat non-conventional water resources such as runoff, brackish groundwater and
municipal wastewater for beneficial conjunctive reuse. When completed, and properly permitted,
the SWIP is expected to provide approximately 1,100 AFY of highly treated water for aquifer
recharge in the Olympic subbasin, further enhancing the long-term yield of this important
subbasin.
Based on the planned water supply improvements discussed above and the total amounts
extracted from the three subbasins, and the calculated change in groundwater storage, RCS
was able to determine estimated ranges of the sustainable yield for each of the four
groundwater subbasins in which the City has water supply wells.
The following table lists: the current estimated yields based on the pumping and change in
storage method described elsewhere in this report; the ranges of possible sustainable yield if
additional factors such as new wells; storativity in confined aquifers (which is generally higher
than that of unconfined aquifers); and mountain front recharge were considered; and previous
estimates of sustainable yield values for those portions of the subbasins currently subject to
pumping by the City. As noted earlier, the City has never owned or operated any municipal-
supply wells in the Crestal subbasin. The estimates below also assume that City wells are
pumped on a continuous operational mode (i.e. 24hours per day annually).
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GROUNDWATER
SUBBASIN
ESTIMATED
SUSTAINABLE YIELDS
(AFY)
PREVIOUSLY
CALCULATED
SUSTAINABLE
YIELD
(AFY)
Arcadia 870 to 920 2,000
Charnock 6,410 to 8,080 4,420 to 8,200
Olympic 2,360 to 3,145 3,275
Coastal 1,160 to 1,450 4,225
Crestal Yet to be Determined 2,000
Subtotal 10,800 to 13,595 15,920 to 19,700
Recharge Value 1,000 to 1,130 NA
Total 11,800 to 14,725 NA
Note: Data from one private golf course in the Crestal subbasin are not included in the above table. The
Recharge Factor is a conservative percentage of the estimated annual natural recharge to the SMGB from
adjacent and distal mountain front areas derived from USGS data.
The potential for limitations on future groundwater withdrawals from the City’s active subbasins
presented by the estimated sustainable yields indicates that the City’s approach of replacing
underperforming wells, investigating additional water supply in the Coastal subbasin and the
pursuit of nonconventional resources and indirect potable reuse via aquifer recharge from its
planned SWIP are both prudent and necessary for the City to achieve and sustain its long-term
objective of independence from environmentally-costly imported water. Importantly, it is
recommended that the City continues its heretofore successful water conservation programs,
pursues the acquisition of the third party well in the Charnock subbasin, and expedites the
further assessment of the Coastal subbasin. Identification of additional viable groundwater
reserves in the Coastal subbasin will help alleviate the current heavy reliance on the three
subbasins currently providing groundwater supply and could facilitate the implementation of
adaptive pumping measures where individual wells or wellfields could be periodically rested to
allow for natural recharge.
Based on detailed modeling work conducted jointly by the USGS and the Water Replenishment
District of Southern California (2016), and a recent Technical Memorandum prepared by ICF
Consulting on behalf of the City (2018), potential recharge to the SMGB via rainfall and
underflow in the subsurface from adjacent and more distal mountain front area was estimated to
range from 12,131 to 12,722 AFY. Assuming a conservative estimate of 8% of the total amount
of annual recharge estimated by the USGS and ICF reports is available to augment basin
recharge from local precipitation volumes, then a supplemental recharge factor of 1,000 to
1,130 AFY could conceivably be applied to the currently-calculated sustainable yield, providing
a potential upper sustainable value of 11,800 to 14,725 AFY for the City’s four primary
groundwater subbasins (see table above).The City has engaged Earth Consultants
International (ECI) to further assess pathways for basin recharge from mountain front areas
utilizing innovative approaches such as Differential Interferometer Synthetic Aperture Radar
(DInSAR) data generated by satellite-based platforms.
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INTRODUCTION
BACKGROUND
The City of Santa Monica (City) is a general law city, incorporated in November 1886, and is
authorized to engage in the provision of water service to its residents and customers, pursuant
to California Water Code Section 38730 et seq; it is a “local agency,” as defined in California
Water Code Section 10753(a). The City provides retail water service through the operation of
its City-owned Water Resources Division and its associated groundwater production and
treatment facilities that are located both within the City and within proximal areas that lie within
the adjoining City of Los Angeles. The City Water Resources Division is currently the sole
municipal-supply producer of groundwater from the SMGB; which covers approximately 50
square miles, and underlies and extends beyond the entire 8.3 square mile boundary of the City
of Santa Monica. The City’s water system serves a resident population of around 93,834 via
17,847 connections. The City’s residential population is projected to grow by approximately
1.6% per annum through 2030. Considered a world class tourist destination, the City’s visitors
can swell the residential population daily by 100,000 persons or more, particularly during the
summer months.
As a charter member of the Metropolitan Water District of Southern California (MWD), the City is
currently purchasing imported water to augment its local supply. Recent data from 2017 shows
the City imports around 25 to 30% of its supply, with the remainder coming from local
groundwater. For the long term, the City is committed to eliminating its dependence on
imported water. The City seeks to achieve this objective through continued community
engagement and water conservation, the sustainable pumping of its local aquifers, and the
treatment and reuse of other non-conventional water resources, such as brackish groundwater,
dry weather and storm-water runoff, and treated municipal wastewater. Part of this effort which
the City is pursuing at present is to site, design and construct additional municipal-supply water
wells in certain of the local groundwater subbasins. As an additional element of the City’s effort
to reduce its dependence on imported MWD water, the City is implementing an ongoing
program of sustainable groundwater management in conformance with California’s Sustainable
Groundwater Management Act (SGMA) of 2014. Towards this goal Santa Monica is the lead
agency in the newly-created Santa Monica Basin Groundwater Sustainable Yield Agency
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(SMGBSA). The SMBGSA comprises the Cities of Santa Monica, Los Angeles, Beverly Hills,
Culver City, and Los Angeles County.
SUSTAINABLE GROUNDWATER MANAGEMENT
In 2014, and in part as a response to State-wide drought conditions commencing around 2010,
the State Legislature passed SGMA legislation. Generally, and as described by the California
Department of Water Resources (DWR), this act “…empowers local agencies to adopt
groundwater management plans that are tailored to the resources and needs of their
communities. Good groundwater management will provide a buffer against drought and climate
change, and contribute to reliable water supplies regardless of weather patterns. California
depends on groundwater for a major portion of its annual water supply, and sustainable
groundwater management is essential to a reliable and resilient water system” (DWR, Website
2017 at http://www.water.ca.gov/cagroundwater/).
In accordance with SGMA, both the DWR and the State Water Resources Control Board
(SWRCB) have been given the responsibility of developing regulations and reporting
requirements needed to carry out SGMA for all groundwater basins in the State, except those in
which pumping rights have been determined by the courts (i.e., in adjudicated groundwater
basins). The DWR has been tasked to determine boundaries of the numerous groundwater
basins in the State, to establish a priority ranking of those basins (in terms of such items as total
groundwater withdrawals, water level trends, and possible “overdraft”), and to develop
regulations for groundwater sustainability. The SWRCB has been tasked to set fee schedules,
data reporting requirements, probationary designations, and interim sustainability plans for the
basins.
To carry out its duties about SGMA, the DWR has consequently established a program to
implement the provisions of the act. To this end, the DWR has set out five basic objectives of
that program, namely:
o Develop regulations to revise groundwater basin boundaries.
o Adopt regulations for evaluating and implementing Groundwater Sustainability Plans
(GSPs) and coordination agreements.
o Identify basins subject to critical conditions of overdraft.
o Identify water available for groundwater replenishment.
o Publish best management practices for the sustainable management of groundwater.
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Recently, the DWR has adopted a Draft Strategic Plan (DWR, 2015) to help achieve those five
stated objectives. In its Draft Strategic Plan, the DWR outlined the following elements that the
plan will attempt to accomplish:
o A description of current groundwater conditions in the State, demonstrating the
unsustainable nature of current management practices and framing the need for
action.
o The identification of legislation and other drivers of policy. This includes the SGMA,
the California Water Action Plan, and the Proposition 1 Water Bond.
o The identification of “success factors” in addressing the key challenges facing
groundwater management in the State.
o Description of the goals and objectives of the plan necessary for program
implementation and DWR actions to address these items.
o Presentation of an initial plan for the DWR regarding communication and outreach to
partnering, regional and local agencies, stakeholders, and the public.
In the 2015 Draft Strategic Plan (p.5), the DWR cited recent groundwater conditions regarding
declines of water levels in many groundwater basins in the State and especially those prone to
large-volume withdrawals in support of agriculture. According to the DWR, factors leading to
declines in water levels include:
o “Chronic long-term pumping of groundwater more than the safe yield of the
groundwater basin. Population growth, expansion of agricultural practices, allocation
of water to environmental resources and restrictions to protect threatened species all
have contributed to either increased water demand or decreased availability of
surface water supplies in California. In response, many water users pump
groundwater to offset the reduction in surface water supply.”
o “Short-term increase in groundwater pumping in drought years. Drought conditions
in the last three years have exacerbated the groundwater conditions in many basins
as more people use groundwater to meet their needs.”
o “Changes in irrigated land use. During the last two decades, more agricultural lands
have been converted from annual crops to permanent crops, such as vine, nuts, and
fruit trees, resulting in water demand hardening. Permanent crops require irrigation
during the drought, while in the past many acres of annual crops were left idle
through drought years.”
o “Climate change, resulting in reduced snowpack, will exacerbate the water supply
and demand imbalance.”
SGMA was promulgated for defined groundwater basins in the State, as shown and described
in DWR Bulletin 118 (1975, and its 2003, 2004, 2013 and 2016 updates). Under SGMA, the
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“DWR was to consider, to the extent available, all of the data components” needed for
prioritization of the groundwater basins. DWR is to consider the following elements:
1. “Population overlying the basin”.
2. “Rate of current and projected growth of the population overlying the basin”.
3. “Number of public supply wells that draw from the basin”.
4. “Total number of wells that draw from the basin”.
5. “Irrigated acreage overlying the basin”.
6. “The degree to which persons overlying the basin rely on groundwater as their
primary source of water”.
7. “Any documented impacts on the groundwater within the basin, including overdraft,
subsidence, saline intrusion, and other water quality degradation”.
8. “Any other information determined to be relevant by DWR”.
This current study attempts to address Item Nos. 3, 4, and part of Item No. 7, regarding impacts
of pumpage on groundwater in the subbasins within the SMGB. The focus of this current RCS
report is, thus, on changes in groundwater levels over time in the local subbasins for which
adequate data are available.
DISCUSSION OF “PERENNIAL YIELD,” “SAFE YIELD,” & “SUSTAINABILITY” TERMS
Estimates of the “safe yield” or “perennial yield” of the individual subbasins within the SMGB
have been generated for the City by prior investigations. This current study is an attempt to
help establish updated values for the perennial (or sustainable) yield, so that the City can
determine, for purposes of future planning, the approximate amounts (i.e., volumes) of
groundwater that can be pumped on a sustainable basis from each of its local groundwater
subbasins, without inducing a negative impact on the groundwater resources within those
subbasins for which a sustainable yield can be determined at this time.
The term “safe yield” of a groundwater basin was originally defined as the “rate at which water
can be withdrawn from an aquifer for human use without depleting the supply to such an extent
that withdrawal at this rate is no longer economically feasible” (Meinzer, 1923). Later, other
studies, like Todd (1959, p. 363), noted that the term “safe yield” has been taken by some
investigators to imply a “fixed quantity of extractable water [that is] limited to the average annual
basin recharge”. In our professional opinion, the term “safe yield”, if used, should be restricted,
strictly to those groundwater basins for which the pumping rights have been adjudicated by the
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courts. The SMGB has not been adjudicated. An example of a nearby region which has
previously been adjudicated by the courts, and where the term “safe yield” is used, is the nearby
Upper Los Angeles River Area (ULARA). In this current RCS report, the term “sustainable
yield,” rather than “safe yield” or “perennial yield” shall be used.
Todd (1959, p. 363) also defined the term “perennial yield” as the “rate at which water can be
withdrawn perennially under specified operating conditions without producing an undesired
result”. Such undesired results listed by Todd included:
a) Progressive reduction of the water resource.
b) Development of uneconomic pumping conditions.
c) Degradation of groundwater quality.
d) Interference with water rights.
e) Land subsidence caused by lowered groundwater levels.
Thus, the term “perennial yield” generally refers to a condition that is dependent upon changing
groundwater conditions, of which reduction of the groundwater supply and degradation of the
groundwater quality in any groundwater basin would be important issues. In essence,
“perennial yield” can be considered a dynamic value, which can change under varying
conditions of groundwater withdrawals and rainfall recharge.
More recently, the term “sustainable yield” has come into the vernacular as related to
groundwater resource potential and supply. Sustainable yield as defined by the DWR is “the
maximum quantity of water, calculated over a base period representative of long-term
conditions in the basin and including any temporary surplus, that can be withdrawn annually
from a groundwater supply without causing an undesirable result” (DWR, 2017, Sustainable
Groundwater Management Act website). Thus, such a definition appears synonymous with the
slightly older term “perennial yield,” and this current study has been conducted in general
accordance with methods that are used to conduct typical “perennial yield” studies. As
previously stated, RCS shall use the term “sustainable yield” in the current study to reflect the
change to this more commonly accepted term for “perennial yield.”
PREVIOUS SUSTAINABLE YIELD VALUES
In an Updated Draft Memorandum (dated March 27, 2013), prepared by RCS for Kennedy
Jenks Consultants (KJC) and the City, an initial review was performed of historic reports that
had presented sustainable yield values for the subbasins within the SMGB. That 2013-dated
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RCS document was utilized by the City as a potential starting point for water resource supply
and planning purposes. Specifically, in that Memorandum, RCS tabulated sustainable yield
values that had been estimated in previous studies of the groundwater subbasins, as follows:
Groundwater
Subbasin
Sustainable Yield Value by Others
(AFY)
Arcadia 2,000
Charnock 4,420 to 8,200
Olympic 3,275
Coastal 4,225
Crestal 2,000
Total 15,920 to 19,700
Further refinement of those previous values, to the extent permitted by currently available data,
was an important objective of this current study.
CALCULATION OF SUSTAINABLE YIELD
Introduction
RCS (1986) cited typical methods of determining the perennial (or sustained) yield of an aquifer
system(s) in a groundwater basin. The traditional or classical assessment of sustainable yield is
based on evaluation of the key factors of the basic hydrologic water balance equation, where
the movement, flows and quantities of groundwater are governed by the equation: Inflow-
Outflow = Change in Storage (ΔS). The hydrologic water balance equation is controlled by
several variables, as shown in the following equation:
Surface water recharge (via percolation of rainfall and stream flows and imported water)
+ Groundwater underflow + Decreases in surface water and groundwater in storage =
Surface water discharges + Groundwater outflows + Consumptive use + Export of water
from the basin + Increase in surface water storage + Increase in groundwater in storage.
Inflow into a groundwater basin typically consists of: groundwater underflow from upgradient
groundwater basins and from adjoining hill and mountain areas; deep percolation of surface
water runoff; infiltration of rainfall directly on the ground surface; deep percolation of water in
artificial spreading basins; deep percolation of excess irrigation (irrigation return); and direct
injection of water into the subsurface. Outflow from a groundwater body typically consists of:
subsurface outflow; groundwater extractions by water wells; and spring flow and
evapotranspiration of shallow groundwater. When inflow is greater than outflow, the amount of
groundwater in storage will increase (and groundwater levels will rise). Conversely, when
outflow is greater than inflow, the volume of groundwater stored in the aquifer systems will
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decrease (and water levels will decline). Thus, if outflow (e.g., pumping from wells) exceeds
inflow over time, then water levels will show a gradual decline over time (a decline in ΔS). Such
a reduction in groundwater in storage necessitates better management of the groundwater uses
to help stabilize water levels whereby water level declines may be reversed to a more stable
condition (i.e., no ΔS over time).
The individual data components of the traditional water balance solution of sustainable yield
consist of the following:
Specific Inflow elements (recharge) include:
1. Deep percolation of rainfall.
2. Infiltration runoff in rivers, streams and creeks.
3. Deep percolation at spreading basins.
4. Direct use of recharge wells.
5. Deep percolation of imported water (i.e., spreading basins).
6. Groundwater underflow from adjacent basins.
7. Irrigation returns.
Specific Outflow elements (discharge) include:
1. Surface outflow from streams and creeks.
2. Groundwater outflow.
3. Springs (direct surface outflow).
4. Evapotranspiration.
5. Pumpage from wells.
6. Sewer and storm drain system discharges from basin.
7. Export of water resources to another basin.
In the development of a sustainable yield “model” for the SMGB, the following specific elements
could be considered for each subbasin for which the required data are available:
1. Selection of an appropriate baseline period for data, based on precipitation records.
2. Collection of available data for wells, such as water levels, representative withdrawals,
etc.
3. Calculating groundwater in storage.
4. Calculating the inflows into each subbasin.
a. Groundwater underflow.
b. Estimates of direct recharge via precipitation.
c. Estimates of recharge from surface water runoff and excess irrigation.
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d. Estimates of returns from excess irrigation, and from possible subsurface
sewage disposal.
e. Annual volumes of imported water.
5. Calculation of outflows from the basin:
a. Pumpage from City wells.
b. Flow from University High School Springs
c. Stream gages (not available for SMGB, thus flows can only be grossly
estimated).
d. Estimated irrigated areas and potential evapotranspiration.
e. Groundwater underflows (e.g., flow of springs/seeps into ocean);
groundwater flow directions and gradients in each subbasin are required.
f. Per capita/household use of water.
g. Amounts of local water exported to the Hyperion Treatment Plant.
However, Bredehoeft et al (1982) noted that there is a common misconception among water
resources managers about determining the water balance of an area and that certain basic
hydrologic principles are being overlooked. Those investigators approached their re-
examination of the issue on a purely mathematical basis. They cite that computation of the
average water level drawdown can be done through the following basic equation, assuming a
water table or unconfined aquifer system:
S = ΔV/(Sy*A)
Where: S = the basin-wide average drawdown.
ΔV = the volume removed from storage (discharged and/or “captured”)
Sy = the specific yield of the sediments (i.e., that amount of water that can be
removed from storage by gravity).
A = the area of the basin
Because groundwater in the aquifer systems of the SMGB might be under different
hydrogeologic conditions (e.g., unconfined, semi-confined or confined), it is recognized that
estimates of sustainable yield derived by utilizing the change in storage method could be
conservative and that additional compensating factors would need to be considered. An
example of one such factor could be the increase in volume of water following release
(pumping) of groundwater in storage under confined conditions. However, such an increase in
volume could also be relatively minor, compared to total volumes pumped.
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Regarding conducting a traditional water balance analysis of the SMGB, historic and current
data for each of the items described in the text above were, until recently, generally lacking for
the subbasins of the SMGB. However, in 2017 the City began an integrated hydrogeologic data
acquisition program that, when fully realized, will allow for transition towards a more traditional
water balance analysis in future biennial updates to the sustainable yield of the SMGB
subbasins for the purpose of comparing and planning future aquifer management strategies.
The results of this current updated study are based primarily on pumpage and change in
groundwater in storage, and include a discussion of SMGB recharge from a separate study in
2018 conducted by ICF Corporation (ICF).
In this study, only the physical aspects of groundwater in the aquifer systems have been
evaluated, in terms of the potential pumping that could be conducted over the long term without
permanently lowering groundwater levels in the local subbasins. Compensating factors include
new hydrogeologic data collected by the City and potential recharge to the SMBG from areas
previously not considered, such as adjacent and distal mountain front areas. Groundwater
quality, another factor to consider that could impact the supply of potable water to the City, is
not addressed in this report, because the City is currently treating its pumped groundwater to
comply with existing State and Federal regulations in terms of the established Maximum
Contaminant Levels (MCLs) that exist for certain constituents in raw groundwater and drinking
water. Also, not addressed in this updated report are water rights, primarily because pumping
rights in the SMGB have not been adjudicated by the courts, although the City has long been
the only significant pumper in the SMGB.
Potential land subsidence caused by historic or future pumping is not within the expertise of
RCS and therefore is not addressed. However, anticipating this concern, the City has
commissioned a separate satellite-based Differential Interferometer Synthetic Aperture Radar
(DInSAR) study to assess various subbasin characteristics, including subsidence. DInSAR
technology is capable of detecting minute changes in surface topography caused by
groundwater withdrawal, geologic faulting and other natural and anthropogenic forces. A
DInSAR study conducted in 2017 by Earth Consultants International (ECI) concluded there were
no indications of basin-wide subsidence due to groundwater withdrawal. A supplemental
DInSAR study is currently being conducted by the City to assess for potential seasonal near
surface pathways for basin recharge from mountain-front areas adjacent to, and possibly distal
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from, the SMGB. The City is also in the process of working with recognized climate change
experts to define a scope of work for conducting climate change stress-tests of its biennial
updates to its sustainable yield analysis and conservation programs in order to assist in the
adaptive management of all its water resources, and to aid in water related capital improvement
project planning and construction.
Summary of Methods for Calculating Sustainable Yield
The pumping and change-in-storage method basically involves deriving sustainable yield from
pumpage data and from the change in the volume of groundwater in storage, over a
representative period of precipitation and water well operations. To employ this method, the
geology of the groundwater basin must be well defined, as to the areal extent and thickness of
the water-bearing deposits, and the average specific yield (i.e. related to porosity and
permeability) of those materials. After the hydrogeologic characteristics of the basin have been
defined, a representative rainfall period (i.e., baseline period) is selected, from which pumpage
and the change in groundwater in storage values can be derived. The selected baseline period
should not be preceded by a hydrologically high rainfall period to avoid so-called water-in-transit
problems. Following selection of a representative rainfall baseline period, and assuming
representative water well operations, the volume of pumped groundwater during that period is
totaled and an average annual pumpage volume is calculated for this baseline period. The net
change of groundwater in storage occurring between the beginning and the end of the selected
baseline period is then determined and an average annual change in groundwater in storage is
calculated. The annual sustainable yield is then the algebraic sum of the calculated values of
average annual pumpage and average annual change in groundwater in storage.
Generally, storativity (or storage coefficient) is the degree to which an unconfined or confined
aquifer system yields water to a well; i.e., it is the amount of groundwater in storage that can be
provided to a well and is governed by the equation: S = SSb + Sy
Where: S = the storativity
SS = the specific storage
b = the aquifer thickness.
Sy = the specific yield (that amount of water yielded only
by gravity drainage)
Because the pumping and change-in-storage method relies on the specific yield of an aquifer,
then for unconfined alluvial aquifers the specific yield is approximately equal to the storativity
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(the water that can be provided to a well by gravity drainage). However, for confined aquifers
the storativity can be greater, because water is supplied to a well not only by gravity drainage
but also by that delivered by an increase in the volume of the water pumped from storage, due
to lowering the amount of head (pressure) in an aquifer. Thus, as noted previously, the change-
in-storage method is considered to provide conservative results for a confined aquifer system,
which could yield lower values. Thus, actual changes in groundwater in storage are difficult to
quantify, but uncertainty in the calculated values can be reduced by further characterization of
the hydrogeologic conditions through the application of additional hydrogeological data such as
geophysical logs, pumping tests of local wells, and reasonable compensating factors, such as
future recharge volumes not previously considered.
Recognizing the likelihood of lack of available hydrogeologic data and the inherent uncertainties
in those data that are available, the pumpage and change-in-storage method is still applicable
for estimating the sustainable yield of the subject subbasins, because the City has sufficient
data on SWLs and groundwater extraction volumes from each of its wells, and estimates can be
made for the known private-party pumping in at least one of the subbasins of the SMGB.
