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6.2.3. Regulation of the Migration of Contaminated Groundwater The RWQCB, Riverside DEH, and other regulatory agencies provide data and information on impacts to groundwater and potential offsite migration of contamination plumes.
Strategies 23 and 24 allow for better coordination with regulatory agencies and identification of areas of contaminated groundwater. Strategies 4 and 5 (involving wellhead treatment of wells downgradient of contaminant sources) directly address one area where groundwater contaminated with certain VOCs has been migrating toward water supply wells.
6.2.4. Administration of a Well Abandonment and Well Destruction Program
Through their Water Engineering Program, Riverside DEH requires that a permit be obtained for the abandonment of any well in the County (Riverside DEH, 2008). Guidance for well abandonment procedures are consistent with the standards developed by DWR for drilling and destroying wells in California (DWR, 1991). In addition, the County provides a registry of approved well drillers who are familiar with County regulations and policies. The publication of such a list increases the likelihood that permits and proper well abandonment procedures will be followed. Strategy 23 involves increased coordination with the Riverside DEH Water Engineering Program and well abandonment procedures.
6.2.5. Mitigation of Overdraft Conditions
As indicated by the preliminary water balances for the Temescal and Coldwater subbasins, both areas have experienced overdraft conditions over the Study Period. From 1990 through 2004, Coldwater Subbasin experienced overdraft conditions with an estimated loss of about 20,000 AF of groundwater storage over the 15-year period. However, the water balance indicates that conditions were improving at the end of the Study Period because of decreased pumping rates in the subbasin. The City is working with other subbasin pumpers to control overdraft conditions through pumping limitations. Strategy 9 provides for an evaluation of enhanced recharge in Coldwater Subbasin.
The water balance in Temescal Subbasin indicates that overdraft conditions occurred in the last three years of the Study Period as average pumping increased from about 10,000 AFY to almost 20,000 AFY. Given the uncertainty associated with imported water amounts in the future, the City will need to rely on the groundwater subbasin for a substantial amount of its water supply. This indicates that control of overdraft conditions through pumping limitations alone may be unrealistic. As such, the City is including numerous strategies for managing groundwater while maintaining groundwater production.
Strategies 1 through 3 include new wells that will allow flexibility in pumping distribution and maintenance of water levels. Strategies 10, 11, 12, and 13 provide for enhanced recharge directly into the Temescal Subbasin. Strategies 9 and 18 provide for increased recharge
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6.2.6. Replenishment of Groundwater Extracted by Water Producers For this Study Area, the replenishment of groundwater extracted by pumpers in the basin is the same issue as the mitigation of overdraft conditions discussed above with a focus on Temescal Subbasin. As previously discussed, the replenishment of Coldwater Subbasin can likely be obtained with natural recharge over time if pumping reductions are in place. For Temescal Subbasin, enhanced recharge is more critical given the current and planned reliance on the subbasin for water supply. Strategies 10, 11, 12, and 13 are the most important strategies for replenishment with Strategies 14, 15, and 21 to provide the supporting infrastructure.
6.2.7. Monitoring of Groundwater Levels and Storage
Strategy 8 provides for the adoption of a monitoring program and protocols and a commitment for improved monitoring components in the future. The current monitoring program and protocols are described in Appendix B. Also included are recommendations for future improvements to the program.
6.2.8. Facilitating Conjunctive Use Operations
To provide for the efficient use of all water sources including groundwater, imported water, and recycled water, the City is interested in the construction and operation of several conjunctive use facilities. Strategies 9, 10, and 11 rely on existing detention basins or permeable off-stream sites for conjunctive use of surface water, imported water, and/or recycled water. In particular, Strategies 10 and 11 seem implementable with relatively minimal land acquisition and recharge basin construction costs. Strategies 12 and 13 involve the construction of injection wells that could use imported water or recycled water to replenish groundwater, especially during the winter months when excess water may be available. Collectively, these strategies provide for key conjunctive use facilities to be constructed and operated by the City.
6.2.9. Identification of Well Construction Policies
Since 1949, DWR has been given the responsibility for developing well standards for the purpose of water quality protection (DWR, 1991). Standards for the construction and destruction of water wells were first published in 1968 and updated in 1974 (DWR, 1981). Subsequent amendments to the Water Code required the development of minimum standards for monitoring and cathodic wells in addition to water wells. Bulletin 74-91 sets those standards as minimum requirements by local agencies. A permit filed in the form of a Well Completion Report/Driller’s
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6.2.10. Construction and Operation of Groundwater Contamination Cleanup, Recharge, Storage, Conservation, Water Recycling, and Extraction Projects
Strategies for groundwater management involve each of the components listed in this item with the exception of water conservation, which is being addressed separately by the City as summarized in previous sections of this document and described in the City’s Urban Water Management Plan (AKM, December 2005). Strategies 4 and 5 provide for migration control of a VOC plume of contaminated groundwater and mitigation of water quality impacts to City wells.
Strategies 9 through 13 and 18 describe recharge projects for increasing groundwater storage.
Strategies 13 through 19 address the expanded and efficient use of recycled water. Strategies 1, 2, 3, and 5 provide for more flexibility in groundwater extraction through varying pumping distribution within the aquifer to manage levels and quality.
6.2.11. Development of Relationships with State and Federal Regulatory Agencies
Strategies 23 and 24 specifically address coordination with key regulatory agencies on groundwater management activities. Coordinated management focuses on water quality issues as regulated by the RWQCB and Riverside DEH and well construction/abandonment policies regulated by Riverside DEH and DWR.
6.2.12. Review of Land Use Plans and Coordination with Land Use Planning Agencies to Assess Activities which Create a Reasonable Risk of Groundwater Contamination
The City of Corona is close to build out with little opportunity for major changes to land use planning. Nonetheless, the Department of Water and Power can communicate closely with City planners on the vulnerability of the groundwater resource and protection measures for risk assessment. In the City’s General Plan, adopted in March 2004, the City established a goal and related policies to manage urban runoff for protection of groundwater. Policies address the proper handling, storage, application, and disposal of pesticides, insecticides, and similar substances.
Policies also address stormwater management and reuse and BMPs from construction.
6.3. Evaluation of Management Strategies
Several of the identified groundwater management strategies were evaluated with the groundwater flow model constructed as part of this GWMP. The evaluation and results are
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*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV discussed in the following sections. Details on model construction, calibration, and setup for application of the management strategies are provided in Appendix C. Figures C-11 through C-14 summarize changes in water levels in the target wells associated with the baseline evaluation and management strategies as described in the sections below.
6.3.1. Baseline Evaluation
To provide a baseline against which to measure groundwater management strategies, a baseline model run was developed that accounts for a total demand at build out of about 51,631 AFY. As previously discussed, the City has a tentative target for obtaining one-half of the demand from the groundwater subbasins, or a total pumping amount of 25,816 AFY. The Coldwater Subbasin appears capable of providing at least 3,500 AFY (equal to the City’s 2007 pumping). Pumping in Bedford Subbasin could potentially provide another 600 AFY, leaving a demand of about 21,700 AFY from the Temescal Subbasin. Additional details of the baseline scenario are provided in Appendix C.
Modeling indicates that baseline pumping results in average water level declines of about 30 to 50 feet in the main portions of the Channel Aquifer over the simulation period. These declines would result in dewatering of more than 50 percent of the aquifer thickness in some wells, substantially decreasing well capacity.
The decline also represents a substantial loss of groundwater in storage in the unconfined aquifer. A summary of the average water budget components under baseline conditions is provided in Table 6-2.
Table 6-2
Baseline Evaluation Water Balance (AFY)
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TOTAL INFLOWS (AFY) 18,377
OUTFLOWS
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6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 27,203
Change in Storage -8,826
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6.3.2. Scenario 1 - Pumping Redistribution
To evaluate the impact of redistributing pumping within the Channel Aquifer, two new downgradient wells were simulated in this model run. The new wells were positioned to potentially intercept subbasin outflow to the Prado Management Area and were assigned a pumping amount of 2,500 AFY for each well. The baseline pumping total was maintained and pumping amounts were systematically decreased in current production wells to account for the added production in the new wells.
The water budget from this model run is summarized in Table 6-3. As shown in the table, the outflows are similar to the baseline simulation, but inflows have decreased (compare 18,377 AFY in Table 6-2 to 18,122 AFY in Table 6-3). As such, the average storage decline of -9,095 AFY is slightly worse than under baseline conditions due to the slight decrease in inflow from Arlington Gap. This occurred because decreased pumping in upgradient wells resulted in rising water levels and decreasing gradients across the gap. In addition, the new pumping was not sufficient to decrease basin outflow, which resulted in almost the same average outflow total as simulated under baseline conditions (compare outflows in Table 6-3 to Table 6-2). Annual results from the Scenario 1 simulation are provided in Appendix C in Table C-4.
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Table 6-3
Scenario 1
Pumping Redistribution Water Balance (AFY)
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TOTAL INFLOWS (AFY) 18,122
OUTFLOWS
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6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,475
TOTAL OUTFLOWS (AFY) 27,217
Change in Storage (AFY) -9,095
Although the decline in storage was greater, Scenario 1 was successful at increasing water levels in most target wells from baseline conditions (see Figures C-11 through C-14 in Appendix C). By the end of the 15-year simulation period, water levels had risen an average of about 10 feet in key wells. This is expected, given that most of the calibration targets are active pumping wells and any decrease in pumping will result in a rise in water levels. Nonetheless, this simulation suggests the water levels can be maintained on a short-term basis through redistributions in pumping.
Several additional model simulations were conducted with additional downgradient pumping wells to capture basin outflow to the Prado Management Area. Results of these runs are not included in the GWMP, but indicated that substantial increases in pumping just upgradient of the Prado Management Area were not capable of capturing large percentages of the outflow. It is not clear whether boundary conditions limit the model’s ability to simulate the capture of outflow or whether most of the outflow is not occurring near the area of simulated wells. Additional analyses will be required to further evaluate the optimal location and number of wells for decreasing outflow and increasing basin yield.
6.3.3. Scenarios 2 and 3 - Enhanced Recharge at Detention Basins As previously discussed, pilot testing conducted by the City at the Oak Avenue and Main Street detention basins noted high infiltration rates and indicated that up to about 6,500 AFY could be recharged with construction of spreading basins within each larger detention basin
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(about 5,000 AFY in Oak Avenue Basin and about 1,500 AFY in Main Street Basin). The source of the recharge water would most likely be a combination of recycled water and stormwater.
Imported water could also be used if available. Since current draft regulations regarding the recharge of recycled water call for dilution with another source, a combination of source waters will likely be needed. Actual implementation of this strategy would require coordination with regulatory agencies, including RCFCWCD, monitoring, and in-basin cleanup.
For simulation in the groundwater model, it is assumed that one-half of the recharge water is from water available only during the wet season. Recycled water is recharged year-round in the simulation. Recharge at the two basins was simulated separately for evaluation. Baseline pumping was used. Wastewater discharge to percolation ponds was slightly decreased reflecting the use of recycled water. Details of the simulations are provided in Appendix C.
The results of the model water budgets are summarized in Tables 6-4 and 6-5 for the Oak Avenue Detention Basin and Main Street Detention Basin recharge scenarios, respectively. Both scenarios show less groundwater storage declines than baseline scenarios because of the increase in inflows, equivalent to the amount of recharge assigned to each scenario. Because a larger volume of water was recharged at Oak Avenue, that scenario shows the most improvement.
Declines in groundwater storage were -4,309 AFY and -6,562 AFY for Oak Avenue and Main Street basin recharge, respectively. This compares to the average decline in groundwater storage of -8,826 AFY under baseline conditions. Annual results for the two simulations are provided in Appendix C on Tables C-5 and C-6.
In general, water levels did not respond significantly to the smaller amount of recharge in the Main Street Detention Basin over a 15-year simulation period. Water levels rose about 16 feet on the alluvial fan in response to the larger recharge amounts in the Oak Avenue Detention Basin.
In addition, water levels also rose several feet in the Channel Aquifer under this scenario. Water level hydrographs in target wells are provided in Appendix C.
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Table 6-4
Scenario 2
Recharge at Oak Avenue Basin Water Balance (AFY)
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TOTAL INFLOWS (AFY) 22,890
OUTFLOWS
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6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 27,199
Change in Storage (AFY) -4,309
Table 6-5
Scenario 3
Recharge at Main Street Basin Water Balance (AFY)
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TOTAL INFLOWS (AFY) 20,642
OUTFLOWS
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TOTAL OUTFLOWS (AFY) 27,204
Change in Storage (AFY) -6,562
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6.3.4. Scenarios 4a and 4b - Upgradient Injection Wells in Channel Aquifer Currently, 5 MGD to 10 MGD could be dedicated to a recharge well project during the wet season (2,762 AF to 5,524 AF over six months). Assuming an injection well capacity of about 1,000 gpm, approximately four wells to seven wells would be needed for the recharge of recycled water. As such, two scenarios were evaluated in the groundwater model: four wells recharging 2,762 AFY and seven wells recharging 5,524 AFY (with recharge occurring over a six month period). Wastewater discharge is also decreased to reflect the treatment of additional wastewater for recycled water production. To provide benefits to downgradient wells, the preliminary location selected for the injection wells was the most upgradient position in the Channel Aquifer, near Arlington Gap. Additional details on the simulation of the injection wells are provided in Appendix C.
The results of the scenarios are summarized by the model water budgets presented in Tables 6-6 and 6-7. (Annual results are provided in Appendix C on Tables C-7 and C-8). In both cases, the average subbasin inflows are higher than estimated for baseline conditions, reflecting the increased recharge. As shown in the tables, total inflows are estimated at 20,987 AFY and 21,068 AFY for the injection well scenarios compared to average inflows of 18,377 AFY for the baseline scenario. However, the increase in inflows was not equivalent to the amount of recharge added because of decreases in other inflow totals including less subsurface inflow at Arlington Gap. The locations of the injection wells create water level rises near the gap and block a certain portion of the inflow. Additional evaluation is necessary to optimize the location of the injection wells. Nonetheless, the storage decline associated with these two scenarios is less than under baseline conditions. Water level hydrographs showing the change in water levels at the end of the 15-year simulation period for both injection well scenarios (Scenarios 4a and 4b) are provided in Figures C-11 through C-14 in Appendix C.
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Table 6-6
Scenario 4a
Recharge near Arlington Gap (4 wells) Water Balance (AFY) INFLOWS
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5HFKDUJHIURP:DVWHZDWHU'LVFKDUJH 9,390
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5HFKDUJH:HOOVDW$UOLQJWRQ 2,762
TOTAL INFLOWS (AFY) 20,987
OUTFLOWS
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6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 27,199
Change in Storage (AFY) -6,212
Table 6-7
Scenario 4b
Recharge near Arlington Gap (7 wells) Water Balance (AFY) INFLOWS
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5HFKDUJHIURP:DVWHZDWHU'LVFKDUJH 7,988
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5HFKDUJH:HOOV 5,524
TOTAL INFLOWS (AFY) 21,068
OUTFLOWS
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6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 27,195
Change in Storage (AFY) -6,127
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In addition to improving changes in groundwater storage, these two recharge scenarios also benefit water levels throughout the Channel Aquifer. Water levels rose more than 25 feet in some upgradient areas near the injection wells. As expected, water levels rose more in upgradient wells, but even some downgradient wells recorded water level rises of about 8 feet over baseline conditions (Figures C-11 through C-14, Appendix C).
In summary, the management strategy of recharge wells improved water levels and water budgets, but decreased Arlington Gap inflow. Recharge wells offer the best potential for direct and immediate recharge to the Channel Aquifer, but additional evaluation will be necessary to determine optimal locations and number of wells.
6.3.5. Recycled Water Recharge
As described in the management strategies above, enhanced recharge will be needed for management of the groundwater subbasins. Given recent uncertainties in the reliability of SWP and other sources of imported water, recycled water may be the City’s most reliable supplemental supply for groundwater recharge. To ensure that groundwater quality is not adversely impacted from the recharge of recycled water, a preliminary review of 2007 recycled water quality data was conducted. Prior to implementation, recycled water recharge projects will be further evaluated to ensure compliance with recharge regulations and permit requirements.
Water quality data from the 2007 monitoring program was compared against the primary and secondary MCLs for regulated compounds relevant in draft recycled water recharge regulations (California DPH, 2007). Because the City is not currently recharging recycled water, not all of the regulated constituents have been analyzed to date. In particular, radionuclides and an expanded list of organic chemicals will be analyzed as recycled water recharge is further evaluated. Additional unregulated constituents may also require analysis.
A review of the 2007 monitoring data demonstrates that all but one constituent (TDS) analyzed in the City’s recycled water already meet relevant regulatory standards. The recycled water TDS concentration of 650 mg/L does not meet the secondary recommended MCL of 500 mg/L, but is significantly below the maximum permitted of 1,000 mg/L. Because the City’s wastewater is a blend of groundwater and imported water (with lower TDS), the concentration of TDS in wastewater is generally lower than in groundwater, resulting in a benefit to the subbasin.
DPH regulations allow recharge of TDS concentrations higher than 500 mg/L under certain conditions. Final permitted levels will be determined as the project moves forward.
Only one regulated organic compound, chloroform, has been detected in the City’s recycled water. This chemical is typically formed as a disinfection byproduct after chlorination has been used to ensure extinction of microbial pathogens. The compound was detected at only a trace value and is more than two orders of magnitude below the MCL. Given the data reviewed to date, the recharge of recycled water is not anticipated to adversely impact groundwater quality.
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6.4. Recommended Management Strategies
As indicated in the evaluations above, no single strategy will achieve BMOs. A combination of strategies will be required, especially those supporting enhanced recharge and inlieu pumping. Without management strategies, the groundwater subbasins will not be sustainable at the pumping rates identified as being needed at build out. Management strategies will be conducted in concert with continued water conservation strategies to manage demand.
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7. Implementation Plan
In development of an implementation plan for the management strategies identified, issues such as funding opportunities, budgeting, and need are considered. Several of these programs are ongoing and are required for continued operation of the water supply. In addition, several of the strategies rely on the implementation of other strategies. Information on the prioritization of projects and the implementation are provided below.
7.1. Prioritization of Strategies
Given the results of the water balance and the need for increased groundwater development, the highest priority for groundwater management are strategies that provide for enhanced recharge (or in-lieu pumping) in the groundwater basin. The best use for imported water at this time seems to be direct use, especially if the availability allows for an offset in pumping. The most reliable supply for recharge is likely to be recycled water. However, for the expanded use of recycled water, additional conveyance and infrastructure improvements are required, namely, Strategies 14 and 15 (Interconnect Recycled Water Zone 3 to Zone 2 and Interconnect Recycled Water Zone 4 to Zone 3).
7.2. Implementation Plan and Schedule
Capital improvement projects and corresponding implementation schedule are summarized in Table 7-1. These projects, designated C-1, C-2, etc., correspond directly to the strategies described in Chapter 6 (C denotes a capital improvement project). The remaining management strategies not listed in Table 7-1 include Strategy 19 (Use of Recycled Water as InLieu Pumping), 23 (Coordination with Riverside DEH), and 24 (Coordination with RWQCB).
The coordination efforts will begin immediately and build on current relationships with the agencies. Strategy 25 (Water Conservation and Demand Management) is ongoing and will continue as a coordinated effort with the City’s Water Conservation Coordinator. The use of recycled water as in-lieu pumping (Strategy 19) is also ongoing and will be expanded as additional markets are identified.
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Table 7-1
Implementation Plan and Schedule
Project
Number Project Description
Annual
Water Yield
(AF)
Project
Cost Year
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7.3. Annual Re-evaluation of Management Performance
The implementation of groundwater management strategies and the performance of management activities will be reviewed on an annual basis. A close assessment of the basin response to operational changes and pumping re-distribution among existing wells will provide additional information on management. Ongoing improvements to the monitoring network will also allow for a more detailed evaluation of groundwater levels, quality, and storage.
