Sonoma City Council
June 17, 2026

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-5 EKI Environment & Water, Inc.
term water supply emergency in which case the water from the wells would be tested to ensure primary MCLs are met.

Given the City’s proactive monitoring and management of water quality in its source water supplies, water quality is not expected to impact the reliability of the City’s available supplies within the planning horizon (i.e., through 2050).

7.1.3 Climate Change
 CWC §10631 (b) (1)
…For each source of water supply, consider any information pertinent to the reliability analysis conducted pursuant to Section 10635, including changes in supply due to climate change.

As discussed in Section 6.10.1, Sonoma Water’s Climate Adaptation Plan, completed in 2021, identifies vulnerability and risk to water supply system components, and identifies projects that can be implemented to address the risks. The Sonoma Valley Subbasin GSP incorporated climate change into the basin water budget and identified projects and actions to sustainably manage the basin under these conditions. Based on the analyses described in these plans, climate change may be expected reduce supplies available and potentially impact water system facilities, but the projects and actions identified in the plans incorporate these considerations to ensure that supplies are reliable into the future.

7.2 Reliability by Type of Year
 CWC §10631 (b)
Identify and quantify, to the extent practicable, the existing and planned sources of water available to the supplier over the same five-year increments described in subdivision (a), providing supporting and related information, including all of the following:
 CWC §10631 (b)(1)
A detailed discussion of anticipated supply availability under a normal water year, single dry year, and droughts lasting at least five years, as well as more frequent and severe periods of drought, as described in the drought risk assessment. For each source of water supply, consider any information pertinent to the reliability analysis conducted pursuant to Section 10635, including changes in supply due to climate change.  CWC §10635 (a)
Every urban water supplier shall include, as part of its urban water management plan, an assessment of the reliability of its water service to its customers during normal, dry, and multiple dry water years. This water supply and demand assessment shall compare the total water supply sources available to the water supplier with the long-term total projected water use over the next 20 years, in five-year increments, for a normal water year, a single dry water year, and a drought lasting five consecutive water years. The water service reliability assessment shall be based upon the information compiled pursuant to Section 10631, including available data from state, regional, or local agency population projections within the service area of the urban water supplier.

Consistent with the 2025 UWMP Guidebook, the water service reliability assessment includes three unique types of years based on hydrologic conditions:
• A normal hydrologic year represents the water supplies available under normal conditions; this could be an average over a range of years or a single representative year, • A single dry year represents the lowest available water supply, and • A five-consecutive year drought represents the driest five-year period in the historical record.

Identification of these dry year periods consistent with the UWMP Guidebook 2025 methodology is provided below.

Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-6 EKI Environment & Water, Inc.

Table 7-1 Basis of Water Year Data (Reliability Assessment) (DWR Table 7-1) Available Supplies if Year Type
Repeats
☒
Checked box indicates quantification
of available supplies is not compatible
with this table and is provided
elsewhere in the UWMP.

Location: Section 7.2.1 through 7.2.3.

Year Type
Base
Year
Volume
Available % of Average Supply
Average Year 1999 100%
Single-Dry Year 1977
Consecutive Dry Years 1st Year 1987
Consecutive Dry Years 2nd Year 1988
Consecutive Dry Years 3rd Year 1989
Consecutive Dry Years 4th Year 1990
Consecutive Dry Years 5th Year 1991

7.2.1 Purchased Water
The projected availability of purchased water supply by hydrologic year type is summarized in Table 7-2. Sonoma Water’s 2025 UWMP concludes that sufficient water supplies are available to meet projected demands under all hydrologic conditions through 2050. However, the City’s projected demand for purchased water was used in Sonoma Water’s modeling, and is less than the full contracted entitlement.

Accordingly, the purchased water reliability assessment assumes that the City’s full contracted amount would be available during normal hydrologic years. In single dry years and extended drought conditions, the volume of purchased water available is assumed to be the remaining potable demand after groundwater supplies have been utilized.

Table 7-2 Projected Availability of Sonoma Water Supply (Responds to DWR Table 7-1) Year Type Base year 2030 2035 2040 2045 2050
Normal Year 1999 3,000 3,000 3,000 3,000 3,000
Single-Dry Year 1977 1,931 1,914 1,905 1,900 1,899
Extended Drought
First year 1987 1,931 1,914 1,905 1,900 1,899
Second year 1988 1,931 1,914 1,905 1,900 1,899
Third year 1989 1,931 1,914 1,905 1,900 1,899
Fourth year 1990 1,931 1,914 1,905 1,900 1,899
Fifth year 1991 1,931 1,914 1,905 1,900 1,899
NOTES:
(a) Sonoma Water supplies reflect projected purchases and does not reflect full contracted rights which are 3,000 AFY for the City.
(b) Volumes are in units of AF.

Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-7 EKI Environment & Water, Inc.

7.2.2 Local Groundwater
The projected availability of groundwater supply by hydrologic year type is summarized in Table 7-3.

Supply availability for local groundwater is assumed to not be impacted in dry years. The City anticipates using groundwater to the extent that it is replenished without impacting long-term groundwater levels.

Table 7-3 Projected Availability of Local Groundwater Supply (Responds to DWR Table 7-1) Year Type Base year 2030 2035 2040 2045 2050
Normal Year (a) 238 238 238 238 238
Single-Dry Year (a) 238 238 238 238 238
Extended Drought
First year (a) 238 238 238 238 238
Second year (a) 238 238 238 238 238
Third year (a) 238 238 238 238 238
Fourth year (a) 238 238 238 238 238
Fifth year (a) 238 238 238 238 238
NOTES:
(a) Groundwater supply in the Sonoma Valley Subbasin is assumed to not be impacted in dry years and therefore no years are listed here. Supply is equal to the City’s safe yield as described in its 2018 Master Plan. (b) Volumes are in units of AF.

7.2.3 Recycled Water
The projected availability of recycled water supply by hydrologic year type is summarized in Table 7-4.

Supply availability for recycled water is assumed to not be impacted in dry years. The City anticipates using recycled water equal to projected demands.

Table 7-4 Projected Availability of Recycled Water Supply (Responds to DWR Table 7-1) Year Type Base year 2030 2035 2040 2045 2050
Normal Year (a) 21 21 21 21 21
Single-Dry Year (a) 21 21 21 21 21
Extended Drought
First year (a) 21 21 21 21 21
Second year (a) 21 21 21 21 21
Third year (a) 21 21 21 21 21
Fourth year (a) 21 21 21 21 21
Fifth year (a) 21 21 21 21 21
NOTES:
(a) Recycled water is assumed to not be impacted in dry years and therefore no years are listed here. Supply is equal to projected non-potable demands.
(b) Volumes are in units of AF.

Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-8 EKI Environment & Water, Inc.

7.3 Supply and Demand Assessment
 CWC §10635(a)
Every urban water supplier shall include, as part of its urban water management plan, an assessment of the reliability of its water service to its customers during normal, dry, and multiple dry water years. This water supply and demand assessment shall compare the total water supply sources available to the water supplier with the long-term total projected water use over the next 20 years, in five-year increments, for a normal water year, a single dry water year, and a drought lasting five consecutive water years. The water service reliability assessment shall be based upon the information compiled pursuant to Section 10631, including available data from state, regional, or local agency population projections within the service area of the urban water supplier.

Water supply and demand patterns change during normal, single dry, and multiple dry years. Table 7-5 shows the projected supply and demand totals for a normal year. The supply and demand totals are consistent with those in Table 4-5 and Table 6-11, respectively. Table 7-6 shows the projected supply and demand totals for the single dry year, and Table 7-7 shows the projected supply and demand totals for multiple dry year periods extending five years.

Table 7-5 Normal Year Supply and Demand Comparison (DWR Table 7-2) 2030 2035 2040 2045 2050
Supply totals
(from Table 6-11 [DWR Table 6-
9])
3,259 3,259 3,259 3,259 3,259
Use totals
(from Table 4-5 [DWR Table 4-2]) 2,190 2,173 2,164 2,159 2,158 Surplus/(shortfall) 1,069 1,086 1,095 1,100 1,101
NOTES: Volumes are in units of AF.

Table 7-6 Single Dry Year Supply and Demand Comparison (DWR Table 7-3) 2030 2035 2040 2045 2050
Supply totals 2,190 2,173 2,164 2,159 2,158
Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
NOTES: Volumes are in units of AF.

Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-9 EKI Environment & Water, Inc.

Table 7-7 Five Consecutive Dry Years Supply and Demand Comparison (DWR Table 7-4) 2030 2035 2040 2045 2050
First year Supply totals 2,190 2,173 2,164 2,159 2,158
Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
Second year Supply totals 2,190 2,173 2,164 2,159 2,158 Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
Third year Supply totals 2,190 2,173 2,164 2,159 2,158
Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
Fourth year Supply totals 2,190 2,173 2,164 2,159 2,158 Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
Fifth year Supply totals 2,190 2,173 2,164 2,159 2,158
Use totals 2,190 2,173 2,164 2,159 2,158
Surplus/(shortfall) 0 0 0 0 0
NOTES: Volumes are in units of AF.

Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-10 EKI Environment & Water, Inc.

7.4 Water Supply Management Tools and Options
 CWC §10620 (f)
An urban water supplier shall describe in the plan water management tools and options used by that entity that will maximize resources and minimize the need to import water from other regions.

The City is a member of the SMSWP, which is a regional partnership program that represents twelve utilities in Sonoma and Marin counties that have joined together to provide a regional approach to water use efficiency. Participating in the partnership, the City also continues to implement an extensive water conservation program, which reduces the demand on imported supplies. As described in Chapter 9, the City manages per capita water use through the implementation of a series of demand management measures.

7.5 Drought Risk Assessment
 CWC §10635(b)
Every urban water supplier shall include, as part of its urban water management plan, a drought risk assessment for its water service to its customers as part of information considered in developing the demand management measures and water supply projects and programs to be included in the urban water management plan. The urban water supplier may conduct an interim update or updates to this drought risk assessment within the five-year cycle of its urban water management plan update. The drought risk assessment shall include each of the following:
(1) A description of the data, methodology, and basis for one or more supply shortage conditions that are necessary to conduct a drought risk assessment for a drought period that lasts five consecutive water years, starting from the year following when the assessment is conducted.
(2) A determination of the reliability of each source of supply under a variety of water shortage conditions. This may include a determination that a particular source of water supply is fully reliable under most, if not all, conditions. (3) A comparison of the total water supply sources available to the water supplier with the total projected water use for the drought period.
(4) Considerations of the historical drought hydrology, plausible changes on projected supplies and demands under climate change conditions, anticipated regulatory changes, and other locally applicable criteria.

In addition to the long-term water service reliability assessment presented above, the Drought Risk Assessment evaluates City’s supply risks under a severe drought period lasting for the next five consecutive years after the assessment is completed, i.e., from 2026 through 2030. The Drought Risk Assessment is intended to inform the demand management measures and water supply projects and programs to be included in the UWMP (Section 9). Suppliers may conduct an interim update or updates to this Drought Risk Assessment within the five-year cycle of its UWMP update (i.e., before the 2030 UWMP).

7.5.1 Data, Methods, and Basis for Water Shortage Condition This evaluation considers historical drought hydrology and plausible changes on projected supplies and demands under climate change conditions, anticipated regulatory changes, and other locally applicable criteria.

As a first step to the Drought Risk Assessment, City estimated unconstrained water demand for the next five years (i.e., 2026-2030). Unconstrained water demand is the expected water use in the absence of drought water use restrictions. The characteristic five-year water demand is described in Section 4.5.5.

The available potable water supplies assumed in the Drought Risk Assessment are based upon the same methodology and assumptions used for the long-term water service reliability assessment (Section 0) and Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-11 EKI Environment & Water, Inc.
rely on information provided by Sonoma Water’s UWMP and the Sonoma Valley Subbasin GSP. The approach for estimating City’s available supplies follow below, as part of the Drought Risk Assessment.

7.5.2 Drought Risk Assessment Individual Water Source Reliability As described in Chapter 6, the City relies on purchased water from Sonoma Water, groundwater from the Sonoma Valley Subbasin, and recycled water from SVCSD.

The City’s available supplies during the five-consecutive-year drought are based on the results of modeling completed by Sonoma Water which states that sufficient supply is available to meet retailer demands under drought risk assessment conditions, and through review of the Sonoma Valley Subbasin GSP which explored groundwater storage under varying hydrologic conditions.

7.5.3 Drought Risk Assessment Total Water Supply and Use Comparison Table 7-8 provides a comparison of the water supply sources available to the City with the total projected water use for an assumed drought period of 2026 through 2030.

The City’s supply is expected to be sufficient to meet demands in all hydrologic conditions, including an extended five-year drought period. Table 7-8 also summarizes planned WSCP actions that the City will implement to augment supply and/or reduce demands (see Appendix E).

Table 7-8 Five-Year Drought Risk Assessment (DWR Table 7-5) 2026 Total
Total Water Use 2,020
Total Supplies 2,020
Surplus/Shortfall without WSCP Action 0
2027 Total
Total Water Use 2,063
Total Supplies 2,063
Surplus/Shortfall without WSCP Action 0
2028 Total
Total Water Use 2,105
Total Supplies 2,105
Surplus/Shortfall without WSCP Action 0
2029 Total
Total Water Use 2,148
Total Supplies 2,148
Surplus/Shortfall without WSCP Action 0
Agenda Item #8.1:

Section 7 2025 Urban Water Management Plan
Water Supply Reliability Assessment City of Sonoma
PUBLIC DRAFT | May 2026
7-12 EKI Environment & Water, Inc.

Table 7-5 (continued) Five-year Drought Risk Assessment 2030 Total
Total Water Use 2,190
Total Supplies 2,190
Surplus/Shortfall without WSCP Action 0
NOTES: Volumes are in units of AF.

Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
8-1 EKI Environment & Water, Inc.
8 WATER SHORTAGE CONTINGENCY PLANNING
 CWC §10640
(a) Every urban water supplier required to prepare a plan pursuant to this part shall prepare its plan pursuant to Article 2 (commencing with Section 10630). The supplier shall likewise periodically review the plan as required by Section 10621, and any amendments or changes required as a result of that review shall be adopted pursuant to this article.
(b) Every urban water supplier required to prepare a watershortage contingency plan shall prepare a watershortage contingency plan pursuant to Section 10632. The supplier shall likewise periodically review the water shortage contingency plan as required by paragraph (10) of subdivision (a) of Section 10632 and any amendments or changes required as a result of that review shall be adopted pursuant to this article.

The City’s WSCP is included as Appendix E. The WSCP serves as a standalone document to be engaged in the case of a water shortage event, such as a drought or supply interruption, and defines specific policies and actions that will be implemented at various shortage level scenarios. The primary objective of the WSCP is to ensure that the City has in place the necessary resources and management responses needed to protect health and human safety, minimize economic disruption, and preserve environmental and community assets during water supply shortages and interruptions. Consistent with CWC §10632, the WSCP includes six levels to address shortage conditions ranging from up to 10 percent to greater than 50 percent shortage, identifies a suite of demand mitigation measures for the City to implement at each level, and identifies procedures for the City to annually assess whether a water shortage is likely to occur in the coming year, among other things.

A summary of the key elements of the WSCP including water shortage levels and demand-reduction actions is shown in Table 8-1, Table 8-2, and Table 8-3. Additional details are provided in Appendix E.

Table 8-1 Cross-reference for Standard vs Supplier Shortage Levels (DWR Table 8-1) ☒ Checked box indicates the supplier uses the standard six levels of water shortage (and supplier will not complete this table).

Standard Shortage
Levels
Percent Shortage
Range
Suppliers Shortage
Levels
Percent Shortage
Range
1 Up to 10%
2 Up to 20%
3 Up to 30%
4 Up to 40%
5 Up to 50%
6 >50%
Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
8-2 EKI Environment & Water, Inc.

Table 8-2 Supply Augmentation and Other Actions (DWR Table 8-2) Shortage
Level (a)
Supply Augmentation
Methods and Other Actions
by Water Supplier
Volume or
Percentage of
Shortage Gap
Reduction
Shortage Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
1 Expand Public Information
Campaign Percentage 0.5%
The City will implement media campaigns, including:
• Publicize the water shortage and conservation measures using a media campaign, newspaper articles, and website. • Promote water conservation programs.
• Hold water efficiency workshops and public events.
1 Expand Public Information
Campaign Percentage 0.5% Distribute water bill inserts with information about water shortage and conservation. 2 Other Actions (describe) Percentage 1% Continue with action and measures from Stage 1 except where superseded by more stringent requirements.
2 Other Actions (describe) Percentage 4% Accelerate leak detection and repair program. 2 Other Actions (describe)
Percentage
2%
Suspend routine flushing of water mains except when necessary to address immediate health or safety concerns or when flushing can be conducted without discharge
2 Other Actions (describe) Percentage 1% Reduce distribution system pressures 3 Other Actions (describe) Percentage 8% Continue with action and measures from Stage 2 except where superseded by more stringent requirements.
3 Implement or Modify Drought
Rate Structure or Surcharge Percentage 4% The City will implement drought rate structure / water budget. 4 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 3 except where superseded by more stringent requirements.
5 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 4 except where superseded by more stringent requirements.
6 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 5 except where superseded by more stringent requirements.
6 Other Actions (describe) Percentage 3% Increase staff enforcement to ensure customers complying with the assigned water budget.

Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
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Table 8-3 Demand Reduction Actions (DWR Table 8-3)
yes Is the Supplier completing this table using the standard six levels? (yes/no) Shortage
Level
Demand Reduction
Actions
How much is this going to
reduce the shortage gap? Additional Explanation or Reference (OPTIONAL)
Penalty, Charge,
or Other
Enforcement? Volume or
Percentage
Shortage Gap
Reduction
Value
1 Other - Prohibit use
of potable water for
washing hard
surfaces
Percentage 0.5%
Washing sidewalks, walkways, driveways, parking lots and other hard-surfaced areas by direct hosing is not recommended, unless necessary for public health and safety.

No
1 Other - Customers
must repair leaks,
breaks, and
malfunctions in a
timely manner
Percentage 0.5% Breaks or leaks are recommended to be corrected within 72 hours of discovery or notice from the City. No
1 Landscape - Other
landscape restriction
or prohibition
Percentage 0.5% Irrigation in manner that allows excessive runoff of water, or unreasonably over-sprays the area of irrigation, is not recommended. No 1 Other - Require
automatic shut of
hoses
Percentage 0.5% Washing cars, boats, trailers or other vehicles and machinery directly with a hose not equipped with a shutoff nozzle is not recommended. No 1 Water Features -
Restrict water use for
decorative water
features, such as
fountains
Percentage 0.5% Use of potable water for non-recycling decorative water fountains is not recommended. No
1 CII - Other CII
restriction or
prohibition
Percentage 0.1%
Use of water for single pass evaporative cooling systems for air conditioning is not recommended for all connections installed after 6 June 2000 unless required for health or safety reasons.

No
1 Other - Prohibit
vehicle washing
except at facilities
using recycled or
recirculating water
Percentage 0.1% Use of water for new, non-recirculating conveyor car wash systems is not recommended. No
Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
8-4 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
How much is this going to
reduce the shortage gap? Additional Explanation or Reference (OPTIONAL)
Penalty, Charge,
or Other
Enforcement? Volume or
Percentage
Shortage Gap
Reduction
Value
1 CII - Other CII
restriction or
prohibition
Percentage 0.1% Use of water for new non-recirculating industrial clothes wash systems is not recommended. No
1 CII - Restaurants may
only serve water
upon request
Percentage 0.1% Restaurants may only serve water upon request. No 1 CII - Lodging
establishment must
offer opt out of linen
service
Percentage 0.1% Hotels and lodging establishments offer a linen service opt-out. No 1 Landscape - Other
landscape restriction
or prohibition
Percentage 1.5% The irrigation with potable water of ornamental turf on public street medians is not recommended. No
1 Landscape - Other
landscape restriction
or prohibition
Percentage 0.1%
Irrigation with potable water outside of newly constructed homes and buildings that is not delivered by drip or microspray systems is not recommended.

No
2 Other Percentage Up to 10% Voluntary action and measures from Stage 1 are now mandatory. Yes 2 Other - Require
automatic shut of
hoses
Percentage 0.5% Use of any garden or utility hose without a hose-end shut-off nozzle is prohibited. Yes
2 Landscape - Limit
landscape irrigation
to specific times
Percentage 1% Irrigation limited to three days per week, and irrigation is limited to the hours between 8pm to 6am. Yes
2 Other - Prohibit use
of potable water for
construction and
dust control
Percentage 0.5% Recycled water must be used for construction dust control. Yes 2 Offer Water Use
Surveys Percentage 1% Conduct water use surveys targeting high water users. Yes Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
8-5 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
How much is this going to
reduce the shortage gap? Additional Explanation or Reference (OPTIONAL)
Penalty, Charge,
or Other
Enforcement? Volume or
Percentage
Shortage Gap
Reduction
Value
2 Other - Prohibit
vehicle washing
except at facilities
using recycled or
recirculating water
Percentage 1% Car washing shall be allowed only at facilities using recycled or recirculating water. Yes
2 Offer Water Use
Surveys Percentage 0.5% Dedicated irrigation customers are required to conduct the irrigation survey.

Yes
3 Other Percentage Up to 20% Continue with action and measures from Stage 2 except where superseded by more stringent requirements. Yes
3 Landscape - Limit
landscape irrigation
to specific days
Percentage 5%
Irrigation limited to two days per week, and irrigation is limited to the hours between 8pm to 6am. This measure is voluntary under Stage 2 and becomes mandatory under Stage 3.

Yes
3 Pools and Spas -
Require covers for
pools and spas
Percentage 0.1% All pools must be covered when not in use. Yes 4 Other Percentage Up to 30% Continue with action and measures from Stage 3 except where superseded by more stringent requirements. Yes
4 Water Features -
Restrict water use for
decorative water
features, such as
fountains
Percentage 0.5% Filling and/or refilling new and existing decorative water features (i.e. ponds, lakes and fountains) is prohibited. Yes
4 Other water feature
or swimming pool
restriction
Percentage 0.5% Filling new swimming pools is prohibited. Yes 4 Other water feature
or swimming pool
restriction
Percentage 0.5% Filling or topping-off of existing swimming pools is prohibited. Yes 4 Offer Water Use
Surveys Percentage 2% Conduct water use surveys targeting high water users. Yes Agenda Item #8.1:

Section 8 2025 Urban Water Management Plan
Water Shortage Contingency Planning City of Sonoma
PUBLIC DRAFT | May 2026
8-6 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
How much is this going to
reduce the shortage gap? Additional Explanation or Reference (OPTIONAL)
Penalty, Charge,
or Other
Enforcement? Volume or
Percentage
Shortage Gap
Reduction
Value
4 Landscape - Limit
landscape irrigation
to specific days
Percentage 15% Irrigation limited to one day per week, and irrigation is limited to the hours between 8pm to 6am. Yes
5 Other Percentage Up to 40% Continue with action and measures from Stage 4 except where superseded by more stringent requirements. Yes
5 Landscape - Prohibit
all landscape
irrigation
Percentage 12% Use of potable water for irrigation is prohibited for all customers. Yes 5 Other Percentage Up to 22%
All residential and Commercial, Industrial, and Institutional (CII) customers shall reach a water reduction of forty five percent (45%) from previous use.

Yes
6 Other Percentage Up to 50% Continue with action and measures from Stage 5 except where superseded by more stringent requirements. Yes
6 Other Percentage (b) No water-using landscape may be installed in new construction. Yes 6 Other Percentage (b) New construction must offset new demand by conserving one times the new demand within the community. Yes
6 Other Percentage (b) No new water-using landscape may be installed by any customer. Yes 6 Other Percentage Up to 34% All residential and CII customers shall reach a water reduction of fifty five percent (55%) from previous use. Yes
NOTES:
(a) Yes, supplier is completing this table using the standard six levels (b) Shortage gap reduction cannot be estimated.

Agenda Item #8.1:

Section 9 2025 Urban Water Management Plan
Demand Management Measures City of Sonoma
PUBLIC DRAFT | May 2026
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9 DEMAND MANAGEMENT MEASURES
 CWC §10631 (e)
Provide a description of the supplier’s water demand management measures. This description shall include all of the following:
(1) (A) For an urban retail water supplier, as defined in Section 10608.12, a narrative description that addresses the nature and extent of each water demand management measure implemented over the past five years. The narrative shall describe the water demand management measures that the supplier plans to implement to achieve its water use targets pursuant to Section 10608.20.
(B) The narrative pursuant to this paragraph shall include descriptions of the following water demand management measures:
(i) Water waste prevention ordinances.
(ii) Metering.
(iii) Conservation pricing.
(iv) Public education and outreach.
(v) Programs to assess and manage distribution system real loss. (vi) Water conservation program coordination and staffing support. (vii) Other demand management measures that have a significant impact on water use as measured in gallons per capita per day, including innovative measures, if implemented.

The goal of the Demand Management Measures (DMM) section in a UWMP is to provide a comprehensive description of the water conservation programs that a supplier has implemented, is currently implementing, and plans to implement in order to meet its urban water use reduction targets. This chapter provides the opportunity for water suppliers to communicate their efforts to promote conservation and to reduce the demand on the water supply.

9.1 Regional Water Conservation
As described in Chapter 2, the SMSWP water suppliers in Sonoma and Marin Counties include the Cities of Santa Rosa, Rohnert Park, Petaluma, Cotati, Cloverdale, and Healdsburg, North Marin Water District, Marin Municipal Water District, Town of Windsor, California American Water – Larkfield District, Sonoma Water, VOMWD, and the City (Partners). The SMSWP was formed in 2010 and its Memorandum of Understanding was amended in May 2018, extending the term by another ten years and adding language to streamline the addition of members to the SMSWP.

Sonoma Water coordinates the work of the SMSWP in conjunction with the Water Advisory Committee (WAC), which provides input to Sonoma Water and holds certain powers and responsibilities enumerated in the Restructured Agreement for Water Supply between Sonoma Water and SMSWP.

Funding
Sonoma Water’s wholesaler water conservation programs are funded by the Partners annually through a WAC recommended budget that allocates a Water Conservation sub-charge for each acre-foot of water sold. The Partners agreed to expend $15 million dollars on water conservation implementation from July 2018 through June 2028. They have also agreed to maintain membership in good standing with the California Water Efficiency Partnership (CalWEP) and implement or use best efforts to secure the implementation of any water conservation requirements added as terms or conditions of Sonoma Water’s appropriative water rights or other regulation or law. Sonoma Water pursues grant funding on behalf of Agenda Item #8.1:

Section 9 2025 Urban Water Management Plan
Demand Management Measures City of Sonoma
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the SMSWP to offset some of the programmatic costs associated with water use efficiency programs and to test new technology.

Annual Report
The Partners are committed to remain as members in good standing of CalWEP and to implement water conservation measures that provide regional benefits and/or that may exceed the targets established from time to time by the Partners or the State. The Partners will implement or use best efforts to secure the implementation of any water conservation requirements and will publish an Annual Report to track progress. The Annual Report will track program implementation, highlight program milestones, and reinforce the importance of protecting and preserving water resources for future generations. The 2024/2025 Annual Report for the SMSWP could be found in the SMSWP’s website. 13 Water and Energy Education Program
The Water and Energy Education Program is a comprehensive approach to helping educators teach students the “value” of water as an important natural resource. Water and energy conservation and stewardship of our local watersheds are promoted throughout the program. Students are encouraged to use water wisely and make environmentally sustainable choices to help secure a reliable source of freshwater now and in the future. The program includes classroom instructional presentations, field study opportunities at Sonoma Water’s Westside Education Facility, free curriculum materials aligned with the existing California State Frameworks and the California Science Standards, a lending library of videos, interactive models and printed materials, production of a newsletter for teachers and endorsement, participation and financial sponsorship of events, assemblies, and workshops. All the education programs and materials are free to teachers in the service area, which covers over 200 schools throughout Sonoma and northern Marin counties.

The total number of students receiving direct instruction in 2024/2025 was 17,392. Students in 2,129 classrooms received school supplies from the program, 21 students participated in the water awareness video contest, 78 classrooms participated in the Steelhead in the Classroom program, and 9,148 students participated in ZunZun Musical Watershed Assemblies.

Public Outreach Program
The SMSWP develops an annual regional outreach campaign that aligns with the region’s current water supply conditions and promotes water use efficiency programs. Sonoma Water, in collaboration with the members of the SMSWP, produces collateral material that aligns with the specific campaign. Sonoma Water coordinates an annual media buy that includes outreach in English and Spanish. Each member of the SMSWP can choose to supplement the campaign with their own media buys. The buys generally include the following:
• Radio (streaming and broadcast),
• Newsprint and online digital media placements in 14 various local publications, • Sonoma County Fair presence,
• Social Media (Facebook, Twitter, Instagram, YouTube, NextDoor), • Mall banners, and
• Movie theater trailers.
13 The 2024-2025 Annual Report for the SMSWP: https://www.savingwaterpartnership.org/wpcontent/uploads/2026/01/SMSWP-Annual-Report-2025-web.pdf Agenda Item #8.1:

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Regional Program
Sonoma Water on behalf of the SMSWP implements numerous regional programs. This includes offering staff support for interested Partners as a cost-effective way to offer local programs to customers of smaller agencies. Some of these programs are:
• High Efficiency Clothes Washer Water Rebate – a rebate for replacing a top-loading clothes washer with a qualifying front-loading clothes washer.
• Green Business Program – Certification for local businesses that are going green. • Qualified Water Efficient Landscaper Training Program – A low-cost professional certification program that educates landscapers about irrigation system auditing, while providing customers with a trusted source for knowledgeable hired help that can save them water. • Eco-Friendly Garden Tour – An annual self-guided garden tour in Sonoma County and North Marin that promotes sustainable landscaping practices.
• Garden Sense – A free garden consultation program open to all Sonoma County residents.

