Napa City Council
June 16, 2026

CITY OF NAPA
MAY
2026

PREPARED BY

PUBLIC DRAFT
2025 URBAN WATER

MANAGEMENT PLAN
ATTACHMENT 3

PUBLIC DRAFT | MAY 2026

2025 Urban Water Management Plan

Prepared for
City of Napa

Project No. 424-60-26-28

Prepared by: Amy Kwong, PE Date

QA/QC Review: Elizabeth Drayer, PE Date

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
i City of Napa
2025 Urban Water Management Plan
May 2026

Table of Contents
EXECUTIVE SUMMARY ................................ ................................ ................................ .................. ES-1 Introduction ....................................................................................................................................... ES-1 California Water Code Requirements ............................................................................................... ES-1 City Water System ............................................................................................................................. ES-2 Water Use by City Customers ............................................................................................................ ES-2 City Water Supplies ........................................................................................................................... ES-4 Conservation Target Compliance ...................................................................................................... ES-4 City Water Service Reliability ............................................................................................................ ES-4 Water Shortage Contingency Plan .................................................................................................... ES-5 UWMP Preparation, Review, and Adoption ...................................................................................... ES-5 CHAPTER 1 Introduction ................................ ................................ ................................ .................. 1-1

1.1 Introduction ................................................................................................................................... 1-1

1.2 Importance and Extent of City’s Water Management Planning Efforts ........................................ 1-1

1.3 Changes from 2020 UWMP ........................................................................................................... 1-1

1.4 Demonstration of Consistency with the Delta Plan for Participants in Covered Actions ............. 1-2

1.5 Plan Organization .......................................................................................................................... 1-3 CHAPTER 2 Plan Preparation ................................ ................................ ................................ ........... 2-1

2.1 Basis for Preparing a Plan .............................................................................................................. 2-1

2.2 Regional Planning .......................................................................................................................... 2-1

2.3 Individual or Regional Planning and Compliance .......................................................................... 2-2

2.4 Fiscal or Calendar Year and Units of Measure .............................................................................. 2-2

2.5 Coordination and Outreach ........................................................................................................... 2-3

2.5.1 Wholesale and Retail Coordination ..................................................................................... 2-3

2.5.2 Coordination with Other Agencies and the Community ..................................................... 2-3

2.5.3 Notice to Cities and Counties ............................................................................................... 2-4 CHAPTER 3 Service Area Description ................................ ................................ ................................ 3-1

3.1 General Description ....................................................................................................................... 3-1

3.2 Service Area Description ............................................................................................................... 3-1

3.3 Water System Description ............................................................................................................. 3-3

3.4 Water Division ............................................................................................................................... 3-4

3.5 Service Area Climate ...................................................................................................................... 3-7

3.5.1 Historical Climate ................................................................................................................. 3-7

3.5.2 Potential Effects of Climate Change .................................................................................... 3-8

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Table of Contents

3.6 Service Area Population and Demographics ................................................................................. 3-8

3.6.1 Service Area Population ....................................................................................................... 3-8

3.6.2 Other Social, Economic, and Demographic Factors ............................................................. 3-9

3.7 Land Uses Within Service Area .................................................................................................... 3-10

3.7.1 Current and Projected Land Uses ...................................................................................... 3-10

3.7.2 Long-Range Land Use Planning .......................................................................................... 3-10 CHAPTER 4 Water Use Characterization ................................ ................................ ........................... 4-1

4.1 Non-Potable Versus Potable Water Use ....................................................................................... 4-1

4.2 Water Use by Sector ...................................................................................................................... 4-1

4.2.1 Historical Water Use ............................................................................................................ 4-2

4.2.2 Current Water Use ............................................................................................................... 4-3

4.2.3 Projected Water Use ............................................................................................................ 4-4

4.2.3.1 25-Year Planning Horizon ........................................................................................... 4-4

4.2.3.2 Characteristic Five-Year Water Use ............................................................................ 4-6

4.3 Distribution System Water Losses ................................................................................................. 4-6

4.4 Estimating Future Water Savings .................................................................................................. 4-9

4.5 Water Use for Lower Income Households .................................................................................... 4-9

4.6 Climate Change Considerations................................................................................................... 4-10 CHAPTER 5 SB X7-7 Baselines, 2020 Target, and 2025 Reporting ................................ ....................... 5-1

5.1 Overview and Background ............................................................................................................ 5-1

5.2 2020 Daily Per Capita Water Use Compliance .............................................................................. 5-1

5.3 Service Area Population ................................................................................................................ 5-2

5.4 Gross Water Use ............................................................................................................................ 5-3

5.5 2025 Compliance Daily Per Capita Water Use .............................................................................. 5-4

5.6 Regional Alliance ........................................................................................................................... 5-4 CHAPTER 6 Normal-Year Water Supply Characterization ................................ ................................ .. 6-1

6.1 Overview ........................................................................................................................................ 6-1

6.2 Imported Water: State Water Project ........................................................................................... 6-1

6.2.1 Carryover Water .................................................................................................................. 6-3

6.2.2 North of Delta Allocation ..................................................................................................... 6-3

6.2.3 Advanced Table A Program .................................................................................................. 6-3

6.2.4 Article 21 Water ................................................................................................................... 6-3

6.2.5 Dry Year Water ..................................................................................................................... 6-4

6.3 Local Surface Water ....................................................................................................................... 6-4

6.3.1 Milliken Reservoir ................................................................................................................ 6-4

6.3.2 Lake Hennessey .................................................................................................................... 6-5

6.4 Groundwater ................................................................................................................................. 6-5 ATTACHMENT 3

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Table of Contents

6.5 Stormwater .................................................................................................................................... 6-6

6.6 Wastewater and Recycled Water .................................................................................................. 6-6

6.6.1 Recycled Water Coordination .............................................................................................. 6-6

6.6.2 Wastewater Collection, Treatment, and Disposal ............................................................... 6-7

6.6.2.1 Wastewater Collected Within Service Area ............................................................... 6-7

6.6.2.2 Wastewater Treatment and Discharge Within Service Area ..................................... 6-7

6.6.3 Potential, Current, and Projected Recycled Water Uses ................................................... 6-11

6.6.4 Actions to Encourage and Optimize Future Recycled Water Use ...................................... 6-13

6.7 Desalinated Water ....................................................................................................................... 6-13

6.8 Exchanges and Transfers ............................................................................................................. 6-14

6.9 Future Water Projects ................................................................................................................. 6-14

6.9.1 Water Treatment Plant Projects ........................................................................................ 6-14

6.9.2 Sites Reservoir .................................................................................................................... 6-15

6.9.3 Advanced Water Purification Facility ................................................................................. 6-16

6.9.4 Joint Powers Agreement or Other Cooperative Agreement with Other Local Entities ..... 6-17

6.10 Summary of Existing and Planned Sources of Water ................................................................ 6-18

6.11 Climate Change Impacts ............................................................................................................ 6-20

6.12 Energy Intensity ......................................................................................................................... 6-21 CHAPTER 7 Water Service Reliability and Drought Risk Assessment ................................ .................. 7-1

7.1 Water Service Reliability Assessment............................................................................................ 7-1

7.1.1 Constraints on Water Sources ............................................................................................. 7-1

7.1.1.1 Climate Variability ...................................................................................................... 7-1

7.1.1.2 Environmental/Legal Restrictions .............................................................................. 7-1

7.1.1.3 Water Quality ............................................................................................................. 7-2

7.1.2 Year Type Characterization .................................................................................................. 7-3

7.1.2.1 Basis of Water Year Data – Local Surface Water ........................................................ 7-3

7.1.2.2 Basis of Water Year Data – SWP ................................................................................. 7-6

7.1.3 Water Service Reliability ...................................................................................................... 7-8

7.1.3.1 Water Service Reliability – Normal Year .................................................................... 7-8

7.1.3.2 Water Service Reliability – Single Dry Year ................................................................ 7-9

7.1.3.3 Water Service Reliability – Five Consecutive Dry Years ............................................. 7-9

7.1.4 Water Management Tools and Options ............................................................................ 7-10

7.2 Drought Risk Assessment ............................................................................................................ 7-10

7.2.1 Data, Methods, and Basis for Water Shortage Condition.................................................. 7-11

7.2.2 DRA Water Source Reliability ............................................................................................. 7-11

7.2.3 Total Water Supply and Use Comparison .......................................................................... 7-12 CHAPTER 8 Water Shortage Contingency Plan ................................ ................................ .................. 8-1

8.1 Water Shortage Contingency Plan Background ............................................................................ 8-1

8.2 Water Shortage Contingency Plan................................................................................................. 8-1

ATTACHMENT 3

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iv City of Napa
2025 Urban Water Management Plan
May 2026

Table of Contents

8.3 Water Supply Reliability Analysis Summary .................................................................................. 8-1

8.4 Seismic Risk Assessment and Mitigation Plan ............................................................................... 8-2

8.5 Water Shortage Contingency Plan Adoption, Submittal, and Availability .................................... 8-3 CHAPTER 9 Demand Management Measures ................................ ................................ ................... 9-1

9.1 Water Conservation Program Overview ....................................................................................... 9-1

9.2 Existing and Planned Demand Management Measures ............................................................... 9-1

9.2.1 Water Waste Prevention Ordinances .................................................................................. 9-2

9.2.1.1 DMM Description ....................................................................................................... 9-2

9.2.1.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-2

9.2.1.3 Plans for Continued Implementation ......................................................................... 9-2

9.2.2 Metering .............................................................................................................................. 9-2

9.2.2.1 DMM Description ....................................................................................................... 9-2

9.2.2.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-3

9.2.2.3 Plans for Continued Implementation ......................................................................... 9-3

9.2.3 Conservation Pricing ............................................................................................................ 9-3

9.2.3.1 DMM Description ....................................................................................................... 9-3

9.2.3.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-3

9.2.3.3 Plans for Continued Implementation ......................................................................... 9-4

9.2.4 Public Education and Outreach ............................................................................................ 9-4

9.2.4.1 DMM Description ....................................................................................................... 9-4

9.2.4.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-5

9.2.4.3 Plans for Continued Implementation ......................................................................... 9-6

9.2.5 Programs to Assess and Manage Distribution System Real Loss ......................................... 9-6

9.2.5.1 DMM Description ....................................................................................................... 9-6

9.2.5.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-6

9.2.5.3 Plans for Continued Implementation ......................................................................... 9-6

9.2.6 Water Conservation Program Coordination and Staffing Support ...................................... 9-6

9.2.6.1 DMM Description ....................................................................................................... 9-6

9.2.6.2 Implementation over the Past Five Years to Achieve Water Use Targets ................. 9-7

9.2.6.3 Plans for Continued Implementation ......................................................................... 9-7

9.2.7 Other Demand Management Measures .............................................................................. 9-7

9.2.7.1 Water Conservation Services ..................................................................................... 9-7

9.2.7.1.1 DMM Description .............................................................................................. 9-7

9.2.7.1.2 Implementation over the Past Five Years to Achieve Water Use Targets ........ 9-8

9.2.7.1.3 Plans for Continued Implementation ............................................................... 9-8

9.2.7.2 Rebate Programs ........................................................................................................ 9-9

9.2.7.2.1 DMM Description .............................................................................................. 9-9

9.2.7.2.2 Implementation over the Past Five Years to Achieve Water Use Targets ........ 9-9

9.2.7.2.3 Plans for Continued Implementation ............................................................... 9-9

9.2.7.3 Commercial, Industrial, and Institutional Conservation Programs .......................... 9-10

9.2.7.3.1 DMM Description ............................................................................................ 9-10

9.2.7.3.2 Implementation over the Past Five Years to Achieve Water Use Targets ...... 9-10

9.2.7.3.3 Plans for Continued Implementation ............................................................. 9-10 ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
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2025 Urban Water Management Plan
May 2026

Table of Contents

9.3 California Water Efficiency Partnership ...................................................................................... 9-10

9.3.1 Urban Water Use Objectives ............................................................................................. 9-11

9.3.1.1 Annual Water Use Reporting.................................................................................... 9-12 CHAPTER 10 Plan Adoption, Submittal, and Implementation ................................ .......................... 10-1

10.1 Inclusion of All 2025 Data .......................................................................................................... 10-1

10.2 Notice of Public Hearing ............................................................................................................ 10-1

10.2.1 Notices to Cities and Counties ......................................................................................... 10-1

10.2.2 Notice to the Public ......................................................................................................... 10-2

10.3 Public Hearing and Adoption ..................................................................................................... 10-2

10.3.1 Public Hearing .................................................................................................................. 10-3

10.3.2 Adoption .......................................................................................................................... 10-3

10.4 Plan Submittal ........................................................................................................................... 10-3

10.5 Public Availability ....................................................................................................................... 10-3

10.6 Plan Implementation ................................................................................................................. 10-3

10.7 Amending an Adopted UWMP or Water Shortage Contingency Plan ...................................... 10-4

LIST OF TABLES
Table 2-1. Public Water Systems (DWR Table 2-1 Retail).................................................................... 2-1 Table 2-2. Plan Identification (DWR Table 2-2) ................................................................................... 2-2 Table 2-3. Supplier Identification (DWR Table 2-3) ............................................................................. 2-2 Table 2-4. Water Supplier Information Exchange (DWR Table 2-4 Retail) .......................................... 2-3 Table 3-1. Monthly Average Climate Data Summary .......................................................................... 3-7 Table 3-2. Population - Current and Projected (DWR Table 3-1 Retail) .............................................. 3-9 Table 4-1. Historical Water Use by Sector ........................................................................................... 4-2 Table 4-2. Total Uses for Potable and Non-Potable Water – Actual (DWR Table 4-1 Retail) ............. 4-3 Table 4-3. Total Uses for Potable and Non-Potable Water – Projected (DWR Table 4-2 Retail) ........ 4-5 Table 4-4. Projected Potable Water Demands for Drought Risk Assessment ..................................... 4-6 Table 4-5. Last Five Years of Water Loss Audit Reporting (DWR Table 4-5 Retail) ............................. 4-7 Table 4-6. Progress Towards 2028 Water Loss Standard (DWR Table 4-6 Retail) .............................. 4-8 Table 4-7. Inclusion in Water Use Projections (DWR Table 4-3 Retail) ............................................... 4-9 Table 4-8. Projected Water Demands for Lower Income Households .............................................. 4-10 Table 5-1. SB X7-7 2020 Target Progress (DWR Table 5-1 Retail) ....................................................... 5-2 Table 5-2. Method for 2025 Population Estimate (SB X7-7 Table 2) ................................................... 5-3

ATTACHMENT 3

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2025 Urban Water Management Plan
May 2026

Table of Contents
Table 5-3. 2025 Service Area Population (SB X7-7 Table 3) ................................................................ 5-3 Table 5-4. 2025 Gross Water Use (SB X7-7 Table 4) ............................................................................ 5-4 Table 5-5. 2025 Gallons Per Capita Per Day (SB X7-7 Table 5) ............................................................ 5-4 Table 6-1. Groundwater Volume Pumped (DWR Table 6-1 Retail) ..................................................... 6-6 Table 6-2. Wastewater Collected Within Service Area in 2025 (DWR Table 6-2 Retail) ..................... 6-7 Table 6-3. Wastewater Treatment and Discharge Within Service Area in 2025 (DWR Table 6-3 Retail) ...................................................................................................... 6-9 Table 6-4. Recycled Water Direct Beneficial Uses Within Service Area (DWR Table 6-4 Retail) ...... 6-12 Table 6-5. 2020 UWMP Recycled Water Use Projection Compared to 2025 Actual (DWR Table 6-5 Retail) .................................................................................................... 6-13 Table 6-6. Methods to Expand Future Recycled Water Use (DWR Table 6-6 Retail) ........................ 6-13 Table 6-7. Expected Future Water Supply Projects or Programs (DWR Table 6-7 Retail) ................ 6-14 Table 6-8. Water Supplies – Actual (DWR Table 6-8 Retail) .............................................................. 6-18 Table 6-9. Water Supplies – Projected (DWR Table 6-9 Retail) ......................................................... 6-19 Table 6-10. Recommended Energy Reporting - Total Utility Approach (DWR Table O-1B) .............. 6-22 Table 7-1. Estimated Local Reservoir Yields ........................................................................................ 7-4 Table 7-2. Estimated Local Reservoir Annual Depletion ..................................................................... 7-5 Table 7-3. Basis of Water Year Data – Local Surface Water (DWR Table 7-1 Retail) .......................... 7-6 Table 7-4. State Water Project Reliability Assumptions ...................................................................... 7-7 Table 7-5. Basis of Water Year Data – State Water Project (DWR Table 7-1 Retail) ........................... 7-8 Table 7-6. Normal Year Supply and Demand Comparison (DWR Table 7-2 Retail) ............................. 7-9 Table 7-7. Single Dry Year Supply and Demand Comparison (DWR Table 7-3 Retail)......................... 7-9 Table 7-8. Multiple Dry Years Supply and Demand Comparison (DWR Table 7-4 Retail) ................. 7-10 Table 7-9. Projected Supplies for Drought Risk Assessment ............................................................. 7-11 Table 7-10. Five-Year Drought Risk Assessment (DWR Table 7-5 Retail) .......................................... 7-12 Table 9-1. City of Napa Current Water Rate Schedule ........................................................................ 9-4 Table 10-1. Notification to Cities and Counties (DWR Table 10-1 Retail) ......................................... 10-2

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
vii City of Napa
2025 Urban Water Management Plan
May 2026

Table of Contents

LIST OF FIGURES
Figure ES-1. City of Napa Water System Boundaries ........................................................................ ES-3 Figure 3-1. City of Napa Vicinity .......................................................................................................... 3-1 Figure 3-2. City of Napa Water System Boundaries ............................................................................ 3-2 Figure 3-3. City of Napa Water Treatment and Distribution System .................................................. 3-5 Figure 3-4. City of Napa Water Division Organization ......................................................................... 3-6 Figure 6-1. Napa Sanitation District Recycled Water Pipelines ......................................................... 6-10 Figure 7-1. Lake Hennessey Storage During 1987-1992 Drought ....................................................... 7-4

LIST OF APPENDICES
Appendix A. Urban Water Management Planning Act Legislative Requirements Appendix B. Demonstration of Reduced Delta Reliance
Appendix C. DWR 2025 Urban Water Management Plan Tables Appendix D. DWR 2025 Urban Water Management Plan Checklist Appendix E. Agency and Public Notices
Appendix F. Distribution System Water Loss Audits
Appendix G. SB X7-7 Compliance Tables
Appendix H. Recycled Water Sales Agreement
Appendix I. Napa Sanitation District Recycled Water Policy (Resolution No. 22-020) Appendix J. Water Shortage Contingency Plan
Appendix K. UWMP and WSCP Adoption Resolutions

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May 2026

Table of Contents

LIST OF ACRONYMS AND ABBREVIATIONS
°F Fahrenheit 3-9
2020 Target 2020 Urban Water Use Target 5-1
AB Assembly Bill 1-1
ABAG Association of Bay Area Governments 3-9
Act Urban Water Management Planning Act 1-1
AF Acre-Feet 2-1
AFY Acre-Feet Per Year 2-1
American Canyon City of American Canyon 3-3
AMI Advanced Metering Infrastructure 6-4
AMP Asset Management Plan 9-7
AMR Automatic Meter Reading 9-2
AWWA American Water Works Association 4-6
Barwick Jamieson
BiOps
Edward I. Barwick Jamieson Canyon
Biological Opinions
7-1
BMP Best Management Practices 9-19
CALGreen California Green Building Standards Code 4-7
Calistoga City of Calistoga 3-3
CalWEP California Water Efficiency Partnership 9-1
CAP Climate Action Plan 4-1
CFD Community Facility District 9-17
cfs Cubic Feet Per Second 6-4
CII Commercial, Industrial, and Institutional 9-6
CIMIS California Irrigation Management Information System 3-8 City City of Napa 1-1
City Council Napa City Council 1-4
County Napa County 2-4
CVWD Congress Valley Water District 3-3
CWC California Water Code 1-1
DCP Drought Contingency Plan 6-15
DDW Division of Drinking Water 7-3
Delta Sacramento-San Joaquin Delta 1-3
Division City of Napa Water Division 3-6
DMMs Demand Management Measures 9-1
DOF California Department of Finance 3-9
DRA Drought Risk Assessment 1-2
Draft 2025 DCR Draft State Water Project Delivery Capability Report (December 2025) DWR California Department of Water Resources 1-2
DWR Guidebook Urban Water Management Plan Guidebook 2025 1-4 DWR’s
Methodologies
DWR’s Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use (2016)
5-1
EIR Environmental Impact Report 3-6
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Table of Contents
EPA Environmental Protection Agency 9-7
ERTs Encoder Receiver Transmitters 9-2
ET Evatranspiration 3-4
ETo Evapotranspiration 3-8
FTE Full-time Equivalents 9-13
GHG Greenhouse Gas 3-9
GP General Plan 6-5
GPCD Gallons Per Capita Per Day 5-1
gpf Gallons Per Flush 9-7
GSA Groundwater Sustainability Agency 1-2
GSP Groundwater Sustainability Plan ES3 / 1-2
HCD Housing and Community Development 3-12
HECWs High-Efficiency Clothes Washers 9-8
HETs High-Efficiency Toilets 9-7
HEUs High-Efficiency Urinals 9-8
HMP Hazard Mitigation Plan 8-1
hp
HRL
Horsepower
Healthy Rivers and Landscapes
6-7
ILI Infrastructure Leakage Index 9-12
KCWA Kern County Water Agency 6-1
kWh Kilowatt-Hours 6-17
LAFCO Local Agency Formation Commission of Napa County 3-3 LCWD Los Carneros Water District 6-8
M&I Municipal & Industrial 4-1
MC Municipal Code 6-12
MCL Maximum Contaminant Levels 7-3
MG Million Gallons 3-3
MGD Million Gallons Per Day 3-3
MST Milliken-Sarco-Tulocay 6-8
MTC Metropolitan Transportation Commission 3-11
MWELO Model Water Efficient Landscape Ordinance 4-7
NAICS North American Industry Classification System 4-1 NapaSan Napa Sanitary District 4-1
NBA North Bay Aqueduct 3-3
NCFCWCD Napa County Flood Control and Water Conservation District 2-2 NMC Napa Municipal Code 4-7
NOD North of Delta 6-2
NPDES National Pollutant Discharge Elimination System 7-4 O&M Operations & Maintenance 9-7
POU Place of Use 6-6
psi Pounds Per Square Inch 6-8
QWEL Qualified Water Efficiency Landscaper 9-3
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Table of Contents
RHNA Regional Housing Needs Allocation 3-12
RUL Rural Urban Limit 3-1
RUWMP Regional Urban Water Management Plan 2-1
SB Senate Bill 1-1
SB X7-7 Water Conservation Act of 2009 ES1 / 1-1
SCADA Supervisory Control and Data Acquisition 9-1
SGMA Sustainable Groundwater Management Act 1-2
SOD
SOI
South of Delta
Sphere of Influence

St. Helena City of St. Helena 3-3
State Water Board State Water Resources Control Board 6-7 SWP State Water Project 1-3
TDS Total Dissolved Solids 7-3
ULFTs Ultra-Low-Flush Toilets 9-7
USBR United States Bureau of Reclamation 7-2
USEPA U.S. Environmental Protection Agency 7-3
UWMP Urban Water Management Plan 1-1
UWUO Urban Water Use Objectives 9-18
Valley Water Santa Clara Valley Water District 6-13
WET Water Education for Teachers 9-5
WRF Water Recycling Facility 6-6
WSA Water Supply Agreement 6-1
WSCP Water Shortage Contingency Plan 1-1
WTP Water Treatment Plant 3-3
WUE Water Use Efficiency 10-3
Yountville Town of Yountville 3-3

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
ES-1 City of Napa
2025 Urban Water Management Plan
May 2026

Executive Summary

INTRODUCTION
An Urban Water Management Plan (UWMP , plan) helps water suppliers assess the availability of their water supplies with current and projected water use to help ensure reliable water service under different conditions. This water supply planning is especially critical for California as climate chang e alters rainfall and snowfall patterns (impacting water supply availability) and development continues to occur statewide (increasing the need for reliable water supplies). The Urban Water Management Planning Act (Act) requires larger water suppliers that provide water to urban users (whether directly or indirectly) to develop UWMPs every five years. UWMPs evaluate conditions for the next 20 to 25 years, so these regular updates ensure continued, long-term water supply planning.

The City of Napa (City) sells and distributes treated water to individual water users ( e.g., residences and businesses). Because the City provides water to more than 3,000 customers, it is required to prepare an UWMP.

This Executive Summary serves as a Lay Description of the City of Napa 's 2025 UWMP, as required by California Water Code § 10630.5.

CALIFORNIA WATER CODE REQUIREMENTS
The California Water Code (CWC) documents specific requirements for California water suppliers. The Act is included in the CWC and specifies the required elements of an UWMP, including discussing an agency’s water system and facilities, calculating how much water its customers use ( i.e., water demand) and how much it can supply, and detailing how it would respond during a drought or other water supply shortage.

Also, an UWMP must describe what specific coordination steps were taken to prepare, review, and adopt the plan.

