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SR 01-09-2018 9A City Council Report City Council Meeting: January 9, 2018 Agenda Item: 9.A 1 of 28 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 2 of 28 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 3 of 28 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: 4 of 28 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 5 of 28  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 6 of 28 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. 7 of 28 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: 8 of 28 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): 9 of 28  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 10 of 28 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 11 of 28 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. 12 of 28 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% 13 of 28 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 14 of 28 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 15 of 28 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. 16 of 28 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. 17 of 28 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. 18 of 28 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 19 of 28 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. 22 of 28 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: 24 of 28  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. 25 of 28 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 $11,100,000. Prepared By: Gil Borboa, Water Resources Manager Approved Forwarded to Council Attachments: A. February 24, 2015 Staff Report - Public Hearing to Adopt Water Rates B. February 23, 2016 Staff Report - State of the Water Fund C. November 22, 2016 Staff Report - State of the Water Fund D. 2018 Proposed Water Rates E. Water Fund Balance Projections - Two Rate Adjustment Options F. Santa Monica Basin Preliminary Sustainable Yield Analysis - July 2017 28 of 28 G. July 11, 2017 Staff Report - Award Contract for Three Coastal Subbasin Exploratory Borings/Wells and Replacement of Well SM-7 H. Santa Monica Basin DInSAR Report - September 2017 I. June 27, 2017 Staff Report - Award Construction Contract for Clean Beaches Project J. September 12, 2017 Staff Report - Authorizations for SWIP Funding and Owner's Engineer Agreements K. December 19, 2017 Information Item - Update on Water Mediation Settlement Funds L. Written Comments M. Powerpoint Presentation Tier Full Suspension / 0% Adjustment (per HCF) Partial Suspension +5% Adjustment (per HCF) Usage Range  per Billing Period (HCF's) Tier 13 . 0 1$                           3.16$                              0 to 14 Tier 24 . 5 0$                           4.73$                              15 to 40 Tier 36 . 7 6$                           7.10$                              41 to 148 Tier 4 10.57$                         11.10$                            149+ Tier 13 . 0 1$                           3.16$                              0 to 4 per dwelling unit Tier 24 . 5 0$                           4.73$                              5 to 9 per dwelling unit Tier 36 . 7 6$                           7.10$                              10 to 20 per dwelling unit Tier 4 10.57$                         11.10$                            21+ per dwelling unit Tier 14 . 2 7$                           4.48$                              Depends on meter size* Tier 2 10.53$                         11.06$                            Depends on meter size* Recycled Water 3.84$                           4.03$                              All usage Meter Size Full Suspension Fixed Charge  per Billing Period Partial Suspension +5% Adjustment Fixed Charge 1‐1/2" meter 43.05$                         45.20$                             2" meter 69.07$                         72.52$                             3" meter 118.87$                      124.81$                           4" meter 189.99$                      199.49$                           6" meter 367.71$                      386.10$                           8" meter 580.99$                      610.04$                           10" meter 829.80$                      871.29$                           *Non‐Residential Accounts ‐  Tier Designations by Meter Size and Usage Range Meter Size  Tier 1 Usage (HCF's) Tier 2 Usage (HCF's) 3/4" meter 0 to 210 211+ 1" meter 0 to 210 211+ 1‐1/2" meter 0 to 465 466+ 2" meter 0 to 870 871+ 3" meter 0 to 1,700 1,701+ 4" meter 0 to 2,550 2,551+ 6"+ meter 0 to 5,280 5,281+ ATTACHMENT D Each billing period is approximately 61 days (~6 billing periods per year) Fireline Service Rates 2018 Water Rate Options by Account Type, Tier and Meter Size Single Family Accounts Multi‐Family Accounts Non‐Residential Accounts 1 HCF = 1 Hundred Cubic Feet of water = 748 gallons Wa t e r F u n d - 2 5 FY 2 0 1 7 - 1 8 t o F Y 2 0 2 1 - 2 2 FY 2 0 1 7 - 1 8 F Y 2 0 1 8 - 1 9 F Y 2 0 1 9 - 2 0 F Y 2 0 2 0 - 2 1 F Y 2 0 2 1 - 2 2 BE G I N N I N G F U N D B A L A N C E 3 6 , 7 2 7 , 4 2 3 1 8 , 4 7 1 , 4 3 8 1 4 , 5 0 3 , 0 2 6 7 , 9 9 7 , 2 2 7 7 , 1 2 0 , 3 8 2 Re v e n u e s 2 5 , 6 6 8 , 1 0 6 2 7 , 5 7 1 , 1 0 1 2 8 , 6 0 4 , 1 5 0 2 8 , 8 7 0 , 8 7 6 2 9 , 1 4 0 , 3 9 0 Ex p e n d i t u r e s ( 2 4 , 2 2 8 , 2 5 0 ) ( 2 3 , 2 6 8 , 9 2 3 ) ( 2 3 , 7 7 1 , 1 8 1 ) ( 2 2 , 1 7 3 , 0 6 4 ) ( 2 1 , 6 5 9 , 6 6 3 ) Sa l a r i e s a n d W a g e s ( 6 , 2 2 8 , 6 8 3 ) ( 6 , 4 8 4 , 3 3 8 ) ( 6 , 8 1 2 , 7 3 9 ) ( 7 , 1 5 0 , 4 7 7 ) ( 7 , 3 9 7 , 6 1 6 ) Su p p l i e s a n d E x p e n s e s ( 1 7 , 9 9 9 , 5 6 7 ) ( 1 6 , 7 8 4 , 5 8 5 ) ( 1 6 , 9 5 8 , 4 4 3 ) ( 1 5 , 0 2 2 , 5 8 7 ) ( 1 4 , 2 6 2 , 0 4 7 ) No n - D e p t . T r a n s a c t i o n s ( 4 , 1 8 5 , 6 7 7 ) ( 2 , 1 3 7 , 7 3 5 ) ( 2 , 1 9 8 , 2 0 9 ) ( 2 , 2 6 1 , 8 4 5 ) ( 2 , 3 2 3 , 1 8 1 ) Ca p i t a l I m p r o v e m e n t P r o g r a m ( C I P ) ( 1 5 , 5 1 0 , 1 6 3 ) ( 6 , 1 3 2 , 8 5 5 ) ( 9 , 1 4 0 , 5 5 9 ) ( 5 , 3 1 2 , 8 1 2 ) ( 5 , 2 7 7 , 5 8 3 ) Co n s t r u c t i o n P r o j e c t s ( 5 9 2 , 3 2 3 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) Fa c i l i t i e s & I n f r a s t r u c t u r e ( 7 , 3 2 5 , 9 7 3 ) ( 8 4 2 , 0 6 7 ) ( 3 , 8 7 9 , 7 7 1 ) ( 4 2 2 , 0 2 4 ) ( 4 3 6 , 7 9 5 ) Su s t a i n a b i l i t y & C o n s e r v a t i o n ( 5 8 9 , 0 9 8 ) ( 3 0 0 , 0 0 0 ) ( 1 7 0 , 0 0 0 ) ( 1 0 0 , 0 0 0 ) ( 1 0 0 , 0 0 0 ) Sy s t e m s & T e c h n o l o g y ( 4 5 6 , 6 1 0 ) ( 3 4 0 , 7 8 8 ) ( 4 4 0 , 7 8 8 ) ( 1 4 0 , 7 8 8 ) ( 9 0 , 7 8 8 ) Wa t e r M a i n R e p l a c e m e n t s ( 5 , 5 4 6 , 1 5 9 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) Pr o p o s e d N e w C I P - R e s e r v o i r I m p r o v e m e n t s ( 9 0 0 , 0 0 0 ) Pr o p o s e d N e w C I P - C i t y / U S G S N u m e r i c a l F l o w M o d e l ( 3 0 0 , 0 0 0 ) Pr o p o s e d N e w C I P - A r c a d i a E f f i c i e n c y U p g r a d e P i l o t ( 2 5 0 , 0 0 0 ) Pr o p o s e d N e w C I P - S u p p l e m e n t a l D I n S A R S t u d y ( 1 0 0 , 0 0 0 ) Pr o p o s e d C I P A d d - G r o u n d w a t e r S u s t a i n a b i l i t y P l a n ( 1 5 0 , 0 0 0 ) Pr o p o s e d C I P R e d u c t i o n - A r c a d i a M e m b r a n e s 7 0 0 , 0 0 0 PR O J E C T E D E N D I N G F U N D B A L A N C E 18 , 4 7 1 , 4 3 8 1 4 , 5 0 3 , 0 2 6 7 , 9 9 7 , 2 2 7 7 , 1 2 0 , 3 8 2 7 , 0 0 0 , 3 4 5 MI N I M U M E S T A B L I S H E D C O U N C I L R E S E R V E -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7,000,000 VA R I A N C E 11 , 4 7 1 , 4 3 8 7 , 5 0 3 , 0 2 6 9 9 7 , 2 2 7 1 2 0 , 3 8 2 3 4 5 OP T I O N 1 ( R E C O M M E N D E D ) - 5 % I N C R E A S E F O R 2 0 1 8 - P A R T I A L S U S P E N S I O N O F 9 % I N C R E A S E AT T A C H M E N T E - W A T E R F U N D 5 - Y E A R F O R E C A S T FI N A N C I A L S T A T U S U P D A T E Wa t e r F u n d - 2 5 FY 2 0 1 7 - 1 8 t o F Y 2 0 2 1 - 2 2 FY 2 0 1 7 - 1 8 F Y 2 0 1 8 - 1 9 F Y 2 0 1 9 - 2 0 F Y 2 0 2 0 - 2 1 F Y 2 0 2 1 - 2 2 BE G I N N I N G F U N D B A L A N C E 3 6 , 7 2 7 , 4 2 3 1 7 , 9 8 3 , 3 3 6 1 2 , 8 4 3 , 7 9 7 5 , 1 0 9 , 3 5 3 2 , 9 9 1 , 5 7 6 Re v e n u e s 2 5 , 1 8 0 , 0 0 4 2 6 , 3 9 9 , 9 7 4 2 7 , 3 7 5 , 5 0 5 2 7 , 6 2 9 , 9 4 4 2 7 , 8 8 7 , 0 4 9 Ex p e n d i t u r e s ( 2 4 , 2 2 8 , 2 5 0 ) ( 2 3 , 2 6 8 , 9 2 3 ) ( 2 3 , 7 7 1 , 1 8 1 ) ( 2 2 , 1 7 3 , 0 6 4 ) ( 2 1 , 6 5 9 , 6 6 3 ) Sa l a r i e s a n d W a g e s ( 6 , 2 2 8 , 6 8 3 ) ( 6 , 4 8 4 , 3 3 8 ) ( 6 , 8 1 2 , 7 3 9 ) ( 7 , 1 5 0 , 4 7 7 ) ( 7 , 3 9 7 , 6 1 6 ) Su p p l i e s a n d E x p e n s e s ( 1 7 , 9 9 9 , 5 6 7 ) ( 1 6 , 7 8 4 , 5 8 5 ) ( 1 6 , 9 5 8 , 4 4 3 ) ( 1 5 , 0 2 2 , 5 8 7 ) ( 1 4 , 2 6 2 , 0 4 7 ) No n - D e p t . T r a n s a c t i o n s ( 4 , 1 8 5 , 6 7 7 ) ( 2 , 1 3 7 , 7 3 5 ) ( 2 , 1 9 8 , 2 0 9 ) ( 2 , 2 6 1 , 8 4 5 ) ( 2 , 3 2 3 , 1 8 1 ) Ca p i t a l I m p r o v e m e n t P r o g r a m ( C I P ) ( 1 5 , 5 1 0 , 1 6 3 ) ( 6 , 1 3 2 , 8 5 5 ) ( 9 , 1 4 0 , 5 5 9 ) ( 5 , 3 1 2 , 8 1 2 ) ( 5 , 2 7 7 , 5 8 3 ) Co n s t r u c t i o n P r o j e c t s ( 5 9 2 , 3 2 3 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) ( 3 0 0 , 0 0 0 ) Fa c i l i t i e s & I n f r a s t r u c t u r e ( 7 , 3 2 5 , 9 7 3 ) ( 8 4 2 , 0 6 7 ) ( 3 , 8 7 9 , 7 7 1 ) ( 4 2 2 , 0 2 4 ) ( 4 3 6 , 7 9 5 ) Su s t a i n a b i l i t y & C o n s e r v a t i o n ( 5 8 9 , 0 9 8 ) ( 3 0 0 , 0 0 0 ) ( 1 7 0 , 0 0 0 ) ( 1 0 0 , 0 0 0 ) ( 1 0 0 , 0 0 0 ) Sy s t e m s & T e c h n o l o g y ( 4 5 6 , 6 1 0 ) ( 3 4 0 , 7 8 8 ) ( 4 4 0 , 7 8 8 ) ( 1 4 0 , 7 8 8 ) ( 9 0 , 7 8 8 ) Wa t e r M a i n R e p l a c e m e n t s ( 5 , 5 4 6 , 1 5 9 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) ( 4 , 3 5 0 , 0 0 0 ) Pr o p o s e d N e w C I P - R e s e r v o i r I m p r o v e m e n t s ( 9 0 0 , 0 0 0 ) Pr o p o s e d N e w C I P - C i t y / U S G S N u m e r i c a l F l o w M o d e l ( 3 0 0 , 0 0 0 ) Pr o p o s e d N e w C I P - A r c a d i a E f f i c i e n c y U p g r a d e P i l o t ( 2 5 0 , 0 0 0 ) Pr o p o s e d N e w C I P - S u p p l e m e n t a l D I n S A R S t u d y ( 1 0 0 , 0 0 0 ) Pr o p o s e d C I P A d d - G r o u n d w a t e r S u s t a i n a b i l i t y P l a n ( 1 5 0 , 0 0 0 ) Pr o p o s e d C I P R e d u c t i o n - A r c a d i a M e m b r a n e s 7 0 0 , 0 0 0 PR O J E C T E D E N D I N G F U N D B A L A N C E 17 , 9 8 3 , 3 3 6 1 2 , 8 4 3 , 7 9 7 5 , 1 0 9 , 3 5 3 2 , 9 9 1 , 5 7 6 1 , 6 1 8 , 1 9 9 MI N I M U M E S T A B L I S H E D C O U N C I L R E S E R V E -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7 , 0 0 0 , 0 0 0 -7,000,000 VA R I A N C E 10 , 9 8 3 , 3 3 6 5 , 8 4 3 , 7 9 7 (1 , 8 9 0 , 6 4 7 ) ( 4 , 0 0 8 , 4 2 4 ) ( 5 , 3 8 1 , 8 0 1 ) OP T I O N 2 - 0 % I N C R E A S E F O R 2 0 1 8 - F U L L S U S P E N S I O N O F 9 % I N C R E A S E AT T A C H M E N T E - W A T E R F U N D 5 - Y E A R F O R E C A S T FI N A N C I A L S T A T U S U P D A T E 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 PRELIMINARY STUDY OF THE SUSTAINABLE YIELD OF THE SANTA MONICA GROUNDWATER SUBBASINS 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 July 2017 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 PRELIMINARY STUDY OF THE SUSTAINABLE YIELD OF THE SANTA MONICA GROUNDWATER SUBBASINS 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 July 2017 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  INTRODUCTION ..................................................................................................................... 1  SUSTAINABLE YIELD ........................................................................................................... 1  INTRODUCTION .......................................................................................................................... 4  BACKGROUND ...................................................................................................................... 4  SUSTAINABLE GROUNDWATER MANAGEMENT ............................................................. 4  SUMMARY OF “PERENNIAL YIELD,” “SAFE YIELD,” & “SUSTAINABILITY” TERMS ... 7  PREVIOUS SUSTAINABLE YIELD VALUES ........................................................................ 8  CALCULATION OF SUSTAINABLE YIELD .......................................................................... 9  Introduction ....................................................................................................................... 9  Summary of Methods for Calculating Sustainable Yield ................................................. 12  FINDINGS 15  GROUNDWATER BASIN AND SUBBASIN BOUNDARIES ............................................... 15  GENERAL GEOLOGIC/HYDROGEOLOGIC CONDITIONS ............................................... 16  Water-Bearing Sediments ............................................................................................... 17  Recent (Holocene) Alluvium ................................................................................ 17  Lakewood Formation ........................................................................................... 17  San Pedro Formation .......................................................................................... 18  Nonwater-Bearing Rocks ................................................................................................ 19  Geologic Structures ........................................................................................................ 20  WATERSHED AREA ............................................................................................................ 21  NATURAL RECHARGE ....................................................................................................... 22  ARTIFICIAL RECHARGE ..................................................................................................... 24  HYDROLOGIC BASELINE CONDITIONS ........................................................................... 25  Rainfall Totals ................................................................................................................. 25  Accumulated Departure of Rainfall ................................................................................. 26  Selection of Baseline Hydrologic Conditions ................................................................... 26  GROUNDWATER EXTRACTIONS ...................................................................................... 28  Extractions by City .......................................................................................................... 28   Extractions by Others ...................................................................................................... 29  WATER LEVELS .................................................................................................................. 30  Water Level Hydrographs ............................................................................................... 30  Water Level Hydrographs – “Key” Well Concept ............................................................ 33  Arcadia Subbasin Key Well Hydrographs............................................................ 33  Charnock Subbasin Key Well Hydrograph .......................................................... 34  Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Subbasins Santa Monica Groundwater Basin iv Olympic Subbasin Key Well Hydrograph ............................................................. 35  Coastal Subbasin Key Well Hydrographs............................................................ 36  Crestal Subbasin Key Well Hydrograph .............................................................. 36  GROUNDWATER IN STORAGE .......................................................................................... 37  Storage Subunits and Parameters .................................................................................. 37  Calculation of Groundwater in Storage ........................................................................... 38  SUBUNIT/SUBBASIN CHANGES IN GROUNDWATER IN STORAGE CALCULATIONS 39   Method 1: Change in Groundwater Storage for the Entire Hydrologic Baseline Period . 39  Arcadia Groundwater Storage Subunit/Subbasin ................................................ 39  Charnock Groundwater Storage Subunit............................................................. 41  Olympic Groundwater Storage Subunit ............................................................... 41  Method 2: Change in Groundwater Storage for a Split Hydrologic Baseline Period ...... 42  Arcadia Groundwater Storage Subunit/Subbasin ................................................ 42  Charnock Groundwater Storage Subunit/Subbasin ............................................. 43  Change in Groundwater Storage for the Coastal Subbasin ............................................ 44  PRELIMINARY CALCULATIONS OF SUSTAINABLE (PERENNIAL) YIELDS ................. 44  DISCUSSION OF HISTORICAL VALUES BY OTHERS ..................................................... 45  Comparison of Sustainable Yield Values ........................................................................ 45  Arcadia Subbasin ............................................................................................................ 46  Charnock Subbasin ......................................................................................................... 47  Olympic Subbasin ........................................................................................................... 49  Coastal Subbasin ............................................................................................................ 49  Crestal Subbasin ............................................................................................................. 49   CONCLUSIONS & RECOMMENDATIONS ............................................................................... 50  REFERENCES REVIEWED ....................................................................................................... 52  APPENDIX I - 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 Figure 10B - Charnock Wellfield/Subbasin Hydrographs Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Subbasins Santa Monica Groundwater Basin v 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 No. 16, 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 Figure 13A - Key Well Hydrograph, Santa Monica Well No. 5, Arcadia Subbasin, Split Change in Storage Figure 13B - Key Well Hydrograph, Charnock Well No. 16, Charnock Subbasin, Split Change in Storage APPENDIX II – TABLES Table 1 - Summary of Well Construction Data for Existing City-Owned Wells Table 2 - Groundwater Production Totals by City Wellfields and Others (1988 through 2016) Table 3A - Preliminary Calculations of Change in Groundwater in Storage During Baseline Period for the Arcadia, Charnock and Olympic Groundwater Subbasins (Method 1 Calculations) Table 3B - Preliminary Calculations of Change in Groundwater in Storage During Split Baseline Period for the Arcadia, Charnock and Olympic Groundwater Subbasins (Method 2 Calculations) Table 4A - Preliminary Calculations of Sustainable Yield, Santa Monica Subbasins (Method 1 Calculations) Table 4B - Preliminary Calculations of Sustainable Yield, Santa Monica Subbasins (Method 2 Calculations) Table 5 - Comparison of Sustainable Yield Values, Santa Monica Subbasins Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Subbasins Santa Monica Groundwater 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 AFY acre feet per year b equation variable for saturated aquifer thickness BCC Brentwood Country Club brp below reference point bgs below ground surface DWR California Department of Water Resources GRA Groundwater Resources Association GSP Groundwater Sustainability Plan KJC Kennedy/Jenks Consultants 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 SCWC Southern California Water Company (now Golden State Water Company) SGMA Sustainable Groundwater Management Act SMGB Santa Monica Groundwater Basin SMURRF Santa Monica Urban Runoff Recycling Facility SWL(s) Static water level(s) ULARA Upper Los Angeles River Area WCB West Coast Groundwater Basin WRCC Western Regional Climate Center Measurements/Units Abbreviations gpm gallons per minute gpm/ft ddn gpm per foot of drawdown mg/L milligrams per Liter sq mi square miles µg/L micrograms per Liter 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 conduct an assessment of the sustainable yield of the various subbasins within the Santa Monica Groundwater Basin (SMGB). These groundwater subbasins include the Arcadia, Charnock, Coastal, Crestal, and Olympic subbasins. Of the five subbasins, the City currently only pumps groundwater from the Arcadia, Charnock and Olympic subbasins. The City is in the process of collecting data in order to evaluate the quantity and quality of groundwater that may be available within that portion of the Coastal subbasin that lies beneath the City. Future exploration of the Crestal subbasin will be done in conjunction with ongoing Sustainable Groundwater Management Act (SGMA) activities being conducted in cooperation with the neighboring municipalities of Beverly Hills, Los Angeles and Culver City. This report is considered to be a “living document” and as such will be updated and revised as new data becomes available or well field conditions warrant. Details specific to the methods of analysis and SMGB hydrogeology are provided within the main body of the report text. 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 extraction 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 extractions 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. Because the City did not pump for a number of 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 storage for the 29-year baseline period. In an attempt to overcome this complexity, two methods of calculation for the change in aquifer storage (ΔS) were employed: Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 2 o Method 1: Calculating ΔS over the entire 29-year period for the three subbasins in which the City has active wells. o Method 2: Calculating ΔS over a split baseline period in the Arcadia and Charnock subbasins because of the years of no plumage in these two subbasins. City wells in the Olympic Subbasin were continuously pumped over the entire baseline period and, thus, there was no need to split the baseline period for this subbasin. Average subbasin extractions over the 29 year baseline period utilizing the two methods described above are: o Arcadia subbasin: 365 - 424 AFY. (shutdown in 4 out of 29 years) o Charnock subbasin: 3,250 - 5,900 AFY (shutdown in 13 out of 29 years) o Olympic subbasin:1900 AFY (no shutdown during baseline period) Third party extractions, primarily from two golf courses, have also occurred in the Arcadia subbasin. When these withdrawals are included the extractions for that subbasin are estimated be on the order of 1,000 AFY. Average withdrawals from the Charnock and Olympic subbasins between 2011 and 2016 have been around 9,757 and 2,017 AFY, respectively. Based on the total amounts extracted from the three aforementioned subbasins, and on the above two methods for calculating the change in groundwater storage, RCS was able to calculate estimated ranges of the sustainable yield of each active groundwater subbasins in the SMGB., Values from the previous studies by others were compiled by RCS for the City as part of a prior RCS evaluation of several reports from various sources. The following table lists the current and previous estimates of sustainable yield values for those portions of the subbasins currently subject to pumping by the City. GROUNDWATER SUBBASIN CURRENTLY CALCULATED SUSTAINABLE YIELD (AFY) PREVIOUSLY CALCULATED SUSTAINABLE YIELD (AFY) Arcadia 600 to 800 2000 Charnock 4,600 to 5,900 4,420 to 8,200 Olympic 1,600 to 1,700 3,275 TOTALS: 6,800 to 8,400 9,695 to 13,475 Coastal Yet To Be Determined 4,225 Crestal Yet To Be Determined 2,000 The limitations on possible future groundwater withdrawals from the three active subbasins presented by the estimated sustainable yields indicate that the City’s approach of investigating additional water supply in the Coastal subbasin and the pursuit of indirect potable reuse from its planned Sustainable Water Infrastructure Project (SWIP) are prudent and necessary for the City to achieve its long-term objective of independence from environmentally costly imported water. Chief among these 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 Costal subbasin will help alleviate the current heavy reliance on the three subbasins currently providing groundwater supply and could facilitate the Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 3 implementation of adaptive pumping measures where individual wells or well fields 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 stormwater runoff, brackish/saline groundwater and municipal wastewater. The City is in the process of beginning construction of its Clean Beaches Project which will install a below grade 1.6 million gallon stormwater harvest tank north of the Santa Monica Pier. This innovative project will harvest 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, for indirect potable reuse via aquifer recharge. The Clean Beaches Project is scheduled for completion in 2018. Awaiting funding in 2017 is the City’s Sustainable Water Infrastructure Project (SWIP). The SWIP is comprised of three integrated elements that once constructed will produce approximately 1,120 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 continue to explore the distributed water strategy (i.e. stand alone, small scale treatment facilities) demonstrated by the Clean Beaches Project, SMURRF and the SWIP in order to increase conjunctive reuse of all water resources, and especially non- conventional resources, available to the City. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 4 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; this basin underlies and extends beyond the entire City limits of Santa Monica. Currently, the City’s water system serves a population of 93,834 via 17,847 connections within a service area of 8.3 square miles. As a charter member of the Metropolitan Water District of Southern California (MWD), the City is currently purchasing and importing water to augment its local supply. For the long term, the City is committed to eliminating its dependence on this 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 possibly available non-conventional water resources, such as brackish groundwater, dry weather and stormwater 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 (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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 5 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). In particular, 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 extractions, 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 with regard to 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. 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 6 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 with regard to 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 with regard to declines of water levels in many groundwater basins in the State. According to the DWR, factors leading to declines in water levels include: o “Chronic long-term pumping of groundwater in excess of 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 “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”. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 7 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, with regard to impacts of pumpage on groundwater in the subbasins within the SMGB. The main 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. SUMMARY OF “PERENNIAL YIELD,” “SAFE YIELD,” & “SUSTAINABILITY” TERMS Several estimates of the “safe yield” or “perennial yield” of the individual subbasins within the SMGB have been historically generated for the City by prior investigators. However, because of a paucity of data, reliable or accurate values for each subbasin have not been established. Consequently, 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 courts. 