Consultants provide site-specific advice on lawn removal, sprinkler conversion to drip irrigation, and low water use plant selection.
• DIY Energy and Water Savings Toolkit – The Do-It-Yourself (DIY) Home Energy and Water Saving Toolkits are stocked with energy and water saving supplies that can help measure how much energy or water is being consumed in the home and make easy upgrades to your home to help save money on the utility bills.
• Landscape Design Templates – These free, front yard designs are scalable to fit landscaped areas up to 2,500 square feet, ready-to-permit, and in compliance with local Water Efficient Landscape Ordinances.
• Water Smart Plant Label – A free water smart plant labeling program to local nurseries. The water smart plant label highlights low water use plants to nursery customers and promotes sustainable landscaping practices in Sonoma and Marin counties.
• Water-Energy Rebates for Restaurants and Food Service Facilities – a rebate program for replacing inefficient commercial kitchen equipment with new water and energy efficient models.

Sonoma Water participates in numerous regional and statewide initiatives to ensure the SMSWP is on the forefront of water use efficiency, legislation, and conservation planning, such as:
• CalWEP (including presence in the Programs Subcommittee, Research Subcommittee), • California Irrigation Institute,
• Association of California Water Agencies (Water Management and Water Use Efficiency Subcommittees),
• Russian River Watershed Association, and
• California Landscape Contractors Association.

9.2 Agency Water Conservation
 CWC § 10631 (e)
Provide a description of the supplier’s water demand management measures. This description shall include all of the following:
(1) (A) For an urban retail water supplier, as defined in Section 10608.12, a narrative description that addresses the nature and extent of each water demand management measure implemented over the past five years.

Agenda Item #8.1:

Section 9 2025 Urban Water Management Plan
Demand Management Measures City of Sonoma
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The City centrally administers its conservation programs. For purposes of this section, these programs have been grouped in accordance with the DMM categories in CWC §10631(e). These categories are:
(i) Water waste prevention ordinances
(ii) Metering
(iii) Conservation pricing
(iv) Public education and outreach
(v) Programs to assess and manage distribution system real loss (vi) Water conservation program coordination and staffing support, and (vii) Other demand management measures
The following are descriptions of the conservation programs City operates within each of these DMM categories.

9.2.1 DMM 1 – Water Waste Prevention Ordinances
The City prohibits water waste, as detailed in Ordinance 02-2009. The water waste prevention ordinance is in place at all times and is not dependent upon a water shortage for implementation. Additional details could be found in the City’s website:
https://www.codepublishing.com/CA/Sonoma/#!/Sonoma13/Sonoma1310.html#13.10

9.2.2 DMM 2 – Metering
 CWC §526 (a)
Notwithstanding any other provision of law, an urban water supplier that, on or after January 1, 2004, receives water from the federal Central Valley Project under a water service contract or subcontract … shall do both of the following:
(1) On or before January 1, 2013, install water meters on all service connections to residential and nonagricultural commercial buildings constructed prior to January 1, 1992, located within its service area. (2) On and after March 1, 2013, or according to the terms of the Central Valley Project water contract in operation, charge customers for water based on the actual volume of deliveries, as measured by a water meter.  CWC §527 (a)
(a) An urban water supplier that is not subject to Section 526 shall do both of the following:
(1) Install water meters on all municipal and industrial service connections located within its service area on or before January 1, 2025.

The City meters all of its customers in all customer categories, and completed installation of advanced metering infrastructure (AMI) for all meters as of 2025.

9.2.3 DMM 3 – Conservation Pricing
The City has increasing block/tier volumetric water rates for its single-family residential customer class.

Multi-family residential, commercial and dedicated irrigation customer classes have uniform water rates.

The City’s water rate structure was revised in 2023 and is consistent with current law. The City’s current water rates can be found on the City’s website at: https://www.sonomacity.org/water-rates/.

Agenda Item #8.1:

Section 9 2025 Urban Water Management Plan
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9.2.4 DMM 4 – Public Education and Outreach
The City has instituted public education and outreach efforts. Outreach efforts depend on the situation and may include the following:
• Marketing of rebates and giveaways;
• Communicating water use via water bills (e.g., increased frequency of billing, an easy-to-understand bill format, or bills that compare a customer’s water use to the water use of similar customers);
• Providing school education programs;
• Information booths at fairs and public events;
• Newsletters;
• Informative websites, online tools, or social media;
• Newspaper articles; and
• Other activities not listed here.

As described in Section 9.1 above, the City participates in school education outreach administered through the SMSWP. From the 2020-2021 through 2024-2025 school years 2,337 students were reached by direct instruction and nearly 8,300 students were reached through indirect instruction such as assemblies, video and poster contests, and other educational materials.

9.2.5 DMM 5 – Programs to Assess and Manage Distribution System Real Loss The City performs annual water loss audits in accordance with CWC § 10608.34. These audits are prepared using the AWWA Free Water Audit Software, and validated by an AWWA California-Nevada SectionCertified California Water Audit validator prior to submission to DWR. The results of the last five years of water audit data are available through DWR’s Water Use Efficiency Data Portal. 14 The City has an active water loss control program, which include the following programs:
• Large meter accuracy testing,
• Continuous flow notification to customers,
• Zero consumption accounts inspected,
• Timely repair of distribution leaks,
• Systemic replacement of oldest service lines, and
• Transition to self-closing hydrant break plates
In addition, the City contracted Utility Services Associates in 2023 to complete a water leak detection project to assist in identification of areas with leaks that the City should prioritize. 14 DWR’s Water Use Efficiency Data Portal: https://wuedata.water.ca.gov/awwa_plans Agenda Item #8.1:

Section 9 2025 Urban Water Management Plan
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9.2.6 DMM 6 – Water Conservation Program Coordination and Staffing Support The City of Sonoma has an Engineering Technician/Water Conservation Coordinator who works with the City and SMSWP staff to coordinate water conservation activities among twelve member agencies of SMSWP. See Section 9.1 for a summary of the conservation activities implemented by the SMSWP.

Mike Brett
Engineering Technician/Water Conservation Specialist
City of Sonoma
[email protected]
Office: 707-933-2247

9.2.7 DMM 7 – Other Demand Management Measures
For additional DMM information, see the City of Sonoma’s 2025 Water Demand Analysis and Water Conservation Measures Update (Appendix B).

9.3 DMM Implementation Over the Past Five Years
Table 9-1 summarizes program implementation for the last five years. Estimated water savings do not include savings from water waste prevention ordinances, conservation pricing, public information, or distribution system water loss management.

Table 9-1 Implementation of Customer DMMs: 2021-2024
DMM Measures
(Rebate, Direct Install, and Free
Distribution Programs)
2021 – 2025 Total Average Annual
Implementation
High Efficiency Clothes Washer
Rebate Program 9 rebates 2 washer rebates/year
Turf Rebate Program 35,536 square feet 7,100 square feet Estimated Water Savings 4 AFY
NOTES: Data is from the City of Sonoma 2025 Water Demand Analysis and Water Conservation Measure Update, Tables 4-3, 4-4, and 6-2 (included as Appendix B)

9.4 Implementation to Achieve Water Use Targets and Urban Water Use Objectives All the DMMs described above contributed to City’s compliance with the Water Conservation Act of 2009 (SB X7-7) 2020 target GPCD.

In July 2024, California enacted the MCCWL regulation implementing SB 606 and AB 1668 to support longterm water conservation and drought resilience. CWC §10609 requires that urban retail water suppliers report on Urban Water Use Objectives (UWUOs) that are based on specific standards for certain water use sectors. Annual reporting compliance began in January 2025, with UWUO compliance starting in January 2027.

Agenda Item #8.1:

Section 10 2025 Urban Water Management Plan
Plan Adoption, Submittal, and Implementation City of Sonoma PUBLIC DRAFT | May 2026
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10 PLAN ADOPTION, SUBMITTAL, AND IMPLEMENTATION
 CWC §10621 (b)
Every urban water supplier required to prepare a plan pursuant to this part shall, at least 60 days before the public hearing on the plan required by Section 10642, notify any city or county within which the supplier provides water supplies that the urban water supplier will be reviewing the plan and considering amendments or changes to the plan. The urban water supplier may consult with, and obtain comments from, any city or county that receives notice pursuant to this subdivision.

This section provides information on a public hearing, the adoption process for the UWMP and WSCP, the adopted UWMP and WSCP submittal process, plan implementation, and the process for amending the adopted UWMP or WSCP for the City.

10.1 Inclusion of All 2025 Data
This UWMP includes water use and planning data for the entire calendar year of 2025, per the 2025 UWMP Guidebook.

10.2 Notice of Public Hearing
 CWC §10642
Each urban water supplier shall encourage the active involvement of diverse social, cultural, and economic elements of the population within the service area prior to and during the preparation of both the plan and the water shortage contingency plan. Prior to adopting either, the urban water supplier shall make both the plan and the water shortage contingency plan available for public inspection and shall hold a public hearing or hearings thereon. Prior to any of these hearings, notice of the time and place of the hearing shall be published within the jurisdiction of the publicly owned water supplier pursuant to Section 6066 of the Government Code. The urban water supplier shall provide notice of the time and place of a hearing to any city or county within which the supplier provides water supplies.

Notices by a local public agency pursuant to this section shall be provided pursuant to Chapter 17.5 (commencing with Section 7290) of Division 7 of Title 1 of the Government Code. A privately owned water supplier shall provide an equivalent notice within its service area. After the hearing or hearings, the plan or water shortage contingency plan shall be adopted as prepared or as modified after the hearing or hearings.

Prior to adopting the Plan, the City held a public hearing to present information on its UWMP and WSCP on 03 June 2026 at 6:00 PM.

Relevant entities were notified of the UWMP and WSCP review at least 60 days prior to the public hearing, including: (1) cities and counties, and (2) the public. These same entities were noticed again with the specific date, time and location of the hearing at least two weeks prior to the public hearing. The notice to the public, as specified in CGC §6066, and letters to relevant agencies can be found in Appendix C and Appendix D, respectively.

10.2.1 Notice to Cities and Counties
 CWC §10631 (a) A plan shall be adopted in accordance with this chapter that shall do all of the following:

Urban water suppliers shall coordinate with local or regional land use authorities to determine the most appropriate land use information, including, where appropriate, land use information obtained from local or regional land use authorities, as developed pursuant to Article 5 (commencing with Section 65300) of Chapter 3 of Division 1 of Title 7 of the Government Code.

Table 10-1 lists the cities, counties and other entities that were notified. Copies of the notifications are provided in Appendix C.

Agenda Item #8.1:

Section 10 2025 Urban Water Management Plan
Plan Adoption, Submittal, and Implementation City of Sonoma PUBLIC DRAFT | May 2026
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Table 10-1 Notification to Cities and Counties (DWR Table 10-1) City Name 60 Day Notice Notice of Public Hearing
City of Santa Rosa X X
City of Rohnert Park X X
City of Cotati X X
City of Petaluma X X
County Name 60 Day Notice Notice of Public Hearing
County of Sonoma, PRMD X X
Other Entities 60 Day Notice Notice of Public Hearing
Sonoma LAFCO X X
Sonoma County Water Agency X X
Sonoma Valley County Sanitation
District X X
Sonoma Valley Groundwater
Sustainability Agency X X
Marin Municipal Water District X X
North Marin Water District X X
Town of Windsor X X
Valley of the Moon Water District X X

10.2.2 Notice to the Public
Notification to the public and to cities and counties also provided instructions on how to view the UWMP and WSCP prior to the hearing, the revision schedule, and contact information of the UWMP and WSCP preparer. A copy of this notice is included in Appendix D.

Agenda Item #8.1:

Section 10 2025 Urban Water Management Plan
Plan Adoption, Submittal, and Implementation City of Sonoma PUBLIC DRAFT | May 2026
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10.3 Public Hearing and Adoption
 CWC §10608.26
(a) In complying with this part, an urban retail water supplier shall conduct at least one public hearing to accomplish all of the following:
(1) Allow community input regarding the urban retail water supplier’s implementation plan for complying with this part.
(2) Consider the economic impacts of the urban retail water supplier’s implementation plan for complying with this part.
(3) Adopt a method, pursuant to subdivision (b) of Section 10608.20, for determining its urban water use target.  CWC §10621 (b)
Every urban water supplier required to prepare a plan pursuant to this part shall, at least 60 days before the public hearing on the plan required by Section 10642, notify any city or county within which the supplier provides water supplies that the urban water supplier will be reviewing the plan and considering amendments or changes to the plan. The urban water supplier may consult with, and obtain comments from, any city or county that receives notice pursuant to this subdivision.

The deadline for public comments on the UWMP and WSCP was 3 June 2026, the date of the public hearing. The final Plan was formally adopted by the City Council on 3 June 2026, and was submitted to DWR within 30 days of approval. Appendix F presents a copy of the signed Resolution of Plan Adoption.

10.4 Plan Submittal
 CWC §10621 (f)
(1) Each urban water supplier shall update and submit its 2020 plan to the department by July 1, 2026.  CWC §10635 (c)
The urban water supplier shall provide that portion of its urban water management plan prepared pursuant to this article to any city or county within which it provides water supplies no later than 60 days after the submission of its urban water management plan.
 CWC §10644 (a)
(1) An urban water supplier shall submit to the department, the California State Library, and any city or county within which the supplier provides water supplies a copy of its plan no later than 30 days after adoption. Copies of amendments or changes to the plans shall be submitted to the department, the California State Library, and any city or county within which the supplier provides water supplies within 30 days after adoption. (2) The plan, or amendments to the plan, submitted to the department pursuant to paragraph (1) shall be submitted electronically and shall include any standardized forms, tables, or displays specified by the department.

This UWMP and WSCP were submitted to DWR within 30 days of adoption and by the 1 July 2026, deadline. The submittal was done electronically through Water Use Efficiency Data Portal, an online submittal tool. The adopted UWMP and WSCP were also sent to the California State Library and to the cities and counties listed in Table 10-1 no later than 30 days after adoption.

Agenda Item #8.1:

Section 10 2025 Urban Water Management Plan
Plan Adoption, Submittal, and Implementation City of Sonoma PUBLIC DRAFT | May 2026
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10.5 Public Availability
 CWC §10645
(a) Not later than 30 days after filing a copy of its plan with the department, the urban water supplier and the department shall make the plan available for public review during normal business hours. (b) Not later than 30 days after filing a copy of its water shortage contingency plan with the department, the urban water supplier and the department shall make the plan available for public review during normal business hours.

On or about 19 May 2026, an electronic version of the draft UWMP and WSCP were made available for public review by visiting: https://www.sonomacity.org/

10.6 Amending an Adopted UWMP or Water Shortage Contingency Plan  CWC §10644 (b)
If an urban water supplier revises its water shortage contingency plan, the supplier shall submit to the department a copy of its water shortage contingency plan prepared pursuant to subdivision (a) of Section 10632 no later than 30 days after adoption, in accordance with protocols for submission and using electronic reporting tools developed by the department.

If the UWMP or WSCP are amended, each of the steps for notification, public hearing, adoption and submittal will also be followed for the amended document.

Agenda Item #8.1:

Section 11 2025 Urban Water Management Plan
References City of Sonoma
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11 REFERENCES
ABAG, 2021. Plan Bay Area 2050. Association of Bay Area Governments and Metropolitan Transportation Commission, dated October 2021.

ABAG, 2025. Final Regional Housing Needs Allocation (RHNA) Plan: San Francisco Bay Area, 2023-2031, adopted December 2021, updated June 2025.

AWE, 2021. “Water Conservation Tracking Tool - Version 4.0.” Alliance for Water Efficiency (AWE), 2021. https://www.allianceforwaterefficiency.org/resources/tools/waterconservation-tracking-tool.

Cal-Adapt, 2018. Annual Average Maximum Temperature for El Verano, CA. Cal-Adapt website developed by University of California at Berkeley’s Geospatial Innovation Facility under contract with the California Energy Commission. Retrieved 15 March 2026, from https://v2.caladapt.org/tools/local-climate-change-snapshot/.

California Department of Water Resources (DWR), 2026. Urban Water Management Plan Guidebook. https://water.ca.gov/-/media/DWR-Website/Web-Pages/Programs/Water-Use-AndEfficiency/Urban-Water-Use-Efficiency/Urban-Water-Management-Plans/Final-2025-UWMPGuidebook/Final-2025-UWMP-Guidebook-Accessible.pdf City of Sonoma, 2006. 2020 General Plan. https://www.sonomacity.org/general-plan/.

DOF, 2024. E-4 Population Estimates for Cities, Counties, and the State, 2021-2024, with 2020 Census Bookmark. State of California, Department of Finance (DOF), May 2024.

EKI, 2025. 2025 Water Demand Analysis and Water Conservation Measure Update, prepared for the City of Sonoma on December 2025.

Sonoma County, 2020. Sonoma County General Plan 2020, Land Use Element. https://permitsonoma.org/Microsites/Permit%20Sonoma/Documents/Long%20Range%20Plans/ Land-Use-Element-REVISED.pdf.

Sonoma County, 2021. Sonoma County Multi-Jurisdictional Hazard Mitigation Plan Update 2021. https://permitsonoma.org/Microsites/Permit%20Sonoma/Documents/Divisions/Planning/Long %20Range%20Plans/Hazard%20Mitigation%20Plan/Adopted-Sonoma-County-MJHMP-Volume1-December-2021.pdf Sonoma Water, 2024. Sonoma County Water Agency Local Hazard Mitigation Plan, dated 19 September 2024.

Sonoma Water, 2025. 2025 Russian River Biological Opinion. Presentation slides presented to the Lower River Municipal Advisory Committee on 11 September 2025. https://sonomacounty.gov/Main%20County%20Site/Administrative%20Support%20%26%20Fisc al%20Services/BoS/BCCs/Documents/Lower%20Russian%20River%20Municipal%20Advisory/20 25/Sept/SonomaWater-slides-Sept2025.pdf
Sonoma Water, 2026. Draft 2025 Urban Water Management Plan, prepared by Brown and Caldwell, April 2026.

Agenda Item #8.1:

Section 11 2025 Urban Water Management Plan
References City of Sonoma
PUBLIC DRAFT | May 2026
11-2 EKI Environment & Water, Inc.

Sonoma Valley GSA, 2021. Groundwater Sustainability Plan Sonoma Valley Groundwater Subbasin.

Prepared by Sonoma Water. https://sonomavalleygroundwater.org/gsp/.

U.S. Census Bureau, 2026. U.S. Census Bureau QuickFacts for Sonoma County, accessed on 07 March 2026, https://www.census.gov/quickfacts/.

Agenda Item #8.1:

Appendix A: Completed UWMP Checklist
Agenda Item #8.1:

City of Sonoma
2025 UWMPChecklist
Retail
(x = required)
Wholesale
(x = required) Order 2025 Guidebook Location Water Code Section Summary as Applies to UWMP Subject Relevant Submittal Table 2025 UWMP Location x x 1 Chapter 1 10615 A plan shall describe and evaluate sources of supply, reasonable and practical efficient uses, reclamation and demand management activities. Introduction and overview n/a Pg. 1-1 x x 1 Chapter 1 10630.5
Each plan shall include a simple description of the Supplier’s plan including water availability, future requirements, a strategy for meeting needs, and other pertinent information. Additionally, a Supplier may also choose to include a simple description at the beginning of each chapter.

Plan preparation n/a Executive Summary (pg. ES-1)
x x 2.1 Section 2.1 10620(b) Every person that becomes a Supplier shall adopt UWMP within one year after it has become a Supplier. Plan preparation n/a Pg. 2-1 x n/a 2.5 Section 2.5 10644 Supplier shall report the Public Water Systems number, volume of delivered water, and number of connections that are included in this UWMP. Plan preparation 2-1 Pg. 2-2 x x 2.5 Section 2.5 10644 Supplier shall report if this UWMP is an individual UWMP and whether the Supplier belongs to a regional UWMP or regional alliance. Plan preparation 2-2 Pg. 2-2 x x 2.5 Section 2.5 10644 Supplier shall report whether the data is in fiscal or calendar years and the units of measure used for reporting water volumes. Plan preparation 2-3 Pg. 2-3 - 2-5, Appendices C and D x x 2.4 Section 2.4 10642
Provide supporting documentation that the Supplier has encouraged activeinvolvement of diverse social, cultural, and economic elements of the population within the service area prior to and during the preparation of the plan and contingency plan.

Plan preparation n/a Pg. 2-4
x x 2.4 Section 2.4.2 10620(d)(3)
Coordinate the preparation of its plan with other appropriate agencies in the area, including other Suppliers that share a common source, water management agencies, and relevant public agencies, to the extent practicable.

Plan preparation n/a Pg. 2-3 - 2-5, Appendices C and D
x n/a 2.4 Section 2.4.1 10631(h) Retail Suppliers will include documentation that they have provided their Wholesale Supplier(s)—if any—with water use projections from that source. Plan preparation 2-4 R Pg. 2-3 - 2-4 x x 3 Chapter 3.0 10631(a) Describe the Supplier service area. System description n/a Pg. 3-1 - 3-2 x x 3.3 Section 3.3 10631(a) Describe the climate of the Supplier’s service area. System description n/a Pg. 3-3 - 3-5 x x 3.4 Section 3.4.1 10631(a) Provide the current and projected service area populations for 2030, 2035, 2040, 2045 and optionally 2050. System description 3-1 Pg. 3-5 - 3-6 x x 3.4 Section 3.4.2 10631(a) Describe other social, economic, and demographic factors affecting the Supplier’s water management planning. System description n/a Pg. 3-6 - 3-7 x x 3.5 Section 3.5 10631(a)
Describe the land uses within the service area… include the current andprojected land uses within the existing or anticipated service area affecting the Supplier’s water management planning. Describe the land uses within the service area.

System description and
baselines n/a Pg. 3-8 - 3-9
x Optional 4.2 Sections 4.2.3 and 4.2.4 10631(d)(1) Quantify past, current, and projected water use, identifying the uses among water use sectors. System water use 4-1 and 4-2 Pg. 4-1 - 4-10 x Optional 4.3 Section 4.3.1 10631(d)(3)(A) Report the distribution system water loss for each of the five years preceding the plan update. System water use 4-5 Pg. 4-5 - 4-6 x n/a 4.3 Section 4.3.2 10631(d)(3)(C) Retail Suppliers shall provide data to show the distribution loss standards were met. System water use 4-6 Pg. 4-6 - 4-7 x n/a 4.2 Section 4.2.5.4 10631.1(a) Include projected water use needed for lower income housing projected in the service area of the Supplier. System water use 4-3 Pg. 4-11 x n/a 4.2 Section 4.2.5.3 10631(d)(4)(A) In projected water use, include estimates of water savings from adopted codes, plans, and other policies or laws. System water use 4-3 Pg. 4-8 - 4-9 x n/a 4.2 Section 4.2.5.3 10631(d)(4)(B) Provide citations of codes, standards, ordinances, or plans used to make water use projections. System water use 4-3 Appendix B x n/a 4.2 Section 4.2.5.3 10631(d)(4)(B)(ii)
To the extent that a Supplier reports the information described in subparagraph (A), an urban water Supplier shall… Indicate the extent that the water use projections consider savings from codes, standards, ordinances, or transportation and land use plans. Water use projections that do not account for these water savings shall be noted of that fact
System water use 4-3 Pg. 4-10
x x 4.2 Section 4.2.5.6 10635(b) Demands under climate change considerations must be included as part of the drought risk assessment. System water use n/a Pg. 4-12 x n/a 5.2 Section 5.2 10608.4
Retail Suppliers shall report on their compliance in meeting their water use targets. Reporting requirements will vary depending on whether the Supplier:- Was considered an urban retail water supplier in 2020,- Met its 2020 target in 2020, or- Was part of a merger or consolidation since 2020.Chapter 5 Subsections 5.2.1, 5.2.2, and 5.2.3 address each of these situations.

Baselines and targets 5-1 Pg. 5-1 - 5-2
x x 6.1 Section 6.1 10631(b)(2) When multiple sources of water supply are identified, describe the management of each supply in relationship to other identified supplies. System supplies n/a Pg. 6-20 - 6-22 x x 6.1 Sections 6.1 and 6.2 10631(b)(1)
Provide a discussion of anticipated supply availability under a normal, single dry year, and a drought lasting five years, as well as more frequent and severe periods of drought, including changes in supply due to climate change.

System supplies n/a Pg. 7-29 - 7-32
x x 6.2 Section 6.2.2 10631(b)(4)(C)
Indicate whether groundwater is an existing or planned source of water available to the Supplier. If groundwater is identified as an existing or planned source of water… (include) a detailed description and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past five years
Water supplies and recycled
water 6-1 Pg. 6-4 - 6-10
x x 6.2 Section 6.2.2 10631(b)(4)(A)
Indicate whether a groundwater sustainability plan or groundwater management plan has been adopted by the Supplier or if there is any other specific authorization for groundwater management. Include a copy of the plan or authorization.

System supplies n/a Pg. 6-7 - 6-9
x x 6.2 Section 6.2.2 10631(b)(4)(B) Describe the groundwater basin. System supplies n/a Pg. 6-4 - 6-10 x x 6.2 Section 6.2.2 10631(b)(4)(B)
Indicate if the basin has been adjudicated and include a copy of the court order or decree and a description of the amount of water the Supplier has the legal right to pump.

System supplies n/a Pg. 6-4 - 6-10
Agenda Item #8.1:

City of Sonoma
2025 UWMPChecklist
Retail
(x = required)
Wholesale
(x = required) Order 2025 Guidebook Location Water Code Section Summary as Applies to UWMP Subject Relevant Submittal Table 2025 UWMP Location x x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… (include) information as to whether DWR has identified the basin as a high- or medium-priority basin in the most current official departmental bulletin…
Water supplies and recycled
water n/a Pg. 6-4 - 6-10
x x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… describe efforts by the Supplier to coordinate with sustainability or groundwater agencies to achieve sustainable groundwater conditions.

Water supplies and recycled
water n/a Pg. 6-4 - 6-10
x x 6.2 Section 6.2.2. 10631(b)(4)(C)
If groundwater is identified as an existing or planned source of water… (include) a detailed description and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past five years.

System supplies n/a Pg. 6-4 - 6-10
x x 6.2 Section 6.2.2 10631(b)(4)(D) Provide a detailed description and analysis of the amount and location of groundwater that is projected to be pumped. System supplies 6-9 Pg. 6-20 - 6-21 x x 6.1 Section 6.1 10631(b) Identify and quantify the existing and planned sources of water available for 2025, 2030, 2035, 2040, 2045 and optionally 2050. System supplies 6-8 and 6-9 Pg. 6-20 - 6-21, Pg. 7-27 - 7-28, Pg. 7-31
x x 6.2 Section 6.2.7 10631(c) Describe the opportunities for exchanges or transfers of water on a short-term or long-term basis. System supplies n/a Pg. 6-17 x n/a 6.2 Section 6.2.5 10633(a)
Describe the wastewater collection and treatment systems in the Supplier’s service area with quantified amount of collection and treatment and the disposal methods.

System supplies (recycled water) 6-2 Pg. 6-10 - 6-13
x x 6.2 Section 6.2.5 10633(b)
Describe the quantity of treated wastewater that meets recycled water standards, is being discharged, and is otherwise available for use in a recycled water project.

System supplies (recycled water) 6-3 Pg. 6-10 - 6-13
x x 6.2 Section 6.2.5 10633(c) Describe the recycled water currently being used in the Supplier's service area. System supplies (recycled water) 6-4 Pg. 6-14 - 6-16 x x 6.2 Section 6.2.5 10633(d) Describe and quantify the potential uses of recycled water and provide a determination of the technical and economic feasibility of those uses. System supplies (recycled water) 6-4 Pg. 6-15 - 6-16 x x 6.2 Section 6.2.5 10633(e)
Describe the projected use of recycled water within the Supplier's service area at the end of 5, 10, 15, and 20 years, and describe the actual use of recycled water in comparison to uses previously projected.

System supplies (recycled water) 6-4 and 6-5 Pg. 6-15 - 6-16 x x 6.2 Section 6.2.5 10633(f)
Describe the actions that may be taken to encourage the use of recycled water and the projected results of these actions in terms of acre-feet of recycled water used per year.

System supplies (recycled water) 6-6 Pg. 6-14 - 6-15
x x 6.2 Section 6.2.5 10633(g) Provide a plan for optimizing the use of recycled water in the Supplier's service area. System supplies (recycled water) n/a Pg. 6-15 - 6-16 x x 6.2 Section 6.2.6 10631(g) Describe desalinated water project opportunities for long-term supply. System supplies 6-7 Pg. 6-17 x x 6.2 Section 6.2.10 10631(f)
Describe the expected future water supply projects and programs that may be undertaken by the water Supplier to address water supply reliability in average, single-dry, and for a period of drought lasting five consecutive water years.

System supplies 6-7 Pg. 6-17 to 6-20
x x 6.3 Section 6.3 and Appendix O 10631.2(a) The UWMP must include energy information, as stated in the code, that a Supplier can readily obtain.

System suppliers, energy
intensity
O-1A, O-1B, O-1C,
and O-2 Pg. 6-23 to 6-24
x 7.1 Section 7.1 10634
Provide information on the quality of existing sources of water available to the Supplier and the manner in which water quality affects water management strategies and supply reliability.

Water supply reliability
assessment n/a Pg. 7-4 to 7-5
x x 7.2 Section 7.2 10635(a)
Service Reliability Assessment: Assess the water supply reliability during normal, dry, and a drought lasting five consecutive water years by comparing the total water supply sources available to the Supplier with the total projected water use over the next 20 years.

Water supply reliability
assessment 7-2, 7-3, and 7-4 Pg. 7-8 to 7-10
x x 7.2 Section 7.2.3 10620(f) Describe water management tools and options to maximize resources and minimize the need to import water from other regions. Water supply reliability assessment n/a Pg. 7-11 x x 7.3 Section 7.3 10635(b) Provide a drought risk assessment as part of information considered in developing the demand management measures and water supply projects. Water supply reliability assessment n/a Pg. 7-11 to 7-12 x x 7.3 Section 7.3 10635(b)(1)
Include a description of the data, methodology, and basis for one or more supply shortage conditions that are necessary to conduct a drought risk assessment for a drought period that lasts five consecutive years.