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8. References
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882
PRESS RELEASE
June 5, 2008
For Immediate Release
Contact: Matthew Bates, Utility Engineer, (951) 279-3692 Corona Groundwater Management Plan
As part of the City’s on-going efforts to efficiently manage its finite water resources, the Corona Department of Water and Power contracted with AKM Consulting Engineers and Todd Engineering in January 2006 to prepare an Assembly Bill 3030 compliant Groundwater Management Plan (GWMP). The Plan recommends approaches the City can utilize to increase the efficient usage of its groundwater to ensure its availability in the future.
AKM Consulting Engineers and Todd Engineering recently completed the Plan and the Department of Water and Power will recommend its adoption at the City Council meeting on June 18th, 2008 at 7:00 p.m. in Council Chambers.
If you have any questions or require additional information regarding the Plan, please contact Matthew Bates, Utility Engineer at (951) 279-3692. #####
(951) 279-3692 730 Corporation Yard Way Corona, California 92880
DEPARTMENT OF WATER & POWER
“Protecting Public Health”
General Manager’s Office
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Contact
Table A-1
List of Potential Stakeholders
City of Corona Groundwater Management Plan
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV Appendix B – Monitoring Program and Protocols
B-1 Introduction
One of the groundwater management strategies (Strategy 8) presented in this GWMP is an improved groundwater monitoring program capable of characterizing groundwater conditions in the subbasins of interest and tracking future changes in water levels, water quality, and groundwater storage. This appendix documents the City’s current monitoring program and makes recommendations for improvements going forward.
B-2 Background
The City has monitored water quality in production wells in the Temescal, Coldwater, and Bedford subbasins to ensure a high quality supply and to comply with regulations over time.
Since 1998, the City has conducted a more formal monitoring program including water level measurements in about 23 production wells and maintaining these data in a water level database.
Data on water levels in City production wells dating back to 1994 have been provided to a consultant for the Santa Ana River Watermaster (Watermaster Support Services). This firm provided these data in a publicly-available database to Todd Engineers in support of this project.
Those data have been combined with other water level data and entered into the City’s Data Management System (DMS) constructed for this GWMP. Although the City water level data were noted as being measured either during pumping or non-pumping (static) conditions, some static measurements have been overly influenced by well drawdowns and indicate that the well had not completely recovered when levels were recorded. In addition, some of the noted pumping water levels appear to correlate more closely to static water levels in other wells. In addition, surveyed reference elevations are not always recorded for a well.
Over the last two years, the City expanded the water level monitoring program to include wells that are not currently pumping (or pump on a limited basis). These wells are a combination of inactive irrigation wells, inactive or periodically-used production wells, and dedicated monitoring wells installed by the City. These data are less influenced by pumping and are more representative of overall subbasin conditions. In connection with this GWMP, the City wishes to document and formalize the monitoring program and consider additional improvements to the program over time.
B-3 Objectives of Monitoring Program
Objectives of the monitoring program include the following:
• characterize water levels and water quality in various aquifers across the subbasins
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV • monitor areas of concern to continue to address specific problems • evaluate the performance of groundwater management activities • track changes in groundwater levels, quality, and storage over time.
The spatial distribution of the monitoring points should focus on key areas based on specific subbasin hydrogeologic conditions. In addition, the program should maintain an element of random locations to allow for the identification of unanticipated changes within the system. To achieve these objectives, protocols of the monitoring program including the locations, measurements, equipment, frequencies, and constituents to be monitored are reviewed below.
This program is evaluated with respect to the hydrogeologic conditions described in Chapter 3 of the GWMP and recommendations are made for program improvements.
B-4 Current Groundwater Monitoring Program
The City maintains a groundwater monitoring program consisting of about 39 wells, 21 of which are active production wells owned and operated by the City for drinking water supply.
The remaining 18 wells are a combination of inactive production wells and wells installed specifically for monitoring groundwater conditions. For the purposes of this discussion, the 18 wells are referred to as monitoring wells and the 21 wells in the City’s system are referred to as City production wells. The selection of monitoring locations has generally been based on the following criteria:
• Availability of unused wells owned by others
• Easy access to wells
• Ability to physically access the well with a sounder or sampling pump/bailer • Well screens across aquifer of interest
• Well location monitors specific activity of interest (e.g., installed for a pilot test for enhanced recharge)
• Network spatially distributed throughout the subbasins of interest.
Wells included in the monitoring program are shown on Figure B-1 with the City’s active production wells identified separately. For the purposes of this discussion, the wells in the monitoring program that are not wells in the City’s active production water system are referred to as monitoring wells. Well data and monitoring components are summarized in Table B-1.
B-4.1. Water Levels
As shown on Figure B-1, the 18 monitoring wells are located in about eight separate locations with more than one well at four locations. Clusters of four monitoring wells are located
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV near City production Well 11, Oak Avenue Detention Basin, and Main Street Detention Basin.
Two wells are located in the eastern arm at Arlington Gap.
The monitoring and production wells in the water level monitoring program are well distributed across Temescal Subbasin and cover most key areas (Figure B-1). Nine of the monitoring wells track water levels in or near the Channel Aquifer along with most of the production wells. Two inactive production wells owned by Home Gardens County Water District allow the City to share water level data. These are key wells located near the Arlington Gap and provide data for the assessment of groundwater storage and the subbasin water balance. In addition, shallow monitoring wells have been drilled in the Oak Avenue and Main Street detention basins in the upland portion of the alluvial fan in Temescal Subbasin.
Water levels at the downgradient extent of Bedford Subbasin are monitored by the irrigation well at Dos Lagos. No dedicated monitoring wells are currently located in the Coldwater Subbasin, but the City is making attempts to locate a former state monitoring well to track water levels there. Currently, water levels in the Coldwater Subbasin are available from City production wells.
Water levels are measured at each of the 18 monitoring wells on a monthly basis. The City uses an electric sounding probe for measuring depth to water in most of the wells. For the Home Gardens Well 5, data are available from a transducer pressure gauge. Depth-to-water measurements are made by City personnel on an established field monitoring form. Also recorded are the status of the well (pumping or not), the date, and the initials of the field person.
B-4.2. Water Quality
Groundwater quality monitoring has occurred at the City’s active production wells, providing extensive water quality data in the Channel Aquifer. To date, no formal water quality monitoring program has been established at the monitoring wells, primarily because of an inability to pump some of the wells. The high concentration of water quality monitoring in the Channel Aquifer is appropriate given the unconfined nature of the aquifer and the City’s reliance on the aquifer for its drinking water supply.
More than 7,400 records of water quality analyses from 1948 through 2004 were compiled for 25 City wells (including historical data from now-abandoned wells) and entered into the GWMP DMS. Currently, groundwater sampling occurs in all active production wells (Table B-1).
The laboratory analyses of groundwater samples include constituents set forth in Title 22 of the California Code of Regulations in compliance with federal standards and state regulations.
These constituents allow for testing of both inorganic and organic chemicals of concern in the subbasins. These data are summarized in Consumer Confidence Reports provided to City water users.
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV B-4.3. Groundwater Storage
Changes in groundwater storage as estimated in this GWMP were based primarily on an assessment of individual water balance inflows and outflows. The resulting change in storage was compared to changes in water levels in production wells for reasonableness. In the future, this assessment can be improved by comparing the water balance results to water level contour maps that depict change in groundwater storage over the entire subbasin based on data from monitoring wells. This assessment removes the near-wellbore effects of pumping from the analysis of changes in water levels over time. The current monitoring program is not sufficient to conduct such a detailed assessment, but the addition of dedicated non-pumping wells to the program is a step in the right direction. Increased monitoring at non-pumping wells, including City wells that have been turned off sufficiently long for water level recovery, will also improve the City’s ability to track changes in groundwater storage over time.
B-5 Surface Water Monitoring Program
Releases to Temescal Wash are monitored by various dischargers through NPDES permit requirements. One active stream gage in the City is monitored by local agencies (11072100, Figure 7 in the GWMP figures). Streamflow data are generally unavailable on Temescal Wash as it enters and exits Bedford Subbasin and as it enters Temescal Subbasin. Improved gaging in these areas could assist in developing a water balance for Bedford Subbasin and improving the water balance analysis in Temescal Subbasin.
As Temescal Wash enters the Prado Management Area, a surface water sampling station is maintained by Orange County Water District. Other stream gage data are available from additional flows into the management area to account for surface outflow at Prado Dam.
Additional streamflow measurements by the City in this area seems unnecessary at this time.
Pool elevation data from the Prado Management Area allow for the assessment of rising groundwater that is considered subsurface outflow from the Temescal Subbasin water balance.
More detailed data likely exist for this area than were compiled for the GWMP. Additional data compiled from this area could allow for a more detailed assessment of basin outflow than estimated from the groundwater flow model in this analysis. The City is in the process of assessing outflow conditions in connection with a hydrogeologic characterization for their wastewater percolation ponds. Data from this study should be incorporated into the DMS for future assessments of subbasin outflow.
B-6 Land Subsidence Monitoring
Excessive groundwater pumping in certain aquifer systems can cause subsurface compaction, resulting in subsidence of the overlying land surface. Land subsidence resulting from overdraft conditions has been documented throughout the state including the Santa Clara Valley
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV and Central Valley of California. The most susceptible systems contain sufficient thickness of semiconsolidated silt and clay layers (aquitards) that can result in a vast one-time release of “water of compaction” (Galloway, et al., 1999). As this water is permanently released from the structure of the fine-grained units, the layers collapse, impacting overlying units and reducing the storage capacity of the aquifer system.
Land subsidence in the form of ground fissuring has been identified in the adjacent Chino Groundwater Basin since the 1970s. The susceptible area is located about 2.5 miles north of the Prado Management Area (WE, 2006). An extensometer and other monitoring techniques have been employed to track land subsidence in this area.
To our knowledge, neither land subsidence nor ground fissuring have been identified as issues in the Temescal, Bedford, or Coldwater subbasins. The absence of thick, fine-grained aquitards in these areas suggest that land subsidence should not be a concern. The Channel Aquifer contains very little fine-grained sediments as confirmed by lithologic logs and the few geophysical logs in the subbasin. Fine-grained units are likely more predominant in the distal portions of the Temescal Subbasin alluvial fan, south and southwest of the City’s current production wells. If the City develops groundwater on the Temescal Subbasin alluvial fan, the potential for land subsidence should be considered. In the Coldwater Subbasin, production wells are located in the proximal and mid-fan portions of a large alluvial fan characterized by coarsegrained sediments. Gravel mining down to 300 feet confirms the nature of these aquifers.
In consideration of these conditions, land subsidence monitoring does not appear to be an issue for the City and is not recommended for expansion of the monitoring program at this time.
The City will investigate any reports of ground fissures and consider ground surface monitoring if land subsidence is identified as a potential concern in the future.
B-7 Recommendations for Monitoring Program Improvements The City will continue to make improvements to their monitoring program as groundwater management strategies are implemented over the next two years. Ongoing efforts include the exploration and identification of additional wells for possible inclusion into the program. In particular, certain non-pumping wells are being researched in the Coldwater Subbasin for increased monitoring there.
B-7.1. Improvements in Spatial Distribution
The monitoring program should be sufficient to characterize water levels and quality throughout the subbasins and focus on key areas where data collection could prove most beneficial. In addition, the program should be scoped to include an element of random spacing to allow for detections of unanticipated changes. One strategy is to target key areas of subbasin inflows and outflows as identified by the subbasin water balance analysis. For the Temescal
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV Subbasin, inflows are evaluated by the wells in Arlington Gap and in the upland detention basins.
Outflow areas are monitored by the wells at Butterfield Park and Corona High School. Additional inflow monitoring would be beneficial in the area where Temescal Wash enters the basin (south of Magnolia Avenue near All American Way) and the area with inflow from Norco (north of City production Well 26). Additional outflow monitoring could be accomplished with an additional well west of the City percolation ponds (in the vicinity of the Rincon Groundwater Treatment Project included in this GWMP as Strategy 3). With regard to the random element of spatial distribution, additional wells are needed on the slope of the alluvial fan to the south of current production wells.
In the Coldwater Subbasin, only production wells are currently available for monitoring.
Since most of the production occurs in the southern half of the subbasin, it would be optimal to secure a monitoring point both in the south near production and in the north away from the wells to evaluate groundwater storage changes in the subbasin. A well just west of the Glen Ivy fault near Coldwater Wash would be most beneficial for also evaluating subsurface outflow across the fault plane. With respect to Bedford Subbasin, no wells currently exist in the southern portion of the subbasin and additional monitoring there would allow for better understanding of the subbasin groundwater system.
It would be helpful to add monitoring wells to the water quality monitoring program as analyses are currently conducted only in production wells. Extraction wells pull in large volumes of groundwater from a large area, which can mix and dilute specific chemicals of concern.
Additional understanding of groundwater quality away from pumping wells would add significant value to the data collection efforts.
These improvements can be accomplished by securing access to existing wells or installation of new monitoring wells. If new wells are constructed, the diameter should be sufficiently large to allow for both groundwater level and quality monitoring.
B-7.2. Expanded List of Constituents for Analysis
For water quality monitoring, the list of constituents should be responsive to how the data are to be applied. For continued characterization of inorganic water chemistry and assistance with determining the source direction for groundwater types, the monitoring program should contain a full suite of cations and anions and a cation/anion balance. This analysis allows for the designation of water types and fingerprinting of groundwater in various parts of the basin. In addition, the analysis is cost effective and adds very little to the cost of monitoring already conducted by the City.
Because of the large number of underground storage tanks over the shallow and unconfined Channel Aquifer, additional constituents should be added to the monitoring program to ensure no impacts from leaking tanks. In particular, total petroleum hydrocarbons, benzene,
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV toluene, ethylbenzene, xylenes, and methyl-tertiary butyl ether (MTBE) should be included.
These analyses should be conducted on all wells for several sampling events to ensure no current impacts. After initial sampling, specific wells could be targeted for continued monitoring of these constituents.
B-7.3. Monitoring Frequency
A review of hydrographs indicates that water levels change seasonally and are most responsive to changes in groundwater pumping. In order to continue to characterize water level changes with monthly pumping patterns, water level monitoring should be conducted on a monthly basis.
Ambient groundwater quality is not expected to vary on a monthly basis and is less susceptible to seasonal changes. As such, annual to semi-annual monitoring seems sufficient for the groundwater quality monitoring program. Exceptions to this include areas where groundwater contamination has been identified as a threat to groundwater quality. These areas should be monitored more frequently to better understand the potential impacts as contaminants migrate downgradient. This increased frequency in monitoring will likely be conducted by the site responsible for the groundwater quality impact and may not result in increased monitoring by the City. However, the City should periodically acquire and review the monitoring data for incorporation into their DMS. Water quality monitoring at the active production wells will continue at the frequencies required for compliance with state regulations for drinking water supply.
B-7.4. Quality Assurance/Quality Control Measures
To ensure that data are properly collected and analyzed, a quality assurance/quality control (QA/QC) plan should be implemented for the monitoring program. This program would provide details on the equipment and sampling procedures for ensuring reliable data. For example, the City should continue and improve the use of monitoring data collection forms for both water levels and water quality. Key details from these forms such as sampling date, time, location, and conditions should be extracted from the forms and input into the City DMS. All water quality sampling should use clean, new containers specific to the constituent to be analyzed. Specific QA/QC samples should be taken (approximately one QA/QC sample per every ten monitoring samples) and all samples should be properly preserved in the field. Water quality sampling should follow standard QA/QC procedures specific to the constituents analyzed. All sampling events should contain a strict chain of custody procedure with proper chain of custody forms completed in the field. State-certified laboratories should be used for analyses. Data should be requested in both paper and electronic format from the laboratories to facilitate updating the DMS and minimize data-entry errors.
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Recommendations for monitoring program improvements are summarized below. • Continue to locate and add wells to the monitoring program with an emphasis on obtaining detailed construction data for any wells added to the program • Increase locations in key inflow and outflow areas to improve the ability to depict changes in groundwater storage
• Add wells in any un-monitored areas of the subbasin to include a random component to the monitoring program
• Expand water quality sampling to monitoring wells
• Analyze water quality samples for a full suite of inorganic constituents to allow for fingerprinting of water types throughout the subbasins • Conduct analyses for a full suite of inorganic chemicals to allow for geochemical plotting techniques for analysis
• Add petroleum hydrocarbon constituent including MTBE to ensure that leaking underground storage tanks have not impacted water quality • Monitor water levels monthly and water quality annually to semi-annually for improved understanding of changes in groundwater conditions • Implement a QA/QC program to ensure data reliability
• Re-evaluate the monitoring programs on an annual basis to determine if additional monitoring points are required or if duplicative data collection efforts can be eliminated.
The monitoring program will evolve over time and be modified for performance monitoring of specific management strategies as implemented. The program should be periodically evaluated to optimize the data collection efforts and achieve monitoring objectives.
State Well Number Well Owner Well Name Well No. Date Well GSE Ref. Elev. Total Top Bottom Water Water Groundwater Drilled Use ft, msl ft, msl Depth ft ft Levels Quality Storage
MONITORING WELLS
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Groundwater Monitoring Data Screen Depth
Table B-1
City of Corona Monitoring Well Program
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A numerical model was developed to assess and quantify the impacts of the management strategies in the Temescal Subbasin described in the Groundwater Management Plan (GWMP), Chapter 6. The model was constructed using data from 1990 through 2004. This Study Period was selected based on hydrologic conditions and climate, as discussed in Chapter 2. Calibration involved testing and changing model variables to better match observed water levels and estimated water budgets. The calibrated model was then used as a foundation for simulating future conditions. The future conditions included the expected buildout pumping, wastewater recharge, and return flows in the model, while repeating previously observed hydrologic conditions (i.e. recharge). This future baseline model was used to compare management scenarios for the Temescal Subbasin.
The groundwater system of the Temescal Subbasin was simulated using the finite difference numerical model, MODFLOW (McDonald and Harbaugh, 1983). Groundwater Vistas 4 was used as a pre and post processor. The model simulated the conceptual model and the water balance described in detail in GWMP Chapter 3.
C-1. Model Area
The numerical model area for layers 1 and 2 are shown on Figure C-1. The model differs slightly from the DWR defined basin (shown in yellow) due to several factors including adjustment of the area based on bedrock outcrops and possible groundwater divides. Specifically, the western and northwestern model area was moved slightly eastward to the contact of bedrock and the more permeable alluvial materials. The groundwater divide identified in Chapter 3 was used as the south model boundary. The Norco area was not included in the model area due to lack of available data. The contribution from the Norco area is simulated as a boundary condition. The model gird was rotated 30 degrees to align with the typical groundwater flow direction in the Channel Aquifer. The grid is made up of 4,470 active cells, each 500 feet by 500 feet. The active area and no-flow cells in the model are shown in Figure C-1. The transient part of the model simulates 1990 through 2004 with monthly stress periods.
C-2. Layers
The numerical model of the Temescal Subbasin is divided into two layers, as shown in Figure C-1. The base of layer 2, the bottom of the model, is defined by the underlying bedrock.
The top of layer 1, the top of the model, is defined by the ground surface elevation from the USGS digital elevation model (DEM) files. The depth of layer 1 was set at the approximate base of the Channel Aquifer, estimated at 450 feet above mean sea level (msl).
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV C-3. Steady State Condition
The model begins with a steady state stress period. The steady state period assures that the initial heads in the model are internally consistent and mathematically sound. The steady state period is roughly based on 1989, a year characterized by little to no change in storage. The initial heads for the steady state condition are based on actual water level data from the late 1980s and early 1990s (Figure C-2). The contours were transformed into a continuous surface using GIS.
C-4. Boundary Conditions
A numerical model seeks to simulate a small portion of a larger system. To represent the interaction of Temescal Subbasin with the larger systems, boundaries were simulated using constant head, general head, and specified flux cells. In most cases, only limited data were available to document the inflow or outflow from these boundaries. The locations and types of boundaries selected are shown on Figure C-3. Changes made to these boundaries during calibration are discussed in the calibration section.
C-4.1. Specified Flux
Subsurface inflow from bedrock was simulated as specified flux along the western (Santa Ana Mountains) and eastern boundaries of the model. Estimates for total flow were derived from recharge calculations used in the water balance, Chapter 3, and adjusted during calibration. As the lag time between precipitation and recharge to the basin is uncertain, a steady state flux, constant over time, was used to simulate inflow. Inflow from the Santa Ana Mountains and the eastern bedrock outcrops was estimated at 721 AFY and 62 AFY respectively.
