City Council / Board of Public Utilities
Liaison Committee
April 28, 2022
Presented by Colin Close
Senior Water Resources Planner
Water Supply Alternatives Plan
2 Outline of presentation
1. Water Supply Alternatives Plan overview
2. Water supply and demand through 2045
3. Resiliency and reliability goals
4. Potential sources of water supply
5. Strategy and scope
6. Draft timeline
7. Recommendation
3 Water Supply Alternatives Plan
will help the City:
Purposefully, systematically, and cost-effectively:
• Adapt to climate change.
• Increase resiliency and reliability of water system.
• Mitigate increasing vulnerability to severe shortages. • Establish local water supply production goals.
• Analyze the feasibility of a range of supply sources. • Leverage the resiliency work of Sonoma Water and the
Con
tractors.
• Determine least-c ost mix of projects to achieve goals. • Document the path forward and implement.
4 Water Supply Alternatives Plan
Purpose
Enhance the City’s long-term water supply resiliency and reliability, to adapt to climate change and reduce
vulnerability to shortages in very dry periods.
Proposed Approach
Conduct a study and develop a plan to:
• Engage stakeholder group for input.
• Establish long-term local water supply goals.
• Determine feasibility of potential supply sources.
• Develop portfolios of options to achieve the goals.
• Prepare and adopt the Plan.
• Implement the Plan to achieve the goals by 2045.
4 5
Existing Water Plans
• Urban Water Management Plan
• Water Shortage Contingency Plan
• Groundwater Master Plan
• Incremental Recycled Water
P
rogram Master Plan
• Santa Rosa Plain Groundwater
Su
stainability Plan
• Sonoma Water Resiliency Study
5 6
Current Supply
29,100 AFY Sonoma Water
2,300 AFY City Wells (Farmers Ln)
140 AFY Regional Recycled Water
31,540 AFY Total
AFY = acre-feet per year
6 7
Normal Water Supply (average rainfall years)
Compared to Projected Demand through 2045
0 5,000
10,000
15,000
20,000
25,000
30,000
35,000
2025 2030 2035 2040 2045
Normal Supply Projected Demand
8 Risk of Severe
Shortage
Storage in Lake Sonoma
remains historically low.
If storage drops below
100k AF, mandated
reductions of 30% or
more can be required.
Climate change is
expected to cause more
frequent and more
severe droughts.
-
50,000
100,000
150,000
200,000
250,000
300,000
Oct-19
Nov-19
Dec-19
Jan-20
Feb-20
Mar-20
Apr-20
May-20
Jun-20
Jul-20
Aug-20
Sep-20
Oct-20
Nov-20
Dec-20
Jan-21
Feb-21
Mar-21
Apr-21
May-21
Jun-21
Jul-21
Aug-21
Sep-21
Oct-21
Nov-21
Dec-21
Jan-22
Feb-22
Mar-22
Apr-22
Lake Sonoma Storage – Acre Feet
30-yr avg (1992-2021) Lowest 1992-2020
100,000 AF Recent Actual
9 30% shortage in Santa Rosa supply is
Stage 5 Water Shortage Emergency.
0 5,000
10,000
15,000
20,000
25,000
30,000
35,000
2025 2030 2035 2040 2045
Normal Supply Stage 5 Supply Projected Demand
7,529 AF
shortage
10 Sonoma Water Restructured Agreement for Water Supply includes local production capacity goal
Section 1.15 Local Production Capacity Goal
In order to mitigate against drought, earthquakes,
spills, temporary impairments, … and other
emergencies that can befall an urban water supply
system,
it is highly desirable that each Water
Contractor achieve and maintain local water
production capacity capable of satisfying
approximately forty percent (40%) of the Water
Contractor’s average day of maximum month
demand
.
11 Existing Local Supply Capacity
Potable wells for drinking water
Recycled water for urban landscapes
Current capacity (five-year averages)
• 1,382 acre-f
eet per year (AFY)
o 7.8% of average annual demand
• 2.75 million gallons per day (MGD)
o 12.5% of average peak day
12 Initial goals for increasing
local supply
Analysis needed to establish feasible goals for
annual (AFY) and peak day production (MGD).
Key drivers:
• Reduce risk for Stage 5-8 shortages
• Respond to Restructured Agreement goal
Start with initial goals and revise (if needed)
during study:
Achieve capacity to locally produce:
• 30% (7,500 AFY) of 2045 annual demand
• 40% (13 MGD) of 2045 average peak day Avg Years Shortage Yrs
WATER SUPPLY GOAL
New Sources
Existing Wells
Recycled
Sonoma Water
13 Potential local water supply sources
Aquifer Storage
& Recovery
Collaborative
resiliency projects
(with Sonoma Water
& Contractors)
Groundwater
Interties Reuse Stormwater
Surface water Water trading Other?
14 Proposed strategy and scope for developing
the Water Supply Alternatives Plan
Study
• Engage stake-
holder group.
• Establish water
supply goals.
• Study feasibility
of potential water
supply sources.
Develop
• Prepare portfolios
of options for
achieving goals by
2045.
• Draft plan.
• Seek input from
stakeholder group
and revise draft.
Adopt
• Hold study
session for broad
public input on
draft Plan.
• Revise as needed.
• Adopt final plan.
Implement
• Fund and execute
the plan over
time to achieve
feasible goals by
2045.
15 Proposed
Timeline
May-Aug 2022
• Solicit proposals, select firm, & award contract.
Sep 2022- Mar 2023
• Engage stakeholders. Conduct study. Draft plan.
Apr-May 2023
• Hold public study session. Finalize plan & adopt.
2024-2045
• Fund & implement projects to achieve the City’s goals. 16 Recommendation
Staff to solicit
proposals, evaluate,
and select firm.
BPU to award
contract.
1 Firm to assist in
conducting study
with stakeholder
input and preparing
plan to achieve
goals by 2045.
2 BPU to hold public
study session to
provide input on
draft plan.
BPU to adopt final
plan.
3 Staff to execute
plan to achieve
goals by 2045.
Staff to report to
BPU periodically on
progress.
4 17
QUESTIONS
& COMMENTS
Colin Close
Senior Water Resources Planner
[email protected]