Water supply reliability
assessment n/a Pg. Pg. 7-11
x x 7.3 Section 7.3 10635(b)(2) Include a determination of the reliability of each source of supply under a variety of water shortage conditions. Water supply reliability assessment n/a Pg. 7-12 x x 7.3 Section 7.3 10635(b)(3) Include a comparison of the total water supply sources available to the Supplier with the total projected water use for the drought period. Water supply reliability assessment 7-5 Pg. 7-12x x 7.3 Section 7.3 10635(b)(4) Include considerations of the historical drought hydrology, plausible changes on projected supplies and demands under climate change conditions, anticipated regulatory changes, and other locally applicable criteria.

Water supply reliability
assessment n/a Pg. 7-11 - 7-12
x x 8 Chapter 8 10632(a) Provide a water shortage contingency plan (WSCP) with specified elements below. Water shortage contingency planning n/a Appendix E
x x 8 Chapter 8 10632(a)(1) Provide an analysis of water supply reliability (from Guidebook Chapter 7) in the WSCP. Water shortage contingency planning n/a Appendix E
x x 8.2 Section 8.2 10632(a)(2)(A) Provide the written decision-making process and other methods that the Supplier will use each year to determine its water reliability. Water shortage contingency planning n/a Appendix E
x x 8.2 Section 8.2 10632(a)(2)(B) Provide data and methodology to evaluate the Supplier’s water reliability for the current year and one dry year pursuant to factors in the code. Water shortage contingency planning n/a Appendix E
x x 8.3 Section 8.3 10632(a)(3)(A)
Define six standard water shortage levels of 10%, 20%, 30%, 40%, 50% shortage, and greater than 50% shortage. These levels shall be based on supply conditions, including percent reductions in supply, changes in groundwater levels, changes in surface elevation, or other conditions. The shortage levels shall also apply to a catastrophic interruption of supply Water shortage contingency
planning n/a Appendix E
x x 8.3 Section 8.3 10632(a)(3)(B) Suppliers with an existing WSCP that uses different water shortage levels must cross reference their categories with the six standard categories. Water shortage contingency planning 8-1 Appendix E
x x 8.4 Section 8.4 10632(a)(4)(A) Suppliers with WSCPs that align with the defined shortage levels must specify locally appropriate supply augmentation actions. Water shortage contingency planning 8-2 Appendix E
x x 8.4 Section 8.4 10632(a)(4)(B) Specify locally appropriate demand reduction actions to adequately respond to shortages. Water shortage contingency planning 8-3 Appendix E
x x 8.4 Section 8.4 10632(a)(4)(C) Specify locally appropriate operational changes. Water shortage contingency planning 8-2 Appendix E
Agenda Item #8.1:

City of Sonoma
2025 UWMPChecklist
Retail
(x = required)
Wholesale
(x = required) Order 2025 Guidebook Location Water Code Section Summary as Applies to UWMP Subject Relevant Submittal Table 2025 UWMP Location x x 8.4 Section 8.4 10632(a)(4)(D)
Specify additional mandatory prohibitions against specific water use practices that are in addition to State-mandated prohibitions are appropriate to local conditions.

Water shortage contingency
planning Table 8-3 Appendix E
x x 8.4 Section 8.4 10632(a)(4)(E) Estimate the extent to which the gap between supplies and demand will be reduced by implementation of the action. Water shortage contingency planning 8-2 and 8-3 Appendix E
x x 8.4 Section 8.4.6 10632.5 The UWMP shall include a seismic risk assessment and mitigation plan. Water shortage contingency plan n/a Appendix E x x 8.5 Section 8.5 10632(a)(5)(A) Suppliers must describe that they will inform customers, the public and others regarding any current or predicted water shortages. Water shortage contingency planning n/a Appendix E
x x 8.5 Section 8.5 10632(a)(5)(B), 10632(a)(5)(C) Suppliers must describe that they will inform customers, the public and others regarding any shortage response actions triggered or anticipated to be triggered and other relevant communications. Water shortage contingency planning n/a Appendix E x n/a 8.6 Section 8.6 10632(a)(6) Retail Supplier must describe how it will ensure compliance with and enforce provisions of the WSCP.

Water shortage contingency
planning n/a Appendix E
x x 8.7 Section 8.7 10632(a)(7)(A) Describe the legal authority that empowers the Supplier to enforce shortage response actions. Water shortage contingency planning n/a Appendix E
x x 8.7 Section 8.7 10632(a)(7)(B) Provide a statement that the Supplier will declare a water shortage emergency per Water Code Chapter 3. Water Shortage Emergencies .

Water shortage contingency
planning n/a Appendix E
x x 8.7 Section 8.7 10632(a)(7)(C)
Provide a statement that the Supplier will coordinate with any city or county within which it provides water for the possible proclamation of a local emergency.

Water shortage contingency
planning n/a Appendix E
x x 8.8 Section 8.8 10632(a)(8)(A) Describe the potential revenue reductions and expense increases associated with activated shortage response actions. Water shortage contingency planning n/a Appendix E
x x 8.8 Section 8.8 10632(a)(8)(B)
Provide a description of mitigation actions needed to address revenue reductions and expense increases associated with activated shortage response actions.

Water shortage contingency
planning n/a Appendix E
x n/a 8.8 Section 8.8 10632(a)(8)(C) Retail Suppliers must describe the cost of compliance with Water Code Chapter 3.3, Excessive Residential Water Use During Drought . Water shortage contingency planning n/a Appendix E
x n/a 8.9 Section 8.9 10632(a)(9)
Retail Suppliers must describe the monitoring and reporting requirements and procedures that ensure appropriate data are collected, tracked, and analyzed for purposes of monitoring customer compliance.

Water shortage contingency
planning n/a Appendix E
x x 8.10 Section 8.10 10632(a)(10)
Describe reevaluation and improvement procedures for monitoring and evaluation the WSCP to ensure risk tolerance is adequate and appropriate water shortage mitigation strategies are implemented.

Water shortage contingency
planning n/a Appendix E
x n/a 8.11 Section 8.11 10632(b)
Analyze and define water features that are artificially supplied with water, including ponds, lakes, waterfalls, and fountains, separately from swimming pools and spas.

Water shortage contingency
planning n/a Appendix E
x x 8.12 Section 8.12 10632(c) Make available the WSCP to customers and any city or county where it provides water within 30 days after adoption of the plan.

Water shortage contingency
planning n/a Appendix E
x n/a 9.1 Sections 9.1 10631(e)(1)
Retail Suppliers shall provide a description of the nature and extent of each demand management measure implemented over the past five years. The description will address specific measures listed in code.

Demand management measures n/a Pg. 9-6
x n/a 10 Chapter 10 10608.26(a)
Retail Suppliers shall conduct a public hearing to discuss adoption, implementation, and economic impact of water use targets (recommended to discuss compliance).

Plan adoption, submittal, and
implementation n/a Pg. 10-3
x x 10.2 Section 10.2.1 10621(b)
Notify, at least 60 days prior to the public hearing, any city or county within which the Supplier provides water that the Supplier will be reviewing the UWMP and considering amendments or changes to the plan.

Plan adoption, submittal, and
implementation 10-1 Pg. 10-2
x x 10.4 Section 10.4 10621(f) Each urban water Supplier shall update and submit its 2025 plan to DWR by July 1, 2026. Plan adoption, submittal, and implementation n/a Pg. 10-3 x x 10.2 Sections 10.2.2, 10.3, and 10.5 10642 Provide supporting documentation that the Supplier made the UWMP and WSCP available for public inspection, published notice of the public hearing, and held a public hearing about the UWMP and WSCP. Plan adoption, submittal, and implementation n/a Pg. 10-1 - 10-3, Appendices C and D
x x 10.2 Section 10.2.2 10642 The Supplier is to provide the time and place of the hearing to any city or county within which the Supplier provides water. Plan adoption, submittal, and implementation 10-1 Pg. 10-1 - 10-2, Appendix D x x 10.3 Section 10.3.2 10642 Provide supporting documentation that the UWMP and WSCP has been adopted as prepared or modified.

Plan adoption, submittal, and
implementation n/a Appendix F
x x 10.4 Section 10.4 10644(a) Provide supporting documentation that the Supplier has submitted their UWMP to the California State Library. Plan adoption, submittal, and implementation n/a Appendix Fx x 10.4 Section 10.4 10644(a)(1) Provide supporting documentation that the Supplier has submitted their UWMP to any city or county within which the Supplier provides water no later than 30 days after adoption.

Plan adoption, submittal, and
implementation n/a Appendix D
x x 10.4 Sections 10.4.1 and 10.4.2 10644(a)(2) The UWMP, or amendments to the UWMP, submitted to DWR shall be submitted electronically. Plan adoption, submittal, and implementation n/a Pg. 10-3 to 10-4 x x 10.7 Section 10.7.2 10644(b) If revised, submit a copy of the WSCP to DWR within 30 days of adoption. Plan adoption, submittal, and implementation n/a Pg. 10-4 x x 10.5 Section 10.5 10645(a)
Provide supporting documentation that, not later than 30 days after filing a copy of its UWMP with DWR, the Supplier has or will make the plan available for public review during normal business hours.

Plan adoption, submittal, and
implementation n/a Pg. 10-4
x x 10.5 Section 10.5 10645(b)
Provide supporting documentation that, not later than 30 days after filing a copy of its WSCP with DWR, the Supplier has or will make the plan available for public review during normal business hours.

Plan adoption, submittal, and
implementation n/a Pg. 10-4
x x 10.6 Section 10.6 10621(c) If Supplier is regulated by the Public Utilities Commission, include its plan and contingency plan as part of its general rate case filings. Plan adoption, submittal, and implementation n/a Not applicable Agenda Item #8.1:

Appendix B: 2025 Urban Water Management Plan
Water Demand Analysis and Water Conservation
Measures Update
Agenda Item #8.1:

EKI A80038.00 i 22 December 2025
2025 WATER DEMAND ANALYSIS

AND WATER CONSERVATION

MEASURE UPDATE
City of Sonoma
22 December 2025
EKI C40180.00
EKI ENVIRONMENT & WATER, INC. www.ekiconsult.com
2001 Junipero Serra Blvd, Suite 300 • Daly City, CA 94014 Agenda Item #8.1:

2025 WATER DEMAND ANALYSIS AND WATER CONSERVATION

MEASURE UPDATE
22 December 2025
Prepared for:

City of Sonoma
Prepared by:

EKI Environment & Water, Inc.
2001 Junipero Serra Blvd., Suite 300
Daly City, California 94014
(650) 292-9100
www.ekiconsult.com
EKI C40180.00
Agenda Item #8.1:

22 December 2025
i EKI C40180.00
2025 Water Demand Analysis and Water Conservation
Measure Update
City of Sonoma

TABLE OF CONTENTS
1 INTRODUCTION....................................................................................................... 1-1 2 REGULATORY CONTEXT ........................................................................................... 2-1

2.1 UWMP Demand Projections Requirements.......................................................... 2-1

2.2 New Requirements for Water Use Efficiency........................................................ 2-2

2.2.1 Making Conservation a California Way of Life ................................................... 2-2

2.2.2 Related Regulations with MCCWL Compliance Implications............................. 2-4 3 WATER USE CHARACTERISTICS ................................................................................ 3-1

3.1 Historical Total and Per Capita Water Use............................................................ 3-1

3.2 Water Use Trends by Customer Sector................................................................. 3-6

3.3 Estimated Indoor and Outdoor Water Use ........................................................... 3-9 4 CONSERVATION PROGRAM PARTICIPATION ............................................................ 4-1

4.1 Conservation Programs........................................................................................ 4-1

4.2 Historical Conservation Program Participation ..................................................... 4-2

4.3 Estimated Savings from Past Conservation Programs ........................................... 4-2 5 WATER DEMAND PROJECTIONS............................................................................... 5-1

5.1 Basis for Account Growth Projections.................................................................. 5-1

5.2 Planned Development Within the Service Area.................................................... 5-5

5.3 Water Demand Factors........................................................................................ 5-5

5.3.1 Potable Water..................................................................................................... 5-5

5.3.2 Non-Revenue Water and Water Loss................................................................. 5-6

5.4 Passive Water Savings Estimate ........................................................................... 5-6

5.5 Projected Water Demand Through 2050 .............................................................. 5-7

5.6 Projected Compliance with UWUOs................................................................... 5-10 6 CONSERVATION MEASURES UPDATE ....................................................................... 6-1

6.1 Methodology for Screening of Potential Water Conservation Measures............... 6-1

6.2 Screening of Conservation Measures for Regional Implementation ...................... 6-2

6.2.1 Public Outreach and Education-Based Conservation Programs........................ 6-2

6.2.2 Device and Financial Incentive-Based Conservation Programs ......................... 6-2

6.2.3 Regional Program Screening Findings................................................................ 6-4 Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma
22 December 2025
ii EKI C40180.00

6.3 Screening of Conservation Measures for Local Implementation............................ 6-4

6.3.1 Agency Actions and Water Rate Conservation Programs.................................. 6-4

6.3.2 Public Outreach and Education Based Conservation Programs......................... 6-4

6.3.3 Device and Financial Incentive Based Conservation Programs.......................... 6-4

6.3.4 Policy and Regulation Based Conservation Programs........................................ 6-4

6.4 Evaluation of Future Water Conservation Programs............................................. 6-5 7 CONCLUSIONS......................................................................................................... 7-1

7.1 Historical, Current, and Projected Water Demand................................................ 7-1

7.2 Conservation Measures Participation, Savings, and Update.................................. 7-1 8 REFERENCES............................................................................................................ 8-1

TABLES (IN REPORT TEXT)
Table 3-1 Total and Per-Capita Water Use......................................................................... 3-2 Table 3-2 Annual Water Use by Customer Sector.............................................................. 3-4 Table 3-3 Average Per Account Water Use by Sector Group............................................. 3-8 Table 4-1 Description of Conservation Programs .............................................................. 4-1 Table 4-2 Participation in SMSWP School Education Programs, Direct Instruction .......... 4-2 Table 4-3 Summary of Conservation Program Participation.............................................. 4-4 Table 4-4 Estimated Water Savings Achieved by Conservation Programs and Passive Savings............................................................................................4-6 Table 5-1 Historical and Projected Account Growth Rate by Customer Sector................. 5-2 Table 5-2 Population and Employment Projections........................................................... 5-3 Table 5-3 Selected Water Demand Factors........................................................................ 5-5 Table 5-4 Projected Demand and Passive Conservation.................................................... 5-7 Table 5-5 Projected Water Demand by Sector................................................................... 5-8 Table 5-6 Actual and Projected Water Use vs. Urban Water Use Objectives.................. 5-11 Table 6-1 Prioritization of Conservation Measures and Programs, Regional Rankings..... 6-3 Table 6-2 Conservation Measure Scenarios....................................................................... 6-7 Table 6-3 Costs and Savings of Potential Conservation Programs..................................... 6-8 Table 6-4 Program Scenario Total Conservation Savings and Unit Costs.......................... 6-9 Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma
22 December 2025
iii EKI C40180.00

FIGURES (IN REPORT TEXT)
Figure 1-1 Participating Sonoma-Marin Saving Water Partnership Members.................... 1-3 Figure 1-2 City of Sonoma Service Area .............................................................................. 1-4 Figure 2-1 Components of Urban Water Use Objective...................................................... 2-2 Figure 2-2 Progression of Objectives Indoor and Outdoor Efficiency Standards Through 2040................................................................................................................. 2-5 Figure 2-3 General Timeline of MCCWL Regulatory Requirements.................................... 2-6 Figure 3-1 Total Water Production and Per-Capita Water Use........................................... 3-3 Figure 3-2 Annual Water Use by Sector Group ................................................................... 3-5 Figure 3-3 Proportional Water Use by Sector Group in 2024 ............................................. 3-5 Figure 3-4 Monthly Water Use and 12-Month Moving Average ........................................ 3-7 Figure 3-5 Average Per-Account Water Use by Sector Group............................................. 3-9 Figure 3-6 Average Monthly Water Use, 2010-2024......................................................... 3-10 Figure 3-7 Estimated Indoor and Outdoor Water Use, 2024 ............................................ 3-11 Figure 4-1 Conservation Program Participation by Program Type...................................... 4-5 Figure 4-2 Estimated Water Savings Achieved by Conservation Programs........................ 4-7 Figure 5-1 Population and Employment Projections........................................................... 5-4 Figure 5-2 Water Demand Projections................................................................................ 5-9 Figure 5-3 Actual and Projected Water Use vs. Urban Water Use Objectives.................. 5-11 Figure 5-4 Projected Water Use vs. Urban Water Use Objectives by Component........... 5-12 Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma
22 December 2025
iv EKI C40180.00

APPENDICES
Appendix A Methodology for Estimating Indoor and Outdoor Water Use Appendix B Conservation Program Assumptions
Appendix C Prioritization and Screening of Future Water Conservation Measures

ABBREVIATIONS AND ACRONYMS
AB Assembly Bill
AFY acre-feet per year
AMI advanced metering infrastructure
AWE Alliance for Water Efficiency
BMPs Best Management Practices
CII Commercial, Industrial, and Institutional
City City of Sonoma
CWC California Water Code
DIM dedicated irrigation meter
DMM demand management measure
DWR Department of Water Resources
GPCD gallons per capita per day
gpf gallons per flush
HECW high-efficiency clothes washer
HET high-efficiency toilet
LEF landscape efficiency factors
MCCWL Making Conservation a California Way of Life
MFR multi-family residential
MUMs mixed-use meters
Objective Urban Water Use Objective
QWEL Qualified Water Efficient Landscaper
Report Water Demand and Conservation Report
SB Senate Bill
SFR single-family residential
SMSWP Sonoma-Marin Saving Water Partnership
State Water Board State Water Resources Control Board
TM technical memorandum
UWMP Urban Water Management Plan
Water Contractors The nine members of the SMWSP participating in this project.

Agenda Item #8.1:

Section 1 2025 Demand & Conservation Update
Introduction City of Sonoma
22 December 2025
1-1 EKI C40180.00
1 INTRODUCTION
To support the development of the 2025 Urban Water Management Plan (UWMP) updates, nine members of the Sonoma-Marin Saving Water Partnership (SMSWP) coordinated to conduct a joint update of their water demand projections and water conservation planning efforts (i.e., the 2025 Water Demand and Conservation Project). The participating SMSWP members include the City of Cotati, City of Petaluma, City of Rohnert Park, City of Santa Rosa, City of Sonoma, Marin Municipal Water District, North Marin Water District, Town of Windsor, and Valley of the Moon Water District. These nine participating SMSWP members (referred to as Water Contractors herein) are shown on Figure 1-1.

The goals of the 2025 Water Demand and Conservation Project are to apply a common methodology to conduct the following analysis for each Water Contractor:
• Evaluate and document recent historical water use characteristics and trends, including population and account growth (in this report, the term “account” indicates “water connection”);
• Estimate projected water demands for the years 2030 through 2050 to support both the 2025 UWMP update and coordination and planning efforts with Sonoma Water; • Update the suite of common regional conservation measures that are being considered for implementation in the future;
• Review and document past participation in water conservation programs; and • Estimate the potential water savings associated with future water conservation program implementation.

This 2025 Water Demand and Conservation Measure Update presents the results for the City of Sonoma(City), located in Sonoma County, and serving a population of approximately 11,487 people in 2024 (Figure 1-2). The City’s water supplies include surface water purchased from Sonoma Water, supplemental local groundwater supply, and recycled water produced by the Sonoma Valley County Sanitation District (EKI, 2021). Conservation has been achieved through the implementation of water conservation programs, including most administered by the regional SMSWP and some administered through the City.

This 2025 Water Demand and Conservation Report is organized as follows:
• Section 1 identifies the goals and objectives of the Report; • Section 2 provides the regulatory context for the demand projections as described in the Report as well as new requirements related to Making Conservation a California Way of Life (MCCWL; Assembly Bill [AB]-1668/ Senate Bill [SB]-606) that impact the water demand and conservation planning components of the 2025 UWMPs; • Section 3 describes historical water use patterns and characteristics within the City; • Section 4 documents past participation in conservation programs and estimated savings associated with program implementation, and presents the results of a detailed analysis of program participation trends for select conservation programs; Agenda Item #8.1:

Section 1 2025 Demand & Conservation Update
Introduction City of Sonoma
22 December 2025
1-2 EKI C40180.00
• Section 5 describes the projected water demands through 2050, including the assumptions and methodology used;
• Section 6 documents the water conservation measure screening process, identifies individual programs and program scenarios for potential future implementation by the City;
• Section 7 documents the key findings and conclusions from the analyses presented throughout this report; and
• Section 8 provides key references and sources.

Agenda Item #8.1:

Path: X:\C40180\Map\_.00\2025\09\ReportFigures.aprx
Notes

1. All locations are approximate.

Sonoma Marin Saving Water Partnership
December 2025
C40180.00
Participating Sonoma-Marin Saving
Water Partnership Members
Sources

1. Service area boundaries provided by respective agencies.

2. Basemap provided by ESRI.
0 8 16
(Scale in Miles)
Legend
City of Cotati Service Area
City of Petaluma Service Area
City of Rohnert Park Service Area
City of Santa Rosa Service Area
City of Sonoma Service Area
Marin Municipal Water District Service Area
North Marin Water District Service Area
Town of Windsor Service Area
Valley of the Moon Water District Service
Area
County Boundaries
Figure 1-1
1-3
Agenda Item #8.1:

Path: X:\C40180\Map\_.00\2025\09\ReportFigures.aprx
Notes

1. All locations are approximate.

Sonoma Marin Saving Water Partnership
December 2025
C40180.00
Service Area Boundary –
City of Sonoma
Sources

1. Service area boundary provided by City of Sonoma.

2. Basemap provided by ESRI.
0 1 2
(Scale in Miles)
Figure 1-2
Legend
City of Sonoma Service Area
County Boundaries
1-4
Agenda Item #8.1:

Section 2 2025 Demand & Conservation Update
Regulatory Context City of Sonoma
22 December 2025
2-1 EKI C40180.00
2 REGULATORY CONTEXT
This section provides the regulatory background for the requirements to project future demand in the 2025 UWMP. Although there are no updates to the UWMP regulations since 2020, the MCCWL and other state regulations will impact the 2025 UWMPs, as they will inform the water demand projections and conservation planning components.

2.1 UWMP Demand Projections Requirements
California Water Code (CWC) § 10631, excerpted below, describes the requirements to develop water demand projections that consider water use by customer sector, incorporate distribution system water loss, and account for anticipated water savings. Water demand projections herein were developed for the City using a land-use-based approach that is consistent with these requirements, and can be incorporated into the City’s 2025 UWMP.

CWC § 10631
A plan shall be adopted in accordance with this chapter that shall do all of the following:
…
(d) (1) For an urban retail water supplier, quantify, to the extent records are available, past and current water use, over the same five-year increments described in subdivision (a), and projected water use, based upon information developed pursuant to subdivision (a), identifying the uses among water use sectors, including, but not necessarily limited to, all of the following:
(A) Single-family residential.
(B) Multifamily.
(C) Commercial.
(D) Industrial.
(E) Institutional and governmental.
(F) Landscape.
(G) Sales to other agencies.
(H) Saline water intrusion barriers, groundwater recharge, or conjunctive use, or any combination thereof. (I) Agricultural.
(J) Distribution system water loss.
(2) The water use projections shall be in the same five-year increments described in subdivision (a). …
(d)(4) (A) Water use projections, where available, shall display and account for the water savings estimated to result from adopted codes, standards, ordinances, or transportation and land use plans identified by the urban water supplier, as applicable to the service area.
(B) To the extent that an urban water supplier reports the information described in subparagraph (A), an urban water supplier shall do both of the following:
(i) Provide citations of the various codes, standards, ordinances, or transportation and land use plans utilized in making the projections.

Agenda Item #8.1:

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(ii) Indicate the extent that the water use projections consider savings from codes, standards, ordinances, or transportation and land use plans. Water use projections that do not account for these water savings shall note that fact.

2.2 New Requirements for Water Use Efficiency

2.2.1 Making Conservation a California Way of Life
The State Water Resources Control Board (State Water Board) adopted a new Conservation Framework to implement Senate Bill 606 and Assembly Bill 1668 through the enactment of the MCCWL regulation in July 2024. The Conservation Framework requires each urban water supplier to calculate and comply with an annual Urban Water Use Objective (Objective) and to implement Commercial, Industrial, and Institutional (CII) Performance Measures, both of which must be reported on annually starting January 1, 2024 (although compliance with the Objective is not required until January 1, 2027).

As illustrated on Figure 2-1 below, the Objective is calculated as the sum of the following components: (1) residential indoor water use standard, (2) residential outdoor water use standard, (3) CII landscape outdoor water use standard (for landscapes with dedicated irrigation meters [DIMs]), (4) water loss standard, (5) allowable variances, and (6) bonus provisions. Per the latest guidelines released by the Department of Water Resources (DWR) and the State Water Board, agencies will need to assess whether they meet their overall Objective (i.e., they are not required to comply with the individual water use standards as long as they meet the overall Objective).

Figure 2-1 Components of Urban Water Use Objective
The components of the Objective Water use include the following:
• Indoor and Outdoor Residential. Indoor and outdoor residential include supplier-specific water use standards for indoor and outdoor single-family and multi-family residential use.

The standard for efficient residential indoor water use is expressed in gallons per capita per day (GPCD) and is currently set at 55 GPCD until January 1, 2025, when it lowers to 47 GPCD, and finally lowers to 42 GPCD beginning January 1, 2030 (Figure 2-2). The residential indoor water use budget is calculated by multiplying a supplier’s residential service area population by the residential indoor standard and by the number of days in the year. The standard for efficient residential outdoor water use is expressed as the landscape efficiency factor (LEF), a unitless number used to indicate the amount of water a supplier may need to deliver a healthy and efficient landscape in the service area, and represents plant factors and irrigation efficiency (Figure 2-2). The outdoor budget is then Agenda Item #8.1:

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calculated by multiplying the relevant outdoor LEF by landscape area, net evapotranspiration, and a unit conversion factor of 0.62; • CII Landscapes with Dedicated Irrigation Meters. The budget for CII water use associated with dedicated irrigation meters (DIMs) is calculated by multiplying the outdoor LEF (Figure 2-2) for the CII special landscape area, by area of the large landscape, net evapotranspiration, and a unit conversion of 0.62. However, the CII landscapes with DIMs budgets will not become effective until June 30, 2028; until then, the budget is equal to actual water deliveries to CII DIMs. In the future, urban retail suppliers will have the option of installing DIMs at “large landscapes” that are over 0.5 acres and currently served by mixed-use meters (MUMs) (see discussion of CII Performance Measures below); • Water Loss. Water loss represents “real water losses” or physical water losses from the pressurized potable water system (water mains and customer service connections) and the utility’s storage tanks, up to the point of customer consumption. These losses do not include apparent losses such as meter inaccuracies or theft. The water loss component is calculated based on the volumetric standards discussed in Section 2.2.2; • Variances. Variances are an additional volume of water that an urban retail water supplier may request to add to its Objective for a unique use that has a substantial impact on a supplier’s Objective. Types of variances include the following: (1) emergency response; (2) recycled water with high levels of total dissolved solids; and (3) other variances, which encompasses water use related to seasonal populations, dust control for horse corrals and animal exercise areas, irrigation of residential agricultural landscapes, water use for sustaining wildlife in ponds and lakes when required by regulation, and irrigation of existing trees. Approved variances can be included in a supplier’s budget for up to five years and have documentation demonstrating that the variance does not conflict with permit requirements;
• Bonus Incentives. Bonus incentives apply to potable reuse projects to help suppliers meet the Objective through alternative water sources. The bonus incentive is calculated by multiplying the urban retail water supplier’s potable reuse volume, in gallons, depending on where the potable reuse water is obtained (i.e., groundwater basin, reservoir, direct potable reuse project) by the portion of total potable water production delivered to residential and landscape irrigation connections for the reporting year. Suppliers must report and update the bonus incentive calculation annually. Required documentation includes data on potable reuse volumes, loss factors for groundwater recharge and recovery, and verification from relevant regulatory authorities.

The progression of the residential indoor water use standard, residential outdoor LEF, and CII landscape with DIMs outdoor LEF are summarized on Figure 2-2 below.

In addition, the Conservation Framework includes a number of requirements for CII Performance Measures, which include the following:
• Implementing a classification system for CII water users. Requires classification of CII accounts based on customer end use, and suppliers shall annually maintain at least a 95% classification rate of CII end users. CII accounts are to be classified based on customer end use, in accordance with the 18 Energy Star Portfolio Manager’s broad categories (e.g., Agenda Item #8.1:

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banking services, education, office, retail, utility, etc.), including four additional CII categories of laundries, landscapes with DIMs, water recreation, and car washes. • Converting MUMs to DIMs for CII customers with large landscapes, or employing in-lieu technologies combined with rolling out Best Management Practices (BMPs). Suppliers must install DIMs for CII customers with large landscapes (which include those over half an acre) or employ in-lieu technology (e.g., area median income [AMI]) and offer BMPs to CII customers.
• Providing BMP programs for CII customers. Suppliers must identify CII water users that exceed a recommended size, volume of water use, or another threshold. Options include identifying the top water users, identifying the top water users within CII classification categories, or identifying inefficient CII water users with the use of key business activity indicators. For CII customers identified, suppliers must design and implement conservation plans from a list of approved BMP themes.

The implementation timeline of the MCCWL regulatory requirements is illustrated on Figure 2-3.

2.2.2 Related Regulations with MCCWL Compliance Implications The following two regulations are separate from those embedded in the compliance requirements of MCCWL and are required to be reported on within annual Objective reporting:
• Water Loss Control. Urban water retailers are required to comply with State-assigned volumetric standards for real water loss. Suppliers must calculate system-specific water loss budgets by multiplying their State Board-assigned water loss standard by the number of days in the year and, depending on the units associated with the standard, by either the number of total service connections or the length of the distribution system. Suppliers with multiple systems must calculate an aggregate water loss budget by summing the estimated losses for each system.
• Nonfunctional Turf Irrigation Ban (AB 1572). The nonfunctional turf irrigation ban applies to turf (mowed grass maintained for aesthetic purposes) that does not provide recreational or community benefits, including CII properties, and common areas of homeowner associations. Water suppliers need to identify what landscapes fall under the ban and implement a plan to comply with the required schedule between 2027 and 2031, depending on the property type.