Inflow from the Norco area of the basin was also simulated as a steady state specified flux. Due to the low permeability in the area, the flow from Norco is expected to be small.
However, the lack of recent water level data in the area made calculations uncertain. A simple flux calculation using Darcy's equation was used to estimate flow at 52 AFY, an amount held constant in the model.
Temescal Creek overlies the Temescal Subbasin in some reaches. The creek is in bedrock in the south, enters the subbasin west of Arlington Gap, and then flows in a concrete-lined channel to the Prado Management Area. The creek’s contribution to groundwater recharge is limited to a small area north of Temescal Canyon as described in Chapter 3. Recharge here is estimated at 113 AFY; as such, this amount is simulated in the model as a specified flux. The monthly distribution ranges from 5 AF/month to 15 AF/month, lower in the summer months and higher during the rainy winter months.
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The inflow or outflow from Arlington Gap was simulated using 14 constant head cells located on the eastern boundary of the model. The level of the constant head for each month was selected using water levels from Home Gardens Wells 3, 4 and Todd_0180 Well (data from SAWPA). Water level measurements from these three wells were infrequent and collected at various times over the Study Period. The water levels from these three wells were combined to compile a complete record of water levels for the constant head boundary. The head at the constant head cells were varied monthly based on available data.
The model-simulated flow across this boundary was compared to flow estimates calculated using Darcy's equation as discussed in Chapter 3. Based on Darcy’s equation, the flow into the basin through Arlington Gap was estimated as a steady annual average of 4,800 AFY.
Using a range of gradients calculated from water levels in nearby wells over the entire period of record, the inflow was estimated to range between 2,225 AFY and 4,880 AFY over the Study Period.
C-4.3. General Head Boundary
The inflow or outflow from the basin through Prado Dam was simulated as a general head boundary, located along the northwestern boundary of the model. Interaction between the Santa Ana River and the Temescal Subbasin was assumed to be a no–flow boundary. The conductance of the general head boundary was adjusted during calibration. The water level of the general head boundary was derived from the elevation of the reservoir behind Prado Dam. These elevation data are available from 1999 to the present from the California Data Exchange Center.
The average monthly elevation of the reservoir was used for the study period. During calibration the elevation was increased by five feet to better match water level measurements and outflow estimates. The model simulates annual outflow that varied from 3,944 AFY to 4,123 AFY.
C-5. Recharge
Recharge in the model simulated deep percolation from precipitation, irrigation return flows, wastewater, and stormwater. Areal recharge was based on the analysis prepared for the water balance in Chapter 3, simplified to include 15 zones of recharge representing different soils, land use, and percolation rates. The area of the zones varied over time as land use in the basin changed; the zones for the last year of the model are shown in Figure C-4. The return flows associated with each land use type were added to the rate of deep percolation. Recharge from return flows and deep percolation ranged from 902 AFY in 1996 to 14,269 AFY in 1993.
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV Wastewater was simulated by three cells in the northern part of the basin, shown in purple in Figure C-4. Annual wastewater totals were estimated in Chapter 3 using available data and population estimates from the City. As seasonal or monthly variation information was not available, an annual distribution was derived from the available water use data. It was assumed that months with higher water use (groundwater pumping and imported water) also indicated months with higher wastewater discharge. As such, wastewater percolation is expected to peak in the summer months June through August. The average monthly rate of wastewater recharge was based on the monthly urban water use distribution (Table C-1). The annual wastewater recharge ranged from 3,650 AFY to 9,474 AFY over the Study Period.
Two stormwater detention ponds located along Main Street and Oak Avenue are sources of increased recharge during winter months. The ponds capture excess runoff from the Santa Ana Mountains and detain this water until it can slowly be released to the stormwater system. The ponds are simulated by two recharge cells in the model, shown in light green on Figure C-4. As discussed in Chapter 3, the average annual inflow to the basin from these ponds was approximately 480 AFY. This volume was divided equally between the two ponds during the rainy winter months November through March.
C-6. Pumping
Twenty eight wells were active in the Temescal Subbasin between 1990 and 2004.
Pumping in these wells was simulated in the model using the well package with monthly stress periods. Annual pumping data were available for all wells and monthly pumping amounts were available for some wells. To account for wells or time periods for which monthly pumping data were not available, estimates were derived by using an annual distribution based on use type (Table C-1). The urban monthly pumping distribution was based on the observed annual distribution of pumping wells with monthly data. For agricultural pumping, a monthly distribution was developed using the distribution of evapotranspiration less monthly precipitation over the year. Pumping occurred only in layer 1 in the model. The active wells are shown in Figure C-3 (flux pumping); total pumping ranged from 7,294 AFY to 20,112 AFY.
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Monthly Pumping Distribution
Month Urban Agriculture
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C-7. Aquifer Parameters
Hydraulic conductivity (K) was first estimated in the model and then adjusted through calibration. A total of nine zones of K values were originally defined. After calibration, the zones were simplified to three zones in layer 1 and two zones in layer 2. The layer 1 zones represented the Channel Aquifer, Norco area, and Alluvial Fan with K values of 125 feet/day, 20 feet/day, and 0.5 feet/day respectively. The layer 2 zones included the area directly below the channel and the deeper Alluvial Fan with K values of 60 feet/day and 0.5 feet/day respectively. These zones are shown in Figure C-5. The assumed ratio of horizontal conductivity to vertical conductivity was 10 to 1. A specific yield of 0.2 was selected for Channel Aquifer and 0.1 was used for all other areas.
C-8. Calibration
The conceptual model and water balance discussed in Chapter 3 was simulated as a numerical model. Variables including the volume of bedrock inflow, conductance and elevation of the Prado Dam boundary, hydraulic conductivity, and location of the channel sediments were adjusted to match water levels observed in target wells and the conceptual understanding of the water budget.
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Eight wells were selected as calibration targets, based on available water level measurements over the Study Period and spatial distribution. Target wells are listed below and shown on Figure C-6. The City’s water level monitoring over the Study Period occurred solely in the City’s pumping municipal wells and it is uncertain if these data reflect pumping water levels or static water levels. While pumping wells generally are not included as model targets, a lack of any other consistent or reliable water level data prevented the addition of other targets. No wells with consistent water levels were available in the Alluvial Fan; however limited data were available near the stormwater ponds from Corona Well 27 in 2003. These data indicated water levels near 850 feet msl. Since very little production has occurred during the Study Period in this area, water levels in this area were assumed to be relatively stable. As such, a hypothetical target with constant water levels of 850 feet msl was developed to aid in calibration.
Table C-2
Targets Used in Model Calibration
TODD ID Agency Name Local Name
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The simulated and observed water levels for each target are shown on Figures C-7 and C8. Water level contours at the end of the model simulation, December 2004, are shown on Figure C-9. Generally, simulated water levels showed a reasonable fit to the elevation and trend of observed water levels. Simulated water levels in wells located in the main part of the Channel Aquifer (Corona Wells 8, 11, 15, and 19) match the elevation and trends of the observed water levels. Simulated water levels on average are slightly higher than observed (by less than five feet).
The observed water levels may be reflecting pumping water levels and not static water levels in the area. Simulated water levels in the target located on the edge of the northern portion of the channel, Corona Well 14, were similar to observed water levels.
Simulated water levels in the target located on the southern edge of the channel, Corona Well 13, are slightly lower than observed (about 10 feet). However, the simulated water levels match the overall trend of the observed water levels. Corona Well 13 is located near the outflow of Temescal Wash, an area of observed high water levels. This area is likely to be significantly
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Home Gardens Well 3 was included as a target, however, its close proximity to the constant head cells simulating Arlington Gap controlled the simulated water levels. The well was left as a target to check on the specified head of the boundary, rather than as an indication of model fit.
The final target was based on limited data from Corona Well 27. Data from this well were available only from March to October 2003. A constant water level of 850 feet msl over the entire time period was used to check the model fit in the area. The target showed a difference of about 13 feet between the simulated and estimated water levels. This difference is due, in part, to the constant water level estimated from limited data. The simulated water levels showed variation over the study period including a decline near the end of the time period.
A comparison of observed to simulated water levels is shown on Figure C-10. Ideally, simulated and observed water levels would fall along the 1:1 trend line on the chart. Overall, the observed water levels show more variability than the simulated water levels. This variability is most likely caused by pumping in or near the target wells. This local effect of pumping on the water levels is not simulated in the model. Simulated water levels tend to be lower than observed in higher elevations and higher than observed in lower elevations. This relationship could be the result of the channel sediments simulated as one hydraulic conductivity zone. Specifically, the model does not simulate the complex geology and the thinning of the channel along the edges.
Again, many of the wells used as targets are production wells, so measured water levels may reflect a pumping water level rather than a static water level. The target on the alluvial fan was not included on this chart as the observed targets were estimated and not based on actual measurements.
C-8.2. Budget
In addition to targets, the overall water budget was evaluated during calibration. The simulated budget, derived from the “reach report” output in Groundwater Vistas, was compared to the conceptual water balance described in Chapter 3. The conductance of the Prado Dam outflow and the hydraulic conductivity of the channel sediments were adjusted to better match the conceptual water balance as well as water levels.
C-9. Sensitivity Analysis
During calibration, the model response to changes of each variable was evaluated seperately to determine its relative sensitivity. As described below, the model results were
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV determined to be sensitive to 1) estimated conductivity and location of the Channel Aquifer, 2) hydraulic conductivity of the Alluvial Fan materials, and 3) the general head boundary at Prado Dam. The location and hydraulic conductivity of the channel sediments (particularly the southern extent of the channel) was found to control local and regional water level elevations. Hydraulic conductivity for the channel sediments were adjusted from 200 feet per day to 100 feet per day.
Using a K value of 200 feet/day resulted in water levels that were consistently 10 to 20 feet higher than those simulated with a K value of 125 feet/day. Water levels in the model, specifically at selected targets, were sensitive to the southern extent of the channel sediments. The location of the high K zone was adjusted to better fit the observed data. While the southern extent of the channel differs slightly from the original geologic interpretation, the width and depth of the channel is uncertain. The model-simulated location of the channel is consistent with the overall geologic understanding of its formation.
Water levels in the Alluvial Fan were very sensitive to the hydraulic conductivity of the area. Various K values were simulated in the area ranging from 0.5 feet/day to 50 feet/day. Using high K values resulted in lower water levels at the hypothetical well in the Alluvial Fan area (567 feet msl using 10 feet/day, compared with 837 feet msl using 0.5 feet/day). Higher K in the alluvial fan resulted in slightly lower water levels in the channel area, a decrease of 3 feet when the K value was adjusted from 0.5 feet/day to 10 feet/day.
Because Prado Dam is the primary outflow of groundwater from the basin (aside from pumping), the volume of outflow was sensitive to the conductance of the general head cells representing Prado Dam. A higher boundary conductance increased the outflow and decreased water levels in the channel. The conductance was adjusted during calibration to obtain a good match with water levels and the expected outflow from Prado, on the order of thousands of AFY.
Conductance was adjusted over a range of 1,000 feet/day to 200,000 feet/day.
Less sensitive variables included the seasonal variation of water levels at Arlington Gap, hydraulic conductivity of the area north of the channel, inflow from bedrock on the eastern edge of the model, and inflow from Temescal Wash.
C-10. Model Limitations
The limited availability and accuracy of data in the Temescal Subbasin constrains the ability to develop detailed conceptual and numerical models. Overall, the numerical model is a good simulation of the conceptual model, but both the conceptual and numerical model can be improved with additional data and understanding of the basin. Possible improvements include consistent static water level monitoring across the entire subbasin, more information on geology and faulting along the western edge of the model, frequent monitoring at the boundaries
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(Arlington Gap, Prado Dam, Chino, Norco), and detailed information on the inflow from the stormwater basins.
The model was designed to simulate the basin on a regional scale and should not be used to examine local issues such as well drawdown or solute transport. The model can be used to compare and relatively quantify management alternatives on a regional scale.
C-11. Management Scenario Application
C-11.1. Baseline
The numerical model calibrated to the 15-year Study Period, 1990-2004 was used as the foundation for a baseline model that simulates future conditions at build out. The 15-year future simulation repeats the hydraulic conditions observed over the Study Period, including the rate of recharge. Land use from 2004 was used to develop recharge zones in the baseline model to better simulate a developed urban area and the amount of return flows and deep percolation from precipitation.
Boundary conditions were also adjusted to simulate expected future conditions. The water levels from Home Gardens Well 3 from 1990 to 2004 were repeated over the 15-year simulation to represent the range of observed conditions at that Arlington Gap boundary. The future water levels at this boundary are uncertain as groundwater management on the Arlington side of the boundary has a large influence on the water levels and therefore flow into the basin.
The height of the Prado Reservoir was also repeated over the 15-year period, and the boundary conductance was held constant.
Expected pumping at buildout, 21,726 AFY, was used for each year of the baseline model. (Rounding of model output resulted in numbers of 21,722 AFY to 21, 725 AFY being displayed in report tables). The increase in pumping over 2004 amounts was distributed among wells based on the 2004 pumping distribution (with small changes to prevent simulated dry cells in the model). Pumping from Wells 25 and 9 were decreased slightly and pumping in Well 17 was increased slightly. Estimated wastewater recharge at buildout is expected to be about 16,350 AFY, based on population projections in the City’s General Plan (2003) and the Water Master Plan (AKM, April 2005). Current irrigation demand for recycled water is approximately 5,600 AFY. In addition, an outflow to Prado Dam of approximately 2,240 AFY (adjusted for water quality) is required. Subtracting these two demands from total wastewater leaves a total of about 8,510 AFY, an amount repeated over the baseline model to represent levels of recharge at the percolation ponds. (Again, rounding of model output numbers resulted in the small variation of numbers included in report tables). Other recharge components such as bedrock inflow and Temescal Wash inflow remained constant.
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV The baseline model was used to simulate management scenarios. Changes made to the model for each scenario are discussed below.
C-11.2. Scenario 1: Pumping Redistribution
This scenario redistributed pumping in the aquifer. Two new wells were added in the northwestern part of the channel, near Prado Management Area. These wells were simulated as pumping 2,500 AFY each and the remaining 16,742 AFY of buildout pumping was distributed among the existing wells based on the same proportion as used in the baseline model. Aside from the well package, no other changes were made to the baseline numerical model for Scenario 1.
C-11.3. Scenario 2: Additional Recharge at Oak Detention Basin This scenario examined additional recharge in the Oak Avenue Detention Basin and a slight reduction in wastewater recharge. The Oak Avenue Detention Basin recharge (simulated in the recharge package) was increased to 5,000 AFY. Wastewater flows, also simulated in the recharge package, were decreased to 8,250 AFY to reflect the use of recycled water for one-half of the enhanced recharge water. The distribution of monthly wastewater recharge was maintained.
No changes were made to the well package (including bedrock inflows or pumping).
C-11.4. Scenario 3: Additional Recharge at Main Street Detention Basin
This scenario, similar to scenario 2, examined additional recharge in the Main Street Detention Basin and an increase in wastewater recharge. The Main Street Detention Basin recharge was increased to 1,500 AFY. Since recharge with recycled water was not as high in this scenario, wastewater flows were increased from Scenario 2. In addition, it was assumed that the outflow to Prado Management Area could be maintained through subsurface outflow and wastewater recharge was increased to the current permit amount of 9,520 AFY recharge at the percolation ponds, using the same monthly distribution (rounding results in an average of 9,507 AFY). No changes were made to the well package (including bedrock inflows or pumping).
C-11.5. Scenario 4a: Recharge wells near Arlington Gap (4 wells) This scenario examined the addition of recharge wells near Arlington Gap. It was determined that approximately 5 mgd of recycled water could be dedicated to recharge wells during the non-irrigation season. Four wells, recharging a total of 2,762 AFY (5 mgd over six months of recharge), were simulated near the eastern boundary of the model. Wastewater recharge at the percolation ponds were increased from baseline to 9,369 AFY, while maintaining the same monthly distribution. Extraction pumping remained the same as baseline.
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$%*URXQGZDWHU0DQDJHPHQW3ODQ 3DJH $.0&RQVXOWLQJ(QJLQHHUV C-11.6. Scenario 4b: Recharge wells near Arlington Gap (7 wells) This scenario is similar to scenario 4a; however a total of seven recharge wells were used to recharge near the Arlington Gap. The amount of recharge was 5,524 AFY (10 mgd over six months). In this scenario wastewater recharge at the ponds were decreased to an average of 7,988 AFY, assuming that a portion of that water would be dedicated to recharge. Extraction pumping remained the same as baseline.
C-11.7. Results
Chapter 6 includes discussion of these management scenarios that were simulated using the numerical model. The water levels and budgets of each scenario were compared to the baseline model and the effectiveness of each management scenario is discussed. Tables with water budgets on an average basis for each management scenario are provided in Chapter 6. The complete water budgets for the baseline model and the five scenarios are provided here in Tables C-3 through C-8. Water levels for the baseline evaluation and the five scenarios at the eight targets are shown in Figures C-11 through C-14.
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
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TOTAL INFLOWS (AFY) 17,997 18,096 17,316 29,889 15,636 18,491 15,862 16,786 20,744 17,417 16,973 17,835 18,659 16,659 17,297 18,377OUTFLOWS *URXQGZDWHU3XPSLQJ 21,7226XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 28,196 27,733 27,454 27,325 27,236 27,157 27,104 27,059 27,037 27,005 26,976 26,953 26,956 26,936 26,917 27,203CHANGE IN STORAGE (AF) -8,826 Table C-3
Baseline Simulation
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
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TOTAL INFLOWS (AFY) 17,982 18,016 17,175 29,695 15,411 18,242 15,590 16,497 20,434 17,096 16,643 17,493 18,310 16,307 16,937 18,122OUTFLOWS *URXQGZDWHU3XPSLQJ
21,742
6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU
5,475
TOTAL OUTFLOWS (AFY) 28,221 27,751 27,472 27,343 27,261 27,175 27,120 27,076 27,059 27,021 26,989 26,965 26,971 26,935 26,898 27,217CHANGE IN STORAGE (AF) -9,095 Table C-4
Scenario 1: Pumping Redistribution
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
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TOTAL INFLOWS (AFY) 22,548 22,153 21,850 34,425 20,196 23,030 20,399 21,327 25,307 21,960 21,513 22,378 23,222 21,200 21,839 22,890OUTFLOWS *URXQGZDWHU3XPSLQJ 21,718 6XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 28,196 27,733 27,454 27,325 27,236 27,157 27,104 27,059 27,037 27,005 26,976 26,953 26,956 26,936 26,853 27,199CHANGE IN STORAGE (AF) -4,309 Table C-5
Scenario 2: Enhanced Recharge at Oak $YHQXH Basin
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
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TOTAL INFLOWS (AFY) 20,295 20,384 19,597 32,164 17,910 20,756 18,117 19,044 23,004 19,671 19,228 20,085 20,915 18,906 19,543 20,64OUTFLOWS *URXQGZDWHU3XPSLQJ 21,7226XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU
5,481
TOTAL OUTFLOWS (AFY) 28,196 27,733 27,454 27,325 27,236 27,157 27,104 27,059 27,037 27,013 26,976 26,953 26,957 26,937 26,917 27,204CHANGE IN STORAGE (AF) -6,562 Table C-6
Scenario 3: Enhanced Recharge at Main St Basin
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
INFLOWS
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5HFKDUJH:HOOVDW$UOLQJWRQ 2,762 TOTAL INFLOWS (AFY) 21,181 20,935 20,024 32,515 18,241 21,069 18,415 19,319 23,252 19,922 19,475 20,334 21,160 19,162 19,795 20,987OUTFLOWS *URXQGZDWHU3XPSLQJ 21,7176XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU
5,481
TOTAL OUTFLOWS (AFY) 28,177 27,733 27,454 27,325 27,217 27,157 27,104 27,059 27,018 27,013 26,977 26,953 26,937 26,937 26,917 27,199CHANGE IN STORAGE (AF) -6,212 Table C-7
Scenario 4a: Arlington Gap Recharge
Wells
Water Year Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8 Year 9 Year 10 Year 11 Year 12 Year 13 Year 14 Year 15 Ave.