Accordingly, the only items required to be analyzed when applying the pumping and change-in-
storage method to evaluate the sustainable yield of the local subbasins are the following.
o Precipitation over the study area, as obtained from a representative rain gage.
o Volume of groundwater in storage, as calculated from estimates of the specific yield
of the sediments and the total footage of saturated aquifer systems, as identified by
evaluation of available electric logs of the boreholes for water wells and wildcat
oil/gas wells.
o Representative annual groundwater withdrawals obtained directly from City records
and from estimates of pumpage by others.
o Recognition that both unconfined and confined aquifer conditions exist in the SMGB,
and therefore resulting estimates of sustainable yield are conservative.
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FINDINGS
GROUNDWATER BASIN AND SUBBASIN BOUNDARIES
Figure 1, “Location Map of Study Area”, in Appendix 1, shows the setting of the City of Santa
Monica, relative to the State of California. Figure 2, “Map of Groundwater Basins”, in Appendix
2, illustrates the boundaries of the City relative to those of the SMGB and other groundwater
basins that adjoin the SMGB. The SMGB, which is currently non-adjudicated, encompasses a
surface area of approximately 50 square miles (sq mi). The current surface boundary of the
SMGB (and those of the adjoining groundwater basins) is based primarily on published DWR
studies (1961, 1965 & 2016). The boundaries of this basin underlie the entire City limits and
extend beyond City boundaries into those of the City of Los Angeles on the north, east and
south.
Even though this report discusses and provides estimates of the sustainable yield of the five
locally-known subbasins identified previously by others within the SMGB, the following is to be
noted: the Santa Monica Basin, as defined by DWR Bulletin 118 Update (2016), is known as the
“Coastal Plain of Los Angeles – Santa Monica Basin (Basin No. 4-011-01). As such, two key
DWR components of the definition of this basin and its boundaries are:
1. No individual subbasins were recognized within the SMGB by DWR.
2. The entire eastern boundary of SMGB was taken by DWR to be along the general
northwest-southeast alignment of the Newport-Inglewood fault zone (in fact, DWR
has shown this fault to extend northward to the bedrock at the toe of the south flank
of the Santa Monica Mountains).
The MWD published a study in 2007 to describe the numerous groundwater basins within its
large service area. In that study, the MWD (2007) delineated five separate subbasins within the
SMGB, namely the Arcadia, Charnock, Coastal, Crestal, and Olympic subbasins. Figure 3A,
“Groundwater Subbasin Boundary Map,” in Appendix 1, illustrates the names and approximate
locations of the five groundwater subbasins identified in that MWD study within the SMGB. The
basis for the delineation of these groundwater subbasins and their respective boundaries are
unknown, as there does not appear to be any available reports that specifically identify when
and how those subbasins and their names/boundaries were first formulated. However, the
subbasin boundaries appear to loosely coincide with major geological structural features (e.g.,
faults) in the SMGB, but in some cases certain subbasin boundaries do not follow the reported
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ground surface traces of such features. For example, the southern boundary of the Olympic
subbasin does not exactly follow that of the Santa Monica fault zone, and the eastern border of
the Charnock subbasin appears not to follow the ground surface alignment of the Overland Ave
fault (see Figure 3A).
As of April 2018, there are 17 existing municipal-supply water wells owned by the City in the
SMGB. Of these wells, 10 are being pumped on an active basis to help meet the current water
demand of its residents and customers. The other seven City wells are either inactive or are
otherwise not in operation. Table1, “Summary of Well Construction Data for Historic and
Existing City Wells Used in this Study” in Appendix 2, provides the construction data available
for each existing City water-supply well. Figure 3B, “Map of City Well Locations,” shows: the
locations and names of existing City wells; the DWR-defined (2016) basin boundaries for the
SMGB; and other pertinent information.
GENERAL GEOLOGIC/HYDROGEOLOGIC CONDITIONS
RCS (2013) prepared a report for the City to provide its professional opinions regarding the
subsurface hydrogeologic conditions throughout the SMGB; thus, the reader is referred to that
report for a detailed discussion of those conditions. For the purposes of this study, only a
summary of the hydrogeologic conditions provided in that RCS 2013 report is presented herein,
because the focus of this study is to provide estimates of the sustainable yield of the subject
subbasins for which requisite data are available.
Figure 4A, “Generalized Geologic Map of the Santa Monica Area,” and its companion, Figure 4B
“Generalized Geologic Map Legend & Symbols,” illustrate the geologic conditions as mapped at
ground surface by others throughout the SMGB (as identified by DWR, 2016), and provide the
legend to the geologic symbols shown on Figure 4A, respectively. Figure 5, “General
Stratigraphic Section for the Coastal Plain of Los Angeles County,” shows the stratigraphic
relationships and basic geologic framework of the different geologic formations shown in Figure
4A, as mapped by the DWR (1961). Specifically, the sediments/rocks within and beneath the
SMGB portion of the City of Santa Monica are divided into two broad groups: 1) a potentially
water-bearing sediments group (these deposits tend to be readily capable of absorbing, storing,
transmitting and yielding groundwater to water wells); and 2) a non-water-bearing rocks group
which underlies the water-bearing sediments and which are comprised by geologically old,
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lithified, or cemented sedimentary rocks and/or crystalline rocks of low permeability. These two
groups of earth materials are described below.
Water-Bearing Sediments
Recent (Holocene) Alluvium
Alluvium, which is of the Recent or Holocene in geologic age, occurs along and
within the relatively narrow mountain front canyons and creek channels that drain
across the SMGB. These Recent alluvial deposits are geologically young and likely
attain a maximum thickness of only perhaps 50 to 150 ft in the Santa Monica area.
In general, these earth materials are relatively shallow deposits of unconsolidated to
poorly consolidated, complexly inter-layered and inter-fingered deposits comprised
by gravel, sand, silt and clay. Permeability ranges from moderate in the coarser-
grained sand units to relatively low in the clay-rich layers. Groundwater, where
present in this shallow aquifer system, is considered to occur under water table
conditions (unconfined), and, thus, this groundwater occurs strictly within the void
spaces between the gravel and sand grains in each layer. Because of their limited
areal (spatial) extent and their limited thickness, these alluvial deposits are not a
viable source of groundwater for the City.
Lakewood Formation
The Lakewood Formation, which is of upper Pleistocene age, lies directly beneath
the various alluvial deposits in the region. The upper portion of this formation is of
continental origin (i.e., its sediments were shed from the north and east by the
erosion of the Santa Monica Mountains and other, local but smaller highland areas).
In contrast, the lower portion of this formation reportedly contains sediments of
marine origin (sediments deposited by the ocean). Overall, this formation is
comprised by layers and lenses of poorly consolidated gravel, sand, silt and clay.
The DWR (1961) has identified and named several aquifers in the Lakewood
Formation in the Coastal Plain area of Los Angeles County. These aquifers include:
the “Palos Verdes Sand;” the Exposition aquifer; the Gage aquifer; and the Gardena
aquifer (see Figure 5). Each of these sandy and/or gravelly aquifers is separated by
fine-grained, silty and/or clayey strata known as aquicludes; such aquicludes have
only limited permeability and are not considered usable as potential sources of
groundwater. However, these aquifers have not been documented by the DWR or
others to be present in the SMGB. Thus, these strata were either never originally
deposited in the basin, or the original formation sediments were subsequently
removed by erosion following their deposition. Hence, groundwater from this
formation would not be available to the City for any future water wells.
San Pedro Formation
Directly underlying the Lakewood Formation is the San Pedro Formation of lower
Pleistocene age. According to DWR (1961 and 1965), this formation may attain a
maximum thickness of from 100 to 280 ft in the Santa Monica area, whereas it may
attain a thickness up to 300 ft in the Ballona Gap to the south.
Key aquifers identified and named by DWR (1961; see Figure 5) within this formation
include, from “top” to “bottom,” the following: the Hollydale aquifer, the Jefferson
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aquifer, the Lynwood aquifer, the Silverado aquifer, and the Sunnyside aquifer
(which is very near the base/bottom of the entire formation). Once again, these
aquifers are separated by various thicknesses of intervening fine-grained, clay-rich
aquicludes of much lower permeability. The Silverado aquifer is well known because
it is pumped by many water wells across the entire Coastal Plain of Los Angeles
County. In SMGB, many of the stratigraphically higher (shallower and younger)
aquifers have been removed by erosion after their deposition, and only the Silverado
aquifer is interpreted by the DWR (1961) to exist. It is possible, however, that the
Sunnyside aquifer may also be present and, if so, it would form the base of the
aquifer systems available to new wells in the local groundwater subbasins.
One notable consideration for some of the aquifers in the San Pedro Formation is
that they often contain uniform, fine-grained sands, which if not properly accounted
for during the design and construction of a new water well, tend to enter the
perforated sections of the well casing whenever the well is pumped; this leads to
sand in the groundwater pumped from a well (i.e., such a well is known as a “sander,
such as the former SM-7 which was recently replaced by the City with well SM-8.
Another notable consideration for these aquifers, and for the San Pedro Formation
as a whole, is that they have been impacted over time by geologic forces, mainly
faults, which have offset and displaced the earth materials and created possible
barriers to groundwater flow. In addition, folds are present which have “bent” or
“warped” the sedimentary layers into different inclinations from the horizontal.
Driller’s logs of water wells and available geophysical electric logs (E-Logs) of water
wells and wildcat oil wells have been acquired and reviewed by RCS. Those efforts
reveal that the San Pedro Formation is comprised by moderately consolidated and
stratified layers and lenses of fine-grained gravel, sand and silt which contain various
amounts of clay (RCS, 2013). Colors in these layers and lenses vary from tan to buff
to yellow brown in the upper portions of the formation; such colors indicate an
oxidizing environment. Older portions, nearer the base of the formation, tend to be
of marine origin, tend to have a gray to gray black color, and often contain fossil
marine shells. Those darker colors indicate an anaerobic, or reducing, environment.
As noted above, only the lower (and somewhat more consolidated) portion of the
San Pedro Formation exists in the SMGB. Further, correlation of available E-logs
reveals the overall thickness of this formation is essentially zero along the front of the
Santa Monica Mountains on the north side of SMGB, and thickens to perhaps 300 to
400 ft on the south side of the basin. Importantly, this formation supplies nearly all
the groundwater being pumped by existing (and future) water wells in SMGB.
Non-water-Bearing Rocks
Immediately beneath the San Pedro Formation (i.e., the bottom of which is generally considered
to form the base of fresh water in the SMGB) is the Pico Formation of upper Pliocene age.
Even though this formation may contain some groundwater, it is generally considered to be not
capable of yielding water to wells in sufficient quantities and of adequate quality for municipal-
supply purposes; hence it is also considered herein to be “non-water-bearing;” albeit a few wells
in the Lakewood area have been reported to obtain usable groundwater from the Pico
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Formation (DWR, 1961). Local examples are Arcadia Well Nos. 4 and 5, which appear to have
at least some of their perforations (in the lower portion of each well) placed into the upper
portion of the Pico Formation.
Strata within the Pico Formation tend to be well-bedded and well-consolidated, and to consist
principally of interbedded deposits of clay, silt, sand and gravel of marine origin. Individual beds
of gravels and sands are reported to range in thickness from 20 to 100 feet and are separated
by thicker beds of clay and micaceous siltstone (by DWR, 1961). The Pico Formation is also
known to contain petroleum and/or natural gas (often methane) at greater depths.
Below not only the base of the water-bearing sediments which form the SMGB, but also
beneath the Pico Formation, and as also exposed at ground surface in the Santa Monica
Mountains to the north, are a series of geologically older, lithified and/or cemented, sedimentary
rock formations and various crystalline metamorphic and igneous rocks. Because of their
lithified and/or cemented and/or crystalline character, these rocks do not contain free water in
the interstices between the individual sand or gravel grains or within the matrix of the rock.
Rather, the groundwater in these rocks is contained solely within fractures, joints, and/or along
bedding planes. Hence, the groundwater storage capacity of these rocks is low, and their long-
term ability to yield groundwater to water wells is poor. Consequently, only limited quantities of
water are available to wells from these types of rocks. Moreover, electric log signatures of the
sedimentary rocks in this group, as encountered in deep wildcat oil/gas wells in and around the
SMGB, suggest the contained groundwater is brackish in character and non-potable. It is likely
the original connate water in the existing sedimentary rocks was never flushed by percolating
fresh water over time. For these reasons, these rocks are classified as non-water-bearing in the
Santa Monica region and, therefore, these older formations and rocks are the local bedrock (or
basement rock), and they are also not a part of the SMGB.
Geologic Structures
There are several significant geologic structures, consisting chiefly of faults, that occur
throughout the Los Angeles Coastal Plain region and a few of these occur in and proximal to the
SMGB. These structures can impact the movement and direction of groundwater and have been
selected by others to form the boundaries between adjoining groundwater basins in the Coastal
Plain, and even between the subbasins (as defined by others) which comprise the SMGB (as
defined by DWR). A more detailed discussion of these local faults was provided in RCS (2013)
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and is presented herein strictly for information purposes, regarding the SMGB and its subbasin
boundaries. It is not within the scope of services for this project to describe or evaluate the
relative movement of these faults and/or their history of or potential for movement. Figure 6,
“Map of Watershed and Local Drainages,” shows, among other things, the approximate
locations of the faults described herein.
Key structures mapped by others to define the boundaries of the SMGB and its subbasins,
include the following:
o The Hollywood-Brentwood fault system, which traverses the area in a general east-
west direction across the northern edge and north-central portion of the SMGB. This
fault system forms the northern boundary of the Olympic subbasin (i.e., the southern
boundary of the Arcadia subbasin).
o The Santa Monica fault system, which extends across the basin in a general east-
west direction, forms the northern boundary of the Coastal subbasin (or the southern
boundary of the Olympic subbasin). Based on modeling conducted by the City, an
alternative interpretation is that this fault may not extend upward into the shallower
sediments nearer ground surface in the Olympic subbasin. This scenario could
provide a pathway for recharge from the Olympic subbasin into the Coastal
subbasin.
o The Newport-Inglewood fault zone, which traverses in a general southeast to
northwest direction across the Coastal Plain, is considered to form the eastern
boundary of SMGB and its Crestal subbasin. As seen on Figure 4A, DWR has
extended this fault northward to the southern edge of the Santa Monica Mountains.
Thus, this fault (per DWR) forms the boundary between the SMGB on the west and
the Hollywood Groundwater Basin and the Central Groundwater Basin on the east.
o The Overland Ave fault, which is an en-echelon fault associated with the Newport-
Inglewood fault zone, which creates the eastern boundary of the Charnock subbasin.
o The Charnock fault parallels both the Overland Ave fault and the Newport-Inglewood
fault zone and forms the eastern boundary of the Coastal subbasin (or western
boundary of the Charnock subbasin).
o The Santa Monica Mountains delineate the northern boundary of the SMGB whereas
the Ballona Escarpment demarks the southern boundary of the SMGB (see figures
3A & 4A).
o The westerly boundary of the SMGB is the Pacific Ocean.
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WATERSHED AREA
There are several canyons located along the front of the Santa Monica Mountains that drain in a
general southerly direction from those mountains into the SMGB. Figure 6 illustrates the
locations and names of the key local drainages and the main watershed divide along/near the
crest of the Santa Monica Mountains, north of the City. The watershed boundary has been
adapted from a watershed map prepared by the Interagency Watershed Mapping Committee
(October 1999). Also shown on Figure 6 are: the City limits; the boundaries for DWR’s SMGB;
and the names and boundaries for the subbasins within the SMGB, as identified by others. As
noted above, some of these faults have been taken by others to form the boundaries between
those individual subbasins.
Figure 6 illustrates only that watershed area where the local streams can drain directly into and
across the SMGB. Rainfall falling within this watershed will have the potential to directly
recharge the aquifer systems underlying the northern and central portions of this basin. Thus,
the aquifers underlying the SMGB are recharged in part by deep percolation of direct runoff in
streams crossing the Santa Monica area. Another component of recharge to the shallow aquifer
systems would also occur by percolation of direct precipitation on the topographically flatter
portions of the local subbasins (i.e., the areas located south of the Santa Monica Mountains).
One other recharge component is deep percolation of excess irrigation on: residential lawns;
golf course turf; park areas; and even landscaped street medians.
Based on Figure 6, the area of the watershed, including the mountain/hillside areas and the
SMGB itself, was calculated to be approximately 86 sq mi. Of this, approximately 36 sq mi are
comprised by the largely undeveloped hillsides on the south flank of the Santa Monica
Mountains, whereas the remaining 50 sq mi are occupied by the surface area of the SMGB
which extends south to the northern boundary of the West Coast Groundwater Basin (WCB; see
Figure 6).
There is likely an additional input of recharge to the SMGB from the Hollywood and Central
groundwater basins on the east, and perhaps also from the WCB on the south (minor amounts
of rainfall recharge from this basin occur, due to drainage from the Ballona Escarpment area).
Recharge to SMGB from these adjoining groundwater basins would occur via subsurface
underflow (see locations of these adjoining groundwater basins on Figure 3A and/or Figure 6A).
While the amounts of such underflow are unknown, the aforementioned USGS modeling report
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and the related ICF Technical Memorandum pertaining to mountain front recharge suggests
these volumes of underflow could be significant. Furthermore, a portion of surface water runoff
along Ballona Creek can recharge the sediments of the shallow Ballona aquifer, but most of the
surface runoff along this creek eventually drains to the Pacific Ocean. The magnitude of the
amount of recharge along Ballona Creek to the deeper aquifer systems, such as the Palos
Verdes sand, the Silverado aquifer, and/or the Sunnyside aquifer, is unknown.
The Newport-Inglewood fault zone along the east side of the SMGB is, at least, a partial barrier
to groundwater flow from the east to the west. Thus, additional inputs of recharge water to
deeper aquifer systems along this boundary, such as the Palos Verdes sand, and the Silverado
and the Sunnyside aquifers may not be significant. Further, because these aquifer systems
generally dip from north to the south across the SMGB, and this dip direction continues
southward into the WCB, any recharge along Ballona Creek (in the southern portion of SMGB)
would likely flow southward and, therefore, it would not add to the groundwater in storage
beneath the City.
NATURAL RECHARGE
The aquifer systems underlying the City are generally replenished by rainfall falling directly on
the surface of the land, through infiltration of stream runoff along canyons/streams and gullies,
especially along the front of the Santa Monica Mountains, and by irrigation return water.
Recharge along the front of the Santa Monica Mountains and into the sediments of the Sawtelle
Plain are likely significant along major canyons, such as Rustic, Santa Monica/Sullivan,
Mandeville, Kenter, Sepulveda, Dry and Stone canyons.
To better quantify recharge in the SMGB, the City retained ICF to determine potential recharge
based on a detailed study on the subject prepared jointly by the United States Geological
Survey (USGS) and the Water Replenishment District of Southern California (WRD) titled;
Estimating Spatially and Temporally Varying Recharge and Runoff from Precipitation and Urban
Irrigation in the Los Angeles Basin, Scientific Investigations Report 2016-5068. As part of this
detailed study, the USGS assessed the amount of water that can be attributed to natural
recharge from precipitation, runoff and urban irrigation (USGS, 2016) for the Los Angeles
(coastal) basin, which includes the SMGB. The USGS study also included all the surface water
drainages bordering the SMB (e.g., mountain-front areas) that could potentially contribute
recharge to the adjacent sediments in the basin. The USGS developed a model which
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incorporated a new method for estimating recharge from residential and commercial landscape
irrigation based on land use and the percentage of pervious land area. The USGS model also
assessed climate data from over 200 monitoring sites, including monthly precipitation and
maximum and minimum air temperatures. It also included data for land use type, land cover,
soil, vegetation and surficial geology. The model was calibrated to available stream flow
records.
Based on their review of the USGS data, ICF found that the potential combined average
mountain-front and urban inflow into the SMGB was on the order of 11,212 AFY, not including
recharge from the estimated volume of non-revenue City water which is currently thought to
range between 2% and 5% of the total treated water placed into distribution within the City’s
water system. Thus, for 2017, the volume of non-revenue water could be approximately 226 to
565 AFY. Recognizing that the valleys and ridges of the mountain-front represent a three-
dimensional terrain that contains additional surface area not accounted for in a traditional two-
dimensional area calculation, the City had a LiDAR base map prepared and then overlaid a
Triangular Irregular Network System (TINS) on the topography which allowed a computer
algorithm to calculate the surface area as if the mountain ridges were flattened out. An analysis
of the TINS data by Earth Consultants International (ECI) estimated an approximate 12%
increase of mountain-front recharge area. When this information is factored into the USGS
inflow average, the annual inflow could be on the order of 11,927 AFY, or a range of 12,153 to
12,492 AFY when the estimate of non-revenue water inflow (226 to 565 AFY; see above) is
added to the overall USGS inflow volume. A copy of the ICF Technical Memorandum is
provided in Appendix 3.
Preliminary DInSAR data compiled by ECI suggests that other inflow may be occurring in the
near subsurface from mountain-front areas outside of the SMGB. If confirmed by the ongoing
Supplemental DInSAR study, the estimated inflow from these distant recharge areas could
increase the total inflow into the SMGB by perhaps an additional 716 to 1,000 AFY, bringing the
range of the average potential SMGB inflow to be 12,869 to 13,492 AFY.
Outflow from the SMGB to the northern end of the West Coast Basin (WCB) appears to be
indicated in Figure 2.1 of the “Regional Groundwater Monitoring Report for Water Year 2015-
2016,” as published by WRD; that figure is reproduced herein as Figure 7, “Groundwater
Elevation Contours of the West Coast & Central Groundwater Basins.” Review of Figure 7,
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which shows contours of the equal elevation of groundwater for Fall 2017, reveals that due to
pumping within the WCB, the overall direction of groundwater flow at the northwestern portion of
that basin, and in the area between the Charnock fault and the Newport-Inglewood fault zone, is
generally towards the southeast. This can be seen by groundwater contours being between
mean sea level (msl) and 10 ft below msl in the area southwest of the Charnock fault and
between 20 to 70 ft below msl in that area between the Charnock fault and the Newport-
Inglewood fault zone (see Figure 7).
To assess these possible outflow conditions and how they relate to the Coastal subbasin and
the overall sustainable yield of the SMGB, the City is planning to work in close consultation with
the USGS on a phased project to, among other things, integrate the City’s existing groundwater
flow data that is wellfield-specific, into the broader USGS flow modeling for the SMGB. When
completed, the integrated flow model will provide the City with a powerful tool for the adaptive
management of its groundwater resources. Current plans are to have a preliminary version of
the integrated flow model by the USGS available by 2020.
ARTIFICIAL RECHARGE AND CONSERVATION
Introduction
Artificial recharge can be important to the overall water balance and is typically conducted by
either directly injecting properly-treated water into the subsurface via recharge (injection) wells,
or by allowing water to percolate into the subsurface sediments by diverting surface water into
artificially-constructed basins known as spreading grounds.
Because of the degree of urbanization within the City and the surrounding groundwater
subbasins, there is insufficient available land area to support artificial recharge on the scale
necessary to derive maximum benefit via the construction of spreading basins at ground surface
in the SMGB. Further, the surface sediments in many parts of the City are fine-grained, with a
high percentage of poorly permeable silt and clay, making surface water percolation in those
areas less feasible.
According to available records, the City conducted limited subsurface recharge of imported
MWD water at one of its wells in the Charnock wellfield for a period of approximately 13 years
(between 1975 and 1988). However, the amount of water injected was relatively small and
ranged only from 0.3 AF in 1977 to 2,533 AF in 1979 (see RCS, 2013). Specifically, the City’s
Charnock Well No. 12 was used to inject the imported MWD water to help replenish the aquifer
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systems in this Charnock wellfield area. However, that well was destroyed in the 1990s and
water is no longer being injected by the City into any well at its Charnock wellfield (or any other
City wellfield) at this time
As discussed earlier in this report, a key objective of the City’s SWIP is to produce highly treated
water that, when properly permitted, could provide as much as approximately 1,100 AFY of new
water for aquifer recharge at the Olympic wellfield. The SWIP is scheduled to begin construction
in 2019, and the City has already embarked on the permitting process for SWIP treated water
applications with the LARWQCB, State Water Board Division of Drinking Water (DDW), and the
LACDPH.