Agenda Item #8.1:

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Figure 2-2 Progression of Objectives Indoor and Outdoor Efficiency Standards Through 2040 Abbreviations:

CII = commercial, industrial, and institutional
LEF = landscape efficiency factors
SB = Senate Bill
Agenda Item #8.1:

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Figure 2-3 General Timeline of MCCWL Regulatory Requirements Abbreviations:

BMPs = best management practices
CII = commercial, industrial, and institutional
DIMs = dedicated irrigation meters
UWUO = Urban Water Use Objective
Agenda Item #8.1:

Section 3 2025 Demand & Conservation Update
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3 WATER USE CHARACTERISTICS
This section describes historical water use by customers within the City including changes in observed water use, changes in average water use per account over time, and estimates of indoor and outdoor water use. This information is used to provide context and background to support the projection of future water demands and estimates of potential conservation program benefits. The terms “water use,” “water consumption,” and “water demand” are used interchangeably in this document.

3.1 Historical Total and Per Capita Water Use
Table 3-1 and Figure 3-1 show the potable and recycled water use, total water use, total per capita water use, inclusive of both potable and recycled water 1, and residential per capita water use for the past 15 years, 2010 through 2024. It is noted that most recycled water use is by agricultural (i.e., non-urban) customers.

As shown in Table 3-1 and on Figure 3-1, total water use peaked in 2013 at a high of 2,295 acrefeet per year (AFY) before declining significantly in response to the historic 2014-2017 drought and the State’s water use reduction mandates. Water use partially rebounded through 2020, then declined again due to the 2021-2023 drought. While there was a modest increase following the drought in 2024 to 1,941 AFY, total water use remains below historical levels observed in the 2010s. The City began receiving recycled water in 2021. Recycled water use remains lower than 30 AFY, representing approximately 1.5% of total water use.

Total per capita water use has declined over the period, from a high of 178 gallons per capita per day (GPCD) in 2013 to a low of 139 GPCD in 2023. A similar trend was observed in residential per capita water use. These trends reflect the impact of water efficiency improvements, as well as demand hardening as structural and behavioral changes during droughts result in lasting water use reductions.

Historical water consumption per customer sector is provided in Table 3-2 and shown by sector groups on Figure 3-22. Figure 3-3 shows the proportional water use by sector group. The singlefamily residential (SFR) sector comprises the largest proportion of the City’s total water consumption (56.5%). By comparison, the proportional water use consumption for the other sectors includes the multi-family residential (MFR) sector at 14.8%; the combined commercial, industrial, and institutional (CII) sector at 19.8%; dedicated irrigation accounts at 7.6%; with recycled comprised of 1.3% of total water consumption. Separately, non-revenue water was estimated to be 7.8% of the City’s total water demand (Table 3-2). 1 Per-capita water use for purposes of comparing water use to SB X7-7 water conservation targets may be different, due to the prescriptive method by DWR for determining an agencies compliance population and total water use. SB X7-7 compliance will need to be separately addressed by the City’s UWMP. 2 Customer sectors are grouped into categories of SFR, MFR, CII total (mixed-use meters), irrigation, and recycled water.

Agenda Item #8.1:

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Table 3-1 Total and Per-Capita Water Use
Year
Potable Water
Use
(AFY) (a)
Recycled
Water Use
(AFY) (a)
Total Water
Use
(AFY) (b)
Total Per
Capita Water
Use
(GPCD) (c)
Residential
Per Capita
Water Use
(R-GPCD) (d)
2010 1,952 - 1,952 161 108
2011 1,932 - 1,932 149 99
2012 2,025 - 2,025 159 115
2013 2,295 - 2,295 178 120
2014 2,055 - 2,055 159 117
2015 1,762 - 1,762 136 87
2016 1,733 - 1,733 134 89
2017 1,994 - 1,994 154 100
2018 2,023 - 2,023 154 100
2019 2,067 - 2,067 157 101
2020 2,174 - 2,174 166 116
2021 1,877 27 1,904 145 97
2022 1,853 20 1,873 143 94
2023 1,777 22 1,799 139 89
2024 1,918 23 1,941 151 99
Abbreviations:

AFY = acre-feet per year
GPCD = gallons per capita per day
R-GPCD = residential gallons per capita per day
Notes:
(a) Water use data are based on water production data provided by City staff. Recycled water use includes both urban and agricultural uses.
(b) Totals may not sum due to rounding.
(c) Total per capita water use is calculated by dividing the annual water use by service area population (see Section 4) and the number of days in a year. (d) Residential per capita water use is calculated by dividing the annual residential water use by the service area population and the number of days in a year.

Agenda Item #8.1:

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Figure 3-1 Total Water Production and Per-Capita Water Use Abbreviations:

AFY = acre-feet per year
GPCD = gallons per capita per day
Agenda Item #8.1:

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Table 3-2 Annual Water Use by Customer Sector
Water Use Sector
Water Use (AFY) (a)
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Single Family 1,034 1,026 1,153 1,223 1,226 874 899 1,028 1,037 1,054 1,223 996 965 911 1,010 Multi-family 273 251 311 321 280 253 258 273 277 272 306 272 264 243 265 Commercial 243 236 281 280 275 261 244 255 253 249 373 355 337 334 353 Irrigation 116 101 132 139 104 111 103 160 151 123 136 114 121 116 135 Other 131 141 180 163 133 146 129 141 154 84 0.6 0.5 1.2 2 2 Recycled - - - - - - - - - - - 27 20 22 23
Total Water
Consumption (b) 1,797 1,755 2,057 2,126 2,018 1,644 1,633 1,857 1,872 1,781 2,039 1,764 1,708 1,628 1,789 Non-Revenue Water
(c)
154 177 (33) 169 37 119 100 137 152 285 135 140 165 171 152

7.9% 9.2% -1.6% 7.4% 1.8% 6.7% 5.8% 6.9% 7.5% 13.8% 6.2% 7.3% 8.8% 9.5% 7.8% Total Water Demand
(b) 1,952 1,932 2,025 2,295 2,055 1,762 1,733 1,994 2,023 2,067 2,174 1,904 1,873 1,799 1,941 Abbreviations:

AFY = acre-feet per year
Notes:
(a) Water use data are provided by City staff.
(b) Totals may not sum due to rounding.
(c) Non-revenue water is calculated as the difference between total production and total consumption.

Agenda Item #8.1:

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Figure 3-2 Annual Water Use by Sector Group
Figure 3-3 Proportional Water Use by Sector Group in 2024 Abbreviations:

AFY = acre-feet per year
CII = commercial, industrial, and institutional
Notes:

The CII Total sector group represents water use across all CII sectors with mixed-use meters.

The irrigation sector group represents water use across all CII dedicated irrigation meters.

Agenda Item #8.1:

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3.2 Water Use Trends by Customer Sector
This section discusses long-term trends in both total water use and per-account water use across customer sectors groups between 2010 and 2024. Figure 3-4 shows monthly water use with 12- month moving averages. Figure 3-5 summarizes the average annual water use per account. And Table 3-3 provides water use per customer sector. In total, these results provide insight into how each sector has responded to drought conditions, economic changes, and shifts in demographics. • SFR and MFR: In both sectors, total water use has remained the same when comparing 2010 and 2024 levels. Within both sectors, there are increases during 2010-2013 followed by notable reductions during drought periods and partial rebounds after the droughts.

Water use reductions during the drought periods are accompanied by diminished seasonality (Figure 3-4) that reflects likely reductions in outdoor irrigation in response to water use restrictions.
• Average per-account water use was highest in 2013-14 in SFR and MFR respectively and rose again in 2020; likely due to stay-at-home measures during the beginning of the pandemic (Figure 3-5). Per-account use has begun to rebound in 2023-2024 and current water use are lower than historical levels.
• CII Total: The CII sectors exhibited similar responses the droughts and increases during wetter years but increased in both total and per account use over 2010-2024. These shifts may be tied to long-term changes in business activity and employment in the City. • Irrigation: The irrigation sector showed reductions during drought years with a steeper decline during 2014-2015. Per account water use shows signs of a partial rebound in 2023- 2024 but remains lower than 2017-2019 levels.
• Recycled water: Recycled water use began in 2021 and has remained relatively steady in total volume over time. No per account water use information was available.

Agenda Item #8.1:

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Figure 3-4 Monthly Water Use and 12-Month Moving Average Abbreviations:

AF = acre-feet
CII = commercial, industrial, institutional
Notes:

The CII Total sector group represents water use across all CII sectors with mixed-use meters.

The irrigation sector group represents water use across all CII dedicated irrigation meters.

Agenda Item #8.1:

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Table 3-3 Average Per Account Water Use by Sector Group Water Use Sector
Water Use Per Account (GPD/Account)
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 Single-Family
Residential 265 265 296 305 313 223 229 262 261 265 304 247 239 226 251 Multi-Family
Residential (a) 905 833 986 1,031 914 814 824 874 889 872 989 863 842 772 842 CII Total (b) 648 698 751 772 822 776 731 764 768 758 893 855 813 806 853 Irrigation (c) 1,385 1,199 1,401 1,510 1,063 1,111 1,011 1,569 1,875 1,442 1,365 1,103 1,171 1,115 1,299 Other 614 648 781 696 573 622 540 588 687 370 - - - 9 8 Abbreviations:

CII = commercial, industrial, and institutional
GPD = gallons per day
Notes:
(a) The water use per account for multi-family residential customers measures water use at the master meter level, which can serve multiple units or the entire complex. This does not reflect water use per dwelling unit, as many properties are not individually submetered. (b) Based on the total water use and number of accounts across all CII sectors with mixed-use meters. (c) Based on the total water use and number of accounts across all sectors with dedicated irrigation meters.

Agenda Item #8.1:

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Figure 3-5 Average Per-Account Water Use by Sector Group Abbreviations:

CII = commercial, industrial, and institutional
GPD = gallons per day
Notes:

The CII Total sector group represents water use across all CII sectors with mixed-use meters.

The irrigation sector group represents water use across all CII dedicated irrigation meters.

3.3 Estimated Indoor and Outdoor Water Use
Water use within the City varies seasonally (Figure 3-6), primarily driven by increased irrigation needs in the summer compared to the more limited irrigation water use during the wetter and cooler winter months. The most pronounced seasonal fluctuations occur in the irrigation and recycled water sectors, where water use is limited to outdoor irrigation and water use is minimal during the winter.

In contrast, SFR, MFR and the CII sector include water use from mixed-use meters and records both indoor and outdoor water use. In the SFR sector, summer water use is approximately double that of winter water use. The MFR and CII sectors show less seasonality, with summer water use about 81% and 74% higher than winter water use, respectively.

It is important to note that many MFR and CII customers have dedicated irrigation meters that are included in the irrigation sector, not within the MFR and CII mixed-use sectors. As a result, the outdoor water use estimated for MFR and CII sectors herein reflects only the portion of Agenda Item #8.1:

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irrigation that remains on the domestic or mixed-use accounts. Some CII industries, such as restaurants, manufacturing, or facilities with cooling needs, may also experience seasonal variation in indoor water use, contributing to the modest increase in CII summer demands.

Figure 3-6 Average Monthly Water Use, 2010-2024
Abbreviations:

AF = acre-feet
CII = commercial, industrial, and institutional
Notes:

The CII Total sector group represents water use across all CII sectors with mixed-use meters.

The irrigation sector group represents water use across all CII dedicated irrigation meters.

A Seasonal Adjustment Method was used to estimate the relative proportions of water use that are used indoors versus outdoors in non-irrigation sectors. The methodology is further described in Appendix A. The results of this estimate are shown on Figure 3-7.

Aside from the dedicated irrigation and recycled sectors (100% outdoor water use), SFR water use is estimated to have the highest proportion of outdoor water use at 63%, followed by the CII sector of mixed-use accounts at 45%. The MFR sector of mixed-use accounts has an estimated 43% outdoor water use, corresponding to the lesser seasonality observed in this sector. These values should be interpreted with the understanding that a substantial portion of MFR and CII landscape irrigation is already captured in the irrigation sector through dedicated irrigation meters. Given their landscape-only demands, MFR and CII dedicated irrigation accounts represent meaningful opportunities for outdoor conservation programs.

Agenda Item #8.1:

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Figure 3-7 Estimated Indoor and Outdoor Water Use, 2024 Abbreviations:

CII = commercial, industrial, and institutional
Notes:

The CII Total sector group represents water use across all CII sectors with mixed-use meters.

The irrigation sector group represents water use across all CII dedicated irrigation meters.

Agenda Item #8.1:

Section 4 2025 Demand & Conservation Update
Conservation Program Participation City of Sonoma
22 December 2025
4-1 EKI C40180.00
4 CONSERVATION PROGRAM PARTICIPATION
This section evaluates past participation in water conservation programs by City customers, including presenting historic program participation and estimated water savings associated with program participation. The purpose of this section is to document program participation and savings to inform future program selection and implementation, and to support the demand management measure (DMM) reporting required in the UWMP under CWC § 10631(e). 3

4.1 Conservation Programs
The description of water conservation programs, eligible customer classes, and program run dates provided by the City to their customers is summarized in Table 4-1 below. The City currently implements two conservation programs offered directly to customers.

Table 4-1 Description of Conservation Programs
Program Description
Eligible
Customer
Class(es)
Program
Run Dates
HECW Rebate Program
Rebate of $50 on high-efficiency clothes
washers. Rebates are available for models
listed under Tier 2 and Advanced Tier on
the current Consortium for Energy
Efficiency’s “Super Efficient Home
Appliance Initiative Clothes Washer
Qualifying Product List.”
SFR (Indoor) 2009 -
Current
Turf Rebate Program
Rebate for removing turf from their
landscapes. Rebates are $1.00 per sq ft of
lawn removed with a total maximum
rebate of $1,000 for residential customers
and $3,000 for commercial customers.

SFR, MFR, CII
(Outdoor)
2006 -
Current
Abbreviations:

HECW = High Efficiency Clothes Washer
SFR = Single Family Residential
sq ft = square feet
In addition to programs offered by the City, several regional programs are offered through the SMSWP, including: (1) education and outreach to schools, (2) public outreach and educational workshops, (3) Qualified Water Efficient Landscaper (QWEL) Training, and (4) garden tours. The full Report will additionally present participation in these SMWSP programs after school year 2024-25 data are available.
3 The information presented herein supports a portion of the required DMM analysis, focusing on device and education-focused programs. Additional details regarding customer billing rates and structure, conservation staffing levels, customer metering, etc. are required under CWC § 10631(e) but not addressed herein.

Agenda Item #8.1:

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4.2 Historical Conservation Program Participation
Table 4-3 summarizes participation in the City’s conservation programsfrom 2006 through 2024.

Darker shading indicates higher participation values. The table shows the total number of participants in each program as a percentage of the total number of accounts of the predominant sector. This percentage serves as a measurement of program saturation, (i.e., how extensively the program has been adopted within the target customer base) and whether there remains future potential from the program. Figure 4-1 further illustrates the data included in Table 4-3, showing the participation by end use, sector group, or program categories, and turf replacement square footage over time.

Among the programs offered by the City, the programs that reached the largest number of customers and their respective sector participation rates included:
• HECW Rebate Program, 8% in the SFR sector; and
• HET Rebate Program, 0.3% in the SFR sector.

As shown on Figure 4-1, graph D, the HECW rebate program has seen low recent engagement.

Through the Turf Rebate Program, over 360,000 square feet of turf have been removed. Per Figure 4-1, graph C, participation in this program has fluctuated with peak activity during early implementation and drought years.

Table 4-2 summarizes participation in the regional SMWSP water conservation direct instruction school education and outreach programs from the 2020-2021 through 2024-2025 school years.

Over this period, 2,337 students were reached by direct instruction. Additional students were reached through indirect instruction such as assemblies, video and poster contests, and other educational materials.

Table 4-2 Participation in SMSWP School Education Programs, Direct Instruction Grade Level
Number of Students Reached by School Year
2020-2021 2021-2022 2022-2023 2023-2024 2024-2025
Kindergarten - 42 96 167 179
1st – 3rd Grade 65 65 107 352 502
4th – 5th Grade 69 25 18 138 57
Middle/High School - 151 128 28 148
Total 134 283 349 685 886

4.3 Estimated Savings from Past Conservation Programs
The Alliance for Water Efficiency (AWE) model 4 was used to estimate water savings associated with the implementation of all device or turf replacement and audit programs identified in Table 4-3 for the period of 2010 to 2024. Water savings estimates were based on AWE model default values and other literature values as needed. The specific assumptions used in this 4 Alliance for Water Efficiency, Water Conservation Tracking Tool Version 4.3.

Agenda Item #8.1:

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assessment are presented in Appendix B. The results of this analysis are presented in Table 4-4 and illustrated on Figure 4-2. It is estimated that conservation programs included in this assessment resulted in active savings of 284 AF between 2010 and 2024.

As shown on Figure 4-2, the most successful program types in terms of estimate savings include the following, listed in order of savings:
• Turf Replacement (Turf Rebate Program);
• Clothes Washers (HECW Rebate Program); and
• HET (HET Rebate Program).

In addition, over this period, it is estimated that 130 AF was saved through passive savings. 5 Thus, total active and passive savings are estimated to be 414 AF. 5 Passive water savings are water savings associated with the natural replacement of water using fixtures and devices with higher efficiency ones, due to plumbing code and market changes. Passive savings are estimated for the whole service area.

Agenda Item #8.1:

Table 4-3 Summary of Conservation Program Participation City of Sonoma, Sonoma-Marin Saving Water Partnership
Sector (a) Indoor/
Outdoor
2006200720082009201020112012201320142015201620172018201920202021202220232024 Total
HECW Rebate Program SFR Indoor Clothes Washers - - - 23 73 54 25 28 23 19 9 2 9 2 2 3 1 2 3 278 7.7% HET Rebate Program SFR Indoor HET - - - - 5 1 2 0 0 1 2 1 - - - - - - - 12 0.3% Turf Rebate Program SFR Outdoor Turf Replacement 4,915 3,948 21,932 102,114 16,461 19,941 8,927 8,476 31,604 58,501 30,875 6,586 5,982 5,554 3,205 2,428 10,930 15,301 6,877 364,557 - Abbreviations
HET = High Efficiency Toilet
HECW = High Efficiency Clothes Washer
SFR = Single-family residential
Notes
(a) Predominant sector for program participants.
(b) Participation is calculated as a percentage of total accounts of the predominant sector indicated. (c) Colored shading is added for visualization purposes. Green shading represents higher participation values.

Program Name
Pct. of
Accounts
(b)
Total Turf Removed (square feet)
End Use Number of Program Participants
Program Category
EKI C40180.00 4-4
EKI Environment & Water, Inc.

December 2025
Agenda Item #8.1:

Power BI Desktop
D. Participants by Year and Program Category
0 20
40 60
80 Year
Participants
2010 2015 2020
Program Category
Clothes Washers
HET
Figure 4-1
Conservation Program Participation
City of Sonoma, Sonoma-Marin Saving Water Partnership
EKI C40180.00
EKI Environment & Water, Inc.

December 2025
Abbreviations:

CII = commercial, industrial, institutional
HET = high efficiency toilet
Notes:
(a) See Table 4-3 for program end use, sector, category information and detailed program participation data. (b) Programs are summarized by Residential, CII, Irrigation, or Multiple sector groups based on their targeted sectors. Programs that cannot be exclusively assigned to the Residential, CII, Irrigation sector groups are assigned to the Multiple sector group.

B. Participants by Year and Sector Group
0 20
40 60
80 Year
Participants
2010 2015 2020 2025
Sector Group (b) Residential
A. Participants by Year and End Use
0 20
40 60
80 Year
Participants
2010 2020
End Use Indoor
C. Turf Replacement Square Footage
0K
50K
100K
Year
Square Footage
2010 2020
4-5
Agenda Item #8.1:

Table 4-4 Estimated Water Savings Achieved by Conservation Programs and Passive Savings City of Sonoma, Sonoma-Marin Saving Water Partnership
Sector (a) Indoor/
Outdoor
201020112012201320142015201620172018201920202021202220232024 HECW Rebate Program SFR Indoor Clothes Washers 2 3 3 4 4 5 5 5 5 5 5 5 5 5 6 68 HET Rebate Program SFR Indoor HET 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0 0 1.1 Turf Rebate Program SFR Outdoor Turf Replacement 2 4 5 6 9 16 19 20 21 21 20 18 18 19 16 214 Conservation Program Water Savings (Active Savings) 3 7 8 10 14 21 24 25 26 27 25 23 24 24 22 284 Passive Water Savings (c) 9 9 10 10 13 13 8 7 10 9 8 7 7 6 5 130 Total Water Savings 13 15 18 20 27 33 32 33 36 36 33 31 30 30 27 414 Abbreviations
HET = High Efficiency Toilet SFR = Single-family residential HECW = High Efficiency Clothes Washer
Notes
(a) Predominant sector for program participants.
(b)
(c)
Water savings are estimated per the AWE model based on program participation data. Program water saving assumptions are included in Appendix B.

Passive water savings are water savings associated with the natural change out of water using fixtures and devices with higher efficiency ones, due to plumbing code and market changes. Passive savings are estimated for the whole service area.

Water Savings Type
End Use Estimated Annual Water Savings (AFY) (b) Cumulative Water
Savings (AF)
Program Category
EKI C40180.00 4-6
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December 2025
Agenda Item #8.1:

Power BI Desktop Figure 4-2
Estimated Annual Water Savings Achieved by Conservation Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
EKI C40180.00
Abbreviations:

CII = commercial, industrial, institutional
HET = high efficiency toilet
Notes:
(a) See Table 4-4 for program end use, sector, category information and detailed savings by program. (b) Programs are summarized by Residential, CII, Irrigation, or Multiple sector groups based on their targeted sectors. Programs that cannot be exclusively assigned to the Residential, CII, Irrigation sector groups are assigned to the Multiple sector group. (c) Program categories with minimal historical savings may not be visible from this figure.

A. Active Conservation Savings by Year and End Use
0 10
20 30
Year
Annual Savings (acre-feet)
2010 2015 2020
End Use Indoor Outdoor
B. Active Conservation Savings by Year and Sector Group 0 10
20 30
Year
Annual Savings (acre-feet)
2010 2015 2020
Sector Group (b) Residential
EKI Environment & Water, Inc.

December 2025
C. Active Conservation Savings by Year and Program Category 0 10
20 30
Year
Annual Savings (acre-feet)
2010 2012 2014 2016 2018 2020 2022 2024
Program Category (c)
Clothes Washers
HET
Turf Replacement
4-7
Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-1 EKI C40180.00
5 WATER DEMAND PROJECTIONS
The purpose of this section is to document the basis, methodology, and resulting projected demands for the City through 2050. As described in more detail below, the future water demands for the City were estimated by:
1) Applying an estimated growth rate to accounts within each water use sector based on projected population and employment growth rates,
2) Evaluating and selecting water demand factors for each water use sector based on review of recent average per account water use representing three scenarios, 3) Estimating future passive savings using the Alliance for Water Efficiency (AWE) Water Conservation Tracking Tool (AWE model), and
4) Calculating estimated future water demand that incorporates the anticipated account growth, water demand factors, and estimated future passive water savings.

This methodology is consistent with CWC § 10631(d)(4)(A), which requires that “Water use projections, where available, shall display and account for the water savings estimated to result from adopted codes, standards, ordinances, or transportation and land use plans identified by the urban water supplier, as applicable to the service area.” The assumptions used as the basis for demand projections were developed in close coordination with the City and reflect a land-use based approach consistent with the City’s community planning.

5.1 Basis for Account Growth Projections
Baseline water demand is estimated by multiplying the number of accounts by the sector-specific demand factors, before applying other adjustment factors. In order to estimate how accounts will grow within the City, recent historical account growth within the City was considered, as well as projected future growth in population and employment. As described below, it was assumed that depending on the customer sector, the number of accounts will grow at the same rate as the projected population or employment growth.

Table 5-1 identifies the growth projection assumptions applied to each potable water use sector per the City’s direction and identifies the average annual growth rate in accounts observed within the City from 2010-2024 to provide context for the growth assumptions. Growth for the residential sectors is based on the City’s General Plan 2023-2031 Housing Element population projections, which are lower than the historical growth observed in the single family residential sector from 2015-2024, but higher in the multifamily sector for that same historical time period.

The projected growth for the CII and “other” sectors is based on the Association of Bay Area Governments (ABAG) and Metropolitan Transportation Commission (MTC) Plan Bay Area 2050 employment projections (ABAG, 2021). Irrigation account growth is based on assumptions relative to the multifamily residential and CII account growth. There are currently no plans for expansion of the recycled water system, and thus no account growth is assumed as the system is at capacity, which is consistent with the City’s 2020 UWMP (EKI, 2021).

Table 5-2 presents the City’s historical population from the California Department of Finance estimates published in 2024 (DOF, 2024a), which is adjusted by incorporating an additional population of 955 to account for customers outside the City limits. Population growth projections Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-2 EKI C40180.00
for the City are based on the City’s General Plan 2023-2031 Housing Element (Sonoma, 2023), which are aligns with and is inclusive of the growth identified in the Association of Bay Area Governments (ABAG) and Metropolitan Transportation Commission (MTC) Plan Bay Area 2050 population projections (ABAG, 2021). The planning horizon for the 2025 UWMP is 2050; however, the General Plan 2023-2031 Housing Element projections extend only through 2040. For purposes of demand projections, it was assumed that the projected growth rates from 2035 through 2040 extend through 2050. The City’s historical employment estimates are per the U.S.

Census Bureau Longitudinal Employer-Household Dynamics (LEHD) Origin-Destination Employment Statistics (U.S. Census Bureau, 2025) and employment projections are based on ABAG and MTC’s Plan Bay Area 2050 (ABAG, 2021).

Table 5-1 Historical and Projected Account Growth Rate by Customer Sector Water Use Sector Basis for Account Growth
Average Annual Growth of Accounts
(a)
Historical
(2015-2024) (b)
Projected Growth
Through 2050
Single Family (c) Housing Element (d) 0.34% 0.19%
Multifamily (c) Housing Element (d) 0.16% 0.19%
CII ABAG Employment (e) 2.59% 0.11%
Irrigation Relative to MFR and CII Accounts 0.50% 0.15% Other ABAG Employment (e) -2.23% 0.11%
Recycled (f) No Growth - -
Abbreviations:

ABAG = Association of Bay Area Governments
CII = commercial, industrial, institutional
MFR = multifamily residential
SFR = single family residential
UWMP = Urban Water Management Plan
Notes:
(a) Growth of the number of accounts is presented on an average annual basis over the indicated period. When applied to account growth, the specific growth rate between each 5-year period was applied.
(b) Historical annual growth percentage is based on the historical number of accounts. (c) SFR and MFR percentages of total population are assumed to be the same percentage split as in 2024.
(d) The Housing Element household projections project a growth of 311 households over the eight year period, which aligns and is inclusive of the 30 new households provided by the ABAG projections (ABAG, 2021) over the 10-year period between 2025 and 2035. (e) ABAG employment projections per ABAG, 2021.
(f) No recycled water growth is projected, consistent with the City's 2020 UWMP.

Agenda Item #8.1:

2020 2021 2022 2023 2024 2025 2030 2035 2040 2045 2050
Historical Population Estimates (a) 11,725 11,686 11,669 11,591 11,487 -- -- -- -- -- -- -- -- Housing Element Population Projections (b) -- -- -- -- -- 11,542 12,088 12,088 12,088 12,088 12,088 5% 0.19% Single Family Population (c) -- -- -- -- -- 7,597 7,957 7,957 7,957 7,957 7,957 5% 0.19% Multifamily Population (c) -- -- -- -- -- 3,945 4,131 4,131 4,131 4,131 4,131 5% 0.19% Historical Employment Estimates (d) 7,174 6,858 7,871 -- -- -- -- -- -- -- -- -- -- ABAG Employment Projections -- -- -- -- -- 7,871 7,872 7,873 7,943 8,014 8,084 3% 0.11% Abbreviations:
-- = not available
ABAG = Association of Bay Area Governments
Notes:
(a) Historical population estimates per DOF, 2024a and adjusted by incorporating an additional population of 955 to account for customers outside the City limits. (b)
(c)
(d) Historical employment estimates per (U.S Census Bureau, 2025).

Population
Employment
Category
Single family residential and multifamily residential percentages of total population are assumed to be the same percentage split as in 2024.

Population projections are based on the City's 2021-2023 Housing Element. The Housing Element household projections projects a growth of 311 households over the 8 year period, which aligns and is inclusive of the 30 new households provided by the ABAG projections (ABAG, 2021) over the 10-year period between 2025 and 2035.

Table 5-2 Population and Employment Growth Projections
City of Sonoma, Sonoma-Marin Saving Water Partnership
Total Growth
Rate
2025-2050
Average Annual
Growth Rate
2025-2050
Growth Projections
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Agenda Item #8.1:

Power BI Desktop
Population
11,000
11,500
12,000
Year
Population
2010 2020 2030 2040 2050
Source Historical Population Projected Population
Employment
6K
8K
10K
Year
Employment
2010 2020 2030 2040 2050
Source Historical Employment Projected Employment
Figure 5-1 Population and Employment Projections
City of Sonoma, Sonoma-Marin Saving Water Partnership
*Axis scale is truncated to show detail.
*Axis scale is truncated to show detail.

EKI C40180.00
EKI Environment & Water, Inc.
5-4 December 2025
Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-5 EKI C40180.00

5.2 Planned Development Within the Service Area
There are no development projects additional to the growth assumptions identified by City staff.

5.3 Water Demand Factors
Water use rates are influenced by a variety of factors, including weather, economic recession, and state and local regulations, among other drivers. Given this, selecting a “representative” baseline is important to developing the land-use based water demand factors to estimate baseline water use by existing customers, which can then be extrapolated and applied to future growth within the City. Table 5-3 shows the water demand factors used to estimate baseline water demand.