INFLOWS
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5HFKDUJH:HOOV 5,524 TOTAL INFLOWS (AFY) 21,785 21,155 20,143 32,589 18,293 21,107 18,443 19,338 23,250 19,930 19,482 20,341 21,175 19,181 19,806 21,068OUTFLOWS *URXQGZDWHU3XPSLQJ
21,7156XEVXUIDFH2XWIORZWR6DQWD$QD5LYHU 5,481
TOTAL OUTFLOWS (AFY) 28,162 27,735 27,456 27,327 27,202 27,159 27,106 27,061 27,003 27,007 26,978 26,955 26,922 26,938 26,919 27,195CHANGE IN STORAGE (AF) -6,127 Table C-8
Scenario 4b: Recharge Wells at Arlington*DS (7 Wells)
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Feasibility Study
Recycled Water Recharge
in Bedford Subbasin
Prepared for:
Lee Lake Water District
22646 Temescal Canyon Road
Corona, CA 92883
Prepared by:
Todd Engineers
2490 Mariner Square Loop, Suite 215
Alameda, CA 94501-1080
May 2008
Table of Contents
1. Introduction ................................................................................................. 1
1.1. Background ................................................................................................ 1
1.2. Goals and Objectives .................................................................................. 2
2. Hydrogeologic Setting ................................................................................ 3
2.1. Study Area .................................................................................................. 3
2.1.1. Subbasin Boundaries .................................................................................. 3
2.1.2. Land Use ..................................................................................................... 4
2.1.3. Subbasin Hydrology ................................................................................... 4
2.2. Geology and Faulting ................................................................................. 5
2.2.1. Geologic Units ............................................................................................ 6
2.2.2. Depth to Bedrock ........................................................................................ 6
2.3. Subbasin Aquifers ...................................................................................... 7
2.3.1. Aquifer Geometry ....................................................................................... 7
2.3.2. Aquifer Parameters ..................................................................................... 7
2.4. Groundwater Use and Wells ....................................................................... 8
2.4.1. Subbasin Production ................................................................................... 9
2.4.2. Domestic Wells .......................................................................................... 9
2.5. Groundwater Occurrence and Flow .......................................................... 10
2.5.1. Water Levels and Depth to Water ............................................................ 10
2.5.2. Groundwater Flow .................................................................................... 11
2.5.3. Groundwater Quality ................................................................................ 12
3. Considerations for Groundwater Recharge ............................................ 14
3.1. Recharge Water Parameters ..................................................................... 14
3.1.1. Quantity Available for Recharge .............................................................. 14
3.1.2. Recycled Water Quality ........................................................................... 14
3.2. Hydrogeologic Considerations ................................................................. 19 )HDVLELOLW\6WXG\//:' L 7RGG(QJLQHHUV
3.2.1. Potential Recharge Methods ..................................................................... 21
3.2.2. Selection of Favorable Areas .................................................................... 23
3.2.3. Groundwater Mounding Estimates ........................................................... 24
3.3. Regulatory Requirements ......................................................................... 26
3.3.1. Distance from Extraction Wells ............................................................... 26
3.3.2. Diluent Water ........................................................................................... 27
3.3.3. Water Quality Requirements .................................................................... 27
3.3.4. Monitoring ................................................................................................ 28
3.3.5. Other Requirements .................................................................................. 28
4. Benefits for Groundwater Management .................................................. 29
4.1. Subbasin Yield ......................................................................................... 29
4.2. Groundwater Quality ................................................................................ 29
4.3. Surface Water ........................................................................................... 29
5. Conclusions and Recommendations ...................................................... 31
6. References ................................................................................................. 33 )HDVLELOLW\6WXG\//:' LL 7RGG(QJLQHHUV
)HDVLELOLW\6WXG\//:' LLL 7RGG(QJLQHHUV
List of Tables Page No.
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1. Introduction
Lee Lake Water District (District) provides water and wastewater services to residents in the Temescal Valley south of the City of Corona. Tertiary treated wastewater from the Lee Lake Water Reclamation Facility (WRF) is currently being recycled for landscape irrigation and other non-potable uses. Excess recycled water is discharged to nearby Temescal Wash in compliance with regulatory requirements. The District is considering recharging the recycled water into the underlying groundwater basin, locally referred to as the Bedford Subbasin.
To evaluate the feasibility of the project, the District retained Todd Engineers to conduct a study of the Bedford Subbasin hydrogeology and evaluate potential recharge options. The location of the Bedford Subbasin and adjacent groundwater basins and subbasins are shown on Figure 1.
In a parallel effort, the District is coordinating with the City of Corona in the preparation of a Groundwater Management Plan (GWMP). The GWMP evaluates three groundwater subbasins within the City’s water service area and recommends strategies for active groundwater basin management. The District’s recharge project has been included in the GWMP as a potential management strategy. Three groundwater subbasins – Temescal, Coldwater, and Bedford subbasins – are included in the GWMP (Figure 1). Plan adoption is scheduled for June 2008.
The City and the District are also cooperating on the environmental review of the GWMP in compliance with the California Environmental Quality Act (CEQA). This process involves the preparation of a Programmatic Environmental Impact Report (PEIR). The District’s recharge project for Bedford Subbasin is included in this review.
This technical memorandum summarizes the analyses and results of the hydrogeologic study and provides support for the GWMP, the PEIR, and the implementation of the District project.
1.1. Background
Lee Lake Water District was formed in 1965 to provide water and wastewater services to a growing population in the Temescal Valley area between Corona and Lake Elsinore (LLWD, 2008). The District currently serves about 4,400 residential and commercial customers within an approximate 10 square mile service area as shown on Figure 2. The City of Corona water service area is located primarily to the northwest, but overlaps a small portion of the District in the Bedford and Coldwater subbasins (Figure 2). Elsinore Valley Municipal Water District (EVMWD) is located south of the District, but also provides some water supply to portions of the Bedford Subbasin (Figure 2). Lee Lake Water District imports )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
their water supply from Western Municipal Water District (WMWD) through the Metropolitan Water District State Water Project (SWP) system. The water is treated at the Mills Filtration Plan in Riverside and conveyed to the District through the Mills Pipeline.
The District also operates several groundwater wells in the subbasin and has historically used groundwater to supplement water supply. Although the wells have only produced a few acre feet per year (AFY) over the last several years, the District maintains these wells for anticipated future production. The District’s project evaluated herein will enhance recharge in the subbasin to support increased future demand.
The District’s wastewater services consist of three wastewater treatment plants:
Butterfield Estates, California Meadows, and the District’s Water Reclamation Facility (WRF). The WRF is located in the northern portion of the subbasin and provides tertiary treatment to reclaim the wastewater for reuse including landscape and golf course irrigation.
Most of the demand for the recycled water occurs during the summer months. Recycled water that exceeds demand is discharged to nearby Temescal Wash. Currently, approximately 700,000 gallons per day (gpd) are discharged in compliance with NPDES Permit No. 8000100, administered by the California Regional Water Quality Control Board, Santa Ana Region (Water Board). The District’s permits allow the expansion of their WRF to a full build-out capacity of 1,570,000 gpd.
1.2. Goals and Objectives
The goal of this evaluation is to identify feasible alternatives for recharge of tertiary treated wastewater into the Bedford Subbasin. The evaluation considered project feasibility on a technical and regulatory basis. Project objectives include the identification of recharge options involving various locations within the subbasin and various recharge methods (e.g., recharge basins or injection wells).
To meet these goals and objectives, Todd Engineers evaluated the hydrogeology of the Bedford Subbasin, assessed the technical feasibility of subbasin recharge, selected areas judged favorable for a recharge project, and identified potential regulatory constraints.
Analyses and results of the study are summarized in this technical memorandum. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
2. Hydrogeologic Setting
The hydrogeologic setting provides the framework for evaluation of the recharge project.
This section summarizes groundwater conditions in the subbasin and presents specific analyses conducted for the project.
2.1. Study Area
The Study Area includes the Bedford Subbasin, covering approximately 6.5 square miles (4,133 acres) of the central Temescal Valley in western Riverside County. The Bedford Subbasin is a relatively small subdivision of the larger Elsinore Groundwater Basin (Figure 1). The Bedford and Coldwater subbasins form the northern portion of the Elsinore Groundwater Basin northwest of a bedrock constriction along Temescal Wash (Figure 1). According to current basin nomenclature used by the California Department of Water Resources (DWR), the Elsinore Groundwater Basin is not formally divided into subbasins (DWR, 2003). The Bedford and Coldwater subbasin nomenclature originates from former DWR basin boundaries in historical documents (DWR, 1959). Since the hydrogeologic conditions, including the bedrock constriction, clearly allow the subbasins to be evaluated separately from the remaining Elsinore Groundwater Basin to the southeast, the nomenclature is preserved in this analysis. Subbasins and contributing watershed areas, as digitized using Geographic Information System (GIS) software, are shown on Figure 1 and summarized on the table below.
Table 2-1
Groundwater Basins and Watersheds
DWR Groundwater Basin*
(Basin No.)
Subbasin** Area
(acres)
Contributing
Watershed (acres)
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2.1.1. Subbasin Boundaries
The Bedford Subbasin is defined by hydrologic and hydrogeologic boundaries. The eastern and southern boundaries are the approximate intersection of alluvial deposits with bedrock outcrops of the El Sobrante de San Jacinto hills (Figure 1). The Coldwater Subbasin lies to the west, separated from the Bedford Subbasin by the North Glen Ivy fault. The fault trace and )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
the subbasin boundary shown on Figure 1 were recently modified from previous historical documents for the City of Corona’s GWMP project. Revisions were based on recent geologic maps from the U.S. Geological Survey (USGS, 2004). On the northwest, the subbasin boundary is defined by the contact between alluvial sediments and the outcropping bedrock of the Santa Ana Mountains. The northern boundary of the Bedford Subbasin is generally defined by the southern edge of Bedford Canyon where the subbasin connects with the Temescal Subbasin of the larger Upper Santa Ana Valley Groundwater Basin (Figure 1).
The subbasin floor is characterized by a narrow sloping valley interrupted by bedrock outcrops and surrounded by uplands. Ground surface elevations range from above 1,300 feet above mean sea level (msl) in the southwest to about 800 feet msl at the northern subbasin boundary near the base of Bedford Canyon. Average ground surface elevations are about 1,000 feet over most of the subbasin. The nature of the land surface can be seen on the aerial photograph on Figure 3. The main drainageway is Temescal Wash (also locally referred to as Temescal Creek), which flows from south to north across the subbasin. Average annual rainfall on the basin is about 13 inches per year (OCS, 2007).
2.1.2. Land Use
The Bedford Subbasin has a rich history as an agricultural area supporting numerous crops including citrus. Through the 1950s and 1960s, almost all of the water use in the subbasin was for agriculture (DWR, 1965). At that time, water supply was a mix of local groundwater, local surface water and imported surface water. In 1954, Western Municipal Water District was annexed to Metropolitan Water District and began providing imported water from the Colorado River (stored at Lake Mathews) to the Temescal Valley (DWR, 1959). In recent years, the I-15 corridor of the Temescal Valley has experienced significant growth. Residential development can be seen on Figure 3 and is especially prevalent west of I-15. Residential communities such as the Retreat, Wildrose Ranch, California Meadows and others have been developed in the area, bringing additional landscaping and golf courses to the subbasin. The community of Dos Lagos has been developed east of I-15 in the northern portion of the subbasin. Commercial and light industrial development occurs along the east side of I-15 in the northern half of the subbasin.
Large portions of the southern subbasin east of I-15 remain relatively undeveloped (Figure 3).
In the adjacent Coldwater Subbasin, residential development has occurred primarily in the northern half of the subbasin. The southern half of the Coldwater Subbasin is dominated by active and inactive sand and gravel mining operations (Figure 3). Both the District and EVMWD provide potable and non-potable water supply for Bedford and Coldwater subbasins.
2.1.3. Subbasin Hydrology
As shown on Figure 3, Temescal Wash is the main surface water drainage for both Coldwater and Bedford subbasins. The Santa Ana Region Water Board Basin Plan lists beneficial uses for the creek as groundwater recharge, water contact recreation, non-contact water recreation, )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
warm water fish habitat, industrial service supply, and agricultural supply. Notwithstanding these designated uses, the creek is typically dry throughout most of the subbasin during the summer.
The creek is tributary to the Santa Ana River and joins the main river channel at the Prado Management Area near Prado Dam (Figure 1).
Temescal Creek receives surface water runoff from contributing watersheds to the east and west (Figure 1). Although the eastern watersheds are slightly larger in area (approximately 11,858 acres) than the western watersheds (9,525 acres), runoff is generally lower. This is due to the lower elevations and lower average annual rainfall of about 13 to 16 inches per year (OCS, 2007; Environmental Solutions, 1994). This amount compares to an average annual rainfall of about 18 to more than 25 inches per year in the higher elevations west of Coldwater Subbasin.
North of the Bedford Subbasin, the creek is fed by surface runoff from Bedford Canyon and rising groundwater in Temescal Canyon (Figure 1). North of Temescal Canyon, the creek flows into lined channels of the City of Corona’s stormwater system and receives stormwater runoff from most of the Temescal Subbasin.
Surface water inflows into Bedford Subbasin along Temescal Wash are the result of runoff from surrounding areas. South of Bedford Subbasin, flows along the creek are diverted and bermed to create a small area of impounded surface water, locally known as Corona Lake (Figure 1). Historically, releases from this lake supplemented other agricultural water supplies. Currently, EVMWD provides non-potable supply to Coldwater and Bedford subbasins through releases from this impoundment, contributing to surface water inflows during summer months.
Historically, overflow from Lake Elsinore (located about six miles south of Bedford Subbasin) provided surface water to the creek. However, increased water use in the vicinity halted surface water outflow from the lake in the early 1900s (DWR, 1959; MWH, 2003). With the exception of some upstream releases of recycled water to Temescal Creek there are no significant surface or subsurface inflows to the Bedford Subbasin from the Elsinore Subbasin to the south (MWH, 2003) (Figure 1).
2.2. Geology and Faulting
The Study Area is located within one of the structural blocks of the Peninsular Ranges of Southern California. The groundwater basins in this area occur in a linear low-lying block, referred to as the Elsinore-Temecula trough, between the Santa Ana Mountains on the west and the Perris Plain on the east (Norris and Webb, 1990). The trough extends from Corona to the southeast some 30 miles and was formed along an extensive northwest-southeast trending fault zone including the Elsinore, Chino, and related faults. The Elsinore and Chino fault zones bound the subbasins on the west and trend along the mountain front. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
2.2.1. Geologic Units
Figure 4 presents a detailed geologic map illustrating the large number of units in the subbasin as mapped by USGS (2004). The oldest rocks in the Study Area crop out along the eastern edge or the Bedford subbasin. These uplands are composed principally of Mesozoic-age metasedimentary and volcanic rocks including the Estelle Mountain Volcanics (Mzu and Kvem, respectively, on Figure 4). There are also outcrops of Mesozoic metamorphic rocks including the Bedford Canyon Formation to the west of the subbasins in the Santa Ana Mountains (Jbc on Figure 4). Younger sedimentary units of Tertiary age crop out along the mountain front and in the subbasins. In northern Bedford Subbasin, a variety of Tertiary sedimentary units crop out including the Paleocene Silverado (Tsi), Miocene Vaqueros (Tvs), and Miocene Topanga (Tt) formations (Figure 4). Erosion of these units has filled in the trough over time resulting in quaternary-age alluvial fan, channel, and other alluvial deposits, making up the permeable portions of the Bedford and Coldwater groundwater subbasins.
The main surficial deposits on the floor of Bedford Subbasin include younger and older alluvial fans (Qvofg, Qofg, and Qy on Figure 4) deposited from the erosion of Bedford Canyon Formation and granitic rocks to the west. These units prograde across the basin to the northeast and are truncated by channel deposits along Temescal Wash (Qyag).
For analysis of the District’s recharge project, similar alluvial and bedrock geologic units have been combined on Figure 5 to show the areal extent of relative high and low permeability units. The bedrock units, shown by the gray color, group together all of the consolidated units in the subbasin for a better understanding of low permeability areas to avoid for the recharge project.
Alluvial deposits shown in the various shades of green illustrate the surface area of alluvial fans, valley fill, and channel deposits where more permeable sediments occur.
2.2.2. Depth to Bedrock
Although the geologic map shows alluvial sediments covering most of the surface of the Bedford Subbasin, the frequency of bedrock outcrops and shallow depth of many wells are good indications that sediments are likely very thin in some areas. For this reason a bedrock surface was interpolated for the subbasin. Depths to bedrock were noted from water well driller’s logs obtained from the Department of Water Resources. The locations of these wells were approximately plotted using GIS software. The locations of these wells are shown on Figure 6.
These data were combined with locations of known bedrock outcrops from the 2004 USGS geology map to create an approximate depth to bedrock surface. Figure 7 shows a colored raster and contours of the depth to bedrock surface. The bedrock surface map shows that sediments throughout most of the Bedford Subbasin are between 100 and 200 feet thick. Bedrock outcrops in the northern and south-central potion of the subbasin result in relatively thin and discontinuous pockets of alluvial sediments. However, there is an area in the western central portion of the subbasin where alluvial thickness is between 300 and 400 feet. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
2.3. Subbasin Aquifers
The primary aquifer within the Bedford Subbasin is unconfined consisting of alluvial fan gravels prograding across valley fill sediments and interfingering with channel deposits associated with Temescal Wash. Although the alluvial aquifer is composed of material from multiple depositional environments, it is considered to be one continuous aquifer due to its high permeability and the prograding / interfingering nature of the deposits.
The bedrock in the subbasin does have some limited aquifer capacity, and there are some domestic wells that are completed in these bedrock aquifers. Bedrock aquifers in the area are primarily recharged from the alluvial aquifers. For the purpose of this study, the bedrock aquifers were not considered to be targets for recycled water recharge due to their limited capacity to store and transmit water.
2.3.1. Aquifer Geometry
The Bedford Subbasin alluvial aquifer is controlled by surface topography and the underlying erosional bedrock surface. The resulting aquifer is an elongated northwest southeast structure that is deepest in the middle, shallows to the north and east, is bounded by faults on the west, and is dotted by areas of no thickness where bedrock crops out. The aquifer generally slopes down to the northwest where it thins dramatically and is virtually nonexistent at the northern end of the subbasin.
The approximate latitudinal geometry of the alluvial fan deposits in the Coldwater and Bedford subbasins are shown on Figure 8. The cross section shows generalized subbasin geometry from west to east across the Coldwater/Bedford subbasin boundary at the North Glen Ivy fault. Rather than representative of a specific location, the cross section is a schematic profile illustrating the nature and maximum thickness of the alluvial fan aquifers and the relationship with the Temescal Wash deposits. Alluvial sediments are more than 800 feet thick in the Coldwater Subbasin and up to 500 feet thick in the Bedford Subbasin, with the thickest section occurring near the subbasin boundary and fault zone (Figure 8).
Water levels are lower in the western Coldwater Subbasin as a result of pumping by the City of Corona and others in the subbasin (Figure 8). The discontinuity indicated by water levels across the Glen Ivy fault reflects the commonly held view that groundwater is impeded by low permeability clay along the fault zone. This discontinuity has been observed in water levels on opposite sides of the fault by others (MWH, 2004)These and other data indicate that outflow from the Coldwater Subbasin into the Bedford Subbasin only occurs during times of high water levels (MWH, 2004).
2.3.2. Aquifer Parameters
Aquifer parameters for the alluvial aquifer in the Bedford Subbasin are not available throughout most of the subbasin. However, a 72-hour constant rate pumping test was performed )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
on a District well, Well 1A, in February 2003 by Foothill Engine & Pump Company.
Groundwater levels in Well 1A, and nearby Wells 3 and 4, were monitored during the test and recorded on field forms by the pumping contractor. The locations of the District wells are shown on Figure 6. No aquifer parameter analysis appears to have been conducted for these data.
Therefore, data from this test were made available for analysis by the District as part of this project. Test data from the three wells were plotted on a semi-log graph of drawdown versus time.