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 8 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 to be a dynamic value, which can change under varying conditions of groundwater extractions 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, prepared by RCS for Kennedy Jenks Consultants (KJC) and the City (dated March 27, 2013), an initial review was performed of historic reports that had presented sustainable yield values for the subbasins within the SMGB. That 2013-dated RCS document was able to be used 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 by others for each 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 9 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, and the movement, flows and quantities of groundwater are governed by the equation: Inflow-Outflow = Change in Storage (ΔS). In particular, the hydrologic water balance equation is controlled by several variables, as shown in the following equation: Surface water recharge (via percolation of rainfall and streamflows 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; 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 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 components of the classical 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 10 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, extractions, 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. 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 11 However, Bredehoeft et al (1982) noted that there is a common misconception among water resources managers with regard to 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 mathematical basis. Indeed, they stated (1982, p. 55) that: “Although knowledge of the virgin rates of recharge and discharge is interesting, such knowledge is almost irrelevant in determining the sustained yield of a particular groundwater reservoir.” 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 = Δ V / ( Sy*A) Where: S = the basin-wide average drawdown. Δ V = t h e v o l u m e r e m o v e d f r o m s t o rage (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 Bredehoeft, et al (1982) concluded their re-examination with three important items: 1. The magnitude of development (of the water resources) depends on hydrologic effects that a water manager may desire to tolerate. To calculate this, the boundaries and hydraulic properties of the aquifer system(s) should be known. Further, they stated (1982) that “natural recharge and discharge at no time enter these calculations. Hence a water budget is of little use in determining the magnitude of development.” 2. “The magnitude of sustained groundwater pumpage generally depends on how much of the natural discharge can be captured.” 3. “Steady state is achieved only when pumping is balanced by capture. In most cases the change in recharge is small or zero and balance must be achieved by a change in discharge. Before any natural discharge can be captured, some water must be removed from storage by pumping. In many circumstances the dynamics of the groundwater system are such that long periods of time are necessary before any kind of an equilibrium condition can develop. In some circumstances the system response is so slow that mining will continue well beyond any reasonable planning.” Moreover, with regard to conducting a water balance of the SMGB, historic and current data for each of the items listed above on pages 12 and 13 are lacking for the subbasins of the SMGB, and, thus, a more practical approach is needed to evaluate the sustainable yields of those subbasins for this current study. Accordingly, the results of this study would represent the amount of groundwater that can be pumped from the aquifer system(s) without causing a Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 12 negative impact to the subbasin, such as “overdraft,” where water levels would tend to show a continued (and/or progressive) decline over long periods of time when subbasin pumping has occurred over a significantly long period as well. Other potentially negative impacts from long- term pumping in SGMB in excess of the sustainable yield could include: lowering of water levels beyond the bowl setting (pump intake) of existing City wells; permanent lowering of water levels to depths that lie below the depth to the uppermost perforations in some/all City wells; introduction of poor quality waters from surrounding materials (e.g., the upwelling of brackish water from marine-deposited sedimentary rocks that directly underlie the local groundwater basin); seawater intrusion from the west; and land subsidence. In this current 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. 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 for the Maximum Contaminant Levels (MCLs) that exist for certain constituents in the pumped groundwater. Also not addressed in this report are: water rights, because pumping rights in the SMGB have not been adjudicated by the courts; and potential land subsidence caused by historic or future pumping, because this issue is not within the expertise of RCS (such an evaluation would require specialists in geotechnical engineering, etc.). The City has commissioned a separate satellite-based interferometer synthetic aperture radar (InSAR) study to assess various subbasin characteristics, including subsidence. The InSAR study results will be included in a planned updated revision to this RCS report in Fall 2017. Summary of Methods for Calculating Sustainable Yield As stated above, the "classical" method of evaluating the sustainable yield of a groundwater basin involves solving the hydrologic water balance equation. This “classical” solution requires the collection and/or availability of extensive data on all aspects of surface water and groundwater in each groundwater subbasin within the SMGB. However, there is another more conventional, less intensive and more practical method for estimating the sustainable yield of an aquifer system(s) or groundwater basin, wherever and whenever the database for many of the standard data elements are lacking (such as runoff data). This method, which has been Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 13 discussed by various investigators, including Farvolden (1967), Bredehoeft (1982), and RCS (1986), is commonly known as the pumping and change-in-storage method. 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. 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 of those materials. Also, areas of confined and unconfined groundwater conditions must be delineated. 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 groundwater in storage change values can be derived. The selected baseline period should not be preceded by a hydrologically high rainfall period in order to avoid so-called water-in-transit problems. Following selection of a representative rainfall baseline period, the volume of pumped groundwater during that period is totaled and an average annual pumpage volume is calculated. The net change of groundwater in storage occurring between the be- ginning 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 w h e r e: S = the storativity SS = the specific storage b = t h e a q u i f e r t h i c k n e s s . Sy = the specific yield (that amount of water yielded only b y 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 (the water that can be provided to a well by gravity drainage). However, for confined aquifers the storativity can actually 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 in storage, due to lowering the amount of head in an aquifer. Thus, the change-in-storage method is directly Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 14 applicable to unconfined aquifer systems, but the method may only provide approximate results for a confined aquifer system. In essence, confined systems tend to deliver greater amounts of water than unconfined systems, initially. The pumpage and change-in-storage method is considered to be a suitable and appropriate method for determining the sustainable yield of the subject subbasins, because the City has sufficient data on SWLs and extraction volumes from each of its wells, and estimates can be made for the known private-party pumping in 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 Annual groundwater extractions, obtained directly from City records and from estimates of pumpage by others. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 15 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. 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 within the SMGB identified in that MWD study. 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 describe 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 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). At this time, the City has 16 existing municipal-supply water wells, and 11 of these are being pumped on an active basis to help meet the current water demand of its residents and customers. Figure 3B, “Map of City Well Locations,” shows the locations and names of existing City wells and also of key Los Angeles County Flood Control District (LACFCD) groundwater monitoring wells in the SMGB. Three of these wells are used as water level observation wells Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 16 by the City. In addition, the City has one shallow water level observation well located in Marine Park in the southern portion of the City. Table 1, “Summary of Well Construction Data for City- Owned Wells”, in Appendix 2, provides the construction data available for each existing City water-supply well. 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. 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. 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 nonwater-bearing rocks group which underlies the water-bearing sediments and which are comprised by geologically old, lithified, or Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 17 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 considered to be 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 considered to be 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), whereas 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 Santa Monica Basin. Thus, these strata were either never Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 18 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 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 a large number of 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 subsequent to 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 when the well is pumped (i.e., such a well is known as a “sander”). Many old, former wells owned by the City were drilled by the archaic cable tool drilling method and were either known or considered to be “sanders”. 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, namely, faults which have offset and displaced the earth materials and created possible groundwater barriers; in addition, folds are present which have “bent” or “warped” the layers into different inclinations from the horizontal. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 19 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 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 mountain front on the north side of SMGB 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. Nonwater-Bearing Rocks Immediately beneath the San Pedro Formation (i.e., the bottom of which is 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 “nonwater-bearing;” albeit a few wells in the Lakewood area have been reported to obtain usable groundwater from the Pico 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) in 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. Well 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 older lithified and/or cemented, sedimentary rock Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 20 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 these rocks, 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 nonwater-bearing in the Santa Monica region and, therefore, these older formations and rocks are considered to be the local bedrock, and they are 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, and even between the subbasins which comprise the SMGB. A more detailed discussion of these local faults was provided in RCS (2013) and is presented herein strictly for information purposes, with regard to 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 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 21 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 most of the eastern boundary of SMGB and also that of its Crestal subbasin. 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 subbasi n ( o r w e s t e r n 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). 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 also 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 the SMGB and for the adjoining groundwater basins which lie to the east and south; and the names and boundaries for the subbasins within the SMGB, as determined by others (the subbasin boundaries are defined by the faults mentioned above). 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 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 22 Based on Figure 6, the area of the watershed, including the mountainous and hillside areas and the SMGB area, 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 SMGB surface area 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 from the Hollywood and Central groundwater basins to the east, and perhaps also from the WCB to 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). The amounts of such underflow are unknown, due to an absence of existing water wells and groundwater level data on each side of the subbasin and basin boundaries. Furthermore, a portion of surface water runoff along Ballona Creek is able to recharge the sediments of the shallow Ballona aquifer, but the majority 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 Verde Sand, the Silverado and the Sunnyside aquifers, is unknown. The Newport-Inglewood fault zone is considered to be, at least, a partial barrier to groundwater flow from the east to the west along the east side of the SMGB. 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 storage volume beneath the City. NATURAL RECHARGE The aquifer systems underlying the City are generally replenished by rainfall directly on the surface of the land, through percolation 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 23 Plain may have been significant along major canyons, such as Rustic, Santa Monica/Sullivan, Mandeville, Kenter, Sepulveda, Dry and Stone canyons, prior to urbanization of the region; during those prior times, surface water flowing along these canyons would likely have been able to readily percolate through the coarse-grained, gravelly and permeable alluvial fan sediments (at the canyon mouths), and eventually into the underlying aquifer systems. Since the early-1900s, urbanization of the entire region has clearly been extensive. Consequently, this has greatly reduced the amount of rainfall runoff that is able to percolate directly through the alluvial sediments and into the underlying aquifer systems. That is, the amount of rainfall runoff that would have previously percolated into the alluvial fans and along the creek channels that traverse the SMGB, now tends to flow along paved streets and into lined storm drains and lined stream channels, where it then flows directly to the ocean without having the ability to percolate into the land surface. However, the degree to which percolation has been diminished cannot be ascertained because of the lack of stream gage data. Indeed, because of this extensive urbanization near the mountain front, large surface areas for potential artificial recharge in the future are no longer even available. The only large areas that may currently serve as significant natural recharge areas to the SMGB are the Riviera Country Club (within Santa Monica Canyon), Brentwood Country Club just to the southeast, and Bel-Air Country Club near UCLA. Further, because a significant portion of the City has been extensively developed with homes and lawn areas, then the collective recharge through these lawns, proximal golf courses, City-owned parks, large school playgrounds/athletic fields, and landscaped street medians, helps to provide some additional areas for deep percolation and recharge of excess irrigation. However, the amount of natural and irrigation return water can only be estimated on a percentage basis to be on the order of perhaps 5% to 10% of the applied irrigation and of the rainfall that falls directly on these areas. In the south, Penmar Country Club (PGC) near Marine Park is the only other relatively large, flat, and unpaved area near the City that likely could serve as a natural recharge area. However, rainfall recharge here would only likely benefit the aquifer systems underlying the Ballona Gap. At the southern end of the SMGB, the Ballona Wetlands (along the Ballona Escarpment) constitute another significant recharge region, but recharge here would likely only benefit the aquifer systems at the northern end of the WCB, south of the SMGB. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 24 Recharge into the northern end of the WCB appears to be indicated in Figure 2.1 of the Regional Groundwater Monitoring Report for Water Year 2015-2016, as published by the Water Replenishment District of Southern California (WRD). That figure is reproduced herein as Figure 7, “Groundwater Elevation Contours of the West Coast & Central Groundwater Basins.” Review of Figure 7 reveals that due to pumping within the WCB, the overall direction of groundwater flow at the northern end of that basin is generally towards the southeast, between the Charnock and Newport Inglewood faults, as noted by the groundwater contours being 10 ft to 40 ft below mean sea level (msl) in the southeastern portion of the WCB, and at sea level at the extreme northern end of the WCB. Thus, this would seem to indicate that some component of groundwater is flowing from the southern portion of the SMGB into the WCB. However, the recharge is likely from the Ballona Gap area, but the degree to which groundwater in deeper formations from the northern portion of the SMGB flows into the WCB is wholly unknown. A future revision of this report may consider an estimate of the volume of precipitation available for potential natural recharge, based on the average rainfall volume for the basin over the 29 year baseline period. Review of water quality data from the WRD-owned Westchester 1 nested groundwater monitoring well indicates that the local groundwater appears to be slightly degraded with total dissolved concentrations (TDS) above 500 milligrams per liter (mg/L), in the period of 2002 through early-2017 (actual values ranged from 530 mg/L to as much as 1,390 mg/L, depending upon the depth of the monitoring port). The lowest TDS concentrations (average 550 mg/L) were from groundwater samples collected from the shallowest port at a depth of 215 to 235 ft bgs (likely the Ballona aquifer), whereas the highest TDS concentrations (average 1,031 mg/L) were from a port at 740 to 760 ft (in the Pico Formation). The monitoring well from which these data occur is located north of the northern terminus of the WCB injection barrier and it is not known to what extent injection of water along that barrier is influencing groundwater quality in this Westchester 1 groundwater monitoring well. ARTIFICIAL RECHARGE According to available records, the City conducted subsurface injection 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). Charnock Well No. 12 was used to Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 25 inject the imported MWD water to help replenish the aquifer systems in this Charnock wellfield area. However, that well was destroyed in the 1990s and water is no longer injected by the City into any well at its Charnock wellfield. Because of the degree of urbanization within the City and the surrounding groundwater subbasins, there appears, as mentioned previously, to be insufficient land area to conduct future artificial recharge, via the construction of spreading basins at ground surface. Indeed, the City historically has never conducted any artificial recharge operations using spreading basins. An alternative for the City to consider in the future is the use of Aquifer Storage and Recovery (ASR) wells to artificially recharge the local aquifer systems. A potential source of water for such injection is currently being developed in the City’s Sustainable Water Infrastructure Project (SWIP), which will create recycled water from the local sanitary sewers to be ultimately permitted for injection, to augment groundwater supplies. HYDROLOGIC BASELINE CONDITIONS Rainfall Totals Direct rainfall 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. Thus, RCS 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, in order to compare the data from each of the gages. The rain gages used in this study are: o Gage WR047953 at the Santa Monica Pier 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 actually 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. 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 26 2016 (depending on the rain gage, because the beginning year for each rain gage is 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 2016) ranges from 10.91 inches at the Santa Monica Pier rain gage, to 16.23 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 generally occurred at the Santa Monica Pier rain gage. O Annual rainfall totals from the Santa Monica Pier are somewhat spurious after ±2010/11. Accumulated Departure of Rainfall Figure 8B, “Accumulated Departure of Rainfall” (Appendix 1), shows the annual patterns in rainfall for the period of record of the various rain gages. 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 long-term patterns (or trends) in rainfall over time. It should be noted that such curves are not to be used in water resource planning studies or as a predictive tool. The basic purposes of such curves are to identify past trends in annual rainfall over time, and to allow comparison to trends in water levels 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 raingage data evaluated herein. O It can be readily seen for the Santa Monica Pier and Culver City rain gages that rainfall was skewed generally higher than their respective long-term averages, whereas for the UCLA and LAX rain gages rainfall was generally lower than their respective long-term averages. Selection of Baseline Hydrologic Conditions A key step in determination of the sustainable yield is the selection of hydrologic baseline conditions for a rainfall period that would be representative of long-term conditions, as obtained Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 27 from an accumulated departure curve. Specifically, the first step in determining the baseline is to select one of the four curves (presented on Figure 8B) which would be considered more representative of long-term hydrologic conditions in/near the SMGB than the others. In selecting such a baseline period from the selected accumulated departure curve, the following criteria should be met: o The period must include both hydrologically wet and dry cycles. o It should end near the present for which historical data are available. o The accumulated departure from mean annual precipitation should be similar for the beginning and end of the period. o Cultural conditions should be similar at the start and end of the period. o Adequate data need to be available throughout the period. From review of Figure 8B, it can be seen that two rain gages, the LAX and UCLA rain gages, have very similar trends over time, with respect to their accumulated departure percentages; on the other hand, the Santa Monica Pier rain gage shows a greater degree of accumulated departure (all generally above the long-term average). 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 other gages prior to the early-1980s. Further, review of the accumulated departure curves reveals that the period 1988 through 2016 may provide a better fit to the above criteria. Figure 9, “Selected Baseline Period,” shows that the 29-year period from 1988 through 2016 satisfies the above criteria, particularly for the Culver City and LAX rain gages, as follows: o The 29-year period for the Culver City and LAX rain gages includes both a hydrologically wet cycle and a hydrologically dry cycle. The years 1992 through 2010 may be considered the “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 extractions and static water levels for the 1988 through 2016 time period (see below). o The accumulated departure from mean annual precipitation occurs at approximately the same “level” in 1988 as it does in 2016 for two of the 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. The following compares the average historic rainfall to the average rainfall for the 1988 through 2016 for the four rain gages: Rain Gage Rainfall Average, Period of Record Rainfall Average 1988 - 2016 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 28 (inches) (inches) Santa Monica Pier 10.91 9.50 Culver City 12.00 11.88 UCLA 16.23 16.86 LAX 11.76 11.60 Review of the data for the Santa Monica Pier rain gage shows a difference of 1.41 inches and for the UCLA rain gage this difference is 0.63 inches. In comparison, the difference for the Culver City and LAX rain gages are 0.12 inches and 0.16 inches, respectively. Nonetheless the former two rain gages still generally satisfy the criteria, but to a lesser degree than the latter two rain gages. 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 86,905 in 1990 (US Bureau of the Census, 1992) to approximately 89,736 in 2010 (US Bureau of the Census, 2012); this is an increase of only 2,831 (or about 3%) persons during that time period. The current resident population is now around 93,000. Based on the four rain gages, the base period of 1988 through 2016 is a 29-year long period, including the beginning and end years of that interval. In this period, sufficient historical data are available from the various City wells, and for annual rainfall conditions, water levels, and groundwater extractions by the City. For this study, only one representative curve for the accumulated departure of rainfall was selected, namely the Culver City rain gage, because that curve is similar to the overall changes in the curves for the LAX and UCLA rain gages. Thus, the accumulated departure of rainfall curve for this Culver City rain gage will be used to help discern possible trends in the SWLs in City water-supply wells, as discussed below. GROUNDWATER EXTRACTIONS Extractions by 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 Totals by City Wellfields and Others (1988 through September 2016).” The tabulated values for historic total annual groundwater extractions during this 29-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. There have been no pumping City-owned wells in the Coastal or Crestal subbasins and, thus, there are no extraction data for these two subbasins. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 29 Table 3 presents data for the period of 1988 through 2016 hydrologic baseline period and shows the following: a) The Arcadia wellfield historically has and continues to be 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 400 AFY during the 29-year baseline period. b) The Charnock wellfield historically has and continues to be the most productive of the City’s three wellfields. Minimum and maximum groundwater extractions 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 29 years of data on Table 3, discounting the 13 years when the entire wellfield was purposely shut down, the long-term average annual extraction was approximately 5,884 AF. Conversely, when the shut-down period is excluded, the extraction volume was 8,750 AF for the same period. c) The Olympic wellfield has and continues to represent the second most productive of the three City wellfields. As seen on Table 3, 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 29-year baseline period was 1,870 AF. The total extractions 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 production during the 29-year baseline period has been on the order of ±5,500 AFY for all City wells (see Table 2). However, if those years in which zero groundwater production were not figured into the baseline period average, then the average annual extractions by the City from the three subject subbasins would be ±8,750 AFY. This is slightly above the current sustainable yield estimate of 8,200 AFY. Extractions by Others The only other known existing groundwater extractions occurring in the subbasins being evaluated herein are from the known water wells at two golf courses, namely the Brentwood Country Club (BCC), and the Riviera Country Club (RCC). Because both golf courses lie 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). Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 30 With the assumptions above, RCS used computer methods and Google Earth® imagery and determined that the total irrigated areas of turf are on the order of 105 acres for the BCC golf course, and 125 acres for the RCC golf course. Further, in coastal areas of southern California, it is reasonable to assume that each acre of golf course turf requires approximately 2.5 AF of water for irrigation each year. Hence, 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 two golf courses could be as follows: 310 AF for RCC; and 260 AFY for BCC (note that these values assume that any/all golf course wells at those golf courses have been in active use throughout the entire 29-year baseline period being used herein). Thus, total extractions by others in the Arcadia subbasin are ±570 AFY. Note that although it is known that the Los Angeles Country Club has active irrigation-supply wells, the total groundwater extractions by those wells are not being included herein, because that golf course lies within the Crestal subbasin. The same would be true for any possible water-supply wells located at UCLA. 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 also 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 wells. These hydrographs have been plotted along with the accumulated departure of rainfall for the base period using the Culver City rain gage, in order to illustrate the comparison between changes in water levels and changes in rainfall. 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 that subbasin over time. For this current study, historic SWL data from the previous RCS (2013) report were updated with more recently obtained data for City wells, as provided by City staff. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 31 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). Review of Figure 10A, “Arcadia Wellfield/Subbasin Hydrographs,” show 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 data (or 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 time 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 Olympic subbasin to the south. Charnock Wellfield/Subbasin. Figure 10B, “Charnock Wellfield/Subbasin Hydrographs,” illustrates the water level data for seven City wells in this wellfield (see 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 Charnock wells tend to have similar depths and similar perforated intervals, their SWL depths and trends over time are seen to be very similar on Figure 10B, as expected. Water level data for Charnock Well Nos. 7 and Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 32 15 are provided on Figure 10B, even though those wells have been destroyed; construction data for these two wells are not listed on Table 1. Notably, Well No. 7 has the longest period of available water level data of any well shown on Figure 10B. It is apparent on Figure 10B that the water wells in the Charnock wellfield show some response to changes in rainfall. For example, SWLs for Well No. 7 between 1937 and 1955 appear to show some 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, SWLs are generally declining, whereas the accumulated departure of rainfall shows increasing rainfall conditions. Between 1970 and 1995 the data are inconsistent and lacking (possibly due to including some water level measurements that are actually pumping water levels and not SWL). However, in 1996 the water level data for the majority of the wells become consistent, and all show a slow and continuous rise over time; this 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 ±2011, due to groundwater contamination within/near the Charnock wellfield. Since the pumps in the seven active wells were turned back on in ±2011, water levels in those wells have generally declined rapidly as a result of the ongoing drought in the area and the geologic characteristics of the aquifer. Olympic Wellfield/Subbasin. There are three existing wells in this wellfield, all being located within a median along Olympic Blvd (see Figure 3B). Two of these, Santa Monica Well Nos. 3 and 4, are active, whereas Well No. 7 has been abandoned but is being used as a water level observation well. These are the only known water wells in this subbasin. Figure 10C, “Olympic Wellfield/Subbasin Hydrographs”, graphically depicts the water level patterns of the three wells over time. That figure shows that the water levels from the three wells have had similar depths and trends over time; Well No. 7 has tended to exhibit slightly deeper water levels than those in the other two wells. Comparing the SWLs to the accumulated departure of rainfall for the Culver City rain gage, it may be seen for the 1979 through 2016 period of record for SWLs for the wells that the data correspond, but there is a significant 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 SWLs in these wells does not commence until around 1996. Thus, there appears to be a three- to four- year offset between changes in rainfall and changes in SWLs. However, this relationship does not occur elsewhere in these wells (see earlier data from 1979 through 1992). o Coastal Subbasin. There are three existing wells in this subbasin; however, none of these are active, municipal-supply water wells. Two of these, Saltwater Well Nos. 1 and 2, are located near Santa Monica Beach near the west terminus of Pico Blvd, whereas the Marine Park well is located near the PGC at Marine Park. Saltwater Well Nos. 1 and 2 formerly produced brine for a former treatment system at the Arcadia Wellfield, but they are no longer used. Based on the data, these wells are not representative of aquifer conditions. Thus, for many years, none of these wells has been pumped; instead, they have functioned solely as water level observation Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 33 wells. As noted above, there are no historic or currently-existing, active, municipal- supply water wells in the Coastal Subbasin. Water Level Hydrographs – “Key” Well Concept In comparing the SWL data in the wells to the baseline period and, ultimately, to determine 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 group. SWL data for this key well reflect water level changes that are similar to the others, and this well also has the longest and most complete period of record for the baseline period, in comparison to the other wells. Figures 11A through 11C, in Appendix 1, provide graphs of the available SWL data versus time for “key” selected City wells in each of the groundwater subbasins of the SMGB, for which data are available, for the 1988 through 2016 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 SWL 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 SWLs 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 Hydrographs Figure 11A, “Key Well Hydrograph, Santa Monica Well No. 5”, is a key well hydrograph based on data obtained from Santa Monica Well No. 5 (located in the central portion of the Arcadia subbasin, in the northern portion of the City). Data from this well was selected as being representative of changes in water levels in the Arcadia subbasin. This hydrograph is plotted along with the accumulated departure of rainfall for the Culver City rain gage (as adapted from Figure 9) for comparative purposes. Figure 11A reveals the following: Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 34 o The response of the SWLs to increases in rainfall is illustrated in the figure by the successive “up & down” patterns (i.e., rises and declines), noted by the sawtooth pattern in those SWLs. On an annual basis, the SWLs are 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 SWLs is immediate; 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 appears to indicate that this well contains at least part of its perforations within a shallow, unconfined (water table) aquifer system. Also of interest is that the SWL 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 SWLs (represented by the symbol ΔS on the graph) during the baseline period, then the difference in the SWLs between the beginning and the end of the baseline period can be defined. This difference amounts to -18 ft on the graph; this represents an overall decline in SWLs from the beginning to 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 which had adequate available historic data to permit a determination of changes in SWLs for the baseline period, namely Charnock Well No. 16; the resulting data are shown in Figure 11B, “Key Well Hydrograph for Charnock Well No. 16.” Review of this figure reveals the following: 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 period during which the entire Charnock wellfield was shut down due to contamination of local groundwater by a third party. In essence, 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, SWLs once again began to experience a steep and rapid decline to depths of 155 to 156 ft brp (by late-2016). o Also in Figure 11B, the response between changes in rainfall and changes in the SWL is not as noticeable as that noted above for the hydrograph on Figure 11A. For example, between 1987 and mid-1992, there appears to be a declining trend in the accumulated departure of rainfall curve. o Beginning in late-2010 when the wellfield became operational again, SWLs abruptly declined. Further, SWLs continued to decline to early-2016, which coincides with declining rainfall during the same period, as shown in the accumulated departure curve (note that there is a significant lack of SWL measurements between 2012 and early-2016 because the well was in continuous operation during this entire time period). Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 35 Thus, it appears that SWL responses in the well appear to be more affected by pumping than by rainfall and that water level changes are prone to the vagaries of when and how frequent SWL measurements were and are collected. o The total change in water levels during the baseline period, represented by the symbol ΔS which is the difference in SWLs at the beginning and the end of that period, amounts to +3 ft; this represents a water level rise between the beginning and end of that baseline period. This significance of this calculation is discussed in greater detail in the section below titled “Subunit/Subbasin Changes in Groundwater in Storage Calculations”. Olympic Subbasin Key Well Hydrograph There are only three City wells in this subbasin for which there are available water level data and those data for Santa Monica Well No. 7 are considered to be more representative as an indicator of SWL changes in this subbasin for the baseline period; Figure 11C, “Key Well Hydrograph for Santa Monica Well No. 7,” illustrates those changes. This Well No. 7 is considered to be representative because it has a more complete and continuous SWL record than the other two wells in this subbasin for the baseline period; notably, after mid-1998 it appears that no pumping from this well was performed, making it more difficult to determine the change in the amount of groundwater in storage in this subbasin over that baseline period. Further, this well has perforations set at depths similar to those in nearby Santa Monica Well Nos. 3 and 4. Regardless, from roughly 1993 until the present, SWLs in Well No. 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 SWLs that may not have been measured during or heavily influenced by 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 similar to those for Santa Monica Well No. 5 in the Arcadia subbasin. This fact is noticeable after 2010, when both rainfall and SWLs each show a declining trend through to the Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 36 end of the baseline period. However, correlation of SWLs to trends in rainfall is not well defined prior to that date. o The total change in water levels during the baseline period (symbol ΔS), is noted to be -26 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”. Coastal Subbasin Key Well Hydrographs There are no 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 of the ocean are the principal cause of changes in SWLs in these wells, and they are too shallow to provide any other useful information for estimating sustainable yield of this subbasin. The City has recently (November 2016) constructed a new, low production-rate well in this subbasin (at 8-10 gpm), which is to be used to meet the limited water demands at City Hall. Specifically, this new well is for use by a special City sustainable building project called the City Services Building, which reportedly will require only approximately 10,000 gallons/day. The well, as constructed, is very shallow and was cased to a depth of only 160 ft bgs, with perforations being placed 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 and, thus, this well has very limited use with regard to determination of ΔS in this subbasin. However useful hydrogeologic data were obtained from the drilling and construction of this well. The borehole for the well was drilled to a total depth of approximately 652 ft bgs; 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 approximately 280 ft to 300 ft bgs. The base of fresh water was identified on the electric logs to be at a depth of approximately 540 ft bgs at this site. In order to further assess Coastal subbasin geology and its groundwater, the City is in the process of drilling three 600-foot deep exploratory borings in this subbasin during the summer- fall of 2017. These data will be utilized to help update future versions of this report. Crestal Subbasin Key Well Hydrograph Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 37 Currently, there are no 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. GROUNDWATER IN STORAGE Storage Subunits and Parameters The locations and alignments of several faults in the SMGB, as mentioned in various geologic publications and also 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. Details regarding this potential is found in the RCS (February 2013) report and much of the rationale and the calculations in that report are repeated herein. 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 cannot be evaluated at this time because the City has never, and does not currently, obtain any of its groundwater supply from this subbasin. Further, there is also a complete absence of requisite data available for this subbasin. In generally determining the 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 that the western boundary of any/all of these subbasins occurs generally along Lincoln Blvd 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, and not the basin(or subbasin) writ large. In this current report, the locations and names of the Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 38 usable groundwater storage subunits are shown in Figure 12, “Usable Area of Groundwater Storage Subunits.” o Saturated Thickness: This is a time-dependent value and is based on the depth to SWLs (for a specific time 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 (2013) report. Calculations of the saturated thickness are based on water level conditions during the baseline period. Thus the groundwater is storage can be calculated for any one particular 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 basin/subbasin. 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 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 over the baseline period, then this quantity is replaced by the change in water levels, or ΔS value, determined above. 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 particular subbasin. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 39 The above calculates the amount of groundwater in storage in the units of cubic feet (ft3) of water, and these 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, with regard to calculating the area of usable groundwater in storage. That is, generally, Lincoln Blvd was conservatively determined to be the westernmost boundary for the available groundwater in storage in the region, whereas the southern boundary was determined to be along Washington Blvd. Figure 12 shows the approximate boundaries of the “usable” groundwater storage subunits delineated for this current study. Two methods of determining the amount of change in groundwater in storage were used in this evaluation, as follows: Method 1: The change in groundwater in storage was calculated based on the entire hydrologic baseline period, or the full 29 years of data for which extraction data were available. Thus, in this case, the change in water levels was determined by finding the difference in SWLs between the beginning and the end of the 1988 through 2016 time period. Here it is assumed that the average volume of all groundwater extractions over this time period represents the production by the City and by private parties, as applicable, over all 29 years for each subbasin with requisite data. This method is explained more thoroughly below. Method 2: The change in groundwater in storage was calculated based on the two separate time periods during which no groundwater extractions were occurring by the City in the Arcadia and Charnock subbasins. In these two subbasins, pumping ceased at a point approximately midway in the 29-year period of record. In this case, the change in water levels was determined for each of the two separate periods by finding the difference in SWLs between the beginning and end of the two separate time periods. This method is also explained more thoroughly below. Method 1: Change in Groundwater Storage for the Entire Hydrologic Baseline Period 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 area. The following discusses the methodology for calculating the amount of change of groundwater in storage for this groundwater subunit/subbasin: Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 40 o Area of Subunit: The entire area calculated for this subunit was based on that region of the subbasin that was considered to be available to the City for extraction of groundwater. The western border of this area is taken along Lincoln Blvd and the 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 Water 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 considered to be 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 2016). The hydrograph for this well (Figure 11A) indicates that ΔS, the change in water levels over the baseline period (based on data for Santa Monica Well No. 5) was on the order of -14 ft (i.e., SWLs declined by 14 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 the period in late-2016. 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%. Table 3A, “Preliminary Calculations of Change in Groundwater in Storage During the Baseline Period for the Arcadia, Charnock and Olympic Groundwater Subbasins (Method 1 Calculations)” lists the resulting RCS calculations for available groundwater in storage and for 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 Coastal or Crestal subbasins have been provided because of the paucity of data for these areas. Preliminary values for sustainable yield might be able to be determined for the Coastal subbasin in the future, following the drilling of three deep exploratory borings by the City in summer-fall of 2017. As noted above, that drilling project is oriented to provide hydrogeologic data that could be utilized to provide estimates of available water in this subbasin. The RCS calculations for the changes in groundwater in storage are a conservative estimate and should only be considered as preliminary values at this time; as more subsurface data become available, these values will be further refined, especially those estimates for the Crestal and Coastal subbasins for which meaningful data are currently lacking. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 41 Notably, the total usable subbasin area for use by existing and future City wells at this time within the listed subbasins is shown to be approximately 13.4 sq mi. Table 3A shows that the change (in this case a decline as denoted by the negative number in Table 3A) in the groundwater in storage for the 1988 through 2016 hydrologic baseline period for the Arcadia subbasin shows a decline of 6,100 to 9,100 AF. For the 29-year baseline period, the average annual decline has been on the order of 200 to 300 AFY for this subbasin, using these Method 1 calculations. Charnock Groundwater Storage Subunit 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 and 19. Of these five 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). o Area of Subunit: This groundwater storage subunit, as measured f o r t h i s c u r r e n t 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, shows that at the beginning of the baseline period the SWL was 130 ft bgs, whereas at the end of the baseline period, the SWL was at 148 ft bgs. This represents a total change in water levels of -18 ft, or a decline 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 16% for this subbasin. Table 3A, shows that the change (in this case an increase as denoted by a positive set of numbers in Table 3A) in the groundwater in storage for the 1988 through 2016 hydrologic baseline period for the Charnock subbasin is on the order of 900 to 1,000 AF. For the 29-year baseline period, the average annual increase has been on the order of 30 to 40 AFY for these Method 1 calculations. Olympic Groundwater Storage Subunit This 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 42 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; with the western boundary set at Lincoln Blvd. o Change in Water 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 144 ft bgs in 2016. Thus, ΔS amounts to approximately -26 ft in that well for the hydrologic baseline period. The negative number reflects a decline in the change in water levels across this subbasin. 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 3A, shows that the change (decline) in the groundwater in storage for the 1988 through 2016 hydrologic baseline period for the Olympic Subbasin shows 5,200 to 7,700 AF. For the 29-year baseline period the average annual decline has been on the order of 400 to 600 AFY. Method 2: Change in Groundwater Storage for a Split Hydrologic Baseline Period The change in groundwater storage was also calculated for two of the local groundwater subbasins, namely the Arcadia and Charnock subbasins, because there were some years in those two specific subbasins when groundwater extractions by City wells were not being conducted (See Table 2, above). There was no cessation of pumping in the Olympic subbasin by the City and, thus, the calculated values for change in storage for this subbasin do not change from one method to another; thus, a second set of calculated values for Olympic subbasin is not included in Table 3B, but can be seen in Table 3A for this subbasin. Consequently, RCS performed calculations to compare the values from this method to those in Method 1, discussed above. Specifically, Table 3B, “Preliminary Calculations of Change in Groundwater in Storage During Split Baseline Period (Method 2 Calculations),” shows the resultant calculations for Method 2. Arcadia Groundwater Storage Subunit/Subbasin In the calculation for groundwater in storage changes for this subbasin, the same parameters for the area of the subunit and the specific yield of the sediments, as were used above in the Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 43 Method 1 calculation, are utilized herein. However, the calculations for this subbasin are based on the changes in storage for the split baseline period as shown on Figure 13A, “Key Well Hydrograph, Santa Monica Well No. 5, Arcadia Subbasin, Split Baseline Period.” This figure shows the changes in storage values (in ft) for the two split sections of the baseline: one split section was before pumping stopped; and one section was after pumping resumed. These two values were then arithmetically combined to provide the calculations as shown in Table 3B for the Arcadia subbasin. The hydrograph for available SWL data for Santa Monica Well No. 5 (Figure 13A) indicates that ΔS, the change in water levels over the baseline period was on the order of 3 ft (from 1988 through 1996), and -22 ft from 2001 through 2016. These two values calculate to a value of -19 ft (an overall decline) for the two split periods of record, as shown on Table 3B. Based on the calculations for this split value, the change (decline) in the groundwater in storage for the 1988 through 2016 hydrologic baseline period for the Arcadia subbasin ranges from -6,400 to -9,600 AF. For the split 25-year baseline period (excluding the 4 years where pumping was not performed) in the Arcadia subbasin, the average annual decline has been on the order of -300 to -400 AFY. Charnock Groundwater Storage Subunit/Subbasin As noted above for the Arcadia subbasin, the same parameters for the area of the subunit and the specific yield of the sediments used in the Method 1 calculation are also used for the split calculations for the Charnock subbasin. Figure 13B, “Key Well Hydrograph, Charnock Well No. 16, Charnock Subbasin, Split Baseline Period,” shows the changes in storage values (in ft) for the two split sections of the baseline and the two values were then arithmetically combined to provide the calculations as shown in Table 3B for this subbasin. The hydrograph for available SWL data for Charnock Well No. 16 (Figure 13B) indicates that ΔS, the change in water levels over the baseline period, was 26 ft (from 1988 through 1996), and -80 ft from 2010 through 2016. These two values calculate to a ΔS value of -54 ft (a decline) for the combined split periods of record, as shown on Table 3B. Based on the calculations for this split value, the change (decline) in the groundwater in storage for the 1988 through 2016 hydrologic baseline period for the Arcadia subbasin ranges from -15,300 to - 20,500 AF. For the split 25-year baseline period (excluding the 13 years when pumping was not Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 44 performed by the City in the subbasin) the average annual ΔS decline has been on the order of -1,000 to -1,300 AFY. Change in Groundwater Storage for the Coastal Subbasin The City currently does not have any active wells in this subbasin. However, in the summer-fall of 2017, the City is planning to drill three deep exploratory borings in this subbasin to evaluate the local occurrence and quality of groundwater. These data will be utilized to help update a future version of this report. Below are preliminary estimates of the various hydrogeologic parameters. However, long-term water level and pumpage data will still need to be obtained to calculate the changes in storage in this subbasin. As this will require additional years of pumpage and water level monitoring, 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: 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. These values could be reassessed following the evaluation of the drill cuttings and electric logs from the three currently- proposed exploratory boreholes. PRELIMINARY CALCULATIONS OF SUSTAINABLE (PERENNIAL) YIELDS As previously mentioned, sustainable yield is considered to be analogous to perennial yield, and it is a dynamic value, which can change under varying conditions of annual pumping and trends in rainfall over time. Thus, if sufficient groundwater extraction data and SWL data are available, then the sustainable yield for each subbasin with requisite data can be determined in the following manner: Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 45 (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 extractions by known water wells. Table 4A, “Preliminary Calculations of Sustainable Yield, Three Santa Monica Subbasins (Method 1 Calculations),” provides the calculated values for sustainable yield, based on the available data and for the Method 1 calculations presented above, for the entire 29-year baseline period. These data show that sustainable yield values determined based on the entire that baseline period range from as low as 700 AFY for the Arcadia subbasin, to as high as 5,940 AFY for the Charnock subbasin (note that these values have been rounded to the nearest 100 AF). Table 4B, “Preliminary Calculations of Sustainable Yield, Two Santa Monica Subbasins (Method 2 Calculations),” provides the calculated values for sustainable yield, based on the available data and for the Method 2 calculations presented above, for the split baseline period defined for the Arcadia and Charnock subbasins, in which there was a cessation of pumping by the City for several years (again, a separate calculation for the Olympic subbasin is not included in Table 4B because pumping has been continuous over the years in this subbasin). Table 4B shows that the sustainable yield values, based on the split baseline periods, range from 600 AFY for the Arcadia subbasin, to 4,900 AFY for the Charnock subbasin. DISCUSSION OF HISTORICAL VALUES BY OTHERS Comparison of Sustainable Yield Values Table 5, “Comparison of Sustainable Yield Values, Santa Monica Subbasins (Using Methods 1 and 2),” tabulates and compares the results of this study (using the two aforementioned methods of calculation) to previous studies conducted by RCS (2013) and others. The table shows the comparison of the two as follows: o Arcadia Subbasin: 600 to 800 AFY vs a previously-estimated 2,000 AFY by others. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 46 o Charnock Subbasin: 4,600 to 5,900 AFY vs the previously-determined values of 4,420 to 8,200 AFY by others. o Olympic Subbasin: 1,600 to 1,700 AFY, vs the previous value of 3,275 AFY estimated by others. Overall, the total combined sustainable yield values, based on the two methods of calculations in this current study, amounts to 6,800 to 8,400 AFY for the Arcadia, Charnock, and Olympic subbasins; totals from previous studies ranged from 9,695 to 13,475 AFY for these same three subbasins. As noted above, sustainable yield values for the Coastal and Crestal subbasins could not be determined in this current study because of the complete lack of available data (nonetheless, the previously-determined values for these two other subbasins are also provided on Table 5). 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 areas currently encompassing 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, consisted also of the present Arcadia and Olympic subbasins, whereas their Coastal subbasin boundaries are similar to the current ones. In their model, changes in water levels were compared to groundwater extraction volumes by KJC to determine the sustainable yield of the SMGB and its subbasins. KJC’s stated assumptions were that under constant extraction 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 extraction rates, then the sustainable yield of the basin was being exceeded. KJC’s statistical evaluation involved plotting water levels versus groundwater extraction 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 levels elevations vs. basin extraction rates (in AFY). o Annual extractions (in AF) and water level elevations vs. date (years). o Average annual water level elevations and pumping rates (in AF) vs. date (years). Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 47 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 gradients (using the USGS MODFLOW computer modeling program) and groundwater in storage. Using the above analyses/estimation techniques for KJC’s combined Charnock subbasin 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 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, as 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 600 to 800 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. Review of the KJC (June 1992) report reveals they provided a range of 6,000 to 6,500 AFY (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 through the use of two methods, namely: o A “Direct Correlation” approach, which estimates 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 Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 48 this line were considered to correspond to a no net inflow or 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 higher than the production. Using this method, Komex arrived at a value of 9,244 AFY for the Charnock subbasin. o A three dimensional numerical model of the Charnock subbasin, using software based on the USGS MODFLOW program. Their model was also based on extraction 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. It is important to note that Komex ran “overdraft” modeling scenarios to determine the amount of water that could be extracted from this subbasin. Key points of their modeling of the Charnock subbasin included the following: 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 120 ft below mean sea level (msl). This represents a depth of approximately 217 ft bgs, based on an average elevation of 97 ft above msl for the Charnock wellfield. The RCS-calculated decline was 98 ft for the baseline period, whereas the Komex decline is 142 ft; thus, this partially accounts for the difference in the two sustainable yield calculations. o Water levels could be drawn down to 200 ft below msl (or 297 ft below msl), which was considered to be 50% of the thickness of the Silverado aquifer. 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, assuming an assigned specific yield value of 12% over an area of 4,200 acres. 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 extraction values and SWL depths for the 1931 through 1950 time period (Komex, 2001, p. 3). In March 2013, RCS estimated the preliminary sustainable yield of the Charnock subbasin to more or less conform to the Komex 2001 estimate of 8,200 AFY. This current RCS study, Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 49 however, has calculated a sustainable yield value based on measured water levels and known groundwater extractions during a specific baseline period that differs from the one used by Komex. The estimated sustainable yield for the Charnock subbasin derived by RCS in this current study is 4,600 to 5,900 AFY (see Tables 4 & 5). 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. The current value of 1,600 to 1,700 AFY is based on observed changes in measured groundwater levels and average groundwater extraction amounts over the hydrologic baseline period defined herein. 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. Currently, there are little available data on pumping rates and changes in SWLs from prior production wells from the Coastal subbasin, and determination of a sustainable yield value is not possible until additional data are obtained by future drilling and construction of wells in this subbasin and until long-term changes in water levels can be documented. Thus, the above value may remain valid, pending additional data and analysis. 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 study herein has not been able to arrive at a range of values, because of a total lack of available data. Until such time as additional data are obtained for the Crestal subbasin, the previous value of 2,000 AFY may be valid. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 50 CONCLUSIONS & RECOMMENDATIONS Based on available water level and groundwater extraction 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: 600 AFY to 800 AFY for the Arcadia subbasin, 1,600 to 1,700 for the Olympic subbasin, and 4,600 to 5,900 AFY for the Charnock subbasin. The Coastal and Crestal subbasins have not been included in this estimate because of the lack of available data to quantify the sustainable yield in these two subbasins; in this regard, planned exploratory drilling in the Coastal subbasin, scheduled for Summer/Fall 2017 may indicate the availability of additional water supplies Average subbasin extractions over the 29 year baseline period analyzed in this report are: o Arcadia subbasin: 365 - 424 AFY. o Charnock subbasin: 3,250 - 5,900 AFY o Olympic subbasin:1900 AFY Third party extractions, primarily from two golf courses, have also occurred in the Arcadia subbasin. When these withdrawals are included, the extractions for that subbasin are estimated be on the order of 1,000 AFY. Average withdrawals from the Charnock and Olympic subbasins between 2011 and 2016 have been around 9,757 and 2,017 AFY, respectively. For example, the increased production from the Charnock well field was made possible by the recharge in the basin during the non-pumping period from 1996 – 2010. While there may be additional groundwater in storage throughout the basin that might allow for some greater amount of groundwater extractions from these subbasins, it would likely only be for short periods of time. Such pumping, if conducted too long, 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 (such cascading conditions causes the pumped groundwater to become aerated and have a milky white color, and induces cavitation problems in pumps). The City must continue to be diligent about is ongoing program to monitor and record SWLs (and total pumped groundwater extractions) for each of its wells in the Arcadia, Charnock, and Olympic subbasins. As such, the sustainable yields calculated in this current study will be further refined over time. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 51 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 additional water supply in 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 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 Costa 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 well fields 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 stormwater runoff, brackish/saline groundwater and municipal wastewater. The City is in the process of beginning construction of its Clean Beaches Project which will install a below grade 1.6 million gallon stormwater 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, for indirect potable reuse via aquifer recharge. The Clean Beaches Project is scheduled for completion in 2018. Awaiting funding in 2017 is the City’s Sustainable Water Infrastructure Project. The SWIP is comprised of three integrated elements that once constructed will produce approximately 1,120 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 in order 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 52 REFERENCES REVIEWED Broedhoeft, 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. 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, 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. Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin Los Angeles County, California 53 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. 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 2015-2016, Central and West Coast Basins, Los Angeles County, California. APPENDIX 1 FIGURES 90 450 Scale (in miles) 20 Scale (in miles) FIGURE 1 LOCATION MAP OF STUDY AREA RCS Job No. 462-LASOC July 2017 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 FIGURE 2 MAP OF DWR GROUNDWATER BASINS RCS Job No. 462-LASOC July 2017 8 40 Scale (in miles)Adapted from DWR (1965) City Boundary 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          Crestal Crestal Crestal Crestal Crestal Crestal Crestal Crestal Crestal Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin Subbasin I-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0CENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRALCENTRALGROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k I -40 5I-40 5I-40 5I-40 5I-40 5I-40 5I-40 5I-40 5I-40 5 90 F W Y 90 F W Y 90 F W Y 90 F W Y 90 F W Y 90 F W Y 90 F W Y 90 F W Y 90 F W Y Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n C h a r n o c k S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i nCharnock S u b b a s i n WEST COAST WEST COAST WEST COAST WEST COAST WEST COAST WEST COAST WEST COAST WEST COAST WEST COAST GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN I -40 5 I -40 5 I -40 5I-40 5 I -40 5I-40 5 I -40 5 I -40 5 I -40 5 Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S 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 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 7 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Charnock No. 13 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Richard C. Slade & Associates LLC 14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401 Phone: (818) 506-0418 Fax: (818) 506-1343Figure 3B Well Location MapConsulting Groundwater Geologists Date:July 2017Project No: 462-LASOC Author: LAB/JA Projection: Custom ProjectionFilename: Figure 4 Watershed Map  Le g e n d Ci t y W e l l Ke y W e l l w i t h H y d r o g r a p h D a t a Na m e a n d a p p r o x i m a t e B o u n d a r y o f G r o u n d w a t e r B a s i n (a s d e f i n e d b y D W R B u l l e t i n 1 1 8 U p d a t e 2 0 0 3 )  Su b b a s i n B o u n d a r y 10 1 2 Mi l e s  FIGURE 4A GENERALIZED GEOLOGIC MAP OF THE SANTA MONICA AREA RCS Job No. 462-LAS01 July 2017 4 20 Scale (in miles)Adapted from DWR (1961) City Boundary Ballo n a E s c a r pme n t Baldwin Hills N e w p o r t - I n g l w o o d F a u l t Z o n e Santa Monica Basin Boundary 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 FIGURE 4B GENERALIZED GEOLOGIC MAP LEGEND & SYMBOLS RCS Job No. 462-LAS01 July 2017 Adapted from DWR (1961) 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 FIGURE 5 GENERALIZED STRATIGRAPHIC SECTION FOR THE COASTAL PLAIN OF LOS ANGELES COUNTY RCS Job No. 462-LAS01 July 2017 Miralom a A venue Servic e R o a d Public P a r k i n g Area Modified from DWR Bulletin 104 (1961) RICHARD C. 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CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN I -4 0 5 I -4 0 5 I -4 0 5I-4 0 5 I -4 0 5I-4 0 5 I -4 0 5 I -4 0 5 I -4 0 5 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 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 U T F L O W O F O F O F O F O F O F O F O F O F 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 B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 I- 10 Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA 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 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a N o . 4 Sa n t a M o n i c a N o . 4 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Sa n t a M o n i c a N o . 3 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 4 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Ar c a d i a N o . 5 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 6 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 5 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Sa n t a M o n i c a N o . 1 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 3 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 6 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 8 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 9 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Ch a r n o c k N o . 1 5 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Sa l t w a t e r N o . 2 Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Ci t y H a l l W e l l Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Sa l t w a t e r N o . 1 Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Cu l v e r C i t y Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Sa n t a M o n i c a Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e UC L A R a i n G a g e Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ge t t y M u s e u m Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e Ra i n G a g e LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain Gage LAX Rain GageRichard C. Slade & Associates LLC 14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401 Phone: (818) 506-0418 Fax: (818) 506-1343Figure 6 Map of Watershed and Local DrainageConsulting Groundwater Geologists Project No: 462-LASOC Author: LAB/JA Projection: Custom ProjectionFilename: Figure 12 Date:July 2017  Le g e n d Ci t y W e l l Ke y W e l l w i t h H y d r o g r a p h D a t a Na m e a n d a p p r o x i m a t e B o u n d a r y o f G r o u n d w a t e r B a s i n (a s d e f i n e d b y D W R B u l l e t i n 1 1 8 U p d a t e 2 0 0 3 ) Ci t y B o u n d a r y Ra i n G a g e s Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Su b b a s i n B o u n d a r y Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Ap p r o x i m a t e F a u l t Z o n e Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n an d C r e e k s f r o m W a t e r s h e d R e g i o n 10 1 2 Mi l e s  FIGURE 7 GROUNDWATER ELEVATION CONTOURS OF THE WEST COAST & CENTRAL GROUNDWATER BASINS RCS Job No. 462-LAS01 July 2017 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 0 5 10 15 20 25 30 35 40 45 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 Yearly Rainfall Totals Santa Monica Pier (AVG. 10.91) Yearly Rainfall Totals LAX (AVG. 11.76) Yearly Rain Fall Totals Culver City (AVG. 12.00) Yearly Rainfall Totals UCLA (AVG. 16.23) 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 An n u a l R a i n f a l l T o t a l s ( I n c h e s ) 2020 Job No. 462-LASOC July 2017 -400 -200 0 200 400 600 800 1000 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Accumlated Departure Santa Monica Pier (AVG. 10.91 inches) Accumlated Departure Culver City (AVG. 12.00 inches) Accumlated Departure LAX (AVG. 11.76 inches) Accumlated Departure UCLA (AVG. 16.23 inches) FIGURE 8B ACCUMULATED DEPARTURE OF RAINFALL Job No. 462-LASOC July 2017 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 Ac c u m u l a t e d D e p a r t u r e o f R a i n f a l l ( % ) Calendar Year “Dry”“Wet”“Wet”“Wet”“Dry”“Dry” “Hydrologic Periods” Selected Baseline Period -400 -200 0 200 400 600 800 1000 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 Accumlated Departure Santa Monica Pier (AVG. 10.91 inches) Accumlated Departure Culver City (AVG. 12.00 inches) Accumlated Departure LAX (AVG. 11.76 inches) Accumlated Departure UCLA (AVG. 16.23 inches) FIGURE 9 SELECTED BASELINE PERIOD Job No. 462-LASOC July 2017 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 Ac c u m u l a t e d D e p a r t u r e o f R a i n f a l l ( % ) Calendar Year “Hydrologic Baseline Period” FI G U R E 1 0 A AR C A D I A W E L L F I E L D / S U B B A S I N HY D R O G R A P H S D e p t h t o W a t e r L e v e l ( f t b r p ) Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 Accumulated Departure of Rainfall -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 50 10 0 15 0 20 0 25 0 19 3 0 1 9 3 5 1 9 4 0 1 9 4 5 1 9 5 0 1 9 5 5 1 9 6 0 1 9 6 5 1 9 7 0 1 9 7 5 1 9 8 0 1 9 8 5 1 9 9 0 1 9 9 5 2 0 0 0 2 0 0 5 2 0 1 0 2 0 1 5 2 0 2 0 Ye a r Ar c a d i a W e l l N o . 2 S W L M e a s u r e m e n t s Ar c a d i a W e l l N o . 4 S W L M e a s u r e m e n t s Ar c a d i a W e l l N o . 5 S W L M e a s u r e m e n t s S a n t a M o n i c a W e l l N o . 1 S W L M e a s u r e m e n t s S a n t a M o n i c a W e l l N o . 5 S W L M e a s u r e m e n t s Ac c u m u l a t e d D e p a r t u r e o f R a i n f a l l - C u l v e r Ci t y G a g e FI G U R E 1 0 B CH A R N O C K W E L L F I E L D / S U B B A S I N HY D R O G R A P H S Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 D e p t h t o W a t e r L e v e l ( f t b r p ) Accumulated Departure of Rainfall -400-300-200-1000100200300400500600 0 50 10 0 15 0 20 0 25 0 19 3 0 1 9 3 5 1 9 4 0 1 9 4 5 1 9 5 0 1 9 5 5 1 9 6 0 1 9 6 5 1 9 7 0 1 9 7 5 1 9 8 0 1 9 8 5 1 9 9 0 1 9 9 5 2 0 0 0 2 0 0 5 2 0 1 0 2 0 1 5 2 0 2 0 Ye a r Ch a r n o c k W e l l N o . 7 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 1 3 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 1 5 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 1 6 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 1 8 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 1 9 S W L M e a s u r e m e n t s Ch a r n o c k W e l l N o . 2 0 S W L M e a s u r e m e n t s Ac c u m u l a t e d D e p a r t u r e o f R a i n f a l l - C u l v e r C i t y G a g e -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 50 10 0 15 0 20 0 25 0 1 9 3 0 1 9 3 5 1 9 4 0 1 9 4 5 1 9 5 0 1 9 5 5 1 9 6 0 1 9 6 5 1 9 7 0 1 9 7 5 1 9 8 0 1 9 8 5 1 9 9 0 1 9 9 5 2 0 0 0 2 0 0 5 2 0 1 0 2 0 1 5 2 0 2 0 Ye a r S a n t a M o n i c a W e l l N o . 3 S W L M e a s u r e m e n t s S a n t a M o n i c a W e l l N o . 4 S W L M e a s u r e m e n t s S a n t a M o n i c a W e l l N o . 7 S W L M e a s u r e m e n t s Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y Ga g e FI G U R E 1 0 C OL Y M P I C W E L L F I E L D / S U B B A S I N HY D R O G R A P H S D e p t h t o W a t e r L e v e l ( f t b r p ) Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 Accumulated Departure of Rainfall -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 10 20 30 40 50 60 70 80 90 10 0 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 19 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 Ye a r St a t i c W a t e r L e v e l M e a s u r e m e n t Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y G a g e FIGURE 11A KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 5 AR C A D I A S U B B A S I N , T O T A L C H A N G E I N S T O R A G E D e p t h t o W a t e r L e v e l ( f t b r p ) Well Schematic (Depth=ft bgs) No t e : R e f e r e n c e P o i n t = 3 7 8 . 0 8 f t a b o v e m s l 0 ft T.D.=255 ft bgsBlankCasingPerforatedIntervals:145-235 ft bgsAccumulated Rainfall Departure (%) Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 ΔS = - 1 8 f t 29 - y e a r B a s e l i n e P e i o d -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 10 20 30 40 50 60 70 80 90 10 0 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 19 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 Ye a r St a t i c W a t e r L e v e l M e a s u r e m e n t Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y G a g e FIGURE 11B KEY WELL HYDROGRAPH CHARNOCK WELL NO. 16 CH A R N O C K S U B B A S I N , T O T A L C H A N G E I N S T O R A G E D e p t h t o W a t e r L e v e l ( f t b r p ) 0 ft T.D.=410 ft bgsWell Schematic (Depth=ft bgs)Blank Casing Perforated Intervals:220-390 ft bgsPumpat???Pump Column No t e : R e f e r e n c e P o i n t = 1 0 5 . 8 3 f t a b o v e m s l Accumulated Rainfall Departure (%) RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 Δ S = + 3 f t P P= p u m p i n g l e v e l o r i n c o m p l e t e re c o v e r y m e a s u r e m e n t Jo b N o . 4 6 2 - L A S O C July 2017 29 - y e a r B a s e l i n e P e i o d -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 10 20 30 40 50 60 70 80 90 10 0 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 19 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 Ye a r St a t i c W a t e r L e v e l M e a s u r e m e n t s Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y G a g e D e p t h t o W a t e r L e v e l ( f t b r p ) 0 ft T.D.= 564 ft bgsWell Schematic (Depth=ft bgs)Blank Casing Perforated Interval:200-544 ft bgs No t e : R e f e r e n c e P o i n t = 1 5 0 . 4 6 f t a b o v e m s l Accumulated Rainfall Departure (%) RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 ΔS = - 2 6 f t FIGURE 11C KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 7 OL Y M P I C S U B B A S I N , T O T A L C H A N G E I N S T O R A G E P P= p u m p i n g l e v e l o r i n c o m p l e t e re c o v e r y m e a s u r e m e n t P Jo b N o . 4 6 2 - L A S O C July 2017 29 - y e a r B a s e l i n e P e i o d Subbasin Boundary I -4 0 5 I -4 0 5 I -4 0 5I-4 0 5 I -4 0 5I-4 0 5 I -4 0 5 I -4 0 5 I -4 0 5 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y 9 0 F W Y WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T WE S T C O A S T GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N LA X LA X LA X LA X LA X LA X LA X LA X LA X C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n C h a rn o c k S u b b a s i n B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a B a l l o n a C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k C r e e k Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Co a s t a l Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Cr e s t a l Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n Su b b a s i n I-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D HO L L Y W O O D GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N GR O U N D W A T E R B A S I N CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL CENTRAL GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER GROUNDWATER BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN BASIN I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -1 0 I -4 0 5 I -4 0 5 I -4 0 5I-4 0 5 I -4 0 5I-4 0 5 I -4 0 5 I -4 0 5 I -4 0 5 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 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 U T F L O W O F O F O F O F O F O F O F O F O F 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-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 I-10 SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R GR O U N D W A T E R BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA S I N BA 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 O l y m p i c S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n Ar c a d i a S u b b a s i n SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A SA N T A M O N I C A MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S MO U N T A I N S Le g e n d Sa n t a M o n i c a C i t y B o u n d a r y Na m e a n d a p p r o x i m a t e B o u n d a r y o f G r o u n d w a t e r B a s i n (a s d e f i n e d b y D W R B u l l e t i n 1 1 8 U p d a t e 2 0 0 3 ) 14051 Burbank Blvd., Ste. 300, Sherman Oaks, CA 91401 Phone: (818 ) 506-0418 Fax: (818 ) 506-134 3Consulting Groundwater Geologists Richard C. Slade & Associates LLC Date:July 2017Figure 12 Usable Area of Groundwater Storage Subunits Projection: Custom ProjectionAuthor: LAB/JAProject No: 462-LASOC Filename: Figure 12  Wa t e r s h e d B o u n d a r y f o r S a n t a M o n i c a B a y R e g i o n , ar r o w s s h o w g e n e r a l d i r e c t i o n o f s u r f a c e w a t e r r u n o f f (a s d e f i n e d b y T h e C a l i f o r n i a I n t e r a g e n c y W a t e r s h e d M a p o f 1 9 9 9 , u p d a t e d 2 0 0 4 ) Su r f a c e W a t e r O u t f l o w s A l o n g S t r e a m s an d C r e e k s f r o m W a t e r s h e d R e g i o n Ap p r o x i m a t e d F a u l t Z o n e s No t e : F a u l t s a n d s u b b a s i n s w i t h i n S a n t a M o n i c a G r o u n d w a t e r B a s i n n o t s h o w n h e r e o n . Ap p r o x i m a t e U s a b l e S t o r a g e S u b u n i t B o u n d a r y 10 1 Mi l e s -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 10 20 30 40 50 60 70 80 90 10 0 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 19 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 Ye a r St a t i c W a t e r L e v e l M e a s u r e m e n t Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y G a g e FIGURE 13A KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 5 AR C A D I A S U B B A S I N , S P L I T B A S E L I N E P E R I O D D e p t h t o W a t e r L e v e l ( f t b r p ) Well Schematic (Depth=ft bgs) No t e : R e f e r e n c e P o i n t = 3 7 8 . 