Sustainable Water Master Plan
Santa Monica is a recognized leader in California for its environmental and water conservation
policies. The City has been actively implementing water efficiency programs since 1988 and is
one of the original signatories to the State’s Memorandum of Understanding Regarding Urban
Water Conservation in California (MOU) adopted in 1991 and amended in 2008. In 2014, the
City adopted a Sustainable Water Master Plan (SWMP) with the goal of achieving water supply
self-sufficiency in 2020 by eliminating reliance on imported water from the Metropolitan Water
District (MWD). Since the adoption of the SWMP, the City has been actively implementing new
water supply, water reuse and conservation programs and projects to achieve this objective.
Two City conservation programs that influence both local water demand and irrigation, and
hence, the sustainable yield of the subbasins within the SMGB are:
Water Neutrality Ordinance
On July 1, 2017, the new Water Neutrality Ordinance went into effect capping water use
for new developments to the average five-year historical use for that individual parcel. If
the projected annual water use for the development is greater than the existing annual
average for that parcel over the past five years, the increased amount must be offset by
water-efficient retrofits of an existing building somewhere else in the City. Offset retrofits
currently include low-flow indoor fixtures (toilets, showerheads, and aerators). The
ordinance applies to pools, ponds, spas and other water features as well. This ordinance
was developed and is currently being implemented by the City (SMMC 7.16.050).
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Water Efficient Landscape and Irrigation Standards
Green Building Ordinance Update: Santa Monica has had a Green Building Ordinance
with irrigation components since 2008. In December 2016, the ordinance was
significantly updated to reduce the amount of outdoor water use for new developments.
Overhead spray irrigation is banned for all new developments and for new landscape on
existing developments. In addition, turf grass is banned on new commercial
developments and is limited to 20% of landscaped area for new residential
developments. (SMMC 8.108).
Taken together, these two programs, along with other permanent non-behavior-based
conservation programs (e.g., low flow toilets, washing machine replacement at multi-
family units etc.), are estimated to be able to conserve approximately 1.5 to 3.0% of the
total water demand of the City by 2020. Reduction in total future demand by either
conservation or reuse will result in savings in local groundwater production and helps
support the City’s twin long-term objectives of protecting and sustaining the strategic
yields of its groundwater resources and water self-reliance.
HYDROLOGIC BASELINE CONDITIONS
Rainfall Totals
As discussed in previous sections, direct rainfall both local and on adjacent mountain front
areas and its subsequent runoff and deep percolation has a very important impact on
groundwater levels and, hence, on the effect of recharge to groundwater in the local SMGB.
Further, ongoing conservation programs that provide for permanent water savings and aquifer
recharge via the SWIP will reduce demand and contribute towards offsetting natural potential
outflow from the SMGB. To help calculate the estimated sustainable yield, RCS utilized
information provided in the ICF Technical Memorandum and acquired available rainfall data
through the website of the Western Regional Climate Center (WRCC) for the Desert Research
Institute at the University of Nevada, Reno for several (four) rain gages within and around the
SMGB, to compare the data from each of the gages. The rain gages assessed in this study are:
o Gage WR047953 at the Santa Monica Pier (however, no data are available after
2016 for this gage).
o Gage WR044214 in the Center of Culver City
o Gage WR049152 at the University of California, Los Angeles (UCLA).
o Gage WR045114 at Los Angeles International Airport (LAX) which is located south of
and outside of the SMGB and, thus, is not directly applicable to conditions affecting
the Santa Monica area. It is used herein only for the purposes of comparison.
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These rain gages are generally located on the west, south of, in the southeast portion, and in
the northeast portion of the SMGB. The approximate locations of these rain gages, as provided
by the WRCC, are shown in Figure 6.
Figure 8A, “Annual Rainfall Totals”, in Appendix 1, illustrates the annual rainfall totals as a bar
graph for all four rain gages; these data span a maximum period of record from 1934 through
2017 (depending on the rain gage, because the beginning and ending years for each rain gage
are different, as shown thereon). Based on these rainfall data, the following are notable:
O The long-term average annual rainfall for the four rain gages from this period of record
(1937 through 2017) ranges from 10.91 inches (through 2016) at the Santa Monica Pier
rain gage, to 16.22 inches at the UCLA rain gage located near the northeastern corner
of the SMGB.
O The highest annual rainfall totals generally occurred at the UCLA rain gage, whereas
the lowest annual rainfall totals typically occurred at the Santa Monica Pier rain gage.
This phenomenon is likely attributable to the effects of orographic lifting which causes
moist air to cool and induce precipitation as it moves up and over the Santa Monica
Mountains, thus accounting for the higher totals at the UCLA gauge and along the
mountain front in general.
Accumulated Departure of Rainfall
Figure 8B, “Accumulated Departure of Rainfall” (Appendix 1), shows the local annual patterns in
rainfall for the period of record of the various rain gages and is used to ascertain if there is a
correlation between wet periods and wellfield water levels (i.e., recharge). The accumulated
rainfall departure values on the figure are plotted relative to the long-term average annual rainfall
for each of the rain gages and their respective period of record. The accumulated departure curve
illustrates temporal trends in the rainfall data and helps to identify local long-term patterns (or
trends) in rainfall over time. This figure reveals the following:
O Those portions of the curve ascending towards the right-hand side of the graph
(positive slopes) indicate a series of years when the annual rainfall was generally at or
above the long-term average. Thus, this defines a generally “wet” period, when the
accumulated precipitation totals were increasing, relative to the long-term mean value.
Conversely, the slopes of the curves declining to the right-hand side of the graph
(negative slopes) indicate those years where accumulated precipitation totals were
declining, relative to the long-term average; these declining trends represent general
periods of deficient rainfall or a “dry hydrologic period” (i.e., a drought). These “wet” and
“dry” periods are specifically denoted on Figure 8B for the rain gage data evaluated
herein.
O Based on the data, three rain gauges more or less correlate with each other. Those
gauges are Culver City, LAX, and UCLA. Data from the fourth gage, Santa Monica Pier,
appears skewed, and therefore was not considered further. Of the three remaining
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gages, the Culver City gage was selected for use in this study due to its proximity and
compliance with the selection criteria listed below.
Selection of Baseline Hydrologic Period
A key step in determination of the sustainable yield utilizing the pumpage and change in storage
method is the selection of hydrologic baseline period for rainfall that would be representative of
long-term conditions, as obtained from an accumulated departure curve. These data would then
be correlated to static (non-pumping) water levels at/near the City’s wellfields.
In selecting such a baseline period from the selected accumulated departure curve, the
following criteria were utilized:
o The period includes both hydrologically wet and dry cycles.
o The period ends near the present for which historical data are available.
o The accumulated departure from mean annual precipitation is similar for the
beginning and end of the period.
o Cultural conditions are similar at the start and end of the period.
o Adequate data on water levels and groundwater extractions are available throughout
the identified baseline period.
Review of Figure 8B shows that the rain gages at LAX and UCLA display very similar trends
over time, with respect to their accumulated departure percentages. The Culver City gage,
although it has similar trends as those for the LAX and UCLA gages from the early-1980s
onward, displayed different trends than those two gages prior to the early-1980s. Figure 9,
“Selected Baseline Period,” shows that the 30-year period from 1988 through 2017 satisfies the
above criteria, particularly for the Culver City and LAX rain gages, as follows:
o The 30-year period for these two rain gages includes both a hydrologically wet cycle
and a hydrologically dry cycle. The years 1992 through 2010 may be considered a
“wet” cycle, whereas the years 1988 through 1992 and 2010 through 2016 constitute
a “dry” cycle. However, there is a slight deviation from this in the Santa Monica Pier
and UCLA rain gages, which show that the ”wet” cycle at the outset of 1988 in the
previous two curves commences a year before.
o Sufficient historical data are available for pumping withdrawals and static water
levels for the new 30-year period (1988 through 2017).
o The accumulated departure from mean annual precipitation occurs at approximately
the same “level” in 1988 as it does in 2017 for the two key rain gages (Culver City
and LAX). However, and particularly for the Santa Monica Pier rain gage but also
somewhat for the UCLA rain gage, the accumulated departure differs considerably.
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The following compares the average historic rainfall to the average rainfall for the 1988 through
2017 for the LAX and Culver City gages:
Rain
Gage
Rainfall Average,
Period of Record
(inches)
Rainfall Average
1988 - 2017
(inches)
Culver City 12.02 11.88
LAX 11.77 11.60
o The differences in average rainfall for the 30-year baseline period between the
Culver City and LAX rain gages are 0.14 inches and 0.17 inches, respectively.
o Current cultural conditions in the SMGB (population, developed area, etc.) are similar
to what they were in 1990, although the population has increased slightly, from
approximately 86,900 in 1990 (US Bureau of the Census, 1992) to the current
93,000. This is an increase of around 6,100 over 27 years
o There is sufficient historical data available from the various City wells, for annual
rainfall conditions, and for groundwater withdrawals by the City over the 30-year
baseline period. However, reliable static water levels not available for all City
wellfields; this may be particularly true for the Charnock wellfield.
For this study, the accumulated departure of rainfall curve for Culver City was selected as a
“best fit.” Thus, these data were used to help discern possible trends in the SWLs in City water-
supply wells, as discussed later herein.
GROUNDWATER WITHDRAWALS
Withdrawals by the City
Available data for the total historic groundwater production from each City-owned wellfield have
been tabulated, along with RCS estimates of private pumpage by others, on Table 2,
“Groundwater Production from City Wells and Other Wells (1988 through September 2017).”
The tabulated values for historic total annual groundwater withdrawals during this 30-year
period were those available from: City reports and Excel spreadsheet data provided to RCS by
the City for its wells in the Arcadia, Charnock, and Olympic subbasins; from another third party
water company well owner, for its limited production from its Charnock wellfield up through
1996; and from RCS estimates of groundwater withdrawals for irrigation-supply from private
wells located at two known golf courses in Arcadia subbasin. There have never been any
active, City-owned, municipal-supply wells in the Coastal or Crestal subbasins and, thus, there
are no City withdrawal data for these two subbasins.
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Table 2 presents data for the period of 1988 through 2017 hydrologic baseline period and
shows the following:
a) The Arcadia wellfield has historically been the least productive of the three existing
City wellfields. Minimum and maximum annual groundwater production at this
wellfield has ranged from 0 AF for at least 4 years (1997 through 1999) to 714 AF in
2014. The average annual groundwater production by active wells at this wellfield
was approximately 440 AFY during the 30-year baseline period. By way of
comparison, groundwater extracted for the recent five year period between 2013 and
2017, the average was 635 AFY at that wellfield.
b) The Charnock wellfield continues be the most productive of the City’s three
wellfields. Minimum and maximum groundwater withdrawals have been: 0 AFY in
the 13-year period 1997-2009, inclusive, which was caused by problems relating to
third party groundwater contamination at and near this wellfield; and 8,377 AF in
2014. For the 30 years of data on Table 2, discounting the 13 years when the entire
wellfield was purposely shut down, the long-term average annual withdrawal was
approximately 6,290 AF. However, given the fact that various wells are known to
have had mechanical and/or regulatory limitations that have affected wellfield
production, it is likely that the estimated sustainable production rate for the wellfield
has been previously underestimated, especially when estimates of basinwide
recharge are considered. For the five year period between 2013 and 2107 the
average withdrawal was 8,048 AFY. In further recognition of this supposition, the City
is exploring the acquisition of an existing but currently unused water-supply well on
an adjacent property owned by a third party. That “new” well would likely increase
overall production by the City from the Charnock wellfield region by 1,450 to 1610
AFY.
c) The Olympic wellfield represents the second most productive of the three City’s
existing wellfields. As seen on Table 2, the minimum annual groundwater production
from this wellfield was 385 AF in 2004, whereas its largest annual production volume
was 3,176 AF in 1995. The average annual production from this wellfield during the
30-year baseline period was 1,860 AF. Like the Charnock wellfield, the Olympic
wellfield has also experienced periods of mechanical problems and regulatory
limitations related to is overall annual production rates and volumes, and thus when
the estimates of basin inflow are considered, the sustainable production capacity of
this wellfield is likely greater than the current annual average extraction value.
Examples of operational limitations include restricted production in 2003-2004 due to
nearby leaking underground fuel storage tanks, and well casing problems in SM-3
that required a new liner to be installed. This casing liner had the effect of
significantly reducing the amount of water that could be pumped from this well.
Recently the City has constructed a new well (SM-8) that is believed to be capable of
producing approximately 970 AFY of additional water. The City also plans to replace
the deficient SM-3 well. That new well, when completed later this year, is anticipated
to be capable of producing approximately 750 gpm, or ±1,200 AFY. Lastly, when
properly permitted, highly-treated water from the SWIP can be artificially recharged
into the aquifer systems near SM-8; the overall production from that well and
available groundwater yield from this wellfield should increase.
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The total groundwater withdrawals from the three subbasins in which the City has had its active
wells has ranged approximately from 522 AF in 2004, to 11,001 AF in 2016. The average
annual production during the 30-year baseline period has been on the order of 8,590 AFY for all
City-owned wells. This average production includes only those years in which pumping was
performed by the City from the three subbasins, which eliminates the 4 years of non-pumping
conditions in the Arcadia subbasin (from 1997 through 2000), and the 13 years of non-pumping
conditions from the Charnock subbasin (from 1997 through 2008). As noted above, it does not
consider documented mechanical or regulatory limitations that may have adversely affected
production rates; see Table 2.
It should be noted that a few City wells, namely Arcadia Nos. 4 and 5, Santa Monica No. 3, and
Charnock No. 13, reportedly had wire-wrapped steel liners installed inside the original well
casing at some time after the original construction of the well. Such casing liners are needed
when, for example, the original well begins to pump sand. The typical impact of these liners on
each well is to reduce the overall specific capacity of the wells, thereby increasing the amount of
drawdown in the well and/or limiting the ability of the wells to pump at its former rates.
However, it does not necessarily limit the ability of the wells to produce the same volume of
water prior to liner installation, because the same water volume can be pumped if the newly-
lined well pumps for a longer duration, but at its lower rate. As noted elsewhere herein, the City
has plans to replace SM-3 with a new well in the future.
Groundwater Withdrawals by Others
The only other existing groundwater withdrawals that currently occur in the SMGB subbasins
are from one privately-owned residential irrigation well, and irrigation wells at three golf courses,
namely the Brentwood Country Club (BCC), the Riviera Country Club (RCC), and the Los
Angeles Country Club (LACC). Because the three golf courses lie mainly within the City of Los
Angeles, it can be assumed that Los Angeles provides potable water for all domestic needs at
those golf courses. Thus, the onsite water wells at each golf course are assumed herein to
provide sufficient groundwater to meet the entire annual irrigation demands of each golf club
(i.e., none of the water supplied by the City of Los Angeles is assumed to be used for irrigation-
supply). Two other golf courses exist in the SMGB, the Bel Air Country Club and the Penmar
Country Club. However, neither of these courses reportedly has any existing onsite water-
supply wells at this time.
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Historically, there have been other wells that were known to have formerly been used to extract
groundwater for municipal-supply from the SMGB. These wells are owned by a third party and
were reported to include the following:
Wells at that third party’s Charnock wellfield in the Charnock subbasin; the last wells
in this wellfield were shut down at the end of 1996 due to the presence of MTBE
contamination in the groundwater being pumped by the City’s Charnock wells
located to the northeast. In the last two years of active use, those remaining third
party-owned Charnock wells pumped a total of approximately 570 AFY. This
average value has been listed in Table 2 for each of the years in which these wells
were reportedly pumping during the baseline period. One of these wells, Charnock
No. 10, reportedly had a pumping capacity of 900 to 1,000 gpm (1,450- 1,610 AFY).
A few wells at its Sepulveda Plant in the Charnock subbasin, which terminated
production in ±1960, and hence, this production precedes the onset of our 30-year
baseline period.
A few wells at its Manning Plant in the Crestal subbasin, but these wells were all
destroyed during the construction of the I-10 Freeway, which pre-dates the baseline
period being studied for this updated project.
Data are sparse, but reportedly only a limited number of wells existed at its former
Pacific Plant, Lincoln Plant, PenMar Plant, and Zanja Plant, all of which were in the
Coastal subbasin. These wells and wellfields no longer exist and, although the date
of the most recent production by any of these wells is unknown, it is highly likely that
none were active at any time during the baseline study period for this project.
Actual groundwater production data from the wells at the known golf courses are not available
to the City for this study. To assess the magnitude of the groundwater extractions at the golf
courses listed above, RCS used computer methods and Google Earth® imagery and estimated
that the total irrigated areas of turf on those “local” golf courses are on the order of 105 acres for
the BCC golf course, 125 acres for the RCC golf course, and 170 acres at LACC (note, there
are two, 18-hole courses at this latter country club). Further, in coastal areas of southern
California, it is reasonable to assume that each acre of golf course turf requires on the order of
2.5 AF of water for irrigation each year.
Furthermore, the amount of groundwater pumped on an annual basis by the known small
diameter irrigation well located at the residence along San Vicente Blvd. However, using the
above estimate for the golf courses, and estimating an irrigated acreage of slightly greater than
one acre on this residential lot, then it is estimated that a maximum of about 2 AF of water per
year would likely be pumped by that privately-owned residential well. This annual volume is
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considered by RCS to be insignificant for this update of the sustainable yield analysis and will
not be considered further herein.
Based on the assumptions above, and the above-approximated irrigated acreages and unit
irrigation demands for typical coastal-area golf courses in southern California, the assumed total
annual irrigation demands supplied by groundwater pumped by wells at those three golf courses
could be as follows: 260 AFY for BCC; 310 AFY for RCC; and 450 AFY for LACC (note that
these values assume that any/all golf course wells at those golf courses have been in active use
throughout the entire 30-year baseline period being used herein). Thus, private groundwater
withdrawals by others for irrigation-supply in the Arcadia subbasin would total ±570 AFY (for the
BCC and RCC), whereas those in the Crestal subbasin would be ±450 AFY (as noted above,
LACC has two, 18-hole golf courses on its property). It is not known whether UCLA and/or the
Veterans Administration facilities, which are also in the Crestal subbasin area, have any active
water-supply wells at this time.
WATER LEVELS
Water Level Hydrographs
Graphs of water levels versus time were used to help discern trends in SWLs over time in City
water-supply wells within SMGB. Thus, these hydrographs were used to determine in which
portions of the subbasins where the City has active wells, water levels are rising or declining
over time and which areas of those subbasins may be more influenced directly by rainfall
recharge. Figures 10A through 10C provide graphs of water levels versus time (i.e.,
hydrographs) for the wells with available data in each City wellfield (or subbasin) in which the
City has water wells. These hydrographs have been plotted along with the accumulated
departure of rainfall for the base period using the Culver City rain gage, to illustrate the possible
correlation between changes in water levels and changes in rainfall over time. Recharge as
underflow from the adjacent mountain front areas is not included in these estimates but was
accounted for in the estimates of sustainable yield, via changes in water levels. In addition, the
same horizontal and vertical scales have been used for each graph to show comparative
differences between the hydrographs, which had to be expanded due to the limited amplitude of
water level fluctuations in the wells in the subbasin over time. For this current study, historic
SWL data from the previous RCS (2013) report were updated with more recently obtained data,
updated through 2017 for City wells, as provided by City staff. It should be noted that there are
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likely some inherent discrepancies in the accuracy of the SWL data reported over the 30 year
baseline period, as the method of collecting data in the field can and often does vary over time.
Therefore, the use of hydrographs from these wellfields for estimating sustainable yield likely
result in estimates that are conservatively low. Review of the hydrographs reveals the following:
o Arcadia Wellfield/Subbasin. Water level data are available for five City wells in the
Arcadia subbasin. These wells include the three Arcadia wells (Nos. 2, 4, and 5;
Well No. 2 has been destroyed, and only Well Nos. 4 and 5 are active) and two
Santa Monica wells (Nos. 1 and 5). Updated SWLs were available only for Santa
Monica Well Nos. 1 and 5 (through December 2017) and Arcadia Well No. 4 (through
March 2017). Review of Figure 10A, “Arcadia Wellfield/Subbasin Hydrographs,”
shows that the three Arcadia wells all have similar water level depths and similar
water level trends over time. Most SWLs in these three wells over their respective
periods of record were typically at depths in the range of 10 ft to ±60 ft bgs; a few
water levels for these wells are anomalously deep and are likely pumping water
levels.
In comparison, for Santa Monica Well Nos. 1 and 5, even though their water levels
are similar, the water level depths in these two wells differ considerably from those in
the Arcadia wells. Specifically, during their respective periods of available data, SWL
depths in Santa Monica Well Nos. 1 and 5 were typically at depths in the range of 90
ft to ±140 ft bgs (not including the anomalously deep wells). Generally, Santa
Monica Well Nos. 1 and 5 are located west of the City’s Arcadia wellfield (see Figure
3) and have slightly different hydrogeologic conditions.
Relative to the accumulated departure of rainfall curve for the Culver City rain gage
on Figure 10A, a clear correspondence between patterns in SWLs and rainfall is
difficult to discern in the Arcadia wellfield wells. This may be due to the possibility
that pumping water levels (or even non-representative SWLs taken shortly following
shutdown of the pump in the wells) have been recorded as SWL data, and/or that it
is difficult to obtain accurate SWLs in any of these wells because wells in this
wellfield are closely spaced, thereby inducing water level drawdown interference on
one another when pumping. However, where there are relatively consistent SWL
data (such as in 1943 through 1950), then a trend can be seen to emerge: the SWLs
in the Arcadia wells appear to be acting in concert with the accumulated departure of
rainfall curve within that period. However, the water level data for Santa Monica Well
No. 5 reveal a much greater degree of agreement with the accumulated rainfall
departure curve on Figure 10A. That is, yearly changes in its SWLs appear to be
mimicking changing rainfall trends.
Also notable on the Figure 10A hydrograph for the Arcadia wells is that none of the
SWLs over time attain a depth that is shallower than about ±5 to 7 ft bgs, regardless
of the amount of antecedent rainfall. This suggests that these water levels represent
a “spill point” for Arcadia subbasin at/near this wellfield. That is, once water levels
rise to this depth, the groundwater may “spill” over the nearby fault and into the
adjacent Olympic subbasin to the south.
o Charnock Wellfield/Subbasin. Figure 10B, “Charnock Wellfield/Subbasin
Hydrographs,” illustrates the water level data for seven City wells in this wellfield (see
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Table 1 for construction data for the five currently-active wells in this wellfield); note,
over the years, at least 20 wells have been constructed for the City at this wellfield,
which lies west of Sawtelle Blvd in the City of Los Angeles (refer to Figure 3B for well
locations). Because the City’s Charnock wells tend to have similar depths and
similar perforated intervals, and are located very near one another, their water level
depths and trends over time are, as expected, seen to be similar on Figure 10B.
Notably, Well No. 7 has the longest period of available water level data of any well
shown on Figure 10B. Based on the operational use of this wellfield, and on a
review of the Charnock hydrographs on Figure 10B, the following are noted:
a. Many of the water level data prior to the mid-1990s may be considered as
being impacted by a wellfield pumping depression. That is, the various wells,
when actively pumping, would tend to create water level drawdown
interference on those wellfield wells that were not pumping at the time;
hence, a monitored water level in a non-pumping well would tend to be
lower than a true static level.
b. During the period of the wellfield shutdown from the mid-1990s through
±2010, water levels in all the wells showed a long-term and continuous period
of rise; this water level trend also matched a concomitant period of increased
rainfall (a “wet” period).
c. Once pumping in the wellfield resumed in ±2010, wellfield water levels
exhibited a rapid and relatively steep decline. This decline also was
consistent with the ongoing drought (as reduced recharge in direct local
precipitation) in southern California at this same time.