The Act has been revised over the years. The Water Conservation Act of 2009 (also known as SB X7-7) required retail water agencies to establish water use targets for 2015 and 2020 that would result in statewide water savings of 20 percent by 2020. In their 2025 UWMPs, retail water agencies are required to report on their compliance with SB X7-7 2020 water use targets.

The 201 2 to 201 6 drought led to further revisions to the Act to improve water supply planning for long-term reliability and resilience to drought and climate change. These revisions were formalized in the 2018 Water Conservation Legislation and include:
• Five Consecutive Dry-Year Water Reliability Assessment: Analyze water supply reliability for five consecutive dry years over the planning period of this plan (see Chapter 7). • Drought Risk Assessment: Assess water supply reliability for the next five years assuming they are dry years (see Chapter 7).
• Seismic Risk: Identify the seismic risk to the agency’s water facilities and have a plan to address identified risks (see Chapter 8).
• Energy Use Information: If data are available, include reporting on the amount of electricity used to obtain, treat, and distribute water (see Chapter 6).

ATTACHMENT 3

Executive Summary

N-C-424-60-26-28-WP-R-25-UWMP
ES-2 City of Napa
2025 Urban Water Management Plan
May 2026

• Water Shortage Contingency Plan (WSCP): Update the agency’s plan to include an annual process for assessing potential gaps between planned water supply and demands; conform with the State’s standard water shortage levels (including a shortage level greater than 50 percent) for consistent messaging and reporting; and provide water shortage responses that are locally appropriate (see Chapter 8).
• Lay Description: Provide a lay description of the findings of the UWMP; this Executive Summary serves as the “Lay Description” for this plan.

Major components and findings of the City’s 2025 UWMP are summarized below.

CITY WATER SYSTEM
The City serves drinking water to an area encompassing much of the lower Napa Valley and extending up to the foothills on the east and west sides of the valley as shown on Figure ES-1. In addition, the City exports water to the City of American Canyon, the City of St. Helena, the City of Calistoga, the Town of Yountville, and the Veterans Home of California. Because deliveries to the City of American Canyon and City of Calistoga do not directly impact the City’s water supply, they are fully excluded from the water service reliability (supply vs. demand) analyses of this plan.

The Water Division of the City Utilities Department is responsible for the operation, maintenance, and improvement of the municipal drinking water system owned by the City. The City’s municipal drinking water system consists of 3 water treatment plants, 15 storage tanks, 10 pump stations, and approximately 360 miles of pipelines (including hydrant laterals).

WATER USE BY CITY CUSTOMERS
The City anticipates moderate growth in the next 25 years, which would increase its demand for water.

Thorough and accurate accounting of current and future water demands is critical for the City’s planning efforts. To continue delivering reliable drinking water, the City must know how much water its customers currently use and how much they expect to use in the future.

The City reviewed development and planning documents to estimate water demands through the year 2050.

Overall, the City’s water demand could potentially increase by approximately 20 percent (from 2025 levels) by 2050.

Some of the potential growth in water demand is offset by increased recycled water use and improved overall water use efficiency. Recycled water is municipal wastewater that has been treated to a specified quality that allows for reuse . Napa Sanitation District provides recycled water within the City’s water service area, mainly for irrigation. Although recycled water use within the City’s service area was less than 4 percent of the City’s total water use in 2025, the City expects the volume of recycled water use to nearly double by 2050.

ATTACHMENT 3

Executive Summary

N-C-424-60-26-28-WP-R-25-UWMP
ES-3 City of Napa
2025 Urban Water Management Plan
May 2026

Figure ES-1. City of Napa Water System Boundaries

ATTACHMENT 3

Executive Summary

N-C-424-60-26-28-WP-R-25-UWMP
ES-4 City of Napa
2025 Urban Water Management Plan
May 2026

CITY WATER SUPPLIES
The City’s water supplies consist of local surface water (Lake Hennessey and Milliken Reservoir) and imported water from the State Water Project (SWP), which diverts water from the Sacramento-San Joaquin Delta and conveys it to Napa and Solano counties via the North Bay Aqueduct. In 2025, approximately 73 percent of the City’s drinking water supplies came from local sources (which include Lake Hennessey and Milliken Reservoir), with the remainder coming from the SWP.

The City’s potential future water supply projects include treatment plant improvements, increasing storage through projects such as the Lake Hennessey spillway improvements and potential participation in regional storage ( e.g., Sites Reservoir) , and investigating the use of highly treated wastewater as drinking water (i.e., direct potable reuse). These projects are preliminary, so this plan does not quantify their potential impact. Therefore, the City’s projected future water supply sources remain the same: local supply from Lake Hennessey and Milliken Reservoir and imported water from the SWP. Beginning in 2045, this plan assumes an 11 percent reduction in average supplies from its local water supply sources to match the future reductions projected for the SWP due to climate change.

The State Water Resources Control Board is updating the Bay -Delta Plan, with early analyses showing potential reductions in SWP allocations under the Unimpaired Flow approach, especially in critically dry years. Napa County cities, Napa County Flood Control and Water Conservation District, and the State Water Contractors support the alternative Healthy Rivers and Landscapes (HRL) approach, which balances environmental and water supply needs. Because the HRL approach is expected to be adopted in 2026, this UWMP does not include Unimpaired Flow-related curtailments; future UWMP updates will address any finalized Bay-Delta Plan impacts.

CONSERVATION TARGET COMPLIANCE
In its 2015 UWMP, the City documented meeting its interim water use target and confirmed its 2020 water use target based on 2010 Census data. In 2020, the City was on track to meet its 2020 water use target, but the COVID-19 pandemic and dry conditions increased water use slightly above the target. In 2025, the City’s per capita water use easily met the City’s 2020 water use target.

CITY WATER SERVICE RELIABILITY
Under normal hydrological conditions, the City's existing water supplies are sufficient to meet future projected demands. The CWC also asks agencies to evaluate their water service reliability by examining the impact of drought on their water supplies and comparing those reduced supplies to water demands.

Specifically, agencies should calculate their water supplies during a single dry year and five consecutive dry years using historical records. For example, the City can estimate its supply during a single dry year by looking at how much local surface water was available during the driest year on record. If the historical “dry year” supply was reduced by 10 percent, then the City can conservatively assume a similar 10 percent reduction in its supplies during a future dry year.

The City is positioned to withstand the effects of a single dry year and a five -year drought. No supply shortfalls are projected for single dry years through 2050. The City is projected to experience supply shortfalls of up to 16 to 18 percent in multiple dry years starting in 2045 and 2050, respectively; however, these shortfalls could be managed via demand reduction measures in Stage 2 of the City’s WSCP and/or dry year water supply purchases.

ATTACHMENT 3

Executive Summary

N-C-424-60-26-28-WP-R-25-UWMP
ES-5 City of Napa
2025 Urban Water Management Plan
May 2026

Drought risk was also specifically assessed assuming 2026 through 2030 would be dry years; however, no supply shortfalls are projected.

WATER SHORTAGE CONTINGENCY PLAN
A WSCP describes an agency’s plan for preparing for and responding to water shortages. The WSCP includes a process for assessing potential gaps between planned water supply and demands for the current year and the following (assumed dry) year. The City ’s water shortage levels are aligned with the State’s standard stages for consistent messaging and includes locally appropriate water shortage responses. The WSCP may be used for foreseeable and unforeseeable events and is adopted concurrently with this plan by separate resolution to allow for updates as conditions change. Only minor refinements were made to the WSCP as part of this plan.

UWMP PREPARATION, REVIEW, AND ADOPTION
The City prepared this 2025 UWMP and WSCP in coordination with the public. While preparing this plan, the City also notified other stakeholders ( e.g., Napa County, City of American Canyon , Napa Sanitation District, etc.) of its preparation, its availability for review, and the public hearing prior to adoption. The City encouraged community participation in the review of the 2025 UWMP and WSCP using newspaper notices, the City’s weekly e -newsletter, social media posts, and the City’s website. These public no tices included the time and place of the public hearing, as well as where the plan would be available for public inspection.

The public hearing provided an opportunity for the City’s water users and the general public to become familiar with the 2025 UWMP and WSCP and ask questions about the City’s plans for continuing to provide a reliable, high -quality, essential drinking water supply and mitigating potential water shortages.

Following the public hearing, the Napa City Council adopted this 2025 UWMP and WSCP on June 16, 2026.

A copy of the adopted UWMP was submitted to the Department of Water Resources and is available on the City’s website: cityofnapa.org/water.

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
1-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 1
Introduction
This chapter provides an introduction and overview of the City of Napa’s (City) 2025 Urban Water Management Plan (UWMP, plan), including the importance and extent of the City’s water management planning efforts, changes since the preparation of the 2020 UWMP, and the organization of this 2025 UWMP. This plan has been prepared jointly by City staff and West Yost.

1.1 INTRODUCTION
The Urban Water Management Planning Act (Act) was originally established by Assembly Bill (AB) 797 on September 21, 1983. In passing the Act, state legislators recognized that water is a limited resource and declared that efficient water use and conservation would be actively pursued throughout the State. The primary objective of the Act is to direct “urban water suppliers” to develop a n UWMP that provides a framework for long-term water supply planning and documents how urban water suppliers are carrying out their long-term resource planning responsibilities to ensure adequate water supplies are available to meet existing and future water demands. A copy of the current version of the Act, as incorporated in Section 10608 and Sections 10610 through 10656 of the California Water Code (CWC), is provided in Appendix A of this plan.

1.2 IMPORTANCE AND EXTENT OF CITY’S WATER MANAGEMENT PLANNING

EFFORTS
The purpose of the UWMP is to provide a planning tool for the City to develop, manage, and deliver municipal water supplies to its water service area. The Water Shortage Contingency Plan (WSCP) is part of this UWMP and provides a plan for response to various water supply shortage conditions.

To continue to meet the water needs of the community, the City carefully manages their available water resources. This plan provides the City with a comprehensive water management action plan for guidance as water supply and demand conditions change.

1.3 CHANGES FROM 2020 UWMP
The Act has been modified over the years in response to the State’s water shortages, droughts, and other factors. A significant amendment was made in 2009, after the 2007 to 2009 drought, and as a result of the Governor’s call for a statewide 20 percent reduction in urban water use by the year 2020. This was the Water Conservation Act of 2009, also known as Senate Bill Seven of the Senate’s Seventh Extraordinary Session of 2009 (SB X7-7). The Water Conservation Act of 2009 required agencies to establish water use targets for 2020 that would result in statewide water savings of 20 percent by 2020.

The City is required to report compliance with its 2020 water use target in its 2025 UWMP.

The 2012 to 2016 drought led to further amendments to the CWC to improve water supply planning for long-term reliability and resilience to drought and climate change. The 2018 Water Conservation Regulation for Making Conservation a California Way of Life (AB 1668 [Friedman] and SB 606 [Hertzberg]) required major additions and changes to the CWC. These changes are associated with managing drought preparedness and water shortage contingency planning for urban water suppliers.

ATTACHMENT 3

Chapter 1
Introduction

N-C-424-60-26-28-WP-R-25-UWMP
1-2 City of Napa
2025 Urban Water Management Plan
May 2026

No substantive changes to the requirements have been adopted since the completion of the City’s 2020 UWMP. This 2025 UWMP builds on the planning and reporting provided in the City’s 2020 UWMP.

Key updates include:
• Water Supply Reliability Assessment – a water supply and demand assessment which compares the total water supply sources available to the City with the long-term total projected water use over the next 25 years (to 2050), in five-year increments, for a normal water year, a single dry water year, and a drought lasting five consecutive water years (CWC §10635(a))
• Drought Risk Assessment – an assessment of the City’s water supply reliability assuming that the Years 2026 to 2030 will be the five consecutive dry years (CWC §10635(b)) • Water Use Target Compliance – compliance with the City’s previously adopted 2020 per capita water use targets in accordance with SB X7-7 (Water Conservation Act of 2009, SB X7-7; CWC §10608.20)
• Water Loss Quantification – a summary report quantifying the City’s system water loss for Years 2020 to 2024, and progress toward compliance with the City’s Water Loss Standard as established by the State Water Resources Control Board (State Water Board) (CWC §10631(d)(3)(c))
Since the completion of the City’s 2020 UWMP, the State experienced another multi -year (2021 – 2023) drought event during which the City implemented its WSCP. This UWMP includes minor updates to the City’s WSCP to incorporate lessons learned from that event, as discussed in Chapter 8.

1.4 DEMONSTRATION OF CONSISTENCY WITH THE DELTA PLAN FOR

PARTICIPANTS IN COVERED ACTIONS
Urban water suppliers that anticipate participating in or receiving water from a proposed project (i.e., “covered action”), such as a multi -year water transfer, conveyance facility, or new diversion that involves transferring water through, exporting water from, or using water in the Sacramento-San Joaquin Delta (Delta) should provide information in their UWMP that can then be used in the certification of consistency process to demonstrate consistency with Delta Plan Policy WR P1, Reduce Reliance on the Delta Through Improved Regional Water Self-Reliance (California Code of Regulations, Title 23, Section 5003).

To demonstrate reduced reliance on the Delta and improved regional self-reliance, urban water suppliers are to:

1. Complete an UWMP.

2. Identify, evaluate, and commence implementation of programs and projects included in the UWMP that are locally cost effective and technically feasible in reducing reliance on the Delta.

3. Include expected outcome for measurable reduction in Delta reliance and improvement in regional self-reliance in their UWMPs, commencing in their 2015 UWMPs and continuing in their subsequent UWMPs. Programs and projects identified above should reduce the amount or percentage of water used from the Delta watershed. For the purposes of reporting, water use efficiency is considered a new source of water supply.

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Chapter 1
Introduction

N-C-424-60-26-28-WP-R-25-UWMP
1-3 City of Napa
2025 Urban Water Management Plan
May 2026

Since the City is a subcontractor of the State Water Project (SWP), it anticipates participating in covered actions and is therefore required to demonstrate reduced Delta reliance. Appendix B of this plan demonstrates the City’s consistency with Delta Plan Policy WR P1.

Chapter 6 of this UWMP describes and evaluates existing and future projects whose implementation improves regional self-reliance. Chapter 9 of this UWMP describes Demand Management Measures that the City has implemented as part of its water use efficiency and conservation programs.

1.5 PLAN ORGANIZATION
This plan contains the appropriate sections and tables required per CWC Division 6, Part 2.6 (Act), included in Appendix A of this plan, and has been prepared based on guidance provided by DWR in their “ Urban Water Management Plan Guidebook 2025” (DWR Guidebook).

This plan is organized into the following chapters:
• Chapter 1: Introduction
• Chapter 2: Plan Preparation
• Chapter 3: Service Area Description
• Chapter 4: Water Use Characterization
• Chapter 5: SB X7-7 Baselines, 2020 Targets, and 2025 Reporting • Chapter 6: Normal-Year Water Supply Characterization
• Chapter 7: Water Service Reliability and Drought Risk Assessment • Chapter 8: Water Shortage Contingency Plan
• Chapter 9: Demand Management Measures
• Chapter 10: Plan Adoption, Submittal, and Implementation This plan also contains the following appendices of supplemental information and data:
• Appendix A: Legislative Requirements
• Appendix B: Demonstration of Reduced Delta Reliance
• Appendix C: DWR 2025 Urban Water Management Plan Tables • Appendix D: DWR 2025 Urban Water Management Plan Checklist • Appendix E: Agency and Public Notices
• Appendix F: Distribution System Water Loss Audits
• Appendix G: SB X7-7 Compliance Tables
• Appendix H: Recycled Water Sales Agreement
• Appendix I: Napa Sanitation District Recycled Water Policy (Resolution No. 22-020) • Appendix J: Water Shortage Contingency Plan
• Appendix K: UWMP and WSCP Adoption Resolutions
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Chapter 1
Introduction

N-C-424-60-26-28-WP-R-25-UWMP
1-4 City of Napa
2025 Urban Water Management Plan
May 2026

Furthermore, this plan contains all the tables recommended in the DWR Guidebook, both embedded into each chapter where appropriate and included in Appendix C.

DWR’s U WMP Checklist, as provided in the DWR Guidebook, has been completed by West Yost to demonstrate the plan’s compliance with applicable requirements. A copy of the completed checklist is included in Appendix D.

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
2-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 2
Plan Preparation
This chapter describes the preparation of the City’s 2025 UWMP and WSCP, including the basis for preparing the plan, individual or regional planning, fiscal or calendar year reporting, units of measure, and plan coordination and outreach.

2.1 BASIS FOR PREPARING A PLAN
The Act requires every “urban water supplier” to prepare and adopt a n UWMP and review its plan at least once every five years to make any amendments or changes that are identified by the review. The Act also requires every “urban water supplier” to prepare and periodically update its W SCP. While the WSCP is part of the UWMP, it may be adopted and amended separately from the UWMP. An urban water supplier is defined as a supplier, either publicly or privately owned, providing water for municipal purposes either directly or indirectly to more than 3,000 customers or supplying more than 3,000 acre-feet of water per year (AFY).

The City manages Public Water System CA2810003. As shown in Table 2-1, the City provided water to 25,500 customer connections and supplied 12,211 acre-feet (AF) of water in 2025. Therefore, the City is required to prepare an UWMP, as it meets the definition of an urban water supplier.

While the City treats and wheels water to the cities of American Canyon and Calistoga, it is not considered a wholesale supplier for UWMP purposes since the City provides less than 3,000 AFY of potable water at wholesale for municipal use. The City’s last UWMP, the 2020 UWMP, was adopted by the City Council on December 21, 2021.

Table 2-1. Public Water Systems (DWR Table 2-1 Retail)

2.2 REGIONAL PLANNING
As described in Section 2.3 below, the City has prepared this plan on an individual reporting basis, not part of a regional planning process.

CA2810003 City of Napa 25,500 12,211
25,500 12,211
NOTES: Volumes are in acre-feet (AF). Excludes 799 AF treated & wheeled to the cities of American Canyon and Calistoga, as those agencies provide the source of supply.

Volume of Water
Supplied 2025 (AF)
Total
Public Water System
Number
Public Water System
Name
Number of Municipal
Connections 2025
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Chapter 2
Plan Preparation

N-C-424-60-26-28-WP-R-25-UWMP
2-2 City of Napa
2025 Urban Water Management Plan
May 2026

2.3 INDIVIDUAL OR REGIONAL PLANNING AND COMPLIANCE
As shown in Table 2-2, this plan has been prepared on an individual reporting basis covering only the City’s water service area. The City does not participate in a regional alliance, and it has not prepared a Regional Urban Water Management Plan. As described in Section 2.5, the City has notified and coordinated planning and compliance with appropriate regional agencies and constituents.

Table 2-2. Plan Identification (DWR Table 2-2)

2.4 FISCAL OR CALENDAR YEAR AND UNITS OF MEASURE
The City is a water retailer and has prepared its 2025 UWMP on a calendar year basis, with the calendar year starting on January 1 and ending on December 31. Water use and planning data for the entire 2025 calendar year have been included. Water volumes in this plan are reported in units of AF.

The City’s reporting methods for this plan are summarized in Table 2-3.

Table 2-3. Supplier Identification (DWR Table 2-3)

Select
One
Name of Regional Alliance or
RUWMP (Drop Down List)Type of Plan
Individual UWMP
If Water Supplier is also a member of a SB X7-7
Regional Alliance, select name from the drop-down.

Regional Urban Water Management Plan (RUWMP)
If Supplier selected RUWMP, select name from the
drop-down.

Supplier is a wholesale supplier
Supplier is a retail supplier
UWMP Tables are in calendar years
UWMP Tables are in fiscal years
Unit AF
Type of Supplier (select one or both)
Fiscal or Calendar Year (select one)
If using fiscal years provide month and date that the fiscal year begins (mm/dd)
Units of measure used in UWMP
(Select from the drop down list).

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Chapter 2
Plan Preparation

N-C-424-60-26-28-WP-R-25-UWMP
2-3 City of Napa
2025 Urban Water Management Plan
May 2026

2.5 COORDINATION AND OUTREACH
This section discusses the City’s inter -agency coordination and coordination with the public. The Act requires the City to coordinate the preparation of its UWMP and WSCP with other appropriate agencies and departments within the City, including other water suppliers that share a common source, water management agencies, and relevant public agencies. These agencies, as well as the public, participated in the coordination and preparation of the City’s 2025 UWMP and WSCP and are summarized below.

2.5.1 Wholesale and Retail Coordination
The Napa County Flood Control and Water Conservation District (NCFCWCD) contracts directly with DWR for SWP supplies. The City receives its annual SWP entitlement through this contract as a SWP subcontractor. In this way, NCFCWCD is a “wholesaler” for the City, as shown in Table 2-4.

In accordance with CWC Section 10631, the City has informed NCFCWCD of its projected SWP use and overall water use in five year increments through 2050. As part of its management of the SWP contract, NCFCWCD provides continual updates to the City regarding SWP supply outlook based on current and future hydrological conditions and the anticipated impact of State Water Board actions.

Table 2-4. Water Supplier Information Exchange (DWR Table 2-4 Retail)

2.5.2 Coordination with Other Agencies and the Community The City coordinated the preparation of this plan with other departments within the City as well as other local agencies, including relevant public agencies that utilize the same water supplies. These agencies included:
• City of American Canyon
• Town of Yountville
• Veterans Home of California
• City of St. Helena
• City of Calistoga
• Napa Sanitation District
• Napa County

The retail Supplier has informed the following wholesale supplier(s) of projected water use.

Wholesale Water Supplier Name
Napa County Flood Control and Water Conservation District (NCFCWCD) NOTES: NCFCWCD is the direct local contractor with DWR for State Water Project (SWP) supplies. In this way it acts as a wholesaler to the City, a SWP subcontractor.

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Chapter 2
Plan Preparation

N-C-424-60-26-28-WP-R-25-UWMP
2-4 City of Napa
2025 Urban Water Management Plan
May 2026

The City actively encourages community participation in water management activities and specific water-related projects. The City’s public participation program includes both active and passive means of obtaining input from the community, such as mailings, public meetings, and web -based communication.

The City’s website describes ongoing projects and posts announcements of planned rate increases to fund water projects.

As part of the 2025 UWMP and WSCP development, the City facilitated a public review period. Public noticing, pursuant to Section 6066 of the Government Code, was conducted prior to commencement of a public comment period. Public hearing notices are included in Appendix E of this plan. During the public comment period, the Draft UWMP and WSCP were made available on the City’s website (cityofnapa.org/water) and at the Utilities Department, City Hall, and the Napa County Library.

The public hearing provided an opportunity for City water users and the general public to become familiar with the 2025 UWMP and WSCP and ask questions about the City’s water supply and demand and its continuing plans for providing reliable, high -quality, essential drinking water to ensure quality of life for the community.

2.5.3 Notice to Cities and Counties
CWC Section 10621(b) requires agencies to notify the cities and counties to which they serve water at least 60 days in advance of the public hearing that the UWMP and WSCP are being updated and reviewed.

In March 2026 , notice s of preparation w ere sent to these cities, Napa County (County), and other stakeholders to inform them of the UWMP and WSCP update process and schedule, and to solicit input for the 2025 UWMP and WSCP. The notifications to cities and counties, the public hearing notifications, and the public hearing and adoption are discussed in Chapter 10 of this plan.

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
3-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 3
Service Area Description
This chapter describes the City’s water service area , system facilities, and staff. In addition, this chapter discusses the climate, population, demographics, and land use within the City’s service area.

3.1 GENERAL DESCRIPTION
The City is located at the northern end of San Pablo Bay, approximately 40 miles northeast of San Francisco, as shown on Figure 3-1. Incorporated in 1872, the City is the county seat for Napa County and the dynamic, vibrant hub of the idyllic Napa Valley. Famous for its wineries, Napa offers an incredible combination of suburban amenities, rural beauty, and the urban benefits of being only one hour from San Francisco and the Pacific Ocean. The City's historic character, natural beauty, and unique attractions have enabled it to become a quality residential community, as well as one of the nation's premier tourist destinations.

Figure 3-1. City of Napa Vicinity

3.2 SERVICE AREA DESCRIPTION
The City serves drinking water to an area encompassing much of the lower Napa Valley and extending up to the foothills on the east and west sides of the valley. As shown on Figure 3-2, the City’s water system contains two boundaries of importance: Water Operational Areas and Water System Service Area.

ATTACHMENT 3

Chapter 3
Service Area Description

N-C-424-60-26-28-WP-R-25-UWMP
3-2 City of Napa
2025 Urban Water Management Plan
May 2026

Figure 3-2. City of Napa Water System Boundaries
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Chapter 3
Service Area Description

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2025 Urban Water Management Plan
May 2026

The Water Operational Areas encompass the City’s Water System Service Area in addition to its reservoirs and watersheds (Lake Hennessey, Milliken Reservoir), Water T reatment Plants (WTPs) (Hennessey, Milliken, and Edward I. Barwick Jamieson Canyon [Barwick Jamieson]), and transmission mains originating from the WTPs.