0 8 f t b e l o w m s l 0 ft T.D.=255 ft bgsBlankCasingPerforatedIntervals:145-235 ft bgsAccumulated Rainfall Departure (%) Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 Δ S = + 3 f t ΔS = - 2 2 f t Pe r i o d o f No P u m p i n g -400.00-300.00-200.00-100.000.00100.00200.00300.00400.00500.00600.00 0 10 20 30 40 50 60 70 80 90 10 0 11 0 12 0 13 0 14 0 15 0 16 0 17 0 18 0 19 0 20 0 19 8 7 1 9 8 8 1 9 8 9 1 9 9 0 1 9 9 1 1 9 9 2 1 9 9 3 1 9 9 4 1 9 9 5 1 9 9 6 1 9 9 7 1 9 9 8 1 9 9 9 2 0 0 0 2 0 0 1 2 0 0 2 2 0 0 3 2 0 0 4 2 0 0 5 2 0 0 6 2 0 0 7 2 0 0 8 2 0 0 9 2 0 1 0 2 0 1 1 2 0 1 2 2 0 1 3 2 0 1 4 2 0 1 5 2 0 1 6 2 0 1 7 Ye a r St a t i c W a t e r L e v e l M e a s u r e m e n t Ac c u m u l a t e d R a i n f a l l D e p a r t u r e - C u l v e r C i t y G a g e FIGURE 13B KEY WELL HYDROGRAPH CHARNOCK WELL NO. 16 CH A R N O C K S U B B A S I N , S P L I T B A S E L I N E P E R I O D D e p t h t o W a t e r L e v e l ( f t b r p ) 0 ft T.D.=410 ft bgsWell Schematic (Depth=ft bgs)Blank Casing Perforated Intervals:220-390 ft bgsPumpat???Pump Column No t e : R e f e r e n c e P o i n t = 1 0 5 . 8 3 f t b e l o w m s l Accumulated Rainfall Departure (%) Jo b N o . 4 6 2 - L A S O C July 2017 RI C H A R D C . S L A D E & A S S O C I A T E S L L C CO N S U L T I N G G R O U N D W A T E R G E O L O G I S T S 14 0 5 1 B u r b a n k B l v d . , S u i t e 3 0 0 Sh e r m a n O a k s , C A 9 1 4 0 1 So u t h e r n C a l i f o r n i a ( 8 1 8 ) 5 0 6 - 0 4 1 8 No r t h e r n C a l i f o r n i a ( 7 0 7 ) 9 6 3 - 3 9 1 4 Δ S = + 2 6 f t ΔS = -80 ft Pe r i o d o f No P u m p i n g APPENDIX 2 TABLES TA B L E 1 SU M M A R Y O F W E L L C O N S T R U C T I O N D A T A FO R E X I S T I N G C I T Y - O W N E D W E L L S We l l No . St a t e We l l N o . St a t e W e l l Co m p l e t i o n Re p o r t N o . (E- l o g D a t e ) Da t e Dr i l l e d Me t h o d of Dr i l l i n g Pi l o t H o l e De p t h (f t ) Ca s i n g T y p e & D e p t h (f t ) Ca s i n g Di a m e t e r (i n ) Bo r e h o l e Di a m e t e r (i n ) Sa n i t a r y Se a l De p t h (ft ) Pe r f o r a t i o n In t e r v a l s (f t ) Type of PerforationsSlot Opening of Perforations (in )Type of Gravel PackCurrent Status Sa n t a Mo n i c a No . 1 1S / 1 5 W - 3 1 E 1 3 1 2 0 8 4 / 6 6 Ca b l e To o l 28 3 S t e e l , 2 5 0 1 4 1 4 N o n e I 5 I - 2 5 0 Moss hydraulic louvers0.158 (5/32")None Active Sa n t a M o n i c a No . 5 ( A K A La M e s a W e l l ) 2S / 1 5 W - 3 0 P 1 09 3 7 8 2 (E - l o g d a t e d 6/ 1 / 8 0 ) 6/ 8 0 Re v e r s e Ci r c u l a t i o n 29 0 S t e e l , 2 5 5 1 4 3 0 5 0 1 4 5 - 2 3 5 l o u v e r s 0.094 (3/32")minus 3/8" Observation Well Sa n t a M o n i c a N o . 6 1 S / 1 5 W - 3 2 E 2 09 3 7 8 1 (E - l o g d a t e d 6/ 1 1 / 8 0 ) 6/ 8 0 Re v e r s e Ci r c u l a t i o n 16 0 S t e e l , 1 4 0 2 0 3 0 5 0 8 0 - 1 2 0 l o u v e r s 0.094 (3/32")3/8" Destroyed in 1908s Ar c a d i a N o . 4 1 S / 1 5 W - 3 2 A 5 9 0 4 4 7 8 / 6 4 Ca b l e To o l 23 5 Or i g i n a l : S t e e l t o 2 3 5 Ca s i n g L i n e r : L o w C a r b o n St e e l t o 2 2 5 14 Li n e r : 1 2 14 n o n e 85 - 2 1 8 Li n e r : 1 1 0 - 2 1 5 Moss hydraulic louvers Liner: wire-wrapped screen0.125 (1/8")Liner: 0.090NoneActive; Casing liner added in 2000 Ar c a d i a N o . 5 1 S / 1 5 W - 3 2 A 6 29 4 1 6 3 E- l o g p e r f o r m e d bu t no t f o u n d 3/ 8 9 Mu d Ro t a r y 25 0 Or i g i n a l : S t e e l , 2 5 0 Ca s i n g L i n e r : L o w C a r b o n St e e l t o 2 3 8 16 Li n e r : 1 2 30 1 2 0 12 2 - 2 2 2 Li n e r : 1 1 0 - 2 3 5 louvers Liner: wire-wrapped screen0.094 (3/32")Liner: 0.090#5 Active; Casing liner added in 2000 (?) Ch a r n o c k N o . 1 3 11 C 1 7 31 2 3 3 9 / 6 6 Di r e c t Ro t a r y 42 3 Or i g i n a l : S t e e l t o 4 1 0 Ca s i n g L i n e r : 3 0 4 L S t a i n l e s s St e e l t o 2 0 0 f t 16 Li n e r : 1 4 No Da t a 49 20 0 - 3 9 0 Li n e r : 1 9 7 - 3 8 8 louvers Liner: wire-wrapped screen0.125 (1/8)Liner: 0.040NDActive; casing liner added in 1991 Ch a r n o c k N o . 1 6 11 C 1 9 09 3 7 8 0 7 / 8 0 Re v e r s e Ci r c u l a t i o n 43 0 St e e l , 4 1 0 20 3 0 1 9 0 2 2 0 - 3 9 0 l o u v e r s 0.094 (3/32)3/8"minus active Ch a r n o c k N o . 1 8 1 1 C 2 2 2 2 9 7 2 0 5 / 8 4 Re v e r s e Ci r c u l a t i o n 48 0 S t e e l , 4 8 0 1 8 3 0 1 0 0 2 4 0 - 4 5 5 wire-wrapped screen 0.050 Monterey 6X12 & 8X16 active Ch a r n o c k N o . 1 9 1 1 C 2 1 2 9 4 1 6 5 1 1 / 8 8 Re v e r s e Ci r c u l a t i o n 55 0 S t e e l , 5 1 0 1 8 3 0 1 5 0 2 0 0 - 4 5 0 l o u v e r s 0.094 (3/32)#5 LG active Ch a r n o c k N o . 2 0 1 1 C 2 3 ( ? ) e 0 1 6 0 8 6 7 9 / 1 2 Re v e r s e Ci r c u l a t i o n 45 0 3 0 4 S t a i n l e s s S t e e l , 4 0 5 1 6 2 6 1 5 0 24 2 - 2 9 5 31 5 - 3 8 5 louvers 0.065 Tacna 6x20 active Sa n t a M o n i c a N o . 3 2 S / 1 5 W - 4 C 2 50 8 1 3 (E - l o g d a t e d 9/ 1 6 / 6 9 ) 10 / 6 9 Re v e r s e Ci r c u l a t i o n 57 0 Or i g i n a l : S t e e l t o 5 5 0 Ca s i n g L i n e r : 3 1 6 L S t a i n l e s s St e e l t o 4 9 8 16 Li n e r 14 t o 2 9 7 12 t o 4 9 8 28 5 0 21 0 - 2 7 0 30 0 - 3 8 0 41 0 - 4 3 0 49 0 - 5 3 0 Li n e r : 2 0 7 - 4 9 8 louvers Liner: wire-wrapped screen0.125 (1/8")Liner: 0.040minus 3/8"Active; Casing liner added in 2014 Sa n t a M o n i c a N o . 4 2 S / 1 5 W - 4 A 1 09 3 7 8 5 (E - l o g d a t e d 12 / 6 / 8 1 ) 12 / 8 1 Re v e r s e Ci r c u l a t i o n 56 0 S t e e l , 5 6 0 2 0 3 2 2 0 0 ( ? ) 20 0 - 4 1 0 47 0 - 5 4 0 louvers 0.094 (3/32")#4 & #5 Active Sa n t a M o n i c a N o . 7 1 S / 1 5 W - 3 0 P 1 21 8 3 3 (E - l o g d a t e d 8/ 2 8 / 8 2 ) 11 / 8 2 Re v e r s e Ci r c u l a t i o n 53 0 S t e e l , 5 6 4 1 6 2 8 1 0 0 2 0 0 - 5 4 4 l o u v e r s 0.094 (3/32")#5 Water Level Observation Well Sa l t W a t e r N o . 1 2 S / 1 5 W - 7 Q 1 4 0 8 5 4 1 1 / 6 7 Re v e r s e Ci r c u l a t i o n 14 0 30 4 S t a i n l e s s S t e e l 12 0 12 2 4 2 0 6 0 - 1 2 0 l o u v e r s 0.125 (1/8")ND Inactive Sa l t W a t e r N o . 2 2 S / 1 5 W - 7 Q 2 ( ? ) LA C F C D # 2 5 3 9 L 50 8 0 2 E- l o g p e r f o r m e d bu t no t f o u n d . 5/ 6 9 Re v e r s e Ci r c u l a t i o n 18 6 30 4 St a i n l e s s S t e e l ( ? ) 12 0 12 ( ? ) N D 2 0 2 0 - 1 2 0 louvers 0.125 (1/8")ND Abandoned Ma r i n e P a r k W e l l 2 S / 1 5 W - 9 N 9 E- l o g p e r f o r m e d bu t n o t a v a i l a b l e 4/ 7 0 Mu d Ro t a r y 18 0 St e e l ( ? ) , 1 5 6 4 ND N D 1 2 5 - 1 3 5 ND ND ND Observation Well Ci t y H a l l W e l l N/ A (E - l o g d a t e d 9/ 2 4 / 1 6 ) 11 / 2 0 1 6 Mu d Ro t a r y 65 2 ba c k f i l l e d t o 1 8 0 ' w i t h 10 . 3 - s a c k c e m e n t PV C 6 1 6 ¼ 5 0 60 - 9 0 12 0 - 1 6 0 slotted screen 0.030 8 X 16, 50'-100'16 X 30,110'-180' Active No t e s : ND = N o d a t a N/ A = d a t a a v a i l a b l e (no t l i s t e d ) o n l o g Ar c a d i a S u b b a s i n Ol y m p i c S u b b a s i n Co a s t a l S u b b a s i n Ch a r n o c k S u b b a s i n *P r i o r t o c o n s t r u c t i o n o f W e l l N o . 2 i n 1 9 4 0 , t h e r e w e r e a t o t a l o f n i n e w e l l s c o n s t r u c t e d a t t h e A r c a d i a p l a n t d a t i n g b a c k t o 1 9 0 3 a n d r e c o r d s f o r t h e s e w e l l s a r e s p a r s e . Sa n t a M o n i c a G r o u n d w a t e r B a s i n S u s t a i n a b l e Y i e l d S t u d y RC S J o b N o . 4 6 2 - L A S O C Ju l y 2 0 1 7 TABLE 2 GROUNDWATER PRODUCTION TOTALS BY CITY WELLFIELDS AND OTHERS (1988 THROUGH 2016) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 ARCADIA CHARNOCK OLYMPIC 1988 372 8,111 387 8,871 1989 357 6,363 457 7,177 1990 389 4,132 469 4,990 1991 417 4,728 387 5,531 1992 396 6,486 981 7,862 1993 390 6,153 2,867 9,409 1994 419 5,906 3,126 9,450 1995 542 6,322 3,176 10,039 1996 370 2,284 3,044 5,697 1997 0 0 2,820 2,820 1998 0 0 2,642 2,642 1999 0 0 2,937 2,937 2000 0 0 2,912 2,912 2001 387 0 2,809 3,196 2002 467 0 1,824 2,291 2003 455 0 593 1,047 2004 137 0 385 522 2005 395 0 1,495 1,890 2006 387 0 1,365 1,752 2007 374 0 1,619 1,993 2008 360 0 1,663 2,023 2009 340 0 1,722 2,062 2010 290 593 2,436 3,320 2011 447 5,168 2,317 7,932 2012 450 5,277 2,636 8,363 2013 434 7,824 1,609 9,867 2014 714 8,377 1,591 10,682 2015 620 8,114 1,961 10,695 2016 698 8,311 1,992 11,001 TOTAL PRODUCTION (Per Basin)10,600 94,100 54,200 159,000 TOTAL AVERAGE PRODUCTION (AFY)*400 5,900 1,900 5,500 RIVIERA GOLF COURSE (TOTAL AF) TOTAL ESTIMATED (AF)*9,000 TOTAL AVERAGE (AFY)310 BRENTWOOD GOLF COURSE (TOTAL AF) TOTAL ESTIMATED (AF)*7,500 TOTAL AVERAGE (AFY)260 AVERAGE ANNUAL EXTRACTIONS (AFY)*1,000 5,900 1,900 9,000 NOTES: NA = Not applicable TOTAL CITY GROUNDWATER PRODUCTION BY SUBBASIN (in AF) YEAR SUBBASIN TOTAL PRODUCTION (Per Year) 1. 2001 groundwater production from Arcadia Wellfield could instead be 353 AF, per email to RCS from Ms. Myriam Cardenas of City of Santa Monica, 1/7/2013 2. City has had no wells in Coastal or Crestal groundwater subbasins of the SMGB * Numbers rounded to nearest 100. For the Arcadia and Charnock subbasins, the average does not include those years for which no pumping was conducted (i.e., zero extraction years). TABLE 3A PRELIMINARY CALCULATIONS OF CHANGE IN GROUNDWATER IN STORAGE DURING BASELINE PERIOD FOR THE ARCADIA, CHARNOCK AND OLYMPIC GROUNDWATER SUBBASINS (METHOD 1 CALCULATIONS) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 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)*-6,100 to -9,100 Average Annual Change in Storage (AFY)-200 to -300 Usable Surface Area of Subbasin (mi2) Estimated Specific Yield of Sediments 12%to 16% 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)*900 to 1,100 Average Annual Change in Storage (AFY)30 to 40 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)*-5,200 to -7,700 Average Annual Change in Storage (AFY)-200 to -300 TOTAL CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*:-10,400 to -15,700 L AVERAGE CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*:-400 to -600 *Numbers rounded to nearest 100 ARCADIA GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 5 (FIGURE 11A) 6.6 130 -26 Note: See text section Titled "Subunit/Subbasin Changes in Groundwater in Storage Calculations", p. 41-46, 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. 148 155 OLYMPIC GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 7 (FIGURE 11C) 144 -18 3.1 CHARNOCK GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH CHARNOCK WELL NO. 16 (FIGURE 11B) 3.7 158 3 118 TABLE 3B PRELIMINARY CALCULATIONS OF CHANGE IN GROUNDWATER IN STORAGE DURING SPLIT BASELINE PERIOD FOR THE ARCADIA, CHARNOCK AND OLYMPIC GROUNDWATER SUBBASINS (METHOD 2 CALCULATIONS) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 Years Only When Pumping was Performed Number of Years When Pumping Was Performed Total Number of Years When Pumping was Performed Usable Surface Area of Subbasin (mi2) Change in Static Water Level for Baseline Period (ft) Static Water Level at Beginning of Period (ft bgs) Static Water Level at End of Period (ft bgs) Change in Static Water Level for Period (ft) Total Change in Static Water Level (Both Periods) Change in Groundwater in Storage in Subunit (AF)* Average Annual Change in Storage (AFY) Years Only When Pumping was Performed Number of Years When Pumping Was Performed Total Number of Years When Pumping was Performed Usable Surface Area of Subbasin (mi2) Estimated Specific Yield of Sediments 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 Static Water Level for Baseline Period (ft) Change in Groundwater in Storage in Subunit (AF)* Average Annual Change in Storage (AFY) TOTAL CHANGE IN STORAGE IN ALL THREE SUBUNITS (in AF)*: Number of Years When Pumping Was Performed Usable Surface Area of Subbasin (mi2) Estimated Specific Yield of Sediments 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)* Average Annual Change in Storage (AFY) TOTAL CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*: TOTAL AVERAGE CHANGE IN STORAGE IN THE THREE SUBUNITS (in AF)*: *Numbers rounded to nearest 100 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. Note: See text section Titled "Subunit/Subbasin Changes in Groundwater in Storage Calculations", p. 41-46, for explanation and derivation of parameters and values. ARCADIA GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 5 (FIGURE 12A) 3.1 118 144 15% -5,200 to -7,700 1988-1996 2001-2006 6.6 29 9 16 25 CHARNOCK GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH CHARNOCK WELL NO. 16 (FIGURE 12B) -300 -400to 133 8%12% 127 148 to 130 -9,600to -22 -19 OLYMPIC GROUNDWATER STORAGE SUBUNIT - KEY WELL HYDROGRAPH SANTA MONICA WELL NO. 7 (FIGURE 11C) 158 75 132 155 26 -80 -54 -15,300 to -20,500 -6,400 3 16 3.7 12%to 16% 9 7 1988-1996 2010-2016 -1,500 -2,000to -1,000 to -1,300 -6,500 -9,400 1988-2016 to to -200 -300 -26 10%to TABLE 4A PRELIMINARY CALCULATIONS OF SUSTAINABLE YIELD THREE SANTA MONICA SUBBASINS (METHOD 1 CALCULATIONS) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 SUBBASIN AVERAGE ANNUAL EXTRACTIONS FOR BASELINE PERIOD (AFY)* Arcadia -200 to -300 1,000 700 to 800 Charnock 30 to 40 5,900 5,930 to 5,940 Olympic -200 to -300 1,900 1,600 to 1,700 TOTALS*:-400 to -600 8,800 8,230 to 8,440 Note: BASELINE PERIOD AVERAGE ANNUAL CHANGE IN STORAGE (ΔS in AFY) 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 100 TABLE 4B PRELIMINARY CALCULATIONS OF SUSTAINABLE YIELD TWO SANTA MONICA SUBBASINS (METHOD 2 CALCULATIONS) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 SUBBASIN AVERAGE ANNUAL EXTRACTIONS FOR BASELINE PERIOD (AFY)* Arcadia -300 to -400 1,000 600 to 700 Charnock -1,000 to -1,300 5,900 4,600 to 4,900 TOTALS*:-1,300 to -1,700 6,900 5,200 to 5,600 Note:City has no wells in Crestal or Coastal subbasins and, thus, these subbasins are not considered herein. BASELINE PERIOD AVERAGE ANNUAL CHANGE IN STORAGE (ΔS in AFY)* RANGE OF SUSTAINABLE YIELD (AFY)* *Numbers rounded to nearest 100 TABLE 5 COMPARISON OF SUSTAINABLE YIELD VALUES SANTA MONICA SUBBASINS (USING METHODS 1 and 2) Santa Monica Groundwater Basin Sustainable Yield Study RCS Job No. 462-LASOC July 2017 GROUNDWATER SUBBASIN PREVIOUS STUDIES (AFY) Arcadia(1)600 to 800 2000 (2, 3) Charnock 4,600 to 5,930 4,420 to 7,500(4) and 8,200(5) Olympic 1,600 to 1,700 3,275(3) TOTALS:6,800 to 8,430 9,695 to 13,475 Coastal 4,225(3) Crestal 2,000(6) TBD = To Be Determined. 3) RCS March 27, 2013 6) This is the midpoint value of the LADWP (1991) 4) From KJC, June 1992, for the combined Arcadia, Olympic & Charnock subbasins. 5) From Komex, 2001. The value derived by Komex was accepted by RCS in its March 2013 M 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 CURRENT STUDY (AFY) TBD Notes/Sources of the numbers: TBD 1642 E. Fourth Street  Santa Ana  California  92701  USA Telephones: 714-412-2654 & 544-5321  Facsimile: 714-494-4930  www.earthconsultants.com ECI Project No. 3615 September 15, 2017 To: City of Santa Monica Water Resources Protections Programs 1212 5th Street, 3rd Floor Santa Monica, California 90401 Attention: Mr. Thomas L. Watson, PG Water Resources Protection Programs Coordinator Subject: Report – 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 (ECI) are pleased to present this report describing the scope of work, methodology, findings and conclusions of a baseline study we conducted at your request and per your authorization for the Santa Monica Groundwater Basin (SMGB) region using Differential Satellite Interferometry (DInSAR). The purpose of this baseline study was to assess whether the rise and drop of the water levels in the aquifers in the SMGB area manifest at the surface as uplift and subsidence, respectively. We used DInSAR as the detection tool, given that this cost-effective method has a proven record of showing ground surface deformation associated with groundwater extractions and recharge under favorable circumstances in several other groundwater basins throughout the Western United States. As part of this study we downloaded, processed and analyzed dozens of SAR images dating from 1992 (when these satellite-based images were first collected) through 2016. In total, we generated 47 interferograms spanning the time period of interest, with this number dictated by the availability and quality of the radar images. Three of these interferograms covered the period between 1992 and 1996, a period when the City was pumping extensively from the aquifers, before the discovery of volatile organic carbons (VOCs) in the groundwater prompted the temporary cessation of pumping and/or minimized extractions within selected wellfields in the SMGB. This time period also spanned the 1994 Northridge earthquake, and we used the ground deformations associated with that tectonic event as a measure of the effectiveness of DInSAR to detect vertical movements in the region. Thirty-three of the interferograms we prepared covered the period between 1996 and 2010, when groundwater extraction from the basin was minimal, in an effort to observe potential land surface rebound while natural recharge continued. Finally, eleven interferograms covered the time period between 2010 and 2016, after pumping began again. The interferograms analyzed for this study show very little surface deformation occurring in the study area in the period between 1992 and 2016, and any correlations between the surface ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Cover Letter - Page 2 deformations observed and changes in the water level of the underlying water-producing aquifer are not statistically significant. The interferogram produced from SAR images from 1992 and 1996, which span the 1994 Northridge earthquake, shows ground deformation in the epicentral area at a scale in close agreement with survey-derived measurements of uplift. This in turn indicates that the interferograms generated for this study were properly processed and thus, that the lack of appreciable surface deformation indicated by the data is truly representative of the study area during the period covered by the analysis. We conclude from these analyses that the fine-grained, compressible layers in the aquifer are not responding to changes in the water level resulting from extractions and recharge. We postulate that the reason for this is that these strata were irreversibly compacted due to excessive pumping in the 1930s and 1940s, when the water levels in the aquifer were several tens of feet lower than the levels measured between 1992 and 2016. If future groundwater extractions in the SMGB cause the water levels to drop to or below the 1930-1940 levels, it is possible that the SMGB area could experience subsidence at levels detectable by the InSAR method. For this reason, we recommend continued monitoring of the SMGB region using DInSAR, augmented with several permanent, automated GPS monitoring stations. We hope that the information presented in the following report provides you with the data you need at this time. We appreciate the opportunity to provide these services to the City of Santa Monica. Should you have any questions regarding the above, please do not hesitate to contact us at your earliest convenience. Respectfully submitted, EARTH CONSULTANTS INTERNATIONAL, INC. Registered Geologists, Certified Engineering Geologists and Certified Hydrogeologists Anders Hogrelius Eric Hendrix, CHg 431, CEG 1531 Project Consultant Senior Project Consultant Tania Gonzalez, CEG 1859 Vice-President ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Table of Contents – Page i TABLE of CONTENTS Section Page No. 1.0 INTRODUCTION .............................................................................................................. 1 1.1 Purpose of the Study .......................................................................................................... 1 1.2 Regulatory and Practical Framework Guiding the Study ..................................................... 1 2.0 TECHNICAL BACKGROUND ............................................................................................ 2 2.1 Differential Interferometry Synthetic Aperture Radar (DInSAR) ........................................... 2 2.2 Ground Deformation Resulting From Groundwater Extractions .......................................... 3 2.3 Hydrogeologic Framework of the Santa Monica Groundwater Basin .................................. 4 2.3.1 Subbasins of the Santa Monica Groundwater Basin ................................................................ 6 3.0 WORK COMPLETED AND METHODOLOGY FOLLOWED ............................................... 7 4.0 FINDINGS AND DISCUSSION ......................................................................................... 9 4.1 Basin Key Wells and Extraction Centers ............................................................................. 9 4.2 DInSAR Results ................................................................................................................ 11 4.3 Correlation Between Interferograms and Key Well Data ................................................... 11 4.4 Other Sources of Ground Deformation in the Target Area ................................................ 13 5.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................ 13 5.1 Conclusions ..................................................................................................................... 13 5.2 Recommendations ........................................................................................................... 13 6.0 REFERENCES AND SOURCES .......................................................................................... 15 TABLES (in the back) Table 1: Santa Monica Groundwater Basin Production History FIGURES and PLATE (in the back) Figure 1: Site Location Map Figure 2: Santa Monica Groundwater Basin, Subbasins and Well Locations Figure 3: Well Schematics and Stratigraphic Profile, Historical Water Depth, Rainfall, Groundwater Production and Surface Deformation for Charnock Well No. 16 Figure 4: Well Schematics and Stratigraphic Profile, Historical Water Depth, Rainfall, Groundwater Production and Surface Deformation for Santa Monica Well No. 3 Figure 5: Well Schematics and Stratigraphic Profile, Historical Water Depth, Rainfall, Groundwater Production and Surface Deformation for Arcadia Well No. 4 Figure 6: Well Schematics and Stratigraphic Profile, Historical Water Depth, Rainfall, Groundwater Production and Surface Deformation for Santa Monica Well No. 1 Figure 7: Composite Hydrograph for the Charnock Subbasin Comparing Pre-SAR-Era and SAR-Era Water Levels ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Table of Contents - Page ii Figure 8: Composite Hydrograph for the Arcadia Subbasin Comparing Pre-SAR-Era and SAR-Era Water Levels Figure 9: Hydrograph for the Olympic Subbasin (Santa Monica Well No. 3) Comparing Pre-SAR- Era and SAR-Era Water Levels Plate 1: Surface Deformation and Hydrologic Data at Pumping Centers, Santa Monica Groundwater Basin APPENDICES Appendix A: Additional Technical Information Regarding the DInSAR Method and Statistical Analyses Completed as Part of This Study Appendix B: Interferograms Analyzed Appendix C: Logs of Key Wells, Santa Monica Groundwater Basin ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 1 BASELINE STUDY TO EVALUATE THE EFFECTIVENESS OF DIFFERENTIAL INTERFEROMETRY SYNTHETIC APERTURE RADAR (DInSAR) TO IDENTIFY LONG-TERM LAND ELEVATION CHANGES RELATED TO GROUNDWATER EXTRACTIONS FOR THE SANTA MONICA BASIN 1.0 INTRODUCTION 1.1 PURPOSE OF THE STUDY At the request of the City of Santa Monica (City), Earth Consultants International (ECI) conducted a initial baseline study for the Santa Monica Groundwater Basin (SMGB) area using satellite-based Differential Interferometry Synthetic Aperture Radar (DInSAR). The purpose of the study was to evaluate whether land surface elevation changes in the form of negative deformation (subsidence) were discernible between 1992 and 2016 in the area overlying the SMGB or its subbasins (Figures 1 and 2). Subsidence of the ground surface in groundwater basins is typically the result of unsustainable groundwater withdrawals, and can, over time, affect aquifer characteristics by the irreversible compaction of sediments in the subsurface. A second-phase investigation will assess for the potential to discern inflow of natural recharge into the SMGB. 1.2 REGULATORY AND PRACTICAL FRAMEWORK GUIDING THE STUDY The SMGB is currently not adjudicated. In 2014, the State passed the California Sustainable Groundwater Management Act (SGMA), a piece of legislation comprised of three separate bills, including Assembly Bill 1739, Senate Bill 1319, and Senate Bill 1168 (California Department of Water Resources - CDWR, 2015). The SGMA, which went into effect on January 1, 2015, requires the formation of local Groundwater Sustainability Agencies (GSAs) whose role is to monitor and ensure that groundwater resources in the State are used and managed sustainably. As a result of the drought that California experienced during 2010 through 2016, and the increasingly larger number of water supply users, including agricultural, industrial, commercial and residential interests, many of the groundwater basins in central and southern California have been and are being mined (pumped) in excess of their natural rate of replenishment, with a resultant drop in the groundwater table. In some areas this in turn has led to compaction of the geologic sediments and significant land subsidence, with a concomitant damage to utilities, public infrastructure, and other natural resources such as groundwater-fed streams and springs. Senate Bill 1168 requires, among other things, the GSAs regularly measure and monitor the depth to groundwater in their basin, and calculate the maximum amount of water that can be pumped out of the basin in a year without causing an “undesirable result.” This amount of groundwater is referred to as “the sustainable yield.” An “undesirable result” can include any of the following: 1) chronic or persistent lowering of the groundwater level, 2) significant and unreasonable reduction in groundwater storage, 3) significant and unreasonable seawater intrusion, 4) significant and unreasonable degradation of water quality, 5) significant and unreasonable land subsidence, and 6) depletions of surface water that result in significant and unreasonable adverse impacts on beneficial uses (Water Education Foundation, 2015). Because groundwater is a resource not directly observable, the monitoring for any of these conditions is not particularly straightforward. Monitoring of available groundwater in storage is strongly contingent upon measurements of the static water levels in a network of piezometers and wells installed into the aquifers. This is readily done in existing wells, but in densely urbanized areas, such as Santa Monica, it is difficult to ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 2 add new monitoring stations in strategic places. However, because the lowering of the groundwater level and the reduction in groundwater storage is often accompanied by a lowering of the ground surface (subsidence), a method that has proven useful in some areas is to correlate the deformation of the ground surface to the rise or fall of the water level in the underlying aquifer(s). Some of the regions where this method has been used successfully include California's Central Valley, the Main Aquifer in the Orange County Groundwater Basin, and areas around Las Vegas, Nevada (Borchers et al., 2014). Furthermore, monitoring of ground deformation can help inform how planned groundwater extractions might impact a region, particularly in areas such as the City of Santa Monica, where future water use projections may possibly exceed the available groundwater supply and sustainable yield of the SMGB (Kennedy/Jenks Consultants - KJC, 2015; Richard Slade & Associates - RSA, 2017). Traditionally, the monitoring of ground surface deformation has been conducted using spirit- leveling (surveying) techniques. This method is very precise but time-consuming, and spatially and temporally sparse, as measurements are made at relatively few locations, and at temporal intervals typically measured in months or years (e.g., Poland et al., 1984). Other techniques that are used include a network of Global Positioning System (GPS) surveys, permanent continuous GPS measurements, and DInSAR. DInSAR has been used for more than 20 years by government agencies and research institutions to assess the conditions of topographic elevation changes, to monitor groundwater basins in order to quantify potential sediment consolidation, and to monitor surface deformation resulting from the extraction and/or recharge of groundwater (for a few examples of these studies, refer to the links provided in the References section of this report). Compared with the other direct-measurement methods briefly described above, DInSAR is considered more effective, as this method maps both the magnitude of the vertical deformation and the spatial distribution of the affected areas (i.e., it is sensitive to changes in land elevation and can cover large regional areas). Provided a relatively suitable number of satellite passes are available, DInSAR can also yield measurements over relatively short periods of time. Finally, relatively recent developments in the processing of interferograms to provide time-series analyses of the deformation have further increased the potential value of DInSAR as a tool for the monitoring of aquifers. The level of detail and broad areal coverage that DInSAR can provide makes it a potentially valuable tool for local GSAs looking to adopt sustainable management plans in response to the requirements of the California Sustainable Groundwater Management Act (SGMA) of 2014. 