Table 5-3 Selected Water Demand Factors
Water Use Sector Group Water Demand
Factor Units Basis for Demand Factor
Water Consumption
Single Family 265 GPD/account Maximum of 2017-2019
Multi-family 889 GPD/account Maximum of 2017-2019
CII Total (a) 853 GPD/account Maximum of 2017-2019
Irrigation 1,429 GPD/account Partial Rebound from 2024
Other 687 GPD/account Maximum of 2017-2019
Non-Revenue Water
Apparent Losses 4.8 GPD/connection
Real Losses 28 GPD/connection CY 2023 Water Loss Audit
Unbilled Authorized 0.79 GPD/connection
Abbreviations:

CII = commercial, industrial, institutional
CY = calendar year
GPD = gallons per day
Notes:
(a) Represents the combined demands of all CII sectors with mixed-use meters. The CII sectors are evaluated as a single group as the same growth rate is applied uniformly across all CII sectors; therefore, it is mathematically equivalent to projecting each sector individually and summing the results. Final projected demands are then allocated back to each CII sector based on their relative proportions within the CII Total group.

5.3.1 Potable Water
Water demand factors based on historical use within the City were used as the basis of future demand projections for potable water accounts. As discussed in Section 3.2, the City’s per account water use declined sharply during the 2014-2017 and 2021-2023 droughts, but increased in the residential sectors during the COVID-19 pandemic, followed by rebound to pre-drought levels. Since the single family residential, multifamily residential, CII total, and other 2024 per account water use remains within 75% of their 2017-2019 levels, these sector water demand factors are based on the maximum per account annual water use observed from 2017-19, which reflects the lower levels of recent water use but considering some rebound to pre-2020 Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-6 EKI C40180.00
conditions. Since the irrigation sector 2024 recycled water use per account falls below 75% of 2017-2019 levels, the water demand factor for irrigation is developed based on a partial rebound from 2024 per account annual water use, recognizing some increase is likely, but a full return to pre-drought and pre-pandemic conditions is not anticipated.

5.3.2 Non-Revenue Water and Water Loss
Non-revenue water is water that has been produced but not billed and thus does not generate revenue for the supplier. To more fully capture total water use within the City, non-revenue water is estimated based on a sum of (1) unbilled authorized uses (such as water for fighting fires and flushing mains), (2) apparent water loss due to metering inaccuracies, and (3) real water loss due to distribution system leaks. Rates of non-revenue water in gpd per service connection are based on the City’s Calendar Year 2023 water loss report.

5.4 Passive Water Savings Estimate
Passive water savings are the water savings associated with the natural replacement of older toilets, showerheads, clothes washers, and other water using appliances with newer high efficiency devices that are available due to both market shifts and increasing efficiency mandated by the building code and other regulatory requirements. The AWE model was used to estimate future passive savings within the City (AWE, 2021). These future water savings are a result of plumbing/energy codes interacting with the natural replacement of toilets, showerheads, and other water using appliances whose current or future efficiency is dictated by national, state, or local code requirements. The AWE model calculates efficient plumbing fixture saturation rates and takes into account historical and projected replacement of plumbing fixtures by utility programs as well as natural replacement.

The AWE model also considers estimates of historical population, residential building stock, number of accounts, and projected population and account growth to estimate future passive savings. The estimated passive savings are presented in Table 5-4 and are subtracted from the water demand projected based on the water demand factors described in Section 5.3 above.

Passive savings are only applied to potable water use.

Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-7 EKI C40180.00
Table 5-4 Projected Demand and Passive Conservation
Water Use Sector
Projected Demand (AFY) (a)
2025 2030 2035 2040 2045 2050
Potable Water
Baseline Potable Water Demand 2,158 2,230 2,231 2,237 2,243 2,248 Passive Water Conservation (b) (10) (61) (81) (94) (104) (112) Total Potable Water Demand 2,147 2,169 2,151 2,143 2,138 2,137 Non-Potable Water
Recycled Water (c) 55 55 55 55 55 55
Total Non-Potable Water Demand 55 55 55 55 55 55
Total Water Demand 2,202 2,224 2,206 2,198 2,193 2,192
Abbreviations:

AFY = acre-feet per year
AWE = Alliance for Water Efficiency
UWMP = Urban Water Management Plan
Notes:
(a) Water demand projections are estimated based on growth in accounts shown in Table 5-1 and the water demand factors identified in Table 5-3. Non-revenue water projections are estimated by water loss factors shown in Table 5-3 and the total growth in number of services from all sectors.
(b) Passive water savings are based on the AWE Conservation Tracking Tool. (c) No recycled water growth is projected, consistent with the City's 2020 UWMP.

5.5 Projected Water Demand Through 2050
Future potable water demand was projected for each sector based on their respective demand factors, non-revenue water estimated as a proportion of total potable water production, and estimated passive savings, and is shown in Table 5-4. Given that there are no plans currently to expand the recycled water system, recycled water use projections are limited to the projections consistent with the City’s 2020 UWMP. Potable water demand is projected to increase to 2,137 AFY in 2050, which is an 11% increase over 2024 water demand.

Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-8 EKI C40180.00
Table 5-5 Projected Water Demand by Sector
Water Use Sector
Projected Demand (AFY) (a)
2025 2030 2035 2040 2045 2050
Potable Water
Single Family Residential 1,067 1,088 1,078 1,071 1,066 1,063 Multifamily Residential 279 280 275 272 270 268
Commercial 352 343 339 338 338 339
Institutional 149 150 152 153 154 155
Other 129 129 129 130 131 132
Non-Revenue Water 172 179 179 179 179 180
Total Potable Demand (b) 2,147 2,169 2,151 2,143 2,138 2,137 Non-Potable Water
Recycled Water 55 55 55 55 55 55
Total Non-Potable Water Demand 55 55 55 55 55 55
Abbreviation:

AFY = acre-feet per year
Notes:
(a) Water demand projections are estimated based on growth in accounts shown in Table 5-1 and the water demand factors identified in Table 5-3. Non-revenue water projections are estimated by water loss factors shown in Table 5-3 and the total growth in number of services from all sectors.
(b) Totals may not sum due to rounding.

Agenda Item #8.1:

Power BI Desktop
Potable Water Demand
1,800
2,000
2,200
Year
Potable Water Demand (AFY)
2010 2020 2030 2040 2050
Source Historical Demand Projected Demand
Recycled Water Demand
0 20
40 60
Year
Recycled Water Demand (AFY)
2020 2025 2030 2035 2040 2045 2050
Source Historical Demand Projected Demand
Figure 5-2 Water Demand Projections
City of Sonoma, Sonoma-Marin Saving Water Partnership
Abbreviations:

AFY = acre-feet per year
*Axis scale is truncated to show detail.

EKI Environment & Water, Inc.

EKI C40180.00 5-9 December 2025
Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-10 EKI C40180.00

5.6 Projected Compliance with UWUOs
To forecast the City’s Objective compliance, a analysis was conducted comparing the City’s projected water use to its Objectives for 2025, 2030, 2035, and 2040. The projected water demands subjective to the Objectives and the corresponding Objectives are calculated using the following data sources and assumptions:
• Projected population, water use components subjective to the objectives (e.g., residential water use and dedicated irrigation water use), and real water loss described in Sections

5.1 and 5.5;
• Decreasing Objective water use standards through 2040 as described in Section 2.2.1; • Residential landscape area based on values reported in the City’s FY 2023-24 UWUO Annual Report and increasing proportional to population projections; • Existing (2025) CII landscape area on DIMs irrigated with potable water estimated from projected 2025 water use assuming a LEF of 0.80; and
• Future CII landscape area on DIMs increasing proportionally with City’s irrigation and recycled water accounts; and
• CII landscape area on DIMS irrigated with recycled water (i.e., Special Landscape Area) estimated from a water use of 55 AFY assuming a LEF of 1.0.

The results of this analysis show that the City is anticipated to comply with its Objectives through 2035, but in 2040 the City’s water use is anticipated to be slightly (i.e., 1%) above its Objective, as shown below in Table 5-6 and Figure 5-3. Figure 5-4 compares projected values of each Objective component from 2025 through 2040 to examine relative contributions to Objectives compliance. However, agencies are only assessed against the overall Objective (i.e., they are not required to comply with the individual water use standards as long as they meet the overall Objective).

Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-11 EKI C40180.00
Table 5-6 Actual and Projected Water Use vs. Urban Water Use Objectives Year (a)
Actual and Projected
Water Use Subject to
the Objectives (b)
(AFY)
UWUO
(AFY) Reduction Required
FY 2023-2024 1,438 1,961 -
2025 1,694 1,847 -
2030 1,723 1,966 -
2035 1,709 1,749 -
2040 1,700 1,686 1%
Figure 5-3 Actual and Projected Water Use vs. Urban Water Use Objectives Abbreviations:

AFY = acre-feet
FY = fiscal year
UWUO = Urban Water Use Objective
Notes:
(a) Calendar years unless otherwise noted.
(b) Only includes the water use components that are subject to the Objective.

Agenda Item #8.1:

Section 5 2025 Demand & Conservation Update
Water Demand Projections City of Sonoma
22 December 2025
5-12 EKI C40180.00
Figure 5-4 Projected Water Use vs. Urban Water Use Objectives by Component Abbreviations:

AFY = acre-feet per year
CII = commercial, industrial, and institutional
DIM = dedicated irrigation meter
UWUO = Urban Water Use Objective
Notes:

This figure provides a comparison for each component to examine their relative contributions to Objectives compliance. However, agencies are only assessed against the overall Objective (i.e., they are not required to comply with the individual water use standards as long as they meet the overall Objective.

Agenda Item #8.1:

Section 6 2025 Demand & Conservation Update
Conservation Measures Update City of Sonoma
22 December 2025
6-1 EKI C40180.00
6 CONSERVATION MEASURES UPDATE
The following section evaluates current and potential conservation programs and measures for both the City and the SMSWP. The purpose of this section is to compile programs and measures that are prioritized by both the City and by all Water Contractors in the SMSWP collectively and calculate the potential water savings and economic feasibility of the programs. Section 6.1 discusses the methodology used to prioritize conservation programs and measures. Section 6.2 describes the programs and measures given high priority for regional implementation by the nine Water Contractors collectively, and Section 6.2.3 describes programs and measures given high priority by the City. Next steps will include analyzing the potential water savings and cost-benefit for those programs selected by the City as both individual programs and in select program portfolios. By assessing the feasibility of these programs, the City can make more informed decisions regarding program selection and implementation.

6.1 Methodology for Screening of Potential Water Conservation Measures A comprehensive ranking list of over 100 conservation programs and measures was developed (Appendix C) to help agencies prioritize future conservation efforts and update the suite of common measures for modeling and future implementation, as required for the 2025 UWMPs.

The Water Contractors ranked their priority projects and measures, which will contribute to the broader goals of forecasting demand through 2050, evaluating demand management strategies, and meeting regulatory goals.

The list includes the measures from the prior (2015 and 2020) screenings, minus those that are now obsolete, and new measures and technologies. New measures came from the library of the AWE Conservation Tracking Tool, version 4.0, and other identified measures per literature or implemented by other suppliers, including those that are available to the industry since 2020.

The list also included measures currently implemented by the Water Contractors, and the priority rankings selected in 2020.

Each of the nine Water Contractors wasfirst asked to review and identify any additional programs to add to the ranking list. Following receipt of feedback from the Water Contractors, each Water Contractor was asked to rank the list and identify:
• Priority (on a scale of one to five, with five being the highest priority) as a program to be implemented regionally through the SMSWP;
• Priority (on a scale of one to five, with five being the highest priority) as a program to be implemented locally through their agency;
• The current implementation status with options of (1) currently administered by their agency, (2) previously administered by their agency, or (3) current regional program through SMSWP.

The list of water conservation measures is organized into four categories, specifically: (1) agency actions and water rates, (2) public outreach and education, (3) device-based and financial incentive programs, and (4) policies and regulations.

Agenda Item #8.1:

Section 6 2025 Demand & Conservation Update
Conservation Measures Update City of Sonoma
22 December 2025
6-2 EKI C40180.00

6.2 Screening of Conservation Measures for Regional Implementation The regional results of the water conservation measures prioritization screening are summarized for all Water Contractors combined, representing overall regional priorities and preferences (Table 6-1), which shows (1) the average prioritization ranking for all Water Contractors for each program for regional implementation, (2) the percentage of Water Contractors that prefer each program to be implemented at the regional level, and (3) indication of each measure as a current SMSWP program or not.

Of the 116 measures and programs ranked, the Water Contractors screened these down to 11 high priority measures that received an average score of three or more and were comprised of two of the four categoriesincluding Public Outreach and Education Based Conservation Programs and Devise-Based and Financial Incentive Programs.

6.2.1 Public Outreach and Education-Based Conservation Programs Of the 14 public outreach and education-based water conservation programs included in the screening, the Water Contractors identified the following eight programs as high priority (average score of three or higher), with a preference for regional implementation through SMSWP:
1) Public Outreach through Print & Electronic Media - Focused on Outdoor Irrigation 2) School Education Programs
3) Promote QWEL Training
4) Public Outreach through Print & Electronic Media - Focused on Indoor Conservation 5) Educational Workshops
6) Garden Tour
7) Do-It-Yourself Home Energy and Water Savings Toolkit 8) Garden Sense Consultation
These eight programs are already currently implemented by SMWSP.

6.2.2 Device and Financial Incentive-Based Conservation Programs Of the 60 device- and financial incentive-based water conservation programs included in the screening list, the Water Contractors identified the following three programs as high priority (average score of three or higher), with a preference for regional implementation through SMSWP, through pass-through grant funding:
1) Landscape Conversion or Turf Removal – SFR
2) Landscape Conversion or Turf Removal – MFR and CII
3) High Efficiency Clothes Washer Rebate – Residential
Agenda Item #8.1:

PUBLIC OUTREACH AND EDUCATION
Public Outreach through Print & Electronic
Media - Focused on Outdoor Irrigation 4.4 100% All X Irrigation School Education Programs 4.0 100% SFR,
MFR
XX All
Promote QWEL Training (Qualified Water
efficient Landscaper) 3.9 89% All X All Outdoor
Public Outreach through Print & Electronic
Media - Focused on Indoor Conservation 3.7 89% All X All Indoor Educational Workshops 3.3 78% All X All Outdoor
Garden Tour 3.2 78% SFR X All Outdoor
Garden Sense Consultation 3.1 78% SFR X All Outdoor
Do-It-Yourself Home Energy and Water Savings
Toolkit 3.2 78% SFR XX All

DEVICE-BASED AND FINANCIAL INCENTIVE

PROGRAMS
Landscape Conversion or Turf Removal - SFR 3.3 67% SFR X Irrigation Landscape Conversion or Turf Removal - MFR
and CII 3.2 67% MFR, CII X Irrigation
High Efficiency Clothes Washer Rebate -
Residential 3.1 67% SFR,
MFR
X
Clothes
Washer
Abbreviations:

AMI = advanced metering infrastructure MFR = multi-family residential CalWEP = California Water Efficiency Partnership MWELO = Model Water Efficient Landscape Ordinance CII = commercial, industrial, institutional PRV = pressure reducing valve COM = commercial SFR = single-family residential
HEU = High-Efficiency Urinals SMSWP = Sonoma-Marin Saving Water Partnership IRR = irrigation UHET = ultra high efficiency toilet
Notes:

Table 6-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
(a) Each Water Contractor was asked to rank each conservation program or measure in terms of priority as a regionally-administered program, where 5 indicated highest priority and 1 indicated the lowest priority. Results are presented as an average of the responses of all nine Water Contractors.

Preference
(b) Conservation Measure/Program
Current
SMSWP
Program
Primary End
Use
Indoor
Outdoor
Sector
(b) Presents the percentage of Water Contractors who indicated a priority of greater or equal to 3 for regional implementation.

Prioritization
(a)
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December 2025
Agenda Item #8.1:

Section 6 2025 Demand & Conservation Update
Conservation Measures Update City of Sonoma
22 December 2025
6-4 EKI C40180.00

6.2.3 Regional Program Screening Findings
During the May 2025 project workshop, the Water Contractors indicated that the three deviceand financial incentive- based programs identified under Section 6.2.2 are already being implemented at the local level and expressed a preference for them to continue to be implemented at a local level. The takeaway from this exercise is that the existing SMWSP public and education-based programs should remain regional programs and that there is currently no preference for new regional programs.

6.3 Screening of Conservation Measures for Local Implementation The local results of water conservation program prioritization screening were summarized for all Water Contractors individually, representing their local priorities and preferences. Appendix C presentsthe results for the City and shows (1) the average prioritization ranking for each program for local implementation, (2) the targeted sector, (3) whether the program targets indoor or outdoor savings; (4) the primary end use; and (5) the implementation status as a local program.

6.3.1 Agency Actions and Water Rate Conservation Programs Three agency action and water rate-based conservation programs were identified for the City as high priority (score of three or higher) for potential future implementation. These programs target water loss and irrigation by all customers. All these programs are currently implemented at the local level.

6.3.2 Public Outreach and Education Based Conservation Programs Three public outreach and education-based programs were identified as high priority (average score of three or higher) for potential future implementation. Of these programs, one would target outdoor water use, one would target indoor water use, and one would target both . All these programs are currently implemented at the local level.

6.3.3 Device and Financial Incentive Based Conservation Programs Three device- and financial incentive- based water conservation programs were identified as high priority (average score of three or higher) for potential future implementation, including one that would target indoor water use and two that would target outdoor water use . All these programs are currently implemented at the local level.

6.3.4 Policy and Regulation Based Conservation Programs The City identified three policy and regulation-based programs as high priority (average score of three or higher), including two that would target indoor water use and one that would target outdoor water use. The City currently implements one of these programs. The remaining two potential new programs identified are as follows, in general order of priority, with the first program (bolded) receiving a score of four:
1) Require Submetering for New MFR Developments
2) Require Submetering by Unit for New Commercial Developments Agenda Item #8.1:

Section 6 2025 Demand & Conservation Update
Conservation Measures Update City of Sonoma
22 December 2025
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6.4 Evaluation of Future Water Conservation Programs
Based on the conservation screening process described above, a suite of conservation programs to be considered for future implementation were evaluated. These programs were evaluated both individually and as components in three water conservation program scenarios, as shown in Table 6-2. The program scenarios each represent a potential approach or strategy for the City’s future conservation programs, specifically:
• Scenario A represents the City’s existing programs as a baseline, • Scenario B represents programs ranked most highly for local implementation by the City, and
• Scenario C focuses on programs that target outdoor water savings under Scenario B.

Table 6-2 also identifies the customer sectors each program would target as well as whether the program focuses on indoor or outdoor water use, or both.

The benefits and costs associated with implementation of these programs were evaluated using the AWE model, using a series of assumptions documented in Appendix B. Key assumptions and considerations related to the methodology used by the AWE model and in this analysis are provided below:
• Water savings assumptions were based on a combination of (1) AWE model default assumptions and (2) water savings factors developed based on other published literature sources.
• Costs to the utility were based on (1) rebate amounts of existing programs or (3) AWE model default assumptions.
• Utility benefit (i.e., avoided cost of water) is assumed to be $1,458/AF, consistent with the FY 2024-2025 cost of purchasing wholesale water from Sonoma Water. • Financial assumptions related to customer water rates were provided by the City. • Financial assumptions related to energy costs to the customer were assumed based on typical PG&E rates (PG&E, 2024).
• Assumed rate of program implementation was based on historical participation levels by City customers in similar programs.
• For purposes of near-term conservation program analysis, it is assumed that all programs are active from 2026 through 2030; water savings beyond this period reflect cumulative savings achieved over time from implementation during this five-year period. • Lost revenue due to reduced water sales is not included as a cost. • Additional program-specific considerations are provided as notes in the attached tables.

Table 6-3 presents a combination of individual water conservation measures, and identifies the following information for each program:
• Net present value of costs and benefits – represents the present value over the 25-year period discounted to current 2025 dollars.

Agenda Item #8.1:

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Conservation Measures Update City of Sonoma
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• Benefit to cost ratio – calculated as present value of costs divided by the present value of benefits.
• Water utility costs – costs that the City as a water utility will incur to operate the program including administrative costs.
• Customer costs – costs customers will incur to implement a program in the City’s service area.
• Utility benefits – the avoided cost to the City to produce the volume of water saved. • Customer benefits – the savings from reduced water/sewer utility bills and energy savings resulting from reduced use of hot water.
• Total water utility costs – includes costs to the City for program implementation from 2026-2030.
• Water savings in 2030 – one-year estimate water savings in 2030. • Water utility cost of water saved for individual programs – cost of water saved dividing by the lifetime water savings of that program.
• Water utility cost of water saved for program scenarios – weighted average of water utility cost of water saved for individual programs by the cumulative savings through 2050.

The analysis estimates active program savings based on the AWE model and does not include additional savings anticipated from passive savings (i.e., water savings associated with the natural replacement of less efficient water using fixtures and appliances due to both market shifts and increasing efficiency mandated by the building code and other regulatory requirements). Based on this analysis, and the assumptions presented in Appendix B, the benefit-cost ratios for the City range from 1.2 to 13.1. A benefit-cost ratio value greater than one indicates that the cost of implementing the program would be cheaper than purchasing supplies from Sonoma Water.

Table 6-4 presents the results of the analysis of the four conservation program scenarios identified in Table 6-3, and includes a summary of costs and benefits to the City and customers, estimated cumulative water savings through 2050 (based on assumed program implementation from 2026-2030), and the estimated cost of water saved to the City. Based on this, the City’s preferred water conservation measures for local implementation (i.e., Scenario B) have an estimated benefit-to-cost ratio at 1.5, similar to that of its existing programs (i.e., Scenario A) at

1.5, as the programs selected under each of the two scenarios are highly similar. In comparison, the benefit to cost ratio of outdoor programs (i.e., Scenario C) is 1.2. The projected cumulative water savings associated with implementation of locally preferred measures (i.e., Scenario B) is 41 AF by 2030 and 57 by 2050, at a cost of approximately $1,323/AF. The figure in shows active savings in 2030 associated with each scenario as well as anticipated passive savings.

Agenda Item #8.1:

Table 6-2 Conservation Program Scenarios
City of Sonoma, Sonoma-Marin Water Saving Partnership
(A) Baseline
(B) HighlyRanked Local
Programs
(C) HighlyRanked
Outdoor
Programs
AMI Leaks Notification Program All Both X X
HECW Rebate Program SFR Indoor X
Turf Rebate Program SFR, MFR, CII Outdoor X X X
High Efficiency Faucet Aerator / Showerhead
Giveaway - Residential Customers SFR, MFR Indoor X X
Abbreviations
AMI = advanced metering infrastructure MFR = Multi‐family residential CII = commercial, industrial, institutional SFR = Single-family residential HECW = High-efficiency clothes washer
Notes
Indoor/ Outdoor
Program Scenario (a)
(a) The program scenarios represent three potential approaches to program selection. Scenario 1 represents existing programs as a baseline, Scenario 2 represents programs prioritized for local implementation, and Scenario 3 focuses on outdoor water savings.

Program Sector
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Agenda Item #8.1:

Table 6-3 Costs and Savings of Potential Conservation Programs City of Sonoma, Sonoma-Marin Water Saving Partnership
Water
Utility Customers WaterUtility Customers WaterUtility Customers AMI Leaks Notification Program All Both $29,935 $74,507 $19,926 $109,595 1.5 0.7 $21,755 4.5 $971 SFR Indoor $3,906 $27,155 $570 $6,579 6.9 4.1 $715 0.2 $200 SFR,

MFR, CII
Outdoor $50,219 $94,519 $42,137 $388,955 1.2 0.2 $50,363 4.3 $1,177 SFR, MFR Indoor $14,897 $222,154 $1,139 $0 13.1 - $3,615 0.9 $250 Abbreviations
AFY = acre-feet per year MFR = multi‐family residential AMI = advanced metering infrastructur SFR = Single-family residential CII = Commercial, Industrial, and Institutional sq ft = square feet HECW = High-efficiency clothes washer $/AF = dollars per acre-foot Notes
(a)
(b) For purposes of near-term conservation program analysis, it is assumed that all programs are active from 2026 through 2030.

Program (a)
HECW Rebate Program
High Efficiency Faucet Aerator /
Showerhead Giveaway - Residential
Customers
Estimated water savings, benefits, and costs are calculated using the AWE model. Program savings, cost, and implementation rate assumptions used are presented in Appendix B.

Utility benefit (i.e., avoided cost of water) is assumed to be the cost of purchasing wholesale water from Sonoma Water. Customer benefit is assumed to be the variable cost of purchasing water from the utility (i.e., variable customer water rates).

Turf Rebate Program
Benefit to Cost Ratio Water Utility
Cost of Water
Saved ($/AF)
Water
Utility Costs
2026-2030 (b)
Water
Savings in
2030 (AFY)
Sector
Indoor/
Outdoor
Net Present Value of
Benefits Net Present Value of Cost
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Table 6-4 Comparison of Program Scenarios – Costs and Savings City of Sonoma, Sonoma-Marin Water Saving Partnership
Water
Utility Customers
Water
Utility Customers
Water
Utility Customers 2025 2030 2035 2040 2045
(A) Baseline $ 98,957 $ 418,335 $ 63,773 $ 505,129 1.6 0.8 10 16 43 55 58 61 $1,257 (B) Highly-Ranked Local Programs $ 95,051 $ 391,180 $ 63,202 $ 498,550 1.5 0.8 10 16 41 52 55 57 $1,323 (C) Highly-Ranked Outdoor Programs $ 50,219 $ 94,519 $ 42,137 $ 388,955 1.2 0.2 4 13 34 43 43 43 $1,177 Abbreviations
AF = acre-feet $/AF = dollars per acre-foot
Notes
(a)
(b) The water utility cost is based on the cumulative savings achieved through 2050 cumulative water savings.

Water Utility
Cost of Water
Saved ($/AF)
(b)
For purposes of near-term conservation program analysis, it is assumed that all programs are active from 2026 through 2030. Cumulative water savings achieved beyond 2030 reflect the ongoing benefit of program implementation.

Scenario (a)
Present Value of Benefits Present Value of Cost Benefit to Cost Ratio Cumulative Active Water Savings (AF) Water Savings
in 2030
(AFY)
61 61 61
10 10
4 0
10 20
30 40
50 60
70 80
(A) Baseline (B) Highly-Ranked Local Programs (C) Highly-Ranked Outdoor Programs Savings Potential (AFY)
Comparison of Program Scenarios - Savings in 2030
Passive Savings in 2030 Active Savings in 2030
Utility Unit Cost: $1,257/AF Utility Unit Cost: $1,323/AF Utility Unit Cost: $1,177/AF EKI C40180.00 6-9
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Section 7 2025 Demand & Conservation Update
Conclusions City of Sonoma
22 December 2025
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7 CONCLUSIONS
Although there have been no updates to the UWMP regulations since 2020, the MCCWL framework and related regulations will influence the 2025 UWMPs, as they will inform the water demand and conservation planning components. This project forecasted water demand through 2050 in accordance with CWC requirements and evaluated both historical and anticipated implementation of conservation programs.

7.1 Historical, Current, and Projected Water Demand
Water demand projections are developed consistent with CWC § 10631(d)(4)(A), which requires that “Water use projections, where available, shall display and account for the water savings estimated to result from adopted codes, standards, ordinances, or transportation and land use plans identified by the urban water supplier, as applicable to the service area.” The assumptions used as the bases for demand projections were developed in close coordination with the City and reflect a land-use based approach consistent with the City’s 2023-2031 Housing Element and ABAG and MTC’s Plan Bay Are 2050. It should be noted that all demand and conservation projections have limitations and should be considered estimates that require revisiting as factors that affect demands arise, such as economic or population shifts, extreme hydrological conditions, etc.

The methodology used to develop demand projections herein is also consistent with the CWC §10635(b)(4), requirement to consider climate change on projected demands. 6 The City’s per account water use declined significantly over the past 15 years as a result of the City’s conservation efforts and showed significant response to key events such as the 2014-2017 drought, the 2021-2023 drought, and the COVID-19 pandemic. The demand factors evaluated herein are based on water use during the 2017-2019 period, which assume a rebound in demand following the recent drought and represent a higher level of demand compared to current levels.

Thus, the periods used to develop the demand projections reflect conditions representative of the hotter, drier weather expected as a result of climate change.

Although MCCWL Objective water use standards are expected to become more stringent over time, the City is projected to comply with its Objectives through 2035 based on forecasted population and baseline water use, but in 2040 the City’s water use is anticipated to be slightly (i.e., 1%) above its Objective. It should be noted that this forecast is conducted prior to accounting for active conservation savings.

7.2 Conservation Measures Participation, Savings, and Update Participation data indicate that the City’s conservation programs, including the HECW Rebate, turf replacement, and HET Rebate Programs have been successful in achieving water savings 6 CWC §10635(b)(4) requires that suppliers consider plausible changes on projected supplies and demands under climate change conditions specific to their five-year drought risk assessments. Section 4.5 of the draft 2020 UWMP Guidebook more generally recommends that consideration of climate change be incorporated into all demand projections.

Agenda Item #8.1:

Section 7 2025 Demand & Conservation Update
Conclusions City of Sonoma
22 December 2025
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between 2010 and 2024. Most programs have a lower adoption rate over the recent five years compared to historical rates, with higher popularity observed during drought periods.

A benefit-cost analysis of future program scenarios shows that all options yield a benefit-to-cost ratio at or greater than one, meaning program implementation is more cost-effective than purchasing additional water supplies from Sonoma Water. The preferred program portfolio achieves an estimated benefit-to-cost ratio of 1.5, while its existing programs are at 1.6.

Agenda Item #8.1:

Section 8 2025 Demand & Conservation Update
References City of Sonoma
22 December 2025
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8 REFERENCES
ABAG, 2021. Plan Bay Area 2050. Association of Bay Area Governments and Metropolitan Transportation Commission, October 2021.

AWE, 2021. “Water Conservation Tracking Tool - Version 4.0.” Alliance for Water Efficiency (AWE), 2021. https://www.allianceforwaterefficiency.org/resources/tools/waterconservation-tracking-tool.