While most of the City’s water supply is delivered to customers within the City limits, the City also serves water outside City limits and even outside the Sphere of Influence ( SOI), including customers in the Monticello Road/Silverado Resort community, the geographical areas that comprise the Congress Valley Water District (CVWD), the Carneros Mutual Water Company, and along the Conn Transmission Main.

CVWD was originally scheduled to be dissolved in 2017, with its water system infrastructure wholly maintained by and transferred to the City; however, after four amendments to the original agreement, it was replaced in 2023 with a 20 -year agreement that clarifies terms and responsibilities of each party through January 31, 2043 . The City also serves approximately 1,175 residents of Napa State Hospital located outside the City limits.

No significant changes impacting the City’s service area have occurred since the 2020 UWMP. The last significant change occurred in 2014, when the City Council approved the annexation of the 151-acre parcel known as the “Napa Pipe Property,” located at the south end of the City on the eastern bank of the Napa River.

The City also exports water to the City of American Canyon (American Canyon), the City of St. Helena (St. Helena), the City of Calistoga (Calistoga), the Town of Yountville (Yountville), and the Veterans Home of California in Yountville . Calistoga has contractual entitlements to SWP water from the North Bay Aqueduct (NBA), and the City treats their water at its Barwick Jamieson WTP and wheels it to them.

American Canyon also receives treat and wheel services for their SWP entitlements at times, for example each spring when the NBA is offline for routine annual maintenance. Because deliveries to Calistoga and American Canyon do not directly impact the City’s supply, they are fully excluded from the water service reliability (supply vs. demand) analyses in Chapter 7 of this plan. St. Helena and Yountville are also “wholesale” customers of the City, as any City water they purchase is then sold to their own retail customers (i.e., end users). St. Helena is contractually obligated to purchase 600 AF of water each year from the City and has the option to request an additional 200 AF of supply. Yountville and the Veterans Home of California rarely purchase water from the City due to their own sufficient local water supply sources. By agreement, the City provides water to Yountville in emergencies to address infrastructure failure or for temporary planned maintenance, but not drought needs.

3.3 WATER SYSTEM DESCRIPTION
Figure 3-3 shows the major components of the City’s potable water system, including the Conn Transmission Main and the Hennessey, Milliken, and Barwick Jamieson WTPs.

Hennessey WTP began operation in 1981 and has a nominal treatment capacity of 20 million gallons per day (MGD). Treating water from Lake Hennessey, the Hennessey WTP provides complete conventional treatment, including flash mixing, coagulation, flocculation, sedimentation, filtration, and disinfection.

Treated water from the Hennessey WTP is stored on-site in a buried , 5.0 million gallon (MG) concrete clearwell before delivery to the City’s distribution system through the 20-mile long, 36-inch diameter Conn Transmission Main. The Conn Transmission Main runs parallel to Conn Creek, Highway 128, and Highway 29, traveling along easements and rights -of-way before connecting to the City’s main water distribution system in northwest Napa and extending to East Avenue.

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Chapter 3
Service Area Description

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2025 Urban Water Management Plan
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Milliken WTP was constructed in 1976 and has a rated treatment capacity of 4 MGD, but can only produce up to 3.3 MGD of treated water. Raw water from Milliken Reservoir is released into Milliken Creek below the dam and then diverted through a 16-in diameter steel transmission pipeline to the Milliken WTP, a direct filtration plant (typically operated seasonally from the end of June to the middle of October depending on raw water turbidity and seasonal yield) with a contact/reaction tank and four horizontal, dual-media pressure filters operated in parallel. Treated water is stored in a 2.0 MG clearwell tank located above the WTP site before delivery to the City’s water distribution system through the 1.5-mile long Milliken Transmission Main. The Milliken Transmission Main, constructed in 1966, predominantly serves customers in the Silverado Resort area before connecting to the City’s main water distribution system at the intersection of Silverado Trail and Monticello Road.

All SWP raw water is delivered to the Barwick Jamieson WTP, which was originally constructed in 1968 and upgraded in 1988 and 2011 to increase its treatment capacity to 20 MGD. With the increased treatment capacity, the City can now treat 100 percent of the City’s water allocation from the SWP in a typical year. Barwick Jamieson WTP includes pre-ozonation, with conventional surface water treatment processes: rapid mixing, flocculation, sedimentation with tube settlers, gravity filtration, and disinfection.

Treated water is stored in a 5.0 MG clearwell located onsite before delivery to the City’s water distribution system through the 42-inch diameter Jamieson Transmission Main. The Jamieson Transmission Main runs parallel to Jamieson Canyon Road /Highway 12 to Highway 29, then splits into 36 -inch and 24 -inch diameter pipelines near the intersection of Highway 29 and Highway 221 and feeds the City’s main water distribution system.

The City’s main water distribution system includes 15 storage tanks, 10 pump stations, and approximately 360 miles of pipelines (including hydrant laterals).

3.4 WATER DIVISION
The Water Division (Division) of the City Utilities Department is responsible for the operation, maintenance, and improvement of the municipal drinking water system owned by the City. The City operates under a Council-Manager form of government by which the five -member City Council sets City policy and directly hires the City Manager to implement City policy. The City Manager directly hires all department heads, including the Utilities Director, and the Utilities Director hires and manages a Deputy Utilities Director to lead the Division. The mission of the Division is to provide an uninterrupted supply of high-quality and reasonably priced water to the community for consumption and fire protection.

Operating three WTPs, the Division delivers water meeting Federal and State drinking water regulations, invests in capital improvements, plans for future water supply needs, responds to emergency repairs, and maintains a proactive water conservation program. The Division operates financially as an enterprise fund, with costs paid by water rates, capacity fees, service charges, and related revenues.

As shown on Figure 3-4, the Division is organized into four sections: Administration, Water Treatment, Water Distribution, and Engineering. In 2025, there were 62 full-time employees working to meet the Division’s mission.

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Chapter 3
Service Area Description

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2025 Urban Water Management Plan
May 2026

Figure 3-3. City of Napa Water Treatment and Distribution System ATTACHMENT 3

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Figure 3-4. City of Napa Water Division Organization
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Service Area Description

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2025 Urban Water Management Plan
May 2026

3.5 SERVICE AREA CLIMATE
The climate of the City’s service area is best described as Mediterranean, characterized by hot, dry summers and cool winters . This section describes the historical climate and potential effects of climate change.

3.5.1 Historical Climate
Water use is dependent on various climate factors such as temperature, precipitation, and evapotranspiration. Relevant climate data for the City are presented in Table 3-1, including reference evapotranspiration (ETo) and average rainfall and temperatures.

ETo includes plant transpiration and water lost through evaporation from the soil and surface -water bodies. The monthly ETo totals roughly represent the irrigation needs of standard cool -season turfgrass in the City ’s water service area . Approximately 66 percent of annual ETo occurs between May and September. Since these months have the lowest rainfall totals, the higher ETo drives the demand for supplemental irrigation.

Table 3-1. Monthly Average Climate Data Summary
Month
Standard Monthly
Average ETo(a), inches
Average Total
Rainfall(b), inches
Average Temperature(b), degrees Fahrenheit
Maximum Minimum
January 2.08 5.14 57.0 38.3
February 1.86 4.38 61.5 40.8
March 3.17 3.35 65.0 42.0
April 4.71 1.65 69.6 43.7
May 7.21 0.68 74.6 47.6
June 7.21 0.21 79.8 51.3
July 7.16 0.02 81.9 53.4
August 6.93 0.06 81.7 53.2
September 4.70 0.31 82.1 51.5
October 2.82 1.36 76.5 47.9
November 1.38 2.98 65.9 42.6
December 0.87 4.50 57.6 38.8
Annual 50.1 24.7 71.1 45.9
(a) Source: 2025 California Irrigation Management Information System (CIMIS) data for Station #77: Oakville (downloaded January 22, 2026).
(b) Source: Western Regional Climate Center data for DWR for Napa State Hospital (period of record: 1893 to 2016).

There is considerable variation in precipitation from year to year . An annual total of less than 13 inches can be anticipated one year in twenty, while more than 36 inches can be expected with about the same frequency. Annual precipitation averages nearly 25 inches, but more than 80 percent of that total falls in the months of November through March, when ETo is lowest. Therefore, summer landscape irrigation is a significant component of the City’s overall water demand and has influenced the City’s water conservation efforts, which are described in Chapter 9 of this plan.

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Mild temperatures predominate in Napa, but highs above 100 degrees Fahrenheit (°F) have been observed in every month from May through October. Nights cool off quickly with the average minimum temperature during the summer months in the low 50s. Winter brings sub -freezing temperatures nearly every year. Historically, temperatures below 32°F have been recorded during each month from October through May.

3.5.2 Potential Effects of Climate Change
The CWC requires urban water suppliers to account for the impacts of climate change on water supplies and supply reliability. A discussion of the effects of climate change on water demands, supplies, and reliability can be found in Chapter 4 (Water Use Characterization), Chapter 6 (Normal-Year Water Supply Characterization), and Chapter 7 (Water Service Reliability and Drought Risk Assessment) of this plan. This section summarizes those discussions.

In general, climate change is expected to increase water demand for irrigation and the year -to-year variability of demands . This is the result of increased temperatures (which increases ET o) and more variability in precipitation (which impacts supply availability and reliability). Also, natural disasters such as wildfires, droughts, and floods are expected to increase in both frequency and intensity.

Responding to climate change generally takes two forms: mitigation and adaptation. Mitigation is taking steps to reduce the contribution to the causes of climate change by reducing greenhouse gas (GHG) emissions. Adaptation is the process of responding to the effects of climate change by modifying systems and behaviors to function in a warmer climate.

In the water sector, climate change mitigation is generally achieved by reducing energy use, increasing energy efficiency, and/or replacing fossil fuel‐based energy sources with renewable energy sources where feasible. Because water requires energy to move, treat, use, and discharge, water conservation also results in energy conservation. Adaptation initiatives may include diversification of the City’s water supply portfolio, expansion of recycled water use, and enhanced water use efficiency and conservation to better withstand drought. A comprehensive set of water-related mitigation and adaptation measures is included in the Napa County Regional Climate Action and Adaptation Plan (RCAAP), which is slated for adoption and implementation by local jurisdictions beginning in 2026.

3.6 SERVICE AREA POPULATION AND DEMOGRAPHICS

3.6.1 Service Area Population
As shown in Table 3-2, the City’s 2025 service area population is estimated to be 85,366. For its 2025 population, the City used the California Department of Finance (DOF) estimate for the population within City limits and a persons -per-connection estimate for the population served outside City limits.

Population projections for 2030 through 2050 are based on the City’s 2040 General Plan, which projects 17,900 additional residents and 7,800 new housing units by 2040. As long -range demographic and economic trends are difficult to predict and there has been a slight decrease in service area population since 2020, the full 17,900 increase has been extended out to 2050 for this plan.

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Table 3-2. Population - Current and Projected (DWR Table 3-1 Retail)

3.6.2 Other Social, Economic, and Demographic Factors
The State requires the inclusion of service area socioeconomic information as part of the system description in UWMPs. However, differences in household water use across sociodemographic groups in the City ha ve not been studied , nor does the City differentiate water management based on sociodemographic factors. Therefore, the following social, economic, and demographic information is being provided to comply with the regulation. The information was derived from the US Census Bureau’s profile of Napa for 2020-20241.
• The average number of people per household in the five-year period analyzed was 2.57. • The median household income (2024 dollars) was $105,963, while 8.5 percent of all individuals lived in poverty.
• The owner-occupied housing unit rate was 58.7 percent, with a median home value of $856,400. • The median gross rent was $2,282 per month.
• Of people 25 years or older, 84.2 percent had earned at least a high school diploma or equivalent, and 38.2 percent had earned a bachelor’s degree or higher. • Of people under 65 years of age, 8.4 percent had a disability, and 7.7 percent did not have health insurance.
• Almost 97.5 percent of households had a computer, and 93.3 percent had a broadband internet subscription.
• By race/ethnicity, 58.2 percent of people were White, 1.3 percent were Black, 1.2 percent were American Indian or Alaska Native, 3.0 percent were Asian, 0.1 percent were Native Hawaiian or Pacific Islander, and 18.5 percent were two or more races. • Of the total City population, approximately 41.2 percent were Hispanic or Latino, and

58.8 percent were not Hispanic or Latino.
• Approximately 20.9 percent of residents were foreign born, and 34.7 percent of people five years and older spoke a language other than English at home.

1 United States Census Bureau, QuickFacts Data Profile for Napa, California (https://www.census.gov/quickfacts/fact/table/napacitycalifornia/PST045224). 2025 2030 2035 2040 2045 2050(opt)
85,366 88,946 92,526 96,106 99,686 103,266
Population
Served
NOTES: 2025 calculated using California Department of Finance E-5 Estimates (May 2025) and persons-per-connection estimates. 2030-2050 projections use incremental 5-year increases derived from the current City of Napa General Plan.

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3.7 LAND USES WITHIN SERVICE AREA
Existing and future land uses within the City’s water service area are specified in its 2040 General Plan2, which the City Council adopted in 2022.

3.7.1 Current and Projected Land Uses
The City’s existing land use generally consists of a Downtown core area surrounded by residential neighborhoods. Within the City’s Planning Area (i.e., the contiguous land within City limits and the surrounding SOI), residential uses comprise approximately 49 percent of the land area. Commercial uses are concentrated along major corridors and within Downtown Napa and occupy about 8 percent of the Planning Area. Parks/open space and public facilities comprise 15 and 10 percent of the Planning Area, respectively, with agricultural (e.g., vineyards and wineries) and industrial uses making up the rest of the occupied land use. Approximately 9 percent of the land in the Planning Area is vacant.

The City also serves 47 agricultural accounts, 29 of which are interruptible services located outside City limits, primarily along the Conn Transmission Main. By agreement, these 29 services can be cut off during extreme water supply shortages.

According to the City’s 2040 General Plan, the City seeks to build upon its small -town character and historic neighborhoods while balancing the needs of residents, local businesses, and tourists. The 2040 General Plan is structured around ten Guiding Principles. The Guiding Principles most relevant to water system planning include:
• Foster Napa as a community of connected neighborhoods, with vibrant, walkable districts, and revitalized corridors.
• Promote housing and support a diverse array of housing types to meet the needs of all segments of the population.
• Promote continued Downtown revitalization.

For the City’s 2025 Water System 30 -Year Capital Improvement Master Plan, City staff provided a list of developments that could be potentially completed within the 30-year planning horizon (i.e., by 2055) to develop water demand projections. Potential developments include single- and multi-family residences, hotels/resorts, and commercial/industrial space.

3.7.2 Long-Range Land Use Planning
This section discusses long -range land use planning that may affect water management. Long -range planning includes years beyond the time horizon of this plan but should be noted for consideration in future UWMP updates.

The Association of Bay Area Governments (ABAG) and the Metropolitan Transportation Commission (MTC) completed the Plan Bay Area 2050 in October 20213, which provides long-range plans to guide the growth of the nine -county region. Plan Bay Area 2050 integrates strategies for transportation, housing, the

2 Source: https://www.cityofnapa.org/259/General-Plan.
3 An amendment was approved in November 2024 to include the Sonoma-Marin Rail Transit (SMART) passenger rail extension to Healdsburg.

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environment, and the economy. Following completion of the City’s 2040 General Plan, the City updated the Housing Element of the General Plan to plan for future housing development in the City and address the Regional Housing Needs Allocation (RHNA) by ABAG.4
Both Plan Bay Area and RHNA address the amount and location of new housing development in the region, but they are different types of planning processes. Plan Bay Area is a policy -driven land use and transportation framework that results in various projections of growth for different areas (i.e., a “ground up” model). RHNA, on the other hand, is a process whereby a pre-determined number of housing units is distributed among local jurisdictions based on factors intended to result in an equitable distribution of those units. Another key difference is that Plan Bay Area covers an approximately 30 -year planning horizon (2020-2050), whereas RHNA covers an 8-year period from 2023-2031. Despite these differences, by law, RHNA must be “consistent” with Plan Bay Area. ABAG has determined RHNA and Plan Bay Area to be consistent because the amount of housing growth from the 8-year RHNA would not exceed the 30-year growth level at the county and sub-county geographies used in Plan Bay Area.

The RHNA Plan was adopted in December 2021 and updated in June 2025 . The proposed allocation for the City, which may be subject to revision and refinement, is 2,669 housing units (including transfers from the County).5 Although the City’s RHNA allocation may not affect its long-term water demand projections, it may accelerate the rate at which demand increases in the near term.

4 ABAG receives its regional housing needs determination from the California State Department of Housing and Community Development (HCD). The nine-county San Francisco Bay Area has been allocated a total of 441,176 units, which reflects a

2.3-fold increase over the previous Housing Element cycle. 5 Association of Bay Area Governments, June 2025, Final Regional Housing Needs Allocation (RHNA) Plan: San Francisco Bay Area, 2023-2031 - Updated June 2025.

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CHAPTER 4
Water Use Characterization
This chapter describes and quantifies the City ’s past, current, and projected water use. Water demand projections are based on the projected growth from new development within the City’s water service area, along with anticipated water use efficiency improvements. Accurately tracking and reporting current water demands allows the City to properly analyze water use and better forecast future demands.

4.1 NON-POTABLE VERSUS POTABLE WATER USE
Potable water is water that is safe to drink and typically has had various levels of treatment and disinfection. The City produces potable water from local surface water supplies and water imported from the SWP via the NBA.

Non-potable water is not safe to drink and includes both recycled water and raw water. Recycled water is municipal wastewater that has been treated to a specified quality that allows for reuse. The City does not deliver recycled water to its customers; Napa Sanitation District (NapaSan) provides recycled water within the City’s water service area. Therefore, recycled water use volumes are not included in this chapter.

Raw water is untreated water that is used in its natural state or with minimal treatment. The City does not deliver raw water to any customers in its service area.

4.2 WATER USE BY SECTOR
This section describes the City’s past, current, and projected water use by sector through the year 2050.

The following classifications were used to analyze current consumption patterns among various types of customers. The City uses the same definitions for each sector as outlined in the DWR Guidebook:
• Single-family residential: A single-family dwelling unit. A lot with a free-standing building containing one dwelling unit that may include a detached secondary dwelling. • Multi-family residential: Multiple dwelling units contained within one building or several buildings within one complex.
• Commercial: A water user that provides or distributes a product or service (CWC §10608.12(d)).
• Industrial: A water user that is primarily a manufacturer or processor of materials as defined by the North American Industry Classification System (NAICS) Code Sectors 31 to 33, inclusive, or an entity that is a water user primarily engaged in research and development (CWC §10608.12(h)).
• Institutional (and Governmental): A water user dedicated to public service. This type of user includes, among other users, higher education institutions, schools, courts, churches, hospitals, government facilities, and nonprofit research institutions (CWC §10608.12(i)). • Landscape: Water connections supplying water solely for landscape irrigation. Such landscapes may be associated with multi-family, commercial, industrial, or institutional/governmental sites but are considered a separate water use sector if the connection is solely for landscape irrigation.
• Sales to other agencies: Water sales made to another agency. Projected sales may be based on projected water demand provided by the receiving agency. Since there is inherent uncertainty in future demand projections, any projected sales reported in this plan are for planning purposes only and are not considered a commitment on the part of the seller.

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• Agricultural: Water used for commercial agricultural irrigation. • Other: Any other water demand that is not adequately described by the water sectors defined above.
• Distribution System Losses: The difference between the actual volume of water treated and delivered into the distribution system and the actual metered consumption.

There are no existing water uses for saline barriers or groundwater recharge within the City’s water service area.

4.2.1 Historical Water Use
The City’s past water use by water use sector is reported in Table 4-1. These are the same values reported in the City’s 2010, 2015, and 2020 UWMPs.

Table 4-1. Historical Water Use by Sector
Water Use Sector
Actual Volume, AFY
2010 2015 2020
Single Family Residential 6,626 5,462 6,654
Multi-Family Residential 1,961 1,600 1,794
Commercial(a) 2,640 2,518 2,792
Institutional/Governmental 193 151 266
Landscape 643 739 985
Agricultural Irrigation(b) 155 195 172
Sales/Transfers/Exchanges to other agencies(c) 280 582 588 Other(d) 79 29 32
Losses(e) 1,300 758 809
Total 13,877 12,034 14,092
(a) Includes commercial, industrial, and non-City institutional uses, such as schools. (b) Interruptible-Surplus Agricultural Water Agreements with customers located outside the City limits. Annual use from these customers fluctuates based on weather conditions and the vineyards’ use of private wells and other alternative supply sources. (c) Sales to the City of St. Helena, the Town of Yountville, and the Veterans Home of California. Sales are driven primarily by Agreement No. 9381 between the City and St. Helena requiring St. Helena to purchase a minimum of 600 AFY at agreed-upon rates. Sales to Yountville and the Veterans Home of California are rare and generally limited to emergencies. (d) Includes authorized unmetered uses (e.g., water main flushing, fire protection). (e) Includes apparent and real losses.

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4.2.2 Current Water Use
The City’s actual potable water demands for the 2025 calendar year are reported in Table 4-2. Losses are estimated based on production and billing data. SWP water treated and wheeled to American Canyon and Calistoga is not included, as th ese supplies are owned by these agencies and do not impact the City’s supplies. The City’s use types are defined slightly differently than historical, now better matching the State Water Board’s Urban Drought & Conservation Reporting categories and more applicable for developing future projections.

Table 4-2. Total Uses for Potable and Non-Potable Water – Actual (DWR Table 4-1 Retail)

Use Type
Drop down list
May select each use multiple times
These are the only use types that will be
recognized by the WUEdata online submittal tool
Potable or Non-Potable
(OPTIONAL)
Drop down list
Volume (AF)
Single Family Potable 5,542
Multi-Family Potable 2,057
Commercial Commercial, non-City Institutional Potable 2,548 Industrial Potable 109
Institutional/Governmental City of Napa municipal only, excluding dedicated irrigation accounts Potable 29
Landscape Commercial, Industrial, Institutional
Dedicated Irrigation Meters (DIMs) Potable 455
Agricultural Potable 77
Sales/Transfers/Exchanges to other
Suppliers
City of St. Helena, Town of Yountville,
Veterans Home of California Potable 731
Other (optional) Hydrant flushing, firefighting, street cleaning (estimate) Potable 28
Distribution System Water Loss Real and Apparent Losses (estimate) Potable 635 12,211
0 12,211Total
NOTES: The City is a drinking water provider only and does not distribute non-potable water to customers.

DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3. 2025 Actual Water Use
Add additional rows as needed
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
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4.2.3 Projected Water Use
This section presents potable water demand projections for the City’s water service area in five -year increments through 2050 (i.e., a 25-year planning horizon) and annually from 2026 through 2030. Water demand projections in this plan are based on population growth within the City’s water service area and incorporate new development projects described in the City’s General Plan and 2025 Water System 30-Year Capital Improvement Master Plan . The projections also account for water use efficiency improvements driven by behavioral trends and increasingly stringent regulations.

4.2.3.1 25-Year Planning Horizon
Table 4-3 reports the City’s projected potable water demands through the year 2050. For the residential sector, p rojected use starts from the post -drought 2025 baseline , accounts for population growth of 17,900 by 2050, and assumes the City’s overall per capita water use declines from a baseline 125 gallons per capita per day (GPCD) to 120 GPCD by 2040 due to water use efficiency trends and Making Conservation a California Way of Life (SB 606/AB 1668) targets. The combined projections for commercial, industrial, and institutional/governmental (City facilities) are similar to the 2020 UWMP, while Landscape and Agricultural Irrigation are significantly lower due to post-drought trends, an evolving Water Efficient Landscape Ordinance (WELO), SB 606/AB 1668 targets, non-functional turf irrigation bans (AB 1572), and NapaSan recycled water conversions. Sales/Transfers/Exchanges to Other Suppliers increases to 800 AF based on the City of St. Helena’s interest in a renegotiated supply agreement. Distribution System Water Loss projections assume the City meets its State Water Board Water Loss Standard and gradually improves due to main replacement projects in the 2025 Water System 30-Year Capital Improvement Master Plan.

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Table 4-3. Total Uses for Potable and Non-Potable Water – Projected (DWR Table 4-2 Retail)

Use Type
Drop down list
May select each use multiple times
These are the only Use Types that will be recognized by the WUEdata online submittal tool
Potable or Non-Potable
(OPTIONAL)
Drop down list
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 opt (AF)
Single Family Potable 5,800 6,000 6,000 6,200 6,450
Multi-Family Potable 2,150 2,250 2,250 2,300 2,400
Commercial Commercial, non-City
Institutional Potable 3,050 3,225 3,300 3,500 3,500
Industrial Potable 150 175 200 200 200
Institutional/Governmental
City of Napa municipal only,
excluding dedicated irrigation
accounts
Potable 30 30 30 30 30
Landscape
Commercial, Industrial,
Institutional Dedicated Irrigation
Meters (DIMs)
Potable 400 400 400 400 400
Agricultural Potable 150 175 200 200 200
Sales/Transfers/Exchanges to other Suppliers
City of St. Helena, Town of
Yountville, California Veterans
Home
Potable 800 800 800 800 800
Other (optional) Hydrant flushing, firefighting,
street cleaning Potable 30 30 30 30 30
Distribution System Water Loss Real and Apparent Losses Potable 1,000 950 900 850 800 13,560 14,035 14,110 14,510 14,810
0 0 0 0 0
13,560 14,035 14,110 14,510 14,810
Add additional rows as needed.