2.0 TECHNICAL BACKGROUND 2.1 DIFFERENTIAL INTERFEROMETRY SYNTHETIC APERTURE RADAR (DInSAR) The DInSAR method relies on the processing and comparison of two Synthetic Aperture Radar (SAR) images of the same portion of the Earth’s surface taken by the same satellite system on two different passes. The product resulting from the digital comparison of the two SAR images is called an interferogram; the resulting image illustrates and quantifies the changes in the ground surface that occurred between the two satellite passes used in the analysis. The method can detect vertical changes of the ground surface of as little as 5 millimeters (0.2 inch) for standalone interferograms, and changes below 5 millimeters (limit depending on the wavelength of the radar) when multiple interferograms are used together with a stacking algorithm. The commercially available SAR ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 3 images from the satellite platforms that we used for this study (discussed further below) have a pixel resolution of 25 meters (~82 feet) with no space between pixels. As of April 2017, when the analysis for this study was conducted, archived satellite data from four different satellite systems were available for the past 24 years (1992 to 2016), as follows: 1. European ERS-1 and ERS-2 satellites for the years between 1992 and 2000 (the first SAR images were taken in 1992, thus this is the earliest possible application of this technology), 2. Japanese ALOS and European ENVISAT satellites for 2000 to 2012, and 3. European Sentinel satellites for the period after 2012. Data from all satellite systems are available through the European Space Agency (ESA) and the Japanese Space Agency (JAXA). A radar image generated by one of these satellites cannot be directly compared to an image generated by another satellite system, so the interferograms that are generated have to be based on images from the same system. The interferograms generated, however, can be compared across satellite platforms. Interferometric patterns that may result from the comparison of two or more paired radar images from different time periods may be used to interpret subsurface structures defining the margins of aquifers, as well as internal structures and stratigraphy, especially when combined with data from other sources like groundwater extraction records, water level data and well logs. Once a baseline is established and calibrated, yearly, biannual or quarterly interferograms can be used as a cost- effective management tool for monitoring the conditions of the basins. Additional information on DInSAR, including the methodology used to process the data, is provided in Section 3.1 and Appendix A. 2.2 GROUND DEFORMATION RESULTING FROM GROUNDWATER EXTRACTIONS In California, land subsidence primarily occurs as a result of groundwater extraction, but can also result from tectonic (mountain forming and seismic) activity, natural consolidation of sediment, oxidation and compaction of organic deposits, hydrocompaction of moisture-deficient soil and sediments, and extraction of hydrocarbons (Poland et al., 1984; Galloway and Burbey, 2011; Borchers et al., 2014). Aquifer systems experience some degree of deformation in response to changes in hydraulic stress, which include additions such as natural (rainfall) recharge and/or artificial recharge, or withdrawals such as groundwater pumping or reinjection (Galloway and Burbey, 2011; Bawden, 2003). The seasonal cycle of discharge and recharge from unconsolidated heterogeneous aquifer systems, such as those underlying many locations in the Central, San Joaquin, Santa Clara and Antelope valleys, typically causes measurable elastic (recoverable) land subsidence and proportionate uplift (measured in millimeters to centimeters) of the land surface. Removing water from storage in fine-grained sediments (silts and clays) interbedded in the aquifer system can cause these highly compressible sediments to compact inelastically and permanently as pore pressure is reduced. Land subsidence from inelastic (non-recoverable) compaction is a common consequence of significant groundwater level changes that can result from development of groundwater as a resource (Borchers et al., 2014; Sneed, 2016). ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 4 There are some limitations to the use of ground surface deformation when monitoring aquifers. Specifically, for surface deformation to occur, there must be one or more compressible layers of sufficient thickness under static conditions below the top of the saturated zone, and this layer (or layers) needs to have been dewatered during extended periods of continuous pumping. Reversible (elastic) surface deformation may occur as the pore pressure within the compressible layers cyclically rises and falls during either seasonal or other forms of alternating short-period extractions and recharge. Alternatively, if the compressible layers are dewatered due to pumping without significant recharge for an extended period of time (i.e., several years), irreversible (inelastic) surface deformation will typically occur (Bawden, 2003; Borchers et al., 2014; Orange County Water District, 2015). Monitoring of surface deformation is thus primarily a useful tool if 1) the aquifers in question contain suitable compressible layers, and 2) those layers have not been previously dewatered for an extended period of time below a depth termed the “pre-consolidation stress” (e.g., prior historical low water level). 2.3 HYDROGEOLOGIC FRAMEWORK OF THE SANTA MONICA GROUNDWATER BASIN The Santa Monica Groundwater Basin (SMGB; see Figures 1 and 2) encompasses an area of roughly 50 square miles. The City of Santa Monica is the only purveyor in the Santa Monica Basin actively producing groundwater (KJC, 2015). Physiographically and hydrologically, the SMGB is adjacent to the Santa Monica Mountains watershed to the north, the Pacific Ocean to the west, the Hollywood Basin to the northeast, the Central Groundwater Basin to the southeast, and the West Coast Basin to the south. In addition to the City of Santa Monica, cities overlying the SMGB include Culver City and Beverly Hills, and the City of Los Angeles communities of Pacific Palisades, Brentwood, Venice, Marina del Rey, West Los Angeles, Century City, and Mar Vista. Groundwater recharge within the SMGB is believed to occur primarily by percolating rainfall across the basin and by surface runoff from the adjacent Santa Monica Mountains. According to available records, the City conducted limited subsurface injection of imported Metropolitan Water District (MWD) water via its wells at the Charnock wellfield for a period of approximately 13 years (between 1975 and 1988). Because of the degree of urbanization within the City and the surrounding SMGB areas, there appears to be insufficient land area to conduct future artificial recharge through the construction of spreading basins at the ground surface. Indeed, the City historically has never conducted any artificial recharge operations using spreading basins. However, the City is considering artificial recharge through recharge wells as part of its planned Sustainable Water Infrastructure Project (SWIP) in order to increase its drought resiliency and water sustainability. Present-day groundwater flow patterns are primarily southerly through all five subbasins of the SMGB, with eventual discharge towards the Ballona Gap (Figure 2), and then west towards the Pacific Ocean. Local flow-direction deviations occur towards the City’s three main pumping water supply wellfields within the Charnock, Olympic and Arcadia subbasins. The geology of the SMGB consists of unconsolidated and semi-consolidated fluvial and marine deposits (Poland et al., 1959; CDWR, 1961; Yerkes et al., 1965; Reichard et al., 2003). Primary fresh-water-producing units include the heterogeneous but primarily coarse-grained sediments of the Holocene alluvium, heterogeneous alluvial and shallow marine sediments of the Upper Pleistocene Lakewood Formation, and the ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 5 heterogeneous but chiefly coarse-grained deltaic deposits of the Lower Pleistocene San Pedro Formation. Holocene alluvium in the SGMB reaches a maximum thickness of approximately 90 feet and includes silts and clays of the Bellflower Aquiclude and the underlying Ballona Aquifer (also referred to as the “50-Foot Gravel”). The Ballona Aquifer was formed during the last sea-level low stand by a system of stream channels that eroded through elevated, older sediments to reach the new base level, resulting in the present Ballona Gap geomorphology at the southern edge of the SMGB. As sea level began to rise at the end of the Pleistocene and early Holocene, the carved channels were backfilled with alluvial sediments, forming the deposit known as the “50-Foot Gravel” or Ballona Aquifer. Within the southern portion of the SMGB, the "50-Foot Gravel" is generally separated from the underlying San Pedro Formation by a fine-grained confining layer (aquiclude); locally, however, the two stratigraphic units are in direct contact. The Lakewood Formation appears to be present primarily in the northern portion of the SMGB. Some of the City’s wells in the Arcadia and Olympic subbasins are interpreted to be screened across aquifers within both the Lakewood and San Pedro formations (KJC, 2011; RSA, 2013). Where the Lakewood Formation is present, its lower fine-grained member typically forms a leaky aquiclude above the deeper Silverado Aquifer (Reichard et al., 2003; GeoTrans, 2005; ICF, 2015). The most important water-bearing strata throughout the SMGB are typically the sands and gravels within the Silverado Aquifer in the upper San Pedro Formation (Poland et al., 1959; CDWR, 1961; RSA, 2013). The San Pedro Formation averages about 200 feet in thickness in the SMGB. The estimated transmissivity of the Silverado Aquifer within the study area ranges between 50,000 and 150,000 gallons per day per foot (gpd/ft) (CDWR, 1961; RSA, 2015, 2017a). Specific yield of this aquifer is estimated at up to 26 percent (CDWR, 1961). Constant-rate pumping tests performed within wells screening the Silverado Aquifer indicate an average storativity value of 0.02. These measurements confirm the semi-confined nature of the Silverado Aquifer, and the leaky nature of the overlying Lakewood aquiclude (GeoTrans, 2005; ICF, 2015). Beneath the Silverado Aquifer are generally low-permeability sediments of the lower San Pedro and upper Pico formations. The Newport-Inglewood Fault Zone, a known barrier to deep groundwater flow, forms the eastern boundary of the SMGB, whereas the Ballona Gap or Escarpment (an erosional feature) comprises its southern boundary (CDWR, 1961; KJC, 2011; RSA, 2013). Internally, several other faults are believed to impact groundwater storage and flow sufficiently to merit the partitioning of the SMGB into five separate subbasins (KJC, 2011; RSA, 2013) (Figure 2). These faults include the north- to northwest-trending Charnock and Overland Avenue faults, and the complex east- to east- northeast-trending Santa Monica Fault Zone (SMFZ). The SMFZ includes multiple en echelon and branching segments such as the Potrero Canyon fault near the coast (labeled the Brentwood fault on Figure 2 herein, after RSA, 2013), as well as other segments farther inland. The SMFZ was recently zoned under the criteria of the Alquist-Priolo Earthquake Fault Zoning Act (California Geological Survey, 2017; Olson, 2017), and is considered a Holocene-active fault (i.e., sections of the fault are interpreted to have moved at least once in the past 11,700 years). The Charnock and Overland Avenue faults are currently considered not active, as they do not appear to offset Holocene-age sediments, but additional studies are required to confirm this. Whether classified as active or not active, each of these faults has at least several tens of feet of vertical displacement, and thus has the ability to impact ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 6 groundwater flow. The fault-bounded subbasins that comprise the SMGB include the Charnock, Coastal, Crestal, Arcadia, and Olympic. These subbasins are discussed further in the subsection below. 2.3.1 Subbasins of the Santa Monica Groundwater Basin The Charnock subbasin is separated from the Coastal subbasin by the Charnock fault, and from the Crestal subbasin by the Overland Avenue fault (Figure 2). The Charnock subbasin has moved down relative to the Coastal subbasin to the west and the Crestal subbasin to the east across these faults. Therefore, the aquifers in the Charnock subbasin occur at a lower elevation and are notably thicker and more transmissive than those in either of the adjoining subbasins. This is the primary reason why the Charnock subbasin has the greatest historical productivity of all areas of the SMGB (see Table 1). Prior to 1980, groundwater elevations within wells in the Charnock subbasin (see Figure 3; Charnock Well No. 16 hydrograph) were between 30 and 40 feet below sea level. Between 1980 and 1995, groundwater levels rose, but were still below sea level. In 1996, City groundwater production ceased in this subbasin due to third party VOC contamination, and groundwater levels resultantly rose to roughly 10 feet above mean sea level in all subbasin wells over the approximately 13 years the field was shut down. Because of its historically low groundwater levels, regional SMGB groundwater flow has been directed towards the Charnock subbasin from adjoining areas. The fault boundaries of the Charnock subbasin behave as partial hydrologic barriers (general flux boundaries) with respect to groundwater flow through the San Pedro Formation, but do not appear to significantly affect flow within the overlying younger strata (Reichard et al., 2003; GeoTrans, 2005). The Olympic subbasin, as historically defined, lies between segments of Santa Monica Fault Zone (Figure 2). Displacement on these various segments appears to be generally down toward the south with commensurate southward groundwater flow within the Silverado Aquifer. However, local reversals of this trend have been observed or interpreted in some areas, such as within monitoring wells at the City Maintenance Yard (ICF, 2015), along the boundary between the southern Olympic subbasin and the Coastal subbasin. In general, the aquifers in the Arcadia subbasin to the north sit at higher elevations than those in the Olympic subbasin. As a result, groundwater levels in wells of the Olympic subbasin are generally lower than those in the Arcadia subbasin (compare the hydrograph for Santa Monica Well No. 3 in the Olympic subbasin [Figure 4] with that for Santa Monica Well No. 1 in the Arcadia subbasin [Figure 6]). The hydrograph for Well No. 3 suggests some hydraulic connectivity with the Charnock subbasin (GeoTrans, 2005; RSA, 2013), despite the presence of the Charnock fault as a partial flow barrier. The recent revisions to the locations of segments of the Santa Monica fault (Olson, 2017) might have some impact on the Olympic subbasin boundaries, groundwater in storage, groundwater flow and/or sustainable yield estimates. The Arcadia subbasin is bordered by the Santa Monica Mountains to the north and the northern segments of the Santa Monica Fault Zone (names vary) to the south, at the boundary with the Olympic subbasin. Because of this configuration, the Arcadia subbasin receives significant ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 7 groundwater recharge and surface runoff from the Santa Monica Mountains, which contribute to groundwater levels in the Arcadia subbasin wells being the highest in the entire SMGB (see Figures 5 and 6). In particular, the Santa Monica Well No. 1 hydrograph (Figure 6) shows that historic groundwater levels were more than 200 feet above sea level during the 1960s and 1970s (RSA, 2013). Historically, groundwater flow from the Arcadia subbasin into the Charnock and Olympic subbasins has been considered an important component of groundwater recharge into these subbasins. 3.0 WORK COMPLETED AND METHODOLOGY FOLLOWED Pursuant to our proposal dated September 1, 2016, ECI completed the tasks outlined below as part of this study. Where appropriate, specifics regarding the methodology followed are also summarized. A more detailed description of the DInSAR method is provided in Section 2.1 and in Appendix A. 1. Located suitable SAR image data from ESA’s and JAXA’s archives (ERS-1 and ERS-2, ENVISAT, and Sentinel-1 satellite databases), with the suitability of the data determined by date and/or season, and similarity in the path of the satellite passes (we looked for radar images acquired from orbits in the same direction and a Baseline Perpendicular Offset [BPerp] of less than 100 meters between the orbits of the satellites). To that end, we obtained several paired sets of images from each of the time periods of interest to generate the interferograms used in this study, with the final number of interferograms analyzed determined by the availability and quality of the radar images. We also acquired a reference (10-meter) Digital Elevation Model (DEM) for the target area available from the U.S. Geological Survey (USGS). This DEM was used to process the interferograms. 2. Processed the SAR image data and generated differential interferograms (DInSARs) either using pairs of SAR images, or with one master and two or more slave images, to generate a detailed map of the surface deformation (uplift and/or subsidence) that may have occurred during the time period considered. The processing was conducted using the software package GMTSAR. The interferograms generated are as follows:  For the period between 1992 and 1996, three (3) interferograms were used to evaluate changes in the surface elevations during “normal” groundwater pumping conditions (i.e., before 1996, when Volatile Organic Carbons [VOCs] prevented the use of water from the Arcadia and Charnock wellfields in the City). As discussed above, these satellite data first became available in 1992, hence the start-up date for the time period covered in this analysis.  For the period between 1996 and 2010, thirty-three (33) interferograms were generated to obtain information on potential land surface rebound when pumping was minimal.  For the period between 2010 and 2016, eleven (11) interferograms were generated to obtain data on potential surface deformation caused by increased water extraction by the City of Santa Monica, which began in 2010. 3. Once the interferograms were generated, we converted their units from phase shift to absolute elevation change (in millimeters, see Figures 3 through 6), to evaluate whether or not areas in the study region have experienced subsidence or uplift. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 8 4. Performed a review of historical groundwater extraction data provided to us by the City, Richard Slade & Associates (RSA), and ICF International (ICF) to establish groundwater level trends for all periods analyzed using DInSAR. Various parties and consultants to the City of Santa Monica have collected water level measurements regularly in all pumping wellfields since 1975. We also obtained local precipitation data from the National Oceanic and Atmospheric Administration (NOAA) and other sources. All of these data for each of the areas analyzed are presented in graphical form on Figures 3 through 6, and on Plate 1. 5. Compared the completed interferograms to the groundwater data to determine whether or not the land elevation changes imaged by the interferograms appear to be temporally and/or spatially associated with changes in water pumping or recharge over time. Three tests were done with the individual interferograms to: 1) identify aquifer boundaries, 2) identify active tectonic movements that potentially can harm utilities and infrastructure, and 3) detect areas where uplift or subsidence that may be related to variations in the water levels in the aquifers has occurred during the time period considered for this study. The first test was to visually inspect the interferograms for any sharp changes in deformation within the target area. The second test was to use GIS tools to generate a number of profiles to detect changes and gradients in the deformation rate that are too weak to be detected with the naked eye. The third test was to extract point deformation data for key well locations and look for statistic correlations between any detected deformation and the well hydrographs. Specifically, point deformation data were extracted for the various pumping well locations, and compared with selected “key well” water-level hydrographs, well logs, rainfall records and groundwater production data provided to us by the City. Horizontal profiles were also extracted from both individual and stacked interferograms to search for surface deformation related to known pumping depressions in City well fields, as well as the faults that act as boundaries, impacting groundwater movement across the basin. Statistical analyses were run on the data to evaluate whether or not there is a correlation between the DInSAR and groundwater data. Details of these analyses and the results are included in Appendix A, and examples of the interferograms developed are included in Appendix B. All of the interferograms processed for this study are also included in the attached compact disk. 6. To evaluate further whether any areas undergoing deformation (subsidence) are in fact responding to dewatering of the underlying aquifers, we analyzed available water-well logs to identify saturated fine-grained stratigraphic horizons that could experience a reasonable magnitude of compaction during pumping-dewatering cycles. Copies of the water well logs used for this analysis are included in Appendix C. 7. Prepared this report and accompanying illustrations describing the work completed, and presenting our findings, conclusions and recommendations. We also prepared monthly progress reports and met with you to discuss our findings. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 9 4.0 FINDINGS AND DISCUSSION 4.1 BASIN KEY WELLS AND EXTRACTION CENTERS Owing to the close spatial distribution of most City pumping wells which have historically produced localized and discrete pumping depressions, ECI opted to rely on the concept of “Key Wells” for comparison to potential surface deformation in these discrete zones. For consistency with previous and on-going groundwater studies in the SMGB, these key wells are similar to those identified by other consultants to the City of Santa Monica (RSA, 2013; 2017a), and are considered representative of the hydrogeologic conditions and production histories in those discrete areas of extraction and, by extension, any potential related ground surface deformations. Four Key Wells were utilized for this study; their selection was based in large part on the groundwater extraction histories of four critical subbasin areas of the SMGB (Figure 2). These Key Wells include Charnock subbasin well No. 16, Olympic Subbasin Santa Monica well No. 3, Arcadia subbasin well No. 4, and Arcadia subbasin Santa Monica well No. 1. Table 1 summarizes SMGB production history for each of these three subbasins from 1975 onwards, based on data provided to us by the City that includes the time period of available SAR images for this analysis. Pre-1975 extractions from the SMGB are also available, but production totals are not distinguished for individual pumping centers or subbasins (RSA, 2013). As discussed above, the City’s active SMGB pumping centers are located only within three distinct areas, namely the Charnock, Arcadia, and Olympic subbasins. The quantity and quality of the groundwater within those portions of the Coastal subbasin that lie within the boundaries of the City are unknown as the City does not pump from this subbasin. The Crestal subbasin has reportedly had minimal production between 1975 and 2016, chiefly from small private irrigation wells at local country clubs (KJC, 2011, 2015). The City of Santa Monica has extracted groundwater from the SMGB since 1924; cumulative groundwater extractions increased steadily to 6,969 acre-feet (AF) in 1940. In 1941, the City began receiving imported water deliveries from the Metropolitan Water District (MWD). During the late 1940s groundwater use was gradually discontinued, but by 1954 the City once again began to gradually utilize more groundwater as development and population increased and available annual MWD entitlements diminished. This trend continued through 1996, when third-party VOC contamination was discovered in both the Charnock and Arcadia subbasins, and selected wells were shut down as a result. The Charnock Wellfield has historically been the most productive in the SMGB, and has five active groundwater wells (Figure 2), including Charnock No. 13, Charnock No. 15, Key Well Charnock No. 16 (Figure 3), Charnock No. 18, and Charnock No. 19. These wells have a reported combined capacity of approximately 9,000 acre-feet per year (AFY) (KJC, 2011, 2015). However, this production rate is not considered to be viable as it exceeds the estimated sustainable yield (RSA, 2017a) from the Charnock subbasin (estimated at approximately 5,900 AFY). The Arcadia Wellfield has two active production wells: Key Well Arcadia No. 4 and Arcadia No. 5 (Figure 2). These wells have a combined rated capacity of 250 gpm, but the wells cannot be run simultaneously due to their close proximity to each other and pumping depression (radius of influence) interference. In 2008, the Arcadia wells produced approximately 381 AF, and in 2009 ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 10 production was approximately 366 AF (see Table 1 and Figure 5). The most recent RSA (2017a) estimate of sustainable yield for this subbasin is between 750 and 880 AFY. Santa Monica well No. 1, historically counted as part of the Olympic Wellfield, is actually located two miles west of the Arcadia Wellfield and draws from the Arcadia subbasin (Figure 2). This well forms its own discrete pumping center. Other wells (i.e., Santa Monica well No. 5) that historically extracted from this pumping center are not currently active. The Olympic Wellfield has two currently active groundwater wells (Key Well Santa Monica No. 3, and Santa Monica well No. 4). In 2008, the Olympic Wellfield produced approximately 1,997 AF; in 2009 it produced approximately 2,064 AF (Table 1). The extraction curves as a function of time for the four Key Wells are shown in green on the appropriate figures, and on Plate 1. Depth to water as a function of time for these same four Key Wells is shown in blue. The most recent estimate of sustainable yield for the Olympic subbasin is between 1,600 and 1,700 AFY (RSA, 2017a). Construction details for each of the four selected Key Wells, obtained from logs for these wells filed with the California Department of Water Resources (CDWR) are included in Appendix C, and on Figures 3 through 6. All City of Santa Monica production wells are considered to be screened in the Silverado Aquifer within the San Pedro Formation. However, Key Wells Santa Monica No. 1 and Arcadia No. 4 appear to be screened across aquifers within both the Lakewood Formation and the San Pedro Formation. As discussed above in Section 2.3, the semi-confined nature of the Silverado Aquifer results in hydraulic connection with the shallower aquifers, and dewatering of those shallow aquifers when pumping occurs in the Silverado Aquifer. Columnar sections (stratigraphic profiles) for each Key Well, derived from the logs included in Appendix C, are also illustrated on Figures 3 through 6. These generalized stratigraphic profiles distinguish the primarily coarse-grained strata from those fine-grained units most susceptible to compression when dewatered under low-water-level conditions. The columnar sections group the sediments reported in the logs into two primary divisions: coarse-grained and fine-grained. Because rainfall is considered to be the primary source of groundwater recharge, and thus, to pose an impact on the water levels in the SMGB, the Key Well graphs on Figures 3 through 6 and Plate 1 also depict precipitation curves in black. These data were provided by RSA (2017b), and are available from the NOAA Western Regional Climate Data Center (WRCDC) at the Desert Research Institute, University of Nevada – Reno. The rainfall data were measured in a continuous rain gage (WRCDC No. 042214) located in Culver City that is considered representative for the SMGB area. The curves of “Accumulated Departure of Rainfall” depicted on Key Well Graphs (Figures 3 through 6 and Table 1) show annual patterns in rainfall for the available period of record. The accumulated rainfall departure values on the figures are plotted relative to the long-term average annual rainfall of 11.95 inches for the period for which there are data available, which extends from 1934 to 2016. The accumulated departure curve illustrates the temporal trends in the rainfall (recharge) data, and provides a useful format of comparison to well-production trends. Likewise, this curve also provides a framework for comparison to potential ground surface subsidence or uplift during the period for which SAR data are available. The “zero line” on the accumulated departure curves represents the long-term average annual rainfall (11.95 inches). Points plotted above the zero line represent years of higher- ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 11 than-average precipitation, whereas points plotted below that line represent years of less-than- average precipitation. Annual rainfall values are plotted on the Key Well Graphs as percentages relative to the running annual average, in order to illustrate how accumulated rainfall trends can represent a meaningful measure of water budget, and thus useful comparison to groundwater extractions (Table 1) and resultant water levels. Even though there may have been protracted “dry” periods in the SMGB (1944 through 1950, 1978 through 1991, 2005 through 2009), precipitation in subsequent years was sufficient to keep the rainfall totals above the long-term average annual value, and the net water budget out of overdraft conditions. 