It is apparent on Figure 10B that the water level in the Charnock wellfield show some
response to changes in rainfall. For example, water levels for Well No. 7 between
1937 and 1955 appear to show general correspondence to rises and declines in the
accumulated departure of rainfall curve for the Culver City rain gage. However,
starting in 1955, and continuing until 1975, measured water levels appear to decline
whereas the accumulated departure of rainfall shows increasing rainfall conditions.
This anomaly may be explained by changes in wellfield operations that may have
affected pumping water levels (e.g., increased production rates, or recording
pumping water levels as SWLs). Between 1970 and 1995 the data are inconsistent
and lacking (possibly again due to vagaries in pumping rates and individual wells
potentially interfering with one another when pumping). However, in 1996 the water
level data for most of the wells become consistent, and all show a slow and
continuous rise over time. This phenomenon is basically a long-term record for the
recovery of all water levels in this entire wellfield, because these wells were all
inactive from ±1996 through ±2010, due to third party MTBE contamination
within/near the City’s Charnock wellfield. This unified response is likely the only true
record of static water levels for the wellfield and suggests that the other slight
deviations from matching the accumulated departure curve could be the result of
various wellfield operation activities and the monitoring of water levels that may not
have been true static water levels because they could have been impacted by
nearby pumping. Further supporting this hypothesis is the fact that since the pumps
in the seven active wells were turned back on in ±2011, water levels in those wells
have generally declined rapidly, and in unison.
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o Olympic Wellfield/Subbasin. Historically there have been three City wells in this
wellfield (Santa Monica Well Nos. 3, 4, and 7); each of these wells is located within a
median along Olympic Blvd (see Figure 3B). Two of these, Santa Monica Well Nos.
3 and 4, are currently active. In April 2018, construction of a new well for the City
was completed. This new well (SM-8) will serve as a replacement for well SM-7,
which was recently destroyed. New SM-8 has yet to be provided with a permanent
pump, but once permitted, it is expected to produce around 600 gpm.
Figure 10C, “Olympic Wellfield/Subbasin Hydrographs”, graphically depicts the
available water level data for the three historic wells over time. The data indicate
that the water levels from the three wells have had similar depths and trends over
time. SM-7, which has been out of production since 1989 except for a few brief
periods of pumping, was destroyed in 2018. Prior to that, it was used for static water
level monitoring. At least some of the water level data from SM-3 and SM-4 could be
considered water levels that have been impacted by nearby pumping. Water level
data from SM-7 has tended to exhibit slightly deeper water levels than those in the
other two wells. This could be because SM-7 is located down gradient from SM-3
and SM-4 and thus pumping at these two wells may be acting to dampen the water
level response measured in the former SM-7. In other words, inflow in to the
subbasin is possibly being diverted into the two producing wells before it reaches
SM-7. Comparing the SWLs to the accumulated departure of rainfall for the Culver
City rain gage for the period 1979 through 2017 for the wells shows that the data
generally correspond, but there is a noticeable amount of offset (i.e., a delay)
between changes in rainfall and a corresponding change in SWLs. For example, the
accumulated departure of rainfall curve indicates rising rainfall totals started in 1992
and continued until 1998. However, a rise in water level in these wells does not
commence until around 1996. Thus, there appears to be a three- to four-year lag
between changes in rainfall and changes in water levels However, this may be
attributed to the fact there was an increase in production levels at the Olympic
wellfield beginning around 1993 and continuing through much of this period.
Complicating this analysis is the down gradient location of SM-7 from SM-3 and SM-
4 and overall proximity of the wells to one another, two of which were producing
continuously for more or less the entire 30-year base line period.
o Coastal Subbasin. There are five existing wells in this subbasin; three of these are
inactive, and the remaining two are groundwater monitoring wells. Two of these
inactive wells, Saltwater Well Nos. 1 and 2, are located near Santa Monica Beach
near the west terminus of Pico Blvd. Saltwater Well Nos. 1 and 2 formerly produced
brine for a former treatment system at the City’s Arcadia Water Treatment facility, but
they are no longer used. The third well, Airport Well No. 1, was successfully
constructed as a municipal-supply well in April 2018, but it has yet to be equipped
with a permanent pump. This well is expected to produce around 300 gpm when it is
permitted for production. The City has plans to construct at least two other water-
supply wells in the future at the Santa Monica Airport.
The two groundwater monitoring wells include the Marine Park well, which is located
near the PGC at Marine Park, and the newly-constructed Colorado Yard No.1 well,
which was completed in November 2017. Except for the Airport Well No. 1 water-
supply well and the Colorado Yard monitoring well, the older wells are not
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representative of subbasin aquifer conditions, including usage for water level
monitoring because they are either too shallow, or in the case of the Salt Water
wells, they are too close to the beach, and therefore potentially subject to tidal
influences.
Water Level Hydrographs – “Key” Well Concept
In comparing the water level data in the wells to the baseline period and, ultimately, to estimate
the amount of change in storage in the subbasins for which data are available, RCS did not
need to use water level data for every City well, especially when such wells are located proximal
to each other in the three respective City wellfields. For example, there are several City wells at
the Charnock wellfield, all of which are perforated within the same aquifer systems and to
similar depths. As such, only one key well needed to be selected to be representative for this
individual wellfield. Measured water level data for this key well reflects water level changes that
are similar to those in other adjacent wells. To the extent possible, the selected key well also
had the longest and most complete period of record for the baseline period, in comparison to
the other wells in the same wellfield.
Figures 11A through 11C (in Appendix 1) provide graphs of the available water level data
versus time for “key” selected City wells in those groundwater subbasins of the SMGB, for which
data are available for City wells, for the 1988 through 2017 hydrologic baseline period. These
key wells were selected as being representative of changes in water levels over their period of
record and this selection was based on their geographic location, on the completeness of their
measured water level record, and on the length of their perforated intervals (that is, wells with
the longest length of perforation intervals would obtain their supply from multiple aquifer
systems).
Further, a schematic diagram of each selected “key” well is included on its respective figure
(Figures 11A through 11C) to illustrate the casing depth and the depths of the perforation
intervals in those wells (if the requisite casing data were available), in relation to the historical
water level data. The recorded water levels have been plotted based on their measured depth
from a base reference point (brp), which is assumed to be approximately at ground surface for
each well.
Arcadia Subbasin Key Well Hydrograph
Figure 11A, “Key Well Hydrograph, Santa Monica Well No. 5”, is a hydrograph of this
key City well to show SWLs vs time for the 30-year baseline period (located in the
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central portion of the Arcadia subbasin, in the northern portion of the City). Data from
this well, which was selected as being representative of changes in static water levels in
the Arcadia subbasin, have been plotted along with the accumulated departure of rainfall
for the Culver City rain gage (as adapted from Figure 9) for comparative purposes. Note
that the accumulative departure for each year represents the entire span for that year,
and not just the point on which the curve falls. Thus, for example, the accumulated
departure value for 2017 is based on the rainfall total through the end of that year.
Figure 11A reveals the following:
o The response of the measured water levels to increases in rainfall is illustrated
by the successive “up & down” patterns (i.e., rises and declines), noted by the
sawtooth pattern in water levels for Santa Monica Well No. 5. On an annual
basis, groundwater levels tend to be shallower in the early part of the year and
deeper near the end of each year. This graph illustrates that the response
between changes in rainfall is immediate and that changes in rainfall recharge
and changes in water levels have been relatively rapid; Figure 4 shows the well
is located near a stream, and the well has relatively shallow perforations (145 to
235 ft bgs). Thus, the nature of the water level responses could indicate that this
well contains at least part of its perforations within a shallow, unconfined (water
table) aquifer system that is responding to seasonal runoff in the stream bed that
is percolating into the subsurface. Also, of interest is that the water levels in this
well has never risen above a depth of ±108 ft bgs during its period of record,
regardless of the trend in the rainfall departure curve.
o In evaluating the total change in SW Ls (represented by the symbol ΔS on the
graph) during the baseline period, then the difference in the water levels between
the beginning and the end of the 30-year baseline period can be defined. This
difference amounts to approximately -8 ft on the graph; this represents an overall
decline in the measured water levels between the beginning and the end of the
baseline period. This calculation and its significance are discussed in greater
detail in the section below titled “Subunit/Subbasin Changes in Groundwater in
Storage Calculations”.
Charnock Subbasin Key Well Hydrograph
For this subbasin, there was only one well, namely Charnock Well No. 16, which had
adequate available historic data to permit an evaluation of the water levels for the
baseline period; the resulting data are shown in Figure 11B, “Key Well Hydrograph for
Charnock Well No. 16 & No. 20.” Note that nearly all the plotted water level data on the
figure are for Well No. 16, except for data from 2016- 2017, which includes data from the
adjacent well No. 20. Review of Figure 11B reveals the following:
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o Notable on this figure is the existence of the long-term and continuous rise in
water levels in this well that occurred between mid-1996 and late-2010. This is
the time during which the City’s entire Charnock wellfield was shut down due to
contamination of local groundwater by a third party and it is likely the only period
during which actual static water levels were recorded. This continuous rise in
water levels represents a long-term water level recovery period for this subbasin.
However, starting in late-2010, and after construction of the treatment plant for
this wellfield had been completed and pumping of the active wellfield had
resumed, water levels once again began to experience a steep and rapid decline
(to depths of 155 to 156 ft brp) by late-2016. This result is likely due to the
resumption of wellfield pumping involving numerous wells located very near one
another.
o The wellfield start-up happened to coincide with a marked decline in precipitation
for several subsequent years. This same relationship, a decline in precipitation
and measured water levels, for the period starting in late-2010 and continuing
until late-2016 is also seen on Figures 11A (Arcadia wellfield) and 11C (Olympic
wellfield).
Thus, it appears that water level responses in the various subbasins are
potentially affected by pumping wells that are sited very near one another, and
that the observed water level changes are prone to the vagaries of water level
recording methodology and how frequent actual SWL measurements versus
pumping water levels were and are being collected.
o The total change in water levels during the baseline period at this Charnock well,
represented by the symbol ΔS which is the difference in measured water levels
(combination of pumping and static) at the beginning and the end of that period,
amounts to +12 ft; this represents a water level rise between the beginning and
the end of the baseline period. This significance of this calculation, which
because of the admixture of water levels types may be conservative, is
discussed in greater detail in the section below titled “Subunit/Subbasin Changes
in Groundwater in Storage Calculations Olympic Subbasin Key Well
Hydrograph.”
Olympic Subbasin Key Well Hydrograph
There are only three City wells in this subbasin for which there are available water level
data. Those data for Santa Monica Well No. 7 are considered to be more representative
than the other two wells as an indicator of SWL changes in this subbasin for the baseline
period because the well was not pumped for an extended time, making the collection of
actual static water levels possible. However potentially countervailing this benefit, SM-7
was in proximity and down gradient from two active pumping wells in the subbasin (SM-3
and SM-4). The location of this well raises the possibility that water level records may be
conservatively low, as the upgradient production wells may have influenced local water
levels. Figure 11C, “Key Well Hydrograph for Santa Monica Well No. 7,” illustrates the
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water level changes. From roughly 1993 until ±2017, SWLs in SM-7 have generally
responded to longer-term trends in the accumulated rainfall departure curve for the
Culver City rain gage (see Figure 11C), even though shorter-term changes cannot be
discerned as readily. Additional review of the figure indicated the following:
o There are a few periods for which SWLs appear “depressed” (in the years 1988
to 1989 and late-1994 to early-1998), as shown by the symbol “P,” indicating that
these specific “SWLs” may have been measured during actual pumping of the
well, or that they were heavily influenced by recent pumping of the well (such as
a measurement taken shortly after pump shutdown). Thus, it is difficult to
determine an actual SWL that was not influenced by pumping. Nonetheless, if
we take the point in mid-1995 as representing a “representative” deep SWL, then
total water level change has amounted to 45 ft. In addition, the SWLs could have
also been influenced by pumping of nearby Santa Monica Well Nos. 3 and 4,
located east of Santa Monica Well No. 7. Note also on Figure 11C that SWL
depths in Well No. 7 have never declined to the depth to its uppermost
perforations during the baseline period.
o The SWLs in Well No. 7 also appear to show responses of the SWLs to longer-
term changes in rainfall, even though it is difficult to discern shorter term changes
like those for Santa Monica Well No. 5 in the Arcadia subbasin. This fact is
particularly noticeable after 2010, when both rainfall and SWLs show a declining
trend through to the end of the baseline period. However, correlation of SWLs to
trends in rainfall is not well-defined prior to that date. Further complicating this
analysis is the fact that mapping of the geology in the Olympic wellfield indicates
the possibility of faulting in the subsurface which, if confirmed, could act as a
barrier to block or delay some natural recharge from upgradient areas.
o The total change in water levels in this well during the baseline period (symbol
ΔS), is noted to be -30 ft, representing a decline in water levels between the
beginning and the end of the baseline period. The significance of this calculation
is discussed in greater detail in the section below titled “Subunit/Subbasin
Changes in Groundwater in Storage Calculations”. It should be noted that the
operational limitations discussed in this section, such as pumping wells being
located in proximity to each other may have resulted in increasing the amount of
water level change over time, which in turn would result in a conservative
estimate of sustainable yield.
Coastal Subbasin Key Well Hydrographs
There are no active City water-supply (production) wells within the Coastal subbasin,
although the City does own two local water level observation wells near the beach: Salt
Water Well Nos. 1 and 2. However, these two wells are not useful because the tidal
changes from the nearby ocean appear to be the principal cause of changes in SWLs in
these wells, and because they are too shallow to provide useful information for
estimating sustainable yield of this subbasin.
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Notably, the City has recently constructed two new production wells in this subbasin.
One such new well, City Hall Well No. 1, can produce at rates ranging from 8-10 gpm
and was constructed to be used solely meet the limited water demands at the new City
Services Building in the future. Specifically, this new well is for use by a special City
sustainable building project, which reportedly will require only approximately 10,000
gallons/day. City Hall Well No. 1 is very shallow and was cased to a depth of only 160 ft
bgs, with perforations being placed continuously between 60 and 160 ft bgs (see Table
1). Because this well is new, there are clearly no long-term SWL data for this well.
Hence, SWL data from this well have very limited use regarding determination of ΔS for
this subbasin. However, useful hydrogeologic data were obtained during the drilling,
construction, and testing of this new City well. That is, the borehole for this well was
drilled to a depth of approximately 652 ft bgs, and the new electric logs indicate that in
addition to the two water-bearing zones that were perforated in this shallow well, there
was another deeper, potentially water-bearing zone at a depth of approximately 280 ft to
300 ft bgs. The base of fresh water in this area was identified on the new electric logs to
be at a depth of approximately 540 ft bgs.
The second new production well in this subbasin, Airport Well No. 1, was drilled and
constructed to a depth of 610 ft bgs in April 2018; this well has perforations set between
the depths of 190 and 590 ft bgs (see Table 1). When tested, this well produced water
at a sustained pumping rate of 300 gpm. The City is also planning to construct two
additional wells in the Airport area, and it is anticipated that each of these two wells
could also be able to produce water at a rate of ±300 gpm. The results of the pumping
from new Airport Well No. 1 will be extrapolated to the two proposed wells and the
combined flows from the three wells will be used later in this report to provide an initial
estimate of the sustainable yield of this groundwater subbasin.
Crestal Subbasin Key Well Hydrograph
Currently, there are no readily available data on water levels for water-supply wells or
groundwater monitoring wells within this subbasin. Thus, trends and/or changes in SWLs
cannot be determined at this time; and, hence, there is no calculation herein for the ΔS
in this subbasin.
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GROUNDWATER IN STORAGE
Storage Subunits and Parameters
The locations and alignments of several faults in the SMGB, as mentioned in various geologic
publications and in the RCS (February 2013) report, were originally used by others (such as
MWD, 2007) to subdivide this groundwater basin into the five distinct subbasins.The faults may
or may not comprise barriers to groundwater flow. If these faults do define complete barriers,
groundwater could be discretely contained and/or compartmentalized within each subbasin. As
such, each of the five subbasins could conceivably comprise its own groundwater subunit. .
Recent studies conducted by the City by ICF (2018) and Earth Consultants International (ECI,
2017) to assess natural recharge into the SMGB have found that recharge from mountain-front
areas adjacent to the SMGB are a significant source of subsurface inflow. Further, a preliminary
DInSAR study conducted by ECI suggests that inflow from mountain-front areas outside of the
SMGB may also be occurring under certain conditions. These hypotheses are being tested in a
supplemental DInSAR study that is currently underway. Together, these studies have begun to
provide a basic understanding of how the individual subbasins are being recharged, how they
may be interacting, and what might be better approaches for sustainable and adaptive
management of these important groundwater resources.
Boundaries of the City of Santa Monica overlie portions of the Arcadia, Olympic and Coastal
subbasins; City limits do not overlie any portion of the Charnock or Crestal subbasins (indeed,
the City’s Charnock and Arcadia wellfields lie outside the City boundaries and within those of
the City of Los Angeles). However, because the City does derive a part of its supply from its
Charnock wellfield, the groundwater in storage has also been defined for this subbasin. The
Crestal subbasin was not evaluated at this time because the City has never, and does not
currently, obtain any of its groundwater supply from this subbasin.
To assess the volume (amount) of groundwater in storage in the subbasins, the following data
are needed:
o Groundwater Storage Subunits: The surface area of each of these subunits should
be defined where hydrogeologic/hydrologic boundaries do or are considered to
occur. Such boundaries may consist of: boundary faults (especially if these faults are
barriers to groundwater flow); streams or creeks that occur along the edges of the
basin and that may form a divide; and where bedrock/basement rocks meet alluvial
sediments. In addition, where applicable, it is conservatively assumed (to help
preclude seawater intrusion) that the western boundary of these subbasins generally
occurs in a buffer zone between the coast and Lincoln Blvd. Data from the City Hall
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No.1 well where the base of fresh water was encountered below a depth of 500 ft
indicates that salt water intrusion has not occurred in this buffer zone
Thus, the groundwater storage subunits defined for this study were considered to
represent the specific regions (i.e., the usable areas) where groundwater could
potentially be available to current and future City water-supply wells. In this current
report, the locations and names of the usable groundwater storage subunits are
shown in Figure 12, “Usable Areas of Groundwater Storage Subunits.”
o Saturated Thickness: This is a time-dependent value and is based on the depth to
SWLs (for a specific period) and on the actual depth to the base of fresh water
and/or the depth of the base of the water-bearing aquifer systems in the local
subbasin. The thickness of the water-bearing sediments herein is generally based
upon geologic cross sections which show the approximate base of fresh water, as
noted in the RCS report (2013). Calculations of the saturated thickness were based
on water level conditions during the baseline period. Thus, the calculation of the
volume of groundwater in storage is valid for any one point in time, because the
amount of groundwater in storage changes with either rising or declining water
levels; i.e., groundwater in storage must be recognized as a time-dependent variable
in a groundwater subbasin/basin.
o Specific Yield: This quantity is generally defined as the percentage of groundwater
in the void spaces (i.e., in the pore space) within the potentially water-bearing
sediments that will drain by gravity toward a well. Specific yield is primarily
dependent upon the characteristic type of the earth materials in a subbasin. For
example, clay or clayey sands tend to have a much lower specific yield (ranging from
2 to 7%) compared to that for gravelly sands (often 20% to 25%).
Calculation of Groundwater in Storage
The calculation of the theoretical volume of groundwater in storage (Sgw) was performed by
RCS (February and March 2013) using the following formula:
Sgw = (A) (b) (Sy), where:
A = The surface area of each subunit considered, in units of square miles (sq
mi), which is equal to the approximate width of the surface area times the
approximate length of the surface area. In the case of this current study,
each subunit was considered as being that region of the subbasin from
which groundwater could be available to existing or future City wells. The
units of surface area had to be converted from square miles to acres for
the final calculation. The surface areas used for each of the subbasins
are shown on Figure 12.
b = The saturated thickness of potentially water-bearing sediments, in units of
feet. The fault boundaries (by others) between the various
subbasins/subunits have been assumed herein to be vertical planes. In
this study, because RCS is not calculating the total amount of
groundwater in storage, but only the change in storage in each subbasin
(with requisite data) over the baseline period, then this quantity is
replaced by the change in water levels, or ΔS value.
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Sy = The assigned specific yield of the sediments, which was based on our
interpretation of the predominant type of sediments as listed on available
drillers’ logs for wells constructed in each subbasin.
The above factors determined the amount of groundwater in storage in each subbasin, in units
of cubic feet (ft3) of water, and these ft3 values were then converted into acre feet (AF).
SUBUNIT/SUBBASIN CHANGES IN GROUNDWATER IN STORAGE CALCULATIONS
The following provides the basic calculations for the changes in the amount of groundwater in
storage, over the baseline period, in each subbasin for which requisite data are available.
Subbasin boundaries have been adjusted slightly since the RCS (2013) report, regarding
calculating the area of usable groundwater in storage. That is, generally, Lincoln Blvd was
conservatively selected by RCS to be the westernmost boundary for the available groundwater
in storage in the region, whereas the southern boundary was selected to be along Washington
Blvd. Figure 12 shows the approximate boundaries of the “usable” groundwater storage
subunits delineated for this current study.
The method of determining the amount of change in groundwater in storage used in this
evaluation was calculated based on the changes in water levels during the entire 30-year
baseline period. However, pumping of the wells in the Arcadia and Charnock Subbasins was
not continuous, because the wells were shut down for various extended time periods. In the
case of the Arcadia subbasin, pumping at the Arcadia wellfield was shut down for four years
whereas for the Charnock subbasin, pumping at the City’s Charnock wellfield was shut down for
approximately 13 years. In the Olympic wellfield, pumping from City wells was conducted
during the entire 30-year baseline period. There are no current pumping data for the Coastal
subbasin, as the City is in the process of permitting its new Airport No. 1 well.
Change in Groundwater Storage
Arcadia Groundwater Storage Subunit/Subbasin
Only a small portion of the City overlies the Arcadia subbasin and five City wells
currently extract groundwater from this subbasin. Of these five wells, Santa Monica Well
No. 5 was used for the key hydrograph for this subbasin, primarily because this well was
not pumped during the hydrologic baseline period and, thus, its data provide a relatively
reliable picture of SWL changes in the subbasin. The following discusses the
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methodology for calculating the amount of change of groundwater in storage for this
groundwater subunit/subbasin:
o Area of Subunit: The entire area calculated for this subunit was based on that
region of the subbasin that was available to the City for withdrawal of
groundwater. The western border of this area is taken along Lincoln Blvd,
whereas its northern border is along the front of the Santa Monica Mountains; the
usable area of this subunit was measured to be approximately 6.6 sq mi.
o Change in W ater Levels (ΔS): For this subbasin, the change in the water levels
was determined by review of the water level hydrograph for the key City well in
the subbasin, namely Santa Monica Well No. 5, for the hydrologic baseline
period. This well was representative of the change in SWLs over time in this
entire subbasin. The change in groundwater is storage is the difference between
the SWL at the beginning of the hydrologic baseline period (in 1988) and the end
of the baseline period (end of 2017).
The hydrograph for this well (Figure 11A) indicates that ΔS, the change in water
levels over the baseline period for Santa Monica Well No. 5 was on the order of -
8 ft (i.e., SWLs declined by 8 ft over the baseline period). It should be noted that
this change is a negative quantity, because SWLs were shallower at the
beginning of the period (in 1988), than at the end of 2017.
o Specific Yield: As discussed in the RCS (2013) report, the sediments that are
perforated in the existing wells in the Arcadia Subbasin were variously described
on the available drillers’ logs as ranging from interbedded clay and gravel to fine-
grained silty sands and gravel to hard sandstone and rock. Based on our re-
review of those driller’s logs, Sy values for this subunit were assigned to be on
the order of 8% to 12%.
o Table 3, “Preliminary Calculations of Change in Groundwater in Storage During
the Baseline Period for the Arcadia, Charnock and Olympic Groundwater
Subbasins,” lists the resulting RCS calculations the changes in storage during
the baseline period, based on the assumptions and parameter values listed
above for the usable area in each subbasin for which adequate data are
available and in which the City has or could have its water-supply wells. It should
be noted that no values for the change in storage in the Coastal or Crestal
Subbasins have been provided because of the lack of data at this time.