Projected Water Use
(Report To the Extent that Records are Available)
Additional Description
(as needed)
NOTES: The City is a drinking water provider only and does not distribute non-potable water to customers.

Total
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. This table identifies the unit of measure selected in Submittal Table 2-3.

Subtotal Non-Potable
Subtotal Potable
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4.2.3.2 Characteristic Five-Year Water Use
CWC §10635(b) requires urban suppliers to include a five -year Drought Risk Assessment (DRA) in their UWMPs. A key component of the DRA is estimating demands for the next five years (2026–2030) without drought conditions ( i.e., unconstrained demand). Chapter 7 details the DRA, but the five -year demand projections are summarized in Table 4-4. These projections were developed by linearly interpolating between actual 2025 demands presented in Table 4-2 and 2030 demand projections presented in Table 4-3.

Table 4-4. Projected Potable Water Demands for Drought Risk Assessment, AFY(a) 2026 2027 2028 2029 2030
12,481 12,751 13,020 13,290 13,560
(a) Demand projections for 2026–2029 are based on linear interpolation of actual 2025 demands presented in Table 4-2 and the 2030 demand projection presented in Table 4-3.

4.3 DISTRIBUTION SYSTEM WATER LOSSES
System losses are the difference between the actual volume of water delivered into the distribution system and the actual metered consumption. Such apparent and real losses are always present in a water system due to pipe leaks, unauthorized use, faulty me ters, unmetered services (e.g., fire protection and street cleaning), and system flushing.

The City uses the American Water Works Association (AWWA) Water Audits and Loss Control Programs method to annually evaluate its distribution system losses. Regulations require retail water suppliers to include potable distribution system water losses for the preceding five years in their UWMPs (to the extent records are available). Table 4-5 summarizes the City’s status in submitting its AWWA water audits for the previous five calendar years (2020 through 2024). Copies of the City’s Water Loss Audit worksheets for the last five years are provided in Appendix F.1

1 Water Loss Audit Reports are also available online at https://wuedata.water.ca.gov/awwa_plans.

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Table 4-5. Last Five Years of Water Loss Audit Reporting (DWR Table 4-5 Retail)

In November 2022, DWR and the State Water Board adopted water loss standards for urban retail water suppliers. The new regulation provides suppliers with volumetric standards that establish cost -effective levels of achievable water loss based on each supplier’s water system characteristics and budgets.

Beginning in January 2028, suppliers must meet their individual volumetric real loss standards based on a three-year compliance period of the Years 2025, 2026, and 2027. Individual apparent water loss standards must also be met at the same 2028 compliance date. Table 4-6 summarizes the real and apparent water losses for 2024 compared to the City’s 2028 water loss standard. The City anticipates reductions in apparent water loss with an accelerated meter replacement program in the coming years.

The City’s programs to assess and manage water loss are discussed further in Chapter 9.

Public Water System ID #Reported
in Table 2-1 R Reporting Period Submitted to DWR Water
Loss Audit Program (yes/no)
2020 Yes
2021 Yes
2022 Yes
2023 Yes
2024 Yes
CA2810003
DWR NOTES: Suppliers will provide a link to the WUEdata submittals of their Water Loss Audit Reports.

Report submittal status for all five years for each Public Water System as available.

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Table 4-6. Progress Towards 2028 Water Loss Standard (DWR Table 4-6 Retail)

2028 Real Water Loss
Standard per Unit per
day
Units for Real
Water Loss
Drop down list
Number of Units
(Connections or Miles
corresponding with
units selected)
Volume of Total Real
Loss
(from AWWA Water
Loss Audit)
(AF)
2028 Apparent Water
Loss Standard per
Unit per Day
Units for
Apparent Water
Loss
Number of
Connections
Volume of Total
Apparent Loss
(from AWWA Water
Loss Audit)
(AF)
CA2810003 Yes 26.8
Gallons per
Service
Connection per
Day (GPSCD)
26362 660 22.4 6.3
Gallons per
Service
Connection per
Day (GPSCD)
26362 353 12.0
Apparent Water Loss
Did the Water Board Calculate a
Water Loss Standard for this
Public Water System? (y/n)
If no, Supplier will not complete
this row.

Real Water Loss
Public Water
System ID #
Reported in
Submittal
Table 2-1 R
Add additional rows as needed.

Most Recent AWWA Water Loss Audit
Real Water
Loss Per Unit
per Day
Most Recent AWWA Water Loss Audit
Apparent Water
Loss Per Unit per
Day
State Water Board Standard State Water Board Standard
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4.4 ESTIMATING FUTURE WATER SAVINGS
Water savings from codes, standards, ordinances, or transportation and land use plans can decrease the water use for new and future customers . The City will benefit from some “passive savings” associated with an enhanced building code, the State Model Water Efficient Landscape Ordinance (MWELO), and expanded use of recycled water (detailed in Chapter 6 of this plan). The enhanced building code and MWELO are described further below.

To ensure that new construction is extremely water-efficient, the City has adopted local High-Performance Building Regulations that are more stringent than the California Green Building Standards Code (CALGreen).

In Napa Municipal Code (NMC) Chapter 15.04, the City makes several of CALGreen’s voluntary provisions mandatory, including lower residential kitchen faucet flow rates and Energy Star appliance requirements.

For non -residential projects, the City requires an additional 12 percent indoor savings, tighter specifications for clothes washers, dishwashers, ice makers, food steamers, and water sof teners, and lower maximum water pressure. To minimize outdoor water use for new development, the City will continue to enforce the MWELO as it evolves.

Table 4-7 indicates that some passive water savings are included in the City’s projected future water demands. Lower income residential demands are also included in water use projections, as shown in Table 4-7 and detailed in Section 4.5.

Table 4-7. Inclusion in Water Use Projections
(DWR Table 4-3 Retail)

4.5 WATER USE FOR LOWER INCOME HOUSEHOLDS
SB 1087 (2006) requires that water providers develop written policies prioritizing development that includes affordable housing to low income households (Government Code Section 65589.7). In 1999, the City of Napa adopted an Inclusionary Housing Ordinance ( NMC Section 15.94), essentially requiring that 10 percent of all new dwelling units in a residential development project shall be Affordable Units. In 2012, this was converted to an affordable housing impact fee assessed for both residential and commercial developments. The City places these fees in an Affordable Housing Trust Fund which is used to further the goal of providing affordable housing by leveraging other local, State, and Federal funds. Residential development projects may also satisfy the affordable housing impact fee requirements by proposing and Are Future Water Savings Included in Projections?
Drop down list (y/n) Yes
If "Yes" to above, state the section or page number, in the cell to the right, where citations of the codes, ordinances, or otherwise are utilized in demand projections are found.

Optional Suppliers may complete Optional Submittal Table 4-4 R to quantify the expected savings.

Section 4.4
Are Lower Income Residential Demands Included In Projections? Drop down list (y/n) Yes
Optional If the method for accounting Lower Income Residential Demands has been included, provide page number where this accounting can be found. Section 4.5 ATTACHMENT 3

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May 2026

obtaining City approval for an alternate plan, which may include construction or dedication of new affordable housing units.

The projected water demands shown previously in Table 4-3 include water use for single family and multi-family residential housing needed for low -income households, as identified in the City’s 2023-2031 Housing Element (Housing Element).2 A lower income household is defined as a household that has an income below 80 percent of the area median income, adjusted for family size. According to the City’s Housing Element, approximately 38 percent of the City’s households had incomes below 80 percent of the area median income.

Therefore, it is estimated that approximately 38 percent of the City’s residential water demands are attributed to low-income households. Table 4-8 presents the projected water demands for low income single-family and multi-family residential households.

Table 4-8. Projected Water Demands for Lower Income Households Water Use Sector
Water Demands for Low Income Households(a), AFY
2030 2035 2040 2045 2050
Single Family Residential 2,221 2,298 2,298 2,375 2,470 Multi-Family Residential 823 862 862 881 919
Total 3,044 3,160 3,160 3,256 3,389
(a) Based on data from the City’s Housing Element indicating that 38.3 percent of households in the City’s water service area are classified as low income.

4.6 CLIMATE CHANGE CONSIDERATIONS
The City’s future water demand and use patterns may be impacted by climate change. Warmer temperatures are expected to increase landscaping and irrigation demand and lengthen the growing season. In addition, climate change may increase the frequency and in tensity of wildfires, which would increase the fire industry’s water demands.

The potential impacts of climate change on the City’s water supplies are described in Chapter 6, largely based on DWR analyses contained in their Draft 2025 SWP Delivery Capability Report.

2 City of Napa. November 2023. 2023-2031 Housing Element. Accessed at https://www.cityofnapa.org/262/Housing-Element on May 4, 2026.

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
5-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 5
SB X7-7 Baselines, 2020 Target, and 2025 Reporting
In November 2009, SB X7-7 was signed into law as part of a comprehensive water legislation package that addressed both urban and agricultural water conservation. The legislation set a goal of achieving a 20 percent statewide reduction in urban per capita water use by December 31, 2020 (i.e., “20 by 2020”).

To meet the urban water use target requirement, each retail supplier was required to determine its baseline water use, as well as its target water use for the year 2020. Water use is measured in gallons per capita per day (GPCD).

This chapter provides a review of the calculation of the City’s 2020 Urban Water Use Target (2020 Target) and demonstrates that the City has achieved its 2020 Target in 2025 . Although the City missed its 2020 Target in 2020 by approximately four percent, it has since reduced its water use and achieved its 2020 Target. Compliance with the urban water use target requirement is presented in the SB X7-7 Compliance Form, which is included as Appendix G in this plan.

In this UWMP, the City is required to report its compliance with the 2020 Target as of 2020. However, the 2020 urban water use target has since been superseded by the establishment of Urban Water Use Objectives as part of the Making Conservation a California Way of Life regulation adopted on July 3, 2024.

Starting in 2024, the City’s Urban Water Use Objective is calculated and reported annually through a separate process. Additional information on the City’s wate r conservation practices and objectives is included in Chapter 9.

5.1 OVERVIEW AND BACKGROUND
The City’s compliance with SB X7-7 was first addressed in the City’s 2010 UWMP , in which t he City determined its baseline per capita water use and established and adopted its urban water use targets for 2015 and 2020. Actual water use data was divided by the service area population to obtain baseline and target GPCD water use.

SB X7-7 required each urban water retailer to determine its baseline daily per capita water use over a 10-year or 15-year baseline period. In the City’s 2015 UWMP, the 10-year baseline period that the City selected was verified to be 1995 through 2004, and the population and water use targets were updated to reflect 2010 Census data. The City calculated its baselines and water use targets on an individual reporting basis in accordance with SB X7-7 legislation requirements and DWR Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use (2016) (DWR ’s Methodologies).

Details of the specific methodology used to calculate the City’s 2020 water use target are documented in its 2015 UWMP.

The City demonstrated that it successfully achieved its 2015 interim target and confirmed its 2020 Target in its 2015 UWMP. In its 2020 UWMP, the City reported that it did not achieve its 2020 Target. In this chapter, the City demonstrates its progress towards compliance with its 2020 Target.

5.2 2020 DAILY PER CAPITA WATER USE COMPLIANCE
In its 2020 UWMP, the City calculated its actual 2020 water use in accordance with DWR’s Methodologies.

As shown in Table 5-1, urban per capita water use in 2020 was 137 GPCD, which was above the confirmed 2020 Target of 132 GPCD. Therefore, the City did not meet its 2020 final water use target. In 2019, the City was on track to meet its 2020 Target, but COVID-19 pandemic-related increases in residential demand and a historically dry year in 2020 increased per capita water use above the 2020 Target.

ATTACHMENT 3

Chapter 5
SB X7-7 Baselines, 2020 Target, and 2025 Reporting

N-C-424-60-26-28-WP-R-25-UWMP
5-2 City of Napa
2025 Urban Water Management Plan
May 2026

Because the City did not achieve its 2020 water use target, its 2025 urban per capita water use was calculated to determine compliance. As shown in Table 5-1, the City’s urban per capita water use in 2025 was 119 GPCD, which was below the confirmed 2020 water use target of 132 GPCD. Therefore, the City has met its 2020 final water use target.

Table 5-1. SB X7-7 2020 Target Progress (DWR Table 5-1 Retail)

Details of determining the 2025 service area population and gross water use are provided in Sections 5.3 and 5.4, respectively. The City’s 2025 compliance water use is provided in Section 5.5.

5.3 SERVICE AREA POPULATION
To calculate its compliance year GPCD, the City must determine the population that it served in 2025.

Table 5-2 shows the methods used to estimate the City’s 2025 service area population. The City used the DOF data to estimate the 2025 population within City limits. DOF population estimates are based on U.S.

Census data, c hanges in the housing stock, estimated occupancy of housing units, and the number of persons per household. Outside City limits, the City estimated population using the number of dwelling units served and the DOF persons per household data for the unincorporated County. It should be noted that the resident population of Napa State Hospital is served by the City and is also added in separately to the City’s service area population as allowed by DWR ’s Methodologies. The Napa State Hospital population is assumed constant at 1,175 across all years, based on previous reporting from the Executive Director’s office at the Napa State Hospital. The City’s estimated 2025 water service area population is shown in Table 5-3.

Actual 2025 GPCD
(From SB X7-7
Compliance Form)
Did Supplier meet
the 2020 Target in
2025?
No Individual Target 132 137 No 119 Yes
Did Supplier
Achieve Targeted
Reduction for
2020?
Actual 2020 GPCD2020 Target
Regional Alliance
Target or
Individual
Target?
Drop down list
DWR NOTES:

Suppliers calculating a 2025 GPCD will need to complete and submit SB X 7-7 Compliance Tables to verify the use of SB X7-7 Methodologies.

Suppliers that were part of a merger or consolidation since 2020 see Chapter 5 and Appendix P for guidance.

NA=Not Applicable
Check the box if the Supplier was not an Urban Water Supplier during or before the 2020 UWMP reporting cycle. Proceed to the next table.

Only for suppliers that did not meet the
Target in 2020
See DWR NOTES below.

Was Supplier part of a
merger or
consolidation since
2020?
ATTACHMENT 3

Chapter 5
SB X7-7 Baselines, 2020 Target, and 2025 Reporting

N-C-424-60-26-28-WP-R-25-UWMP
5-3 City of Napa
2025 Urban Water Management Plan
May 2026

Table 5-2. Method for 2025 Population Estimate
(SB X7-7 Table 2)

Table 5-3. 2025 Service Area Population
(SB X7-7 Table 3)

5.4 GROSS WATER USE
Annual gross water use, as defined in CWC §10608.12(h), is the water that enters the City’s distribution system over a 12 -month period (calendar year) with certain exclusions. This section discusses the City’s annual gross water use in 2025, in accordance with DWR’s Methodologies.

The City’s gross water use equals the metered production at the Hennessey, Milliken, and Barwick Jamieson WTPs, less deliveries to other agencies (American Canyon, Yountville, St. Helena, Calistoga, and the Veterans Home of California) and agricultural customers. In 2025, the City’s actual gross water use was 11,403 AF as shown in Table 5-4.

Method Used to Determine 2025 Population
(may check more than one)

1. Department of Finance (DOF) or
American Community Survey (ACS)

3. Other
DWR recommends pre-review

2. Persons-per-Connection Method

3. DWR Population Tool
85,366 2025
2025 Compliance Year Population
ATTACHMENT 3

Chapter 5
SB X7-7 Baselines, 2020 Target, and 2025 Reporting

N-C-424-60-26-28-WP-R-25-UWMP
5-4 City of Napa
2025 Urban Water Management Plan
May 2026

Table 5-4. 2025 Gross Water Use
(SB X7-7 Table 4)

5.5 2025 COMPLIANCE DAILY PER CAPITA WATER USE
Sections 5.3 and 5.4 present the City’s 2025 population and gross water use, respectively. The City calculated its actual daily per capita water use for the 2025 calendar year in accordance with DWR’s Methodologies. As shown in Table 5-5, urban per capita water use in 2025 was 119 GPCD, which is below the 2020 Target of 132 GPCD. Therefore, the City has met its 2020 final water use target.

Table 5-5. 2025 Gallons Per Capita Per Day
(SB X7-7 Table 5)

Compared to baseline years, water use in the City’s service area has generally been reduced due to continued water conservation efforts by the City and its customers as shown by the per capita water use of 119 GPCD in 2025. The complete set of SB X7-7 compliance tables is included in Appendix G.

DWR’s Methodologies and CWC §10608.24 allow agencies to adjust their gross water use in 2025 for unusual weather, land use changes, or extraordinary institutional water use. The City has elected not to make the adjustments allowed because these exceptions are not needed to demonstrate compliance with SB X7-7 for 2025.

5.6 REGIONAL ALLIANCE
The City has chosen to comply with the requirements of SB X7-7 on an individual basis. The City has elected not to participate in a regional alliance.

Exported
Water
Change in
Dist.

System
Storage
(+/-)
Indirect
Recycled
Water
This column
will remain
blank until SB
X7-7 Table 4-B
is completed.

Water
Delivered
for
Agricultural
Use
Process
Water
This column
will remain
blank until SB
X7-7 Table 4-D
is completed.
12,211 731 - 77 - 11,403 NOTES: Volumes are in AF. In 2025, the City exported water to the City of St. Helena, the Town of Yountville, and the California Veterans Home.
2025 Volume
Into
Distribution
System
This column
will remain
blank until SB
X7-7 Table 4-A is
completed.
2025 Gross
Water Use
2025 Deductions
Compliance
Year 2025
2025 Gross Water
Fm SB X7-7 Table 4
2025 Population
Fm SB X7-7 Table 3 2025 GPCD
11,403 85,366 119 ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
6-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 6
Normal-Year Water Supply Characterization
This chapter describes and reviews the sources of water that may be available to the City. Projected future water supplies, including the use of recycled water, and the potential use of stormwater, desalinated water, and exchanges or transfers are also described in this chapter. The origin of the City’s water supply and its quantity, as well as the anticipated actions to meet future demands for each water source are discussed.

6.1 OVERVIEW
The City’s existing water supply sources include SWP imports (delivered through the NBA) and local surface water from Milliken Reservoir and Lake Hennessey. The NCFCWCD administers the contract directly with DWR for SWP supplies, and the City receives its annual SWP entitlement through this contract as a SWP subcontractor. Milliken Reservoir and Lake Hennessey are two local surface water reservoirs along tributaries upstream of the Napa River.

All SWP water is delivered to the Edward I. Barwick Jamieson Canyon (Barwick Jamieson) WTP, which was constructed in 1968 and upgraded in 1988 and 2011 . Milliken WTP was constructed in 1976 and treats water diverted from Milliken Creek that was released from Milliken Reservoir. Hennessey WTP began operation in 1981 and treats water from Lake Hennessey.

The following sections discuss the management and anticipated availability of the City’s water supplies under normal water years. The availability of the City’s water supplies under dry conditions, including a single dry year and a drought lasting five years, is described in Chapter 7 of this plan.

6.2 IMPORTED WATER: STATE WATER PROJECT
In 1966, 20 years after the addition of Lake Hennessey and more than 40 years after the creation of Milliken Reservoir, the City added a third source of supply by subcontracting with NCFCWCD for imported surface water from the SWP. The NCFCWCD acts as the SWP contract administrator on behalf of municipalities in the County that own the water entitlements. The SWP diverts water from the Delta at the Barker Slough Pumping Plant east of Vacaville and conveys it approximately 21 miles via the NBA to Cordelia Forebay to serve contractors in Napa and Solano counties. From there, SWP water is pumped an additional 6 miles to the NBA Terminal Reservoirs (two 5 MG raw water storage tanks installed by DWR in 2008 to replace the original 7 MG tank built in 1968). Most of this water represents SWP entitlements for the City and Calistoga, both of which are treated at the Barwick Jamieson WTP. The remainder is American Canyon’s SWP entitlement, which is either conveyed to the adjacent American Canyon WTP or delivered as raw water to American Canyon irrigation customers.

The original 1966 agreement with NCFCWCD provided the City with gradually increasing annual allotments of SWP water, known as “Table A” entitlements, reaching a maximum of 12,500 AFY by 1990.

The agreement was modified in 1982 following DWR efforts to encourage water conservation. The modified agreement reduced the City’s short -term Table A entitlement but increased its final overall entitlement to 18,800 AFY by 2021. In 2009, the SWP contract was amended to accelerate the entitlement schedule, with the Cit y granted its full entitlement of 18,800 AFY beginning in 2010 . The current SWP contract is due to expire in 2035, with an extension to 2085 anticipated.

ATTACHMENT 3

Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-2 City of Napa
2025 Urban Water Management Plan
May 2026

In 2000, the City obtained an additional 1,000 AFY of SWP water in a transfer agreement between NCFCWCD and the Kern County Water Agency (KCWA). Negotiated on behalf of five cities in the County, the agreement established terms for the permanent purchase of 4,025 AFY of SWP entitlement from KCWA. The City and St. Helena purchased the largest shares of this total (1,000 AFY each), while the remaining agencies purchased lesser shares (ranging from 500 to 925 AFY). In 2006, the City purchased St. Helena’s 1,000 AFY KCWA entitlement. Amended several times since 2006, this SWP entitlement transfer agreement currently requires that St. Helena purchase a minimum of 600 AFY from the City, with an option to request an additional 200 AFY.

In 2009, the City signed a water transfer agreement with Yountville to obtain Yountville’s total SWP Table A entitlement of 1,100 AFY and its NBA conveyance capacity. This agreement allows the City to sell up to 25 AFY to Yountville at retail rates for non-drought emergency and fire flow needs only. There is no minimum sales requirement as there is for the St. Helena agreement. These more recent SWP Table A purchases from other County agencies help bolster supplies for City customers during droughts.

The City’s Table A entitlements are summarized as follows:
• NCFCWCD Agreement: 18,800 AFY
• KCWA Purchase (2000): 1,000 AFY
• St. Helena Purchase (2006): 1,000 AFY
• Yountville Purchase (2009): 1,100 AFY
Together, these entitlements total 21,900 AFY and represent the absolute maximum annual yields of Table A water available to the City . Actual deliveries are determined annually by DWR depending on hydrologic conditions. A full (i.e., 100 percent) Table A entitlement (21,900 AF Y) would typically be available only during very wet years . In the Draft State Water Project Delivery Capability Report 20 251 (2025 Draft DCR), DWR estimates that 54 percent of the SWP contractor’s entitlements would be available for delivery in a normal (average) year under existing conditions, and then be reduced to 48 percent in the future (2043) based on DWR’s 50% Level-of-Concern (LOC) Scenario (discussed further in Chapter 7).

For the City, this equates to a normal year Table A delivery of 11,826 AFY through 2040 and 10,512 AFY for 2045 and 2050.

The State Water Board is currently in the process of updating the Water Quality Control Plan for the San Francisco Bay/Sacramento-San Joaquin Delta Watershed (Bay-Delta Plan). Model simulations in initial drafts indicate that the Unimpaired Flow regulatory approach yields significant reductions in SWP Table A allocations for Napa County cities, particularly in critically dry years. The State Water Board continues to refine the model and define impacts. The cities and NCFCWCD, along with the State Water Contractors, support the alternative Healthy Rivers and Landscapes (HRL) approach, which embraces balancing water supply, environmental flows, agriculture, and recreation. Because this HRL approach is expected to be adopted in the final Bay -Delta Plan in 2026, this plan does not include Unimpaired Flow -related Table A curtailments in Chapters 6 or 7. Should this scenario change, future UWMP updates will account for estimated Bay-Delta Plan impacts.

1 DWR, 2025. The State Water Project Draft Delivery Capability Report 2025. State Water Project Draft Delivery Capability Report 2025.

ATTACHMENT 3

Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-3 City of Napa
2025 Urban Water Management Plan
May 2026

There are other types of SWP water (besides Table A entitlements) available to the City, including carryover, North of Delta (NOD) Allocation, Advanced Table A, Article 21, and Dry Year water. These categories are described in the following sections. However, because the following supplies from the SWP are either highly variable or not considered additional supply, they are not included as additional supply in the City’s supply projections for normal years.

6.2.1 Carryover Water
Carryover water is surplus water from a previous year’s entitlement that was stored for use in subsequent years. Stored in San Luis Reservoir, carryover water is considered the first water to be lost if San Luis Reservoir spills. The City typically uses carryover water in the first few months of the year after Article 21 is not available and will continue to do so. Over the long term, this is not considered new supply but simply taking better advantage of existing SWP entitlements.