DOF, 2024a. E-4 Population Estimates for Cities, Counties, and the State, 2021-2024, with 2020 Census Bookmark. State of California, Department of Finance (DOF), May 2024.

EKI, 2021. 2020 Urban Water Management Plan Prepared for City of Sonoma. EKI Environment & Water, Inc., June 2021.

PG&E, 2024. Pacific Gas and Electric (PG&E) Electric Rate Advisory, effective 1 March 2024.

Pacific Gas and Electric, 2024.

Sonoma, 2023. City of Sonoma 6th Cycle Housing Element 2023-2031, adopted on 31 January 2023.

U.S. Census Bureau, 2025. Longitudinal Employer-Household Dynamics (LEHD) Origin-Destination Employment Statistics, 2010-2022. United States Census Bureau, accessed 10 April 2025.

Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma

APPENDIX A
Methodology for Estimating Indoor and Outdoor Water Use Agenda Item #8.1:

Appendix A 2025 Demand & Conservation Update
Methodology for Estimating Indoor and Outdoor Water Use City of Sonoma A-1
December 2025
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Methodology for Estimating Indoor and Outdoor Water Use This appendix documents the methodology used in Section 3.3 of the 2025 Water Demand and Conservation Measure Update for the nine participating members of the Sonoma-Marin Saving Water Partnership (Water Contractors) prepared by EKI Environment & Water (EKI).

For customer accounts without dedicated irrigation meters, the amount of water used indoors versus outdoors is not directly measured and must be estimated. Traditionally, indoor and outdoor water use has been estimated using the “minimum winter month” method, which assumes that water use during the lowest-demand winter month is entirely attributable to indoor consumption. However, winter irrigation is common in California and this assumption tends to overestimate indoor water use.

EKI has developed the method below to estimate water use for meters with mixed indoor and outdoor water use (i.e. mixed-use meters, or MUMs) using an annual irrigation scaling factor developed based on data collected from dedicated irrigation meters. This method is consistent with the “Seasonal Adjustment Method” utilized in the Department of Water Resources’ residential indoor water use study to inform water use efficiency standards as part of the Making Conservation a California Way of Life Legislation (DWR, 2021).
1 DATA SOURCES
The analysis is based on potable water consumption data covering calendar year 2024. While multi-year water consumption data are available, indoor and outdoor use estimates were derived from the most recent complete calendar year (2024) to reflect current usage and seasonal patterns.

The dataset was parsed for the analysis herein and includes the following fields:
• Year and Month – Derived from service period or billing date. • Sector Group – Consolidated customer sectors, including Single Family, Multi-family, Commercial/Industrial/Institutional (CII Total), and Irrigation. • Consumption – Monthly water use converted to acre-feet. • Water Type – Only potable water use was included in the analysis.

Potable irrigation accounts were used to infer the seasonal profile of outdoor water use. Estimates of indoor and outdoor use were produced for sector groups where both types of use are present (e.g., Single Family, Multi-family, CII Total).
2 METHODOLOGY
This section describes the method used to estimate the indoor and outdoor components of total annual water use for each sector group.

2.1 Step 1: Identify Analysis Year
The most recent year with complete monthly data (2024) was selected to represent current conditions and ensure seasonal variation is captured accurately.

2.2 Step 2: Calculate Seasonal Scaling Factor
Potable dedicated irrigation meters (DIMs) were assumed to represent purely outdoor water use.

Monthly water use in the most recent year (2024) was aggregated for all irrigation accounts (i.e. accounts on DIMs), and a seasonal scaling factor (SF) was calculated as:

Agenda Item #8.1:

Appendix A 2025 Demand & Conservation Update
Methodology for Estimating Indoor and Outdoor Water Use City of Sonoma A-2
𝑆𝑐𝑎𝑙𝑖𝑛𝑔 𝐹𝑎𝑐𝑡𝑜𝑟 (𝑆𝐹) =
𝑀𝑎𝑥 (𝑚𝑜𝑛𝑡ℎ𝑙𝑦 𝑢𝑠𝑒)
𝑀𝑖𝑛 (𝑚𝑜𝑛𝑡ℎ𝑙𝑦 𝑢𝑠𝑒)
This metric reflects the ratio between peak summer irrigation and baseline winter irrigation, which is assumed to persist year-round at a reduced level. The metric also reflects the local conditions and climatic conditions during 2024. As shown on Figure 2-1, the variations in monthly water use from DIMs generally follow a consistent pattern: highest water use in the summer months and early fall (July through September), lowest water use in the winter month and early spring (January through March).

Figure 2-1 Example Irrigation Outdoor Use by DIMs Used to Calculate Scaling Factor

2.3 Step 3: Filter Target Sector Groups
The analysis focuses on three sector groups on MUMs expected to include both indoor and outdoor use:
• Single Family
• Multi-family
• CII Total
Only potable water demand from MUMs is considered.

2.4 Step 4: Extract Seasonal and Annual Demand
Monthly potable water demand by MUMs was aggregated by sector group. The representative lowirrigation month (winter) is selected by finding the minimum water use across the months of January, February, and March. Similarly, the high-irrigation month (summer) is selected by finding the maximum December 2025
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Appendix A 2025 Demand & Conservation Update
Methodology for Estimating Indoor and Outdoor Water Use City of Sonoma A-3
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water use from the months of July, August, and September. Total annual demand was also computed for each sector group.

2.5 Step 5: Estimate Indoor and Outdoor Use
The SF calculated under Step 2 are used to estimate the proportion of water used for irrigation purposes by MUMs. This method assumes that indoor water use is generally consistent over the course of the year and that customers within the Water Contractor’s service area experience similar irrigation patterns. This assumption tends to hold more strongly for residential customers. However, for CII customers, although some use water through MUMs for outdoor irrigation, they may also have seasonally variable indoor demands, such as cooling towers. As a result, this method may underestimate indoor use and overestimate outdoor use in service areas with significant CII cooling demands.

Figure 2-2 illustrates the annual water use pattern and the components of the equations below used to derive estimated indoor and outdoor water use for sectors with MUMs.

Figure 2-2 Indoor and Outdoor Separation Methodology for Water Use on MUMs Indoor use was estimated as the month with the least water use in January, February, or March, adjusted to remove residual winter irrigation using the SF.

Winter irrigation is estimated as:

𝑆𝐹 =
𝑊 + (𝑀𝑎𝑥 − 𝑀𝑖𝑛)
𝑊
= 1 +
𝑀𝑎𝑥 − 𝑀𝑖𝑛
𝑊
⇒ 𝑊 =
𝑀𝑎𝑥 − 𝑀𝑖𝑛
𝑆𝐹 − 1
Agenda Item #8.1:

Appendix A 2025 Demand & Conservation Update
Methodology for Estimating Indoor and Outdoor Water Use City of Sonoma A-4
December 2025
EKI C40180.00
Where:
• W = Outdoor winter irrigation during the lowest water use month • Max = Max monthly use in one of July, August, or September • Min = Min monthly use in January, February, or March
• SF = Scaling factor
Indoor monthly use is then:

𝐼 = 𝑀𝑖𝑛 − 𝑊
Indoor annual use is computed as:

𝐼 × 12
Outdoor annual use is then the residual between total annual use and indoor annual use:

𝑂𝑢𝑡𝑑𝑜𝑜𝑟 𝐴𝑛𝑛𝑢𝑎𝑙 𝑈𝑠𝑒 = 𝑇𝑜𝑡𝑎𝑙 𝐴𝑛𝑛𝑢𝑎𝑙 𝑈𝑠𝑒 − 𝐼𝑛𝑑𝑜𝑜𝑟 𝐴𝑛𝑛𝑢𝑎𝑙 𝑈𝑠𝑒 3 ASSUMPTIONS AND LIMITATIONS
• DIMs reflect purely outdoor use, with consistent year-round patterns across groups. • Low point of outdoor irrigation happens in one of January, February, or March; similarly peak summer irrigation happens in one of July, August, or September. • Indoor water use is assumed to be consistent throughout the year. • Customers within each sector group are assumed to exhibit similar usage patterns. • The scaling factor derived from DIMs is representative of outdoor demand across all MUMs, which is a stronger assumption for residential customers but less so for CII customers due to seasonal cooling demands.
4 REFERENCES
DWR, 2021. Recommendations for urban water use efficiency standards, variances, performance measures, and annual water use reporting (Report No. WUES-DWR-2021-01A). California Department of Water Resources. Available at: https://water.ca.gov/-/media/DWR-Website/WebPages/Programs/Water-Use-And-Efficiency/2018-Water-Conservation-Legislation/PerformanceMeasures/UWUE_STD_VAR_PM_REPORT_WUES-DWR-2021-01A_COMPLETE.pdf Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma

APPENDIX B
Conservation Program Assumptions
Agenda Item #8.1:

Table B-1 Conservation Program Savings Assumptions
City of Sonoma, Sonoma-Marin Saving Water Partnership
Agency Program Name Units
Savings
Assumption
(gpd/unit)
Life of
Savings
(Years)
Decay Rate
(%/Yr)
Free Riders
(% activity) Source(s)
HECW Rebate Program Washer 19.3 15 0% 0% AWE Tool Conservation Program Library.

Turf Rebate Program Square Feet 0.1 10 0% 0% AWE Tool Conservation Program Library.

High Efficiency Faucet Aerator / Showerhead
Giveaway - Residential Customers Showerhead 2.4 10 0% 0% AWE Tool Conservation Program Library.

AMI Leak Notifications Program (SFR) AMI Meter 0.7 1 0% 0% AWE Tool Conservation Program Library.

AMI Leak Notifications Program (MFR, CII, IRR) AMI Meter 2.0 1 0% 0% AWE Tool Conservation Program Library.

Abbreviations
AMI = advanced metering infrastructure HECW = high-efficiency clothes washer AWE = Alliance for Water Efficiency Water Conservat IRR = Irrigation CII = commercial, industrial, institutional MFR = multi-family residential gpd = gallons per day SFR = single-family residential
References

1. AWE, 2021. Water Conservation Tracking Tool. Version 4.0. Alliance for Water Efficiency.

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Agenda Item #8.1:

Table B-2 Conservation Program Cost Assumptions
City of Sonoma, Sonoma-Marin Saving Water Partnership
Agency Program Name Units Utility Cost
per Unit (a)
Customer
Cost per Unit Source(s)
HECW Rebate Program Washer $65 $750 Utility cost based on City's rebate amount. Customer cost based on cost of a low-end ENERGY STAR residential washer model.

Turf Rebate Program Square Feet $1.3 $12 Utility cost based on City's rebate amount. Customer cost from Marin Municipal Water District's SWSA modeling.

High Efficiency Faucet Aerator / Showerhead
Giveaway - Residential Customers Showerhead $10 $0 Utility cost from AWE Tool Conservation Program Library. Assumes no customer cost.

AMI Leak Notifications Program (SFR) AMI Meter $1 $5.5 Utility cost from AWE Tool Conservation Program Library.

Customer costs based on Note (b).

AMI Leak Notifications Program (MFR, CII, IRR) AMI Meter $1 $5.5 Similar to SFR AMI Leak Notifications Program.

Abbreviations
AMI = advanced metering infrastructure HECW = high-efficiency clothes washer AWE = Alliance for Water Efficiency Water Conservation Tracking Tool IRR = Irrigation CII = commercial, industrial, institutional MFR = multi-family residential gpd = gallons per day SFR = single-family residential
Notes
(a) Utility cost for rebate programs includes a 30% administrative cost in addition to the City's rebate amount.

References

1. AWE, 2021. Water Conservation Tracking Tool. Version 4.0. Alliance for Water Efficiency. (b) An average household leak is estimated to be 180 gallons per week per Reference 3. It is assumed that fixing such leak costs $200, averaged across the entire customer base with AMI.

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Agenda Item #8.1:

Table B-3 Conservation Program Implementation Rate Assumptions City of Sonoma, Sonoma-Marin Saving Water Partnership
Agency Program Name Units Implementation
Rate
Unit Source(s)
HECW Rebate Program Washer 2.2 Washer / Year Based on past program participation rates from 2020–2024.

Turf Rebate Program Square Feet 7,748 Square Feet /
Year
Based on past program participation rates
from 2020–2024.

High Efficiency Faucet Aerator /
Showerhead Giveaway - Residential
Customers
Showerhead 72 Showerhead /
Year
Assume 1% of SFR customers will
participate. Assumes 2 showerheads per
account.

AMI Leak Notifications Program (SFR) AMI Meter 3,616 AMI Meter / Year
Based on total number of meters.

AMI Leak Notifications Program (MFR, CII,
IRR) AMI Meter 745 AMI Meter / Year
Based on total number of meters.

Abbreviations
AMI = advanced metering infrastructure HECW = high-efficiency clothes washer AWE = Alliance for Water Efficiency Water Conservation Tracking Tool IRR = Irrigation CII = commercial, industrial, institutional MFR = multi-family residential gpd = gallons per day SFR = single-family residential
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Agenda Item #8.1:

2025 Demand & Conservation Update
City of Sonoma

APPENDIX C
Prioritization and Screening of Future Water Conservation Measures Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local

AGENCY ACTIONS AND WATER RATES
Increase Enforcement of Customer Pressure Reducing Valve (PRV) Requirement 1.5 1.6 25% 25%
Increase Enforcement of Indoor Fixture Retrofit at Time of Sale 1.7 2.4 33% 56% Increase Enforcement of State Water Waste Regulations 2.0 2.6 38% 63% Rate Structure Evaluation 2.0 2.0 25% 50%
Regional UHET and/or Urinal Bulk Purchase Program 1.3 1.1 11% 0% Water Budgeting/Monitoring for Large Landscape Accounts 1.8 2.9 33% 67% Establish Separate Pricing Structure for Irrigation Accounts 1.4 2.7 13% 50% Implementation or Modification of Tiered Water Rates
(Conservation Pricing) 2.4 3.3 38% 75%
Water Budget Based Billing for All Customers 1.3 1.9 11% 33% Water Budget Based Billing for Only Irrigation Customers 1.7 2.9 22% 56% Install AMI for Existing Accounts 2.6 4.3 25% 88%
Install AMI for High Water Users and Large Landscape Accounts 2.8 4.4 50% 88% Install AMI in New Development 2.4 4.3 38% 88%
End Point Leak Detection and Flow Monitoring 2.1 3.0 25% 50% CalWEP District Distribution Program 1.8 2.3 33% 33%
Behavior Based Customer Messaging Platforms 1.9 2.9 25% 63% Average by Program Type 1.9 2.8

PUBLIC OUTREACH AND EDUCATION
Water Use Surveys/Audits - CII 2.3 2.9 44% 56%
Water Use Surveys/Audits - MFR 2.7 3.1 67% 67%
Water Use Surveys/Audits - SFR 2.6 3.0 67% 67%
Garden Sense Consultation 3.1 2.3 78% 56%
Educational Workshops 3.3 2.7 78% 56%
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)
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Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)
Garden Tour 3.2 1.6 78% 11%
SFR Home Water Report 2.0 2.8 44% 67%
Promote Green Building and Certification 2.4 1.3 56% 11% Provide Support with Smart Irrigation Controller Setup 2.7 2.6 67% 56% Public Outreach through Print & Electronic Media - Focused on Indoor Conservation 3.7 3.4 89% 89%
Public Outreach through Print & Electronic Media - Focused on Outdoor Irrigation 4.4 4.1 100% 89%
Promote QWEL Training (Qualified Water efficient Landscaper) 3.9 2.6 89% 33% School Education Programs 4.0 2.6 100% 67%
Do-It-Yourself Home Energy and Water Savings Toolkit 3.2 2.2 78% 44% Average by Program Type 3.1 2.7

DEVICE-BASED AND FINANCIAL INCENTIVE PROGRAMS
High Efficiency Faucet Aerator / Showerhead Giveaway - CII Customers 2.4 3.1 44% 56%
High Efficiency Faucet Aerator / Showerhead Giveaway -
Residential Customers 2.7 4.0 56% 89%
Toilet Flapper Giveaway - Residential and CII 2.2 3.0 44% 67% UHET Direct Installation - Residential and CII 1.7 2.2 33% 33% Urinal Direct Installation - CII 1.7 2.0 44% 33%
Thermostatic Shut-Off Valve Showerheads/Tub Spouts Rebates 1.7 1.8 33% 33% HET (<1.28 gal/flush) Replacement Rebates 2.3 2.6 44% 44% High Efficiency Urinal (<0.25 gal/flush) Replacement Rebates - CII 2.1 2.6 44% 44% Plumber Initiated UHET and / or HEU Retrofit Program 1.7 2.0 22% 22% Direct Install of Efficient Indoor Fixtures - Commercial and Industrial 1.9 2.4 33% 44%
Direct Install of Efficient Indoor Fixtures - Government Buildings 2.1 2.4 44% 44% Direct Install of Efficient Indoor Fixtures - Low Income Residential 2.3 2.9 44% 56% Direct Install of Efficient Indoor Fixtures - Residential 2.3 2.7 44% 44% C-2 EKI C40180.00
Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)
High Efficiency Clothes Washer Install - Low Income Residential Customers 1.6 1.2 22% 11%
High Efficiency Clothes Washer Rebate - Residential 3.1 3.1 67% 67% High Efficiency Clothes Washer Rebate Program - CII 2.0 2.8 44% 78% Efficient Dishwasher Rebates 1.9 1.9 44% 44%
Indoor Fixture Program For Hotels & Motels 2.0 2.8 44% 67% Indoor Fixture Program For Schools 2.1 2.0 44% 33%
Water Savings Incentive Program for CII 1.8 2.9 33% 78% Nonresidential Incentive for Self-closing or Metering Faucets 1.9 2.6 22% 44% Laminar Flow Restrictor Rebate for Health Care Related Facilities 1.9 2.8 22% 67% Autoclave (Steam-Sterilizer) Retrofit Rebates 1.3 1.4 11% 22% Air Cooled Ice Machine Rebates 1.7 1.9 22% 44%
Connectionless Food Steamer Rebates 2.0 1.9 33% 44%
Commercial Kitchen High Efficiency Dishwasher Rebate 1.3 1.8 11% 33% Dipper Well Rebates 2.2 2.3 44% 67%
Hot Water on Demand Pump System Rebate/ Hot Water
Recircling System 1.7 2.2 33% 56%
Dry Vacuum Pumps 1.3 1.9 11% 44%
Ozone Laundry Washer Rebate - CII 1.6 2.1 22% 56%
Plumbing Flow Control Valve - CII (Faucets and Showerheads) 1.9 2.7 22% 56% Incentivize Cooling Tower Upgrades 1.3 2.1 11% 56%
Rebates for Conductivity Controllers on Cooling Towers 1.6 2.1 22% 56% Sustained Reduction, or rebates for any CII project which demonstrates water savings 1.6 2.0 22% 33%
Landscape Conversion or Turf Removal - MFR and CII 3.2 4.7 67% 100% Landscape Conversion or Turf Removal - SFR 3.3 4.8 67% 100% Mulch Rebate 2.4 3.4 44% 67%
C-3 EKI C40180.00
Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)
Incentivize Irrigation Equipment Upgrades - SFR 2.0 3.4 33% 67% Commerical Landscape Irrigation Improvement Program (CLIIP) Rebates 2.4 3.5 50% 75%
Rotating Sprinkler Nozzle Giveaway 2.4 2.8 56% 56%
Nozzle Replacement Irrigation - Residential 1.9 2.9 33% 44% Nozzle Replacement Irrigation CII - Large Landscape 1.9 3.0 33% 56% In-Stem Flow Regulators 1.9 2.1 33% 33%
Smart Irrigation Controller (Weather-Based Irrigation Controller) Giveaway - Large Landscape 1.9 2.3 44% 44%
Smart Irrigation Controller (Weather-Based Irrigation Controller) Giveaway - SFR 1.9 2.7 44% 44%
Soil Moisture Sensor Giveaway 2.0 2.1 44% 22%
Soil Moisture Sensor Rebate 1.9 2.0 44% 22%
Pilot Spring Irrigation Repairs Rebate 2.0 2.2 44% 33%
Rain Barrel Rebate 2.2 3.1 44% 67%
Rain Barrel Rebate - MFR & Large Landscapes 2.0 2.9 33% 56% Incentivize Gray Water Retrofit for Existing SFR Customers 1.9 2.7 22% 56% Incentivize Gray Water Systems for New CII Development 1.8 1.9 22% 33% Incentivize Submetering for Existing Customers - MFR, CII 1.7 2.4 33% 56% Incentivize Submetering of Cooling Towers for Existing Customers 1.1 1.9 0% 33% Flow Sensor Rebate Irrigation System 1.7 2.3 33% 44%
SFR Wireless Flow Monitor 1.7 2.0 33% 33%
Incentivize Replacement of Pressure Reducing Valves (PRVs) with 60-70 psi PRVs 1.4 1.7 11% 22%
Pool Removal Rebates 1.8 2.6 22% 44%
Swimming Pool and Hot Tub Cover Rebates 1.6 2.7 33% 56% Tiered Water Rate Exemption Assitance Program 1.0 1.4 0% 11% Average by Program Type 1.9 2.5
C-4 EKI C40180.00
Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)

POLICIES AND REGULATIONS
Demand Offset/Water Neutral Policy for Large New
Developments 2.7 3.7 44% 78%
Prohibit Once through Cooling Systems 2.7 3.9 44% 78%
Require <0.25 gal/flush Urinals in New Development 1.6 1.9 22% 33% Require <1.0 gal/flush Toilets in New Development 2.1 3.1 33% 56% Require Cooling Tower Retrofits 2.2 2.6 44% 56%
Require High Efficiency Clothes Washers in New Development 1.7 2.6 22% 44% Require Hot Water on Demand / Structured Plumbing in New Residential Development 2.0 2.4 44% 56%
Require Irrigation Designers / Installers be Certified (QWEL) 1.6 1.9 22% 33% Require On-Site Water Reuse Systems (Grey Water or Black Water) for Large CII Developments 1.8 1.9 33% 33%
Require Plumbing for Gray Water in New SFR Development 2.2 1.9 33% 33% Require Plumbing for Recycled Water in New CII Development 1.6 3.0 11% 56% Require Plumbing for Recycled Water in New MFR Development 1.8 2.3 33% 33% Require Rain Barrels in New Development 1.8 2.0 33% 44% Require Submetering by Unit for Existing Commercial Customers 1.8 2.1 33% 44% Require Submetering by Unit for New Commercial Developments 1.6 2.8 22% 67% Require Submetering for New MFR Developments 2.1 2.4 44% 44% Require Submetering for New Mobile Home Park Developments 2.2 2.1 33% 44% Require Submetering of Cooling Towers for Existing Customers 1.8 2.3 22% 33% Require Submetering of Cooling Towers for New Development 1.1 2.1 0% 33% Require Submetering of Existing MFR (and Mobile Home Park) Customers 1.3 1.7 11% 22%
Require Submetering of Landscaping for Existing MFR and Commercial Customers 1.3 2.0 11% 33%
Require Submetering of Landscaping for New MFR and
Commercial Developments 1.8 2.8 11% 44%
Require Swimming Pool and Hot Tub Covers 1.6 2.4 11% 33% C-5 EKI C40180.00
Agenda Item #8.1:

Table C-1 Regional Prioritization of Conservation Measures and Programs Sonoma-Marin Saving Water Partnership
Regional Local Regional Local
Conservation Measure/Program
Current
SMSWP
Program
Prioritization (a) Preference (b)
Require Water Efficiency Plan Reviews for New CII Development 1.8 2.8 22% 56% Require Weather Adjusting Smart Irrigation Controllers, Rain Sensors, and/or Soil Moisture Sensors in New Development 1.8 3.1 22% 56% Restrict Landscape Irrigation to Designated Days/Times 1.3 2.1 11% 33% Water Conserving Landscape and Irrigation Codes, More
Stringent than MWELO 2.2 3.6 33% 67%
Water Waste Ordinance 2.7 4.2 33% 78%
Average by Program Type 1.9 2.6
Abbreviations:

AMI = advanced metering infrastructure MFR = multi-family residential CalWEP = California Water Efficiency Partnership MWELO = Model Water Efficient Landscape Ordinance CII = commercial, industrial, institutional PRV = pressure reducing valve COM = commercial SFR = single-family residential
HEU = High-Efficiency Urinals SMSWP = Sonoma-Marin Saving Water Partnership IRR = irrigation UHET = ultra high efficiency toilet
Notes:
(a) Each Water Contractor was asked to rank each conservation program or measure in terms of priority as a regionally-administered program, and as a locally administered program, where 5 indicated highest priority and 1 indicated the lowest priority. Results are presented as an average of the responses of all nine Water Contractors. (b) Presents the percentage of Water Contractors who indicated a priority of greater or equal to 3 for regional or local implementation.

C-6 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program

AGENCY ACTIONS AND WATER RATES
Increase Enforcement of Customer Pressure
Reducing Valve (PRV) Requirement 1 All XX Water loss;
Irrigation
Yes,
previously
Increase Enforcement of Indoor Fixture Retrofit at
Time of Sale 1 All XX
Toilet, Urinal,
Faucet,
Showerhead
No
Increase Enforcement of State Water Waste
Regulations 1 All X Irrigation No
Install AMI for Existing Accounts 5 All XX Water loss;
Irrigation Yes, currently
Regional UHET and/or Urinal Bulk Purchase Program 1 All X Toilet / Urinal No Water Budgeting/Monitoring for Large Landscape
Accounts 1 IRR XX Irrigation Yes,
previously
Establish Separate Pricing Structure for Irrigation
Accounts 1 IRR X Irrigation No
Implementation or Modification of Tiered Water
Rates (Conservation Pricing) 1 All XX All No
Water Budget Based Billing for All Customers 1 All XX All No Water Budget Based Billing for Only Irrigation
Customers 1 CII, IRR X Irrigation No
Install AMI for High Water Users and Large
Landscape Accounts 4 All X Water loss;
Irrigation Yes, currently
Install AMI in New Development 3 All XX Water loss;
Irrigation Yes, currently
End Point Leak Detection and Flow Monitoring 2 All XX Water loss; Irrigation Yes, currently
Rate Structure Evaluation 1 All XX All Yes, currently
CalWEP District Distribution Program 1 SFR, MFR,
COM
XX All Yes, currently
Behavior Based Customer Messaging Platforms 1 All XX All No

PUBLIC OUTREACH AND EDUCATION
Water Use Surveys/Audits - CII 1 CII XX All Yes, currently Water Use Surveys/Audits - MFR 1 MFR X All Yes, currently Water Use Surveys/Audits - SFR 1 SFR XX All Yes,
previously
Garden Sense Consultation 1 SFR X All Outdoor Yes, currently Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
C-7 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program
Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
Educational Workshops 1 All X All Outdoor Yes,
previously
Garden Tour 1 SFR X All Outdoor Yes, currently
SFR Home Water Report 1 SFR XX All No
Promote Green Building and Certification 1 CII XX All No Provide Support with Smart Irrigation Controller
Setup 1 All X Irrigation No
Public Outreach through Print & Electronic Media -
Focused on Outdoor Irrigation 5 All X Irrigation Yes, currently Public Outreach through Print & Electronic Media -
Focused on Indoor Conservation 4 All X All Indoor Yes, currently Promote QWEL Training (Qualified Water efficient
Landscaper) 2 All X All Outdoor Yes, currently
School Education Programs 3 SFR, MFR XX All Yes, currently