Charnock Groundwater Storage Subunit/Subbasin
The Charnock subbasin occurs east of and outside of the City’s boundaries; currently
active City wells include Charnock Well Nos. 13, 15, 16, 18, 19 and 20. Of these six
wells, Well No. 16 was chosen as the key well hydrograph to represent changing water
levels over time, because it had data throughout most of the baseline period (see Figure
11B); recent data points for Well No. 20 were added to that graph, because Well No. 16
did not have any new data after early-2016 (pumping in that well has been continuous),
whereas Well No. 20 did have SWL data after that date. Because the two wells are near
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each other within the same wellfield, then the SWLs for Well No. 20 can be considered
representative and, thus, useful for inclusion into the Well No. 16 graph.
o Area of Subunit: This groundwater storage subunit, as measured for this
current study, has a usable surface area of approximately 3.7 sq mi, based
on a southern boundary along Washington Blvd.
o Change in Water Levels (ΔS): Figure 11B, the key well hydrograph for
Charnock Well No. 16 and No. 20, shows that at the beginning of the
baseline period the SWL was 158 ft bgs, whereas at the end of the baseline
period, the SWL was higher at 146 ft bgs. This represents a total change in
water levels of ±12 ft, or an increase over the baseline period.
o Specific Yield: As mentioned in the RCS (2013) report, the lithology of this
subbasin generally consists of interbedded brown clay to sand and gravel
and blue clay, sand to hard sand, and fine-grained sand to gravel. Additional
review of the driller’s logs for this study suggests that a reasonable range of
Sy values is 12% to 18% for this subbasin.
Table 3 shows that the change (in this case an increase as denoted by a positive set of
numbers in Table 3) in the groundwater in storage for the 1988 through 2017 hydrologic
baseline period for the Charnock Subbasin is on the order of 3,400 to 5,100 AF. For the
30-year baseline period, the average annual increase has been on the order of 120 to
180 AFY.
Olympic Groundwater Storage Subunit/Subbasin
The Olympic subbasin transects the central portion of the City, from the coastline on the
west to the Charnock fault on the east. Currently, only two wells, Santa Monica Well
Nos. 3 and 4, are used by the City to extract groundwater from the defined groundwater
storage subunit within this subbasin; Santa Monica Well No. 7 is used as a water level
observation well. For the purposes of this study, the hydrograph for Santa Monica Well
No. 7 was selected as the key well to represent changes in water levels over time,
because it has a relatively complete and continuous record of water levels. The
following summarizes the requisite parameters for this groundwater storage subunit:
o Area of Subunit: The area of this subunit was conservatively estimated, for
this current study, to be approximately 3 sq mi; the western boundary was
selected at Lincoln Blvd to help preclude seawater intrusion.
o Change in W ater Levels (ΔS): The Figure 11C hydrograph for Santa Monica
Well No. 7 reveals a SWL of 118 ft bgs, in early-1988. However, by the end
of the baseline period, the SWL was 148 ft bgs by late-2017. Thus, ΔS
amounts to approximately -30 ft in that well for the hydrologic baseline period.
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The negative number reveals a decline in the change in water levels across
this subbasin during the baseline period.
o Specific Yield: Based on additional review of the driller’s logs for wells in this
subbasin, average Sy values were considered to range from 10% to 15%.
Table 3 shows that the change (decline) in the groundwater in storage for the 1988
through 2017 hydrologic baseline period for the Olympic subbasin shows 5,900 to 8,800
AF. For the 30-year baseline period, the average annual decline has been on the order
of 200 to 300 AFY.
Coastal Groundwater Storage Subunit/Subbasin
Based on the results of the drilling and construction of municipal-supply Airport Well No.
1 and a new groundwater monitoring well at the City’s Colorado Yard, it appears that the
Coastal subbasin can support production wells. Based on pumping tests of Airport Well
No. 1, pumping rates are likely to be on the order of ±300 gpm. The City has plans for
two additional water-supply wells within the Santa Monica Airport in this subbasin.
Sustainable yield estimates for the Coastal subbasin are very preliminary because of the
lack of long-term SWL data. Future pumping from this subbasin will provide the data
needed to refine the potential range of sustainable yield for this subbasin. At this time
the results of pumping tests conducted at the end of the construction of the Airport Well
No. 1 have been used and extrapolated to the two additionally-planned City wells; the
combined value for the three wells could be used as a conservative baseline value for
the sustainable yield of this subbasin, until long-term SWL data become available and
can be evaluated.
The City has a new, successfully-constructed well, Airport Well No. 1 that pumped at a
sustained rate of 300 gpm during its recent constant rate pumping test. Below are
preliminary estimates of the various hydrogeologic parameters for this subbasin.
Regardless, long-term water level and pumpage data will still need to be obtained to
calculate the changes in storage in this subbasin over time. As this will require
additional years of pumpage and water level monitoring, and should a future well ever be
constructed at any of the three exploratory borehole sites, then other methods will likely
be needed to provide an estimate of the sustainable yield of this subbasin. The current
hydrogeologic parameters of the Coastal subbasin are as follows:
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o Area of Subunit: The area measured for the usable portion of the Coastal
subbasin, from Lincoln Blvd on the west and along the edge of the wetlands for
Ballona Creek, was determined to be approximately 7.1 sq mi. It should also be
noted that the recent well drilled and constructed at City Hall within this subbasin
demonstrated that the usable area for fresh water occurrence could possibly be
extended south of Lincoln Boulevard to an east-west line perhaps marked by 4th
Street. If this modification were to be included, it would add approximately 700
acres (about 1.1 square miles) to the overall usable area of the subbasin (for a
total of 8.2 sq mi).
o Saturated Thickness: A maximum thickness of the potentially water-bearing
sediments is estimated to be approximately 460 ft in this subbasin.
o Change in Storage: Due to a lack of available water level data, a ΔS value
cannot be determined at this time for the Coastal subbasin.
o Specific Yield: A range of average Sy values of 12 to 16% has been preliminarily
assigned to the earth materials in this subbasin, based on our review of drill
cuttings and geophysical logs from the recent drilling of Airport Well No. 1.
Currently, a change in groundwater storage cannot be calculated for the Coastal
subbasin, as there are no long-term SWL or associated groundwater extraction data.
When several years of groundwater extraction data become available and can be
reconciled with changes in SWLs, then the changes in groundwater in storage over a
specific baseline period may be preliminarily estimated for this Coastal subbasin. An
analysis of this remains for a future update of this current report.
PRELIMINARY CALCULATIONS OF SUSTAINABLE (PERENNIAL) YIELDS
As previously mentioned, sustainable yield is essentially analogous to perennial yield, and it is a
dynamic value, which can change under varying conditions of annual pumping and trends in
natural recharge over time. Thus, if sufficient groundwater withdrawal data and SWL data are
available, then the sustainable yield for each subbasin with requisite data can be determined in
the following manner:
(1) Selecting a baseline hydrologic period.
(2) Determining the average annual volume of groundwater extracted by the City (and
any known, privately-owned wells) during the baseline period.
(3) Computing the difference between the volume of groundwater in storage at the
beginning and at the end of the baseline period.
(4) Determining the average annual change of groundwater in storage from (3) above.
(5) Computing the algebraic sum of the average annual change of groundwater in
storage and the average volume of annual groundwater withdrawals by known water
wells.
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Table 4, “Updated Preliminary Calculations of Sustainable Yield, Three Santa Monica
Subbasins,” provides the calculated values for sustainable yield, based on the available data for
the entire 30-year baseline period. These data show that sustainable yield values determined
based on the entire baseline period range from as low as 870 AFY for the Arcadia subbasin, to
as high as 6,470 AFY for the Charnock subbasin (note that these values have been rounded to
the nearest 10 AF).
A preliminary sustainable yield value for the Coastal subbasin can be roughly estimated, based
on the results of pumping of the recently-constructed Airport Well No. 1 (April 2018). During its
final pumping tests, this well was pumped at a rate of 300 gpm. If the well were to continue to
produce at that rate on a year-round basis (i.e., a 100% operational pumping basis), the total
production from that one well would amount to 483 AFY. Extrapolating this to two additional
City wells that are in the planning stages for the Coastal subbasin, then the total that might be
produced from all three wells could be on the order of 1,450 AFY. Currently, if the assumption
is made that the Coastal subbasin were to be able to sustainably support the pumping of these
three new wells, without adversely impacting local SWLs over time, then this value could
potentially be used as the preliminary sustainable yield of this subbasin at this time. However, it
is cautioned that due to the complete lack of supporting data (such as long-term changes in
SWLs and, thus, a calculated value for the change in groundwater storage over a specific time
period), then any future calculated sustainable yield value for the Coastal subbasin could be
either higher or lower than this newly-estimated value. A possible range for the preliminary
sustainable yield for the Coastal subbasin currently is 1,160 to 1,450 AFY.
DISCUSSION OF HISTORICAL VALUES BY OTHERS
Comparison of Sustainable Yield Values
Table 5, “Comparison of Calculated Sustainable Yield Values, Santa Monica Subbasins,”
tabulates and compares the updated results of this study to the results of previous studies
conducted by RCS (2013) and others. The table shows the comparison of the sustainable
yields as follows:
o Arcadia subbasin: 870 to 920 AFY vs a previously-estimated value of 2,000 AFY by
others.
o Charnock subbasin: 6,410 to 6,470 AFY vs the previously-determined values of
4,420 to 8,200 AFY by others.
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o Olympic subbasin: 1,560 to 1,660 AFY, vs the previous value of 3,275 AFY
estimated by others.
o Coastal subbasin: 1,160 to 1,450 AFY, vs the previous value of 4,225 AFY by others.
As noted above, sustainable yield values for the Crestal subbasin could not be determined in
this current study because of the lack of available data. A previous estimate by others for the
Crestal subbasin was 2,000 AFY.
Arcadia Subbasin
In 1992, Kennedy Jenks Consultants (KJC, June 1992) prepared a groundwater management
plan for the City for its Charnock and Coastal subbasins. In that study, KJC derived a
sustainable yield value for a region that currently encompasses most/all the Arcadia, Coastal
and Olympic subbasins. In that groundwater management plan, KJC performed a statistical
evaluation of sustainable yield values. This was essentially the first type of “modeling” study
conducted for the SMGB and for the Charnock and Coastal subbasins. However, it should be
noted here that the “Charnock basin,” as defined by KJC, also consisted of the present Arcadia
and Olympic subbasins, whereas their Coastal subbasin boundaries are like the current ones.
In its model, changes in water levels were compared to groundwater withdrawal volumes by
KJC to determine the sustainable yield of the SMGB and its subbasins. KJC’s stated
assumptions were that under constant withdrawal rates, if water levels remain at a relatively
constant depth, then the pumping can be assumed to be within the sustainable yield limits of the
subbasin. Conversely, if water levels continued to decline under constant withdrawal rates, then
the sustainable yield of that subbasin was being exceeded.
KJC’s statistical evaluation involved plotting water levels versus groundwater withdrawal rates
and fitting a least-squares line (i.e., linear regression curve) through the plotted points. There
were a few types of statistical methods used:
o Water level elevations vs groundwater withdrawal volumes (in AFY).
o Annual withdrawals (in AF) and water level elevations vs date (years).
o Average annual water level elevations and pumping rates (in AF) vs date (years).
In addition, KJC also performed a groundwater basin budget evaluation, which consisted of
examining subsurface groundwater inflows and outflows, amounts of water imported into the
SMGB, groundwater recharges and discharges, determining groundwater flow directions and
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gradients (using the USGS MODFLOW computer modeling program), and groundwater in
storage.
Using the above analyses/estimation techniques for KJC’s combined Charnock and Coastal
subbasins, KJC determined the following:
o A sustainable yield value of between 5,500 and 7,000 AFY for the Charnock
subbasin (now the present Arcadia, Olympic and Charnock subbasins) via their
statistical analysis of the data. Using their groundwater basin budget estimation, a
range of 1,190 to 9,940 AFY, and a “probable yield” of 4,420 AFY were suggested by
KJC.
o No sustainable yield for the Coastal subbasin was calculated by KJC because of a
lack of data, and because the then-named “Potrero Canyon fault” (i.e., Brentwood
fault on Figure 3B) and the Santa Monica fault were considered to create a disruption
in groundwater flow patterns.
In late-1991 (contemporaneous with and based on the ongoing KJC study at that time), the City,
in an internal memorandum (August 23, 1991), assigned a value of 9,500 AFY for an entire area
termed therein as the “Santa Monica subbasin” (i.e., the combined Arcadia and Olympic
subbasins). Thus, the previous preliminary value of 2,000 AFY estimated by RCS (March 27,
2013) was based on a split of the difference between the 1991/1992 value for the “Santa
Monica subbasin” and the 1992 KJC value for only the Coastal subbasin. However, based on
this current study by RCS, a value of 870 to 920 AFY has been calculated to be the current
sustainable yield of the Arcadia subbasin.
Charnock Subbasin
The City (August 23, 1991) assigned a value of 6,000 AFY for the Charnock subbasin, based on
the results of the KJC study at that time. RCS review of the KJC (June 1992) report indicates
KJC provided a range of 6,000 to 6,500 AFY for this subbasin (June 1992, pg. 7-11). Thus, the
City appears to have assigned the lower value for sustainable yield for the KJC-noted range.
However, Komex H2O Science, Inc, (Komex, August 2001) provided a more recent estimate for
the “safe yield” of the Charnock subbasin using the following two methods:
o A “Direct Correlation” approach, which estimated changes in groundwater elevations
with changes in groundwater production. In this method, observed changes in
average groundwater elevations were plotted against average annual production
amounts. A linear regression curve was then applied to the plot. Points that fall on
this line were considered to correspond to a no net inflow or a no net outflow,
whereas points below the curve indicated average net inflow was lower than the
average production; points above the curve indicated that average net inflow was
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higher than the production. Using this method, Komex arrived at a value of 9,244
AFY for net inflow of the Charnock subbasin.
o In addition, a three-dimensional numerical model of the Charnock subbasin was
prepared, using software based on the USGS MODFLOW program. Their model
was also based on withdrawal data for the 1931 through 1950 periods. The average
annual production during that period was listed at 9,077 AFY, with a peak production
of 12,500 AFY in 1941. Based on their numerical model, Komex calculated a
sustainable yield value of 8,200 AFY for the Charnock subbasin using this approach,
as seen on Table 5.
It is important to note that Komex also conducted “overdraft” modeling scenarios to determine
the amount of groundwater that could be extracted from this subbasin. Key points of the Komex
modeling of the Charnock subbasin included:
o A “baseline” production capacity for the subbasin of approximately 8,200 AFY could
be maintained whereby water levels in the Silverado aquifer could be lowered to an
elevation of 120 ft below mean sea level (msl). This represents a water level depth
of approximately 217 ft bgs, based on an average ground surface elevation of 97 ft
above msl for the Charnock wellfield. The RCS-calculated water level decline was
98 ft during our baseline period, whereas the Komex decline was 142 ft; thus, this
partially accounts for the difference in the two sustainable yield calculations.
o Komex noted that water levels could be drawn down to an elevation of 200 ft below
msl (or 297 ft below msl), which is roughly the equivalent to 50% of the thickness of
the Silverado aquifer in this subbasin. After this, there would be a rapid water level
decline and depletion of the groundwater resource. Komex considered this to be the
“critical water level elevation.”
o Komex cited that the Charnock subbasin had a large storage capacity, using an
assigned specific yield value of 12% and a surface area of 4,200 acres for this
subbasin. Based on this, they also concluded that “…short-term fluctuations in
recharge that occur over a few to several years are damped out and do not appear to
affect the overall production capabilities or the average safe yield of the Sub-Basin.”
Based on their simulations, Komex provided a “best estimate” of the average “safe yield” of
8,200 AFY, with an “overdraft” protection of 10,500 AFY for the Charnock subbasin. This latter
“overdraft” protection value could be maintained for at least five years“…without lowering water
levels in the subbasin “beyond reasonable levels.” However, the actual depth (or elevation) of a
“reasonable” water level was not identified in their report. It should be noted that their modeling
was based on prior groundwater withdrawal values and SWL depths for the 1931 through 1950-
time period (Komex, 2001, p. 3). Notably, such “early” SWL data for the region are rare, and the
Komex study period is much earlier that that being used by RCS for this updated report.
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In March 2013, RCS, using a pumpage approach, estimated a preliminary sustainable yield of
the Charnock subbasin to conform to the Komex 2001 estimate of 8,200 AFY. Based on this
approach, the range of the estimated sustainable yields for the Charnock subbasin (derived by
RCS) is 6,410 AFY to an upper value of 8,080 AFY; this latter value is based on the earlier
Komex-derived value (refer to Table 6, “Potential Sustainable Yield Values, Santa Monica
Subbasins”).
As previously noted herein, the privately-owned third party well is known to have historically
constructed 10 wells at its own Charnock wellfield. None of these are currently in operation,
and only two of those wells still exist; the remaining eight third party wells have reportedly been
destroyed. Groundwater withdrawals from this third party-owned wellfield have been included in
our calculation of the updated sustainable yield of this subbasin, but only through 1996,
because production from their last two active wells was terminated at the end of 1996 due to
known MTBE contamination at the City’s Charnock wellfield, which lies to the northeast. Thus,
the period of groundwater withdrawals by this private company from the Charnock subbasin
unfortunately includes only the first few years of the 30-year baseline study period used herein.
The City is interested in acquiring the former third party Well No.10 and rehabilitating it for use
as a municipal-supply well for the City. Historically, this well was reportedly able to produce
between 800 to 1,000 gpm.
Olympic Subbasin
A previously estimated value by RCS (March 27, 2013) of 3,275 AFY had been assigned to this
subbasin. This estimate was based in part on the City’s Internal Memorandum (April 1991) and
KJC’s value (June 1992) for the Charnock subbasin. As shown on Table 6, the current
(updated) value by RCS of 2,360 to 3,145 AFY was estimated based on observed changes in
measured groundwater levels, recent data obtained during the drilling and construction of the
new SM-8, average groundwater extraction values over the hydrologic baseline period, and
aquifer recharge plans proposed by the City.
Coastal Subbasin
In its 2013 Memorandum, RCS assigned at a value of 4,225 AFY for the Coastal subbasin,
which was largely based on prior KJC studies. Recently-generated pumping test data from a
new City well in this subbasin (Airport Well No. 1), an updated, preliminary sustainable yield
value ranging from 1,160 AFY to 1,450 AFY is estimated, and these values are based on a total
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of three City wells, each pumping at a rate of 300 gpm, and at operational bases of 80% to
100% in the future. However, there are only limited available data on changes in SWLs from
prior production wells or groundwater monitoring wells within the Coastal subbasin. Thus, a
more refined estimate for the current sustainable yield of this subbasin is not possible until such
data for long-term changes in SWLs can be documented and reconciled with groundwater
extraction records. Pending such data, the current estimated sustainable yields may change to
a higher or lower value, based on the future impact of pumping of the wells on local SWLs over
time.
Crestal Subbasin
The previous sustainable yield value of 2,000 AFY was chiefly defined in a City of Los Angeles
Department of Water and Power (LADWP) report dated April 1991 which assigned a range of
values of 1,000 and 3,000 AFY for the sustainable yield of this subbasin. In RCS, (March 27,
2013), the midpoint of that range (i.e. 2,000 AFY) was selected as the preliminary sustainable
yield value for this subbasin. This current (updated) study herein has not been able to arrive at
a range of values, because of the lack of available data. Until additional data are obtained for
the Crestal Subbasin, the previous value of 2,000 AFY may be valid. As noted elsewhere
herein, it is probable that LACC may extract ±450 AFY of groundwater by its own private onsite,
irrigation-supply water wells in this subbasin.
FUTURE PLANNED WITHDRAWALS AND INJECTION
City staff plans to increase the production of groundwater from the Charnock and Olympic
subbasins, through the construction of additional water-supply wells, and also plans to increase
the volume of groundwater in storage using at least one new injection well. In the Charnock
subbasin, the plan is to add (utilize) an additional well, through the City’s acquisition of third
party-owned Charnock Wellfield Well No. 10, located 900 ft southwest of the City’s Charnock
wellfield. The City plans to pump this well at a rate of approximately 900 gpm in the future.
In the Olympic subbasin, the City plans to replace existing Santa Monica Well No. 3 and pump
the new replacement well (SM-9) at a rate of 600 gpm. In addition, if pumping of the newly-
constructed SM-8 is added to this (at a continuous rate of 600 gpm), then the total pumpage
from these two wells would be 1,200 gpm. Furthermore, the City is also planning to construct
an aquifer recharge well designed to inject up to 1,120 AFY of highly treated water from the
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City’s SWIP project. When completed, this well will help sustain the long-term yield of this
subbasin.
EVALUATION OF RAINFALL RECHARGE TO THE SANTA MONICA BASIN
ICF (May 2018) utilized a 2016 USGS report to estimate the amount of underflow and other
recharge entering the SMGB from various sources, including adjacent mountain front areas.
The ICF-estimated average potential recharge to the SMGB ranged from 12,131 to 12,722 AFY.
A significant portion of this volume was underflow in the subsurface from higher elevations
(mountain fronts) and from excess irrigation on residential properties. Assuming a conservative
estimate of 8% of this recharge would be able to deep percolate into the SMGB, where it would
tend to increase subbasin water levels, the range of sustainable yield for the SMGB could be on
the order of 11,800 to 14,725 AFY. Table 7, “Potential Lower and Upper Sustainable Yield
Values, Santa Monica Subbasins,” shows the sustainable yield values for each of the
subbasins, including the ICF recharge factors. The City is conducting a supplemental DiNSAR
study to further assess this recharge potential from ICF.
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CONCLUSIONS & RECOMMENDATIONS
Average subbasin withdrawals by known pumpers (i.e., the City, local golf courses and other
third parties) over the 30-year baseline period analyzed for this updated report, based on
average annual withdrawals over that baseline period are:
o Arcadia subbasin: 1,010 AFY
o Charnock subbasin: 6,290 AFY
o Olympic subbasin: 1,860 AFY
A separate calculation for the Coastal subbasin was performed and is based on future planned
withdrawals from new City wells to be constructed within the subbasin. These planned
withdrawals are preliminarily estimated to be 1,450 AFY. However, the effect of these planned
withdrawals on the change in storage in this subbasin will need to be evaluated later.
Based on available water level and groundwater withdrawal data, the results of this current
study show that the sustainable yields of the portions of the three subbasins of the SMGB that
are currently subject to City pumping and for which requisite data are available, are as follows:
870 to 920 AFY for the Arcadia subbasin; 6,410 to 8,080 AFY for the Charnock subbasin; 2,360
to 3,145 AFY for the Olympic subbasin; and 1,160 to 1,450 AFY for the Coastal subbasin
(preliminarily based on recent pumping tests of a new well in this subbasin). The total
sustainable yield from the four subbasins were calculated to be 10,800 to 13,595 AFY. If a
portion of the recharge to the SMGB estimated by others (ICF, 2018) is utilized, then the
sustainable yield could conceivably be as great as 11,800 to 14,725 for the SMGB. The Crestal
subbasin has not been included in this estimate because of the lack of available data to quantify
the sustainable yield in this subbasin.