6.2.2 North of Delta Allocation
Following a 2013 legal settlement resolving Solano County Water Agency et. al. v. Department of Water Resources (“Area of Origin” settlement), the City’s a ctual Table A deliveries have been bolstered by the NOD Allocation. Each year, DWR calculates a separate SWP Table A allocation for NOD contractors in Solano, Napa, and Butte counties and Yuba City. The NOD Allocation is expected to be 5 to 25 percent higher than the standard Table A allocation each year, depending on hydrologic conditions and regulatory and operational constraints applicable to only North of Delta. It will not be impacted by restrictions that affect South of Delta (SOD) exports. Starting in 2015, the NOD Allocation ranged from 5 percent to 15 percent higher than standard Table A in its first seven years of implementation. In 2024 and 2025, the allocations were 2 5 percent and 2 0 percent higher, respectively, than the base SOD allocations of 40 percent and 50 percent. Current litigation with DWR regarding the treatment of this annual NOD incremental entitlement is expected to be resolved in 2026, clarifying when and how the City can access this additional Table A water.

6.2.3 Advanced Table A Program
Another outcome from the Area of Origin settlement, the Advanced Table A Program, consists of additional SWP water that becomes available from a credit account once all available Table A supplies are exhausted, including any carried over from previous years . This credit account can provide the City with an additional 3,772 AFY when the standard (SOD) allocation is less than or equal to 20 percent. When the standard allocation is greater than 20 percent, the City may borrow up to 5,659 AFY. An additional amount may be requested if Solano County Water Agency and Yuba City do not use their maximum Advanced Table A Program entitlements. The cumulative balance in the Advanced Table A Program account must not exceed 21,900 AF, and it resets to zero whenever Lake Oroville spills.

6.2.4 Article 21 Water
Article 21 water is an interruptible surplus SWP supply. Article 21 of the SWP contract allows for the purchase of surplus water beyond Table A entitlements, provided that the contractor can take delivery during the wet season when excess water is available in the Delta without affecting Table A deliveries to other contractors. The City directs NCFCWCD to use an annual delivery schedule that maximizes the City’s use of Article 21 water prior to consumption of carryover water.

ATTACHMENT 3

Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-4 City of Napa
2025 Urban Water Management Plan
May 2026

6.2.5 Dry Year Water
In dry years, DWR decides whether to operate a Dry Year Water Purchase Program based on Article 56 of the SWP contract. Also pursuant to Article 56 , a “Turn-Back Pool” may be established with water from agencies not using their full Table A entitlement, which can be distributed to other agencies requesting additional supplies. NCFCWCD has purchased water through the program and will continue to do so, but it is not considered a reliable supply source due to its variability. In 2008 and 2021, with local reservoir levels low and an initial SWP allocation of just 25 percent and 5 percent, respectively, the City participated in the Yuba Accord Dry Year Water Purcha se Program to supplement available supplies and reduce the need for mandatory drought restrictions for its customers.

6.3 LOCAL SURFACE WATER
This section discusses the City’s two local surface water supply sources: Milliken Reservoir and Lake Hennessey.

6.3.1 Milliken Reservoir
The City began offering water service in 1923 after purchasing the privately -owned Municipal Water Works. This purchase led to the near -term construction of Milliken Dam to address water quality challenges with water diverted directly from the Napa River north of Trancas Street above the salinity gradient and groundwater pumping along Pine Street that effectively pulled water from the Napa River below the salinity gradient. This major project allowed storage of high-quality water from Milliken Creek, a tributary of the Napa River. The resulting Milliken Reservoir located approximately 5 miles northeast of the City , served as the City’s sole water supply source until 1946, when Conn Dam was constructed (creating Lake Hennessey). Milliken Reservoir has historically served as only a seasonal source of supply used in the high-demand summer period when turbidity levels in the reservoir can be effectively treated at the Milliken WTP.

Raw water is currently not taken directly from Milliken Reservoir but is instead released into Milliken Creek by a manually-operated valve system located at the base of the Milliken Dam. About two miles downstream, a diversion dam directs water into a 16 -inch diameter above ground raw water pipeline, which runs approximately 1.75 miles and flows via gravity to the Milliken WTP.

The City’s water rights to Milliken Reservoir, which is fed by an approximately 6,000-acre watershed, are secured through a license with the State Water Board that authorizes the City to divert and store up to 2,350 AFY from Milliken Creek for beneficial use. Milliken Reservoir has an approximate storage capacity of 1,390 AF, much smaller than its average annual inflow of 3,656 AF Y.2 The storage capacity of Milliken Reservoir is limited to 1,390 AF due to seismic stability concerns from the State Division of Safety of Dams that necessitated lowering the reservoir storage elevation. Similar to the 2020 UWMP, this plan assumes an average yield for Milliken Reservoir of 700 AFY through 2040, reduced by 11 percent to 623 AFY in 2045 and 2050 to match the future climate change adjustment for the SWP.3

2 Source: 2050 Napa Valley Water Resources Study.
3 SWP reduction from 11,826 AFY to 10,512 AFY for 2045 and 2050 equates to an 11 percent adjustment.

ATTACHMENT 3

Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-5 City of Napa
2025 Urban Water Management Plan
May 2026

The City holds a permit for direct diversion of 7.74 cubic feet per second (cfs) from Milliken Creek for the period of November through March. However, due to limitations at the Milliken WTP, this water is unable to be treated in the winter due to high turbidity levels.

6.3.2 Lake Hennessey
Located approximately 17 miles north of City Hall, Lake Hennessey is the major local water supply source for the City’s water system. By the 1940s, the City grew to support the World War II effort largely focused at nearby Mare Island, and subdivision development was taxing the Milliken Reservoir, which had served as the City’s single water supply source for more than two decades. To provide additional water supplies, the City constructed Conn Dam, allowing storage of water from Conn Creek, an up-valley tributary of the Napa River. The resulting reservoir, Lake Hennessey, was formed in 1946 and became the City’s primary water supply source until the late 1960s, when it was supplemented by SWP entitlements.

The City’s water rights to Lake Hennessey are secured through a permit with the State Water Board. The permit authorizes the City to divert and store up to 30,500 AF Y from Conn Creek for beneficial use.

Lake Hennessey’s tributary watershed area is approximately 35,000 acres, and it has an approximate storage capacity of 31,000 AF. Storage capacity represents the static volume of the reservoir at spillway elevation, assuming no inflow or outflow, and is indicative of the absolute maximum yield in a wet year.

While the average inflow to Lake Hennessey is 19,692 AFY,4 its average yield is estimated to be 17,500 AFY through 2040, reduced by 11 percent to 15,575 AFY in 2045 and 2050 to match the future climate change adjustment for the SWP.

6.4 GROUNDWATER
As confirmed in Table 6-1, the City does not pump groundwater for municipal supply. The 2050 Napa Valley Water Resources Study (2050 Study), a county -wide water supply planning effort completed in 2005, identified several potential groundwater options that the City may consider in the future. Potential groundwater projects include storing excess SWP entitlements in the groundwater basin along the NBA in Solano County and using new or existing wells in the local groundwater basin for dry year or emergency supplies or as non -potable water for schools and parks. While the City may consider these options, groundwater is not considered part of the City’s water supply portfolio for the 2025 UWMP planning period.

Table 6-1. Groundwater Volume Pumped (DWR Table 6-1 Retail)

4 Source: 2050 Napa Valley Water Resources Study.

Groundwater Type
Drop Down List
May use each category
multiple times
Potable or
Non-Potable
(OPTIONAL)
Drop down list
Location or Basin Name 2021 (AF) 2022 (AF) 2023 (AF) 2024 (AF) 2025 (AF) 0 0 0 0 0
Add additional rows as needed
Total
Check the box if the Supplier does not pump groundwater.

Proceed to the next table.

Check the box if all or part of the groundwater described below is desalinated. (OPTIONAL) ATTACHMENT 3

Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-6 City of Napa
2025 Urban Water Management Plan
May 2026

6.5 STORMWATER
The City does not currently use stormwater as a water supply source and does not have any specific plans to use stormwater to increase its water supplies. While some agencies use stormwater for groundwater recharge, this would not significantly increase the City’s water supply since the City does not currently use groundwater as a municipal supply source. Future water supply studies will review all potential water supplies, with a focus on local resources and consideration of long -term policies such as the 2028 California Water Plan currently in development.

6.6 WASTEWATER AND RECYCLED WATER
Recycled water is municipal wastewater that has been treated to a specified quality, allowing it to be used beneficially. This non-potable water supply is typically distributed to large irrigation users such as golf courses, vineyards, parks, and commercial businesses.

The City is a drinking water supplier only and does not produce or distribute recycled water. Within the City’s service area, recycled water treatment and distribution is managed by NapaSan. Wastewater from the City and surrounding unincorporated areas is treated by NapaSan at their Soscol Water Recycling Facility (WRF), and recycled water produced there is sold by NapaSan to irrigation customers located both inside and outside the City’s service area.

6.6.1 Recycled Water Coordination
In 1998, the City and NapaSan entered into an agreement that permits NapaSan to solicit and provide recycled water service within a specified portion of the City’s service area. A copy of the agreement is attached as Appendix H. The agreement originally defined the recycled service area as lands east of the Napa River, south of Imola Avenue, west of Highway 221, and north of American Canyon, along with other specified areas. Generally, this means NapaSan recycled water can be made available to Napa State Hospital, Stanly Ranch, Napa Valley Commons, South Napa Marketplace, and other nearby sites. A 2018 amendment has enabled additional sites such as Tulocay Cemetery to receive recycled water. The agreement includes a “make whole” calculation to ensure that City’s water revenues are not adversely affected by existing customers suddenly converting to recycled water.

The first City customer to switch to NapaSan recycled water for irrigation was the Napa Municipal Golf Course in 2003. As of 202 5, there are 21 recycled water customers in the City ’s service area , saving hundreds of AFY in potable water. The City recognizes the value of recycled water as a locally produced, reliable supply source and continues to work with NapaSan to further expand its use to meet non-potable demands within the City’s service area. When a City customer switches to NapaSan recycled water for their irrigation needs, demands on the City’s water system are reduced, which helps the City meet its conservation goals.

6.6.2 Wastewater Collection, Treatment, and Disposal
NapaSan collects, treats, and disposes of wastewater generated within the City’s service area. The NapaSan wastewater and City drinking water customer populations have nearly complete overlap.

NapaSan’s Soscol WRF is located at the most southern part of the Napa Valley and discharges treated wastewater to the Napa River.

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Chapter 6
Normal-Year Water Supply Characterization

N-C-424-60-26-28-WP-R-25-UWMP
6-7 City of Napa
2025 Urban Water Management Plan
May 2026

6.6.2.1 Wastewater Collected Within Service Area
As shown in Table 6-2, the Soscol WRF received 8,805 AF of wastewater in 2025 from the City’s service area.

Table 6-2. Wastewater Collected Within Service Area in 2025 (DWR Table 6-2 Retail)

6.6.2.2 Wastewater Treatment and Discharge Within Service Area The Soscol WRF is a secondary/tertiary treatment facility that treats a mixture of domestic and industrial wastewater and has a dry weather design capacity of 15.4 MGD. From November through April (wet season), treated wastewater is discharged to the Napa River. From May through October (dry season), wastewater is treated and used as recycled water. In 2025, the Soscol WRF produced about 2,200 AFY of recycled water that me t the Title 22 California Code of Regulations (Title 22) standards for disinfected tertiary water.

Prior to entering the recycling process, preliminary and primary treatment are used to remove solids and organic matter from the wastewater. For secondary treatment, a portion of the flow enters an activated sludge system consisting of two aeration basins, two secondary clarifiers, four return activated sludge pumps, and two waste activated sludge pumps. Large oxidation ponds provide both storage and secondary treatment for the portion of flow that bypasses the activated sludge system. The ponds promote the growth of algae to oxidize the organic matter in the wastewater.

Recycled water is produced from both activated sludge effluent and oxidation pond effluent. Recycled water treatment consists of:
• Secondary Effluent Pump Station: Effluent from the activated sludge system secondary clarifiers and clarified oxidation pond effluent both flow to the secondary effluent pump station where they are lifted to the filters. Three 100-horsepower (hp) pumps, each capable of pumping 10 MGD, are used.

Name of Wastewater
Collection Agency
Wastewater
Volume Metered
or Estimated?

OPTIONAL
Drop Down List
Volume of Wastewater
Collected from UWMP
Service Area 2025 (AF)
Name of Wastewater
Treatment Plant (WWTP) and
Place ID Number
Drop down list
Is WWTP Located
Within UWMP
Area?
Drop Down List
Napa Sanitation District
(NapaSan) Metered 8,805
Napa Sanitation District WWTP
(Soscol Water Recycling
Facility), Place ID 243858
Yes
8,805
Check the box if there is no wastewater collection system.

Proceed to the next table.

NOTES: Plant influent data obtained from NapaSan engineer in May 2026.

Percentage of 2025 service area population served by wastewater collection system (OPTIONAL)
Percentage of 2025 service area served by wastewater collection system (OPTIONAL) Wastewater Collection Recipient of Collected Wastewater Total Wastewater Received from UWMP
Service Area in 2025:

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• Continuous Backwash Filters: Prior to filtration, more polymers are added, and the water passes through three-stage flocculation. This step conditions the remaining solids so they can then be readily removed through filtration. In the filters, water passes through about six feet of sand, removing the remaining algae solids. To keep the filters clean, air is used to continuously lift, agitate, and wash the sand.
• Disinfectant Rapid Mixing: Sodium hypochlorite disinfectant is added to the filtered water to destroy harmful bacteria. Rapid mixing ensures that the chemical is fully and efficiently blended with the filtered water.
• Chlorine Contact Basins: The chlorinated water sits for approximately two hours in chlorine contact basins to ensure maximum bacteria reduction.
• Recycled Water Storage Reservoirs: Tertiary-treated recycled water is stored in reservoirs for a short time prior to distribution.
• Recycled Water Pump Station: The recycled water pump station delivers the water to customers throughout the southern portions of Napa Valley. The pump station uses three 600-hp pumps to distribute the water at pressures of up to 150 pounds per square inch (psi).

Figure 6-1 shows NapaSan’s existing recycled water system pipelines, including the most recently completed extensions to the Los Carneros Water District (LCWD) and Milliken -Sarco-Tulocay (MST) areas.

Table 6-3 presents the volumes of wastewater treated, discharged, and recycled at the Soscol WRF in 2025. Approximately 21 percent (453 AF) of the total tertiary -treated water generated from the City’s service area was recycled within the City’s service area. The remaining 79 percent (1,720 AF) was delivered outside of the City ’s service area to vineyards, ranchlands, golf courses, and commercial sites located primarily south and east of the City.

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Table 6-3. Wastewater Treatment and Discharge Within Service Area in 2025 (DWR Table 6-3 Retail)

Treatment Level
Drop down list
Volume
(AF)
Treatment Level
Drop down list
Volume
(AF)
Treatment Level
Drop down list
Volume
(AF)
Treatment Level
Drop down list
Volume
(AF)
Treatment Level
Drop down list
Volume
(AF)
Name of other
entity
Napa Sanitation District
WWTP (Soscol Water
Recycling Facility), Place
ID 243858
No 2,173 2,173 Tertiary 453 Tertiary 1,720 Napa Sanitation District
WWTP (Soscol Water
Recycling Facility), Place
ID 243858
No 6,632 6,632 Secondary,
Disinfected - 23 6,162
8,805 8,805 453 1,720 6,162 0 0
Water Recycled Outside of
UWMP Service Area
(enter data as applicable)
Effluent Discharge that is
not a Permitted Recycled
Water Use
(enter data as applicable)
Required Discharge for
Instream Flow
(enter data as applicable)
Delivered to Another Entity for Additional
Treatment
(enter data as applicable)
2025 Outcomes of Treated Wastewater
Check the box if no wastewater is treated or disposed of within the UWMP service area.

Proceed to the next table.

Does This Plant
Treat
Wastewater
Generated
Outside the
UWMP Service
Area?
(OPTIONAL)
Drop down list
Wastewater Treatment
Plant Name and Place ID
Number
Drop down list
Total 2025
Volume of
Water
Treated (AF)
NOTES: Total wastewater treated and recycled water breakdown obtained from NapaSan staff in May 2026. Difference between secondary treated and discharged is evaporative loss from oxidation ponds. Table does note that 1,720 AF of recycled water was delivered to customers outside of the City's drinking water service area. As shown, 453 AF was recycled within the City's service area in 2025.

Total
2025 Volume of
Wastewater
Received from
UWMP Service
Area
(As Reported in
Submittal Table
6-2 R) (AF)
Water Recycled Within
UWMP Service Area
(enter data as applicable)
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Source: Napa Sanitation District
Figure 6-1. Napa Sanitation District Recycled Water Pipelines ATTACHMENT 3

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6.6.3 Potential, Current, and Projected Recycled Water Uses As shown in Table 6-3, 453 AF of tertiary recycled water produced at NapaSan’s Soscol WRF was delivered to recycled water customers within the City’s service area by NapaSan in 2025. This volume was purchased by 21 customers that would otherwise use City drinking water to irrigate their landscapes and vineyards.

Along with the Napa Golf Course at Kennedy Park, other prominent recycled water users include Napa Valley Memorial Park Cemetery, Napa Valley College, Meritage Resort, and the Napa Valley Commons business park. Extension of NapaSan’s recycled water system to the MST area brought recycled water to the Napa State Hospital, the City’s largest potable water customer. While there is now a small amount of recycled water used on the hospital grounds for landscape irrigation, the hospital still must complete a major renovation of its irrigation system before it can use recycled water throughout the entire property.

New recycled water customers since 2020 include the early phase of the Napa Pipe redevelopment project and the first phases of the Stanly Ranch Resort.

Current and projected recycled water uses within the City’s service area are shown in Table 6-4 and consist of agricultural, landscape, and golf course irrigation. These uses are consistent with NapaSan’s 20 22 Recycled Water Policy ( NapaSan Board of Directors Resolution No. 22-020, included as Appendix I) and subsequent recycled water system pipeline extensions. Recycled water use within the City is projected to increase to approximately 800 AFY by 2050, with most of the growth occurring in landscape irrigation.

Table 6-5 compares the 2025 projected recycled water use from the City’s 2020 UWMP to the actual 2025 recycled water use. Actual recycled water use in 2025 was below projections from the City’s 2020 UWMP due to overestimated use at Stanly Ranch Vineyards and Resort, and slower than expected conversions of commercial and institutional landscapes in South Napa.

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Table 6-4. Recycled Water Direct Beneficial Uses Within Service Area (DWR Table 6-4 Retail)

Volume Narrative page number
(OPTIONAL)
Agricultural irrigation Non-Potable Vineyard Irrigation 63 100 100 100 100 100 Landscape irrigation (exc golf
courses) Non-Potable Commercial and Institutional
Landscaping 221 300 500 500 500 500
Golf course irrigation Non-Potable Napa Municipal Golf Course at Kennedy Park 169 200 200 200 200 200
0 0 0 0 0 0 0
453 600 800 800 800 800 0
453 600 800 800 800 800 0 0Total
Use Type
Drop down list
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop down list
Additional Information
(as needed)
Add additional rows as needed
NOTES: Because no additional golf courses exist in the City service area and agricultural (vineyard) areas are very limited, those types of recycled water use will remain steady. Commercial/institutional landscaping uses have the potential to expand based on NapaSan and City policy. 2050 (AF)2025 (AF) 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) Subtotal Potable
Subtotal Non-Potable
Check box if recycled water is not used and is not planned for use within the service area of the supplier. The supplier will only complete the column on "Potential Recycled Water Use" and submit an accompanying narrative on the feasibility of that potential recycled water use.

Potential Recycled Water Use
Name(s) of Facility/ies Producing (Treating) the Recycled Water (OPTIONAL) : Napa Sanitation District WWTP (Soscol Water Recycling Facility) Name of Supplier Operating the Recycled Water Distribution System (OPTIONAL) : Napa Sanitation District (NapaSan) Volume of Supplemental Water Added in 2025 (OPTIONAL) :

Source of 2025 Supplemental Water (OPTIONAL) :

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2025 Urban Water Management Plan
May 2026

Table 6-5. 2020 UWMP Recycled Water Use Projection Compared to 2025 Actual (DWR Table 6-5 Retail)

6.6.4 Actions to Encourage and Optimize Future Recycled Water Use As described above, recycled water within the City is supplied by NapaSan. The City will continue to work closely with NapaSan to expand recycled water use throughout the City’s service area. Table 6-6 lists anticipated future recycled water use increases within the City’s service area.

Table 6-6. Methods to Expand Future Recycled Water Use
(DWR Table 6-6 Retail)

6.7 DESALINATED WATER
The City does not currently have a desalination program, nor does it plan to implement one. 2020 Projection for
2025 (AF)
2025 Actual Use
(AF)
100 63
515 221
220 169
835 453
Check the box if recycled water was not used in 2025 nor previously projected for use in 2020.

Proceed to the next table.

Agricultural irrigation
NOTES: 2020 UWMP overestimated vineyard irrigation volumes in the Stanly Ranch area and the pace of commercial/institutional recycled water conversions in South Napa.

Total
Use Type
Drop Down list
Landscape irrigation (exc golf courses)
Golf course irrigation
Name of Action Description
Expected Increase in
Recycled Water Use
(AF)
Vineyards in Stanly Lane area Connect remaining unconnected vineyard acreage in southwest Napa 20
Stanly Ranch Resort
Connect remaining landscape and vineyard areas as
final phases of resort/housing construction are
completed
60 Napa Pipe Complete full connection of all common area landscaping in Napa Pipe project 40
Napa State Hospital Full connection for entire facility landscape 80 South Napa Infill Connect Imola Avenue commercial landscapes 60 Gasser Infill Connect residential and commercial landscapes on former Gasser Foundation lands 60
320
320
NOTES: Table represents scheduled or anticipated actions within City of Napa drinking water service area only.

Check the box if the Supplier does not plan to expand recycled water use in the future. Supplier will not complete the table below but will provide narrative explanation.

Provide page location of narrative in the UWMP
Add additional rows as needed
Unit Conversion to AF
Planned
Implementation Year
2028
2029
2035
2030
2032
2034
Total (AF)
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May 2026

6.8 EXCHANGES AND TRANSFERS
The City has considered and will continue to consider opportunities for water exchanges or transfers with water right holders if opportunities arise with acceptable terms and conditions. These potential opportunities could include, but would not be limited to, one-time transfers from farmers who choose to fallow fields and auction off their water. The 2050 Study recommended that County agencies take advantage of NBA conveyance capacity by importing dry year supplies from outside the County. Known as the “Fill the Pipe” option, this would require negotiation of a long-term transfer agreement for reliable dry year supplies from agencies such as Butte County, the City of Vallejo, and Sacramento River users.

NCFCWCD and the City are investigating the potential for a permanent long -term agreement to receive dry year transfers from a fellow State Water Contractor. Should this materialize, the impacts on dry year supply scenarios in Chapter 7 will be accounted for in a future UWMP update.

With significant extra SWP carryover water available in 2024 and 2025, the City made transfers totaling more than 9,000 AF to agencies in Tulare and Kern Counties, receiving much needed capital funds.

6.9 FUTURE WATER PROJECTS
This section discusses the City’s potential future water supply projects, including WTP improvements and options to increase future water supplies. Since efforts to evaluate these projects are preliminary, their supplies are not quantified nor are they inc luded in Table 6-7. As future water projects are finalized or agreements made, their supply contributions will be quantified in future UWMPs.

Table 6-7. Expected Future Water Supply Projects or Programs (DWR Table 6-7 Retail)

6.9.1 Water Treatment Plant Projects
Improvements to the Barwick Jamieson WTP were completed in 2011, increasing the treatment capacity from 12 MGD to approximately 20 MGD. The ultimate capacity of the Barwick Jamieson WTP is expected to reach 24 MGD, which will help the City treat all of its entitled water supplies from the SWP. While not actually creating new supply, the proposed treatment capacity expansion essentially has the same effect, allowing the City to maximize supplies to which it is entitled. By using more water from the SWP in select years, the City can preserve its local reservoirs for dry years to provide additional reliability.

The Milliken WTP can reliably meet drinking water standards when treating high -quality summer flow releases; however, its existing direct filtration process struggles to treat elevated turbidity and naturally Drop Down
List
(yes/no)
If Yes,
Supplier Name
Planned for Use in
Year Type
Drop Down List
Check the box if some or all of the supplier's future water supply projects or programs are not compatible with this table and are described in a narrative format.

Check the box if there are no expected future water supply projects or programs that provide a quantifiable increase to the agency's water supply.

Proceed to the next table.

Planned
Implementation
Year
Add additional rows as needed
Joint Project with other
suppliers? Expected Increase
in Water Supply
to Supplier
(This may be a
range) (AF)
Provide page location of narrative in the UWMP
Name of Future Projects
or Programs
Additional Description
(as needed)
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
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occurring iron associated with winter flows. In 2024, the City retained Carollo Engineers to evaluate potential upgrades that would allow greater beneficial use of the City’s existing water rights, including License 5208 (2,000 AF diversion to storage from November through March) and Permit 18448 (7.74 cubic feet per second (cfs), or approximately 2,350 AF annually, via direct diversion). Analysis of watershed hydrology and historical reservoir operations shows that Milliken Reservoir fills and spills annua lly, with more than 5,000 AF spilling in an average year and approximately 1,013 AF reliably available for diversion in a dry year after instream flow requirements. Seismic modifications in 2008 reduced reservoir storage capacity from 1,986 AF to 1,390 AF, and the Milliken WTP currently treats about 700 AF per year. Carollo’s study is evaluating the addition of roughing filters to improve winter turbidity and metals removal while avoiding full conventional treatment due to site constraints and operational c onsiderations. Depending on final performance testing, upgrades could increase annual treated supply to an estimated range of 930 to 1,860 AF, with the higher volume achievable if treatment capacity is expanded to 4.2 MGD and winter flows can be treated from January through March in compliance with regulatory standards.