The graph of these data and the resulting straight line portions are shown on Figure 9. Straight line portions of the data were identified on this graph in order to apply the Cooper-Jacobs straight line approximation for the calculation of transmissivity (T) and storage coefficient (S) as shown by the following equations:
ܶ ൌ ଶସொ
ο௦
and ܵ ൌ Ǥଷ்௧బ
మ
Where T = transmissivity
S = storage coefficient
Q = pumping rate
¨s = drawdown for one log cycle
t0 = time when drawdown equals zero
r = radius of observation point from pumping well
Data from Well 3 appeared to be the most representative of stabilized aquifer conditions and were less affected by the sporadic breaks in drawdown that were present in the data from Well 1A. Using these data, the calculated aquifer transmissivity is 144,000 gallons per day per foot (gpd/ft), equivalent to 19,250 square feet per day (ft2 /day). Storage coefficients were
calculated for the straight lines from Wells 3 and 4 at 0.10 and 0.15, respectively. These values represent an effective porosity of the alluvial aquifer of 10 percent from Well 3 and 15 percent from Well 4. Well logs for District Wells 1A, 3, and 4 were not available for this analysis.
However, nearby domestic well logs indicate a total saturated aquifer thickness of about 77 feet.
Using this value for the saturated aquifer thickness (b), a hydraulic conductivity (K) of 250 feet per day (ft/day) was calculated for the aquifer using ܭ ൌ ܶȀܾ. Because this represents the only K value available in the basin, it is unknown whether the data are representative. As such, a slightly lower K value of 200 ft/day is used for further analysis of the alluvial aquifer.
2.4. Groundwater Use and Wells
Groundwater has been used as an irrigation water supply in the Bedford Subbasin for at least 80 years. Published data on wells in the Temescal Valley indicate that at least eleven wells had been drilled for irrigation supply in the Bedford Subbasin (or just downgradient of the boundary) by 1957 (DWR, 1959). One shallow well was reported to have been in place since )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
1912. Driller reports obtained from DWR indicate that more than 100 wells have been drilled in the subbasin.
2.4.1. Subbasin Production
Groundwater pumping data are available from a private firm, Watermaster Support Services (WMSS), which compiles well and pumping data for the Temescal Valley subbasins and other basins in the Santa Ana River watershed. Data from 1947 through 2006 were obtained from WMSS and reviewed for this project. During this period, approximately 22 wells have extracted groundwater in the subbasin. These data include three irrigation wells that pump just outside of the subbasin at the mouth of Bedford Canyon (referred to as the EVWMD Flagler wells).
Production from the Flagler wells is included in this analysis because they pump immediately downgradient of the subbasin and extract groundwater, in part, migrating out of the subbasin.
Annual groundwater production is shown on the top graph on Figure 10. As shown on the graph, Bedford Subbasin production has generally decreased over the last 60 years. From 1947 through 1965, annual production averaged 2,900 AFY. Groundwater pumping increased from 1966 through 1971, averaging about 4,000 AFY with a peak in 1966 of 4,658 AFY. Through the 1970s and into the early 1990s, average production declined to about 2,500 AFY. Since 2000, production has declined to about 1,000 AFY and averaged only 245 AFY in 2005-2006.
Several water companies were formed in the subbasin before 1950 to provide irrigation water for subbasin agriculture (DWR, 1959). These companies secured surface and groundwater supplies and operated several groundwater wells in the subbasin. When the District was formed in 1965, two existing production wells were acquired to supplement the District’s imported water supply. Production from these two wells by the District and previous well owners are summarized on the graph on the bottom of Figure 10. As shown on the graph, production from the District wells has also declined over time. From 1947 through 1970, production averaged about 676 AFY, accounting for about 20 percent of the documented subbasin pumping. From 1972 through 1995, average production declined by more than one half to 274 AFY (about 10 percent of subbasin production). Over the last 10 years, production has declined to less than 20 AFY and the wells are not currently used for potable water supply.
2.4.2. Domestic Wells
Although there is very little documented domestic groundwater extraction from the subbasin, private wells used for domestic water supply likely exist in the basin. DWR driller’s logs indicate that some wells were previously permitted for domestic supply as well as irrigation.
The number of active wells is not known. The drilling of domestic wells (and other wells) requires a permit to be filed with Riverside County Division of Environmental Health (DEH).
The County maintains these well permits in their records and compiles information into a database as internal resources allow. Communication with the County revealed that their databases does not currently allow for geographic filtering of well information and therefore )HDVLELOLW\6WXG\//:'
7RGG(QJLQHHUV
accessing the data for Bedford Subbasin wells would require considerable effort on the part of County staff. Unfortunately, due to current staffing levels, the County cannot accommodate this type of search in a timely manner. As such, permit data were not reviewed for this project.
2.5. Groundwater Occurrence and Flow
Groundwater occurrence in the unconfined aquifer of the Bedford Subbasin is controlled by recharge and outflow. The primary source of recharge to the alluvial aquifer is runoff from the watershed to the east and percolation of precipitation. Additional runoff enters the basin and the aquifer from the west, but this must first travel through the Coldwater Subbasin, where most of the water infiltrates. Some additional recharge also occurs as a result of subsurface inflow from the alluvial aquifer in the Coldwater Subbasin. However, this recharge source is limited by groundwater pumping in Coldwater Subbasin and impedance across the Glen Ivy fault. Very little, if any, groundwater enters the subbasin from Lake Elsinore due to its limited releases.
Groundwater flow in the subbasin is generally easterly toward Temescal Wash and then northwesterly following surface water drainage.
2.5.1. Water Levels and Depth to Water
Very few wells in the Bedford Subbasin provide a sufficient water level record to analyze long term trends. However, there are scattered wells throughout the subbasin with original static water levels from water well driller’s logs. These water levels were recorded at the time of installation of the wells shown on Figure 6. Since these wells have been constructed over a period of approximately 50 years spanning various hydrologic conditions, it can be reasonably assumed that they collectively approximate average static water levels. Contours of the depth to groundwater, as shown on Figure 11, were created using these data. In addition, there are a number of wells near the northeast outflow of the subbasin that allow for an analysis of water levels at that location (Figure 6). As shown on Figure 11, groundwater is deepest in the western portion of the subbasin (up to about 100 feet deep). Shallower groundwater occurs in the eastern subbasin near Temescal Wash. The exact groundwater-surface water interaction along the wash has not been documented, but groundwater likely provides baseflow to the creek in shallow bedrock areas and the creek likely recharges groundwater where water levels are deeper. As Temescal Wash exits the subbasin in the northeast, groundwater discharge likely occurs.
One former well, operated by the City of Corona (Well 4), is located about 950 feet north of the northeast corner of Bedford Subbasin at the mouth of Bedford Canyon. Wells pumping in this area receive recharge from runoff in adjacent Bedford Canyon (Temescal Subbasin) as well as surface and subsurface outflow from Bedford Subbasin (Figure 1). As such, water levels in this area are indicative of the total groundwater and surface water discharge where Temescal Wash temporarily leaves the subbasins. A hydrograph from this Bedford Canyon well is shown below. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
Groundwater Elevation, feet msl
Date
City of Corona Well No. 4
Bedford Subbasin Northern Boundary 1964 - 2004
The ground surface elevation at this well is reported to be about 791 feet msl indicating that water levels are within 10 feet of the ground surface during times of high water levels. This is to be expected given the downgradient location of the well and its position near rising groundwater that enters Temescal Canyon as surface water in the wash. Downstream ground surface elevations are around 780 feet, similar to water levels in the well. It appears that this elevation is acting similar to a drain, and likely indicates the level at which the groundwater basin is discharging to Temescal Wash. Given the shallow groundwater, this location would not be applicable to a District recharge project; nonetheless the hydrograph provides a record for longterm water levels at the downgradient extent of the subbasin.
As shown on the hydrograph, water levels have fluctuated only about 60 feet over the last 40 years. Water levels have been recorded as high as 782 feet, but have remained above about 770 feet for most of the period of record. Water levels dropped to around 720 feet during the relatively dry cycle from 1987 to 1995. According to a DWR study (1980), groundwater levels in the Bedford Subbasin fluctuate considerably during the year as a result of seasonal pumping and considerable recovery of water levels during the rainy season. This observation indicates that infiltration of recycled water at the surface can readily recharge the alluvial aquifers.
2.5.2. Groundwater Flow
Most of the subsurface flow in the Bedford Subbasin parallels surface water flow to the northwest along Temescal Wash. However, flow is easterly in the western portion of the subbasin, generally following surface topography. In the northern portion of the subbasin, groundwater )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
flow becomes more complex as a result of refraction around low permeability bedrock.
Throughout the subbasin, groundwater flow is generally controlled by surface topography.
2.5.3. Groundwater Quality
Groundwater quality data for the Bedford Subbasin alluvial aquifer at this time are limited to samples collected from District Well 1A in February 2003 and in Well 4 in August 2007. A complete list of analytical parameters and the concentrations at which they were detected is presented in the following table.
Table 2-2
Groundwater Quality Data
District Wells 1A & 4
Well :HOO$ :HOO
Sample Date
pH PJ/
Calcium PJ/
Magnesium PJ/
Nitrate
as N PJ/
Nitrite
as N PJ/
Ammonia PJ/
Sulfide PJ/
Total
Hardness PJ/
Total
Dissolved
Solids
PJ/
Total
Suspended
Solids
PJ/
Chlorine
Residual PJ/
Oil &
Grease PJ/
As shown by the values for total dissolved solids (TDS), groundwater contains a relatively high mineral content in the subbasin. The TDS value of 690 mg/L exceeds the secondary maximum contaminant level (MCL) of 500 mg/L. This MCL is not based on health )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
risk, but rather aesthetic values such as odor or taste. The value of total hardness of 370 mg/L indicates a water classified as very hard (Todd and Mays, 2005), which can result in scale deposition in pipes and other inconveniences. Preliminary review of these data indicates that recycled water may be of higher quality for some constituents than ambient groundwater.
Recycled water quality data are reviewed in the following section. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
3. Considerations for Groundwater Recharge
The District’s recharge project was evaluated in the context of the hydrogeologic setting of the subbasin and District objectives. Based on this analysis, potential recharge locations and methods were selected. This section describes the evaluation and provides project parameters, methods of analysis, assumptions, regulatory considerations, and results.
3.1. Recharge Water Parameters
Based on communication with the District and a review of current permit requirements and data, the following parameters and data have been incorporated into the analysis.
3.1.1. Quantity Available for Recharge
In compliance with the current NPDES permit, the District can discharge up to 1,570,000 gpd of recycled water to Temescal Creek. The District is currently discharging about 700,000 gpd during non-irrigation months. The recycled water demand is much larger in summer months and discharge to the creek is significantly reduced during that time. The WRF is capable of reclaiming up to about 1,570,000 gpd, but demand for recycled water is also expected to rise (LLWD, 2008).
For the purposes of this preliminary analysis, we assume that a current continuous flow of 700,000 gpd is available for recharge on a six-month basis. This amount is equivalent to a continuous recharge rate of 486 gpm. The recharge method and location selected for the District’s project needs to accommodate this rate and amount. Additional recycled water will likely be available in the future although the exact amount is unknown. Even though the analysis is based on 700,000 gpd, the potential for increasing this amount is also considered.
3.1.2. Recycled Water Quality
The WRF produces tertiary-treated wastewater derived from imported SWP water. This water source is considered to be higher quality than local groundwater for many parameters.
According to a 2006 report to consumers, the imported water contains an average TDS of 200 mg/L (LLWD, 2006) compared to a groundwater supply of about 690 mg/L. Although mineral content is concentrated in the wastewater, elevating the TDS, the recycled water is expected to be equal to or better than ambient groundwater quality.
Water quality data from the WRF are available in connection with the District’s monitoring program. These data were provided by the District and reviewed for application to the recharge project. Table 3-1 presents a summary of recycled water data with a focus on the parameters relevant to recycled water recharge regulations (Section 60320.030 in DPH, 2007).
The table is presented on the following pages and described in the text following the table. )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
Recycled Water Analytical Results Average Concentrations 2002 - 2007
ANALYTE
Italics - UHTXLUHGIRUUHFKDUJHSURMHFWE\'3+
Average Result
bold underlineH[FHHGV0&/
RU6HFRQGDU\0&/
Number of
Detections
Number of
Non-Detect
Results (ND)
Maximum
Contaminant
Level
(MCL)
Secondary MCL Units
Aluminum 1RW$QDO\]HG PJ/
Antimony 1' PJ/
Arsenic PJ/
Asbestos 1RW$QDO\]HG 0)/
Barium 1' PJ/
Beryllium 1' PJ/Cadmium 1' PJ/
&DOFLXP
PJ/
Chloride
PJ/
Chromium (Total) 1' PJ/
Chromium (Hexavalent) 1' PJ/
Copper PJ/
Cyanide 1' PJ/
Fluoride 1RW$QDO\]HG PJ/
Iron
PJ/
Lead 1' PJ/
Magnesium PJ/
Manganese
PJ/
Mercury 1' PJ/
Table 3-1
Nickel 1' PJ/
Nitrate as N
PJ/
Nitrite as N
PJ/
Nitrogen (as Ammonia) PJ/
Total Nitrogen (ammonia, nitrate, & nitrite)
&DOFXODWLRQ &DOFXODWLRQ
PJ/
,QRUJDQLF1LWURJHQ PJ/
%LRFKHPLFDO2[\JHQ'HPDQG
PJ/
Perchlorate 1RW$QDO\]HG PJ/
Selenium PJ/
Silver 1' PJ/
Sodium PJ/
Sulfate
PJ/
Thallium 1' PJ/
Bicarbonate 1RW$QDO\]HG PJ/
Carbonate 1RW$QDO\]HG PJ/
Alkalinity 1RW$QDO\]HG PJ/
Total Hardness PJ/
Zinc PJ/
pH
6WDQGDUG8QLWV
Foaming Agents (MBAS) 1RW$QDO\]HG PJ/
Turbidity 1RW$QDO\]HG 178
Total Dissolved Solids 554
PJ/
7RWDO6XVSHQGHG6ROLGV PJ/
7RWDO&ROLIRUP 031P/
Total Organic Carbon 1RW$QDO\]HG
PJ/
/HH/DNH:DWHU'LVWULFW5HFKDUJH)HDVLELOLW\7
?3URMHFWV?/HHB/DNHB5HFKDUJHB?'DWD?:DWHUB4XDOLW\?//:'5:(II&RPSDULVRQ[OV[ 7RGG(QJLQHHUV
Recycled Water Analytical Results Average Concentrations 2002 - 2007
ANALYTE
Italics - UHTXLUHGIRUUHFKDUJHSURMHFWE\'3+
Average Result
bold underlineH[FHHGV0&/
RU6HFRQGDU\0&/
Number of
Detections
Number of
Non-Detect
Results (ND)
Maximum
Contaminant
Level
(MCL)
Secondary MCL Units
Table 3-1
Radium-226 1RW$QDO\]HG S&L/Radium-228 1RW$QDO\]HG S&L/ Gross Alpha 1RW$QDO\]HG S&L/
Uranium 1RW$QDO\]HG S&L/
Beta / photon emitters 1RW$QDO\]HG PLOOLUHP\HDU Strontium-90 1RW$QDO\]HG S&L/
Tritium 1RW$QDO\]HG S&L/ 1,1,1-Trichloroethane 1' PJ/
1,1,2,2-Tetrachloroethane 1' PJ/
1,1,2-Trichloro-1,2,2-Trifluoroethane 1RW$QDO\]HG PJ/ 1,1,2-Trichloroethane 1' PJ/
1,1-Dichloroethane 1' PJ/
1,1-Dichloroethylene 1' PJ/
1,2,4-Trichlorobenzene 1' PJ/
1,2-Dichlorobenzene 1' PJ/
1,2-Dichloroethane 1' PJ/
1,2-Dichloropropane 1' PJ/
1,3-Dichloropropene 1RW$QDO\]HG PJ/
cis-1,3-Dichloropropene 1' PJ/
FRPELQHG
cis 1,3 Dichloropropene 1' PJ/
trans-1,3-Dichloropropene 1' PJ/
1,4-Dichlorobenzene 1' PJ/
2,3,7,8-TCDD 1RW$QDO\]HG PJ/
2,4,5-TP 1RW$QDO\]HG PJ/
2,4-D 1RW$QDO\]HG PJ/
Alachlor 1RW$QDO\]HG PJ/
Atrazine 1RW$QDO\]HG PJ/
Bentazon 1RW$QDO\]HG PJ/
Benzene 1' PJ/
Benzo(a)pyrene 1' PJ/
Bromodichloromethane PJ/
Carbofuran 1RW$QDO\]HG PJ/
Carbon Tetrachloride 1' PJ/
Chlordane 1' PJ/
Chloroform
PJ/
cis-1,2-Dichloroethylene 1RW$QDO\]HG PJ/
Dalapon 1RW$QDO\]HG PJ/
Di(2-ethylhexyl)adipate 1RW$QDO\]HG PJ/
Di(2-ethylhexyl)phthalate 1' PJ/
Dibromochloropropane 1RW$QDO\]HG PJ/
Dichloromethane 1' PJ/
Dinoseb 1RW$QDO\]HG PJ/
Diquat 1RW$QDO\]HG PJ/
Endothal 1RW$QDO\]HG PJ/
Endrin 1' PJ/
Ethylbenzene 1' PJ/
Ethylene Dibromide 1RW$QDO\]HG PJ/
Glyphosate 1RW$QDO\]HG PJ/
Heptachlor 1' PJ/
Heptachlor Epoxide 1' PJ/
Hexachlorobenzene 1' PJ/
Hexachlorocylopentadiene 1' PJ/
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Recycled Water Analytical Results Average Concentrations 2002 - 2007
ANALYTE
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Average Result
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Number of
Detections
Number of
Non-Detect
Results (ND)
Maximum
Contaminant
Level
(MCL)
Secondary MCL Units
Table 3-1
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Methoxychlor 1' PJ/
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Styrene 1RW$QDO\]HG PJ/
Tetrachloroethylene 1' PJ/
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trans-1,2-Dichloroethylene 1' PJ/
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Table 3-1 presents concentrations of metals and other inorganic constituents and physical parameters in the first grouping of analytes. These data are followed by radionuclides that are required for monitoring of recycled water recharge. The last group of analytes contains organic chemicals. Also included on the table are primary and secondary maximum contaminant levels (MCLs) pertinent to regulations for recharge of recycled water (DPH, 2007). Concentrations listed in the column of Average Result are average concentrations of detections from 2002 through 2007 and do not consider samples when the concentration was not detected above reporting detection limits (Table 3-1).
As shown on Table 3-1, the District’s recycled water appears to meet regulatory requirements for constituents analyzed to date. The average TDS is about 555 mg/L, slightly larger than the secondary MCL of 500 mg/L. However, this is lower than the TDS concentration detected in the limited groundwater data presented above. As noted at the bottom of the table, TDS concentrations above 500 mg/L may be recharged and short-term concentrations of up to 1,500 mg/L may be allowed.
Regulations require control of total nitrogen compounds in recharge water. Total nitrogen as defined by the regulations is the sum of nitrogen in ammonia, nitrite, nitrate and other organic nitrogen-containing compounds. Total nitrogen is calculated on Table 3-1 and averages 8.8 mg/L.
Total nitrogen may be limited to as low as 5 mg/L for a recharge project. If the 5 mg/L objective is exceeded, additional groundwater monitoring and/ or blending will likely be required to demonstrate that groundwater quality has not been adversely impacted. Regulations allow for alternative concentration limits to be proposed for a recycled water recharge permit (DPH, 2007).
Nitrate, one of the nitrogen compounds of particular concern, meets primary standards as shown on Table 3-1. Concentrations of nitrate (as N) in recycled water average 3.4 mg/L from more than 261 samples analyzed. This value is well below the MCL of 10 mg/L.
Radionuclide data are currently unavailable for the WRF water. The seven parameters listed on Table 3-1 summarize the regulated analytes.