Even though it has been shown (above) that up to 13,595 to 14,725 AFY could conceivably be
an upper limit for the sustainable yield, the potential impact on water levels and water quality are
temporal and require monitoring. Thus, the City must be diligent in obtaining reliable data on
SWLs, total annual groundwater extractions, and groundwater quality in the four subbasins and
in determining changes in storage, in order to preclude lower water levels that could ultimately
result, for example, in the intrusion of seawater into the SMGB.
It should be noted here that increased production from the City’s Charnock wellfield was made
possible by the recovery of water levels into the area during the non-pumping period from 1996
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through 2010. While there may be additional groundwater in storage throughout the SMGB,
such as that identified in the USGS and ICF reports that would allow for some greater amount of
groundwater withdrawals from the various subbasins, it may only be for short periods of time.
Such pumping, if conducted over too long of a period, could also lead to other conditions, such
as: a need to lower pump depth settings in existing wells; upwelling of poorer quality
groundwater from deeper earth materials; and the creation of cascading water conditions when
the wells are being pumped. The City must continue to be diligent about is ongoing program to
monitor and record SWLs (and total pumped groundwater withdrawals) for each of its wells in
the Arcadia, Charnock, Coastal and Olympic subbasins to update and refine the estimates of
sustainable yield.
Through the establishment of a network of both production wells and groundwater monitoring
wells and the ongoing, regular recording, monitoring and evaluation of resultant and reliable
data regarding SWLs and water quality [especially total dissolved solids (TDS) and chloride (Cl)
concentrations], then any changes indicating sea water intrusion can be determined, and the
pumping of the wells can be adjusted to reverse possible increases in TDS and Cl
concentrations. As such, the sustainable yields calculated in this current study will be further
refined over time.
RCS, as stated previously, recommends an operational pumping basis for active wells of ±80%
(i.e., actively using a well for 18 to 19 hours each day), instead of a 100% operational basis
wherein a well is never shut down. Such 100% continuous pumping (or injection) will tend to
create downwell problems and will not allow for routine operation and maintenance procedures.
Future groundwater withdrawals from the three active subbasins, within the limitations
presented by the estimated sustainable yields reported herein, indicate that the City’s approach
of investigating the water supply potential of the Coastal subbasin, and the pursuit of indirect
potable reuse from its planned Sustainable Water Infrastructure Project (SWIP), are both
prudent and necessary for the City to help achieve its long-term objective of independence from
imported water. It is recommended that the City continue its heretofore successful water
conservation programs, and to expedite the assessment of the Coastal subbasin. Identification
of viable groundwater reserves in the Coastal subbasin will help alleviate the current heavy
reliance on the three other subbasins which currently provide groundwater supply to the City.
These Coastal subbasin groundwater reserves could also facilitate the implementation of
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adaptive pumping measures, where individual wells or wellfields could be periodically rested to
allow for natural recharge.
Another key component to drought resiliency and water sustainability is the treatment and reuse
of non-conventional resources such as dry weather and storm-water runoff, brackish/saline
groundwater and municipal wastewater. The City is in the process of completing construction of
its Clean Beaches Project which will install a below grade 1.6 million-gallon storm-water harvest
tank north of the Santa Monica Pier. This innovative project will capture runoff from the Pier
Drainage Area for treatment at the City’s Santa Monica Urban Runoff Recycling Facility
(SMURRF). When runoff is scarce it will harvest brackish ground water from a gallery of
horizontal sub drains built beneath the tank. It is estimated that when complete this project will
help generate approximately 560 AFY of new water for immediate non-potable reuse and, when
properly permitted, it could likely be used for indirect potable reuse via aquifer recharge.
The SWIP is comprised of three integrated elements that once constructed will produce
approximately 1,100 AFY of new water from dry and wet weather runoff and municipal
wastewater. Water generated by the SWIP will be utilized primarily for aquifer recharge. The
SWIP is currently scheduled for completion in 2020. The City should expand the distributed
water strategy (i.e. stand alone, small scale) demonstrated by the Clean Beaches Project,
SMURRF and the SWIP to increase conjunctive reuse of all water resources, and especially
non-conventional resources, available to the City. As additional water resources are identified,
and the necessary infrastructure constructed, the use of imported water will continue to be
reduced.
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REFERENCES REVIEWED
Bredehoeft, J.D., Papadopulos, S.S., and Cooper, H.H., 1982, Groundwater: The Water Budget
Myth, in Scientific Basis of Water-Resources Management, Studies in Geophysics,
Washington D.C. National Academy Press. Pp. 51-57.
California Department of Water Resources (DWR), February 2017. Sustainable Groundwater
Management Web Site at: http://www.water.ca.gov/groundwater/sgm/definitions.cfm
_____, December 22,2016, California’s Groundwater, Working Toward Sustainability. Bulletin
118 Interim Update 2016. 44 pp.
_____, April 15, 2015, California’s Groundwater, Update 2013, A Compilation of Enhanced
Content for California Water Plan. Arranged in Multiple Sections.
_____, October 2003; California’s Groundwater. Bulletin No. 118-Update to 1975 version.
_____, February 2004; California’s Groundwater, Coastal Plain of Los Angeles Groundwater
Basin, Santa Monica Basin. Bulletin No. 118 Online Update.
_____, March 9, 2015, Sustainable Groundwater Management Program Draft Strategic Plan. 31
pp.
_____, June 1961, Planned Utilization of the Ground Water Basins of the Coastal Plain of Los
Angeles County - Appendix A, Ground Water Geology. Bulletin No. 104. 181 pp.
_____, October 1965, Water Well Standards, Central Hollywood, Santa Monica Basins, Los
Angeles County, Bulletin No. 74-4. 62 pp.
_____, September 1975, California’s Ground Water. Bulletin No. 118. 135 pp.
City of Santa Monica, August 23, 1991, Untitled Single Page Internal File Memo.
Farvolden, R.N., 1967, Methods of Study of the Ground-Water Budget in North America.
General Assembly of Bern. pp 108-125.
ICF Corporation, May 25, 2018, Final Draft: Evaluation of Recharge and its Effect on
Sustainable Yield in the Santa Monica Basin. 12 pp.
Earth Consultants International, 2017, Map generated using LIDAR topography.
Interagency Watershed Mapping Committee, October 1999, California Watersheds. Version 22.
Los Angeles Department of Water and Power, April 1991, Development of the Santa Monica
and Hollywood Groundwater Basins as a Water Supply Source for the City of Los
Angeles. 26 pp.
Kennedy/Jenks Consultants, June 1992; Santa Monica Groundwater Management Plan,
Charnock and Coastal Sub-Basins, Final Report; for the City of Santa Monica
Komex H2O Science, Inc, August 10, 2001, Estimates of Safe Yield for the Charnock Sub-
Basin. 6 pp.
Meinzer, O.E., 1923, Outline of Groundwater Hydrology, U.S. Geological Survey Professional
Paper 494. 71 pp,
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Metropolitan Water District of Southern California, September 2007, Groundwater Assessment
Study. Report No. 1308, Chapter IV. Pgs. 5-1 to 5-12.
Report of Referee, July 1962, The City of Los Angeles, plaintiff, vs. The City of San Fernando et
al, defendants. Superior Court of the State of California in and for the County of Los
Angeles Case No. 650079. Referee; State Water Rights Board. Two Volumes.
Richard C. Slade & Associates LLC, March 27, 2013, Review and Evaluation of Historic
Perennial Yield Values, Santa Monica Groundwater Basin, Los Angeles County. 8 pp.
_____, February 2013, Conceptual Groundwater Basin Model and Assessment of Available
Groundwater Supplies, Santa Monica Groundwater Basin. 119 pp. 14 plates.
_____, December 1986, Hydrogeologic Investigation, Perennial Yield and Artificial Recharge
Potential of the Alluvial Sediments in the Santa Clarita River Valley of Los Angeles County,
California. Report prepared for Upper Santa Clara Water Committee. 120 pp. 14 Plates.
Todd, D.K. 1059. Ground Water Hydrology. 535 pp.
USGS, 1999, Sustainability of Ground-Water Resources. Circular 1186 79 pp.
USGS, 2016, Estimating Spatially and Temporally Varying Recharge and Runoff from
Precipitation and Urban Irrigation in the Los Angeles Basin, California. Scientific
Investigations Report 2016-5068. 192 pp.
US Bureau of the Census, 2010, Summary Population and Housing Characteristics 2010.
Census of Population and Housing. Chps. 1-6.
US Bureau of the Census 1992, 1990 Census of Population General Population Characteristics
California Section 1 of 3. U.S. Department of Commerce, Economics and Statistics
Administration.
Water Replenishment District of Southern California (WRD), March 2017, Regional
Groundwater Monitoring Report, Water Year 2016-2017, Central and West Coast Basins, Los
Angeles County, California.
RCS
APPENDIX 1
FIGURES
Sequoia
National
Forest
"i fi r
?'jf
I
an
E
John Muir
Wilder nes,.
An;i --
N- nal
rest
des
Death Val
lt'Jdern-
LEI.
1411.1..
7.
Sp4
Santa Monicaonic ,'N
Riverside
Santa Ana
Guif nt ,So ,to ;no
0
MIN
2
Scale (in miles)
National Forest
San Bernardino
Cleveland
National
Forest
ONICA MIS
REC AREA
Joshua Tree
National
Park
Colorai
Riva Inds.
lastimat,i
5
Chmeokito Mountain
Naval Aerial
Gunnery Range
El Centro
Yuma
Proving
Ground
N. aria
45 90
Scale (in miles)
RCS RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
FIGURE 1
LOCATION MAP OF
STUDY AREA
RCS Job No. 462-LASOC June 2018
90 450
Scale (in miles)
20
Scale (in miles)
F IG U R E 1
L OC AT I O N M A P O F
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R CS Job No. 462-LA S O C June 2018
RIC HARD C. SLA DE & ASS OCIATES LLC
CONSULT ING GROUN DWATER GEOLOGI ST S
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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RC S Job No. 462-L ASOC June 2018
8 40
Scale (in miles)Adapted from DW R (1965)
City Boundary
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Sherman Oaks, CA 91401
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RC S Job No. 462-L A SOC June 2018
4 20
Scale (in miles)Adapted directly from M WD (2007)
City Boundary
RI CHAR D C. SL ADE & AS SOCIATES L LC
CON SULTING GROUNDWATER GEO LOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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SANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICA
MOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINS
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Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1
Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2
Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2
Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5
Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4
Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20Charnock Nos. 15 & 20
Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18
Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16
Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13
Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19
Colorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial ParkColorado Yard/Memorial Park Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4
Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7
Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3
Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1
Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6
City Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall Well
Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1
Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5
Richard C. Slade & Associates LLC
14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401
Phone: (818) 506-0418 Fax: (818) 506-1343
Figure 3B
Well Location Map
Consulting Groundwater Geologists
Date:
June 2018
Project No:
462-LASOC
Author: LAB/JA
Projection: Custom Projection
Filename:
Figure 4 Watershed
Map
Legend
Historic and/or Existing City Well Used in this Study
Key Well with Hydrograph Data in this Study
Name and approximate Boundary of Groundwater Basin
(as defined by DWR Bulletin 118 Update 2003)
Subbasin Boundary
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RCS RICHARD C. SLADE & ASSOCIATES LLC FIGURE 4A CONSULTING GROUNDWATER GEOLOGISTS
14051 Burbank Blvd., Suite 300 GENERALIZED GEOLOGIC MAP
Sherman Oaks, CA 91401
Southern California (818) 506-0418
m Northern California (707) 963-3914
www.rcslade.com
OF THE SANTA MONICA AREA
RCS Job No. 462-LASOC June 2018
F IG U R E 4A
G E N E R A L IZ E D GEO LO GI C MA P
O F T H E S A N TA MO N I CA AR EA
RC S Job No. 462-L A SOC June 2018
4 20
Scale (in miles)Adapted from DWR (1961)
City Boundary
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RICH ARD C. SLADE & ASSOC IATES LLC
C ONSU LTI NG GROUNDWATER GE OLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
SEDIMENTARY ROCKS
a
RECENT
PLEISTOCEN
PLIOCENE
MIOCENE
Sal ALLUVIUM
SIRIAVEL NA No TILT. ENO CLAY
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LAfEW000 FORMATION (INCLUDES -TERRACE DEPOSITS;
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LIAISE ANA CONTINE NEAL NAVEL is O, SENOE SILT. TILT,
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AND CLAT
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7.2..1 .:4vAT.AoLy CONSOLIDATED ORAvIL, SAND,
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PEPE T TO FORMATION
MARINE MILESTONE WITT LAYERS Or saRETTONE •NE
CINIELOSIERATE
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MODELO FORMATION
CONDLEMIENATic SAND5sONE, ULKIsFONE. AND TEALS
TOPANOA FORMATION
MARINE CONCIECIIIIRATE SANDSTONE. AND SHALE
PALOS VERDES HILLS I
MONTEREY FORMATION
VIM TOME, DIATOMITE, ENO SMILE
IELYSIAN HILLS, REPETTO HILLS, AND PUENTE HILLSI
PUENTE FORMAT ION
SENILE SILTSTANS, SANDSTDME, STALE, CONOLD AAAAAA
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OLIGOCENEITI VAQUEROS AND TAUPE FORMATIONS
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SHALE
PALEOCENEIT; L 1 UNDIVIDED MARTINEZ AND CHICO FORMATIONS
wl UPPER
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uPEER NAIHNE HESSEN-NAND CORPLONENATs, Ammo ',DNS,
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IGNEOUS ANO METAMORPHIC ROCKS
if MIDDLE MIOCENE VOLCANIC ROCKS
MIOCENEi VOLCANIC FLOW ONE COILS, TOFFS, ENO .T11, SITES CRIEILT
EASALIIC ONO- ANDSS SI TIC WITH OCCASIONAL ACS3 ROC'S
XIST RAIWEE A"' "r T" AIDDELD 01 POEM'S
F OW UPPER t (SANTA MONICA MOUNTAINS)
IN !RIMY. of PRANHE AND arISNOCIONITE
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CATALINA RCUIST COMPARES NILE ERANCISCAN IONISATION
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PITH QUARTZ VEINS
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U-UPTHROWN SIDE; D-DOWNTHROWN 310E1
CONCEALED FAULT
ANTICLINE (DASHED WHERE APPROXIMATLY
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SYNCLINE (DASHED WHERE APPROXIMATLY
LOCATED.
CONTACT (DASHED WHERE APPROXIMATLY
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• AD WELLS USED IN PREPARATION OF GEOLOGIC
SECTIONS.
A AI LINE LOCATION OF GEOLOGIC SECTIONS SHOWN
ON PLATES GA THROUGH GO
RCS F I GU R E 4B
G EN ER A LI ZED G E O L O G I C M A P
LEG E N D & S Y M BO LS
RC S Job No. 462-L ASOC June 2018
Adapted from DWR (1961)
RI CHAR D C. SL ADE & ASSOCI ATES L LC
CONSULTING GROUNDWATER GEO LOGIST S
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
SYSTEM SERIES FORMATION LITHOLOGY AQUIFER AND
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PLEISTOCENE LAKEWOOD 5,7,1::.,ARTESIA
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LOCAL UNCONFORMITY *DESIGNATIONS AND TERMS UTILIZED IN
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- "REPORT OF REFEREE" DATED JUNE 1952
- - - - - PREPARED BY THE STATE ENGINEER
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UPPER PICO PICO o o• o o o OC, no cz, o o o p p 0n?P', UNDIFFERENTIATED }DESIGNATED AS "WATER BEARING ZONES"
PLIOCENE FORMATION - -- - - FORMATION IN ABOVE NOTED REPORT OF REFEREE
RCS F I G URE 5
G E N E R A L I Z E D S TR AT IG R A P H IC S EC TI O N
F OR TH E C O A S TA L P L A IN O F LO S A N GE L E S C O UN T Y
RC S Job No. 462-L A SOC June 2018
Miralom
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RICHA RD C. SLADE & ASSOC IATES LLC
CO NSULTING GRO UNDWATER GEOLOG ISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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SANTA'MONICA
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Q Key Well with Hydrograph Data
II] Rain Gages
IMML City Boundary
Name and approximate Boundary of Groundwater Basin
(as defined by DWR Bulletin 118 Update 2003)
Subbasin Boundary by Others
Approximate Fault Zone
Watershed Boundary for Santa Monica Bay Region,
arrows show general direction of surface water runoff
oft = (as defined by the Caliomia Interagency Watershed Map of 1999, updated 2004)
Surface Water Outflows Along Streams
and Creeks from Watershed Region
C:53:123
ArcadiaP.1 o. 4.
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H O L L Y W O O D F A U L T
H O L L Y W O O D F A U L T
H O L L Y W O O D F A U L T
H O L L Y W O O D F A U L T
H O L L Y W O O D F A U L T
H O L L Y W O O D F A U L T
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S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
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S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
S A N T A M O N I C A F A U L T
SANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULTSANTA MONICA FAULT
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
B R E N T W O O D F A U L T
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HOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOODHOLLYWOOD
GROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASINGROUNDWATER BASIN
CENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRAL
GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER
BASINBASINBASINBASINBASINBASINBASINBASINBASIN
I-10I-10I-10I-10I-10I-10I-10I-10I-10
CrestalCrestalCrestalCrestalCrestalCrestalCrestalCrestalCrestal
SubbasinSubbasinSubbasinSubbasinSubbasinSubbasinSubbasinSubbasinSubbasin
I-10I-10I-10I-10I-10I-10I-10I-10I-10
WEST COASTWEST COASTWEST COASTWEST COASTWEST COASTWEST COASTWEST COASTWEST COASTWEST COAST
GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER
BASINBASINBASINBASINBASINBASINBASINBASINBASIN
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O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
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SANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICA
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SANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICA
GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER
BASINBASINBASINBASINBASINBASINBASINBASINBASIN
Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2Arcadia No. 2
Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3Santa Monica No. 3
Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4Arcadia No. 4
Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5Arcadia No. 5
Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6Santa Monica No. 6
Colorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial ParlColorado Yard/Memorial Parl
City Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall WellCity Hall Well
Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8Santa Monica No. 8
Marine Park WellMarine Park WellMarine Park WellMarine Park WellMarine Park WellMarine Park WellMarine Park WellMarine Park WellMarine Park Well
Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1Saltwater No. 1
Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1Airport No. 1
Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2Saltwater No. 2
Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7Santa Monica No. 7
Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4Santa Monica No. 4
Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18Charnock No. 18
Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16Charnock No. 16
Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13Charnock No. 13
Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20Charnock No. 15 & 20
Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19Charnock No. 19
Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5Santa Monica No. 5
Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1Santa Monica No. 1
Santa Monica Santa Monica Santa Monica Santa Monica Santa Monica Santa Monica Santa Monica Santa Monica Santa Monica
Rain GageRain GageRain GageRain GageRain GageRain GageRain GageRain GageRain Gage Culver City Culver City Culver City Culver City Culver City Culver City Culver City Culver City Culver City
Rain GageRain GageRain GageRain GageRain GageRain GageRain GageRain GageRain Gage
UCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain GageUCLA Rain Gage
Getty Museum Getty Museum Getty Museum Getty Museum Getty Museum Getty Museum Getty Museum Getty Museum Getty Museum
Rain GageRain GageRain GageRain GageRain GageRain GageRain GageRain GageRain Gage
LAX Rain GageLAX Rain GageLAX Rain GageLAX Rain GageLAX Rain GageLAX Rain GageLAX Rain GageLAX Rain GageLAX Rain Gage
Richard C. Slade & Associates LLC
14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401
Phone: (818) 506-0418 Fax: (818) 506-1343
Figure 6
Map of Watershed
and Local Drainage
Consulting Groundwater Geologists
Date:
June 2018
Project No:
462-LASOC
Author: LAB/JA
Projection: Custom Projection
Filename:
Figure 12
Legend
City Well
Key Well with Hydrograph Data
Name and approximate Boundary of Groundwater Basin
(as defined by DWR Bulletin 118 Update 2003)
City Boundary
Rain Gages
Subbasin Boundary by Others
Approximate Fault Zone
Watershed Boundary for Santa Monica Bay Region,
arrows show general direction of surface water runoff
(as defined by the Caliornia Interagency Watershed Map of 1999, updated 2004)
Surface Water Outflows Along Streams
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F IG U R E 7
G R O U N D WATE R EL E VAT IO N C ON TO U R S
O F T H E W E S T C O A S T & C E N T R A L
G R OU N D WAT E R B A S I N S
RIC HARD C. SLA DE & ASSOCI ATES LLC
CONSULT ING GROUN DWATER GEOLOGI STS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com R CS Job No. 462-LA S O C June 2018
45
40
35
30
25
20
15
10
5
IN Yearly Rainfall Totals Santa Monica Pier (AVG. 10.91)
• Yearly Rainfall Totals LAX (AVG. 11.77)
• Yearly Rain Fall Totals Culver City (AVG. 12.02)
Yearly Rainfall Totals UCLA (AVG. 16.22)
0 AAP
I
1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020
■
Calendar Year
FIGURE 8A
ANNUAL RAINFALL TOTALS
VARIOUS RANGE GAGES
RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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2020
Job No. 462-LASOC June 2018
1000
800
600
400
200
0
-200
-400
- - - - --- -- ----- ----- II
Accumlated Departure Santa Monica Pier (AVG. 10.91 inches)
Accumlated Departure Culver City (AVG. 12.02 inches)
