DRAFT Proposal for Phase 3A of the Upper Santa Ana River Salt and Nutrient Management Strategy Study
Dear Greg,
The Salt and Nutrient Management Plan (SNMP) Working Group selected the WSC/Geoscience Team in 2021 to perform the Upper Santa Ana River Watershed Salt and Nutrient Management Strategy Study (SNMSS). The Study consisted of three phases: Phase 1: Water Quality Characterization; Phase 2: Project Planning and Impact Analysis; and Phase 3: Development of the SNMP. The Team completed Phases 1 and 2 with the work documented in a series of technical memoranda (TMs), culminating in a TM that summarized model assumptions and presented baseline and predictive scenario results for four future alternatives.
The scenarios in Phase 2 evaluated a range of projects and management strategies using the Integrated SAR Water Quality Model. The model results provided TDS projections from 2020 through 2045, which projected that 20% of the TDS assimilative capacity would be consumed between 2039 and beyond 2045, depending on the scenario.
Extrapolation of the projections showed that the Water Quality Objective for TDS would not be exceeded until between 2053 and 2070, depending on the scenario.
As Phase 2 of the SNMSS was being completed in 2023, the Bunker Hill Regional Recycled Water Coalition (Coalition) formed with the primary objective of recharging recycled water into the Bunker Hill B Groundwater Management Zone (BH-B GMZ) to enhance long-term basin sustainability while managing the impacts of salt (as total dissolved solids [TDS]) and nitrate (as N) on ambient water quality (AWQ). In response to a Santa Ana Regional Water Quality Control Board (Water Board) requirement in the Sterling Natural Resource Center recycled water recharge permit, the Coalition commissioned the Bunker Hill Regional Recycled Water Salinity Management Feasibility Study (Feasibility Study) to evaluate a range of salinity management alternatives.
As a result, Phase 2 of the SNMSS ended with a recommendation to pause before beginning Phase 3 while the Coalition completed the Feasibility Study, the results of which would inform the scoping of Phase
3. The Feasibility Study identified that a Regional Desalter would be needed at some point in the future to effectively manage TDS in BH-B GMZ, but also proposed a salinity management framework that emphasized a near
October 16, 2025
San Bernardino Valley
Municipal Water
District
Greg Woodside, PG, CHG
Chief of Planning & Watershed
Resilience
380 East Vanderbilt Way
San Bernardino, CA 92408
WSC Orange County
25201 Paseo De Alicia, STE 290
Laguna Hills, Ca, 92653
P: (949) 528-0960
Michael Cruikshank
P: 714.721.7298
E: [email protected]
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term need for additional data and updated model analyses to inform long term strategies and triggers for implementation of various strategies. Following the updated model analyses, the Feasibility Study identified a decision point for the Coalition (in consultation with the SNMP Workgroup and the Water Board), on whether to proceed with preparation of a Subregional SNMP, or to move forward with implementation of a Regional Desalter as the primary salinity management solution, as summarized in the graphic below, and shown in detail on the Salinity Management Action Timeline included on Page 7 of this proposal.
For the purposes of scoping Phase 3 of the SNMSS for this proposal, we have identified the scope of work needed to get to the decision point as Phase 3A and the scope of work resulting from that decision as Phase 3B. This proposal focuses on Phase 3A because the scope of Phase 3B cannot be confirmed until after Phase 3A is complete.
This Salinity Management Action Timeline was presented to the Water Board on September 30, 2024. The Water Board was generally receptive to the approach and provided two key requests for both the Feasibility Study and the subsequent Implementation Plan:
• Establish interim milestones and check-ins (2025–2027): The Board requested updates to demonstrate progress on the technical work. Since the Water Board is a member of the SNMP Working Group, many of these updates will occur through Workgroup meetings, though the Coalition and the Board may also meet separately on issues specific to the Coalition.
• Clarify model approaches: Provide a description of the Cumulative Antidegradation Model and the SNMP Model, including an explanation of differences in assumptions, methodologies, and results.
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The scope of work proposed herein is referred to as Phase 3A of the SNMSS and intended to address these Water Board requests and the tasks identified in the Salinity Management Action Timeline under the Upper Santa Ana SNMP Workgroup prior to the Subregional SNMP decision point:
1. Update the TDS components of the groundwater model;
2. Model impacts of regional recycled water projects and potential salinity management measures on ambient TDS in the Bunker Hill-B Basin. Potential management measures include a regional desalter, recharge of low TDS water, and best management practices the impacts of regional recycled water projects and potential salinity management measures on ambient TDS in the Bunker Hill B Basin; and
3. Prepare SNMSS Phase 3A Report for submittal to the Regional Board.
Based on the analysis and the Regional Board’s feedback during the process, the SNMSS Phase 3A Report will identify the proposed path forward for the Coalition and SNMP Workgroup, which will serve as the basis of the scope for Phase 3B.
Sincerely,
Water Systems Consulting, Inc.