The City is advancing the Lake Hennessey Spillway Flow Expansion Project to safely accommodate flows associated with the probable maximum flood (PMF) and address updated hydrologic criteria following the 2017 Oroville Dam spillway erosion . While the spillway is currently designed for 14,000 cfs, updated National Oceanic and Atmospheric Agency ( NOAA) hydrologic and hydraulic (H&H) analyses indicate potential outflows of approximately 38,900 cfs, which could result in dam overtopping of up to 1.5 feet.

Earlier expansion concepts were evaluated in 1968 and 1988 but were not implemented due to funding constraints. Since 2017, the City has conducted updated studies and completed interim repairs in 2019.

The current project, estimated at approximately $11 million, would expand spillway capacity through alternatives such as widening the channel, modifying slopes, raising the dam, or incorporating a gated structure such as a labyrinth weir. In addition to improving dam safety and extending the life of the 75-year-old facility, certain alternatives could increase reservoir storage by approximately 4,560 to 6,840 AF through a 4- to 6-foot raise in water surface elevation. The City is pursuing state and federal funding assistance, including coordination with the U.S. Army Corps of Engineers and application to the California Water Infrastructure Financing Program, and will evaluate financing options to minimize cost impacts to ratepayers.

6.9.2 Sites Reservoir
The Sites Reservoir Project would be a 1.8 million AF off -stream surface storage reservoir located in the Sacramento Valley approximately 10 miles west of the town of Maxwell in Colusa County. The proposed Sites Reservoir will be filled by diverting excess Sacramento River flows originating from unregulated upstream tributaries. Diversions can potentially occur in any month or water year type but would be greatest in the winter months with an emphasis on capturing flows from storm events. The Sites Reservoir will operate in cooperation with CVP and SWP system facilities to produce a wide range of public and ecosystem benefits that can be flexibly managed to adapt to future changes, depending on need and priority.

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In January 2022, the City submitted a Letter of Interest to the Sites Project Authority to express its interest in participating in the Site Reservoir Project at a level of 4,000 AF of reservoir release capacity. However, based on the current project participation, and the level of interest of additional potential participants, it may not be possible for the City to become a participant. The Sites Project Authority is evaluating the development of a water transfer program that would allow project participants to transfer a portion or all of their share of capacity to other agencies.

Currently, there are no participants willing to reduce their allotments to free up water supply for new participants to buy in. A secondary means of achieving access to Sites Reservoir water supply would be to execute an agreement with the City of American Canyon who is an original participant and requested 4,000 AF in Sites Reservoir. However, the transfer window must be defined to determine the value of securing water supply from Sites Reservoir. There is more value when there is increased flexibility as to when the water can be moved through the existing S WP infrastructure. The transfer window for Sites Reservoir water, if the same as the transfer window applied to the SWP export pumps, will be limited to June through November in most years depending on conditions. As of July 2025, the transfer windows are not fully defined. The City remains on the waiting list for project participants and will continue to monitor the viability of participation, including other Sites Reservoir participants such as Glenn -Colusa Irrigation District, that may be willing to reliably sell water, and a ccess conveyance capacity in SWP infrastructure that would be used to move the water.

6.9.3 Advanced Water Purification Facility
While traditional surface and imported supplies will remain foundational to the region’s water supply portfolio, the City and NapaSan view non-potable and potable reuse as critical components of long-term water supply reliability. To evaluate the feasibility of incorporating purified water through raw water augmentation or treated water augmentation , the agencies commissioned the Napa Purified Water Feasibility Study (Carollo Engineers, March 2024), which evaluated the quantity of recycled water that would be available and the cost to construct and operate the Advanced Water Purification Facility (AWPF) to produce purified water to meet Title 22 drinking water standards for direct potable reuse . The study evaluated the seasonal availability of excess recycled water from the Soscol WRF, primarily during winter and shoulder seasons when recycled water i s not needed for irrigation and analyzed construction and operational costs for an AWPF at capacities of 1.8 MGD, 6 MGD, and 10 MGD at two potential locations:
the NapaSan Solid Waste Recycling Facility and the City’s Barwick Jamieson WTP. The AWPF would utilize advanced treatment processes including ozone and biologically activated carbon, membrane filtration, reverse osmosis, ultraviolet advanced oxidation, disinfection, and engineered storage buffer.

The preferred alternative identified in the study is a 6 MGD AWPF operating approximately six months per year, producing an estimated 2,231 AF of water. Capital costs are estimated at approximately $218 million for treated water augmentation at the NapaSan site (approximately $7,700/AF) and $258 million for raw water augmentation at the Barwick Jamieson WTP (approximately $8,700 /AF), with lower costs at the NapaSan site largely due to reduced pipeline and pumping requirements. The project would require new conveyance pipelines, concentrate disposal facilities, and additional operational staffing. The agencies identified a contracted services governance structure as the most viable implementation approach. Development would occur in phased steps including planning, demonstration and public outreach, implementation, and operations, with an estimated timeline of approximately 11 years.

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6.9.4 Joint Powers Agreement or Other Cooperative Agreement with Other Local Entities
As recommended in the Napa Valley Drought Contingency Plan (Brown and Caldwell, 2022), the City and municipal water providers in Napa Valley have embarked on a valley-wide optimization plan to determine if use of existing water supplies could be optimized in a manner that results in greater reliability and redundancy of drought year supplies. Initial discussions have considered interties and coordinated operations to determine what future infrastructure investments could be avoided by participants if shared investments are constructed instead.

Preliminary hydraulic assessments have determined that investments are needed to address flow restrictions and/or increase pressure to serve portions of St. Helena and Calistoga’s service areas, particularly during peak demand seasons. Several of the munic ipalities in Napa County have small reservoirs that fill and spill each year; these reservoirs provide local, low-cost water throughout the winter months, but storage is insufficient for multi -year droughts. Each entity must define their capital investment needs to understand what alternate investments could be made regionally, rather than individually. For example, if a water treatment facility needs upgrades to meet seasonal winter water quality challenges and an existing alternate source could be substit uted with less capital outlay, greater optimization would result.

Currently, sufficient information regarding system hydraulic restrictions and understanding of individual system pressure criteria were not available to fully define potential synergies across all municipal providers. It is recommended the City and neighboring agencies continue discussions and mutual system considerations to collectively optimize investments.

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6.10 SUMMARY OF EXISTING AND PLANNED SOURCES OF WATER
Table 6-8 shows the actual sources and volumes used to meet City water demands in 202 5. Most of the City’s water supply in 202 5 came from Lake Hennessey, with the remainder coming from the SWP. No water supply from Milliken Reservoir was used in 2025 due to continuing recovery from raw water pipeline damage suffered in the 2017 Atlas Fire.

Table 6-8. Water Supplies – Actual
(DWR Table 6-8 Retail)

Projected supplies that are reasonably available in normal water years through 20 50 are shown in Table 6-9. The City’s water supply sources are projected to have a combined 30,026 AFY available in 2030 through 2040. Climate change impacts are assumed to reduce both SWP and local water supplies by about 11 percent (to 26,710 AFY) beginning in 2045.

Water Supply
Drop down list
May use each category multiple times.

These are the only water supply
categories that will be recognized by the
WUEdata online submittal tool
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
Actual Volume
(AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes' below
(AF)
Supply from Storage Lake Hennessey Potable 8,885 30,500 Supply from Storage Milliken Reservoir Potable 0 2,350
Purchased or Imported Water State Water Project Potable 3,326 21,900 12,211 54,750
0 0
12,211 54,750
2025
NOTES: Total Entitlements represent the annual diversion and storage Water Rights for the two local reservoirs and the City's contractual 100% Table A allocation for the State Water Project.

Add additional rows as needed
Total
Subtotal Potable
Subtotal Non-Potable
Additional Description
(as needed)
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Table 6-9. Water Supplies – Projected
(DWR Table 6-9 Retail)

Water Supply
Reasonably
Available
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Reasonably
Available
Volume (AF)
Total Entitlement
(OPTIONAL)
See 'DWR Notes'
below (AF)
Supply from Storage Lake
Hennessey Potable 17,500 30,500 17,500 30,500 17,500 30,500 15,575 30,500 15,575 30,500 Supply from Storage Milliken
Reservoir Potable 700 2,350 700 2,350 700 2,350 623 2,350 623 2,350 Purchased or Imported Water State Water
Project Potable 11,826 21,900 11,826 21,900 11,826 21,900 10,512 21,900 10,512 21,900 30,026 54,750 30,026 54,750 30,026 54,750 26,710 54,750 26,710 54,750 0 0 0 0 0 0 0 0 0 0
30,026 54,750 30,026 54,750 30,026 54,750 26,710 54,750 26,710 54,750 Projected Water Supply (Report to the Extent Practicable) Drop down list
May use each category multiple
times. These are the only water
supply categories that will be
recognized by the WUEdata online
submittal tool
Additional
Detail on
Water Supply
Potable or Non-Potable
(after treatment if treated)
(OPTIONAL)
Drop Down list
2050 (opt)
Add additional rows as needed
Total
NOTES: Reasonably Available Volumes are based on an average water year. Through 2040, State Water Project supplies are 54% of Table A (with no Carryover, Article 21, or North of Delta allocation assumed). This Table A allocation represents an average year under Existing Conditions (Adjusted Historical Hydrology) as contained in The State Water Project Draft Delivery Capability Report 2025, DWR, December 2025. 2045 and 2050 use a 48% Table A allocation based on the report's 2043 50% Level of Concern under Future Climate Change Conditions. Local reservoirs supplies are reduced 11% in 2045 and 2050 to match the climate change adjustment for the State Water Project. 2030 2035 2040 2045
Subtotal Non-Potable
Subtotal Potable
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6.11 CLIMATE CHANGE IMPACTS
There are concerns that a warming trend that occurred during the latter part of the 20th century will likely continue through the 21st century. Numerous studies have been conducted to evaluate the potential impacts of climate change to water resources. Based on these studies, climate change could impact California’s water resources in the following ways:
• Reductions in the average annual snowpack due to a rise in the snowline and a shallower snowpack at low and medium elevations and a shift in snowmelt runoff to earlier in the year
• Changes in the timing, intensity, and variability of precipitation, and an increased amount of precipitation falling as rain instead of as snow • Long-term changes in watershed vegetation and increased incidence of wildfires that could affect water quality
• Sea level rise and an increase in saltwater intrusion • Increased water temperatures with accompanying potential adverse effects on some fisheries and water quality
• Increased evaporation and irrigation need
• Changes in urban and agricultural water demand
Because the SWP is a major source of the City’s water supply, climate change impacts to the Sacramento–San Joaquin Delta present significant concerns. The Draft 2025 DCR identifies the following potential climate-related impacts to Delta and SWP operations:
• Changes in runoff and snowmelt timing could affect storage reservoir operations by:
— Increasing the need for flood control storage due to larger and more frequent winter runoff events;
— Reducing opportunities to refill reservoirs during late spring and early summer; and — Decreasing the availability of surface water supplies during the summer and fall seasons.
• Delta levee failures, resulting from sea level rise, seismic events, inadequate maintenance, or a combination of factors, could:
— Cause saltwater intrusion that degrades Delta water quality; and — Disrupt SWP conveyance and exports for extended periods, as major levee failures may require months or years to repair.
• More intense storms and higher runoff volumes could adversely affect Delta water quality by increasing sediment loads and transporting higher levels of urban and agricultural contaminants, potentially limiting SWP operations.

These impacts from climate change have been incorporated into the City’s projected water supply from the SWP. The City has also evaluated the impacts of climate change to its local water supplies and has incorporated similar climate change impacts into its local surface water supply projections.

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6.12 ENERGY INTENSITY
In accordance with CWC Section 10631.2(a), the energy intensity to provide water service to the City’s customers over a one -year period is presented in this section to the extent that the information is available. The amount of energy to divert, pump, treat, and distribute the City’s water supply within the system it owns and operates is included. The amount of energy the SWP requires to pump and deliver raw water to the City is excluded.

Water energy intensity is the total amount of energy, calculated on a whole -system basis, used to deliver water to the City’s customers for use. Energy intensity is the total amount of energy in kilowatt-hours (kWh) expended per million gallon (MG) of water taken from the City’s source to its point of delivery. Understanding the whole-system energy intensity would allow the City to develop the following water supply management and system operation strategies:
• Identifying energy saving opportunities, as energy consumption is often a large portion of the cost of delivering water
• Calculating energy savings and greenhouse gas emissions reductions associated with water conservation programs
• Identifying potential opportunities for receiving energy efficiency funding for water conservation programs
• Informing climate change mitigation strategies
• Benchmarking energy use at each water acquisition and delivery step and comparing energy use among similar agencies
As shown in Table 6-10, the total energy intensity for the City’s water service in 2025 was approximately 748 kWh/MG. To provide a more accurate energy intensity calculation, the water volume used includes 799 AF that the City treated and wheeled to American Canyon and Calistoga in 2025.

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Table 6-10. Recommended Energy Reporting - Total Utility Approach (DWR Table O-1B)

Since NapaSan manages all wastewater and recycled water operations (i.e., collection, treatment, discharge, and distribution) within the City’s service area, energy reporting for wastewater and recycled water does not apply to the City.

Water Delivery Product
drop down list
(If delivering more than one type of product recommend using Table O-1C)
Retail Potable
Deliveries
Start Date of Reporting Period 1/1/2025
End Date of Reporting Period 12/31/2025
Is upstream embedded energy in the values reported? No
Units of Measure for Water AF Total Utility
See DWR NOTES Hydropower Net Utility
13,010 - 13,010 3,171,768 - 3,171,768 748 - 748 Quantity of Self-Generated Renewable Energy
75000 kWh
Data Quality (Estimate, Metered Data, Combination of Estimates and Metered Data) Metered Data
Data Quality Narrative:

Narrative:

Energy Intensity (kWh/vol. converted to MG)
Volume of Water Entering Process includes 799 AF that the City treats and wheels to the Cities of American Canyon and Calistoga. This provides a more accurate Energy Intensity in this Total Utility Approach. Metered electricity data were tabulated for all relevant City of Napa Pacific Gas & Electric (PG&E) billings covering calendar year 2025.

Only for Water Delivery Products Under the Urban Water Supplier's Operational Control Sum of All Water Management
Processes Non-Consequential Hydropower
DWR NOTES:

Total Utility: The volume of water entered in the “Total Utility” column should equal the volume of water entering the distribution system (excluding recycled water); in most cases, this is the total volume calculated in UWMP Table 4-1: 2025 Actual Total Uses for Potable and Non-Potable Water. Note if recycled water is included in your Submittal Table 4-1, you must exclude it from your volume in this table.

Electricity is consumed primarily at three water treatment plants and ten pump stations within the City's operational control. Pumping raw water from Lake Hennessey to the Hennessey Water Treatment Plant consumes the largest amount of energy. This is also the site of the City's solar photovoltaic system, which is capable of producing up to 600,000 kWh per year; however, the system was down for most of 2025 due to failed inverters and other needed repairs, and solar production was limited.

Volume of Water Entering Process
Energy Consumed (kWh)
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CHAPTER 7
Water Service Reliability and Drought Risk Assessment
This chapter describes the City’s water service reliability under various hydrologic conditions, including a severe drought for the next five years. The City’s existing and planned water management tools for increasing water supply reliability are also addressed. Responses to actual water shortage conditions are detailed in Chapter 8 of this plan.

7.1 WATER SERVICE RELIABILITY ASSESSMENT
This section presents the constraints on the City’s existing and planned water supply sources and describes the historical basis for projecting available supplies under various hydrologic conditions (i.e., normal year, single dry year, and five consecutive dry years). The City’s water service reliability is then presented in five-year increments through 2050 based on previous analysis of water use (discussed in Chapter 4) and supply (discussed in Chapter 6). Finally, this section discusses the City’s water management tools and options to promote regional supply reliability and minimize the need to import water from other regions.

7.1.1 Constraints on Water Sources
This section discusses the reliability constraints on the City’s water supply sources and the City’s strategies for managing the risks associated with each supply source. The year-to-year reliability of water supplies from Lake Hennessey, Milliken Reservoir, and the SWP depends on various climatic, environmental, legal, and water quality factors. Each of these factors is discussed in the following sections.

7.1.1.1 Climate Variability
Weather patterns affect hydrologic conditions, which help determine annual SWP deliveries. In critically dry years like 2014 and 2021, SWP contractors received as little as 5 percent of their annual entitlement.

Because the City uses SWP supplies, the City is somewhat dependent on precipitation and drought conditions in the Sacramento and San Joaquin river basins. However, with local reservoirs augmenting the City’s supply from the SW P, the City is not as vulnerable to climatic effects on its SWP supply. We ather patterns and annual rainfall in the local Lake Hennessey and Milliken Reservoir watersheds affect their yields.

With the conservative assumption that dry conditions will occur simultaneously in the SWP and local watersheds, the City is confident in the minimum supplies presented in this plan for single dry and multiple-dry year conditions. As discussed in Chapter 6 of this plan, climate change may increase the variability in water supply for the City and is addressed in the City’s supply projections.

7.1.1.2 Environmental/Legal Restrictions
SWP water is conveyed to the City through the NBA from the Delta. With more than 20 million Californians and millions of acres of irrigated farmland relying on the Delta for water, it is the hub of the State’s water distribution system. With runoff from two major river systems flowing into San Francisco Bay, the Delta is also a productive habitat for wildlife, including several endangered species.

The Delta also serves as a critical migration corridor for salmonid species traveling between their natal streams and the Pacific Ocean and provides habitat for the Delta Smelt, a listed species requiring regulatory protection. Protection measures for thes e species, including operational constraints on pumping, can affect Delta water exports. The SWP is currently operated in compliance with applicable biological opinions and related regulatory requirements issued by the U.S. Fish and Wildlife Service and National Marine Fisheries Service, as well as subsequent updates and court decisions. In the Draft 2025 SWP Delivery Capability Report (Draft 2025 DCR), DWR incorporates these regulatory and environmental ATTACHMENT 3

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constraints into its modeling of future SWP supplies. Consistent with a conservative planning approach, the 2025 Draft DCR assumes that existing institutional, environmental, regulatory, and legal constraints remain in place over the planning horizon.

As described in Chapter 6 of this plan, some of these SWP environmental impacts for the City have been mitigated by the “Area of Origin” settlement. DWR now calculates a separate SWP Table A allocation for North of Delta (NOD) contractors that will not be affected by restrictions that reduce South of Delta exports.

Through permits and licenses with the State Water Board, the City has a legal entitlement to use water from its local reservoirs (Lake Hennessey and Milliken Reservoir). These appropriative water rights allow the City to divert and store up to 30,500 AFY from Conn Creek and 2,350 AFY from Milliken Creek for beneficial use. The water rights require the City to allow sufficient releases from the reservoirs to provide minimum stream flows, which have been taken into consideration in estimating water supply availability.

The City continues implementation of aspects of the Master Plan for Reservoir and Watershed Operations, one portion of which relates to modeling runoff within the watershed. As part of this effort, the City has been coordinating with the County, who has jurisdiction over land use in thousands of acres of watershed lands, to implement a monitoring and analysis plan and define tributary water quality with the goal of understanding areas that may contribute to changes in water quality. The program ensures targeted efforts and resolution to ensure water quality protection. Another aspect of the Master Plan for Reservoir and Watershed Operations is an assessment of spillway capacity and a probable maximum storm. The recommended capital improvements could impact, and ideally increase, annual supplies available from the City’s local reservoirs.

7.1.1.3 Water Quality
Because the Delta is an estuary, salinity is a potential water quality concern. SWP water is required to meet salinity and other water quality objectives for the Delta established by the State Water Board, and these objectives may restrict SWP exports from the Delta.

The City consistently meets drinking water standards prescribed by the U.S. Environmental Protection Agency and the State Water Board. SWP source water can provide a challenge for the Barwick Jamieson WTP during winter storms, when turbidity increases. While process changes including ozonation have improved the WTP’s ability to handle high -turbidity raw water, improved watershed management practices near the intake may also help mitigate the issue in the future. The NBA intake at Barker Slough has experienc ed periodic water quality problems, in part because of organic material from decaying vegetation. Habitat restoration projects initiated to mitigate impacts associated with the Bay Delta Conveyance Project (formerly Twin Tunnels) near the Barker Slough Pum ping Plant may further reduce the water supply reliability of the NBA. Potential alternate intake locations for the NBA that would improve raw water quality and avoid Delta Smelt habitat are being evaluated.

Raw water quality is also an issue for the Milliken Reservoir, as higher turbidity levels in the fall, winter, and spring reduce the effectiveness of the Milliken WTP’s direct filtration system. The City is considering modifications to Milliken WTP so that this reservoir can be used as a supply source year-round. The supply reliability data in this plan reflect the current practice of using Milliken supplies only during the summer, when lower turbidity levels can be effectively treated.

The Master Plan for Reservoir and Watershed Operations also reviewed water quality impacts to supply.

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high total organic carbon that increase the formation potential for disinfection byproducts. City staff is cognizant of these challenges and uses vigilance to provide the highest quality water to customers throughout the year with limited exception when constrained due to infrastructure challenges ahead of the treatment plant process . Management of existing reservoir water supplies and alternate supply options to address loss of quantity and quality continues to be an important part of ongoing reservoir and watershed management.

7.1.2 Year Type Characterization
Water supplies can vary year to year depending on hydrologic conditions. Historical data, where available, were used to develop a projected yield for each water supply source under three conditions: (1) normal water year, (2) single dry water year, and (3) five consecutive dry water years. In accordance with the DWR Guidebook, each condition is defined as follows:
• Normal Water Year: The year or averaged range of years in the historical sequence most closely representing average water supply.
• Single Dry Water Year: The year with the lowest water supply in the historical sequence. • Five-Consecutive-Year Drought: The driest five-year historical sequence.

The following sections describe the historical calendar years selected to represent each of the above conditions for local surface water and SWP supplies.

7.1.2.1 Basis of Water Year Data – Local Surface Water
The City’s local surface water supplies are stored in Lake Hennessey and Milliken Reservoir, and each reservoir has a yield that varies with hydrological conditions. During droughts, reduced yields are supplemented by releasing additional stored water (i.e., reservoir drawdown or depletion). Therefore, in single or multiple dry years, local surface water supplies consist of two components: reservoir yield and reservoir depletion. Yield represents the amount of annual recharge, while depletion is the change in reservoir low point from one year to the next. The depletion amount is a factor of water use, evaporation, and bypass flows. Evaporation depends on the climate and the water surface area in the reservoir. The sum of evaporation and bypass losses is assumed to be 1,400 AF Y based on the Lake Hennessey median value for the 2001 to 2020 period.

The driest five -year historical sequence for the City occurred during 1987-1992. The Lake Hennessey storage pattern for that period is shown in Figure 7-1, which also notes the yield and depletion for the 1987-1988 period. The recharge amount of 7,700 AF in the winter of 1987 -1988 represents the yield.

Depletion of 800 AF is the difference between the reservoir low points.

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Figure 7-1. Lake Hennessey Storage During 1987-1992 Drought Estimated reservoir yields for Lake Hennessey and Milliken Reservoir for the different water year conditions are presented in Table 7-1 and are derived from reservoir conditions experienced in the 1987-1992 drought.

For Lake Hennessey, the normal year yield of 17,500 AF was derived from a yield curve based on watershed modeling and fifty years of rainfall data, as noted in the 2050 Study. The Lake Hennessey reliable yield of 4,800 AFY for multiple dry years is based on the average annual recharge in the reservoir from 1987 through 1992. Lake Hennessey’s firm yield of 2,000 AFY (for a single dry year) is the rounded -up value of the lowest recharge amounts encountered in that drought. Milliken Reservoir typically fills and spills each winter, with a reliable yield of 700 AF. In the extreme single dry year case, a firm yield of 400 AFY is assumed for Milliken Reservoir.

Table 7-1. Estimated Local Reservoir Yields
Source
Yield, AFY
Normal Year Single Dry Year Multiple Dry Years
Lake Hennessey 17,500 2,000 4,800
Milliken Reservoir 700 400 700
Total 18,200 2,400 5,500

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For both the single dry year and the multiple dry year case s, Lake Hennessey is assumed to start at 26,000 AF of storage (out of a total storage capacity of 31,000 AF) . The basis for this assumption is that, except for the 1987 -1992 drought years shown in Figure 7-1 and the 2021 dry year , Lake Hennessey storage levels after the winter season have been 26,000 AF or greater more than 95 percent of the time.

In the remaining years that storage levels have been below 26,000 AF, they were at or above 24,500 AF.