Accumlated Departure LAX (AVG. 11.77 inches)
Accumlated Departure UCLA (AVG. 6.22 inches)
MIME
MIME
111111111
111111111
111111111
_ - _J111111111
111.1111111111111111111111111111111111111111111
11111111111111111111111111111111111111111111111
111111111111111111.1111111111111111111111111111 11111111111.1111111111111111111011111111
111121111111111111111111.11111111111111111111111411111111111111111W112111111111011111111
111.11111111111111111111.1111111111111111111111101111111111111111M1111111111111111111111
111.11111111111111111111.11111111111111011EA1111:31111211111111/111111111111111111111111
111111111111111111.1111111111111111,1W4OVAIMU1110.411111.1111q111111111111111111111111
VA111111111111111111.1111111111111111M INI i010f11111WW11.11FT1111111111111111111111111
1111111111111V ,%11111111111111111111111U111111041111111CillAIIIN11111111111111111110111111
111111111ffrAM1111111111P111111,460111111101T111111111L1M1111111111111111111L111111
11111111E1U11100111111111% 1WAMNii1111111111410111111111M11111111111111111,111A11111
111111P4,411111LIOINV1 W 401V V/111111111111111110411111.1111111101F11E1111,11111111
1111111:4111111101V.111111W1M1111111111111111111011111111111111UJIMAPm4M111111
111111h111111111VtINVIWAIIN11111111111111111110,413111111111111A1WWIMAVIV1111
11111/11111111111MAIMIllid111111111111111111111111111111111rIlinliA111111M111111
1111r411111111111.11111111111111111111111111111111Wk11111111141411111111111111L111111
IIIIPM1FiAlIVI111111111111111111111111111111111111111W1111111FUT11111111111111111.01041
IllAWNIILZlidV411111111111111111111111111111111111111111.11/0A1111111111111111116411
11111,111111111111111411111111111111111111111111M/0111 111571/411111111111111111111111
1111111111111111L211F1,11M41111111111,111111111E11WW_ 01,411111111111111111111111111
1111111111111111110A/NWn1411111111/41111,1111,11111.111AtiVA1111111111111111111111111
1111111111111111111ii11111110,91F1,17:1MK11101,111111t$111 111111111111111111111111111
111111111111111111111111111111-AWFALWILIOPUIVIUM11111r111111111111111111111111111
1111111111111111111111111111111111111111WVW111111111 111111111111111111111111111111
11111111111111111111111111111111111111111111111111111111 111111111 11111111111
111111111111111111111111111111111111111111111111111111110.momm IIIIIII011
1111111111111111111111111111111111111111111111111111111111111111111 11111111111
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1111111111111.11111111111111141111111111111
11111111111.111111111111111A1111111111111
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111111111111111111111FINNOPAIL111111111111
111111112111111111111VIJWIIIL11111111111
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1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2,f71 f,7 2015 2020
Alt FIGURE 8B
ACCUMULATED DEPARTURE OF RAINFALL
Job No. 462-LASOC June 2018
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Calendar Year
“Dry”“Wet”“Wet”“Wet”“Dry”“Dry”
“Hydrologic Periods”
Selected
Baseline Period
RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
1000
800
600
400
200
0
-200
-400
I
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111111111111111111111111111111111111111111111111111111111111111111MIJW1111111111111111
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1111111111111111111111111111111111111111111111111111111111111111111111111111111k1111111111
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1111111111111111111111111111111111111WWFA11,1111041111111111q1111111111111111111111111
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111111111111111111116111111110M V17:1BAk111Ar1,111111111V1111111111111111111111111111 111111111111111111111111111111I -AeMAAM111L1WAI1IIIIIIM1111111111111111111111111111 111111111111111111111111111111111 1111111Wellad1111111111111111111111111111111111111111
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Accumlated Departure Santa Monica Pier (AVG. 10.91 inches)
Accumlated Departure Culver City (AVG. 12.02 inches)
Accumlated Departure LAX (AVG. 11.77 inches)
—0— Accumlated Departure UCLA (AVG. 6.22 inches)
'1111111111111111111011111111111111111111111111:111
111111111111111111111111111111111111111111111111111
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1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020
RCS FIGURE 9
SELECTED BASELINE PERIOD
Job No. 462-LASOC June 2018
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Calendar Year
“Hydrologic Baseline Period”
RICHARD C. SLADE & ASSOCIATES LLC
CONSULTING GROUNDWATER GEOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
I I ' I
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• •
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•
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1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1 1 I 1 1 1
Year
RCS
^-,,%........'"........-.----"..-7
F IGUR E 10A
A R CAD IA W E L LF IEL D/S UB B AS I N
H YD R O GR A P H S
Job No. 462-L ASOC June 2018
RICH ARD C. S LAD E & A SSO CIAT ES LLC
CONSULTING GROUND WAT ER G EOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, C A 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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-4 00 .0 0
-3 00 .0 0
-2 00 .0 0
-1 00 .0 0
0.0 0
10 0.00
20 0.00
30 0.00
40 0.00
50 0.00
60 0.000
50
10 0
15 0
20 0
25 0
19 30 19 35 19 40 19 45 19 50 19 55 19 60 19 65 1970 19 75 19 80 19 85 19 90 19 95 20 00 20 05 20 10 2015 20 20
KÑMǾ
Arcad ia We ll No . 2 SWL Mea su re men ts
Arcad ia We ll No . 4 SWL Mea su re men ts
Arcad ia We ll No . 5 SWL Mea su re men ts
San ta Monica W ell No . 1 SW L Me asure men ts
San ta Monica W ell No . 5 SW L Me asure men ts
Accu mula te d De pa rtur e of Ra infall - Culver City Ga ge
I
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1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Year
RCS
-..______----.. --------:
F IG UR E 10B
C HA R NO CK W E L LF IEL D/S UB B AS I N
HYDR OGRA P H S
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Job No. 462-L A SO C June 2018
RICHA RD C. SLADE & ASSOC IATE S LLC
CONSULTIN G GROUNDWATER GEOLOG ISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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-4 00
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19 30 19 35 19 40 19 45 19 50 1955 19 60 19 65 19 70 19 75 19 80 19 85 1990 19 95 20 00 20 05 20 10 20 15 20 20
KÑMǾ
C har no ck We ll No. 7 SWL Measu rem ents Char no ck Well N o. 13 SW L Mea sure men ts
C har no ck We ll No. 15 SW L Mea sure men ts Char no ck Well N o. 16 SW L Mea sure men ts
C har no ck We ll No. 18 SW L Mea sure men ts Char no ck Well N o. 19 SW L Mea sure men ts
C har no ck We ll No. 20 SW L Mea sure men ts Accu mula te d De pa rtur e of Ra infall - Culv er C ity Ga ge
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Year
RCS F IGU R E 10C
O LY MP I C WEL L FI E LD/S U BBA S IN
H YD R O GR A P HS
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Job No. 462-L A SO C June 2018
R ICHARD C. SLADE & A SSOC IATES LL C
C O NSU LTI NG GR O UNDWATER GEOLO GIS TS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
-4 00 .0 0
-3 00 .0 0
-2 00 .0 0
-1 00 .0 0
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50 0.00
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10 0
15 0
20 0
25 0
19 30 19 35 19 40 19 45 19 50 19 55 19 60 19 65 19 70 19 75 19 80 19 85 1990 19 95 20 00 20 05 2010 20 15 20 20
Year
San ta Monica Well No . 3 SW L Me as ure men ts
San ta Monica Well No . 4 SW L Me as ure men ts
San ta Monica Well No . 7 SW L Me as ure men ts
Ac cu mula te d Ra infall Depa rture - Culver City Ga ge
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20 -
30 -
40
50
60
70
80
90
100
110
120
130
140 -
150 -
160
170
180
190
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Accumulated Rainfall Departure - Culver City Gage
600.00
500.00
400.00
300.00
200.00
100.00
0.00
-100.00
200.00
300.00
200 400.00
1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
RCS F IG UR E 11A
KE Y W E LL H Y DROG RAPH
SAN TA M O N I C A WEL L NO. 5
A RC A D I A S UBB A S IN, TOTAL C HA N G E IN S TO R AG E
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Well Schematic
(Depth=ft bgs)
Note: Reference Point = 378.08 ft above msl
0 ft
T.D.=255 ft bgs
Blank
Casing
Perforated
Intervals:
145-235
ft bgs
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Job No. 462-L ASOC June 2018
RICH ARD C. S LAD E & ASSO CIAT ES LLC
CONSULTING GROUND WAT ER G EOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, C A 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
Δ S = -8 ft
30-year Baseline Peiod
Year
600.00
10
500.00 20
400.00
30
40
50
60 300.00
200.00
70
80
90 0
100.00 100
110
0 00 120
130
140 -100.00
150
0
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170
-200.00
-300.00 180
190
200
= 0
0 Static Water Level Measurement
Accumulated Rainfall Departure - Culver City Gage
-400.00
1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
RCS F IGU R E 11B
KEY WE LL HY DR OG RA PH
CH A RN OC K WEL L NO. 16 & NO. 20
C H AR N O C K SU B BASI N, TO TA L C H ANGE I N STOR A G E
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T.D.=410 ft bgs
Well Schematic
(Depth=ft bgs)
Blank
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220-390
ft bgs
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at
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Note: Reference Point = 105.83 ft above msl
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ΔS = +12 ft
P
P= pumping level or incomplete
recovery measurement
30-year Baseline Peiod
Job No. 462-LA S O C June 2018
RICHARD C. SLADE & ASS O CIAT ES LLC
CONSULTING GROUND WAT ER GEOLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, C A 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
Well No. 20
Measurements
Year
0 600.00
10
20
30
40
50
500.00
400.00
60 • 300.00
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so -wow nom I
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100 ==
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130
140
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•••Accumulated Rainfall Departure - Culver City Gage
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200.00
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1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
RCS
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T.D.= 564 ft bgs
Well Schematic
(Depth=ft bgs)
Blank
Casing
Perforated
Interval:
200-544
ft bgs
Note: Reference Point = 150.46 ft above msl
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ΔS = -30 ft
FI G U RE 11C
K E Y W EL L H YD R O GR A P H
S A NTA M ON IC A W E LL N O. 7
OLY M P I C S UB B A S I N, TOTAL CHA N G E I N S TO RAGE
P
P= pumping level or incomplete
recovery measurement
P
30-year Baseline Peiod
Job No. 462-L ASOC June 2018
RICHA RD C. SLADE & ASSOCIATE S LLC
CON SULTIN G GROU NDWATE R GE OLOGISTS
14051 Burbank Blvd., Suite 300
Sherman Oaks, CA 91401
Southern California (818) 506-0418
Northern California (707) 963-3914
www.rcslade.com
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O U T F L O W
O U T F L O W
O U T F L O W
O U T F L O W
O FOFOFOFOFOFOFOFOF
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
S U R F A C E
W A T E R
W A T E R
W A T E R
W A T E R
W A T E R
W A T E R
W A T E R
W A T E R
W A T E R
I-
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SANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICA
MOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINSMOUNTAINS
SANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICASANTA MONICA
GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER
BASINBASINBASINBASINBASINBASINBASINBASINBASIN
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
O l y m p i c S u b b a s i n
Arcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia SubbasinArcadia Subbasin
Legend
Santa Monica City Boundary
Name and approximate Boundary of Groundwater Basin
(as defined by DWR Bulletin 118 Update 2003)
14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401
Phone: (818) 506-0418 Fax: (818) 506-1343
Consulting Groundwater Geologists
Richard C. Slade & Associates LLC
Figure 12
Usable Areas of
Groundwater
Storage Subunits
Date:
June 2018
Projection: Custom Projection
Author: LAB/JA
Project No:
462-LASOC
Filename:
Figure 12
Watershed Boundary for Santa Monica Bay Region,
arrows show general direction of surface water runoff
(as defined by The California Interagency Watershed Map of 1999,
updated 2004)
Surface Water Outflows Along Streams
and Creeks from Watershed Region
Approximated Fault Zones
Note: Faults and subbasins within Santa Monica Groundwater Basin not shown hereon.
Approximate Usable Storage Subunit Boundary
101
Miles
RCS
APPENDIX 2
TABLES
TABLE 1
SUMMARY OF WELL CONSTRUCTION DATA
FOR HISTORIC AND EXISTING CITY WELLS USED IN THIS STUDY
Well
No.
State
Well No.
State Well
Completion
Report No.
(E-log Date)
Date
Constructed
Method
of
Drilling
Pilot Hole
Depth
(ft)
Casing Type
& Depth
(ft)
Casing
Diameter
(in)
Borehole
Diameter
(in)
Sanitary
Seal
Depth
(ft)
Perforation
Intervals
(ft)
Type of
Perforations
Slot Opening
of
Perforations
(in)
Type of
Gravel
Pack
Current
Status
Santa Monica No. 1 1S/15W-31E1 31208 4/1966 Cable Tool 283 Steel, 250 14 14 None I5I-250 Moss hydraulic
louvers
0.158
(5/32")None Active
Santa Monica No. 5
(AKA La Mesa Well)2S/15W-30P1 093782
(E-log dated 6/1/80)6/1980 Reverse
Circulation 290 Steel, 255 14 30 50 145-235 louvers 0.094
(3/32")minus 3/8"Observation Well
Santa Monica No. 6 1S/15W-32E2 093781
(E-log dated 6/11/80)6/1980 Reverse
Circulation 160 Steel, 140 20 30 50 80-120 louvers 0.094
(3/32")3/8"Destroyed in 1980s
Arcadia No. 2 1S/15W-32A2 2535F 4/1940 Cable
Tool 250 Steel
250 16 to 14 16 none 38-52
162-210
Moss hydraulic
knife cut
0.75
(3/4")none Destroyed
1962 or 1967?
Arcadia No. 4 1S/15W-32A5 90447 8/1964 Cable
Tool 235
Original: Steel to 235
Casing Liner: Low Carbon Steel to
225
14
Liner: 12 14 none 85-218
Liner: 110-215
Moss hydraulic
louvers
Liner: wire-
wrapped screen
0.125
(1/8")
Liner: 0.090
None Active; Casing liner added in
2000
Arcadia No. 5 1S/15W-32A6 294163
E-log performed but
not found
3/1989 Mud
Rotary 250
Original: Steel, 250
Casing Liner: Low Carbon Steel to
238
16
Liner: 12 30 120 122-222
Liner: 110-235
louvers
Liner: wire-
wrapped screen
0.094
(3/32")
Liner: 0.090
#5 Active; Casing liner added in
2000 (?)
Charnock No. 13 11C17 31233 9/1966 Direct
Rotary 423
Original: Steel to 410
Casing Liner: 304L Stainless Steel
to 200 ft
16
Liner: 14
No
Data 49 200-390
Liner: 197-388
louvers
Liner: wire-
wrapped screen
0.125
(1/8)
Liner: 0.040
ND Active; casing liner added in
1991
Charnock No. 16 11C19 093780 7/1980 Reverse
Circulation 430 Steel, 410 20 30 190 220-390 louvers 0.094
(3/32)
3/8"
minus active
Charnock No. 18 11C22 229720 5/1984 Reverse
Circulation 480 Steel, 480 18 30 100 240-455 wire-wrapped
screen 0.050 Monterey
6X12 & 8X16 active
Charnock No. 19 11C21 294165 11/1988 Reverse
Circulation 550 Steel, 510 18 30 150 200-450 louvers 0.094
(3/32)#5 LG active
Charnock No. 20 11C23(?)e0160867 9/2012 Reverse
Circulation 450 304 Stainless Steel, 405 16 26 150 242-295
315-385 louvers 0.065 Tacna 6x20 active
Santa Monica No. 3 2S/15W-4C2 50813
(E-log dated 9/16/69)10/1969 Reverse
Circulation 570
Original: Steel to 550
Casing Liner: 316L Stainless Steel
to 498
16
Liner
14 to 297
12 to 498
28 50
210-270, 300-380
410-430, 490-530
Liner: 207-498
louvers
Liner: wire-
wrapped screen
0.125
(1/8")
Liner: 0.040
minus 3/8"Active; Casing liner added in
2014
Santa Monica No. 4 2S/15W-4A1 093785
(E-log dated 12/6/81)12/1981 Reverse
Circulation 560 Steel, 560 20 32 200(?)200-410
470-540 louvers 0.094
(3/32")#4 & #5 Active
Santa Monica No. 7 1S/15W-30P1 21833
(E-log dated 8/28/82)11/1982 Reverse
Circulation 530 Steel, 564 16 28 100 200-544 louvers 0.094
(3/32")#5
Destroyed 4/2018
(formerly located 100 ft east of
new well SM-8
Santa Monica No. 8 N/A N/A
(Elog dated 11/7/2017)4/2018 Reverse
Circulation 600 Type 304L Stainless Steel
480 14 28 to 210
24 to 490 150
210-265
295-325
335-345
360-460
Ful-flo
louvers 0.060 6 X 20 Inactive
(awaiting equipping)
Salt Water No. 1 2S/15W-7Q1 40854 11/1967 Reverse Circulation 140 304 Stainless Steel
120 12 24 20 60-120 louvers 0.125
(1/8")ND Inactive
Salt Water No. 2 2S/15W-7Q2(?)50802
E-log performed but not available.5/1969 Reverse Circulation 186 304 Stainless Steel (?)
120 12(?)ND 20 20-120 louvers 0.125
(1/8")ND Abandoned
Marine Park Well 2S/15W-9N9 E-log performed but not available 4/1970 Mud
Rotary 180 Steel (?), 156 4 ND ND 125-135 ND ND ND Observation Well
Colorado Yard/Memorial Park
Groundwater Monitoring Well N/A N/A
E-Log dated 10/10/2017 11/2017 Reverse
Circulation 607 Schedule 80 PVC 6 16 60 85-245 slotted
screen 0.032 8 X 16 Observation Well
City Hall Well No. 1 N/A N/A
(E-log dated 9/24/16)11/2016 Mud
Rotary
652
backfilled to 180' with
10.3-sack cement
PVC 6 16¼50 60-90
120-160
slotted
screen 0.030 8 X 16, 50'-100'
16 X 30,110'-180'
Inactive
(awaiting equipping)
Airport Well N/A N/A
(E-log dated 10/6/17)4/2018 Reverse
Circulation 600 Type 304L Stainless Steel
610 14 28 to 190
24 to 622 139
190-245
440-490
505-530
560-590
wire-wrapped
screen 0.035 10 X 30 Inactive
(awaiting equipping)
Notes:ND = No data
N/A = data available (not listed) on log
Arcadia Subbasin
Olympic Subbasin
Coastal Subbasin
Charnock Subbasin
*Prior to construction of Well No. 2 in 1940, there were a total of nine wells constructed at the Arcadia plant dating back to 1903 and records for these wells are sparse.
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
June 2018
TABLE 2
GROUNDWATER PRODUCTION FROM CITY WELLS AND OTHER WELLS
(1988 THROUGH 2017)
ARCADIA(1)OLYMPIC
CITY
WELLS
CITY
WELLS
GOLDEN STATE
WATER COMPANY TOTAL CITY
WELLS
1988 372 8,111 570 8,681 387 9,441
1989 357 6,363 570 6,933 457 7,747
1990 389 4,132 570 4,702 469 5,560
1991 417 4,728 570 5,298 387 6,101
1992 396 6,486 570 7,056 981 8,432
1993 390 6,153 570 6,723 2,867 9,979
1994 419 5,906 570 6,476 3,126 10,020
1995 542 6,322 570 6,892 3,176 10,609
1996 370 2,284 570 2,854 3,044 6,267
1997 0 0 0 0 2,820 2,820
1998 0 0 0 0 2,642 2,642
1999 0 0 0 0 2,937 2,937
2000 0 0 0 0 2,912 2,912
2001 387 0 0 0 2,809 3,196
2002 467 0 0 0 1,824 2,291
2003 455 0 0 0 593 1,047
2004 137 0 0 0 385 522
2005 395 0 0 0 1,495 1,890
2006 387 0 0 0 1,365 1,752
2007 374 0 0 0 1,619 1,993
2008 360 0 0 0 1,663 2,023
2009 340 0 0 0 1,722 2,062
2010 290 593 0 593 2,436 3,320
2011 447 5,168 0 5,168 2,317 7,932
2012 450 5,277 0 5,277 2,636 8,363
2013 434 7,824 0 7,824 1,609 9,867
2014 714 8,377 0 8,377 1,591 10,682
2015 620 8,114 0 8,114 1,961 10,695
2016 698 8,311 0 8,311 1,992 11,001
2017 708 7,585 0 7,585 1,720 10,013
TOTAL PRODUCTION (Per Subbasin) 11,310 101,730 5,130 106,860 55,940 174,120
TOTAL AVERAGE PRODUCTION (AFY)* 440 1,860 8,590**
TOTAL ESTIMATED (AF)* 9,300
TOTAL AVERAGE (AFY) 310
TOTAL ESTIMATED (AF)* 7,800
TOTAL AVERAGE (AFY) 260
AVERAGE ANNUAL PRODUCTION/EXTRACTIONS
(AFY)*1,010 1,860 5,800
(over all 30 years)
NOTES:
NA = Not applicable
CHARNOCK(2)
TOTAL
PRODUCTION
(Extractions
Per Year)
6,290
** This number respresents the average for only those years in which the wells were pumping.
TOTAL ESTIMATED GROUNDWATER PRODUCTION BY SUBBASIN
(in AF)
SUBBASIN
YEAR
1. 2001 groundwater production from Arcadia Wellfield could instead be 353 AF, per email to RCS from Ms. Myriam Cardenas
formerly of the City of Santa Monica, 1/7/2013
3. City has had no wells in the Coastal or Crestal subbasins of the SMGB; it is known that LACC does have active irrigation-supply wells in the Coastal subbasin.
* Numbers rounded to nearest 10. For the Arcadia and Charnock subbasins, the average does not count those years for which no pumping was conducted
(i.e., zero extraction years).
RIVIERA GOLF COURSE (TOTAL AF)
BRENTWOOD GOLF COURSE (TOTAL AF)
6,290
2. Based on preliminary data submitted by third party well ownder, an average value of 570 AFY was calculated for that water company's extractions until its wells were
removed from service at end of 1996.
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462‐LASOC
June 2018
TABLE 3
PRELIMINARY CALCULATIONS OF CHANGE IN GROUNDWATER IN STORAGE
DURING BASELINE PERIOD FOR THE
ARCADIA, CHARNOCK AND OLYMPIC GROUNDWATER SUBBASINS
Usable Surface Area of Subbasin (mi2)
Estimated Range of Specific Yield of Sediments 8% to 12%
Static Water Level at Beginning of Baseline Period (ft bgs)
Static Water Level at End of Baseline Period (ft bgs)
Change in Static Water Level for Baseline Period (ft)
Change in Groundwater in Storage in Subunit (AF)*-2,700 to -4,100
Average Annual Change in Storage (AFY)-90 to -140
Usable Surface Area of Subbasin (mi2)
Estimated Specific Yield of Sediments 12% to 18%
Static Water Level at Beginning of Baseline Period (ft bgs)
Static Water Level at End of Baseline Period (ft bgs)
Change in Static Water Level for Baseline Period (ft)
Change in Groundwater in Storage in Subunit (AF)*3,400 to 5,100
Average Annual Change in Storage (AFY)120 to 180
Usable Surface Area of Subbasin (mi2)
Estimated Specific Yield of Sediments 10% to 15%
Static Water Level at Beginning of Baseline Period (ft bgs)
Static Water Level at End of Baseline Period (ft bgs)
Change in Static Water Level for Baseline Period (ft)
Change in Groundwater in Storage in Subunit (AF)*-5,900 to -8,800
Average Annual Change in Storage (AFY)-200 to -300
TOTAL CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*:-5,200 to -7,800
TOTAL AVERAGE CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*:-170 to -260
*Numbers rounded to nearest 10 AF
3.1
ARCADIA GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA
MONICA WELL NO. 5 (FIGURE 11A)
6.6
130
138
-8
CHARNOCK GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH CHARNOCK
WELL NO. 16 (FIGURE 11B)
3.7
158
146
12
OLYMPIC GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA
MONICA WELL NO. 7 (FIGURE 11C)
118
148
-30
Note: See text section Titled "Subunit/Subbasin Changes in Groundwater in Storage Calculations," for explanation
and derivation of parameters and values.
The resulting change in storage values in each of the three columns on the right side of the table result from using the
"estimated range of specific yields of sediments" for each subunit.
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
May 2018
TABLE 4
UPDATED, PRELIMINARY CALCULATIONS OF SUSTAINABLE YIELD
THREE SANTA MONICA SUBBASINS
SUBBASIN
AVERAGE ANNUAL
EXTRACTIONS
DURING
BASELINE PERIOD
(AFY)*
Arcadia -90 to -140 1,010 870 to 920
Charnock 120 to 180 6,290 6,410 to 6,470
Olympic -200 to -300 1,860 1,560 to 1,660
TOTALS*:-170 to -260 9,160 8,840 to 9,050
Note:
AVERAGE
ANNUAL CHANGE
IN STORAGE
DURING
BASELINE PERIOD
(ΔS in AFY)
UPDATED
RANGE OF
SUSTAINABLE
YIELD
(AFY)*
City has no wells in Crestal or Coastal subbasins and, thus, these subbasins are
not considered herein.
*Numbers rounded to nearest 10 AF
Updated Preliiminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
June 2018
TABLE 5
COMPARISON OF CALCULATED SUSTAINABLE YIELD VALUES
SANTA MONICA SUBBASINS
SMGB
SUBBASIN
PREVIOUS
STUDIES
(AFY)
Arcadia(1)870 to 920 2,000 (2, 3)
Charnock 6,410 to 6,470 4,420 to 7,500(4)
and 8,200(5)
Olympic 1,560 to 1,660 3,275(3)
Coastal(6)1,160 to 1,450 4,225(3)
TOTALS: 10,000 to 10,500 13,920 to 17,700
Crestal 2,000(7)
TBD = To Be Determined.
CURRENT
(UPDATED)
STUDY
(AFY)
Notes/Sources of the numbers:
TBD
7) This is the midpoint value of the LADWP (1991) assigned value of 1,000 to 3,000 AFY
2) City (August 23, 1991)
1) The number derived for the Arcadia subbasin is for all wells pumping in this subbasin and
does not necessarily reflect what is available to the City for future pumpage
3) RCS March 27, 2013
4) From KJC, June 1992, for the combined Arcadia, Olympic & Charnock subbasins.
5) From Komex, 2001; this Komex value was accepted by RCS in its March 2013 Memorandum.