Organic chemicals regulated for recycled water recharge are listed on Table 3-1 beginning on the second page of the table. Almost all of these chemical have been analyzed in recycled water in at least one sampling event since 2002. Most of the data were developed during two sampling events in 2005 (winter and summer) and one event in January 2007. For those sampling events, there have been no detections of any organic chemical that did not meet water quality standards for regulated compounds. Two organic chemicals detected are classified as trihalomethanes (THMs), a group of chemicals formed when chlorine is used to control microbial contaminants in water (referred to collectively as disinfection byproducts). Analyses of THMs include chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Of these chemicals, chloroform and bromodichloromethane have been detected in recycled water samples.
Chloroform has been detected in three samples at 0.0026 mg/L, 0.008 mg/L, and 0.015 mg/L. All detections meet water quality standards and were significantly lower than the MCL of 0.080 )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
mg/L. Bromodichloromethane has also been detected in three samples at concentrations of 0.009 mg/L, 0.002 mg/L, and 0.0063 mg/L, all at least one order of magnitude below the MCL of 0.080 mg/L. Only one other organic contaminant, toluene, has been detected in effluent samples. The concentration of that detection (0.007 mg/L) was about two orders of magnitude lower than the MCL of 0.15 mg/L.
As shown on the table, radionuclides and several inorganic and organic constituents have not yet been analyzed in District recycled water because they are not required for current monitoring. The table contains a more complete list of constituents to allow the District to review additional constituents to be analyzed for the recharge project if implemented. In addition to the constituents and parameters provided on Table 3-1, total organic carbon must meet stringent regulatory requirements. DPH will also require initial testing and monitoring for specific nonregulated compounds.
3.2. Hydrogeologic Considerations
Hydrogeologic conditions within the groundwater subbasin are important to the performance of a successful recharge project. The vadose zone above the water table must be sufficiently permeable to percolate the recharge water and there must be sufficient storage to accommodate the water during the recharge period. Aquifers must be sufficiently permeable to transmit the recharge water downgradient toward the basin discharge point or extraction wells.
During an evaluation of recharge sites in the Lucerne Valley, USGS developed a general list of criteria for site selection. Although the list is specific to large spreading basins, the criteria are applicable to many recharge sites and methods. These criteria are listed below:
1. The infiltration rate of the spreading grounds must be high enough to accept the anticipated rate of recharge.
2. The storage capacity of the groundwater basin must be adequate to accommodate the anticipated volume of recharge.
3. The transmissivity of the water-bearing material must be sufficient to transmit the water at an acceptable rate away from the recharge site toward the area of extraction.
4. An adequate supply of water must be available for recharge, and it must be close enough to the area of need to meet economic criteria.
5. The spreading grounds should be upgradient of the withdrawal areas or be so situated with respect to withdrawal areas that water moves as directly as possible from one area to the other.
6. Faults and other hydrogeologic barriers should not impede the movement of recharge water.
7. The recharge water should be compared geochemically with ambient groundwater to minimize mineral precipitation and clogging of the aquifer with consequent reduction in rates of recharge.
For application to the District’s recharge project, criteria 1-3 above are considered the most critical for project success. Data relevant to the infiltration potential, storage capacity, and transmissivity were discussed in the hydrogeologic setting. Although site-specific tests have not )HDVLELOLW\6WXG\//:'
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yet been conducted to determine infiltration rates, surface alluvial sediments are judged generally adequate for sufficient infiltration. Soil mapping conducted by the U.S. Natural Resources Conservation Service (NRCS) indicates permeable soils over the entire subbasin except in areas where bedrock crops out (NRCS, 2006). The transmissivity of the aquifers, as indicated by the aquifer test at District Well 1A, indicates sufficient permeability for downgradient transport of recharge water away from the recharge site and toward extraction wells. The exact storage capacity of the groundwater basin is currently unknown. Most of the storage is in the alluvial sediments that have infilled the basin around areas of shallow bedrock. The surface area of the subbasin is approximately 4,133 acres, but includes areas of bedrock and negligible groundwater storage. Using reasonable assumptions of two-thirds of the surface area (2,769 acres), an average depth to water of 50 feet, and an S value of 0.15, available subbasin storage is estimated to be about 20,000 AF. Storage estimates are judged adequate for the relatively small volume of recharge considered for this project, approximately 400 AFY of current discharge and 900 AFY at full permitted plant capacity assuming six months of continuous recharge. In addition, both the District and others have indicated an interest in additional extraction in the subbasin, making enhanced recharge a critical component of groundwater management.
Criterion 4 addresses the availability of source water for the project. WRF capacity and water quality data indicate that a reasonable amount of recycled water of sufficient quality is available. In addition, the current and planned conveyance system for recycled water anticipates increased demand throughout most of the subbasin. As such, sites within the central and northern Bedford Subbasin are considered sufficiently close to the recycled water conveyance system for the purposes of this feasibility study. If the project moves forward, final site selection will consider distance to conveyance and costs.
With regard to criterion 5, the upgradient (southern) portion of the subbasin was considered to be higher priority and was targeted for site selection. This criterion was balanced with the need for more favorable aquifer conditions than exist in the most upgradient portion of the subbasin where bedrock crops out, aquifers are thin, and the water table is shallow.
Criterion 6 notes the need to understand subbasin hydrogeology and potential barriers to groundwater flow. Geologic faults, such as the Glen Ivy fault on the western subbasin boundary, have been observed to impede groundwater flow in the area. Additional faults impacting groundwater flow have not been identified within the central and northeastern portions of the Bedford Subbasin. As such, specific faults are not considered to limit project site selection.
Bedrock outcrops of the Bedford Subbasin are also considered to be hydrogeologic barriers, where low permeability rock impedes and diverts groundwater flow. Recent mapping in the area by USGS provided guidance on more favorable areas based on surface geology. For this project, Todd Engineers also constructed a detailed map on the depth to bedrock across the subbasin based on existing data (Figure 7). This map was used to identify more favorable areas away from shallow bedrock.
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The final criterion in the previous list, criterion 7, addresses the compatibility of the recharge water and ambient groundwater to ensure long-term infiltration can be sustained without well or aquifer damage. This compatibility issue is typically evaluated using geochemical models, such as the USGS-developed model PHREEQC (Parkhurst and Appelo, 1999). Data are currently insufficient to conduct geochemical modeling. Site-specific data will need to be collected for this evaluation after a project site is selected.
3.2.1. Potential Recharge Methods
To replenish the unconfined alluvial aquifer, recycled water can be applied in one of several ways: at the surface using infiltration basins, directly into the aquifer using injection wells, or into the subsurface above the water table using vadose zone wells. Each of these recharge methods are illustrated by the schematic diagram on Figure 12. For surface basins, water infiltrates the basin floor and percolates through the vadose zone to the underlying water table (Figure 12). If clay layers are present in the vadose zone, or if sufficient land for recharge basins is unavailable, vadose zone wells can provide a space-efficient pathway for project water to reach the water table. If clay layers are prevalent, especially if they represent confining layers in the aquifer system, injection wells can be used to access aquifers more directly for recharge. Either of these methods, or a combination of methods, could potentially be applied to the District’s recharge project. The applicability of each method to the District’s project is discussed below.
3.2.1.1. Surface Basins
The use of surface recharge basins involves conveyance of recycled water to a shallow excavated basin or series of basins where water would pond and infiltrate to underlying groundwater. Recharge basins have been used for conjunctive use and enhanced recharge projects for almost a century in areas of Riverside and San Bernardino counties. Since the alluvial aquifers of the Bedford Subbasin are considered to be unconfined, surface recharge would likely be capable of replenishment of subbasin aquifers. The size of the basin depends on the amount of water to be recharged and infiltration rates.
The infiltration rate varies with vadose zone permeability, depth to water, water quality, and other factors. Infiltration rates tend to decrease over time due to physical and/or biological clogging of the basin floor. Maintenance often involves drying and re-working the shallow subsurface. Physical clogging is anticipated to be less with recycled water, given the low amount of suspended solids. To maximize infiltration rates, relatively shallow basins are preferred (Bouwer, 2002).
Using a typical infiltration rate of about two feet per day (ft/day), a one-acre area is calculated to be capable of recharging about 450 gpm, a rate similar to that required for the District project. However, to allow for basin edge effects, maintenance, and other project needs, a minimum area of two acres should be considered.
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Surface recharge basins provide the following project benefits:
x Relatively simple to construct and maintain
x Ability to spread recharge water over a large area, minimizing water levels impacts
x Water quality benefits by filtration through the vadose zone x Ability to rehabilitate shallow clogging problems
Several disadvantages are associated with surface recharge basins compared to other recharge methods including:
x Larger land requirements
x Relatively large environmental footprint
x Potential security and liability issues
3.2.1.2. Vadose Zone Wells
If sufficient land is unavailable for the construction of relatively large surface basins, vadose zone wells can be used. These wells, also referred to as dry wells, consist of an engineered casing/screen/gravel pack assembly installed in a shallow boring above the water table. Vadose zone wells can also be used to by-pass shallow clay layers that may impede or divert percolating recharge water (Figure 12). The amount of clay in the vadose zone throughout the Bedford Subbasin is unknown, but is predicted to be relatively low. Thus, this may not be an important advantage for the District’s project. Nonetheless, wells are relatively inexpensive to construct and use, especially for the amounts of water to be recharged in this project. Vadose zone wells can be constructed in a developed area and need relatively small areas for installation and operation. In addition, they can be constructed on several separate parcels, if needed, allowing for a series of smaller projects rather than one larger recharge project. If infiltration rates are relatively high, only a few vadose zone wells would likely be needed to accommodate the District’s project.
One major disadvantage is the inability to rehabilitate wells should they become clogged or ineffective. The entrainment of air is often cited for problems with decreasing infiltration rates.
However, it is relatively easy to abandon and replace wells as needed.
3.2.1.3. Injection Wells
For more direct recharge into the aquifer, injection wells can be used. These wells are constructed similar to production wells, but are configured for injection. Wells are effective in areas of relatively shallow water tables or for confined aquifers. Because well clogging typically decreases injection rates over time, wells need to be pumped periodically for maintenance, a process referred to as backflushing. The frequency of required backflushing varies from project to project, but is assumed to be required on a bi-weekly or monthly basis. Pumping for )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
backflushing is typically conducted at twice the injection rate. As such, a dedicated pump is usually installed in the injection well with a flow control valve that allows for both injection and pumping to occur in the same wellbore.
Injection wells cost more to install than vadose zone wells and are often associated with significant maintenance costs. Land requirements are typically smaller than for surface recharge basins, but larger than for vadose zone wells since pumping and backflushing operations must be accommodated. However, they can serve as an effective method of recharge.
3.2.1.4. Recharge Methods for District Project
As discussed above, any of the three methods could be applicable for recycled water recharge in the Bedford Subbasin. For a conceptual cost comparison, a recharge basin may be the less expensive alternative if land costs are not considered. The process of constructing a shallow basin is relatively straightforward and fewer inaccessible project components are developed.
However, because of the larger land requirement, this method could also easily be the most expensive method depending on land costs. Injection wells would be relatively shallow for this project and would not likely be cost prohibitive. However, the clogging issues and backflushing requirements add significantly to project risk. Existing wells would not be good candidates for use as injection wells, given the lack of construction information, well seals, and the desire by the District to pump wells for water supply in the future. Recharge regulations require a minimum distance from drinking water wells. Vadose zone wells are likely the least expensive recharge option when land costs are considered. Since injection capacity is relatively low for vadose zone wells compared to recharge basins, numerous wells are often required to support a recharge project. However, for the small volume of recharge water associated with this project, this alternative seems slightly more favorable. Because all methods appear feasible, none are eliminated for the purposes of this study. Detailed costs can be generated when a specific site and data are available, and a method can be selected at that time.
3.2.2. Selection of Favorable Areas
For the purpose of this feasibility study, three favorable areas were chosen as potential recharge sites. A variety of factors were analyzed in order to select these favorable areas including:
x Depth to bedrock / alluvial thickness
x Depth to groundwater
x Land Use
x Soil / vadose zone lithology and permeability
x Distance to aquifer boundaries
x Ease of obtaining land
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As a result of this analysis, the basin was subdivided into five priority zones, with Priority 1 being the most favorable and Priority 5 the least. The distribution of the zones is presented on Figure 13. The areas indicated as Priority 1 were chosen as the most suitable locations for potential recharge facilities. Areas at and near outcrops of bedrock are rated the lowest priority as shown by the gray areas of the subbasin on Figure 13. The southern segment of the subbasin is rated relatively low (Priority 4), even though alluvial deposits and depth to groundwater may present favorable conditions. This low rating is due to the concern that recharge water would be discharged to Temescal Wash as the creek crosses an area of very thin sediments to the north, removing the project water from the groundwater basin without adding to subbasin yield. Areas designated Priority 3 were judged too close to the creek and areas of shallow groundwater and land use considerations. Priority areas 2 were so-designated based on land use and, to some extent, less certainty in hydrogeology. Priority areas 1 were carried forward for further evaluation.
The District currently produces up to 700,000 gallons per day (gpd) of recycled water for potential recharge, an amount equivalent to 2.15 AF/day. The District is permitted to produce 1,570,000 gpd (4.82 AF/day) of recycled water at full build-out. Assuming a conservative recharge rate of 2 ft/day (only one percent of the measured hydraulic conductivity of the aquifer), a recharge basin with a minimum of 1.07 acre infiltration area (wetted area within a recharge basin) would be sufficient to recharge the current quantity of WFR water. For full build-out, a recharge basin with a minimum of 2.41 acres of infiltration area would be required. These parameters are used to evaluate project impacts to subbasin water levels as described below.
3.2.3. Groundwater Mounding Estimates
Potential recharge basins were plotted in each of the Priority 1 areas as shown on Figure
14. The depth to bedrock and depth to groundwater were interpolated for each of these three locations from the bedrock and groundwater surfaces on Figures 7 and 11. At Site 1 the interpolated depth to bedrock is 165 feet and the depth to groundwater is 40 feet, giving an approximate aquifer thickness of 120 feet. At Sites 2 and 3 the interpolated depth to bedrock is 370 feet and the depth to groundwater is 75 feet, giving an approximate aquifer thickness of 295 feet. The red area shown on the figure at Sites 1 and 3 covers approximately five acres, which is about the size necessary for the berms and other structures associated with a recharge basin with a one- to two-acre infiltration area. The blue area in the center of each of the three basins is just over one acre and represents the potential minimum size of the necessary infiltration area.
For a surface recharge project, water levels rise beneath the recharge area creating a groundwater mound. The height and extent of this mound varies over time with hydraulic properties of the aquifer and the amount of water being recharged. The development of a groundwater mound beneath the Study Area was evaluated using an analytical equation developed by Hantush (1967). The Hantush equation estimates the height of the groundwater )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
recharge mound as a function of time and distance from the recharge area. The Hantush equation assumes that the underlying aquifer is unconfined, homogeneous, isotropic, and effectively infinite in areal extent. The analysis does not account for travel time and lateral flow of recharge water through the unsaturated zone, a sloping groundwater table, aquifer boundaries such as surface water bodies, bedrock, or faults, or aquifer stresses, such as pumping.
The Hantush equation was solved using the mounding function for a circular recharge area in Aqtesolv P ( s: ro 4.0 Hydrosolve, Inc., 2006), the equation for which follow ܼሺݎǡ ݐሻ ൌ݄
ଶ െ݄
ଶ ൌ ሺܸ ʹܭߨ Τ ሻ൫ݓሺݑሻ ൫ͳ െ ݁ሺି௨బሻ
൯Ȁݑ൯
where,
ܼሺݎǡݐሻ = Height of the mound above initial height of water table with respect to ݄ = Height of mound above aquifer base
distance from center of recharge area over time
= Volume of recharge water expressed as wSR2, where w is the vertical infiltration rate from a circular recharge area of radius, R ݄ = Initial height of water table above aquifer base
ܸ
= o tal hydra vity ܭ H rizon ulic conducti of the aquifer ݑሻ Theis well function for nonleaky aquifers
ݑ = ܴଶȀͶ݊ݐR, where ݊ ൌ ܭܾȀܵ݊ and ܾ ൌ ͲǤͷሺ݄ሺͲሻ ݄ሺݐሻ, where ܵ = Storativity, or specific yield of the unsaturated zone, ݐ = time since start of recharge, and ܾ = constant of linearization
ݓሺ =
The decay of the recharge mound can also be estimated in Aqtesolv Pro using the law of superposition: ݄
ଶ െ݄
ଶ ൌ ܼሺݎǡ ݐሻ െܼሺݎǡ ݐ െ ݐሻwhere ݐ is the time elapsed since recharge stops. Recharge mound contours generated by Aqtesolv Pro were exported as shapefiles and projected in the project GIS.
As shown in the Hantush equation, the development of the recharge mound is largely dependent on the vertical infiltration rate (ݓ(, storativity (ܵ) of the unsaturated zone, and the horizontal hydraulic conductivity (ܭு) and thickness of the saturated zone. Based on pumping test data, a ܭு of 200 feet/day, and ܵ of 0.10 and a conservative ܭ of 2 feet/day were applied in the Hantush equation and analyzed for a continuous recharge of six months.
Based on these site-specific input data and the current recycled water production rate of
2.15 AF/day, the calculated maximum height of the recharge mound is estimated to be 2.9 feet at Site 1 and 1.7 feet at Sites 2 and 3 after six months of recharge. At Site 1 the mound dissipates to
0.5 feet high within 4,700 feet of the infiltration basin, while at Sites 2 and 3 the mound is 0.5 feet high at 3,200 feet from the respective infiltration basins. Calculated groundwater recharge mound contours are presented for each of the three sites in Figure 14. The recharge mounds shown on Figure 14 were calculated for recharge basins with approximately 1 acre of infiltration area.
However, these recharge mounds would also be representative for appropriately designed vadose zone wells.
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For the full build-out recycled water production rate of 4.82 AF/day and recharge basins with approximately 2.5 acres of infiltration area, the calculated maximum height of the recharge mound is estimated to be 6.0 feet at Site 1 and 3.3 feet at Sites 2 and 3 after six months of recharge. At Site 1 the mound dissipates to 0.5 feet high within 8,400 feet (1.6 miles) of the basin, while at Sites 2 and 3 the mound is 0.5 feet high at 7,400 feet (1.4 miles) from the infiltration basin.
The Hantush equation method used to estimate groundwater mounding in response to recharge does not account for changes in the geometry of the mound as a result of boundary effects from faults, surface water bodies, or bedrock. However, it appears that the relative size of the mounds at the sites evaluated is small enough that recharge could be accommodated at any of the three locations evaluated above. Further, a larger amount of recycled water could also be accommodated for recharge if additional water is available in the future.
3.3. Regulatory Requirements
The California Department of Public Health (DPH), formerly referred to as the Department of Health Services (DHS), has developed draft regulations for the use of recycled water for groundwater recharge (DPH, 2007). Draft regulations are provided in Title 22, California Code of Regulations, Division 4 Environmental Health, Chapter 3, Recycling Criteria, Articles 1-7, Sections 60301-60323, and endnotes. These regulations provide guidance for siting, operating, and monitoring a recharge project using recycled water. Application of key regulations to the District’s proposed recharge project is summarized below. This discussion is not a comprehensive review of all regulations, but rather identifies preliminary requirements that could impact how the project is implemented.
3.3.1. Distance from Extraction Wells
To ensure the control of potential pathogenic microorganisms, regulations require a specific residence time in the aquifer prior to the extraction of recharged water. Required residence times are six months for a surface recharge project (i.e., spreading basin) and twelve months for a direct injection project (i.e., injection wells). To accomplish this residence time, DPH has considered vadose zone transport and conservative groundwater flow rates to establish a minimum distance between recharge and any drinking water well. Current required distances are 500 feet and 2,000 feet for surface recharge and direct injection, respectively (DPH, 2007). This requirement has been recently reviewed by DPH and will likely be modified to a required distance of 500 feet from a drinking water well for both surface recharge and injection. Although there is no documented current extraction of groundwater for municipal supply in the Bedford Subbasin, there may be active domestic wells with undocumented extractions as indicated by DWR driller’s logs and communications with the District. Riverside County requires well permits for domestic wells and maintains records on those wells. However, due to limited resources, data have not been organized and are not accessible at this time. If the project moves forward, a )HDVLELOLW\6WXG\//:' 7RGG(QJLQHHUV
canvas of active domestic wells will be required within 500 feet and possibly up to 2,000 feet of the selected recharge area.
