City Council
October 24, 2023
Colin Close
Senior Water Resources Planner
Our Water Future:
Water Supply Alternatives Plan
2 Water Supply Alternatives Plan
Purpose
Enhance Santa Rosa’s water supply
resiliency and reliability to mitigate
impacts of shortages due to severe
droughts and emergencies.
Approach
Assess the feasibility of new water
supply options and develop a plan
for increasing resiliency.
3 Key Considerations Guiding the Project
• How much new water supply is optimal
to mitigate the risk of shortages?
• Which supply options should be studied?
• What criteria should be used to assess
each supply option?
• Which mix(es) of options will best help
us meet our supply resiliency goal?
• What is the most reasonable and
adaptive path forward?
Study
Portfolios
Plan
4 Project Overview
ENGAGE STAKEHOLDERS
Get input from a wide range of stakeholders,
including our community.
SET OBJECTIVES
Set water supply goals, identify potential supply
options, establish criteria and study methods.
STUDY SUPPLY OPTIONS
Study feasibility of potential water supply options.
Develop and assess portfolios of feasible options.
DEVELOP A PLAN
Develop long-term plan for achieving supply goals.
5 Overview of Plan
Acknowledgements
Executive Summary
Ch 1: Introduction
Ch 2: Approach to Developing the WSAP
Ch 3: Water Supply Options
Ch 4: Analysis of Water Supply Options
Ch 5: Portfolios
Ch 6: Next Steps
Appendices
6 Acknowledgements
• Water Team
• Stakeholder Group
• Community
STAKEHOLDER GROUP
1. Calpine
2. Community Action Partnership
3. Los Cien Sonoma County
4. NAACP Santa Rosa
5. North Bay Black Chamber of Commerce
6. North Coast Builders Exchange
7. Recycled Water User – Ag
8. Recycled Water User – Urban
9. RED Housing Fund
10. Regional Climate Protection Authority
11. Russian River Watershed Association
12. Russian River Water Protection Committee
13. Santa Rosa Metro Chamber of Commerce
14. Santa Rosa Plain Groundwater Sustainability Agency
15. Santa Rosa Subregional TAC
16. Sonoma Clean Power
17. Sonoma County Alliance
18. Sonoma RCD
19. Sonoma Water
6 7
Chapter 1: Background, Purpose, Plan
Organization
• Santa Rosa currently receives 93% of its annual potable water supply from Sonoma Water, which relies on the Russian River system for 95- 99% of its supply.
• Santa Rosa Water is looking to expand and diversify its potable water supply portfolio to enhance its resiliency to mitigate the potential impacts of future Sonoma Water supply shortages or catastrophic service interruptions.
• The WSAP is organized into six chapters as well as an acknowledgments section, executive summary, and seven appendices.
8 Chapter 2: Approach to
Developing Water Supply
Alternatives Plan
• Stakeholder engagement
• Goal and volumetric targets
• Study methodology
9 Stakeholder
Engagement
Water Team
• 5 working sessions (Oct, Dec, May, Jul, Aug).
• Input on study parameters, results, portfolios, & Plan.
Stakeholder Group
• 4 working sessions (Nov, Dec, May, July).
• Input on study parameters, results, portfolios, & Plan.
Community
• 4 community webinars (Oct, Jan, Jun, Aug).
• Input on study parameters, study results, portfolios, & Plan.
Board of Public Utilities
• Updates, study sessions, review of Plan.
• Input on study parameters, results, portfolios, & Plan.
10 Mitigating Droughts Mitigating Natural Disasters &
Catastrophic Events Mitigating Peak Day Demand
Meet 30% of City’s water demand
with municipal supplies to mitigate
impacts of Russian River supply
shortages (e.g., due to prolonged
and/or severe drought).
Based on current City demand
projections, the volume of water
required to meet this is 7,500 acre-
feet per year (AFY) by 2045.
Provide 50% of normal
domestic/indoor demand for
potable water with municipal
supplies during Russian River supply
disruption.
Based on current City demand
projections, the volume of water
required to meet this is 9 million
gallons per day (MGD) by 2045.
Meet 30 percent of peak month
average day demand for potable
water with municipal supplies.
Based on current City demand
projections, the volume of water
required to meet this is 9 MGD by
2045.
Water Supply Goal and Targets
GOAL: Diversify and increase city supplies to reduce dependence on Sonoma Water, particularly during Sonoma Water supply shortages or disruption in delivery 11 Analysis Methodology
Three stage evaluation of water supply options:
1. Pre-Screening to eliminate infeasible options and those substantially similar to other proposed or existing projects.
2. Screening Analysis based on cost-effectiveness and scalability under a range of operating assumptions.
3. Feasibility Analysis to evaluate and score remaining options across a range of criteria reflective of community priorities.