4.2 DInSAR RESULTS The DInSAR analyses utilizing stacked interferograms show that changes in the water level within the system of aquifers underlying the SMGB writ large do not readily correlate with any appreciable basin-wide land surface subsidence. The vertical elevation changes, if any, related to the water level in the aquifers appear to be too small to be reliably detected with stacked interferometry as they are close to the lower detection limit for this method. The interferometry results also suggest that in the SMGB this method is unable to capture tectonic- related elevation changes that may be occurring along the boundaries of the aquifers (i.e., faults or other groundwater barriers), either as a result of water level changes or in response to tectonic movements. The DInSAR method was also unable to identify any appreciable vertical (seismic related) movement occurring across any of the known faults in the SMGB. However, we cannot entirely preclude the possibility of horizontal movements, either as discrete small events or creep on the boundary faults. There may be a geologic cause for this lack of definition, such as coverage of the faults by generally unconsolidated and more transmissive recent alluvium. The current lack of reliable data could be mitigated by the installation of fixed GPS monitoring stations and cube-corner radar reflectors to enhance satellite data returns. Interestingly, preliminary analysis of individual interferogram pairs from the more recent satellite data (2015 onward) indicate the method could be utilized to detect positive deformation (surface inflation) due to recharge. 4.3 CORRELATION BETWEEN INTERFEROGRAMS AND KEY WELL DATA Noise in the satellite data caused by atmospheric disturbances, as well as surface deformation caused by tectonic activity, required the application of statistical methods in order to assess for a potential correlation (if any) between the DInSAR data and the well hydrographs. For each well where hydrographs were available for the same time period as the stacked interferograms, point deformation data were extracted from the "synthetic" interferograms representing the modeled deformation. These data were then tested against the hydrographs for a best-fit using a statistics software application. As the synthetic interferograms capture the change in elevation over the time period between acquisitions of the satellite images, the hydrographs were converted to reflect this as well, using the change in water level, rather than the absolute water level, in the statistical tests (discussed below). Furthermore, as the sampling intervals in both datasets are irregular and unevenly spaced, both datasets were resampled and trimmed (see appendix A). The first statistical test applied evaluated whether the sample populations of both the surface elevation and water level changes ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 12 follow normal (Gaussian) distributions. This test needed to be conducted prior to any correlation tests because standard normal distributions of parametric data improve the significance of subsequent test results. If both sets of data follow a Gaussian distribution, the attempted correlation would then be between the change in surface elevation (Δhsurface) and the change in water level ( Δhwater), with the assumption of a linear best-fit model using some specified confidence interval, ideally 95 percent or greater. The result of the statistical test would yield an equation for the best- fit line or curve, and an R2 value (Pearson correlation) describing how well the model correlates the ground surface response to the measured water level changes. The R2 value is always between 0 and 100 percent, with a higher value representing a better correlation between the model and the data (i.e., positive linear correlation between random sample populations of the two variables). When all point deformation (non-stacked) data were plotted in a single graph, it became apparent that there was noise present, as the graphs were all nearly identical in shape. Given that the wells are located in different subbasins, if the main source of ground surface deformation is groundwater extraction alone, the surface deformation should not be similar from one subbasin to the next, as groundwater extraction varies between subbasins. Similarly, deformation associated with local tectonic events should vary across the subbasins. Thus, we concluded that the source of the noise is likely either humidity in the atmosphere, or remaining phase-ramps that the SAR processor is unable to remove. As all points lie within a relatively small geographic area, we made the assumption that the disturbances are of the same magnitude and sign for all points in the region in each respective interferogram. To remove the noise we calculated the median for all data points belonging to a given interferogram, and subtracted this median value from the deformation values for each of the well locations. Finally, the deformation data for the key well locations were plotted together with the hydrological data on Figures 3 through 6 to visually make an initial non-quantitative correlation test (the surface deformations are shown in red on these figures and on Plate 1). The visual observations indicate that there appears to be a weak correlation between the localized surface deformation (subsidence) and groundwater water levels in the SMGB pumping centers for the time period between 1992 and 2016. Quantitative statistical correlation tests have not been able to show a correlation between the surface deformation and the hydrographs at a reasonable significance level because the bivariate Pearson coefficients (R2) for these correlations in all key wells resulted in values well below 50 percent. This can, at least in part, be explained by the gaps where data are missing in the hydrographs time-series, as well as the gaps in the interferometric data (e.g., dates for which images were not available, or are of too low coherence to be processed). Another explanation is that historical excess pumping that occurred beginning as early as the 1930s and 1940s, coupled with period intervals of drought, may have dewatered the compressible (fine- grained) strata for periods long enough to result in some degree of irrecoverable (inelastic) compaction (see Figures 7 and 8). ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 13 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 CONCLUSIONS Based on the data and methodology presented above, we conclude the following:  Only a weak, low-magnitude water-level-related surface deformation (subsidence) can be interpreted for the SMGB area from the stacked interferograms for the period between 1992 and 2016.  No long-term or regionally extensive compaction of sediments due to low groundwater levels has been observed outside the limited area of subsidence associated with the existing pumping centers.  The localized low magnitude of water-level-related surface deformation adjacent to the City’s wellfields is most likely the result of irreversible compaction due to dewatering of compressible strata that began as early as the 1930s and 1940s, when water levels in the aquifers were reportedly very low.  Because of the observed weak correlation between ground deformation and water levels as discussed above, some degree of future residual sediment dewatering and compaction cannot be ruled out near the Key Well pumping centers during periods of high rates of pumping.  A sequential analysis of paired interferograms through time is recommended, with an emphasis on more recent data obtained during the annual wet and dry seasons (October- April and May-September, respectively) that may provide useful information pertaining to short-term cyclical positive deformation (topographic inflation) due to inflow of natural recharge into the basin from distal sources and the subsequent short term topographic deflation due to dissipation of recharge in the subsurface via natural groundwater outflow. These data, if confirmed, would be useful in refining calculations of basin recharge volumes for sustainable yields and for planning adaptive pumping schedules. 5.2 RECOMMENDATIONS As a result of this study, ECI recommends the installation of between four and eight automated GPS monitoring stations within the City. The GPS stations would measure and record any future vertical displacements related to sediment compaction or tectonic activity and, possibly, more importantly, temporary topographic inflation caused by seasonal aquifer recharge. We recommend that these stations be installed in locations both proximal and distal to the Key Wells. The GPS station locations should be selected so that the system captures both the rapid response to pumping activities, and the slower response that occurs farther away as the groundwater levels rise and fall in cyclical response to natural recharge or the City’s planned reinjection for indirect potable reuse. To assist with adaptive management of the City’s groundwater, the automated GPS data should be correlated with future precipitation totals and static groundwater-level monitoring data collected by the City of Santa Monica pursuant to prevailing SGMA and California Statewide Groundwater Elevation Monitoring (CASGEM) requirements. The benefit of an automated GPS system to augment ground elevation data is that it will enable a more rigorous statistical correlation to water level time-series due to future reinjection ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 14 or pumping of the City’s closely clustered wells. The GPS system could help in identifying new potential well locations. Lastly, the GPS base stations would constitute a valuable planning resource for future City of Santa Monica Public Works Department Differential GPS (DGPS) and Real Time Kinematic (RTK) surveys. It is also recommended that the City of Santa Monica continue with annual InSAR surveys to be used in combination with the collected GPS data to help refine water resource planning and modeling efforts. To provide a more robust signal for the interferometry, we also suggest the installation of three to four permanent cube-corner radar reflectors in the area, as these will further increase the sensitivity of the interferometric surveys. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 15 6.0 REFERENCES AND SOURCES Amelung, F., Galloway, D.L., Bell, J.W., Zebker, H.A., and Laczniak, R.J, 1999, Sensing the ups and downs of Las Vegas: InSAR reveals structural control of land subsidence and aquifer- system deformation: Geology, Vol. 27, pp. 483–486. Argus, D.F., Heflin, M.B., Donnellan, A., Webb, F.H., Dong, D., Hurst, K.J., Jefferson, D.C., Lyzenga, G.A., Watkins, M.M., and Zumberge, J.F., 1999, Shortening and thickening of metropolitan Los Angeles measured and inferred by using geodesy: Geology, Vol. 27, pp. 703-706. Bawden, G.W., 2003, Separating groundwater and hydrocarbon-induced surface deformation from geodetic tectonic contraction measurements across metropolitan Los Angeles, California; In Prince, K.R. and Galloway, D.L., (editors), Proceedings of the Subsidence Interest Group Conference Technical Meeting held in Galveston, Texas, November 27-29, 2001: U.S. Geological Survey Open-File Report 03-308; available from http://pubs.usgs.gov/of/2003/ofr03-308/. Borchers, J.W., Carpenter, M., Kretsinger-Grabert, V., Dalgish, B., and Cannon, D., 2014, Land Subsidence from Groundwater Use in California: Water Education Foundation and Luhdorff & Scalmanini Consulting Engineers, 161p. California Department of Water Resources (CDWR), 1961, Planned Utilization of the Ground Water Basins of the Coastal Plain of Los Angeles County: Bulletin No. 104. California Department of Water Resources (CDWR), 2015, Sustainable Groundwater Management Program Draft Strategic Plan, 31p. California Geological Survey, 2017, Preliminary Review Map, Earthquake Fault Zones of Required Investigation, Beverly Hills 7.5 Minute Quadrangle, released July 13, 2017, to be superseded on or about January 11, 2018. Castle, R.O. and Yerkes, R.F., 1976, Recent Surface Movements in the Baldwin Hills, Los Angeles County, California: U.S. Geological Survey Professional Paper 882. Galloway, D.L. and Burbey, T.J., 2011, Review: Regional land subsidence accompanying groundwater extraction: Hydrogeology Journal, Vol. 19, No. 8, pp. 1459-1486. GeoTrans, Inc., 2005, Charnock Basin Groundwater Modeling – Groundwater Modeling Subtask 21.2: Technical Memorandum submitted to the Charnock Engineering Committee (CEC), July 22, 2005. Hu, J., Ding, X.L., Lia, Z.W., Zhang, L., Zhu, J.J., Sun, Q., and Gao, G.J., 2016, Vertical and horizontal displacements of Los Angeles from InSAR and GPS time series analysis: Resolving tectonic and anthropogenic motions: Journal of Geodynamics, Vol. 99, Sept 2016, pp. 27-38. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 16 ICF International Inc., 2015, Olympic Wellfield Site Conceptual Model, City of Santa Monica; consulting report, 34p. plus plates. ICF International Inc., 2017, Personal communication via email with G. Clarendin regarding Olympic Wellfield Water Level Elevations, Q3_2011 to present (Excel© spreadsheet) and Water Level Elevations Chart, Olympic Wellfield. Johnson, A.M., Fleming, R.W, Cruikshank, K.M. and Packard, R.F., 1996, Coactive faulting of the Northridge earthquake: U.S. Geological Survey Open-File Report 96-523. Kennedy/Jenks Consultants (KJC), 2011, Feasibility Report for Development of Groundwater Resources in the Santa Monica and Hollywood Basins; consulting report prepared for Los Angeles City Department and Power, December 2011, 158p. Kennedy/Jenks Consultants (KJC), 2015, City of Santa Monica Sustainable Water Supply Master Plan; consulting report prepared for the City of Santa Monica, 225p. Lanari R., Lundgren P., Mariarosaria M., and Casu, F., 2004, Satellite radar interferometry time- series analysis of surface deformation for Los Angeles, California: Geophysical Research Letters, Vol. 31, No. 23, 16 Dec., 2004, 5p. Olson, B.P.E., 2017, The Hollywood, Santa Monica and Newport-Inglewood Faults in the Beverly Hills and Topanga 7.5’ Quadrangles: California Geological Survey Fault Evaluation Report No. FER-259, dated June 28, 2017, released July 13, 2017, 72p. Orange County Water District, 2015, Groundwater Management Plan 2015 Update, 10p. Poland, J.F., (editor) and others, 1984, Guidebook to Studies of Land Subsidence due to Ground- Water Withdrawal: Studies and Reports in Hydrology, prepared for the International Hydrological Programme, Working Group 8.4: United Nations Educational, Scientific and Cultural Organization, Paris, France, 305p. plus appendices; available from http://unesdoc.unesco.org/images/0006/000651/065167eo.pdf Poland, J.F., Garrett, A.A., and Sinnott, A., 1959, Geology, Hydrology, and Chemical Character of Ground Waters in the Torrance-Santa Monica Area, California: U.S. Geological Survey Water-Supply Paper 1461. Reichard, E.G., Land, M., Crawford, S.M., Johnson, T., Everett, R.R., Kulshan, T.V., Ponti, D.J., Halford, K.J., Johnson, T.A., Paybins, K.S., and Nishikawa, T., 2003, Geohydrology, geochemistry, and ground-water simulation – Optimization of the Central and West Coast Basins, Los Angeles County, California: U.S. Geological Survey Water Resource Investigation Report 03-4065. Richard C. Slade & Associates (RSA), 2013, Conceptual Groundwater Basin Model and Assessment of Available Groundwater Supplies, Santa Monica Groundwater Basin: consulting report prepared for the City of Santa Monica, 119p. plus appendices. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Report - Page 17 Richard C. Slade & Associates (RSA), 2017, Draft Preliminary Study of the Sustainable Yield of the Santa Monica Groundwater Basin; consulting report prepared for the City of Santa Monica Water Resources Division. Richard C. Slade & Associates (RSA), 2017, Personal communication via e-mail with E. LaPensee who provided to us hydrographs of Santa Monica Wells in an Excel spreadsheet, on 25 Jan. 2017. Sneed, M., 2016, Land Subsidence: The Lowdown on the Drawdown: U.S. Geological Survey and California Groundwater Resources Association Webinar, March 23, 2016. Water Education Foundation, 2015, The 2014 Sustainable Groundwater Management Act: A Handbook to Understanding and Implementing the Law; available from http://www.watereducation.org/publication/2014-sustainable-groundwater-management- act Yerkes, R.F., McCulloh, T.H., Schoellhamer, J.E., and Vedder, J.G., 1965, Geology of the Los Angeles basin, California—An Introduction: U.S. Geological Survey Professional Paper 420-A, 57p. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Figures and Plate FIGURES and PLATE Water depth below top-of-well casing (in Feet) Rainfall (percent cumulative departure from annual average for the period between 1975 and 2016) Annual subbasin groundwater production (in Acre-Feet) Explanation Chiefly fine-grained compressible sediments (CL,CH,ML,MH,SC,GC) Chiefly coarse-grained sediments with low compressibility (SW,SP,SM,SG,GP,GW) Surface deformation (in Millimeters) Well Construction Schematic (Depth=ft bgs) B l a n k C a s i n g P u m p C o l u m n P e r f o r a t e d I n t e r v a l 2 2 0 -3 9 0 f t b g s P u m p a t ??? T.D.=410 ft bgs G e n e r a l S t r a t i g r a p h i c P r o f i l e (F e e t B e l o w G r o u n d S u r f a c e ) S t a t i c W a t e r D e p t h B e l o w G r o u n d S u r f a c e (F e e t ) Date R a i n f a l l G r o u n d w a t e r P r o d u c t i o n (A c r e -F e e t ) S u r f a c e D e f o r m a t i o n (M i l l i m e t e r s ) -400 -300 -200 -100 0 100 200 300 400 500 6000 20 40 60 80 100 120 140 160 180 200 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 0 5 10 15 20 25 30 Key Well:Charnock Subbasin Charnock Well No.16 0 ft Project Number:3615 Date:September 2017 Figure 3WellSchematicsandStratigraphicProfile,Historical Water Depth,Rainfall,Groundwater Production and Surface Deformation for Charnock Well No.16 -300 -200 0 100 200 300 400 500 6000 20 40 60 80 100 120 140 160 180 200 1990 1995 2000 2005 2010 2015 2020 0 500 1000 1500 2000 2500 3000 3500 -400 -100 Key Well:Olympic Subbasin Santa Monica Well No.3 S t a t i c W a t e r D e p t h B e l o w G r o u n d S u r f a c e (F e e t ) -7 -6 -5 -4 -3 -2 -1 0 -8 Figure 4 Water depth below top-of-well casing (in Feet) Rainfall (percent cumulative departure from annual average for the period between 1975 and 2016) Annual subbasin groundwater production (in Acre-Feet) Explanation Chiefly fine-grained compressible sediments (CL,CH,ML,MH,SC,GC) Chiefly coarse-grained sediments with low compressibility (SW,SP,SM,SG,GP,GW) Surface deformation (in Millimeters) Well Construction Schematic (Depth=ft bgs) G e n e r a l S t r a t i g r a p h i c P r o f i l e (F e e t B e l o w G r o u n d S u r f a c e ) Perforated Intervals 210-270 300-380 410-430 490-530 ftbgs P u m p C o l u m n B l a n k C a s i n g 0 ft R a i n f a l l G r o u n d w a t e r P r o d u c t i o n (A c r e -F e e t ) S u r f a c e D e f o r m a t i o n (M i l l i m e t e r s ) Project Number:3615 Date:September 2017 Well Schematics and Stratigraphic Profile,Historical Water Depth,Rainfall,Groundwater Production,and Surface Deformation for Santa Monica Well No.3 Date 1975 1980 1985 T.D.=550 ft bgs Project Number:3615 Date:September 2017 Well Schematics and Stratigraphic Profile,Historical Water Depth,Rainfall,Groundwater Production,and Surface Deformation for Arcadia Well No.4 Date G e n e r a l S t r a t i g r a p h i c P r o f i l e (F e e t B e l o w G r o u n d S u r f a c e ) R a i n f a l l Date G r o u n d w a t e r P r o d u c t i o n (A c r e -F e e t ) S u r f a c e D e f o r m a t i o n (M i l l i m e t e r s ) Well Construction Schematic (Depth-ft bgs) B l a n k C a s i n g P u m p C o l u m n P e r f o r a t e d i n t e r v a l s : 8 5 -2 1 8 f t b g s P u m p a t ??? T.D.=235 ft bgs Figure 5 Key Well:Arcadia Subbasin Arcadia Well No.4 -400 -300 -200 -100 0 100 200 300 400 500 6000 20 40 60 80 100 120 140 160 180 200 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 0 100 200 300 400 500 600 700 800 900 10000ft S t a t i c W a t e r D e p t h B e l o w G r o u n d S u r f a c e (F e e t ) -40 -35 -30 -25 -20 -15 -10 -5 0 Water depth below top-of-well casing (in Feet) Rainfall (percent cumulative departure from annual average for the period between 1975 and 2016) Annual subbasin groundwater production (in Acre-Feet) Explanation Chiefly fine-grained compressible sediments (CL,CH,ML,MH,SC,GC) Chiefly coarse-grained sediments with low compressibility (SW,SP,SM,SG,GP,GW) Surface deformation (in Millimeters) Water depth below top-of-well casing (in Feet) Rainfall (percent cumulative departure from annual average for the period between 1975 and 2016) Annual subbasin groundwater production (in Acre-Feet) Explanation Chiefly fine-grained compressible sediments (CL,CH,ML,MH,SC,GC) Chiefly coarse-grained sediments with low compressibility (SW,SP,SM,SG,GP,GW) Surface deformation (in Millimeters) Project Number:3615 Date:September 2017 Figure 6 -400 -300 -200 -100 0 100 200 300 400 5000 20 40 60 80 100 120 160 180 200 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 S t a t i c W a t e r D e p t h B e l o w G r o u n d S u r f a c e 140 B o t t o m o f s c r e e n 2 5 0 ' T.D.=275bgs 0 ft P e r f o r a t e d I n t e r v a l 1 5 1 '-2 5 0 ' P u m p C o l u m n Pump at ??? 