DEVICE-BASED AND FINANCIAL INCENTIVE

PROGRAMS
Landscape Conversion or Turf Removal - SFR 5 SFR X Irrigation Yes, currently Landscape Conversion or Turf Removal - MFR and
CII 4 MFR, CII X Irrigation Yes, currently
Toilet Flapper Giveaway - Residential and CII 1 All X Toilet No UHET Direct Installation - Residential and CII 1 CII X Toilet No Urinal Direct Installation - CII 1 CII X Urinal No
Thermostatic Shut-Off Valve Showerheads/Tub
Spouts Rebates 1 SFR, MFR, CII X Shower No
HET (<1.28 gal/flush) Replacement Rebates 1 SFR, MFR X Toliet Yes, previously
High Efficiency Urinal (<0.25 gal/flush) Replacement
Rebates - CII 1 CII X Urinal No
Plumber Initiated UHET and / or HEU Retrofit
Program 1 All X Toilet / Urinal No
Direct Install of Efficient Indoor Fixtures -
Commercial and Industrial 1 CII X
Toilet, Urinal,
Faucet,
Showerhead
No
Direct Install of Efficient Indoor Fixtures -
Government Buildings 1 CII X
Toilet, Urinal,
Faucet,
Showerhead
No
C-8 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program
Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
Direct Install of Efficient Indoor Fixtures - Low
Income Residential 1 SFR, MFR X Toilet, Faucet,
Showerhead No
Direct Install of Efficient Indoor Fixtures - Residential 1 SFR, MFR X Toilet, Faucet, Showerhead No
Do-It-Yourself Home Energy and Water Savings
Toolkit 1 SFR XX All Yes, currently
High Efficiency Clothes Washer Install - Low Income
Residential Customers 1 SFR, MFR X Clothes Washer No
High Efficiency Clothes Washer Rebate - Residential 1 SFR, MFR X Clothes Washer Yes, currently High Efficiency Clothes Washer Rebate Program - CII 1 CII X Clothes Washer No High Efficiency Faucet Aerator / Showerhead
Giveaway - Residential Customers 3 SFR, MFR X Faucet,
Showerhead Yes, currently
Indoor Fixture Program For Hotels & Motels 1 CII X All Indoor No Indoor Fixture Program For Schools 1 CII X All Indoor No Water Savings Incentive Program for CII 1 CII X All Indoor No Nonresidential Incentive for Self-closing or Metering
Faucets 2 CII X Faucet No
Laminar Flow Restrictor Rebate for Health Care
Related Facilities 1 Institutional X Faucet No
Autoclave (Steam-Sterilizer) Retrofit Rebates 1 CII X CII Equipment No Air Cooled Ice Machine Rebates 1 CII X CII Equipment No Connectionless Food Steamer Rebates 1 CII X CII Equipment No Commercial Kitchen High Efficiency Dishwasher
Rebate 1 Commercial X Dishwashers No
Dipper Well Rebates 1 CII X CII Equipment No
Hot Water on Demand Pump System Rebate/ Hot
Water Recircling System 1 SFR, MFR X Hot Water No
Dry Vacuum Pumps 1 CII X CII Equipment No
Ozone Laundry Washer Rebate - CII 1 CII X Clothes Washer No Plumbing Flow Control Valve - CII (Faucets and
Showerheads) 1 Commercial X Faucet No
Incentivize Cooling Tower Upgrades 1 CII X Cooling Towers No C-9 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program
Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
Rebates for Conductivity Controllers on Cooling
Towers 1 CII X Cooling Towers No
Sustained Reduction, or rebates for any CII project
which demonstrates water savings 1 CII XX All No
High Efficiency Faucet Aerator / Showerhead
Giveaway - CII Customers 1 CII X Faucet,
Showerhead Yes, currently
Efficient Dishwasher Rebates 1 SFR X Dishwashers Yes, currently Mulch Rebate 1 SFR X Irrigation No
Incentivize Irrigation Equipment Upgrades - SFR 1 SFR X Irrigation No Commerical Landscape Irrigation Improvement
Program (CLIIP) Rebates 1 Commercial X Irrigation No
Rotating Sprinkler Nozzle Giveaway 1 All X Irrigation Yes, currently Nozzle Replacement Irrigation - Residential 1 SFR, MFR X Irrigation No Nozzle Replacement Irrigation CII - Large Landscape 1 CII X Irrigation No In-Stem Flow Regulators 1 Commercial X Irrigation No
Smart Irrigation Controller (Weather-Based
Irrigation Controller) Giveaway - Large Landscape 1 MFR, CII X Irrigation No Smart Irrigation Controller (Weather-Based
Irrigation Controller) Giveaway - SFR 1 SFR X Irrigation No Soil Moisture Sensor Giveaway 1 All X Irrigation No
Soil Moisture Sensor Rebate 1 All X Irrigation No
Pilot Spring Irrigation Repairs Rebate 1 MFR, COM,
IRR
X Irrigation No
Rain Barrel Rebate 1 SFR X Irrigation No
Rain Barrel Rebate - MFR & Large Landscapes 1 MFR, CII X Irrigation No Incentivize Gray Water Retrofit for Existing SFR
Customers 1 SFR X Irrigation / Gray
Water
No
Incentivize Gray Water Systems for New CII
Development 1 CII X Irrigation / Gray
Water
No
Incentivize Submetering for Existing Customers -
MFR, CII 1 MFR, COM,
IRR
X All Indoor No
Incentivize Submetering of Cooling Towers for
Existing Customers 1 CII X Cooling Towers No
C-10 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program
Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
Flow Sensor Rebate Irrigation System 1 SFR, MFR X Irrigation No SFR Wireless Flow Monitor 1 SFR XX Water Loss No
Incentivize Replacement of Pressure Reducing
Valves (PRVs) with 60-70 psi PRVs 1 All XX Water loss;
Irrigation No
Pool Removal Rebates 1 SFR, MFR X Pool/Hot Tub No
Swimming Pool and Hot Tub Cover Rebates 1 SFR, MFR X Pool/Hot Tub No Tiered Water Rate Exemption Assitance Program 1 SFR XX
Toilet, Faucet,
Showerhead,
Clothes Washer,
Irrigation
No

POLICIES AND REGULATIONS
Demand Offset/Water Neutral Policy for Large New
Developments 1 All XX All No
Prohibit Once through Cooling Systems 1 CII XX CII Equipment No Require <0.25 gal/flush Urinals in New Development 1 CII X Urinal No Require <1.0 gal/flush Toilets in New Development 2 All X Toilet No Require Cooling Tower Retrofits 1 CII X Cooling Towers No Require High Efficiency Clothes Washers in New
Development 1 SFR, MFR X Clothes Washer No
Require Hot Water on Demand / Structured
Plumbing in New Residential Development 1 SFR, MFR X Shower/Sink No Require Irrigation Designers / Installers be Certified
(QWEL) 1 All X Irrigation No
Require On-Site Water Reuse Systems (Grey Water
or Black Water) for Large CII Developments 1 CII X Irrigation / Recycled Water No
Require Plumbing for Gray Water in New SFR
Development 1 SFR X Irrigation / Gray
Water
No
Require Plumbing for Recycled Water in New CII
Development 1 CII X Irrigation /
Recycled Water No
Require Plumbing for Recycled Water in New MFR
Development 1 MFR X Irrigation /
Recycled Water No
Require Rain Barrels in New Development 1 SFR X Irrigation No Require Submetering by Unit for Existing
Commercial Customers 1 CII X All Indoor No
Water Waste Ordinance 5 All X All Outdoor Yes, currently C-11 EKI C40180.00
Agenda Item #8.1:

Conservation Measure/Program Prioritization (a) Sector
Indoor
Outdoor
Primary End Use Local
Program
Table C-2 Prioritization of Conservation Measures and Programs City of Sonoma, Sonoma-Marin Saving Water Partnership
Require Submetering for New MFR Developments 4 MFR X All Indoor No Require Submetering for New Mobile Home Park
Developments 1 MFR X All Indoor No
Require Submetering of Cooling Towers for Existing
Customers 1 CII X Cooling Towers No
Require Submetering of Cooling Towers for New
Development 1 CII X Cooling Towers No
Require Submetering of Existing MFR (and Mobile
Home Park) Customers 1 MFR X All Indoor No
Require Submetering of Landscaping for Existing
MFR and Commercial Customers 1 MFR, CII X Irrigation No Require Submetering of Landscaping for New MFR
and Commercial Developments 1 CII X Irrigation No
Require Swimming Pool and Hot Tub Covers 1 SFR,MFR X Pool/Hot Tub No Require Water Efficiency Plan Reviews for New CII
Development 1 CII XX All Indoor No
Require Weather Adjusting Smart Irrigation
Controllers, Rain Sensors, and/or Soil Moisture
Sensors in New Development
1 All X Irrigation No
Restrict Landscape Irrigation to Designated
Days/Times 1 All X Irrigation No
Water Conserving Landscape and Irrigation Codes,
More Stringent than MWELO 1 All X Irrigation No
Require Submetering by Unit for New Commercial
Developments 3 CII X All Indoor No
Abbreviations
AMI = advanced metering infrastructure MFR = multi-family residential CalWEP = California Water Efficiency Partnership MWELO = Model Water Efficient Landscape Ordinance CII = commercial, industrial, institutional PRV = pressure reducing valve COM = commercial SFR = single-family residential
HEU = High-Efficiency Urinals SMSWP = Sonoma-Marin Saving Water Partnership IRR = irrigation UHET = ultra high efficiency toilet
Notes
(a) Each Water Contractor was asked to rank conservation programs and measures in terms of priority as a locally-administered program, where 5 indicated highest priority and 1 indicated the lowest priority.

C-12 EKI C40180.00
Agenda Item #8.1:

Appendix C: UWMP Preparation Notification Letter
Agenda Item #8.1:

1 Dawn Flores
From: Terrence Erickson <[email protected]>
Sent: Friday, February 27, 2026 5:41 PM
To: [email protected]; [email protected]; Kevin Booker; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; Tony Williams; [email protected]; Matthew Fullner Cc: Mike Berger; Ashley Cotter
Subject: Notice of Preparation of UWMP 2025 - City of Sonoma Attachments: UWMP 60-Day Notice.pdf
 EXTERNAL EMAIL – Use Caution Before Clicking Links or Opening Attachments.

Good afternoon,
Please find attached our oƯicial notice of preparation of an Urban Water Management Plan Update for the City of Sonoma.

Terrence Erickson | Public Works OperaƟons Manager
City of Sonoma | No. 1 The Plaza | Sonoma, CA 95476
Office: (707) 933-2245, Cell: 707-975-0846
[email protected], www.sonomacity.org
City of Sonoma records, including emails, are subject to the California Public Records Act. Unless exemptions apply, this email, any attachments and any replies are subject to disclosure on request, and neither the sender nor any recipients should have any expectation of privacy regarding the contents of such communications.

Agenda Item #8.1:

Agenda Item #8.1:

Agenda Item #8.1:

Appendix D: Public Meeting Notices
Agenda Item #8.1:

PLACEHOLDERPLACEHOLDERPLACEHOLDER
Agenda Item #8.1:

Appendix E: Water Shortage Contingency Plan
Agenda Item #8.1:

Water Shortage Contingency Plan
2025 Update
City of Sonoma
June 2026
Agenda Item #8.1:

Water Shortage Contingency Plan
City of Sonoma
June 2026 2 EKI Environment & Water, Inc.

TABLE OF CONTENTS
1 INTRODUCTION ........................................................................................................................ 4 2 WATER SUPPLY RELIABILITY ANALYSIS..................................................................................... 5 3 PRIOR DROUGHT ACTIONS....................................................................................................... 6 4 ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES.....................................7 5 WATER SHORTAGE LEVELS ..................................................................................................... 11 6 SHORTAGE RESPONSE ACTIONS............................................................................................. 12

6.1 Supply Augmentation or Other Actions. ....................................................................12

6.2 Demand Reduction..................................................................................................... 12

6.3 Operational Changes.................................................................................................. 18

6.4 Mandatory Restrictions.............................................................................................. 18

6.5 Emergency Response Plan.......................................................................................... 18

6.6 Seismic Risk Assessment and Mitigation Plan............................................................19

6.7 Shortage Response Action Effectiveness ...................................................................21 7 COMMUNICATION PROTOCOLS............................................................................................. 28 8 COMPLIANCE AND ENFORCEMENT........................................................................................ 29 9 LEGAL AUTHORITIES ............................................................................................................... 30 10 FINANCIAL CONSEQUENCES OF WSCP................................................................................... 31

10.1 Drought Rate Structures and Surcharges...................................................................31

10.2 Use of Financial Reserves........................................................................................... 31 11 MONITORING AND REPORTING ............................................................................................. 32 12 WSCP REFINEMENT PROCEDURES....................................................................................... 33 13 PLAN ADOPTION, SUBMITTAL, AND AVAILABILITY ................................................................34 Agenda Item #8.1:

Water Shortage Contingency Plan
City of Sonoma
June 2026 3 EKI Environment & Water, Inc.

TABLES
Table 4-1 Annual Assessment Procedures Decision-Making Timeline Table 5-1 Water Shortage Contingency Plan Levels (DWR Table 8-1) Table 6-1 Supply Augmentation and Other Actions (DWR Table 8-3) Table 6-2 Demand Reduction Actions (DWR Table 8-2)
Table 6-3 Preparation Actions for a Catastrophe
Table 6-4 Baseline Residential Per Capita Water Demand
Table 6-5 Baseline Water Use Profile

ATTACHMENTS
Attachment 1. Sonoma County Water Agency Annual Water Supply and Demand Assessment Procedures Attachment 2. Drought Response Tool Quantitative Assessment Attachment 3. Water Shortage Contingency Plan Resolutions Agenda Item #8.1:

Section 1 Water Shortage Contingency Plan
Introduction City of Sonoma
June 2026 4 EKI Environment & Water, Inc.
1 INTRODUCTION
 CWC § 10640
(a) Every urban water supplier required to prepare a plan pursuant to this part shall prepare its plan pursuant to Article 2 (commencing with Section 10630). The supplier shall likewise periodically review the plan as required by Section 10621, and any amendments or changes required as a result of that review shall be adopted pursuant to this article.
(b) Every urban water supplier required to prepare a watershortage contingency plan shall prepare a watershortage contingency plan pursuant to Section 10632. The supplier shall likewise periodically review the water shortage contingency plan as required by paragraph (10) of subdivision (a) of Section 10632 and any amendments or changes required as a result of that review shall be adopted pursuant to this article.

City of Sonoma’s (City’s) Water Shortage Contingency Plan (WSCP) has been developed to serve as a flexible framework of planned response measures to mitigate future water supply shortages. This WSCP builds upon and supersedes the WSCP that was presented in the 2015 Urban Water Management Plan (UWMP).

The WSCP includes the stages of response to a water shortage caused by drought or by supply interruptions caused by infrastructure failure, regulatory mandate, or catastrophic human-caused or natural events. The primary objective of the WSCP is to ensure that the City has in place the necessary resources and management responses needed to protect health and human safety, minimize economic disruption, and preserve environmental and community assets during water supply shortages and interruptions. The WSCP also includes procedures to conduct an annual assessment of water supply and demand in order to determine whether water shortage conditions are likely to exist in the forthcoming year, and to proactively begin the process of implementing WSCP stages of action, as appropriate.

This WSCP has been prepared in accordance with California Water Code (CWC) § 10640 and CWC § 10632 of the Urban Water Management Plan (UWMP) Act. Text from the UWMP Act has been included in grey text boxes with italicized font at beginning of relevant sections of this WSCP. The information presented in the respective WSCP sections and the associated text and tables are collectively intended to fulfill the requirements of that sub-section of the UWMP Act.

Agenda Item #8.1:

Section 2 Water Shortage Contingency Plan
Water Supply Reliability Analysis City of Sonoma
June 2026 5 EKI Environment & Water, Inc.
2 WATER SUPPLY RELIABILITY ANALYSIS
 CWC § 10632 (a) (1) The analysis of water supply reliability conducted pursuant to Section 10635.

This section provides a summary of City’s water supply reliability analysis, recognizing that the WSCP is intended to be a standalone document that can be adopted and amended independently.

The City relies on two main water supply sources, including surface water supplies from the Sonoma County Water Agency (Sonoma Water) and groundwater production.

The reliability analysis was performed based on, among other things, Sonoma Water’s reliability analysis and the total safe yield of the City’s wells. Based on the service reliability analysis, the City is expected to have adequate water supplies during normal hydrologic years and dry years to meet projected demands through 2050.

A Drought Risk Assessment (DRA) was also conducted during the water supply reliability assessment, which evaluates the effects of an assumed five-year drought commencing the year after the assessment is completed (i.e., from 2026 through 2030) on available water supply sources. Based on the DRA, the City is expected to have sufficient water supply from 2026 to 2030. This WSCP addresses potential water shortage conditions and identifies a variety of actions that the City will implement to reduce demands and further ensure supply reliability at various levels of water shortage.

Agenda Item #8.1:

Section 3 Water Shortage Contingency Plan
Prior Drought Actions City of Sonoma
June 2026 6 EKI Environment & Water, Inc.
3 PRIOR DROUGHT ACTIONS
The City has historically developed different strategies for reducing water demand during water shortages, including droughts that occurred from 2014 to 2017, and from 2019 to 2022. The City’s actions in response to these droughts are discussed below.

On 1 April 2015, Governor Brown issued the fourth in a series of Executive Orders regarding actions necessary to address California’s severe drought conditions. Executive Order B-29-15 directed the State Water Resources Control Board (SWRCB) to impose the first ever mandatory restrictions on urban water suppliers to achieve a statewide 25 percent reduction in potable urban water usage through February 2016. The Executive Order also requires commercial, industrial, and institutional (CII) users to implement water efficiency measures, prohibits irrigation with potable water of ornamental turf in public street medians, and prohibits irrigation with potable water outside newly constructed homes and buildings that is not delivered by drip or microspray systems, along with numerous other directives.

On 5 May 2015, the SWRCB adopted Resolution 2015-0032 that mandated minimum actions by water suppliers and their customers to conserve water supplies into 2016 and assigned a mandatory water conservation savings goal to each water supplier based on a measurement of their residential water use in gallons per capita per day (R-GPCD). The Office of Administrative Law approved the regulations and modified the CWC on 18 May 2015. On 2 February 2016, the SWRCB voted to extend the emergency regulations until October 2016 with some modifications. On 9 May 2016, the Governor issued Executive Order B-37-16, which directed the SWRCB to extend the emergency regulations through the end of January 2017 as well as make certain water use restrictions permanent. On 18 May 2016, the SWRCB adopted Resolution 2016-0029 that adjusted the water conservation savings goal and replaced the February 2016 emergency regulation. The SWRCB may take separate action to make some of the requirements of the regulations permanent in response to the Executive Order.

The mandatory conservation standards included in CWC § 865(c) range from 8 percent for suppliers with an R-GPCD below 65 R-GPCD, up to 36 percent for suppliers with an R-GPCD of greater than 215 GPCD. As with previous emergency drought regulations adopted by the SWRCB in 2014, the new water conservation regulation was primarily intended to reduce outdoor urban water use. Based on their R-GPCD, the City was required to reduce water use by 28 percent relative to its 2013 water use.

Through enactment of its WSCP, the City surpassed these reduction targets. During the June 2015 through May 2016 compliance period, the City surpassed its water use reduction target with a cumulative savings of 29.5 percent relative to its 2013 use. In June 2016, the City adopted its 2015 UWMP and associated WSCP update. In April 2017, Governor Brown ended the drought State of Emergency.

Another severe drought impacted the region between 2019 and 2022. In April 2021, after the region experienced record drought, a State of Emergency Proclamation was declared for Sonoma County by the State Governor, and the Sonoma County Board of Supervisors declared a local drought emergency. At this time, Sonoma Water sought 20 percent voluntary conservation from retailers. In response, the City declared a Stage 1 Water Shortage and urged water customers to cut water use by at least 15 percent.

The drought was declared officially over in 2023.

Agenda Item #8.1:

Section 4 Water Shortage Contingency Plan
Annual Water Supply and Demand Assessment Procedures City of Sonoma June 2026 7 EKI Environment & Water, Inc.
4 ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES
 CWC § 10632 (a) (2)
The procedures used in conducting an annual water supply and demand assessment that include, at a minimum, both of the following:
(A) The written decision making process that an urban water supplier will use each year to determine its water supply reliability.
(B) The key data inputs and assessment methodology used to evaluate the urban water supplier’s water supply reliability for the current year and one dry year, including all of the following:
(i) Current year unconstrained demand, considering weather, growth, and other influencing factors, such as policies to manage current supplies to meet demand objectives in future years, as applicable. (ii) Current year available supply, considering hydrological and regulatory conditions in the current year and one dry year. The annual supply and demand assessment may consider more than one dry year solely at the discretion of the urban water supplier.
(iii) Existing infrastructure capabilities and plausible constraints. (iv) A defined set of locally applicable evaluation criteria that are consistently relied upon for each annual water supply and demand assessment.
(v) A description and quantification of each source of water supply.  CWC § 10632.1
An urban water supplier shall conduct an annual water supply and demand assessment pursuant to subdivision (a) of Section 10632 and, on or before July 1 of each year, submit an annual water shortage assessment report to the department with information for anticipated shortage, triggered shortage response actions, compliance and enforcement actions, and communication actions consistent with the supplier’s water shortage contingency plan. An urban water supplier that relies on imported water from the State Water Project or the Bureau of Reclamation shall submit its annual water supply and demand assessment within 14 days of receiving its final allocations, or by July 1 of each year, whichever is later.
 CWC § 10632.2
An urban water supplier shall follow, where feasible and appropriate, the prescribed procedures and implement determined shortage response actions in its water shortage contingency plan, as identified in subdivision (a) of Section 10632, or reasonable alternative actions, provided that descriptions of the alternative actions are submitted with the annual water shortage assessment report pursuant to Section 10632.1. Nothing in this section prohibits an urban water supplier from taking actions not specified in its water shortage contingency plan, if needed, without having to formally amend its urban water management plan or water shortage contingency plan.

On an annual basis, the City will conduct a Supply-Demand Assessment (SDA) to identify whether there is likely to be a water shortage condition in the following year. Because the City’s primary source of potable water supply is from Sonoma Water, the evaluation of Sonoma Water supplies for a particular year will be based on information provided by Sonoma Water. For purposes of this assessment, a water shortage condition is defined as an anticipated shortfall of over 10 percent, corresponding to Water Shortage Level

2. Each element of the SDA is described below, along with the key data inputs and methodologies for determining these elements, and expected timing of the decision process.

1. Evaluation Criteria
The evaluation criteria that will be used to identify whether the City is likely to experience a water shortage in the coming year include:

Agenda Item #8.1:

Section 4 Water Shortage Contingency Plan
Annual Water Supply and Demand Assessment Procedures City of Sonoma June 2026 8 EKI Environment & Water, Inc.
• Sonoma Water Available Supply – Sonoma Water will develop and present the draft annual assessment to the Technical Advisory Committee (TAC) at the April meeting. The final annual assessment will be presented in the June TAC meeting. The City is a member of the TAC and the Water Advisory Committee (WAC) that represents the major cities and water districts that receive water delivered by the Sonoma Water aqueduct system. The City will conduct the Annual Assessment regarding the Sonoma Water available supply as part of a coordinated effort led by Sonoma Water.

Further details about the evaluation criteria and procedure used by Sonoma Water in conducting an Annual Assessment could be found in Attachment 1 of this WSCP. As discussed in Attachment 1, evaluation criteria used by Sonoma Water include:
o Unconstrained customer demand for each of Sonoma Water’s wholesale customers, considering weather, growth, and other influencing factors; o Russian River operations, including current reservoir releases from Lake Sonoma and Mendocino and anticipated releases to meet in-stream flow requirements and water demand;
o Hydrology and watershed conditions, including Lake Sonoma and Lake Mendocino cumulative inflows and storage levels, soil moisture, and snowpack; and
o Potter Valley Project inflows, including Lake Pillsbury storage levels and observed and projected project transfers.
• Groundwater Supply Well Constraints – A comparison of groundwater level elevations to well operational depths to identify the any constraints on accessing the groundwater supply (e.g., dropping water levels due to limited rainfall/runoff) and to identify any potential needs to site and drill additional supply wells and/or rehabilitate existing wells, to the extent economically feasible.
• Local Regulatory Conditions – Evaluation of (1) any new Groundwater Sustainability Agency (GSA) policies (e.g., pumping allocations) or sustainability criteria that could trigger a change in groundwater volume available for pumping, and (2) any new limitations on well permitting that could limit the ability to deepen existing supply wells or drill new supply wells.
• State Regulatory Conditions – Evaluation of any state-mandated drought or water use restrictions known during preparation of the SDA.

These criteria will be assessed by the City staff with detailed knowledge of City operations, including the Public Works Director and the Water Supervisor. The data used to support these assessments may include, but are not limited to, groundwater levels, system demand, and available supply from Sonoma Water.

2. Water Supply
Based on the evaluation criteria above and available supporting information, the City will quantify the projected available supply over the forthcoming year. This quantification will likely be a range, and subject to revision as new data are available and as conditions evolve.

Agenda Item #8.1:

Section 4 Water Shortage Contingency Plan
Annual Water Supply and Demand Assessment Procedures City of Sonoma June 2026 9 EKI Environment & Water, Inc.

3. Unconstrained Customer Demand
Unconstrained customer demands (i.e., the expected water use in the absence of shortage-caused reductions in water use) will be evaluated and estimated for the forthcoming year based on:
• A comparison of monthly customer demands relative to prior years (e.g., last 3 years), • Evaluation of current and anticipated weather conditions, • New demands anticipated during the coming year (e.g., new accounts coming online), and • Any other potentially pertinent factors identified by the City (e.g., pandemic-related stayat-home orders).

4. Planned Water Use for Current Year Considering Dry Subsequent Year The City will compare the estimated unconstrained demands to the anticipated supplies for the current year, assuming that the following year will be dry (i.e., a 10 percentsupply shortfall), using the Evaluation Criteria identified above.

5. Infrastructure Considerations
The City will evaluate how infrastructure capabilities and constraints may affect its ability to deliver supplies to meet expected customer water demands in the coming year. This evaluation will include consideration of both City infrastructure and Sonoma Water infrastructure. The constraints and capabilities are expected to include, among other things:
• Anticipated capital projects and upgrades,
• Anticipated maintenance and repairs, and
• Needed repairs or other actions due to unanticipated emergencies such as fires.

6. Team Members and Decision Makers
The Public Works Director is the primary decision maker, relying on information from and discussions with Sonoma Water and the Water Supervisor.

7. Timeline
Table 4-1 shows the timeline for preparing the annual assessment.

Agenda Item #8.1:

Section 4 Water Shortage Contingency Plan
Annual Water Supply and Demand Assessment Procedures City of Sonoma June 2026 10 EKI Environment & Water, Inc.

Table 4-1 Annual Assessment Procedures Decision-Making Timeline Decision-Making Step Start Date End Date
Determine groundwater supply capacity for the
current year. February April
Obtain Draft Annual Assessment from Sonoma
Water;
Provide Comments on Sonoma Water Draft
Assessment.

April April
Calculate water supply reliability using data from
Sonoma Water and City’s groundwater supply
wells.

March April
Determine shortages and response actions. April May
Prepare and present preliminary report to the
Council if a supply shortage is identified. April May
Update assessment based on final water supplies. April May Prepare decision-making documents for approval
and activating appropriate protocols to declare a
WSCP stage of action as necessary.

May June
Prepare annual water shortage assessment report. May June Obtain the Final Annual Assessment from Sonoma
Water;
Prepare the draft Annual Assessment for a June
Council meeting; and
Implement WSCP actions as approved.

May June
Submit final annual water shortage assessment
report to the State. June
No later than July 1st of
each year beginning in
2022
Consistent with California Water Code (CWC) § 10632.1, the City will perform and submit an SDA to DWR by July 1st of each year beginning in 2022.

Agenda Item #8.1:

Section 5 Water Shortage Contingency Plan
Water Shortage Levels City of Sonoma
June 2026 11 EKI Environment & Water, Inc.
5 WATER SHORTAGE LEVELS
 CWC § 10632 (a) (3)
(A) Six standard water shortage levels corresponding to progressive ranges of up to 10, 20, 30, 40, and 50 percent shortages and greater than 50 percent shortage. Urban water suppliers shall define these shortage levels based on the suppliers’ water supply conditions, including percentage reductions in water supply, changes in groundwater levels, changes in surface elevation or level of subsidence, or other changes in hydrological or other local conditions indicative of the water supply available for use. Shortage levels shall also apply to catastrophic interruption of water supplies, including, but not limited to, a regional power outage, an earthquake, and other potential emergency events.
(B) An urban water supplier with an existing water shortage contingency plan that uses different water shortage levels may comply with the requirement in subparagraph (A) by developing and including a cross-reference relating its existing categories to the six standard water shortage levels.

Consistent with the requirements of CWC § 10632(a)(3), this WSCP is based on the six water shortage levels (also referred to as “stages”) shown in Table 5-1. These stages are intended to address shortage caused by any condition, including the catastrophic interruption of water supplies. Table 5-1 also summarizes the water supply reductions and supply conditions associated with each stage of action.

Table 5-1 Water Shortage Contingency Plan Levels (DWR Table 8-1) ☒ Checked box indicates the supplier uses the standard six levels of water shortage (and supplier will not complete this table).

Standard Shortage
Levels
Percent Shortage
Range
Suppliers Shortage
Levels
Percent Shortage
Range
1 Up to 10% - -
2 Up to 20% - -
3 Up to 30% - -
4 Up to 40% - -
5 Up to 50% - -
6 >50% - -
Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 12 EKI Environment & Water, Inc.
6 SHORTAGE RESPONSE ACTIONS
 CWC § 10632 (a) (4)
Shortage response actions that align with the defined shortage levels and include, at a minimum, all of the following:
(A) Locally appropriate supply augmentation actions.
(B) Locally appropriate demand reduction actions to adequately respond to shortages. (C) Locally appropriate operational changes.
(D) Additional, mandatory prohibitions against specific water use practices that are in addition to state-mandated prohibitions and appropriate to the local conditions.
(E) For each action, an estimate of the extent to which the gap between supplies and demand will be reduced by implementation of the action.
 CWC § 10632 (b)
For purposes of developing the water shortage contingency plan pursuant to subdivision (a), an urban water supplier shall analyze and define water features that are artificially supplied with water, including ponds, lakes, waterfalls, and fountains, separately from swimming pools and spas, as defined in subdivision (a) of Section 115921 of the Health and Safety Code.

This section describes the response actions the City will take to deal with the shortages associated with each of the six stages enumerated in Section 5.

6.1 Supply Augmentation or Other Actions.

There are currently no supply augmentation actions planned in the City’sshortage response actions. Table 6-1 provides other actions the City may take during shortages.

6.2 Demand Reduction
While the WSCP establishes restrictions that are enforceable by penalties and charges, it also establishes methods of reducing consumption, identified in Table 6-2 below. Typically, these restrictions “should” or “may” be done. Demand reduction methods from prior stages stay in effect when more restrictive stages are enacted.

Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 13 EKI Environment & Water, Inc.

Table 6-1 Supply Augmentation and Other Actions (DWR Table 8-3) yes Is the Supplier completing this table using the standard six levels? (yes/no) Shortage
Level
Supply Augmentation
Methods and Other
Actions by Water Supplier
Volume or
Percentage
Shortage Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
1 Expand Public Information
Campaign Percentage 0.5%
The City will implement media campaigns, including:
• Publicize the water shortage and conservation measures using a media campaign, newspaper articles, and website. • Promote water conservation programs.
• Hold water efficiency workshops and public events.
1 Expand Public Information
Campaign Percentage 0.5% Distribute water bill inserts with information about water shortage and conservation. 2 Other Actions (describe) Percentage 1% Continue with action and measures from Stage 1 except where superseded by more stringent requirements.
2 Other Actions (describe) Percentage 4% Accelerate leak detection and repair program. 2 Other Actions (describe) Percentage 2%
Suspend routine flushing of water mains except when necessary to address immediate health or safety concerns or when flushing can be conducted without discharge
2 Other Actions (describe) Percentage 1% Reduce distribution system pressures 3 Other Actions (describe) Percentage 8% Continue with action and measures from Stage 2 except where superseded by more stringent requirements.
3 Implement or Modify Drought
Rate Structure or Surcharge Percentage 4% The City will implement drought rate structure / water budget. 4 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 3 except where superseded by more stringent requirements.
5 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 4 except where superseded by more stringent requirements.
6 Other Actions (describe) Percentage 12% Continue with action and measures from Stage 5 except where superseded by more stringent requirements.
6 Other Actions (describe) Percentage 3% Increase staff enforcement to ensure customers complying with the assigned water budget.

Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 14 EKI Environment & Water, Inc.