12 Chapter 3: Water Supply Options
Groundwater
GW-1 Additional groundwater extraction wells
GW-2 Conversion of emergency wells to production
GW-3 Aquifer Storage and Recovery (ASR) wells
GW-4 Regional groundwater extraction wells
GW-5 Regional Aquifer Storage and Recovery wells
Purified Recycled Water
PR-1 Produce at LTP for direct potable reuse (DPR)
PR-2 Produce at a satellite location (DPR)
PR-3a Produce at LTP and inject into groundwater
via ASR wells for indirect potable reuse (IPR)
PR-3b Produce at LTP and add to Lake Ralphine
before use (IPR)
PR-3c Produce at LTP and add to Lake Sonoma (or
alternate) before use (IPR)
PR-4 Regional purified recycled water (DPR)
Nonpotable Recycled
RW-1 Expand Nonpotable Recycled Water Service (City)
Desalination
DE-1 Brackish desalination (likely Regional)
DE-2 Ocean desalination (Santa Rosa or Regional)
Surface/Stormwater
SW-1 Capture excess winter flows from Santa Rosa
Creek/Laguna de Santa Rosa, store in aquifer for
later withdrawal
SW-2 Store excess winter flows from Santa Rosa
Creek/Laguna de Santa Rosa, store in enlarged
Lake Ralphine, construct water treatment plant to
withdraw from Lake Ralphine
SW-3 Regional Stormwater
Efficiency Programs
E-1 Aggressive incentives for toilets & turf replacement 12 13
Chapter 4: Analysis of Water Supply Options
Pre-screening process
– 5 options did not advance
• Regional groundwater extraction
• Regional ASR
• IPR into Lake Ralphine
• Stormwater storage in Lake Ralphine
• Regional stormwater
Screening process
– 6 options did not advance
• DPR AWPF at LTP
• IPR AWPF at LTP via Delta Pond
• IPR AWPF at LTP via Lake Sonoma
• Expand City’s existing non-potable
recycled water system
• Regional brackish desalination
• Ocean desalination
1414
7 Options Underwent Further Analysis
• Add Extraction Wells
• Convert Emergency Wells to Production Wells
• Add Aquifer Storage & Recovery Wells
• Satellite Direct Potable Reuse
• Regional Direct Potable Reuse at Laguna Treatment Plant • Stormwater Storage in Aquifer
• Efficiency Programs
15 Feasibility Analysis Results (Higher Score is Better) Criterion
Groundwater Purified Recycled Water Stormwater
Efficiency
Programs
Add
Extraction
Wells
Convert
Emergency
Wells
Add City ASR
Wells
City Direct
Potable
Reuse
Regional Direct
Potable Reuse
Stormwater
Storage in
Aquifer
Cost effectiveness 2 2 2 0 0 0 1
Scalability 2 0 1 2 2 1 1
Resiliency 1 1 2 2 2 1 1
Equity 1 1 1 1 1 1 2
Environmental
performance 1 2 1 0 1 1 2
Legal, permitting, &
regulatory 1 2 0 0 0 1 2
City control &
interagency coord 2 2 1 2 0 2 2
Multi-benefit 0 0 1 0 0 2 1
Total Unweighted 10 10 9 7 6 9 12
Total Weighted 32 26 29 21 22 19 30
15 16
Chapter 5: Portfolios
• Portfolio composition – what is in the portfolio?
• Rationale – why build a portfolio like this?
• Cost and yield performance – how does the
portfolio perform financially and against our
water supply goals?
• Implementation timeline – how might we
implement this portfolio? when and in what
order would portfolio elements be completed?
Increasing
resiliency & reliability
Water
efficiency
Purified
water
Extraction
wells
17 Portfolios
Description
Portfolio 1
Most
Economical
Portfolio 2
Fastest
Portfolio 3
Most Water
Portfolio 4
Most Adaptive
Add Extraction Wells (Up to 12)
Convert Emergency Wells to
Production Wells
Add Aquifer Storage & Recovery Wells Consider
Satellite Direct Potable Reuse Consider
Regional Direct Potable Reuse at
Laguna Treatment Plant Consider
Stormwater Storage in Aquifer Consider Consider
Efficiency Programs
Desalination Reconsider
18 Chapter 6: Next Steps
• Identify funding opportunities for initial steps.
• Plan for Phase 1 of efficiency programs.
• Begin hydrogeologic studies and CEQA pathway
for groundwater options.
• Prepare siting study for groundwater options.
• Track changes in regulations, technology, funding
opportunities, and regional opportunities.
• Initiate planning studies for additional supply
options as needed.
• Reconsider desalination at key decision points.
19 Appendices
A: Feasibility Analysis Technical Memorandum
B: Links to Recorded Meetings
C: Portfolio 1 Example Schedule
D: Portfolio 2 Example Schedule
E: Portfolio 3 Example Schedule
F: Portfolio 4 Example Schedule (Baseline Scenario)
G: Portfolio 4 Example Schedule (Alternative Scenario)
H: Santa Rosa Water’s Recent Budgets for Operations and Capital Projects I: Memorandum on Desalination Supply Options
20 Recommendation
It is recommended by Santa Rosa
Water and the Board of Public
Utilities, that the City Council, by
motion, accept the Water Supply
Alternatives Plan.
21 Questions?