3.3.2. Diluent Water
As a redundant safety measure for public protection, DPH requires that recycled water recharge projects secure an alternative water source to mix with recycled water for dilution of any undocumented occurrence of constituents of concern. This additional water source, referred to in the regulations as diluent water, must also meet all water quality requirements stipulated for recycled recharge water and must be capable of being monitored to demonstrate water quality.
The mix of diluent water and recycled water varies depending, in part, on the recharge method.
For example, recycled water can account for up to 50 percent of the total recharge water for injection wells but only 20 percent of the total recharge water for surface recharge. This difference reflects the assumed higher level of recycled water treatment for an injection project. If recycled water quality meets regulatory objectives, the same proportion of recycled water can be used for either surface recharge or injection.
The diluent water does not have to be mixed with the recycled water prior to recharge and can be accounted for on a three or five-year average, depending on project operation. Diluent water sources can include stormwater (if collected for recharge and monitored), groundwater, or other surface water source. Recharge of diluent water does not have to be accomplished at the same recharge site, but must be shown to mix with recycled water in the aquifer prior to reaching extraction wells. Diluent water requirements can be reduced or eliminated after a period of monitoring has demonstrated the performance of the project. A meeting with DPH regulators will assist with the determination of diluent water requirements for the District’s recharge project.
3.3.3. Water Quality Requirements
The recharge water must meet numerous numerical and qualitative water quality objectives to be approved for recharge into a groundwater basin that has been designated a source of drinking water supply. At a minimum, the recharge water must be treated to meet the definition of disinfected tertiary recycled water, as defined in Sections 60301.23.
In general, recharge water must meet Title 22 drinking water standards and other requirements for unregulated compounds. Most of the required levels are provided in regulatory tables in Title 22, Chapter 15 including Tables 64431-A (inorganic chemicals), Table 64442/64443 (radionuclides) and Table 64444-A (organic chemicals) (DPH, 2008). Action levels (AL) for lead (0.015 mg/L) and copper (1.3 mg/L) and secondary maximum contaminant levels (MCLs) for certain constituents and characteristics must also be met. Specific requirements for nitrogen compounds vary depending on the location of compliance monitoring. If levels in the recharge water average 5 mg/L with a maximum of 10 mg/L, then concentrations are considered sufficiently low to protect water quality without additional mixing with diluent water or sampling in the vadose zone.
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Recycled water data were provided by the District for a preliminary review of water quality as described previously and presented on Table 3-1. A preliminary review of available data does not indicate non-compliance with recharge regulations. For several constituents, including TDS and total hardness, recycled water quality is better quality than ambient groundwater. For constituents listed on Table 3-1 that have not yet been analyzed, additional laboratory analyses will be required to ensure sufficient water quality for recharge. In addition, regulatory agencies may identify additional water quality constituents that will be considered in a recharge permit, including unregulated compounds.
3.3.4. Monitoring
Compliance monitoring consists of analyses of recharge water, water in the vadose zone or groundwater mound, and/or downgradient groundwater, depending on the constituent being analyzed and the quality of the source water. For example, if certain stringent requirements can be met in the source water prior to recharge, the need to monitor water quality in the vadose zone can be eliminated. In general, upgradient and downgradient monitoring wells will be required to demonstrate the performance of the project.
3.3.5. Other Requirements
There are a number of other requirements that the wastewater management agency (i.e., the District) must meet for a groundwater recharge reuse project including a pollutant source control program, identification of alternative water supplies, a public notification program, and compliance with the details in a project-specific permit. The District should involve early communication with regulators to ensure that the application of regulations to the District’s project is well understood.
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4. Benefits for Groundwater Management
In order to manage the shared groundwater resource of the Bedford Subbasin and provide for planned growth associated with build out, management strategies will be required. The District is cooperating with neighboring agencies including the City of Corona and EVMWD in management of the Bedford Subbasin. Recharge of recycled water appears to be a viable strategy to increase subbasin yield without adverse impacts to groundwater quality.
4.1. Subbasin Yield
In the current draft of the City of Corona’s GWMP, the City plans to increase production immediately downgradient of the Bedford Subbasin. The District also has the option to use additional groundwater for augmentation of water supplies through existing or new Bedford Subbasin wells. The nearby Coldwater and Temescal subbasins have experienced declining water levels. Enhanced recharge through the District’s proposed project could raise groundwater levels and provide additional yield for increased groundwater extraction. As shown on Figure 10, the addition of 400 AFY to basin resources is not insignificant given historical levels of subbasin production. This amount represents about 15 percent of the average groundwater production total in the subbasin over time. If additional recycled water is available in the future, basin pumping above historical levels may be supported.
4.2. Groundwater Quality
Because the source of the recycled water contains significantly less dissolved minerals than ambient groundwater, the quality of the recycled water has the potential to improve local groundwater quality for certain constituents. As previously mentioned, TDS and total hardness are lower in recycled water. Mixing in the aquifer would dilute recycled water with groundwater and potential long-term benefits would require additional analysis. Also, additional water quality analyses are required for a full evaluation of impacts to groundwater quality. Nonetheless, based on existing data, the District’s recharge project is not expected to adversely impact groundwater quality and could improve local quality in some areas.
4.3. Surface Water
Removing the current discharge of recycled water from Temescal Wash will reduce surface water flows in the short term. However, most of the discharge occurs during the wet season when runoff contributes significantly to flows and additional flows are not likely needed to support beneficial uses. By allowing the recycled water to migrate in the subsurface toward surface water discharge at the subbasin boundary, more surface water discharge could potentially be available during dry conditions.
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In addition, several of the constituents in recycled water including selenium have been problematic on occasion for creek discharge. Moving the recycled water to groundwater recharge would eliminate this condition. By allowing the recycled water to receive filtration benefits from aquifer materials, water quality of the recharge water would potentially improve in the subsurface and contribute higher quality water when rising to baseflow at the edge of the subbasin.
The analysis suggests that the basin could accommodate additional recharge from recycled water than amounts analyzed in this memorandum. If more recycled water is recharged than is extracted from production wells, surface water flows would be increased as groundwater rises into Temescal Canyon and exits the subbasin.
These benefits will require further analysis and will be reviewed in the environmental analysis for the City’s GWMP. However, at a minimum, no adverse impacts to surface water are expected.
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5. Conclusions and Recommendations
Based on the Feasibility Study presented in this document, the following conclusions can be made about the District’s proposed recharge project:
x Bedford Subbasin hydrogeology is complicated by complex geology with relatively thin alluvial aquifers interrupted by bedrock outcrops. x Alluvial aquifers are sufficiently thick in some areas to support an enhanced recharge project based on bedrock mapping.
x Aquifer testing in one District well indicates that subbasin aquifers have sufficient permeability and storage to support the District’s project. x Groundwater occurs at depths ranging from 100 feet to about 10 feet across the subbasin and is deepest in the west and shallowest near Temescal Wash. x Groundwater is sufficiently deep in several areas to provide available storage for the District’s recharge project.
x Groundwater quality data are limited, but one analysis indicates very hard water (total hardness of 370 mg/L) with a relatively high mineral content (TDS of 690 mg/L).
x Assuming a conservative infiltration rate of 2 ft/day, WRF recharge would require a minimum infiltration area of 1 acre for the current maximum discharge and 2.5 acres for full build-out.
x An analysis of groundwater mounding indicates that the anticipated water level rise in the vicinity of the proposed recharge sites is estimated to be between 1.7 and 2.9 feet (dependant on the location) for the current maximum WRF output of
2.15 AF/day. It appears that there is adequate unsaturated area in the proposed recharge locations to accommodate this quantity of groundwater. x Further analysis of groundwater mounding for the increased capacity at full build-out (4.82 AF/day) indicates that the water level rise in the vicinity of the proposed recharge sites is estimated to be between 3.3 and 6.0 feet (dependant on the location). It appears that there is adequate unsaturated area in the proposed recharge locations to accommodate this quantity of groundwater. x A comparison of recycled water quality data with regulatory requirements did not identify any significant water quality issues for the District’s project. Additional water quality analyses will be required to demonstrate regulatory compliance if the project is implemented.
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x The District’s project provides management benefits to subbasin yield and, potentially, groundwater and surface water quality.
x Based on the results in this study, the District’s proposed recharge project appears feasible and could involve a variety of recharge methods, depending on final project location.
x The analysis was based on limited data and significant data gaps exist.
Recommendations to address these data gaps are provided below.
For continued assessment and implementation of the District’s project, the following recommendations are provided:
x Include the recycled recharge project in the City of Corona’s GWMP and support GWMP adoption.
x Participate in the environmental review process planned for the City’s GWMP. x Explore options for securing land in the areas designated most favorable for recharge and consider additional infrastructure required for conveyance of recycled water.
x Conduct an exploratory meeting with regulatory agencies regarding project objectives and permit requirements.
x Conduct site-specific evaluations and investigations to determine potential injection rates and aquifer response to recharge.
x Continue and expand recycled water quality testing to include constituents identified on Table 3-1 as well as additional constituents indicated by regulators in preliminary meetings.
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6. References
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Appendices
City of Corona
2025 Urban Water Management Plan
Appendix K – Joint Powers Agreement
JOINT POWERS AGREEMENT
by and among
THE CITY OF CORONA,
a California general law city,
ELSINORE VALLEY MUNICIPAL
WATER DISTRICT,
a municipal water district
and
TEMESCAL VALLEY WATER DISTRICT,
a California water district
for the formation of a joint powers authority and management of
THE BEDFORD-COLDWATER SUB-BASIN
OF THE ELSINORE BASIN
TABLE OF CONTENTS
Page
-i1. RECITALS .......................................................................................................................2
2. DEFINITIONS..................................................................................................................2
3. CERTIFICATION ............................................................................................................3
4. CREATION OF SEPARATE AGENCY .........................................................................3
5. PURPOSES AND MEMBER RESPONSIBILITIES.......................................................4
6. POWERS ..........................................................................................................................4
7. OBLIGATIONS OR LIABILITIES OF AUTHORITY...................................................6
8. DESIGNATION OF ADMINISTERING MEMBER/ADMINISTRATOR....................6
9. ORGANIZATION............................................................................................................6
10. SPECIAL PROJECTS AND PROJECT COMMITTEES................................................8
11. FISCAL AGENT, DEPOSITORY AND ACCOUNTING ..............................................9
12. ACCOUNTABILITY, REPORTS AND AUDITS ..........................................................9
13. OPERATING BUDGET AND EXPENDITURES ..........................................................9
14. CONTRIBUTIONS/BUDGETS.......................................................................................9
15. ASSESSMENTS FOR EXTRAORDINARY COSTS...................................................12
16. STAFFING .....................................................................................................................13
17. DISPUTE RESOLUTION..............................................................................................13
18. WITHDRAWAL.............................................................................................................14
19. TERM AND TERMINATION.......................................................................................15
20. INDEMNIFICATION/CONTRIBUTION .....................................................................15
21. INSURANCE..................................................................................................................16
22. CLAIMS .........................................................................................................................16
23. ENTIRE AGREEMENT REPRESENTED....................................................................16
24. HEADINGS ....................................................................................................................16
Page
-ii25. NOTICES........................................................................................................................16
26. CONSTRUCTION..........................................................................................................17
27. NO THIRD PARTY BENEFICIARIES INTENDED....................................................17
28. WAIVERS ......................................................................................................................17
29. CONFLICT WITH LAWS OR REGULATIONS/SEVERABILITY............................17
30. FURTHER ASSURANCES AND OBLIGATION OF GOOD FAITH
DEALING.......................................................................................................................17
31. COUNTERPARTS .........................................................................................................18
32. AMENDMENT...............................................................................................................18
33. CUA ASSIGNMENT .....................................................................................................18
-1-
JOINT POWERS AGREEMENT BY AND AMONG THE CITY OF CORONA,
ELSINORE VALLEY MUNICIPAL WATER DISTRICT, AND TEMESCAL VALLEY
WATER DISTRICT FOR THE FORMATION OF A JOINT POWERS AUTHORITY
AND MANAGEMENT OF THE BEDFORD-COLDWATER SUB-BASIN OF THE
ELSINORE BASIN
THIS JOINT POWERS AGREEMENT (“Agreement”) is entered into as of ___________________2017, by and between the CITY OF CORONA (“Corona”), a California General Law City organized and existing under the laws of the State of California, ELSINORE VALLEY MUNICIPAL WATER DISTRICT (“EVMWD”), a Municipal Water District organized under Water Code §§ 71000 et seq., and the TEMESCAL VALLEY WATER DISTRICT (“TVWD”), a California Water District organized under California Water Code §§ 34000 et seq., hereinafter collectively referred to as “Members”, with reference to the following:
A. WHEREAS, in September 2014, the Governor signed three bills (SB 1168, SB 1319, and AB 1739) into law creating the Sustainable Groundwater Management Act of 2014 (“SGMA”); and
B. WHEREAS, SGMA generally requires the formation of one or more Groundwater Sustainability Agencies (“GSA” or “GSAs”) responsible for implementing sustainable groundwater management and preventing “undesirable results” in groundwater basins and subbasins designated as a medium or high priority basin by the California Department of Water Resources (“DWR”) in its Bulletin 118 inventory of California groundwater basins; and C. WHEREAS, DWR has designated the Bedford-Coldwater Sub-Basin (the “SubBasin”), as a medium priority groundwater basin under Bulletin 118; and D. WHEREAS, each of the Members overlies a portion of the Sub-Basin and exercises water management, water supply or land use authority within a portion of the Sub-Basin; and E. WHEREAS, the Members are local agencies that can exercise powers related to groundwater management within their jurisdictional boundaries and qualify individually to serve as a GSA within portions of the Sub-Basin per Water Code Section 10723; and F. WHEREAS, under SGMA, a combination of local agencies may elect to form a joint powers authority (“JPA”) to serve as the GSA for all or portions of the Sub-Basin through a joint powers agreement; and
G. WHEREAS, the Members intend by this Agreement to create a JPA to implement SGMA in the entire Sub-Basin, and are authorized to enter into this Agreement pursuant to the Joint Exercise of Powers Act, Government Code §§ 6500 et seq., for the purpose of acting as a separate public agency that can carry out all obligations, and exercise all powers, of a GSA in all areas of the Sub-Basin; and
H. WHEREAS, under SGMA, a GSA, including a JPA composed of one or more SGMA-eligible local agencies, must file a notice of intent with DWR by June 30, 2017 indicating the GSA’s intent to undertake sustainable groundwater management within all or portions of a groundwater basin; and
March 29,
-2-
I. WHEREAS, the governing boards of each of the three Members have formally agreed to: (1) enter into this Agreement; (2) form a JPA that can jointly exercise the powers common to the Members and fulfill all legal obligations imposed by SGMA; and (3) authorize the JPA to promptly file all necessary documentation with DWR so as to permit the JPA to become the exclusive GSA for the entire Sub-Basin; and
J. WHEREAS, the Members further intend by this Agreement to provide for the management and funding commitments reasonably anticipated to be necessary for the above purposes and for the purpose of ensuring that the Sub-Basin is sustainably managed in accordance with the timelines established by SGMA; and
K. WHEREAS, the Members understand that Corona has entered into a Water Enterprise Management Agreement and a Wastewater Enterprise Management Agreement, both dated as of February 6, 2002, with the Corona Utility Authority (“CUA”) for the maintenance, management and operation of those utility systems (collectively “the CUA Management Agreements”). To the extent that this Agreement is deemed to be a “material contract” under either of the CUA Management Agreements, Corona enters into this Agreement on behalf of the CUA and subject to the terms of the applicable CUA Management Agreements.
ACCORDINGLY, IT IS AGREED BY ALL MEMBERS:
1. RECITALS: The foregoing recitals are incorporated as terms of this Agreement.
2. DEFINITIONS: Unless otherwise required by the context, the following terms shall have the following meanings:
a. “Administering Member” shall mean the Member designated by the Authority Board to provide administration, operation and staffing of the Authority so as to ensure the Authority complies with this Agreement and all legal requirements. The Board is not required to designate an Administering Member, and a Member so designated is not required to accept the designation.
b. “Administrator” shall mean the individual selected to act as the chief executive of the Authority, and the person responsible for its day to day operations. The Administrator may, but it is not required to be, an employee of one of the Members. c. “Authority” and “JPA” as used herein shall, unless otherwise noted, mean the “Bedford-Coldwater Groundwater Sustainability Authority,” the separate public agency created by this Agreement and Government Code Sections 6507 and 6508, and the entity charged by this Agreement with becoming the exclusive GSA for the Sub-Basin. d. “Board” or “Board of Directors,” shall, unless otherwise indicated, mean the Board of Directors of the Authority.
e. “DWR” shall mean the California Department of Water Resources. f. “Effective Date” shall mean the date on which all Members have signed this Agreement.
-3-
g. “Fiscal Year” shall run from July 1 through June 30. h. “Groundwater Sustainability Agency” or “GSA” shall mean a groundwater sustainability agency as defined in SGMA, Water Code § 10721. i. “Groundwater Sustainability Plan,” “Plan,” or “GSP” shall have the same meaning as provided in SGMA, Water Code § 10721.
j. “Member” shall mean any of the individual signatories to this Agreement, and “Members” shall collectively mean two or more of the signatories to this Agreement. k. “SGMA” shall mean the Sustainable Groundwater Management Act of 2014, as amended, and any regulations of DWR or the State Water Resources Control Board that implement SGMA.
l. “Special Projects” shall mean projects that are consistent with, and within the scope of activities, authorized by this Agreement, but which are undertaken by fewer than all the Members in the name of the Authority in accordance with the procedures outlined in Sections 10 and 14.
m. “Sub-Basin” shall mean the Bedford-Coldwater Sub-Basin of the Elsinore Groundwater Basin, Sub-Basin No. 8-004.2, as identified in the most recent modifications of Bulletin 118 by DWR.
n. “SWRCB” shall mean the California State Water Resources Control Board.
3. CERTIFICATION: Each Member, as a signatory to this Agreement, certifies and declares that it is a public agency, as defined by Government Code § 6500, that is authorized to enter into a joint powers agreement to contract with each other for the joint exercise of any common power under Article 1, Chapter 5, Division 7, Title 1 of the Government Code or any power otherwise granted to one or more of the Members by SGMA.
4. CREATION OF SEPARATE AGENCY: There is hereby created, per Government Code §§ 6507 and 6508, an agency separate from the parties to the Agreement, and which is responsible for the administration of this Agreement, to be known as the “BEDFORDCOLDWATER GROUNDWATER SUSTAINABILITY AUTHORITY.” Within thirty (30) days of the Effective Date of this Agreement, the Members, and/or the Authority shall: (a) cause a notice of this Agreement to be prepared and filed with the office of the California Secretary of State as required by Government Code § 6503.5; (b) file a copy of this Agreement with the State Controller per Government Code § 6503.6; and (c) file a copy of this Agreement with the Local Agency Formation Commission (“LAFCO”) for Riverside County per Government Code § 6503.6.
5. PURPOSES AND MEMBER RESPONSIBILITIES: The Authority is formed with the purpose and intent of jointly creating a separate legal entity to fulfill the role and legal obligations of a GSA required by SGMA, to include complying with SGMA and ensuring sustainable groundwater management throughout the Sub-Basin, so that the Members may collaboratively and cost effectively develop, adopt, and implement a GSP for the Sub-Basin in
-4-
accordance with pertinent regulatory timelines. The geographic boundaries of the GSA that will be formed by the Authority, which will encompass the entire Sub-Basin, are as depicted in the map attached hereto as Exhibit “A,” which is incorporated herein by reference. The Authority may also represent the Members, as appropriate, in discussions and transactions with other local agencies, to include (but not limited to) the development of inter-basin coordination agreements with other GSAs in Riverside County, and agreements with other local agencies or groundwater sustainability agencies as may be required to ensure compliance with SGMA for the Sub-Basin.