Michael J. Cruikshank PG, CHG Laine Carlson, PE
Project Manager Principal in Charge
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Scope of Work
Task 0 Project Management
0.1 Project Administration
• Prepare and submit monthly progress reports with each invoice, assuming a 21- month project duration.
0.2 Routine Coordination with Staff of the Coalition
• Conduct monthly one-hour virtual meetings with the Coalition to provide project updates, discuss methodologies, review data needs, present interim results, and address other coordination needs.
• Maintain ongoing communication with Coalition members as needed via phone and email.
Task 1 Groundwater Model Updates
Geoscience was previously tasked by the San Bernardino Valley Municipal Water District (San Bernardino Valley) with constructing a groundwater flow model for the Upper Santa Ana Valley Groundwater Basin by integrating existing groundwater and surface water models. This model, known as the Integrated SAR Model was used as a management tool to determine what factors contribute to reduced streamflow in the SAR and to evaluate potential effects from proposed projects on streamflow and groundwater levels across the basin, including Upper SAR Habitat Conservation Plan (HCP) “Covered Activities”.
The Integrated SAR Model will be used to estimate the probable effects of planned recharge projects on ambient groundwater quality. The model, previously applied in Phases 1 and 2 of the SNMSS, will be updated through 2023 and a revised baseline alternative and up to four project alternatives will be developed, and analyzed. Results from this effort may also support development of a Subregional SNMP, if pursued under Phase 3B.
1.1 Data Collection and Analysis
Geoscience will compile and summarize the volumes and qualities of stormwater and State Water Project water recharged at each percolation basin in the San Bernardino Basin (SBB)_ from 2020 to 2023. Geoscience will utilize this data to extend the record from the 1978 -2019 period previously compiled. The water quality record will be brought through 2023 for stormwater and State Water Project recharge. Water quality data from Ambient Water Quality updates for TDS and nitrate-N will be collected and compiled to extend the observed record through 2023.
1.2 Update Solute Transport Model through 2023
Geoscience was contracted by the San Bernardino Valley Water Conservation District (WCD) to update surface and groundwater flow model portions of the Integrated SAR Model through
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December of 2023 to evaluate WCD recharge activities in the SBB. Geoscience will update the Integrated SAR Model TDS and nitrate-N solute transport models (MT3D-USGS) to cover the period from1966 to 2023 to extend the calibration period of the solute transport models to coincide with the updated surface/groundwater flow models. Model calibration over the new model period from 1966 to 2023 will be evaluated and compared to the previous calibration metrics for both TDS and nitrate-N. The volume-weighted annual average TDS and nitrate concentrations will be calculated and tabulated, as well as concentration of TDS and nitrate-N at observation wells. Then, results will be compared to applicable water quality objectives in the SBBA.
Task 2 Develop and Evaluate Scenarios to Characterize Probable Impacts to Groundwater Quality from
Recycled Water Projects
2.1 Develop Model Scenarios
The Project Team will work with the Bunker Hill-B Coalition and the SNMP Workgroup to confirm the current and planned recycled water projects (including recharge locations, recharge quantities, and recycled water qualities) to be included in the scenario analysis. The most recent groundwater pumping projections from the 2025 Urban Water Management Plans will be incorporated into the groundwater model scenarios. Geoscience will summarize the draft modeling assumptions before preparing the model inputs. Once confirmed, Geoscience will prepare the final model input assumptions and run the model scenarios. Geoscience anticipates incorporating updated project assumptions for the following:
− East Valley Water District's Sterling Natural Resource Center − San Bernardino Water Department’s Tertiary Treatment System − Yucaipa Valley Water District's projects including discharge to San Timoteo Creek − City of Beaumont's discharge to tributaries of San Timoteo Creek − City of Riverside's planned discharges to Reach 3 of the Santa Ana River above MWD crossing (as part of the HCP implementation strategy) − Recharge in Rialto-Colton at Cactus Basins
− Program for Expansion of Recharge Capacity (PERC) Projects − City of Redlands project
2.2 Groundwater Model Runs and Analysis
A baseline scenario model run without any proposed recharge projects will be performed. Flow and transport simulations will be conducted utilizing a monthly stress period. Results from other predictive scenario runs for recycled water projects will be compared to the baseline scenario results to identify net changes of TDS and nitrate concentrations from planned recycled water projects over the next 20 years (or longer planning period selected by the Project Team).
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Upon confirmation of the scenario assumptions, Geoscience will run up to four (4) scenario runs to identify volume-weighted annual average concentrations of TDS and two (2) scenarios for nitrate after implementing planned recycled water projects. The scenario modeling results will be compared to baseline results to identify net changes on average TDS and nitrate concentrations in the receiving groundwater basins expected to occur as a result of these planned recycled water recharge projects over the planning period. Results from this modeling and analysis effort will include:
• Model-predicted TDS and nitrate concentrations through time with and without recycled water project(s);
• Volume-weighted annual average, rolling 5-year, 10-year, and 20-year average TDS and nitrate concentrations for the baseline run and each scenario run in the applicable GMZs and the larger SBBA GMZ; and
• Chemographs for TDS and nitrate at water supply wells showing recycled water project local impacts on downstream drinking water wells. • Detailed annual water budget analysis including:
o A table summarizing the water budget by year for baseline and each scenario;
o A mass balance table for the BH-B MZ by year for baseline and each scenario;
o Identification of all model locations where TDS or nitrate concentrations are specified; and
o Documentation of any boundary conditions applied in the model for TDS or nitrate.