Table 6-2 Demand Reduction Actions (DWR Table 8-2)
yes Is the Supplier completing this table using the standard six levels? (yes/no) Shortage
Level
Demand Reduction
Actions
Volume or
Percentage
Shortage
Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
Penalty, Charge,
or Other
Enforcement?
1 Other - Prohibit use
of potable water for
washing hard
surfaces
Percentage 0.5%
Washing sidewalks, walkways, driveways, parking lots and other hard-surfaced areas by direct hosing is not recommended, unless necessary for public health and safety.

No
1 Other - Customers
must repair leaks,
breaks, and
malfunctions in a
timely manner
Percentage 0.5% Breaks or leaks are recommended to be corrected within 72 hours of discovery or notice from the City. No
1 Landscape - Other
landscape restriction
or prohibition
Percentage 0.5%
Irrigation in manner that allows excessive runoff of water, or unreasonably over-sprays the area of irrigation, is not recommended.

No
1 Other - Require
automatic shut of
hoses
Percentage 0.5%
Washing cars, boats, trailers or other vehicles and machinery directly with a hose not equipped with a shutoff nozzle is not recommended.

No
1 Water Features -
Restrict water use
for decorative water
features, such as
fountains
Percentage 0.5% Use of potable water for non-recycling decorative water fountains is not recommended. No
1 CII - Other CII
restriction or
prohibition
Percentage 0.1%
Use of water for single pass evaporative cooling systems for air conditioning is not recommended for all connections installed after 6 June 2000 unless required for health or safety reasons.

No
1 Other - Prohibit
vehicle washing
except at facilities
using recycled or
recirculating water
Percentage 0.1% Use of water for new, non-recirculating conveyor car wash systems is not recommended. No
Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 15 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
Volume or
Percentage
Shortage
Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
Penalty, Charge,
or Other
Enforcement?
1 CII - Other CII
restriction or
prohibition
Percentage 0.1% Use of water for new non-recirculating industrial clothes wash systems is not recommended. No
1 CII - Restaurants may
only serve water
upon request
Percentage 0.1% Restaurants may only serve water upon request. No 1 CII - Lodging
establishment must
offer opt out of linen
service
Percentage 0.1% Hotels and lodging establishments offer a linen service opt-out. No 1 Landscape - Other
landscape restriction
or prohibition
Percentage 1.5% The irrigation with potable water of ornamental turf on public street medians is not recommended. No
1 Landscape - Other
landscape restriction
or prohibition
Percentage 0.1%
Irrigation with potable water outside of newly constructed homes and buildings that is not delivered by drip or microspray systems is not recommended.

No
2 Other Percentage Up to 10% Voluntary action and measures from Stage 1 are now mandatory. Yes 2 Other - Require
automatic shut of
hoses
Percentage 0.5% Use of any garden or utility hose without a hose-end shut-off nozzle is prohibited. Yes
2 Landscape - Limit
landscape irrigation
to specific times
Percentage 1% Irrigation limited to three days per week, and irrigation is limited to the hours between 8pm to 6am. Yes
2 Other - Prohibit use
of potable water for
construction and
dust control
Percentage 0.5% Recycled water must be used for construction dust control. Yes 2 Offer Water Use
Surveys Percentage 1% Conduct water use surveys targeting high water users. Yes Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 16 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
Volume or
Percentage
Shortage
Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
Penalty, Charge,
or Other
Enforcement?
2 Other - Prohibit
vehicle washing
except at facilities
using recycled or
recirculating water
Percentage 1% Car washing shall be allowed only at facilities using recycled or recirculating water. Yes
2 Offer Water Use
Surveys Percentage 0.5% Dedicated irrigation customers are required to conduct the irrigation survey.

Yes
3 Other Percentage Up to 20% Continue with action and measures from Stage 2 except where superseded by more stringent requirements. Yes
3 Landscape - Limit
landscape irrigation
to specific days
Percentage 5%
Irrigation limited to two days per week, and irrigation is limited to the hours between 8pm to 6am. This measure is voluntary under Stage 2 and becomes mandatory under Stage 3.

Yes
3 Pools and Spas -
Require covers for
pools and spas
Percentage 0.1% All pools must be covered when not in use. Yes 4 Other Percentage Up to 30% Continue with action and measures from Stage 3 except where superseded by more stringent requirements. Yes
4 Water Features -
Restrict water use
for decorative water
features, such as
fountains
Percentage 0.5% Filling and/or refilling new and existing decorative water features (i.e. ponds, lakes and fountains) is prohibited. Yes
4 Other water feature
or swimming pool
restriction
Percentage 0.5% Filling new swimming pools is prohibited. Yes 4 Other water feature
or swimming pool
restriction
Percentage 0.5% Filling or topping-off of existing swimming pools is prohibited. Yes 4 Offer Water Use
Surveys Percentage 2% Conduct water use surveys targeting high water users. Yes 4 Landscape - Limit
landscape irrigation
to specific days
Percentage 15% Irrigation limited to one day per week, and irrigation is limited to the hours between 8pm to 6am. Yes
Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 17 EKI Environment & Water, Inc.

Shortage
Level
Demand Reduction
Actions
Volume or
Percentage
Shortage
Gap
Reduction
Value
Additional Explanation or Reference
(OPTIONAL)
Penalty, Charge,
or Other
Enforcement?
5 Other Percentage Up to 40% Continue with action and measures from Stage 4 except where superseded by more stringent requirements. Yes
5 Landscape - Prohibit
all landscape
irrigation
Percentage 12% Use of potable water for irrigation is prohibited for all customers. Yes 5 Other Percentage Up to 22%
All residential and Commercial, Industrial, and Institutional (CII) customers shall reach a water reduction of forty five percent (45%) from previous use.

Yes
6 Other Percentage Up to 50% Continue with action and measures from Stage 5 except where superseded by more stringent requirements. Yes
6 Other Percentage (b) No water-using landscape may be installed in new construction. Yes 6 Other Percentage (b) New construction must offset new demand by conserving one times the new demand within the community. Yes
6 Other Percentage (b) No new water-using landscape may be installed by any customer. Yes 6 Other Percentage Up to 34% All residential and CII customers shall reach a water reduction of fifty five percent (55%) from previous use. Yes
NOTES:
(a) Volumes are percent of demand reduction.
(b) Shortage gap reduction cannot be estimated.

Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 18 EKI Environment & Water, Inc.

6.2.1 Prohibitions on End Uses
Section 13.10.060 of the Municipal Code specifies prohibited water uses, intended to eliminate water waste when a reasonable alternative solution is available. In addition to these mandatory prohibitions, which are in place at all times, the City has incorporated prohibitions against specific water use practices during water shortages. The prohibitions on end uses associated with each Stage of the City’s WSCP are summarized in Table 6-2.

6.2.2 Defining Water Features
 CWC § 10632 (b)
For purposes of developing the water shortage contingency plan pursuant to subdivision (a), an urban water supplier shall analyze and define water features that are artificially supplied with water, including ponds, lakes, waterfalls, and fountains, separately from swimming pools and spas, as defined in subdivision (a) of Section 115921 of the Health and Safety Code.

As required by CWC Section 10632, the City distinguishes between “decorative water features” such as ponds, lakes, and fountains that are artificially supplied with water and “recreational water features” such as swimming pools and spas. Prohibitions on water use for decorative water features are listed separately from those for recreational water features (see Table 6-2).

6.3 Operational Changes
The water shortage response actions included in Table 6-1 include operational changes that the City will implement during each stage of action, including measures to: 1) reduce system losses through a reduction in line flushing and fire training exercises, (2) increase enforcement and patrols, (3) proactive calls to customers, (4) conduct leak surveys during droughts.

6.4 Mandatory Restrictions
The water shortage response actions included in Table 6-2 include a variety of mandatory customer water use restrictions that will be necessary to achieve the targeted demand reductions for the different shortage stages. The types of restrictions and the manner and degree of enforcement for these restrictions vary by stage and are discussed in Section 8.

6.5 Emergency Response Plan
In accordance with the Emergency Services Act, the City has developed an Emergency Operation Plan (EOP). This EOP guides response to unpredicted catastrophic events that might impact water delivery, including regional power outages, earthquakes, or other disasters. The EOP outlines standard operating procedures for all levels of emergency, from minor accidents to major disasters. The EOP has been coordinated with the Sonoma Water and neighboring water purveyors. The following table provides a summary of the actions included in the EOP for specific catastrophic effects.

Table 6-3 summarizes some of the actions in the event of specific catastrophic events.

Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 19 EKI Environment & Water, Inc.

Table 6-3 Preparation Actions for a Catastrophe
Possible Catastrophe Summary of Actions
Earthquake Shut-off isolation valves and use spare
piping for ruptured mains
Earthquake Storage supplies for service interruption
Earthquake Portable and emergency generators
available for City facilities
Earthquake Procedures for assessing water quality,
notifying public and disinfecting system
Flooding Portable and emergency generators
available for City facilities
Flooding Storage supplies for service interruption
Flooding Procedures for assessing water quality,
notifying public and disinfecting system
Toxic Spills (interrupts Sonoma Water
Supply) Use of local groundwater
Toxic Spills (interrupts Sonoma Water
Supply)
Procedures for assessing water quality,
notifying public and disinfecting system
Fire Storage supplies for fire flows
Fire Mutual aid plans and responders identified
Fire Portable and emergency generators
available for City facilities
Power outage or grid failure Portable and emergency generators available for City facilities
Severe Winter Storms Portable and emergency generators
available for City facilities
Hot Weather Portable and emergency generators
available for City facilities

6.6 Seismic Risk Assessment and Mitigation Plan
 CWC § 10632.5
(a) In addition to the requirements of paragraph (3) of subdivision (a) of Section 10632, beginning January 1, 2020, the plan shall include a seismic risk assessment and mitigation plan to assess the vulnerability of each of the various facilities of a water system and mitigate those vulnerabilities. (b) An urban water supplier shall update the seismic risk assessment and mitigation plan when updating its urban water management plan as required by Section 10621.
(c) An urban water supplier may comply with this section by submitting, pursuant to Section 10644, a copy of the most recent adopted local hazard mitigation plan or multihazard mitigation plan under the federal Disaster Mitigation Act of 2000 (Public Law 106-390) if the local hazard mitigation plan or multihazard mitigation plan addresses seismic risk.

Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 20 EKI Environment & Water, Inc.

Impacts associated with earthquakes and liquefaction are discussed in the 2021 Sonoma County MultiJurisdictional Hazard Mitigation Plan (County MJHMP; Sonoma County, 2021). 1 The County MJHMP assesses Sonoma County’s vulnerabilities to various hazards, including seismic hazards, and presents mitigation strategies. The City is included as an annex to the MJHMP.

The County MJHMP includes a discussion of the probability of a seismic event on various faults in the San Francisco Bay Region and concludes that there is a 72 percent chance of one or more earthquakes of magnitude 6.7 of greater on one of the San Francisco Bay Area faults during the next 30 years. The County MJHMP indicates that an earthquake occurring on either the Rodgers Creek or Northern San Andreas fault systems would affect large numbers of people and would result in serious damage to buildings, facilities, and infrastructure. Although the San Andreas Fault has potential for a larger magnitude quake, a major quake on the Rodgers Creek fault has the greatest potential for damage and injury in Sonoma County because the fault is in closer proximity to County population centers along the Highway 101 corridor.

The County examines the exposure and vulnerability of various County assets to earthquake risk. Under the scenario of an earthquake on the Rodgers Creek fault of magnitude 7.19, the resulting damage to structures were projected to be $24.5 billion.

Actions identified in the City’s annex to the MJHMP that mitigate earthquake hazards that may relate to the water utility include, but are not limited to:
• Where appropriate, support retrofitting, purchase or relocation of structures located in hazard areas, prioritizing those that have experienced repetitive losses and/or are located in high- or medium-risk hazard areas.
• Integrate the hazard mitigation plan into other plans, ordinances and programs that dictate land use decisions in the community, including the City’s General Plan, Development Code, Urban Water Management Plan, Risk and Resilience Assessment and Emergency Response Plan, Sonoma Water’s Water Supply Strategies Action Plan, Greenhouse Gas Emissions Reduction Action Plan, Climate Action Plan, Capital Improvement Program and Flood Damage Prevention Regulations. • Purchase generators for critical facilities and infrastructure that lack adequate emergency backup power, including Sonoma City Hall complex and pre-designated emergency shelters. • Expedite the funding and retrofit of seismically deficient city-owned bridges and road structures by working with Caltrans and other appropriate governmental agencies, including the replacement of the structurally deficient Chase Street Bridge. • Conduct comprehensive programs to identify and mitigate problems with facility contents, architectural components, and equipment that will prevent critical buildings from being functional after major natural disasters. Such contents and equipment includes computers and servers, phones, files, and other tools used by staff to conduct daily business. • Support and encourage planning and identification of facilities for the coordination of distribution of water, food, blankets, and other supplies, coordinating this effort with the American Red Cross. • Develop and implement a program to capture and maintain data after significant events (e.g. high water marks, preliminary damage estimates, damage photos, etc.) to support future mitigation efforts including the implementation and maintenance of the hazard mitigation plan. 1 The County MJHMP could be found in the following website: https://permitsonoma.org/hazard-mitigation Agenda Item #8.1:

Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 21 EKI Environment & Water, Inc.
• Acquire software and hardware, and associated training, to assist with plan reviews, permitting, inspections, and records retention to help support the identification and mitigation of structures and projects located in hazard prone areas and to quickly and efficiently aid in post-disaster recovery efforts.

The County is in the process of updating its MJHMP, but as of the date of preparation of this WSCP, it was not yet finalized.

Discussion of seismic risks specific to the Sonoma Water system is provided in the Sonoma County Water Agency Local Hazard Mitigation Plan, dated 19 September 2024 (Sonoma Water LHMP; Sonoma Water, 2024). The Sonoma Water LHMP specifically assesses Sonoma Water’s natural hazard risks and vulnerabilities facing Sonoma Water infrastructure and provides a plan of action to address these vulnerabilities. The Sonoma Water LHMP identifies a series of mitigation measures to address seismic risk, including seismic retrofits of distribution system components to protect against damage due to liquefaction and lateral spread hazard and installation of automated throttling valves at aqueducts and interties to minimize uncontrolled releases out of Sonoma Water facilities.

6.7 Shortage Response Action Effectiveness
In order to evaluate and ensure that effective actions will be implemented with the proper level of intensity, the City employed the Drought Response Tool (DRT), an Excel spreadsheet model developed by EKI Environment and Water, Inc. The DRT model calculates monthly savings anticipated by implementing each stage of action as detailed below.

6.7.1 Baseline Water Use Profile
Using the DRT, the City developed a pre-drought baseline water use profile that reflected usage patterns within the City’s service area by major water use sector during 2019 that was used to guide development of the WSCP, as this year was considered a normal water year. Key findings from this analysis are presented below.

Residential Per Capita Demand
The City’s baseline residential gallons per capita per day (R-GPCD) demand during 2019 was approximately 101 R-GPCD. As shown in Table 6-4, this R-GPCD is significantly greater than the statewide average of 85 R-GPCD.

Proportion of Outdoor Water Use
As shown in Table 6-4 and associated charts, outdoor water use, which can generally be considered as a “discretionary water use”, was estimated to be approximately 45 percent of the City’s potable consumption during this pre-drought time period. Dedicated irrigation meters for potable water accounted for 6 percent of the total potable irrigation demand. The remaining irrigation water uses within the City’s service area are supplied by recycled water.

The DRT estimates indoor water use to be equivalent to the lowest monthly water use for each sector, accounting for the number of days in each month. Outdoor water use for each sector was estimated to be the difference between the total water use and the estimated indoor water use. If City customers tend to irrigate more heavily during winter months, an underestimation of the proportion of outdoor water use would occur.

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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 22 EKI Environment & Water, Inc.

The proportion of outdoor water use within the residential and commercial sectors are estimated to be 56 percent and 31 percent, respectively. This indicates that there is the potential to achieve significant potable water savings across these sectors, simply by focusing on outdoor uses. If the proportion of outdoor water use is being underestimated by the DRT method, then even more substantial savings may be achieved through targeting outdoor water use. As further shown in Table 6-5 and its associated charts, the seasonal variation in baseline potable water use reflects increased irrigation demands during the summer and fall months. Therefore, the greatest potential for reductions in non-essential water use are expected during these months.

Table 6-4 Baseline Residential Per Capita Water Demand
Baseline Residential Per Capita
Water Demand
(R-GPCD)
Sonoma (a) 100
Statewide Average (b) 85
NOTES:
(a) Sonoma R-GPCD calculated using 2019 metered data.
(b) State-wide R-GPCD for 2019 obtained from data provided at California State Water Resources Control Board Water Conservation Portal - Conservation Reporting, http://www.waterboards.ca.gov/water_issues/programs/conservation_portal/conservation_r eporting.shtml, accessed March 2021.

Residential
64%
CII
12%
Dedicated
Irrigation
6%
Non-Revenue
18%
Chart 6-5A Baseline Year (2019) Percent Annual Water
Use by Sector
Residential CII Dedicated Irrigation Non-Revenue
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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 23 EKI Environment & Water, Inc.
44%
69%
37%
56%
31%
100%
45%
100%
18%
0 500
1,000
1,500
2,000
2,500
Residential CII Dedicated
Irrigation
Non-Revenue Total
Annual Water Use (AF)
Chart 6-5B Baseline Year (2019) Annual Water Use by
Sector and End Use
Indoor Outdoor Non-Revenue
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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 24 EKI Environment & Water, Inc.

Table 6-5 Baseline (2019) Water Use Profile
Sector End-Use
JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecemberAnnual Annual
% of
Total by
Sector
Residential Indoor 50 45 50 48 50 48 50 50 48 50 48 50 589 29% Outdoor 9 7 0 35 70 91 116 130 98 108 61 10 736 35%
Subtotal Residential 59 52 50 84 120 140 166 180 147 158 109 60 1,326 64% CII Indoor 15 13 15 14 15 14 15 15 14 15 14 15 171 8%
Outdoor 2 1 0 6 8 9 11 14 9 12 6 1 78 4%
Subtotal CII 17 14 15 20 22 23 26 28 23 26 20 16 249 12% Dedicated Irrigation Outdoor 2 3 1 4 13 14 19 22 18 16 9 2 123 6% Non-Revenue Non-Revenue 12 14 32 2 20 7 72 2 53 47 57 51 369 18% Total Indoor 65 58 65 62 65 62 65 65 62 65 62 65 760 37% Outdoor 13 11 1 45 90 114 146 166 125 136 76 13 937 45% Non-Revenue 12 14 32 2 20 7 72 2 53 47 57 51 369 18%
Total 89 83 98 109 175 184 283 233 240 248 196 128 2,067 100% NOTES:
(a) Volumes are in units of AF.
(b) Indoor water use was estimated to be the lowest monthly water use for each sector, accounting for the number of days in each month. Outdoor water use for each sector was estimated to be the difference between the total water use and the estimated indoor water use.

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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 25 EKI Environment & Water, Inc.
0 50
100
150
200
250
300
January February March April May June July August September October November December Water Use (AF)
Chart 6-6A Baseline Year (2019) Monthly Total Water Use by Sector Residential CII Dedicated Irrigation Non-Revenue
0 50
100
150
200
250
300
January February March April May June July August September October November December Water Use (AF)
Chart 6-6B Baseline Year (2019) Monthly Indoor vs. Outdoor Water Use Indoor Outdoor Non-Revenue
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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 26 EKI Environment & Water, Inc.

6.7.2 Shortage Response Action Effectiveness
The DRT provides a quantitative framework that allows the City to systematically estimate the monthly and cumulative annual demand reductions expected to result from particular combinations of drought response actions and associated implementation rates. Data inputs to the DRT include total production, class-specific water use, population, and assumptions regarding the split between indoor and outdoor water use for each customer class.

For each drought response action, the user specifies:
• The customer class(es) and end use(s) that are affected; • The percent savings for that end use for each account that implements the action. These are based on evaluations reported in the literature, or where such studies are not available, on best estimates based on the City’s experience; and
• The percentage of accounts assumed to implement the action, which is presumed to be the result of the intensity level of the City’s program implementation, including but not limited to, marketing and enforcement activities.

An additional critical DRT user input is a set of constraints on demand reductions to ensure that usage levels do not endanger health and safety or result in unacceptable economic impacts. The DRT will not permit estimated usage reductions to violate these constraints, regardless of the demand reduction actions selected. The constraints are:
• A minimum residential indoor per capita daily usage of 25 gallons, • A maximum residential outdoor usage reduction of 100 percent, • A maximum Commercial, industrial, and institutional (CII) indoor usage reduction of 30 percent, and
• A maximum CII outdoor usage reduction of 100 percent.

Based on the foregoing data, the DRT model calculates the resulting monthly savings. The City adjusted the combination of actions and implementation levels to achieve the targeted savings levels at each of the six stages of action.

For each stage of action, the modeling targeted the mid-range of the required demand reduction range:
• 5 percent for Stage 1,
• 15 percent for Stage 2,
• 25 percent for Stage 3,
• 35 percent for Stage 4,
• 45 percent for Stage 5, and
• 55 percent for Stage 6.

The key DRT inputs and outputs for each of the stages of action are reproduced in Attachment 2.

Table 6-2 shows the water shortage reduction actions, savings assumptions, and implementation rates that are required for the City to achieve the required annual demand reductions for each of the six stages of action. At each stage, there are two types of demand-reduction actions identified:

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Section 6 Water Shortage Contingency Plan
Shortage Response Actions City of Sonoma
June 2026 27 EKI Environment & Water, Inc.
• Restrictions on customer water usage; and
• Consumption reduction actions by the City to encourage decreased water usage.

Many actions are implemented across a number of stages, some at increasing implementation levels.

Therefore, the actions in Table 6-1 and Table 6-2 are listed as a row under the first stage at which they are implemented. The percentages shown in the tables represent savings of the end uses.

Agenda Item #8.1:

Section 7 Water Shortage Contingency Plan
Communication Protocols City of Sonoma
June 2026 28 EKI Environment & Water, Inc.
7 COMMUNICATION PROTOCOLS
 CWC § 10632 (a) (5)
Communication protocols and procedures to inform customers, the public, interested parties, and local, regional, and state governments, regarding, at a minimum, all of the following:
(A) Any current or predicted shortages as determined by the annual water supply and demand assessment described pursuant to Section 10632.1.
(B) Any shortage response actions triggered or anticipated to be triggered by the annual water supply and demand assessment described pursuant to Section 10632.1.
(C) Any other relevant communications.

Each stage of the WSCP is implemented with a formal declaration by City Council upon the determination that Sonoma Water or another governing authority (e.g., the SWRCB) has required a voluntary or mandatory reduction in water use due to a water supply shortage or emergency.

Even before formal declaration of a water shortage, a public information program will be activated to provide customers with as much advance notice as possible. Following declaration of a shortage, City customers would need to be provided notice of water shortage rules and regulations via a variety of media and communications methods.

Coordination between the City and with other public agencies can begin prior to formal declaration of a water shortage and can be accomplished through regular meetings, e-mail group updates, and presentations. In a regional water shortage scenario, the City would use public outreach resources and materials provided by Sonoma Water. In addition to these materials, the City may develop its own materials to communicate with customers, such as a dedicated customer service hotline, and expand its normal public outreach to support its water conservation efforts (see Chapter 9 of the City’s 2025 UWMP).

As discussed in Chapter 9 of the 2025 UWMP, one City staff member currently has primary responsibility for water conservation. Staff time dedicated to water conservation and enforcement action will increase with the severity of a supply shortage. Additional duties may be assigned to current employees or hiring of temporary staff may be considered to meet staffing needs during extreme water shortages.

In summary, the general steps involved in the communication include the following:
• If a water shortage is anticipated based on the preliminary evaluations performed for the Annual Assessment described in Section 5, the City will initiate a public information program, providing customers with notice of anticipated water shortage rules and regulations. • At this time, the City will commence coordination with other public agencies via regular meetings, e-mail group updates, and presentations.
• Any change in stage of the WSCP will be implemented by a formal declaration by the City Council. The City will post declarations on its website and other multi-media outlets as feasible.

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Section 8 Water Shortage Contingency Plan
Compliance and Enforcement City of Sonoma
June 2026 29 EKI Environment & Water, Inc.
8 COMPLIANCE AND ENFORCEMENT
 CWC § 10632 (a) (6) For an urban retail water supplier, customer compliance, enforcement, appeal, and exemption procedures for triggered shortage response actions as determined pursuant to Section 10632.2.

In the event of demand reduction stage 1-6 violations to the City’s respective stage water waste prohibitions and requirements, non-essential user/actions, and/or allocation reduction, the City follows the following sequence:
(1) written notice of infraction or administrative penalties; and (2) flow restricting devices or water shutoff (as consistent with current regulations).

Administrative penalties shall be $100 for first violation, $200 for second violation, and $300 for third or subsequent violations.

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Section 9 Water Shortage Contingency Plan
Legal Authorities City of Sonoma
June 2026 30 EKI Environment & Water, Inc.
9 LEGAL AUTHORITIES
 CWC § 10632 (a) (7)
(A) A description of the legal authorities that empower the urban water supplier to implement and enforce its shortage response actions specified in paragraph (4) that may include, but are not limited to, statutory authorities, ordinances, resolutions, and contract provisions.
(B) A statement that an urban water supplier shall declare a water shortage emergency in accordance with Chapter 3 (commencing with Section 350) of Division 1.
(C) A statement that an urban water supplier shall coordinate with any city or county within which it provides water supply services for the possible proclamation of a local emergency, as defined in Section 8558 of the Government Code.

Under California law, including CWC Chapters 3.3 and 3.5 of Division 1, Parts 2.55 and 2.6 of Division 6, Division 13, and Article X, Section 2 of the California Constitution, the City Council is authorized to implement the water shortage actions outlined in this WSCP. In all water shortage cases, shortage response actions to be implemented will be at the discretion of the City Council and will be based on an assessment of the supply shortage, customer response, and need for demand reductions.

It is noted that upon proclamation by the Governor of a state of emergency under the California Emergency Services Act (Chapter 7 [commencing with Section 8550] of Division 1 of Title 2 of the Government Code) based on drought conditions, the state will defer to implementation of locally adopted water shortage contingency plans to the extent practicable. The City will coordinate with Sonoma County within which it provides water supply services as well as other regional and local water suppliers for possible proclamation of a local emergency, as necessary. The City shall declare a water shortage emergency in accordance with Water Code Chapter 3 (commencing with Section 350) of Division 1 general provision regarding water shortage emergencies.

The City has authority under Chapter 13.10 of the Sonoma Municipal Code to require water rationing and conservation and to enforce penalties. Relevant code sections and an adopted water shortage contingency resolution are included as Attachment 3 of this WSCP.

The City’s WSCP update was adopted on 3 June 2026. The adoption ordinance is included as Attachment 3 of the City’s UWMP.

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Section 10 Water Shortage Contingency Plan
Financial Consequences of WSCP City of Sonoma
June 2026 31 EKI Environment & Water, Inc.
10 FINANCIAL CONSEQUENCES OF WSCP
 CWC § 10632 (a) (8)
A description of the financial consequences of, and responses for, drought conditions, including, but not limited to, all of the following:
(A) A description of potential revenue reductions and expense increases associated with activated shortage response actions described in paragraph (4).
(B) A description of mitigation actions needed to address revenue reductions and expense increases associated with activated shortage response actions described in paragraph (4). (C) A description of the cost of compliance with Chapter 3.3 (commencing with Section 365) of Division 1.

The greater the water shortage stage enacted, the greater the financial impacts to the City of Sonoma due to reduced revenue from water sales. This reduced revenue would be balanced to some degree due to a commensurate reduction in costs to purchase a reduced volume of water from the Sonoma Water. In addition, the City would have the option of deferring planned capital expenditures and utilizing its utility system reserves. To further offset these impacts, the City may enact drought rate structures and surcharges as described below and meet remaining financial shortfalls through the use of reserves.

10.1 Drought Rate Structures and Surcharges
Well-designed drought rate structures can reduce the potential financial effects of water shortages and enable the supplier to recover its purchase, treatment, and delivery costs, as well as the additional costs related to the water shortage response program.

The City has increasing block/tier volumetric water rates for its single-family residential customer class.

Multi-family residential, commercial and dedicated irrigation customer classes have uniform water rates.

The City’s water rate structure was revised in 2023 and is consistent with current law. The City’s current water rates can be found on the City’s website at: https://www.sonomacity.org/water-rates/.

Reductions in water use will affect the revenue that the City receives from its commodity charges, because less water will be sold. The anticipated revenue from commodity charges can be calculated by subtracting the revenue generated from monthly service charges from the total budgeted revenue.

10.2 Use of Financial Reserves
The City has a Water Utility Fund Rate Stabilization Reserve that is to be used during periods of short-term revenue shortages due to economic recession, drought, or other causes, to alleviate the need to quickly implement substantial rate increases. Beginning in Fiscal Year 2018-2019, the Water Utility Rate Stabilization Reserve target level was 11 percent of annual Volumetric Charge revenue. The Water Utility Rate Stabilization Reserve will be increased by 1 percent every year, until it reaches a targeted 15 percent of annual Volumetric Charge revenue. Use of the Water Utility Fund Rate Stabilization Reserve can be during periods of short-term revenue shortages caused by economic recession, drought, or other reasons, by direction of City Council.

Agenda Item #8.1:

Section 11 Water Shortage Contingency Plan
Monitoring and Reporting City of Sonoma
June 2026 32 EKI Environment & Water, Inc.
11 MONITORING AND REPORTING
 CWC § 10632 (a) (9) For an urban retail water supplier, monitoring and reporting requirements and procedures that ensure appropriate data is collected, tracked, and analyzed for purposes of monitoring customer compliance and to meet state reporting requirements.

The City’s local groundwater supply and Sonoma Water supply turnouts are all equipped with water meters. In addition, each potable water customer is metered. Non-residential landscape irrigation is metered separately from indoor use at most non-residential sites. The City reads meters on a monthly basis and is able to document both demand reductions and atypically high water use. The City contacts individual customers to resolve issues related to atypically high water use. The City completed installation of advanced metering infrastructure (AMI) for all meters as of 2025.

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