For single dry years, Lake Hennessey storage is assumed to be depleted by 10,900 AFY, with another 1,400 AFY lost to evaporation and bypass flows. Therefore, Lake Hennessey has 9,500 AFY of usable supply in single dry years . Milliken Reservoir is assumed to start at 400 AF of storage and be drawn down 25 percent (100 AF) during single dry years. Therefore, the total available supply from the City’s reservoirs during a single dry year is equal to 9,600 AFY.

In the multiple dry year case, the local reservoirs were assumed to draw down by 50 percent over five years. Lake Hennessey was assumed to have a first-year depletion of 6,500 AF (i.e., 25 percent). This initial depletion of 25 percent would be followed by four years at 6.25 percent per year to reach the 50 percent drawdown by the fifth year . These depletion amounts are conservatively high er than what actually occurred in 1987-1992, when the n et depletion over that period was just 3,500 AF for Lake Hennesse y.

For Milliken Reservoir, the 50 percent storage drawdown was assumed to be spread evenly over the five years (i.e., 10 percent per year).

Table 7-2 summarizes the estimated reservoir depletion and resulting available supply for single dry years and five consecutive dry years.

Table 7-2. Estimated Local Reservoir Annual Depletion
Source
Annual Depletion, AFY
Single Dry
Year
Multiple
Dry Year 1
Multiple Dry
Year 2
Multiple Dry
Year 3
Multiple Dry
Year 4
Multiple Dry
Year 5
Lake Hennessey(a) 10,900 6,500 1,625 1,625 1,625 1,625
Milliken Reservoir(b) 100 40 40 40 40 40
Evaporation/Bypass (1,400) (1,400) (1,400) (1,400) (1,400) (1,400) Available Supply 9,600 5,140 265 265 265 265
(a) Assumed to start with 26,000 AF remaining storage after normal year. (b) Assumed to start with 400 AF remaining storage after normal year.

Table 7-3 summarizes the available local surface water supplies for each year type by combining the estimated reservoir yields (Table 7-1) and usable depletion (Table 7-2). In single dry years, 66 percent of the normal local surface water supply would be available. During a five -consecutive-year drought, available local surface water supplies range from 32 percent to 58 percent of normal. As discussed in Chapter 6, under future conditions (2045 and 2050), the availability of local surface water supplies is projected to be reduced by 11 percent to match the climate change impacts projected for the SWP.

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Table 7-3. Basis of Water Year Data – Local Surface Water (DWR Table 7-1 Retail)

7.1.2.2 Basis of Water Year Data – SWP
The ability of the SWP to deliver water to its contractors in any given year depends on several factors, including rainfall, size of snowpack, runoff, water in storage, and pumping capacity in the Delta.

Endangered fish species and Delta water quality are also significant factors affecting SWP deliveries. The actual delivery, or yield, varies from y ear to year and is described as a percentage of the contractual entitlement. For the City, annual SWP deliveries are a percentage of Table A water. While this entire entitlement may be available in wet years, lesser amounts are delivered in average, single dry, and multiple dry years. As presented in Chapter 6 of this plan, the City’s full Table A entitlement is 21,900 AFY.

SWP reliability is based on analysis performed by DWR in its 20 25 Draft DCR. Supply projections under existing and future conditions are based on conservative assumptions of climate and hydrology, while also accounting for BiOps and water quality objectives (e.g., salinity). DWR estimates the SWP’s future water delivery capability as percentages of the maximum Table A amount under multiple risk-informed climate scenarios (50%, 75%, and 95% Level-of-Concern) for the year 2043.

Results from the 50% Level-of-Concern scenario have been utilized for this plan for future 2045 and 2050 projections. This scenario reflects what DWR terms as a “middle-of-the-road” future for the SWP around the year 2043. It assumes moderately warmer and wetter conditions, including about a 2.7°F rise in average temperature, slightly more overall rainfall, more intense heavy rain events, and about 6 inches of sea level rise at the Golden Gate. It also assumes today’s land use and water-management rules stay the same, without accounting for newer agreements or ongoing regulatory updates. Because this represents an average outcome, there is about a 50 percent chance that real 2043 conditions could be better or % of Average Supply
Average Year 1922-2021 100%
Single-Dry Year 2021 66%
Consecutive Dry Years 1st Year 1987 58%
Consecutive Dry Years 2nd Year 1988 32%
Consecutive Dry Years 3rd Year 1989 32%
Consecutive Dry Years 4th Year 1990 32%
Consecutive Dry Years 5th Year 1991 32%
Year Type
Base Year
If not using a
calendar year, type in
the last year of the
fiscal, water year, or
range of years, for
example, water year
2024-2025, use 2025
Available Supplies if
Year Type Repeats
Check the box if quantification of available supplies is not compatible with this table and is provided
elsewhere in the UWMP.

Location: [insert location from UWMP]
Quantification of available supplies is provided in this table as either volume only, percent only, or both.

Volume Available (AF)
18,200
12,000
10,640
5,765
5,765
5,765
5,765
NOTES: Multiple versions of DWR Table 7-1 are used; this table is for Local Surface Water supplies only (Lake Hennessey and Milliken Reservoir) based on existing conditions through 2040. Future (2045 and 2050) conditions are assumed to be reduced by 11% to match climate change impacts assumed for the SWP.

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worse than this scenario. However, it is considered a reasonable and typical future scenario suitable for future planning considering reasonably foreseeable changes.

Based on the 2025 Draft DCR, projected deliveries from the SWP are summarized as follows:
• Normal (Average) Year:
— Existing Conditions: 54 percent (based on 1922-2021 average) — Future (2043) 50% Level-of-Concern Scenario: 48 percent (based on 1922-2021 average) • Single Dry Year:
— Existing Conditions: 10 percent (based on 2021)
— Future (2043) 50% Level-of-Concern Scenario: 8 percent (based on 2021) • Multiple-Year Drought:
— Existing Conditions: 22 percent (based on 1987-1992)
— Future (2043) 50% Level-of-Concern Scenario: 15 percent (based on 1987-1992) To further emphasize a conservative approach for its SWP reliability, the City will assume the following are unavailable: carryover water, NOD Allocation, Article 21 water, and Dry Year water. In the single dry and multiple dry year cases, the City assumes that carryover water would be exhausted, so the City can receive an additional 3,772 AFY in Advanced Table A water (in addition to its Table A allocation). Table 7-4 summarizes the assumptions for SWP supply reliability used in this plan.

Table 7-4. State Water Project Reliability Assumptions
Water Year Type Table A(a), percent Table A, AFY
Advanced Table A(b),
AFY
Total SWP Deliveries,
AFY
Existing Conditions (through 2040)
Normal 54% 11,826 -- 11,826
Single Dry 10% 2,190 3,772 5,962
Multiple Dry 22% 4,818 3,772 8,590
Future Conditions (2045 and 2050)
Normal 48% 10,512 -- 10,512
Single Dry 8% 1,752 3,772 5,524
Multiple Dry 15% 3,285 3,772 7,057
(a) 100 percent Table A is 21,900 AFY. Assumed reliability is based on Table 6-2 of the 2025 Draft DCR for existing conditions (through 2040) and future (2043) conditions under the 50% Level-of-Concern (LOC) Scenario (for 2045 and 2050). (b) Carryover water is assumed to be exhausted, so the City is entitled to Advanced Table A water. Refer to Sections 6.2.1 and 6.2.3.

Table 7-5 presents the basis of water year data for the City’s SWP supplies and calculates the volumes available as a percentage of a normal year’s supply.

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Table 7-5. Basis of Water Year Data – State Water Project (DWR Table 7-1 Retail)

7.1.3 Water Service Reliability
This section presents comparisons of projected water supplies and demands from 20 30 through 2050 under the following hydrologic conditions: normal year, single dry year, and five consecutive dry years. It should be noted that water year types do not necessarily coincide between local reservoirs and the SWP.

For example, a normal rainfall year in the Lake Hennessey watershed may occur during a dry year for the SWP watershed. However, this plan assumes that dry years occur simultaneously in both the local surface water and SWP supplies for a more conservative estimate of supply reliability.

Unless otherwise noted, it is assumed demand projections will not change with hydrologic conditions. In other words, demands are assumed to be unconstrained unless they are limited by available supplies.

7.1.3.1 Water Service Reliability – Normal Year
The City’s normal water year supplies include local surface water stored in Lake Hennessey and Milliken Reservoir and imported water from the SWP. Table 7-6 shows that in normal years, the City’s supplies are adequate to meet projected demands.
% of Average Supply
Average Year 1922-2021 100%
Single-Dry Year 2021 50%
Consecutive Dry Years 1st Year 1987 73%
Consecutive Dry Years 2nd Year 1988 73%
Consecutive Dry Years 3rd Year 1989 73%
Consecutive Dry Years 4th Year 1990 73%
Consecutive Dry Years 5th Year 1991 73%
Year Type
Base Year
If not using a
calendar year, type in
the last year of the
fiscal, water year, or
range of years, for
example, water year
2024-2025, use 2025
Available Supplies if
Year Type Repeats
Check the box if quantification of available supplies is not compatible with this table and is provided
elsewhere in the UWMP.

Location: [insert location from UWMP]
Quantification of available supplies is provided in this table as either volume only, percent only, or both.

Volume Available (AF)
8,590
8,590
NOTES: Multiple versions of DWR Table 7-1 are used; this table is for State Water Project supplies only based on existing conditions through 2040. Future (2045 and 2050) conditions are based on the Draft 2025 DCR 50% Level-of-Concern Scenario. 11,826
5,962
8,590
8,590
8,590
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Table 7-6. Normal Year Supply and Demand Comparison
(DWR Table 7-2 Retail)

7.1.3.2 Water Service Reliability – Single Dry Year
As shown in Table 7-7, in single dry years following a normal year the City’s supplies are adequate to meet projected demands through 2050.

Table 7-7. Single Dry Year Supply and Demand Comparison (DWR Table 7-3 Retail)

7.1.3.3 Water Service Reliability – Five Consecutive Dry Years Table 7-8 shows that the City’s supplies are adequate to meet projected demands during five -year droughts beginning in 2030, 2035 and 2040. For extended droughts beginning in 2045 and 2050, supply deficits of 16 to 18 percent are anticipated beginning in the second year. Stage 2 of the WSCP would likely need to be implemented to reduce water demands. Supply augmentation with Dry Year water purchases could also be employed.
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF)
Supply totals
(autofill from Submittal Table 6-9 R) 30,026 30,026 30,026 26,710 26,710 Use totals
(autofill from Submittal Table 4-2 R) 13,560 14,035 14,110 14,510 14,810 Surplus/(shortfall) 16,466 15,991 15,916 12,200 11,900
Supply totals 17,962 17,962 17,962 16,204 16,204
Use totals 13,560 14,035 14,110 14,510 14,810
Surplus/(shortfall) 4,402 3,927 3,852 1,694 1,394
2050 (AF)
NOTES: For 2045 and 2050, Local Surface Water supply totals incorporate an 11% reduction due to assumed long-term climate change impacts. 2045 and 2050 State Water Project supply totals incorporate reductions based on the 50% Level of Concern under Future Climate Change Conditions.
2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF)
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Table 7-8. Multiple Dry Years Supply and Demand Comparison (DWR Table 7-4 Retail)

7.1.4 Water Management Tools and Options
To maximize the use of local water resources and minimize the need to import water from other regions, the City focuses on demand reduction, specifically prioritizing water use efficiency and conservation and encouraging recycled water use where available . Chapter 9 of this plan details the City’s water use efficiency and conservation efforts.

Also, as described in Chapter 6, the City is exploring a number of potential future water supply projects, including WTP improvements and options, to increase future water supplies.

7.2 DROUGHT RISK ASSESSMENT
In accordance with CWC Section 10612, urban water suppliers must conduct a Drought Risk Assessment (DRA), which evaluates the risk of a severe drought occurring for the next five consecutive years (2026-2030). Supply conditions for the DRA are based on what would be the five driest consecutive years on record.

This section reviews the data and methods used to define the DRA water shortage condition and evaluates each water source’s reliability under the proposed drought condition. Finally, total water supplies during the five-year drought are compared to projected demands.

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7.2.1 Data, Methods, and Basis for Water Shortage Condition Since the DRA can be updated independently from the five-year UWMP cycle, a summary of the data and basis for the water shortage condition is provided in this section . The basis for the water shortage condition for a five-year drought starting in 2026 and continuing through 2030 is the same as assumed for the multiple dry year described above.

The City’s local surface water supplies from Lake Hennessey and Milliken Reservoir yield are based on their estimated multiple dry year yield (see Table 7 -1) and estimated annual depletion in multiple dry years (see Table 7-2).

SWP reliability is assumed to be 22 percent of the maximum Table A amounts (21,900 AFY for the City) .

In all five years of the DRA, the City assumes that carryover water would be exhausted, so the City can receive at least 3,772 AFY in Advanced Table A water (in addition to its Table A allocation).

7.2.2 DRA Water Source Reliability
The City’s multiple dry year supplies include local surface water (i.e., reservoir yield and depletion) and SWP imports. The City’s local surface water availability is based on estimated multiple dry year yield and annual depletion. The 2026 to 2030 SWP allocation is assumed to be 22 percent with Advanced Table A supply available in each year.

Table 7-9 summarizes the available supplies for each year of the DRA by supply source.

Table 7-9. Projected Supplies for Drought Risk Assessment Supply Source
Available Supply, AFY
2026 2027 2028 2029 2030
Lake Hennessey(a) 10,640 5,765 5,765 5,765 5,765 Milliken Reservoir(a) SWP Table A(b) 4,818 4,818 4,818 4,818 4,818
SWP Carryover 0 0 0 0 0
SWP Article 21 0 0 0 0 0
SWP Advanced Table A 3,772 3,772 3,772 3,772 3,772
Dry Year Purchases/
Other Water 0 0 0 0 0
Total 19,230 14,355 14,355 14,355 14,355
(a) Sum of multiple dry year yield and depletion. Refer to Table 7-1 and Table 7-2. (b) The SWP Table A allocation is assumed to be 22 percent for 2026 to 2030, assuming multiple dry year conditions.

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7.2.3 Total Water Supply and Use Comparison
As shown in Table 7-10, during a five -year drought beginning in 202 6 and continuing through 2030, the City is projected to have adequate supplies to meet the projected demand.

Table 7-10. Five-Year Drought Risk Assessment
(DWR Table 7-5 Retail)

2026 Total
Total Water Use (AF) 12,481
Total Supplies (AF) 19,230
Surplus/Shortfall w/o WSCP Action 6,749
2027 Total
Total Water Use (AF) 12,751
Total Supplies (AF) 14,355
Surplus/Shortfall w/o WSCP Action 1,604
2028 Total
Total Water Use (AF) 13,020
Total Supplies (AF) 14,355
Surplus/Shortfall w/o WSCP Action 1,335
2029 Total
Total Water Use (AF) 13,290
Total Supplies (AF) 14,355
Surplus/Shortfall w/o WSCP Action 1,065
2030 Total
Total Water Use (AF) 13,560
Total Supplies (AF) 14,355
Surplus/Shortfall w/o WSCP Action 795
NOTES: Water Use is based on slight annual increase in demands based on population growth and new development. Supplies are based on the 1987-1992 Multiple Dry Year scenario reflected in DWR Tables 7-1 and 7-4.

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CHAPTER 8
Water Shortage Contingency Plan
This chapter presents the City’s Water Shortage Contingency Plan (WSCP), water supply reliability analysis summary, seismic risk assessment and mitigation plan, and WSCP adoption procedures. This chapter describes the City’s WSCP, which is included as Appendix J to allow for updates independent of the UWMP preparation process.

8.1 WATER SHORTAGE CONTINGENCY PLAN BACKGROUND
Water shortages occur whenever the available water supply cannot meet the normally expected customer water use. This can be due to several reasons, including climate change, drought, and catastrophic events.

Drought, regulatory action constraints, and natu ral and manmade disasters may occur at any time. A WSCP presents how an urban water supplier plans to respond to a water shortage condition and helps prevent catastrophic service disruptions.

In 2018, the California State Legislature enacted two policy bills, (SB 606 (Hertzberg) and AB 1668 (Friedman)) (2018 Water Conservation Legislation), to establish a new foundation for long -term improvements in water conservation and drought planning to adapt to climate change and the resulting longer and more intense droughts in California. The 2018 Water Conservation Legislation set new requirements for water shortage contingency planning; the City’s WSCP has been updated to be consistent with these requirements.

8.2 WATER SHORTAGE CONTINGENCY PLAN
The City’s WSCP is included in this plan as Appendix J and describes the City’s strategic plan for preparing and responding to water shortages. Chapter 13.10 of the Napa Municipal Code (NMC) supports the City’s WSCP actions.

The WSCP includes water shortage stages and associated shortage response actions, as well as the City’s legal authorities, communication protocols, compliance and enforcement, and monitoring and reporting.

The City intends for its WSCP to be dynamic, so that it may assess response action effectiveness and adapt to foreseeable and unforeseeable events. It may also be updated to conform to State legislative and regulatory requirements. Therefore, the City’s WSCP is included in this plan as an appendix to allow for updates to be made outside of the UWMP preparation process. When an update to the WSCP is proposed, the revised WSCP will undergo the process described in Section 8.5.

8.3 WATER SUPPLY RELIABILITY ANALYSIS SUMMARY
Chapters 6 and 7 present the City’s water supply sources and reliability, respectively. Findings show the City can reliably meet its projected demands through 20 50 in normal hydrologic conditions, as well as single dry year conditions. In multiple dry year scenario s beginning in 2045 and 2050 , supply shortfalls can be eliminated by reducing demand with the appropriate stage of this WSCP.

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Statewide water supply conditions and actions by other agencies may impact the City’s available water supply. A water shortage condition occurs when the available supply of potable water cannot meet ordinary water demands for human consumption, sanitation, fire protection, and other beneficial uses. In some cases, t he City may foresee a water shortage, but the water shortage may also be caused by an unforeseen sudden or emergency event. In general, the City’s water supply conditions may be affected by the following:
• Local surface water availability (Lake Hennessey and Milliken Reservoir yields and available storage for drawdown in dry years)
• State Water Project (SWP) annual supply allocations
• Sacramento-San Joaquin Delta (Delta) and North Bay Aqueduct vulnerability to seismic events, changing environmental and regulatory requirements, and climate change • Climatic variability and drought conditions
The City plans for potential drought events annually by conducting an annual water supply and demand assessment in accordance with its WSCP to determine its water supply conditions for the current year and a potential subsequent dry year.

In addition to hydrologic and regulatory supply constraints, seismic events pose a significant risk to water supply reliability due to the potential for infrastructure damage and resulting supply interruptions. Given California’s high seismic activity and the likelihood of future earthquakes, UWMPs are required to include a seismic risk assessment and mitigation plan. The City’s seismic risk assessment and mitigation planning efforts are described in the section below.

8.4 SEISMIC RISK ASSESSMENT AND MITIGATION PLAN
CWC Section 10632.5(a) requires that UWMPs include a plan to assess and mitigate a water system’s seismic vulnerabilities. The City’s Hazard Mitigation Plan Update1 (City HMP Update, updated in 2022 ) meets this requirement because it addresses seismic risk. It is incorporated into this plan by reference .

The City HMP Update was submitted to the Federal Emergency Management Agency (FEMA), which found it in conformance with Title 44 Code of Federal Regulations Part 201.6 Local Mitigation Plans.

While California experiences hundreds of earthquakes each year, most are below magnitude-3.0 and cause minimal damage. The United States Geological Survey (USGS) roughly defines strong earthquakes (which can cause moderate damage to structures) as measuring greater than magnitude-5.0, while major earthquakes measure more than magnitude-7.0.

The City is in a seismically active region. In August 2014, a magnitude-6.0 earthquake centered in South Napa caused significant damage throughout the region, including numerous water main breaks. The West Napa Fault runs along the western edge of the City, while the Rodgers Creek Fault and Green Valley/Concord Fault run through the County. A 2016 report2 by the USGS estimated the probabilities for magnitude-6.7 (or larger) earthquakes on major fault lines in the San Francisco Bay Area by the year 2043. The Rodgers Creek Fault

1 City of Napa, 2022. Hazard Mitigation Plan Update.
https://www.cityofnapa.org/DocumentCenter/View/12156/City-of-Napa-Hazard-Mitigation-Plan-2022?bidId= 2 U.S. Geological Survey (USGS), 2016. Earthquake Outlook for the San Francisco Bay Region 2014-2043. https://pubs.usgs.gov/fs/2016/3020/fs20163020.pdf
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has a 33 percent chance of one or more earthquakes of magnitude-6.7 or larger by 2043, while the Green Valley/Concord Fault has a 16 percent chance of one or more such earthquakes in that timeframe.

The City HMP Update identifies risks posed by disasters (including earthquakes) and ways to minimize damage from those disasters. To promote an earthquake-safe community, the City HMP Update proposes two objectives: (1) continue requiring all new buildings and infrastructure to be designed and constructed to resist earthquake stresses; and (2) identify options, incentives, and funding sources for retrofitting seismically vulnerable structures. Each objective is associated with implementation actions, many of which the City is already implementing. The implementation actions relevant to the City’s water system include:
• Discourage locating facilities necessary for emergency services and major utility lines and facilities within areas subject to strong or violent ground shaking. • Require that facilities necessary for emergency services be capable of withstanding a maximum credible earthquake from any of the seven known active faults in the region and remaining operational to provide emergency response.
• Design and install seismic-resistant transmission and distribution pipeline joints across known faults and on newly constructed bridges.
• Invest in automation and control features on asbestos cement transmission pipeline to protect against catastrophic failures.

To address the seismic vulnerabilities of its water system facilities, the City has completed a Risk and Resilience Assessment (RRA) of its water system. Completed in accordance with America’s Water Infrastructure Act, the RRA systematically evaluated the City’s assets, threats, and risks, as well as countermeasures that might be implemented to minimize overall risk to the system. To ensure the security of the City’s water system, the RRA is retained by the City as a confidential document.

8.5 WATER SHORTAGE CONTINGENCY PLAN ADOPTION, SUBMITTAL, AND

AVAILABILITY
The City’s WSCP ( Appendix J) is adopted concurrently with this plan, by separate resolution. Prior to adoption, a duly noticed public hearing was conducted. An electronic copy of the WSCP will be submitted to DWR within 30 days of adoption.

No later than 30 days after adoption, a copy of this WSCP will be available at the City’s offices. A copy will also be provided to Napa County. An electronic copy of the WSCP will also be available for public review and download on the City’s website.

The City’s WSCP is an adaptive management plan and is subject to refinements as needed to ensure that the City’s shortage response actions and mitigation strategies are effective and produce the desired results. When a revised WSCP is proposed, the revised WSCP will undergo the process described above for adoption by City Council and distribution to Napa County, the City’s customers, and the general public.

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CHAPTER 9
Demand Management Measures
This chapter describes the City’s historical and existing water conservation efforts, status of implementation of Demand Management Measures (DMMs), and projected future water conservation implementation.

9.1 WATER CONSERVATION PROGRAM OVERVIEW
Water use efficiency and conservation has been and will continue to be an integral part of the City’s long-term water supply management strategy. T he City first instituted successful demand reduction measures during the drought of 1987 -1992, after which the City made several of those measures permanent, including school education, public information, and a very successful toilet replacement program that continued for three decades. The City’s strategy for water use efficiency and conservation includes: (1) offering existing customers an array of free services, rebates, and education so that older high water use equipment and behaviors are replaced with more water efficient ones; and (2) maximizing the water efficiency of new development to minimize its impact on the City’s future water demands.

In 2002, the City joined the California Urban Water Conservation Council, which has now evolved into the California Water Efficiency Partnership (CalWEP). CalWEP seeks to maximize urban water efficiency and conservation statewide using innovative technologies and practices and effective public policy, all within a collaborative framework.

The City’s SB X7 -7 per capita water use target for 2020 was 132 GPCD. In 2020, the City’s overall per capita water use was 137 GPCD and did not meet this target. In 2025, the City’s overall per capita water use was 119 GPCD and met its per capita water use target, partly due to the DMMs it implemented. The City will continue to expand its water conservation efforts to meet its Urban Water Use Objective (UWUO) and other measures in the Making Conservation a California Way of Life Regulation (AB 1668 and SB 6 06) finalized in 2024.

9.2 EXISTING AND PLANNED DEMAND MANAGEMENT MEASURES
Retail water agencies are required to provide a description of the DMMs associated with the following:
• Water Waste Prevention Ordinances
• Metering
• Conservation Pricing
• Public Education and Outreach
• Programs to Assess and Manage Distribution System Real Loss • Water Conservation Program Coordination and Staffing Support The City is also required to describe any other DMMs that it has implemented that have had significant impact on water use.

This section describes the existing and planned DMMs. For each DMM, the current program is described, along with how the DMM was implemented over the previous five years and future implementation plans.

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9.2.1 Water Waste Prevention Ordinances

9.2.1.1 DMM Description
NMC Chapter 13.09 lays out regulations to eliminate wasteful water -using practices within the City’s service area. Specific water waste prohibitions are enforced via administrative citations issued by the Utilities Director, with repeated violations subject to escalating fines.