2.3 Draft and Final Phase 3A Modeling Technical Memorandum Geoscience will prepare a Draft and Final Phase 3A Modeling TM. Results from Tasks 1 and 2 will be summarized in the Draft TM. An electronic copy (i.e., PDF) will be provided and presented to the Coalition and the SNMP Workgroup for review and comment. Upon incorporation of any comments, Geoscience will submit an electronic copy of the Final TM.
Deliverables: Draft and Final Modeling Technical Memorandum
Task 3 SNMSS Phase 3A Report
WSC will prepare a report summarizing the analyses from Phase 1 and Phase 2 of the previous SNMSS work, the Phase 3A modeling report from Tasks 1 and 2 of this effort, and the implications for long term salinity management. The Report will build on the results of the Feasibility Study and the SNMSS work and provide an updated evaluation of the benefits and impacts of pursuing a Subregional SNMP in comparison to implementing a Regional Desalter.
The Report will present a proposed path forward for salinity management in BH-B MZ. If the proposed path forward includes making a request to the Water Board for use of more than 20% of the assimilative capacity (AC) based on the results from the modeling work, the Report will
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also define the necessary commitments and actions, including establishing an action trigger for initiating the Regional Desalter Final Design in coordination with Water Board Staff.
Deliverables: Draft and Final Report
Task 4 Stakeholder Meetings
4.1 Meetings with the SNMP Workgroup
• Conduct a total of five (5) SNMP Workgroup meetings—two in-person and three virtual (via Teams)—scheduled around key decision points such as discussion of model scenario assumptions, review of model results, and release of draft technical memoranda or reports.
4.2 Meetings with Regional Board Staff
• Prepare for Regional Board staff meetings in coordination with Coalition staff. • Conduct two in-person meetings with Regional Board staff to discuss the modeling approach, review model results, and discuss the utilization of assimilative capacity.
Optional Task 1 Additional Solute Transport Model
Calibration (Optional Task)
Geoscience will perform and analyze up to five (5) additional solute transport model calibration runs, in consultation with the Coalition, if the model update assessment indicates that further calibration is needed. An iterative process will be used, with intermediate calibration results evaluated and shared with the project team throughout the effort.
Optional Task 2 Evaluate Two Alternative Scenarios for TDS and One Alternative Scenarios for
Nitrate-N to Characterize Probable
Impacts to Groundwater Quality from
Recycled Water Projects In Bunker Hill A
(Optional, As-Needed)
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To evaluate alternatives in Bunker Hill-A, Geoscience will run up to two (2) scenario runs to identify volume-weighted annual average concentrations of TDS after implementing planned Bunker Hill A projects. The scenario modeling results will be compared to baseline results to identify net changes on average TDS concentrations in the receiving groundwater basins that are expected to occur as a result of planned project alternatives over the next 20 years.
Following the TDS runs, Geoscience will perform one (1) nitrate-N simulation of the preferred alternative.
Results from this modeling and analysis effort will include:
• Model-predicted TDS and nitrate concentrations through time with and without recycled water project(s);
• Volume-weighted annual average, rolling 5-year, 10-year, and 20-year average TDS and nitrate concentrations for the baseline run and each scenario run in the applicable GMZs and the larger SBBA GMZ; and
• Chemographs for TDS and nitrate at water supply wells showing recycled water project local impacts on downstream drinking water wells.
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Schedule
J F M A M J J A S O N D J F M A M J J A S
Routine Coordination with Staff of the Coalition
Task 1.1 Data Collection and Analysis
Task 1.2: Update Solute Transport Model through 2023
Task 2.1: Develop Model Scenarios
Task 2.2: Groundwater Model Runs and Analysis
Task 2.3: Draft and Final Modeling Technical Memorandum TM TM Task 3.1: Prepare Draft and Final Report TM TM
Task 4.1: Meetings with SNMP Workgroup ( 5 Total Meetings) KO 1 2 3 4 Task 4.2: Meetings with the Santa Ana Regional Water Quality Control Board Optional Task 1: Additional Solute Transport Model Calibration Optional Task 2: Evaluate Two Alternative Scenarios for TDS and One Alternative Scenarios for Nitrate-N to Characterize Probable Impacts to Groundwater Quality from Recycled Water Projects In Bunker Hill A Task 4: Stakeholder Meetings
Task 0: Project Management
Optional Tasks
Task 1: Groundwater Model Updates
Task 2: Develop and Evaluate Scenarios to Characterize Probable Impacts to Groundwater Quality from Recycled Water Projects Task 3: Phase 3A Bunker Hill-B GMZ Salinity Management Strategy Study Report TASKS
2026 2027
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Fee Estimate