6) This value estimated based on testing of Airport Well No. 1 in April 2018
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
June 2018
TABLE 6
POTENTIAL SUSTAINABLE YIELD VALUES
SANTA MONICA SUBBASINS
GROUNDWATER
SUBBASIN
PREVIOUS
STUDIES
(AFY)
Arcadia(1)870 to 920 870 to 920 2,000 (2, 3)
Charnock 6,410 to 8,080 6,410 to 8080(6)4,420 to 7,500(4)
and 8,200(5)
Olympic 1,560 to 1,660 800 to 1,000 2,360 to 3145(6)3,275(3)
Coastal(7)1,160 to 1,450 1,160 to 1,450 4,225(3)
TOTALS: 10,000 to 12,110 10,800 to 13,595 13,920 to 17,700
Crestal 2,000(8)
CURRENT
(UPDATED)
STUDY
(AFY)
8) This is the midpoint value of the LADWP (1991) assigned value of 1,000 to 3,000 AFY
TBD
Notes/Sources of the numbers:
1) The number derived for the Arcadia subbasin is for all wells pumping in this subbasin and does not necessarily reflect what is available to the City for future pumpage
2) City (August 23, 1991)
3) RCS March 27, 2013
ARTIFICIAL
RECHARGE
(AFY)
TBD
NA
TBD
TOTAL POTENTIAL
SUSTAINABLE YIELD
(AFY)
NA
4) From KJC, June 1992, for the combined Arcadia, Olympic & Charnock subbasins.
5) From Komex, 2001; this Komex value was accepted by RCS in its March 2013 Memorandum.
NA
7) This value estimated based on testing of Airport Well No. 1 in April 2018
6) This value was adjusted in accordance with previous estimates.
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
June 2018
TABLE 7
POTENTIAL LOWER AND UPPER
SUSTAINABLE YIELD VALUES
SANTA MONICA SUBBASINS
GROUNDWATER
SUBBASIN
LOWER
LIMIT
(AFY)
UPPER
LIMIT
(AFY)
PREVIOUS
STUDIES(1)
(AFY)
Arcadia 870 920 2,000
Charnock(2)6,410 8,080 4,420 to 8,200
Olympic(3)2,360 3,145 3,275
Coastal(6)1,160 1,450 4,225
Crestal NA NA 2,000
Subtotals:10,800 13,595 15,920 to 19,700
ICF Recharge Factor:1,000 1,130 NA
TOTALS:11,800 14,725 15,920 to 19,700
2) Upper Limit based on potential pumping from GSWC Charnock Well No. 10 and
Komex Analysis (see Komex, 2001, pg. 85 2nd paragraph, see Appendix 3)
3) Based on Well No. 3 Replacement and SWIP injection on this subbasin.
Notes/Sources of the numbers:
1) See Table 6 for explanation of these previous values.
Updated Preliminary Study of the
Sustainable Yield of the Groundwater Subbasins
Within the Santa Monica Basin
RCS Job No. 462-LASOC
May 2018
RCS
APPENDIX 3
ICF MAY 25, 2018 MEMORANDUM
1 Ada Parkway, Suite 100, Irvine, CA 92618 USA +1.949.333.6600 +1.949.333.601 fax icf.com
Memorandum
To: Tom Watson, PG, City of Santa Monica
From: Gary Clendenin, PG, ICF
Norm Colby, PG, CHg, CGC Environmental, Inc.
Date: May 25, 2018
Re: Evaluation of Recharge and its Effect on Sustainable Yield in the Santa Monic Basin
Introduction
The City of Santa Monica (City) has been a leader among California cities in sustainably managing
its available water resources. Sustainable management involves the practice of balancing water
demands with water supply. The City has set an objective of eliminating its reliance on
environmentally costly imported water by 2020. To achieve and maintain this goal the City’s strategy
for adaptive management must consider the vagaries of climate change, population growth, and
future development. Recognizing these challenges, the City has engaged in forward thinking
conservation policies and programs to reduce demand and enhance its water treatment technology
to develop more potable water out of its current supply. The City has also conducted several studies
over the past several years to more precisely quantify the amount of water in the Santa Monica
Basin (SMB) that can be pumped sustainably. To estimate that volume it is imperative to know how
much water is entering the basin as recharge (inflow).
The purpose of this memorandum is to evaluate the amount of water that may be added to the SMB
resulting from direct recharge and mountain-front recharge and ultimately to assess the effect this
recharge may have on previously calculated sustainable yield estimates. This remainder of this
memorandum includes a background, analysis of available data, and findings and conclusions.
Background
The City supplies potable water to approximately 93,000 residents covering an area of 8.3 square
miles. In 2011, the Santa Monica City Council adopted a goal of water self-sufficiency by eliminating
reliance on imported water from the Metropolitan Water District of Southern California (MWD) by
2020. The City currently imports approximately 30% of its total annual demand from the MWD.
In 2014, the City retained Kennedy/Jenks Consultants (KJ) to develop an integrated Sustainable
Water Master Plan (SWMP). The SWMP combined relevant components of existing plans with an
evaluation of a broad range of water supply and demand management options to assist the City in
1 Ada Parkway, Suite 100, Irvine, CA 92618 USA +1.949.333.6600 +1.949.333.601 fax icf.com
meeting its goals. The KJ report included an analysis of supply and demand management options to
cost effectively reduce future water use and mechanisms to enhance local water supply production
capabilities. In 2017, the City retained Black & Veatch Corporation (BV) to begin the process of
updating the SWMP. A key consideration in developing long-term water management options is a
detailed understanding the hydrogeolgy of the SMB, including the basin-wide sustainable yield.
Sustainable yield is generally defined as the rate at which groundwater can be pumped perennially
under specified operating conditions without causing an undesired result. Sustainable yield is
typically is expressed in units of acre-feet (AF) which are equivalent to approximately 326,000
gallons.
Historically, the City has funded several studies to evaluate sustainable yield, including a recent
study 1 to update previous investigations. Sustainable yield can be estimated using a variety of
methods, with the most common method being a water-balance approach. This method compares
the amount of water that recharges into a basin (inflow) from a wide range of sources (natural and
anthropgenic) with the amount of water leaving the basin (outflow) from losses caused by pumping,
evapotranspiration, basin outflow etc. to estimate sustainable yield. The purpose of this study is to
assess the range of potential recharge to the SMB in order to assist the City with developing
strategies for adaptive management of its groundwater resources and facilitate future updates of the
SMB sustainable yield analysis.
The SMB is subdivided into five subbasins: Arcadia, Charnock, Olympic, Coastal, and Crestal; it has
an areal extent of approximately 50 square miles. Portions of several municipal jurisdictions lie within
the boundaries of the SMB, including the cities of Santa Monica, Beverly Hills, Culver City, Los
Angeles, and the County of Los Angeles. The City currently produces its groundwater supply from
the Arcadia, Olympic and Charnock subbasins. In early 2018, the City completed a new supply well
at a location at the Santa Monica Airport, within the Coastal subbasin. It is expected that this well
(Airport #1) will be placed into production by 2020. Additionally, there are future plans to drill up to
two additional supply wells in the Coastal subbasin. The SMB is non-adjudicated (no assigned
water rights); however, the City is currently the only entity withdrawing water for municipal delivery.
For fiscal year 2016-2017 the City pumped a total of approximately 10,190 AF of local groundwater.
1 Draft Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basins, Richard C.
Slade and Associates, July 2017
1 Ada Parkway, Suite 100, Irvine, CA 92618 USA +1.949.333.6600 +1.949.333.601 fax icf.com
Analysis
To develop refined estimates of sustainable yield it is imperative to understand the volume of water
entering the SMB via recharge. Several studies were reviewed and considered while conducting the
recharge analysis that is discussed in the following section. The sources include:
• Baseline Study to Evaluate the Value of Using Differential Interferometry Synthetic Aperture
Radar (DInSAR) to Monitor Land Elevation Changes Related to Groundwater Extractions
and Recharge for the Santa Monica Basin, Earth Consultants International, September 15,
2017.
• A 2017 map prepared by Earth Consultants International (ECI) which was generated by
LiDAR topography and computer- based Triangular Irregular Network Surface (TINS)
analysis showing a “flattened” surface area of a portion of the Santa Mountains that provides
recharge to the Santa Monica Basin.
• A 2018 ECI supplemental Differential Interferometer Synthetic Aperature Radar (DInSAR)
study of the basin that measured minute changes in seasonal basin surface topography due
to basin recharge and outflow.
• Estimating Spatially and Temporally Varying Recharge and Runoff from Precipitation and
Urban Irrigation in the Los Angeles Basin, California, Scientific Investigations Report 2016–
5068, U.S. Geological Survey, Joseph A. Hevesi and Tyler D. Johnson, 2016.
Estimating Recharge from Unpaved Areas and Public Open Space
Recharge occurs in the SMB from infiltration of precipitation, surface water runoff and urban-
related sources such as irrigation, storm drains and non-revenue water. Non-revenue water is
water that leaks from distribution pipelines and meters and is “lost” before it reaches the
customer. The accepted industry standard for non-revenue water is approximately 2-5% of the
total water volume placed into distribution. The volume placed into the distribution network is
referred to as “demand”. In fiscal year 2016- 2017 the demand volume for the City was
approximately 11,273 acre-feet (AF). This demand was met by a combination of of imported
water and local groundwater.
Sources of natural recharge are commonly known as spatially-distributed direct recharge. This
type of recharge is in addition to recharge that occurs at the northern margins of the SMB from
surface-water drainages, also known as mountain-front recharge. Within the SMB boundaries,
direct recharge from precipitation, mountain front runoff and irrigation occurs primarily in areas
that are pervious and unpaved, where water can directly infiltrate the underlying soil. Surface
water recharge from urban runoff is limited in the SMB because most of the larger streams and
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storm drain channels are either concrete-lined or diverted underground. Thus, most of the
direct recharge in the SMB is a result of infiltration from mountain front runoff and urban
irrigation.
To better quantify recharge in the Los Angeles Basin (which includes the SMB), the USGS
developed a computer model that simulates the amount of water that contributes to recharge
from precipitation, runoff and urban irrigation (USGS, 2016). The model also included all the
surface water drainages bordering the SMB that potentially contribute recharge. The USGS
model incorporated a new method for estimating recharge from residential and commercial
landscape irrigation based on land use and the percentage of pervious land area. The
computer model incorporated climate data from over 200 monitoring sites, including monthly
precipitation and maximum and minimum air temperatures. It also included data for land use
type, land cover, soil, vegetation and surficial geology. The model was calibrated to available
stream flow records.
Based on their research and the model results, the USGS concluded that urban irrigation is an
important component of overall spatially distributed recharge in the Los Angeles Basin
(including the SMB), contributing an average of 56 percent of the total recharge within the study
area. The USGS study noted that the amount of urban irrigation applied to landscaping across
the entire area of the Los Angeles basin can be large, exceeding natural rainfall in some places.
Studies have shown that more than 50 percent of the water used in a typical household is
applied as irrigation (USGS, 2016). Ideally, most of the water applied for irrigation would be
used by plants, but over-watering is very common because it is difficult for the average home
owner or business to estimate and adjust for the exact seasonal water demand. Therefore,
some of the irrigation water contributes to recharge and some becomes runoff. Urban irrigation
can also increase recharge from natural precipitation because of the wet antecedent soil
conditions caused by the irrigation. In the City there are polices to prevent runoff of irrigation
and these are strictly enforced.
The USGS model also estimated the amount of recharge as a function of unpaved area
(pervious areas) and percentage of plant-canopy cover (vegetation density). Impervious
surfaces (e.g. roadways, rooftops, parking lots) were estimated using the 2001 National Land
Cover Data (NLCD) which has a grid resolution of 30 meters. The average imperviousness for
the Los Angeles Basin area writ large was 33.7 percent. In the SMB, the percentage of
impervious area ranged from approximately 1 to 10 percent in the northern areas and in public
open spaces, to almost 100 percent in the more densely developed areas of Santa Monica and
Culver City (USGS, 2016). The model incorporated general soil type, soil thickness, land
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surface slope and aspect and other factors to arrive at an average annual recharge for the area
that includes the SMB.
The USGS estimated annual average direct recharge of 35 mm/year (1.4 inches/year) in the
Los Angeles Basin study area, which includes the SMB. (USGS, 2016). This represents about
10 percent of the annual precipitation rate and about 7 percent of the total combined inflow from
precipitation, surface-water inflow and urban irrigation. In low-lying urbanized areas, relatively
high recharge rates of more than 50 mm/year (approximately 2 inches/year) were estimated in
heavily irrigated areas with frequent inflows from upstream impervious areas. However, this
volume was found to vary significantly depending on the amount of unpaved and open area.
For most low-lying urbanized areas, the USGS estimated very low recharge (less than 1
mm/year). In the SMB, simulated recharge ranged from 20 – 50 mm/year in areas adjacent to
the Santa Monica Mountains and in some areas of Santa Monica and Culver City, presumably
based on identified public open spaces and the potential for irrigated residential areas (USGS,
2016). The model also indicated that a relatively large portion of the SMB has negligible
recharge because of dense development, with little or no pervious areas.
Estimating Recharge from Mountain Front Areas
Groundwater recharge entering the SMB from the canyons and streams flowing from the Santa
Monica Mountains, which border the basin to the north-northwest, is commonly referred to as
mountain-front recharge. Mountain-front recharge enters the SMB as lateral inflow of
groundwater directly into the subsurface (underflow) originating from surface-water drainages in
the Santa Monica Mountains. Unlike stream channels in the urbanized areas of the SMB, which
are mostly concrete-lined which can reduce the amount of inflow, the natural stream channels in
the Santa Monica Mountains allow runoff from precipitation to percolate directly into the
underlying sediments and ultimately recharge groundwater. This groundwater then flows
downgradient into and across the SMB.
The 2016 USGS recharge model incorporated mountain-front recharge in estimates of total
recharge for the SMB and other basins in the Los Angeles region. The USGS recharge
estimates for mountain-front recharge accounted for precipitation, air temperature, soil type and
thickness, root zone thickness, slope angle, slope aspect, vegetation type and degree of
imperviousness. The modeling indicated that mountain-front recharge contributes, on average,
approximately half as much water as direct recharge in the Los Angeles Basin. However, in the
SMB, mountain-front recharge forms a significant percentage of total recharge. The Santa
Monica Mountains had the highest 5-year average recharge for almost all the water years
simulated in the USGS model. The average potential mountain front recharge to the SMB from
Santa Monica Mountains Watershed Surface Area
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Explanation
Target Watershed
Calculated from DEM
Drainage Pattern
Calculated from DEM
Surface area cakulations:
Raster
317 Surface Area: 55327654 Sq.m
(13671.8 acres)
1 m TIN
3D Surface Area: 55272384 Sq.m
(13658.1 acres)
2D Surface Area: 49494936 Sq.m
(12230.4 acres)
All calculations were done
using Cartesian Coordinates.
Rase DEM: 2006 10-foot LIDAR
Digital Elevation Model (DEM)
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the Santa Monica Mountains was 82 mm/year (3.3 inches/year) compared to a total average
recharge of 116 mm/year when direct recharge is included (i.e. recharge from precipitation and
urban irrigation). Thus, mountain-front recharge represents about 71 percent of the average
total recharge entering the SMB. The USGS points out that mountain-front recharge is highly
variable depending on precipitation, with dry years resulting in much lower recharge to the SMB.
At the request of the City, Earth Consultants International (ECI), recently completed an analysis
of surface area in the watershed that drains to the SMB. ECI calculated the total surface area of
the watershed in three dimensions vs. a standard two-dimensional approach to account for the
steep slope angles in the Santa Monica Mountains. ECI’s analysis, which used triangular
irregular network surface (TINS) methods with a LiDAR dataset from 2006, indicated an
increase in surface area of approximately 12 percent when accounting for three-dimensional
topography. This higher surface area would generally correlate to greater recharge since there
is a larger surface area for water infiltration. This is in agreement with and seemingly validates
the relatively high percentage of recharge entering the SMB as mountain-front recharge
calculated by the USGS.
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Watershed 3-Dimensional Surface Area Calculated with TINS
In a separate study, the City commissioned ECI to conduct a Differential Interferometry
Synthetic Aperture Radar (DInSAR) study to assess whether historic pumping activities may
have caused wide spread sediment compaction in the various subbasins in the SMB (ECI,
September 15, 2017). Significant sediment compaction, caused by historic pumping of
groundwater, can reduce the amount of available groundwater in storage. When this condition
occurs, measurable subsidence of the surface topography can result. The ECI study determined
there was no evidence of significant wide-spread of basin sediment compaction or surface
subsidence due to the City’s historic localized groundwater pumping, with the possible
exception of some areas immediately around the City’s well fields located in the Arcadia and
Charnock subbasins, which was thought to have occurred historically when pumping was
greater and water levels were reportedly very low.
A review of the individual stacked interferometer images utilized for this study from the period
January 1, 2015 through November 27, 2016 identified a potential mechanism for recharging
the groundwater aquifers in the SMB that does not appear to have been previously identified
in the geologic literature.
In 2018 the City engaged ECI to conduct a supplemental DInSAR study focused on this
potential recharge phenomenon. Preliminary data from this new study strongly indicates that
under certain conditions a seasonal positive flux in regional topography centered on ancient
erosional pathways, such as abandoned river beds carved by the LA River, can be observed as
illustrated in the figure below. ECI believes that these events of topographic inflation may be
caused by recharge underflow into the SMB from nearby mountain front areas that lay outside
the boundaries of the SMB. The data show an area in the northeast corner of the basin that
seems to exhibit a positive topographic deflection caused by the transmission of groundwater in
shallow sediments that originate to the east of the Crestal subbasin in the Hollywood Basin, and
possibly extending down gradient to the Pacific Ocean. In the figure below blue colors indicate a
positive deflection (inflation) of topography above a measured baseline. Green colors are more
or less neutral, with yellow and warmer colors being representative of negative deflections
(deflation) from the baseline. This innovative information will be utilized in planned SMB
groundwater modeling work to be conducted in consultation between the City and the USGS.
,ICF
11/15/16 - 11/27/16
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Santa Monica Pier
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The area bounded in orange in the figure below shows the additional mountain-front area that is
external to the boundaries of the SMB that could be the source of additional recharge. This area
covers approximately 4 square miles of mountain-front.
According to the USGS recharge model, the average mountain-front recharge to the Hollywood
Basin was estimated to be 2,862 AF per year, with 100-year maximum and minimum recharge
estimates of 11,163 and 227 AF per year, respectively. Based on length of the mountain-front
boundary identified in the ECI study noted above, we estimate that approximately 25-35 percent
of this mountain-front recharge may be directed toward the SMB as underflow. This would
represent an average inflow of approximately 715 – 1000 AFY, with 100-year maximum and
minimum recharge estimates of approximately 2,791 and 57 AFY, respectively. This recharge
volume could potentially increase the overall average mountain-front water budget for the SMB.
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This recharge estimate is preliminary at this point and will be revisited based on the final ECI
analysis and hydrogeologic assessment.
Climate change has the potential to impact recharge in the SMB by affecting temperature and
precipitation rates in the region. Increased temperature could affect evapotranspiration rates,
while variations in precipitation (increases or decreases) would affect direct recharge. Urban
irrigation, which has been shown to be a significant source of direct recharge, would likely be
affected by climate change. A future decrease in recharge from precipitation may be offset by
an increase in urban irrigation unless abated by City conservation programs. Mountain-front
recharge, which is directly correlated to precipitation rates, would be most likely to be unaffected
by climate change for the immediate future as most climate general circulation models forecast
approximately the same volume of annual precipitation for the Santa Monica area for the next
several decades. One change in the precipitation cycle that is anticipated through 2030 is a shift
towards a majority of the annual precipitation in the SMB occurring later in the October to April
wet season, and it being associated with fewer, but more intense storms. Any decrease in
mountain-front recharge could significantly affect the rate of groundwater recharge in the SMB
and argues for and supports the City’s recent shift toward the innovative treatment and reuse of
non-conventional resources such as municipal waste water and brackish groundwater. To
assess the effects of climate change on its water resources, the City is in the process of
engaging a team of recognized climate change experts to develop a suite of possible climate
change scenarios that will be utilized to conduct biennial simulated climate change stress-tests
on the City’s sustainable yield analysis, conservation programs and planned water-related
capital improvement projects.
Findings and Conclusions
The amount of water entering the SMB as direct recharge and mountain-front recharge, as
described in the prior sections, constitute a significant portion of overall recharge entering the
basin. The 2016 USGS recharge study quantified these recharge components along with other
recharge inputs and outputs. The total average potential recharge for the SMB was estimated
from the USGS recharge model, as well as the maximum and minimum recharge for the basin
over the 100-year modeling period. These values are summarized in the following table.
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Summary of average inflows, outflows, and changes in storage for the Santa Monica Groundwater Basin
USGS Los Angeles Basin Watershed Model
Inflows Outflows
Potential
ET Precip.
Surface
Water
Urban
Irrigation Runoff ET
Direct
Recharge
Surface
Water
Change
in
Storage
Potential
Mountain-
Front
Recharge
Total
Potential
Recharge
Average 119,692 35,501 6,405 14,568 12,582 34,382 3,259 18,978 -154 7,953 11,212
Max 127,004 83,859 -- 14,601 30,288 43,948 15,501 30,288 14,374 26,404 41,913
Min 109,566 7,775 -- 14,601 2,546 23,843 259 2,546 -9,599 462 1,167
All values reported in acre-feet per year
The inflow and outflow estimates shown above indicate that a substantial portion of average
annual recharge to the SMB results from mountain front recharge, with direct recharge
representing a smaller overall contribution. The 100-year average of total potential recharge in
the SMB is 11,212 AFY, with maximum and minimum recharge values of 41,913 AY and 1,167
AFY, respectively. The addition of an average volume of recharge from non-revenue water
ranging from 204 AFY to 510 AFY (representing approximately 2-5 % of average water
demand) may increase the range of average total potential recharge to between 11,416 AFY
and 11, 722 AFY.
When the estimated underflow from areas identified by the preliminary DInSAR study are
included, the 100-year average potential recharge for the SMB is approximately 12,131 to
12,722 AFY, with 100-year maximum and minimum recharge values of 44,704 to 1,224 AF/Y,
respectively.
The City is in the process of permitting a new well for aquifer recharge as art of its Sustainable
Water Infrastructure Project (SWIP). When operational, this well will be capable of artificially
recharging the City’s aquifers with approximately another 1,000 AFY of highly treated water
derived from non-conventional resources such as stormwater, brackish groundwater and
municipal waste water, thereby increasing the total range of recharge to between approximately
13,131 AFY to 13,722 AFY. In addition, the City is engaging ECI to conduct a supplemental
TINS analysis of the additional mountain front area that is thought to be contributing to recharge
from outside the SMB. Results from this analysis are expected to increase the estimated range
of potential recharge from this area.
Long-term the City is exploring new conservation programs to reduce demand and innovative
projects for the expanded treatment and reuse of non-conventional water resources such as
brackish/saline groundwater. When integrated with the recently completed Clean Beaches
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Initiative Project (CBI) and the City’s SWIP, these programs and projects will result in a
cohesive and comprehensive strategy for adaptive management of the City’s water resources.
Lastly, it should be noted that this recharge estimate does not account for underflow to or from
adjacent groundwater basins (other than the noted potential underflow from the Hollywood
Basin into the Santa Monica Basin), nor does it consider the effects of groundwater extraction
from pumping wells. However, it provides a valuable preliminary estimate of potential recharge
in the SMB that is useful for the evaluation and estimation of sustainable yield. We understand
that the City intends to revisit and update its recharge and sustainable yield estimates utilizing a
water balance method that is consistent with hydrogeologic modeling concepts every two years
going forward. This practice will help ensure the City meets and maintains its objectives of water
resiliency and self-sufficiency.