1 4 " B l a n k C a s i n g 50 100 150 200 250 300 350 400 0 Key Well:North Arcadia Subbasin Santa Monica Well No.1 G r o u n d w a t e r P r o d u c t i o n (A c r e -F e e t ) R a i n f a l l -25 -20 -15 15 -10 -5 0 S u r f a c e D e f o r m a t i o n (M i l l i m e t e r s ) Well Schematics and Stratigraphic Profile,Historical Water Depth,Rainfall,Groundwater Production,and Surface Deformation for Santa Monica Well No.1 Well Construction Schematic (Depth=ft bgs) G e n e r a l S t r a t i g r a p h i c P r o f i l e (F e e t B e l o w G r o u n d S u r f a c e ) Date ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Table TABLE ECI Project No. 3615 September 15, 2017 YEAR Arcadia Charnock Olympic ("Santa Monica")TOTAL 1975 872 5,475 1,382 7,729 1976 812 5,039 1,580 7,431 1977 646 5,356 1,260 7,262 1978 476 3,237 503 4,216 1979 545 3,555 1,446 5,546 1980 516 4,355 1,019 5,890 1981 411 5,340 233 5,984 1982 74 4,901 2,177 7,152 1983 - 5,506 3,173 8,679 1984 75 6,168 3,119 9,362 1985 376 5,644 2,884 8,904 1986 377 6,598 2,574 9,549 1987 371 7,513 834 8,718 1988 372 8,111 387 8,870 1989 357 6,363 457 7,177 1990 389 4,132 469 4,990 1991 417 4,728 387 5,532 1992 396 6,486 981 7,863 1993 390 6,153 2,867 9,410 1994 419 5,906 3,126 9,451 1995 542 6,322 3,176 10,040 1996 370 2,284 3,044 5,698 1997 - - 2,820 2,820 1998 - - 2,642 2,642 1999 - - 2,937 2,937 2000 - - 2,912 2,912 2001 387 - 2,809 3,196 2002 467 - 1,824 2,291 2003 455 - 593 1,048 2004 137 - 385 522 2005 395 - 1,495 1,890 2006 387 - 1,365 1,752 2007 374 - 1,619 1,993 2008 360 - 1,663 2,023 2009 340 - 1,722 2,062 2010 290 593 2,436 3,319 2011 269 4,222 1,967 6,458 2012 258 5,458 2,734 8,450 2013 273 6,141 2,454 8,868 2014 355 8,284 1,541 10,180 2015 378 8,015 2,287 10,680 2016 339 8,372 2,246 10,957 Sources: City of Santa Monica Water Resources Protection Program; Richard C. Slade & Associates February, 2013 report and personal communication, 2017 . Table 1: Santa Monica Groundwater Basin Production History, 1975-2016 Annual Production (in Acre-Feet) By Wellfield / Subbasin DInSAR Study of the Santa Monica Groundwater Basin Area Table 1 ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Appendix A APPENDIX A: ADDITIONAL TECHNICAL INFORMATION REGARDING THE DInSAR METHOD AND STATISTICAL ANALYSES COMPLETED AS PART OF THIS STUDY ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-1 APPENDIX A: ADDITIONAL TECHNICAL INFORMATION REGARDING THE DInSAR METHOD AND THE STATISTICAL ANALYSES COMPLETED AS PART OF THIS STUDY More In-Depth Description of the DInSAR Method as Used in This Study DInSAR as utilized in this study is a satellite, airborne, radar-based system that generates high- resolution remote sensing imagery. The onboard signal processing system uses the magnitude and phase of the received signals over successive pulses from elements of a 'synthetic aperture' to create an image consisting of pixels containing both the phase and amplitude information. The distance the SAR device travels over a target in the time taken for the radar pulses to return to the antenna creates the large "synthetic" antenna aperture (the "size" of the antenna). Typically, the larger the aperture, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or 'synthetic' (a moving antenna). This allows SAR to create high- resolution images with the comparatively small antennas that fit onboard a satellite or aircraft. The phase information of each image pixel represents the complex vector sum of the radar echoes from all scattering elements within a corresponding resolution cell on the ground, covering an area of approximately 20 x 5 meters for the ERS-1, -2 and Envisat satellites. Other satellites may have different resolution cell sizes, but the final pixel size is usually resampled to a square shape of 20 to 50 meters regardless of the size of the original cells. The return phase of the signal from each scattering center has its phase determined by the two-way range to the satellite and this will typically vary by several hundred wavelengths (ERS-1, -2, Envisat 56.66 mm) across a typical resolution cell. The phase of an image pixel by itself is thus a random and not very meaningful parameter. There is, however, a correlation between the phase information in corresponding pixels in scenes covering the same area, and any movements that have occurred between the acquisitions of the scenes will be represented by a phase shift. For this assumption to be valid the satellite needs to be located very precisely over the target area and any difference in the repeat orbits will introduce phase shifts that need to be removed mathematically. Depending on the intended use of the interferograms, detecting ground movements or generating Digital Elevation Models (DEMs), the maximum allowable offsets in the orbits differ. For DEM generation, a maximum value of the perpendicular offset (offset between orbits) is around 1100 m, whereas values of less than 250 m are needed to measure surface deformation. A high degree of control over the orbits of the satellites is also imperative if the SAR images are to be used for interferometric purposes. In addition to problems with phase shift introduced by offsets in the orbits, other problems will also occur. Examples are loss of coherence caused by differences in the viewing geometry, and ambiguities caused by the relief giving false signals in the interferogram. There are also other factors that may reduce or even totally compromise the quality of the DInSAR results. The most important one is related to temporal decorrelation phenomena caused by the variation of the electromagnetic properties of the radar targets. If the phase reflectivity value of a certain image pixel changes with time, the generation of an interferogram, i.e. the computation of the difference between the phase values of two SAR images; cannot highlight the displacement values. The impact of temporal decorrelation phenomena increases as the temporal baseline of the interferogram (i.e. the time lag between the two SAR acquisitions) increases. Apart from phase decorrelation, propagation effects in both the troposphere and the ionosphere can differ significantly during the first and the second ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-2 acquisition, thus creating phase disturbances that at best will hinder the interpretation of SAR interferograms, or at worst, completely prevent the processing of the satellite data. Given all these potential issues, only a small number of the available archived scenes are suitable for the generation of interferograms. In general, it can also be said that the availability varies between the ages of the different satellite systems, with more modern systems having greater reliability. This is mostly the result of better control of the orbits of the satellites, but also because of developments that have given the onboard signal processing systems and computers better capabilities. The interference pattern is a function of the geometries of the orbits as well as the topography of the target area. By analyzing the interference patterns, and knowing the precise orbits, the topography can be calculated and, if the topography also is known, any changes in the topography can be calculated from the interferogram by removing the topographic effects utilizing an existing DEM. The difference in phase between the SAR images is usually represented by color bands in such a way that a movement corresponding to half the wavelength of the radar is shown as a complete color cycle in a color band. Apart from phase information, the quality of the correlation, (the ‘coherence') between two SAR images can also be determined. Such coherence values are related to the nature of the ground surface. Any chaotic movements of the scatterers in the target area between the acquisitions will cause the coherence to be low. Open water and active agricultural areas are usually totally decorrelated, whereas urban areas and areas free of vegetation are more likely to have a high coherence over extended periods of time. Low coherence makes it impossible to calculate the phase shift, and thus a high degree of coherence is imperative in the areas of interest. Processing the raw SAR data to create interferograms is a multi-step operation involving Fourier transforms to extract the radar echoes, and other complex mathematics. The technical details of these procedures are beyond the scope of this report, but are described in detail in Lanari et al. (2004), and Hu et al., (2016). Although several InSAR processing packages are available, we chose GMTSAR, which was developed by the Scripps Institution of Oceanography and the University of Hawaii. There are two reasons for choosing GMTSAR over other available software packages. First, the software is in the public domain and free to use by anyone without restrictions, as it is currently released as open source under the GNU General Public License. Second, when the European Space Agency opened their archives of ERS satellite data for general use in early April 2017, we found that they had changed the data format and virtually no other commercially available software was capable to read the new format. The open nature of GMTSAR allowed us to write a new pre-processor for the new file format, allowing us to process the data successfully. The software can be divided into three parts: a. A pre-processor responsible for importing and converting satellite data (ERS-1/2, ENVISAT, ALOS-1, TerraSAR-X, COSMOS-SkyMed, Radarsat-2, Sentinel-1A/B, and ALOS-2) to the internal native format used by GMTSAR. b. The InSAR processor, which focuses and aligns stacks of images, maps topography into phase, and forms the complex interferograms. c. The post-processor, which filters the interferograms and constructs interferometric products of phase, coherence, phase gradient, and line-of sight displacement in both radar and geographic coordinates. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-3 As described above, the interferograms produced by subtracting phase data from separate radar images result in an image where every pixel describes the displacement that has occurred between the acquisitions of the images. However, the detected displacement will also contain an error of unknown magnitude due to atmospheric interference, which means that any deformation along line-of-sight only can be taken as an approximation for a single interferogram. The SBAS algorithm uses a number of interferograms (>3) and applies a least squares curve fitting on every corresponding pixel in the included interferograms to create an image where the pixels represent the velocity in millimeters per year that best fits any displacement that occurs over time. In addition, the software also outputs "synthetic" interferograms with the cumulative displacement that has occurred between the acquisitions of the radar images. It is also creating maps showing the residuals between the expected and measured displacements. A small residual means that there is a good fit between the model for the displacement and the interferometrically detected displacement of the same pixel. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-4 Specific Statistical Analyses Used to Compare the Changes in Ground Elevation (Delta h) with Depth to Water (DTW) Minitab Regression Analysis: Delta_h versus DTW, Santa Monica Well No. 1 Analysis of Variance: Source DF Adj SS Adj MS F-Value P-Value Regression 1 62287 62287.4 2491.02 0.000 DTW 1 62287 62287.4 2491.02 0.000 Error 7533 188361 25.0 Lack-of-Fit 7206 187396 26.0 8.82 0.000 Pure Error 327 965 2.9 Total 7534 250648 Model Summary: S R-sq R-sq(adj) R-sq(pred) 5.00048 24.85% 24.84% 24.82% Coefficients: Term Coef SE Coef T-Value P-Value VIF Constant 1.993 0.312 6.39 0.000 DTW -0.10580 0.00212 -49.91 0.000 1.00 Regression Equation: Delta_h(mm) = 1.993 - 0.10580 DTW(ft) ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-5 Minitab Regression Analysis: Delta_h versus DTW, Santa Monica Well No. 3 Analysis of Variance: Source DF Adj SS Adj MS F-Value P-Value Regression 1 2648.6 2648.61 844.28 0.000 DTW 1 2648.6 2648.61 844.28 0.000 Error 8355 26210.8 3.14 Lack-of-Fit 7685 25959.1 3.38 8.99 0.000 Pure Error 670 251.7 0.38 Total 8356 28859.4 Model Summary: S R-sq R-sq(adj) R-sq(pred) 1.77120 9.18% 9.17% 9.14% Coefficients: Term Coef SE Coef T-Value P-Value VIF Constant 0.535 0.122 4.37 0.000 DTW -0.027913 0.000961 -29.06 0.000 1.00 Regression Equation: Delta_h(mm) = 0.535 - 0.027913 DTW(ft) ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-6 Minitab Regression Analysis: Delta_h versus DTW, Charnock Well No. 15 Analysis of Variance: Source DF Adj SS Adj MS F-Value P-Value Regression 1 423524 423524 17718.47 0.000 DTW 1 423524 423524 17718.47 0.000 Error 7000 167321 24 Lack-of-Fit 6659 166009 25 6.48 0.000 Pure Error 341 1311 4 Total 7001 590845 Model Summary: S R-sq R-sq(adj) R-sq(pred) 4.88907 71.68% 71.68% 71.67% Coefficients: Term Coef SE Coef T-Value P-Value VIF Constant 45.271 0.203 223.54 0.000 DTW -0.25082 0.00188 -133.11 0.000 1.00 Regression Equation: Delta_h(mm) = 45.271 - 0.25082 DTW(ft) ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-7 Minitab Regression Analysis: Delta_h versus DTW, Charnock Well No. 16 Analysis of Variance: Source DF Adj SS Adj MS F-Value P-Value Regression 1 201243 201243 5928.61 0.000 DTW 1 201243 201243 5928.61 0.000 Error 8660 293958 34 Lack-of-Fit 8045 293150 36 27.74 0.000 Pure Error 615 808 1 Total 8661 495201 Model Summary: S R-sq R-sq(adj) R-sq(pred) 5.82618 40.64% 40.63% 40.61% Coefficients: Term Coef SE Coef T-Value P-Value VIF Constant 35.776 0.244 146.43 0.000 DTW -0.16149 0.00210 -77.00 0.000 1.00 Regression Equation: Delta_h(mm) = 35.776 - 0.16149 DTW(ft) ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-8 Minitab Regression Analysis: Delta_h versus DTW, Arcadia Well No. 4 Analysis of Variance: Source DF Adj SS Adj MS F-Value P-Value Regression 1 28888 28888.1 237.15 0.000 DTW 1 28888 28888.1 237.15 0.000 Error 8752 1066092 121.8 Lack-of-Fit 7054 1037442 147.1 8.72 0.000 Pure Error 1698 28649 16.9 Total 8753 1094980 Model Summary: S R-sq R-sq(adj) R-sq(pred) 11.0368 2.64% 2.63% 2.58% Coefficients: Term Coef SE Coef T-Value P-Value VIF Constant -25.177 0.296 -85.16 0.000 DTW 0.14624 0.00950 15.40 0.000 1.00 Regression Equation: Delta_h(mm) = -25.177 + 0.14624 DTW(ft) ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Page A-9 References Hu, J., Ding, X.L., Lia, Z.W., Zhang, L., Zhu, J.J., Sun, Q., and Gao, G.J., 2016, Vertical and horizontal displacements of Los Angeles from InSAR and GPS time series analysis: Resolving tectonic and anthropogenic motions: Journal of Geodynamics, Vol. 99, Sept 2016, pp. 27-38. Lanari R., Lundgren P., Mariarosaria M., and Casu, F., 2004, Satellite radar interferometry time- series analysis of surface deformation for Los Angeles, California: Geophysical Research Letters, Vol. 31, No. 23, 16 Dec., 2004, 5p. ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Appendix B APPENDIX B: INTERFEROGRAMS ANALYZED ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Appendix B- Page B-1 List of satellite scenes used in the study: ERS, Stack 1 Date Time Track Orbit Satellite 19920914 18:34:29 442 06098 ERS-1 19960214 18:34:28 442 23977 ERS-1 19991111 18:34:17 442 23843 ERS-2 19991216 18:34:17 442 24344 ERS-2 20000921 18:34:32 442 28352 ERS-2 ERS, Stack 2 Date Time Track Orbit Satellite 19950823 18:34:28 442 21472 ERS-1 19960912 18:34:26 442 07310 ERS-2 19970619 18:34:25 442 11318 ERS-2 19981126 18:34:14 442 18833 ERS-2 19990311 18:34:17 442 20336 ERS-2 20001026 18:34:27 442 28853 ERS-2 20001130 18:34:20 442 29354 ERS-2 ENVISAT Stack 1 Date Time Track Orbit Satellite 20021028 05:43:01 392 03452 ENVISAT 20030106 05:42:56 392 04454 ENVISAT 20040614 05:43:07 392 11969 ENVISAT 20041101 05:43:08 392 13973 ENVISAT 20050321 05:43:01 392 15977 ENVISAT 20060515 05:43:00 392 21989 ENVISAT 20060619 05:43:03 392 22490 ENVISAT 20070219 05:42:58 392 25997 ENVISAT Also downloaded and processed but not used in any stacks due to low coherency. Date Time Track Orbit Satellite 20021202 05:42:59 392 03953 ENVISAT 20041206 05:43:04 392 14474 ENVISAT 20051121 05:43:05 392 19484 ENVISAT 20061211 05:43:04 392 24995 ENVISAT 20070709 05:43:02 392 28001 ENVISAT Standalone ALOS interferogram Date Time Path Orbit Granule ID 2008-01-20 06:22:21 217 10593 PASL10C0801200622261208200010 2010-07-28 06:23:39 217 24013 PASL10C1007280623441208200011 ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Appendix B- Page B-2 Sentinel-1, Stack 1 Date Time Absolute orbit Swath 2015-01-26 13:51:57 4343 3 2015-07-25 13:52:00 6968 3 2015-08-18 13:52:01 7318 3 2015-10-29 13:51:59 8368 3 2015-11-22 13:51:57 8718 3 2015-12-16 13:51:56 9068 3 2016-03-21 13:51:55 10468 3 2016-05-08 13:51:57 11168 3 2016-06-01 13:52:01 11518 3 2016-08-24 13:52:15 12743 3 2016-11-16 13:52:01 13968 3 2016-11-28 13:52:15 14143 3 ECI Project No. 3615 September 15, 2017 DInSAR Study of the Santa Monica Groundwater Basin Area Appendix C APPENDIX C: LOGS OF KEY WELLS, SANTA MONICA GROUNDWATER BASIN January 8, 2018  Re:  Agenda Item 9, January 9, 2018 City Council Meeting (Calendar Year 2018 Water Rate Adjustment)  Dear Santa Monica City Council members,  As members of the Santa Monica Task Force on the Environment (TFE), we write to (1) support the Staff  recommendation to 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, (2) object to additional  diversions of settlement funds from the groundwater settlements to City projects unrelated to water  use, including the City Yard project and the new City Services building.  By way of context, we have received numerous presentations on the City’s water rate study, water rate  increase recommendations, water conservation ordinance, drought response and enforcement, water  neutrality ordinance, progress towards achieving water self‐sufficiency by 2020, the SWIP, approaches  to determining the sustainable yield of our local aquifers, and the utilization of settlement funds from  Santa Monica’s extraordinarily successful efforts to get polluters to pay for the restoration of the city’s  precious groundwater supplies.  As you may recall, the TFE proposed the target of local self‐sufficiency by 2020 as well as the concept for  the water neutrality ordinance.  In addition, the TFE was highly critical of the last water rate study that  proposed rate increases of 9‐13% for five years.  We closely reviewed that study and recommended a  more modest rate increase to pay for critical water infrastructure capital improvement projects. Based  on the TFE analysis, we recommended a much smaller rate increase that focused on essential water  distribution and treatment projects that enhanced the City’s reliability and resiliency.  We bring up this extensive recent history to remind the City Council that the TFE has been there to  provide strong water supply and water quality expertise.  As such, as members of the TFE we feel that it  is urgent for the City to utilize the remaining groundwater settlement funds for the City’s urgent water  supply and water quality needs.   In the summer of 2017, the TFE asked for detailed information on the status of the groundwater  settlement funds.  In the fall, having seen a lack of viable sustainable water management plan, a  sustainable yield study, or current information on the status of the City’s groundwater remediation  efforts and strong technical estimates on the time and effort necessary to achieve site closures for the  City’s contaminated aquifers, the TFE recommended that the groundwater settlement funds be  earmarked towards the City’s water needs.  We provided this recommendation to the City Council twice  during the fall.  In November and December of 2017, the TFE was provided with information on how the groundwater  settlement funds have been utilized to date and how staff proposed to use the remaining funds in the  future. The staff memo to Council did not provide an up to date current status on remediation efforts,  annual cost of remediation, remaining funds allocated for remediation ($33.6M for the Charnock  wellfield as of 2012‐13, but no value as of 2017).  Also, no clear information on how much of the Gillette  allocated $15.2 M and $4.6M contingency for the Olympic wellfield is left or the length of time needed  to complete remediation of the City’s groundwater supplies.  Also, the memo didn’t provide any  Item 9-A 01/09/18 Item 9-A 01/09/18 information on additional treatment needs for contaminated groundwater in the Olympic wellfield  including a needed upgrade of the water treatment facility at Arcadia. During this time the TFE was very  surprised to learn that the City had already allocated approximately $56.4 million ($49.4M for the City  Yard project and $7M for the City Services Building) of the remaining unallocated $122 M as part of the  2017‐18 approved budget.  We were extremely dismayed to learn of this allocation months after the  fact rather than during the 2017‐18 budget process.  This was completely inconsistent with how the City  has worked with the TFE on environmental budget issues over the last 25 years.  With so much uncertainty in Santa Monica’s water future, utilization of an additional $64 M for the City  Yard facilities as proposed by staff would be premature and frankly, unethical. Although the settlement  agreements do not, by their express terms, constrain the city’s use of the settlement proceeds, it isn’t  morally just to utilize those settlement funds for new city offices and facilities when the settlement  funds were negotiated based on the cost to restore the City’s precious groundwater resources. In fact,  utilization of settlement funds in this manner runs contrary to the intent of the Sustainable Rights  Ordinance which emphasizes Santa Monica residents’ rights to a clean and sustainable groundwater  basin for generations to come.  Also, further utilization of the settlement funds for unrelated city  projects sets a horrible precedent for future City litigation efforts.  Why would a defendant agree to the  City’s proposed settlement terms to provide a remedy to historic harm if the City has a history of  inflating the magnitude of that harm to fill the City’s General Fund coffers?  Before you Tuesday night is a decision on water rates for Santa Monica.  This is a discussion that is  inextricably linked to the City’s substantial water management efforts.  After all, sustainable water  management treats all water as “one water” whether it is from groundwater, stormwater, recycled  water or conservation. We strongly urge the City Council to follow the staff recommendation and cap  any water rate increase at 5% for one year.  Also, please authorize a new rate study shortly after the  completion of the long overdue sustainable water management plan and sustainable yield study.  In  addition, please ask staff for an update on the proposed projects from the last rate study and CIP with a  new CIP list with cost and timeline for these projects.  And please utilize the remaining groundwater  settlement funds for aquifer remediation until the sites are closed by the Los Angeles Regional Water  Quality Control Board.  To ask for ratepayers to cover any of the costs of groundwater remediation or  additional water treatment is unethical given that a large pot of money exists to do exactly this.  Already  the city has borrowed $60 million from the State Revolving Fund for projects (the SWIP) to augment  local water supplies with stormwater and recycled water.  Ratepayers will have to pay back this loan on  their water bill.  The city needs to keep the remaining $66M of unallocated settlement funds to restore  and sustain one of Santa Monica’s most precious natural resources: our groundwater supply.  Sincerely,  M a r k   G o l d      D a v i d   P e t t i t   Item 9-A 01/09/18 Item 9-A 01/09/18 January 8, 2018  Re:  Agenda Item 9, January 9, 2018 City Council Meeting (Calendar Year 2018 Water Rate Adjustment)  Dear Santa Monica City Council members,  As members of the Santa Monica Task Force on the Environment (TFE), we write to (1) support the Staff  recommendation to 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, (2) object to additional  diversions of settlement funds from the groundwater settlements to City projects unrelated to water  use, including the City Yard project and the new City Services building.  By way of context, we have received numerous presentations on the City’s water rate study, water rate  increase recommendations, water conservation ordinance, drought response and enforcement, water  neutrality ordinance, progress towards achieving water self‐sufficiency by 2020, the SWIP, approaches  to determining the sustainable yield of our local aquifers, and the utilization of settlement funds from  Santa Monica’s extraordinarily successful efforts to get polluters to pay for the restoration of the city’s  precious groundwater supplies.  As you may recall, the TFE proposed the target of local self‐sufficiency by 2020 as well as the concept for  the water neutrality ordinance.  In addition, the TFE was highly critical of the last water rate study that  proposed rate increases of 9‐13% for five years.  We closely reviewed that study and recommended a  more modest rate increase to pay for critical water infrastructure capital improvement projects. Based  on the TFE analysis, we recommended a much smaller rate increase that focused on essential water  distribution and treatment projects that enhanced the City’s reliability and resiliency.  We bring up this extensive recent history to remind the City Council that the TFE has been there to  provide strong water supply and water quality expertise.  As such, as members of the TFE we feel that it  is urgent for the City to utilize the remaining groundwater settlement funds for the City’s urgent water  supply and water quality needs.   In the summer of 2017, the TFE asked for detailed information on the status of the groundwater  settlement funds.  In the fall, having seen a lack of viable sustainable water management plan, a  sustainable yield study, or current information on the status of the City’s groundwater remediation  efforts and strong technical estimates on the time and effort necessary to achieve site closures for the  City’s contaminated aquifers, the TFE recommended that the groundwater settlement funds be  earmarked towards the City’s water needs.  We provided this recommendation to the City Council twice  during the fall.  In November and December of 2017, the TFE was provided with information on how the groundwater  settlement funds have been utilized to date and how staff proposed to use the remaining funds in the  future. The staff memo to Council did not provide an up to date current status on remediation efforts,  annual cost of remediation, remaining funds allocated for remediation ($33.6M for the Charnock  wellfield as of 2012‐13, but no value as of 2017).  Also, no clear information on how much of the Gillette  allocated $15.2 M and $4.6M contingency for the Olympic wellfield is left or the length of time needed  to complete remediation of the City’s groundwater supplies.  Also, the memo didn’t provide any  Item 9-A 01/09/18 Item 9-A 01/09/18 information on additional treatment needs for contaminated groundwater in the Olympic wellfield  including a needed upgrade of the water treatment facility at Arcadia. During this time the TFE was very  surprised to learn that the City had already allocated approximately $56.4 million ($49.4M for the City  Yard project and $7M for the City Services Building) of the remaining unallocated $122 M as part of the  2017‐18 approved budget.  We were extremely dismayed to learn of this allocation months after the  fact rather than during the 2017‐18 budget process.  This was completely inconsistent with how the City  has worked with the TFE on environmental budget issues over the last 25 years.  With so much uncertainty in Santa Monica’s water future, utilization of an additional $64 M for the City  Yard facilities as proposed by staff would be premature and frankly, unethical. Although the settlement  agreements do not, by their express terms, constrain the city’s use of the settlement proceeds, it isn’t  morally just to utilize those settlement funds for new city offices and facilities when the settlement  funds were negotiated based on the cost to restore the City’s precious groundwater resources. In fact,  utilization of settlement funds in this manner runs contrary to the intent of the Sustainable Rights  Ordinance which emphasizes Santa Monica residents’ rights to a clean and sustainable groundwater  basin for generations to come.  Also, further utilization of the settlement funds for unrelated city  projects sets a horrible precedent for future City litigation efforts.  Why would a defendant agree to the  City’s proposed settlement terms to provide a remedy to historic harm if the City has a history of  inflating the magnitude of that harm to fill the City’s General Fund coffers?  Before you Tuesday night is a decision on water rates for Santa Monica.  This is a discussion that is  inextricably linked to the City’s substantial water management efforts.  After all, sustainable water  management treats all water as “one water” whether it is from groundwater, stormwater, recycled  water or conservation. We strongly urge the City Council to follow the staff recommendation and cap  any water rate increase at 5% for one year.  Also, please authorize a new rate study shortly after the  completion of the long overdue sustainable water management plan and sustainable yield study.  In  addition, please ask staff for an update on the proposed projects from the last rate study and CIP with a  new CIP list with cost and timeline for these projects.  And please utilize the remaining groundwater  settlement funds for aquifer remediation until the sites are closed by the Los Angeles Regional Water  Quality Control Board.  To ask for ratepayers to cover any of the costs of groundwater remediation or  additional water treatment is unethical given that a large pot of money exists to do exactly this.  Already  the city has borrowed $60 million from the State Revolving Fund for projects (the SWIP) to augment  local water supplies with stormwater and recycled water.  Ratepayers will have to pay back this loan on  their water bill.  The city needs to keep the remaining $66M of unallocated settlement funds to restore  and sustain one of Santa Monica’s most precious natural resources: our groundwater supply.  Sincerely,  M a r k   G o l d      D a v i d   P e t t i t   Item 9-A 01/09/18 Item 9-A 01/09/18