6. POWERS: The Members intend that the Authority provide for the joint exercise of powers common to the Members as such powers relate to the management of the Sub-Basin, and for the exercise of such additional powers as are conferred by law in order to meet the requirements of SGMA. The Members are each SGMA-eligible local agencies empowered by the laws of the State of California to exercise the powers specified in this Agreement, and such other powers as are granted to GSAs by SGMA. These common powers shall be exercised for the benefit of any one or more of the Members or otherwise in the manner set forth in this Agreement. Subject to the limitations set forth in this Agreement, the Authority shall have the powers to perform all acts necessary to accomplish its purposes as stated in this Agreement, as authorized by law, including but not limited to the following:
a. To make and/or assume contracts and to employ agents, employees, consultants and such other persons or firms as the Board may deem necessary, to the full extent of the Authority’s power, including, but not limited to, engineering, hydrogeological, and other consultants, and with attorneys and accountants and financial advisors, for the purpose of providing any service required by the Authority to accomplish its purposes, or to otherwise take such actions as are necessary to ensure the Sub-Basin is managed in accordance with the requirements of SGMA;
b. To conduct all necessary research and investigations, and to compile appropriate reports and collect data from all available sources to assist in preparation and implementation of a GSP, and to support the development of such other agreements as may be necessary to ensure the Sub-Basin can be sustainably managed; c. To cooperate, act in conjunction with, and contract with the United States, the State of California, or any agency thereof, the County of Riverside, or such other entities or persons as the Board may deem necessary to ensure that the Authority fulfills its obligations under SGMA;
d. To apply for, accept and receive licenses, permits, water rights, approvals, agreements, grants, loans, gifts, contributions, donations or other aid from any agency of the United States, the State of California or other public or private person or entity necessary for fulfilling the purposes of SGMA in the Sub-Basin;
e. To acquire by grant, purchase, lease, gift, devise, contract, construction, eminent domain or otherwise, and hold, use, enjoy, sell, let, and dispose of, real and personal property of every kind, including lands, water rights, structures, buildings, rights-of-way, easements, and privileges, and construct, maintain, alter, and operate any and all works or
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improvements, within or outside the agency, necessary or proper to carry out any of the purposes of the Authority as specified in this Agreement and/or the requirements of SGMA; f. To enforce the requirements of SGMA within the Sub-Basin to the extent authorized by law including, but not limited to, the imposition and collection of civil penalties as authorized by SGMA;
g. To sue and be sued in its own name;
h. To provide for the prosecution of, defense of, or other participation in actions or proceedings at law or in public meetings in which the Members, pursuant to this Agreement or otherwise pertaining to management of the Sub-Basin, may have an interest, and to employ counsel or other expert assistance for that purpose; i. To adopt an initial operating budget and initial Member contributions within ninety (90) days of the execution of this Agreement, and an annual budget and Member contributions, by March 31 of each subsequent Fiscal Year; j. To incur debts, liabilities or obligations, subject to the limitations provided in this Agreement;
k. To impose fees authorized by SGMA (Water Code §§ 10730-10731), without any limitation on a Member’s separate ability to impose fees within its jurisdiction, to fund the cost of furthering the purposes of this Agreement, complying with SGMA, and sustainably managing groundwater within the Sub-Basin;
l. To adopt rules, regulations, policies and procedures for governing the operation of the GSA and adoption and implementation of the GSP consistent with the powers and purposes of the Authority and as authorized by SGMA;
m. To investigate legislation and proposed legislation affecting SGMA and the Sub-Basin and make appearances regarding such matters;
n. Subject to the limitations imposed by this Agreement, to take such actions as are deemed necessary by the Board to achieve the purposes stated above and to provide for the sustainable management of the Sub-Basin; and
o. To adopt and revise bylaws, rules, ordinances, and resolutions in a manner authorized by law and not inconsistent with the terms of this Agreement.
Any power necessary or incidental to the foregoing powers shall be exercised by the Authority in the manner provided for under the legal authority applicable to the City of Corona except as otherwise provided by law or in this Agreement.
7. OBLIGATIONS OR LIABILITIES OF AUTHORITY: No debt, liability or obligation of the Authority shall constitute a debt, liability or obligation of any of the Members, except as otherwise provided in this Agreement or unless otherwise required by law.
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8. DESIGNATION OF ADMINISTERING MEMBER/ADMINISTRATOR:
The powers of the Authority provided in this Agreement shall be exercised in the manner provided by this Agreement. The Board may designate an Administering Member and/or an Administrator to provide all or a portion of the administrative (or other) services required by this Agreement, SGMA, or other legal authority. However, whether or not the Board decides to designate an Administering Member, each Member shall nevertheless be responsible, when requested by the Board, for designating staff from their agency to coordinate with the Board and other Members, and for otherwise ensuring the Authority has sufficient staffing and administrative support to comply with this Agreement and other legal obligations.
9. ORGANIZATION:
a. Additional Members: The Board may allow additional members to join the Authority. Additional Members must be local agencies capable of being designated as a GSA under SGMA. The Board may set whatever conditions it deems necessary as a precondition to addition of the new Member, to include requiring the additional Members to reimburse the other Members for a proportionate share of the costs already incurred by the existing Members. b. Bylaws: The Board shall adopt bylaws governing the management of the Authority within 180 days of the Effective Date. The bylaws shall require the Board to develop a conflict of interest code for the Authority compliant with California law, and to otherwise ensure that the Board operates in a manner that is fully compliant with the Brown Act, the Joint Exercise of Powers Act, Government Code §§ 6500 et seq., SGMA, and all other applicable legal requirements.
c. Committees: The Board may create committees as authorized by law. d. Governing Board: The Authority shall be governed by a Board of Directors which shall be composed of one (1) elected representative of each Member, appointed by each Member. The governing body of each Member shall determine in its sole discretion the person it will appoint to the Authority Board of Directors. The Board of Directors shall receive no compensation from the JPA for serving on the Board of the JPA. e. Meetings: Regular meetings of the Board may be held quarterly, or as the Board determines necessary, on such dates and times and at such locations as the Board shall fix by resolution. Special meetings of the Board shall be called in accordance with Government Code § 54956. All meetings of the Board shall comply with the provisions of the Ralph M. Brown Act (Government Code §§ 54950 et seq.).
f. Officers: The officers of the Authority shall be a Chairperson, and ViceChairperson, and such other officers as the Board shall designate. The election of officers will take place at the first meeting of the JPA Board, and subsequently in the first Board meeting of each new Fiscal Year unless the time of election is otherwise designated in the Authority bylaws.
The officers or persons who have charge of, handle or have access to any property of the Authority shall be designated in the bylaws, and such officers and persons shall comply with all applicable requirements of Government Code § 6505.1.
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g. Quorum: Two-thirds (2/3) of the Board of Directors shall constitute a quorum in order to conduct business.
h. Rules: The Board may adopt such other rules, policies, and regulations as it deems proper consistent with all applicable laws, this Agreement, and the Authority’s bylaws. i. Term: The Authority Board Members shall serve without terms and at the pleasure of the legislative body which appointed them.
j. Treasurer: The Treasurer of the Board shall be formally designated by a resolution adopted by the Board of Directors stating the effective date of the appointment and the term of the appointment.
k. Voting: Each Director shall have one vote. A simple majority of the quorum shall be required for the adoption of a motion, resolution, contract authorization or other action of the Board, except that:
(1) A majority vote of less than a quorum may vote to adjourn; (2) Any of the following actions shall require a unanimous vote of the entire Board:
(a) Adoption, modification or alteration of the GSP, or of the GSA boundaries;
(b) Adoption of assessments, charges or fees;
(c) Adoption or modification of ramp-downs or curtailments; (d) Initiation/settlement of enforcement actions;
(e) Adoption of an initial budget;
(f) Adoption or modification of the annual budget, as further described in Section 14, below;
(g) Initiation/termination or settlement of any litigation or threatened litigation that involves the Authority;
(h) Admission of additional Members to the Authority;
(i) Appointment, employment, or dismissal of the Authority’s Administrator and/or Legal Counsel;
(j) Designating an Administrator or Administering Member; (k) Setting the amounts of any contributions or fees to be made or paid to the Authority by any Member, including extraordinary costs as defined in Section 15;
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(l) Acquisition by grant, purchase, lease, gift, devise, contract, construction, or otherwise, and hold, use, enjoy, sell, let, and dispose of, real and personal property of every kind, including lands, water rights, structures, buildings, rights-of-way, easements, and privileges, and construct, maintain, alter, and operate any and all works or improvements, within or outside the agency, necessary or proper to carry out any of the purposes of the Authority; (m) Replacement of the annual special audit required by Government Code § 6505(f) with an audit covering a two year period; (n) Amendments or modifications of this Agreement;
(o) Adoption or modification of bylaws or other binding rules governing the operations of the JPA Board;
(p) Adoption of ordinances;
(q) Issuance of bonds or other indebtedness;
(r) Allocating funding received from grants, loans, or from other alternative sources, in a manner that does not result in equal sharing of alternative funding among the Members;
(s) To apply for, accept and receive licenses, permits, water rights, approvals, agreements, grants, loans, gifts, contributions, donations or other aid from any agency of the United States, the State of California or other public or private person or entity necessary for fulfilling the purposes of SGMA in the SubBasin.
10. SPECIAL PROJECTS AND PROJECT COMMITTEES:
a. With the prior approval of the entire Board, Members may undertake Special Projects in the name of the Authority, utilizing the legal powers granted to the Authority under SGMA, the Joint Exercise of Powers Act, or other applicable legal authorities. All Members shall be given the opportunity to participate in Special Projects, but shall not be required to participate.
b. A Member considering a new project, other than a groundwater extraction project, where the project is reasonably likely to affect groundwater management in the Sub-Basin shall consult with the other Members before individually undertaking the project to determine whether that individual project might otherwise be better accomplished as an Authority Special Project.
c. Members electing to participate in a Special Project shall enter into a Special Project Agreement in accordance with Section 14.a(4) of this Agreement. Such Special Project Agreement shall provide that: (a) no Special Project undertaken pursuant to such agreement shall conflict with the terms of this Agreement or the GSP; (b) the Members to the Special Project Agreement shall indemnify, defend and hold harmless the Authority, and Members
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of the Authority who are not participating in the Special Project, against any costs liabilities, or expenses of any kind arising as a result of the Special Project; (c) all benefits and liabilities attributable to a Special Project shall solely be the benefits and liabilities of the Members that have entered into the Special Project Agreement, and non-participating Members shall have no rights, and incur no obligations or liabilities, in the Special Project.
11. FISCAL AGENT, DEPOSITORY AND ACCOUNTING: The “Treasurer” appointed by the Board is designated as the fiscal agent and depository for the Authority per Government Code §§ 6505.5 and 6505.6. The Treasurer of the Authority shall be the treasurer of one of the Authority’s Members, or a certified public accountant designated by the Board, or an officer or employee designated per Government Code § 6505.6. The Treasurer shall be the depositary and have custody of all money of the Authority, from whatever source, subject to the applicable provisions of any indenture or resolution providing for a trustee or other fiscal agent.
All funds of the Authority shall be held in the operating fund established by Section 14, or such other separate accounts as may be necessary, in the name of the Authority and not commingled with the funds of any Member or any other person or entity. Full books and accounts shall be maintained for the Authority in accordance with generally accepted accounting principles applicable to governmental entities per Government Code §§ 6505 et seq., and any other applicable laws of the State of California.
12. ACCOUNTABILITY, REPORTS AND AUDITS: There shall be strict accountability of all funds, and an auditor designated by the Board shall report any and all receipts and disbursements to the Board with such frequency as shall reasonably be required by the Board.
The Authority will utilize the services of an outside independent certified public accountant to make an annual audit of the accounts and records of the Authority as required by Government Code § 6505, unless the Members, elect to conduct the audit for a two (2) year period. In each case, the minimum requirements of the audit shall be those prescribed by the State Controller for special districts pursuant to Government Code § 26909, and shall conform to generally accepted accounting principles. The outside independent certified public accountant selected by the Authority as auditor shall be formally designated by a resolution adopted by the Board of Directors stating the effective date of the appointment and the term of the appointment.
13. OPERATING BUDGET AND EXPENDITURES: The Board shall adopt a budget as specified in the bylaws and as set forth in Section 14, below. Unless otherwise required by this Agreement or applicable law, the Authority’s Treasurer shall draw checks or warrants or make payments as specified in the bylaws of the Authority. The Authority may, consistent with the bylaws, invest any money in the treasury that is not needed for its immediate necessities.
14. CONTRIBUTIONS/BUDGETS: Unless otherwise provided in this Agreement, the Members shall equally share in the costs of the JPA. The Authority shall establish an operating fund. The fund shall be used to pay all administrative, operating and other expenses incurred by the Authority, and shall be funded by equal Member’s contributions for payment of costs of the Authority. The Board may direct that any surplus funds be returned to the Members, per Government Code § 6512, in proportion to the contributions made by each Member. a. Authority Budgets: Authority budgets shall be established as follows:
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(1) General Operating Budget. No more than ninety (90) days following the first meeting of the Board, and annually thereafter in the month of March or other mutually agreed upon timeframe, a general operation budget (the “Operating Budget”) shall be adopted by the Board. The Operating Budget shall be prepared in sufficient detail to constitute an operating outline for the purpose of establishing rates and/or contributions to be billed to and paid by the Members. The operating rates and/or contributions to be billed to and paid by each Member shall be based upon an equal contribution by each Member. The Operating Budget shall outline anticipated revenues and planned expenditures to be made during the ensuing Budget year by functional category such as operations and maintenance, administration, projects, programs, planning, study and any applicable contributions to operate related reserves. For the purpose of the Operating Budget, operating shall mean any financial activity related to exchange transactions, as defined by applicable generally accepted accounting principles (“GAAP”) associated with the principal activity of the JPA. The Operating Budget shall be adopted by unanimous approval of the Board. The rates and contributions approved by the Board shall be paid by the Members pursuant to Section 14.c below. (2) Non-Operating Budget. No more than ninety (90) days following the first meeting of the Board, and annually thereafter in the month of March or other mutually agreed upon timeframe, a non-operating budget (the “Non-Operating Budget”) shall be adopted by the Board. The Non-Operating Budget shall be prepared in sufficient detail to constitute a non-operating outline for the purpose of establishing rates and/or contributions to be billed to and paid by the Members. These rates and/or contributions shall be based upon equal contributions by each Member. At a minimum, the NonOperating Budget shall outline anticipated revenues and planned expenditures for nonoperating financial activities for the ensuing Fiscal Year, inclusive of any amount necessary for servicing debt. For the purpose of the budget, Non-Operating shall mean any financial activity related to non-exchange transactions, as defined by applicable GAAP. Examples of non-exchange transactions include investment income, contributed capital from Members for capital debt service, interest expense, and return of capital to Members. The Non-Operating Budget shall be adopted by unanimous approval of the Board. The rates and contributions approved by the Board shall be paid by the Members pursuant to Section
14.c below.
(3) Capital Project Budget. No more than ninety (90) days following the first meeting of the Board, and annually thereafter in the month of March, or other mutually agreed upon timeframe, a capital project budget (the “Capital Project Budget”) shall, if applicable, be adopted by the Board. The Capital Project Budget, if applicable, shall be prepared in sufficient detail to constitute a capital project outline to assess contributions to be paid by the Members and expenditures to be paid by the Members during the ensuing year for capital projects needed for major repair, replacement, expansion and efficiency of any capital improvements constructed or installed by or on behalf of the Authority. These contributions shall be based upon equal contribution by each Member, subject to unequal contribution amounts for Special Projects, as addressed in Sections 10 and 14.a.(4). The Capital Project Budget shall be adopted by unanimous approval of the Board. The contributions approved by the Board shall be paid by the Members pursuant to Section 14.c below.
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(4) Special Project Budgets. In addition to the Operating Budgets, the Non-Operating Budgets, and the Capital Project Budget, the Board may budget at any time for the study, implementation or construction of any Special Project, program or study proposed to be undertaken by the Authority for matters not deemed to be of general benefit to all Members. A Special Project budget and written Special Project Agreement of the Members who consented to participation in the Special Project shall be established for each Special Project, which budget and agreement shall determine the respective obligations, functions, and rights of the Members involved and of the Authority. The directors of the Board representing the Members who will be involved in financing and implementing the Special Project shall be and constitute a “Special Project Committee,” for purposes of administration and implementation of the Special Project. No Special Project shall be acquired or constructed by the Board without the consent of each of the governing boards of the participating Members. Ratification of the Special Project budget by each of the participating Members shall constitute consent for the acquisition and construction of the Special Project. Notwithstanding the foregoing, no debt shall be incurred by the Authority for a Special Project without the unanimous consent of the Board. Any rates and contributions approved by the Special Project Committee and approved by the participating Members shall be paid by the participating Members pursuant to Section 14.c below.
Where the Board has approved one or more Special Projects, annually thereafter in the month of March (or other mutually agreed upon timeframe), a Special Project budget shall be developed by each Special Project Committee if required by the applicable Special Project Agreement, Each Special Project budget shall include, without limitation, the following:
(i) Administrative expenses;
(ii) Studies and planning costs;
(iii) Engineering and construction costs;
(iv) The allocation of costs, including debt service costs, if any, among participating Members;
(v) Annual maintenance and operating expenses for the project; and
(vi) A formula for allocating annual maintenance and operating expenses, if any.
All actions by a Special Project Committee shall be deemed actions of the Authority and shall be taken in the name of the Authority, provided, only the participating Members shall have rights and obligations in the Special Project as herein provided.
b. Failure to Obtain Budget Approvals. In the event a budget acceptable to the Board is not approved prior to the start of a Fiscal Year the Authority shall continue to operate at the level of expenditure as authorized below:
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(1) General Operating Budget. The Operating Budget shall be at the expenditure level authorized by the last approved Operating Budget increased by the Consumer Price Index (“CPI”) with a minimum increase of no less than two percent (2%).
The CPI shall mean the change in CPI for Urban Wage Earners and Clerical Workers for the Los Angeles County, Orange County, and Riverside County areas for the all items category for the 12-month period ending the February prior to the beginning of the Fiscal Year budgeted as determined by the U.S. Department of Labor, Bureau of Labor Statistics, or other mutually agreeable source if such a CPI is no longer available. This factor will be applied to the Operating Budget until such time as a new Operating Budget is approved by the Authority. Any shortfall in revenues will be made up from available reserves dedicated by the Board for such a purpose, and if insufficient to cover the shortfall, any available reserve funds not designated by the Board for other purposes or otherwise legally restricted for other purposes by external parties. Reserves shall mean any available cash or investments.
(2) Non-Operating Budget. The Non-Operating Budget shall automatically be established at the required level necessary to meet annual debt service requirements including any revenue coverage covenants. Each Member shall contribute to the Authority such amounts which will yield during each Fiscal Year net revenues payable to the Authority sufficient for the Authority to satisfy all covenants in any indentures, loan agreements or other documents entered into by the Authority and to enter into such other agreements as are necessary for the Authority to secure financing to pay the acquisition price for any facilities authorized by the Authority.
(3) Capital Project Budget. The Capital Project Budget shall automatically be established at the required level necessary to implement capital projects previously approved by the Authority.
c. Payments of Amounts Due. The payments owed for contributions from each Member to the Authority shall be due, payable, and delivered by the Members to the Authority within forty-five (45) days after receipt of a billing therefor from the Authority. To the extent permitted by state law, unpaid and past due contributions shall bear interest at ten percent (10%) per annum, calculated daily, from the date due to the date payment is received by the Authority.
15. ASSESSMENTS FOR EXTRAORDINARY COSTS: In the event the Authority should experience an unanticipated need to pay for extraordinary costs (e.g., those costs that are unanticipated and not otherwise funded through the budget), including, but not limited to the costs of litigation or indemnification as provided in this Agreement, and to the extent that such costs cannot otherwise be reasonably funded through use of reserves on hand or through the other revenue sources authorized by this Agreement, the Board may allocate the additional costs to the Members, whether such extraordinary costs are actually incurred or estimated to be necessary.
Unless otherwise specifically allocated to one or more Members by the unanimous vote of the Board, all allocations of extraordinary costs shall be shared equally by each Member. The Members agree that they will then contribute their proportionate share of the extraordinary costs within a reasonable period of time as determined by the Board, or as otherwise specified in the Bylaws.