9.2.1.2 Implementation over the Past Five Years to Achieve Water Use Targets Following the end of the 20 21-2023 statewide and local drought emergency, the City applied lessons learned during the drought to clarify and update its permanent water waste prohibitions. Adopted by City Council in June 2023, the water waste prohibitions in NMC Chapter 13.09 address open-ended hose use, driveway and sidewalk washing, wasteful irrigation practices, and significant leaks. The City’s Water Conservation Specialist follows up on all water waste complaints, using educational warnings as a first method to change behavior. During a declared drought, additional staff routinely patrol for violations.

The City also has in place local ordinances to ensure water efficient design in new development. Local high-performance building regulations are more stringent than CALGreen, making several voluntary provisions mandatory and requiring a more stringent tier of indoor water use savings for non-residential buildings. The City aggressively enforces the statewide Model Water Efficient Landscape Ordinance (MWELO) to prevent outdoor water waste in new development.

9.2.1.3 Plans for Continued Implementation
The City will continue to enforce its water waste prohibitions through public education and fines when warranted. The effectiveness of water waste prevention will be evaluated based on the number of violations, as well as the overall demand reduction after declaring a water shortage.

Implementation of this DMM is ongoing and expected to help the City achieve its water use targets by minimizing the nonessential uses of water so that water is available to be used for human consumption, sanitation, and fire protection.

9.2.2 Metering

9.2.2.1 DMM Description
The City’s water system is fully metered. Excluding fire sprinkler services, all existing connections have meters and are billed by volume of use. The City employs Automatic Meter Reading (AMR) throughout the entire system and will be transitioning to Advanced Metering Infrastructure (AMI) over the next decade. For the AMR meters equipped with Encoder Receiver Transmitters (ERTs), City staff perform drive-by meter readings via radio, which significantly reduces the time required for meter reading. After each meter read cycle, the City can quickly alert customers with exceptionally high usage compared to previous years. These alerts often lead customers to discover and repair leaks more quickly.

Newer meters preserve 40 days of historical water usage data that can be analyzed in hourly intervals.

These data can assist customers in determining the timing and reason for their unexpected high usage.

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9.2.2.2 Implementation over the Past Five Years to Achieve Water Use Targets Over the past five years, the City has leveraged its fully metered system to support achievement of its water use targets. Meter data are reviewed each billing cycle to identify unusually high consumption, and customers are proactively notified to investig ate potential leaks or inefficiencies, resulting in timely repairs and reduced water loss. The City also evaluates systemwide production data against billed consumption to support water loss control and efficient system operations, strengthening overall demand management and compliance with water use efficiency requirements.

9.2.2.3 Plans for Continued Implementation
The City requires all new connections to be metered and billed based on the volume of water used, as detailed in Section 9.2.3. The City will monitor water usage characteristics of its customers and focus water conservation efforts on high water users. Current plans include the establishment of a networked AMI system that will provide early leak detection for customers and more extensive water use data to inform the City’s water conservation priorities.

9.2.3 Conservation Pricing

9.2.3.1 DMM Description
The City’s water rate structure encourages conservation by incorporating a water quantity (i.e., volumetric) charge in addition to a fixed service charge. Consequently, water usage reductions directly reduce customer costs, while excessive water use increases costs. In addition, water rates for single-family residential customers are tiered, with higher usage tiers paying higher rates. There is no tiered rate structure for multi-family residential, commercial/industrial/institutional, or irrigation customers.

9.2.3.2 Implementation over the Past Five Years to Achieve Water Use Targets The City’s 2025 water rate schedule is shown in Table 9-1. As previously noted, besides the water quantity charge, the City also has a fixed bimonthly service charge that varies with service size and applies to all customer classes. Water quantity charges are higher for customers served outside City limits and f or customers in certain high -elevation zones (to cover pumping costs). The current rate structure was adopted by the City Council in 2023 and included five years of automatic annual increases. No spe cial drought rates were used in the recent 2012 -2016 drought. However, the City can establish a special drought block rate structure by resolution during severe droughts.

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Table 9-1. City of Napa Current Water Rate Schedule
Service Size/Customer Class
Inside City Rate(a)
dollars
Outside City Rate(a)
dollars
Bimonthly Fixed Service Charge – All Customer Classes (Excluding Fire Services) 3/4-inch 63.53
1-inch 63.53
1 1/2-inch 121.51
2-inch 191.07
3-inch 376.56
4-inch 585.24
6-inch 1,164.91
8-inch 2,092.39
Water Quantity Charge(b)
Single-Family Residential(c)
0-14 units 6.67 9.85
15-27 units 9.82 14.08
28+ units 11.92 15.53
Multi-Family Residential 9.27 13.64
Commercial/Industrial/Institutional 9.25 13.55
Irrigation 9.34 13.76
Pumped Zone Customers(d) 3.00
(a) Water rate schedule (as of October 1, 2025) from City of Napa website. Water quantity charges are higher for customers located outside City limits.
(b) Water quantity charge is cost per unit, where 1 unit = 1,000 gallons. (c) Single-family residential usage is tiered, with higher usage tiers charged higher rates. (d) Elevation surcharge (i.e., in addition to water quantity charge) for customers in pumped zones.

9.2.3.3 Plans for Continued Implementation
Implementation of this DMM is expected to help the City achieve its water use objectives. As required, the City will evaluate the need to readjust rates and/or rate structures to ensure continued service to its customers while encouraging water efficiency. In 2028, the City is planning to conduct a new rate study, which will inform the next iteration of water rates. The City will evaluate the effectiveness of its rates by tracking changes in unit water use resulting from rate increases.

9.2.4 Public Education and Outreach

9.2.4.1 DMM Description
The City regularly promotes water efficiency and conservation and educates the community through its website (cityofnapa.org/water), messaging on bimonthly water bills, and fliers and brochures available at both the Utilities Department office and at public events. Media coverage of the City’s water conservation program is provided through local newspaper, magazine, and radio adverti sements and interviews. City ATTACHMENT 3

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staff also deliver presentations to community and business groups, as well as make appearances at local public events such as Earth Day, Napa Farmers Market, and Napa Town & Country Fair.

9.2.4.2 Implementation over the Past Five Years to Achieve Water Use Targets As part of its school education program, the City continues its active membership in the Environmental Education Coalition of Napa County (EECNC), which organizes the local Earth Day event, awards scholarships, distributes field trip bus grants, and publicizes water education offerings to area K -12 teachers. Over the past five years , City water conservation education and outreach was inhibited somewhat by the pandemic, but offerings beyond the regular appearances at community events included:
• Water Education Assembly. Since the 2016-17 school year, the City has contracted with the group ZunZun to present musical assemblies for elementary school students that focus on where their water comes from, water conservation, and climate change. ZunZun's bilingual programs are always lively, with students and teachers singing and playing a variety of folkloric instruments. From 2021 to 2025, ZunZun conducted 95 virtual and in-person assemblies attended by nearly 19,000 students.
• Water Treatment Plant Field Trip. City staff provide tours of the Barwick Jamieson WTP, either separately or as part of a combined full-day trip in conjunction with the Napa Recycling & Composting Facility and NapaSan’s Soscol WRF. The tours include an introductory discussion, plant tour, and drinking water-related giveaways for students. Bus transportation costs are covered by the City and its partners. Student visits to the treatment plant were eliminated during the pandemic and did not resume until early 2026. • Project WET (Water Education for Teachers). Napa County teachers can gain access to award-winning classroom activities and earn a stipend or 0.5 continuing education units by participating in Project WET for the Napa Valley, which consists of six hours of hands-on, action-packed training. Project WET promotes awareness, appreciation, knowledge, and stewardship of water resources through the dissemination of classroom-ready teaching aids.

Interdisciplinary activities for grades K-12 are designed to enhance existing curriculum and are aligned to Common Core State Standards. Since the first offering in 2012, the City has certified more than 30 local teachers in this curriculum. While no trainings have been conducted in the past five years, the City and its local partners will resume this program. • High School Video Contest. Starting in the 2015-16 school year, the City has been instrumental in organizing the Napa County Water Conservation Video Contest by developing annual themes and judging the winning entries. The contest is open to all local students in grades 9-12, and the annual winning video is posted online and played before films at a local theater, thereby extending the water conservation outreach.

The City routinely advertises in the Napa Valley Marketplace magazine, which is mailed out to 33,000 local homes and business es every month . For the 2021-2025 period, more than 70 ads with a water conservation theme were placed. At public events, the City hosts a display booth that reaches thousands of water customers via educational literature, free water -saving device giveaways, and direct questions answered by the City’s Water Conservation Specialist.

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9.2.4.3 Plans for Continued Implementation
The City will continue to implement the public education and outreach strategies described above.

Implementation of this DMM is expected to help the City achieve its water use targets by educating water users about the value of water, the importance of improving water use efficiency, and avoiding water waste.

9.2.5 Programs to Assess and Manage Distribution System Real Loss

9.2.5.1 DMM Description
The City performs an annual water audit that conforms to the AWWA Manual M36 and is required by state regulations . A water audit is a process of calculating water use throughout a water system to quantify the unaccounted -for water (i.e., the difference between metered production and metered consumption on a system -wide basis ) and establish estimates for both real losses ( e.g., leaks) and apparent losses (e.g., metering inaccuracies). The City is required to have its annual AWWA Water Audit validated and submitted to DWR.

The City responds promptly to visible water main and service line leaks to minimize losses. For less obvious leaks, the City may contract with leak detection professionals to use sonic methods. In addition, the City provides financial incentives for customers to promptly repair leaks on their side of the meter.

9.2.5.2 Implementation over the Past Five Years to Achieve Water Use Targets The City has used AWWA’s free audit software (Excel) to thoroughly document its distribution system attributes and performance indicators related to water loss. Annual electronic calibration of source meters and other improved practices over the years have increased the reliability of this audit data. The Water Audit Data Validity Score has remained in the 70s since 2020, putting the City in Tier IV (of V). For 2024, the City calculated 1,013 AF of combined real and apparent losses. The key performance indicator is real losses per service connection per day, which was 22.4 gallons per service connection per day in 2024, just under the 2028 State Water Board standard of 26.8.

9.2.5.3 Plans for Continued Implementation
Implementation of this DMM is ongoing and is a vital element of the City’s water supply management efforts. By quickly identifying sources of water loss, the City can promptly make repairs and minimize losses.

The City will continue to improve its annual AWWA Water Audit process and work to reduce its real and apparent losses to meet the State Water Board standards. Accelerated replacement of older water mains and meters will assist this effort. Conducting a real loss component analysis will also help guide the City’s efforts in an economically efficient manner. Water supplier-specific performance standards for real losses per connection per day are in development and will guide the City’s efforts to control leaks within its distribution system.

9.2.6 Water Conservation Program Coordination and Staffing Support

9.2.6.1 DMM Description
The City designates its Water Resources Analyst as its Water Conservation Coordinator, with 65 percent of the position's duties budgeted to managing and developing the DMMs described in this chapter. The Water Conservation Coordinator is a Level 3 Water Use Efficiency Practitioner and a Certified Landscape Irrigation Auditor.

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A full-time Water Conservation Specialist supports the water conservation program by providing direct customer service in the field and assisting with program development and development plan review .

Other Water Division staff assist as needed, including service workers who alert customers of excessive use and office staff who help at large public events.

9.2.6.2 Implementation over the Past Five Years to Achieve Water Use Targets Over the past five years, the City has maintained the Water Conservation Coordinator and Water Conservation Specialist positions to execute the DMMs described in this chapter. The City’s annual water conservation budget has increased to about $600,000, including personnel. Some of these costs are offset through grant funding and shared rebate costs with other agencies.

9.2.6.3 Plans for Continued Implementation
The City plans to maintain the Water Conservation Coordinator and Water Conservation Specialist positions, while adding a part -time employee to assist with school education and multi -family and commercial programs. Implementation of this DMM is ongoing and expected to help the City achieve its water use targets by making water conservation and implementation of the City’s water conservation program a priority among City employees.

9.2.7 Other Demand Management Measures
In addition to the DMMs described above, the City implements the following programs:
• Water conservation services
• Rebate programs
• Commercial, industrial, and institutional (CII) conservation programs • Water Offset Program
Each program is described below, along with a summary of implementation over the past five years and plans for continued implementation.

9.2.7.1 Water Conservation Services

9.2.7.1.1 DMM Description
The City offers several water conservation services to the public, as described below. These services are offered at no cost to customers and are complemented by the City’s rebate programs, which are described in Section 9.2.7.2.
• Water-Wise Home Survey. Marketed to all single family and multi-family residential customers, this program includes a site visit by the Water Conservation Specialist who checks leaks, plumbing fixture flow rates, and irrigation system performance. If warranted, customers are offered free low-flow showerheads, faucet aerators, rebate information, and irrigation scheduling and maintenance tips.

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• Free Water-Saving Devices. City water customers are entitled to an array of free water conservation devices, such as low-flow showerheads, faucet aerators, garden hose nozzles, and hose timers. The materials can be obtained from the Utilities Department office, at public events, or as part of a Water-Wise Home Survey.
• Water-Wise Gardening in the Napa Valley website (napa.watersavingplants.com). This website contains an extensive landscape photo and plant information database, along with a gardening and irrigation guide appropriate for the local climate. • Water-Wise Landscaping Workshop Series. This is an annual program to educate the public on the water-saving benefits of improved irrigation scheduling, drip irrigation, soil amendments, mulch, and climate-appropriate plant selection. The City benefits from strong partnerships with the Napa County Resource Conservation District (RCD) and the University of California Master Gardeners of Napa County in putting on these workshops, and the City sometimes co-sponsors the event with a nearby agency such as the Town of Yountville. • Water-Wise Demonstration Gardens. The public is welcome to visit three demonstration gardens, including a walk-through 9,000 square-foot space at Fire Station #3 featuring an array of lawn substitutes, California native plants, colorful low-water-use species, and weather-based “smart” irrigation control. The other two sites are the Vintage High School Rain Garden and Water-Wise Landscape, installed in 2013, and the former Water Division office, whose lawn was replaced with water-wise plants in the fall of 2014. The current Utilities Department office is slated for an extensive demonstration garden in the coming years. • Climate-Friendly Garden Tour. Since 2011, the City has partnered with other local agencies to offer an annual garden tour that typically features a dozen local residential, commercial, or institutional landscapes demonstrating the beauty of low-water-use design. During the pandemic, virtual tours of individual gardens were streamed. The in-person tour resumed in 2023.

9.2.7.1.2 Implementation over the Past Five Years to Achieve Water Use Targets Between 2021 and 2025:
• City staff completed 500 Water-Wise Home Surveys.
• Approximately 1,200 water-saving devices were distributed. • The Water-Wise Gardening in the Napa Valley website received more than 20,000 unique visitors.
• Eight in-person Water-Wise Landscaping workshops were held in 2024 and 2025, for a total of 210 attendees.
• More than 700 people attended the 2023-2025 Climate-Friendly Garden tours.

9.2.7.1.3 Plans for Continued Implementation
The City plans to continue the above water conservation services to meet future water use objectives.

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9.2.7.2 Rebate Programs

9.2.7.2.1 DMM Description
The City maintains rebate programs to financially incentivize its customers to improve water efficiency.

Current rebate programs include turf replacement, CII appliance upgrades, and smart water monitors. • “Cash for Grass” Turf Replacement Rebate. First introduced in 2010, this program currently offers all residential and CII customers $1.00 per square foot to replace high water use lawn areas with low-water use plants or permeable hardscape, with an extra $1.00 bonus for parking strip areas. The maximum rebate is $750 for single family residential customers and $2,500 for multi-family residential and CII customers. Projected water savings are 25 gallons per year per square foot of turf removed.
• Smart Rebates. The City participates in the CalWEP-administered Smart Rebates Program offering rebates on commercial high-efficiency clothes washers (HECWs) ($400), HETs ($200), and high-efficiency urinals (HEUs) ($300). While these rebates are intended for CII customers, multi-family residential common areas are also eligible for HECW rebates. • Smart Home Water Monitor. In 2021, the City introduced an instant rebate on the purchase of a Flume device. The Flume device allows customers to monitor their water use from their smartphone, enabling instant detection of leaks. This partnership with CalWEP and Flume allows customers to purchase the device for just $64 when it normally retails for $249. • Smart Irrigation Controller. In 2022, the City introduced an instant rebate on the purchase of a Rachio Smart Sprinkler Controller. Replacing a standard timer, this device provides weather-based self-adjusting schedules that can save up to 50% on outdoor water use. This partnership with CalWEP and Rachio currently provides City customers a 15% discount on the retail price, rising to 25% during certain promotional weeks throughout the year.

9.2.7.2.2 Implementation over the Past Five Years to Achieve Water Use Targets Over the last five years, the City issued 656 “Cash for Grass” rebates representing 505,000 square feet of turf removed, saving about 39 AFY. A limited amount of Smart Rebates were issued to commercial customers between 2021 and 2025, while more than 700 Flume devices and 200 Rachio controllers were purchased by primarily residential customers.

9.2.7.2.3 Plans for Continued Implementation
The City anticipates continuing these rebate programs to achieve its future water use objectives , depending on customer participation and available funding. The City plans to expand its partnership with CalWEP in order to offer instant rebates on additional irrigation equipment, leak monitors, and food service equipment. The Cash For Grass rebate incentive will increase and include a bonus rebate amount for rain garden areas. Additional rebates for water -efficient devices will be considered based on cost-effectiveness.

ATTACHMENT 3

Chapter 9
Demand Management Measures

N-C-424-60-26-28-WP-R-25-UWMP
9-10 City of Napa
2025 Urban Water Management Plan
May 2026

9.2.7.3 Commercial, Industrial, and Institutional Conservation Programs

9.2.7.3.1 DMM Description
The City offers its CII customers the following specialized conservation services:
• Water-Wise Business Survey. Offered to all CIl customers to help them use water more efficiently and potentially reduce operating costs, the survey consists of a water use history and billing analysis; site visit by City staff; evaluation of fixtures, appliances, and equipment; a landscape irrigation audit; and a follow-up recommendations report. • Landscape Irrigation Audits. Full landscape irrigation audits are typically conducted as part of a Water-Wise Business Survey for large commercial and institutional sites, but CII customers can also request standalone landscape irrigation audits. Results often point out simple changes in controller scheduling, sprinkler and drip emitter maintenance, and plant selection that can help improve water use efficiency.
• Green Business Stipend. Since 2013, the City has been offering a $500 stipend to local businesses that complete the Green Business Certification Program and implement a comprehensive sustainability program, including water use efficiency. • Qualified Water Efficient Landscaper (QWEL) Training. Since 2020, the City has sponsored this EPA WaterSense-certified, 20-hour training course and certification program, and offering it free of charge to local landscape professionals. The landscape professionals, and their clients, benefit from education about local water supplies, soils, landscape water budgets, irrigation system audits, and controller programming.

9.2.7.3.2 Implementation over the Past Five Years to Achieve Water Use Targets Over the past five years, the City completed several Water-Wise Business Surveys , with many CII customers participating in the Cash For Grass Rebate Program to address their irrigation use. The City trained more than 30 additional QWEL-certified landscape professionals since 2021.

9.2.7.3.3 Plans for Continued Implementation
The City plans to continue the above CII conservation programs to meet future water use objectives , particularly in the landscape irrigation area to incentivize CII customers affected by AB 1572, the upcoming phased-in bans on the use of drinking water to irrigate non-functional turf.

9.3 CALIFORNIA WATER EFFICIENCY PARTNERSHIP
The City is an active member of the CalWEP , establishing a firm commitment to the implementation of DMMs to conserve its water supplies. The City plans to continue implementation of its DMMs into the future. The City also plans to comply with the State Water Board’s Making Conservation a California Way of Life Regulation to meet its U WUO and to meet its water loss performance standards .

Other DMMs may be implemented by the City as deemed necessary based on customer participation, water savings, cost effectiveness, and other relevant factors.

ATTACHMENT 3

Chapter 9
Demand Management Measures

N-C-424-60-26-28-WP-R-25-UWMP
9-11 City of Napa
2025 Urban Water Management Plan
May 2026

9.3.1 Urban Water Use Objectives
The Making Conservation a California Way of Life Legislation (Legislation) established a new framework for improvements in long-term urban water use efficiency. This Legislation builds on the statewide 2020 water conservation targets set under SB X7-7 (CWC §10609.2(d)). Under the Legislation, the State Water Board, in coordination with DWR, was required to adopt urban water use efficiency standards, variances, and performance measures by June 30, 2022.

On July 3, 2024, the State Water Board adopted the Making Conservation a California Way of Life Regulation. As part of this regulation, urban water suppliers will be held to annual UWUOs. The City is required to calculate its UWUO annually, which is a sum of water efficiency budgets for the following uses:
• Residential indoor water use,
• Residential outdoor water use,
• Real water loss, and
• CII landscapes with dedicated irrigation meters (DIMs).

The City’s UWUO is calculated using statewide efficiency standards, and considers the City’s water service area population, climate, and landscape area. Efficiency standards for the different components will progressively decrease from 2025 to 2040. Varian ces and adjustments may be allowed for special cases such as seasonal population fluctuation, special landscape areas (sports fields and recreational areas), direct/indirect potable reuse, and agricultural uses. Figure 9-1 summarizes the components that make up the UWUO.

Figure 9-1. Urban Water Use Objective Components1
In addition to calculating and complying with the UWUO, beginning in 2027, the City will need to classify its CII properties, and begin deploying best management practices (BMPs) for indoor and outdoor CII water use. These CII performance measures are intended to enable water -usage benchmarking per CII classification category, as well as establish BMPs for indoor and outdoor CII water use.

1California Water Efficiency Partnership. May 2024. Making Conservation a California Way of Life Standards Framework Cut Sheet.

ATTACHMENT 3

Chapter 9
Demand Management Measures

N-C-424-60-26-28-WP-R-25-UWMP
9-12 City of Napa
2025 Urban Water Management Plan
May 2026

9.3.1.1 Annual Water Use Reporting
Starting in 2024, the City is required to calculate its UWUO, compare its actual water use to its UWUO, and provide an Annual Water Use Report to the State by January 1 of each year. Reporting is based on fiscal year data. The City’s UWUO will become increasingly stringent from 2025 to 2040. If the City anticipates that it would not be able to meet this regulation , the City will need to develop a plan and intensify or implement demand management actions to maintain compliance with the regulation.

The City submitted its Fiscal Year 2024/25 Annual Water Use Report to the State in December 2025. The report indicated that the City’s water use is well below its UWUO and that the City will likely continue to meet its UWUO over at least the next several years. The City will continue to prepare its Annual Water Use Report each year to assess progress.

Reporting and compliance with the UWUO falls under the authority of the State Water Board and is tracked separately from the UWMP. Therefore, UWUO compliance projections are not included in this UWMP.

ATTACHMENT 3

N-C-424-60-26-28-WP-R-25-UWMP
10-1 City of Napa
2025 Urban Water Management Plan
May 2026

CHAPTER 10
Plan Adoption, Submittal, and Implementation
This chapter provides information regarding the notification, public hearing, adoption, and submittal of the City’s 2025 UWMP and WSCP. It also includes discussion on plan implementation and the process of amending the UWMP and WSCP.

10.1 INCLUSION OF ALL 2025 DATA
As indicated in Section 2.4 of this plan, the City uses a calendar year for water supply and demand accounting, and therefore this plan includes data through December 2025.

10.2 NOTICE OF PUBLIC HEARING
In accordance with the Act, the City must provide an opportunity for the public to provide input on this plan, including the WSCP . The City must consider all public input prior to its adoption. There are two audiences to be notified for the public hearing: cities/counties and the public.

10.2.1 Notices to Cities and Counties
As discussed in Section 2.5 of this plan, the City provided greater than a 60 -day notice regarding the preparation of its 202 5 UWMP and WSCP to cities and counties in its service area including the following agencies:
• City of American Canyon
• Town of Yountville
• City of St. Helena
• City of Calistoga
• Napa Sanitation District
• Veterans Home of California
• Napa County
The notices of preparation are included as Appendix E. Notifications to cities and counties in accordance with the Act are summarized in Table 10-1.

The City also coordinated the preparation of this plan internally and with input from the above-listed agencies. Upon substantial completion of this plan, the City provided the agencies listed above, including internally within the City and the County, notices of public hearing (Appendix E).

ATTACHMENT 3

Chapter 10
Plan Adoption, Submittal, and Implementation

N-C-424-60-26-28-WP-R-25-UWMP
10-2 City of Napa
2025 Urban Water Management Plan
May 2026

Table 10-1. Notification to Cities and Counties
(DWR Table 10-1 Retail)

10.2.2 Notice to the Public
To allow ample time for public comments to be prepared and received, the City issued a notice of public hearing to the public and provided a public review period following the notice and prior to adoption of the 2025 UWMP and WSCP.

A notice of public hearing was issued in accordance with Government Code Section 6066 and was published in The Press Democrat and Napa Valley Register newspapers. In addition, the notice was posted on the City’s website (cityofnapa.org/water). A copy of the published Notice of Public Hearing is included in Appendix E.

10.3 PUBLIC HEARING AND ADOPTION
The City encouraged community review of this plan, including its WSCP component, using newspaper notices, the City’s weekly e -newsletter, social media posts, and the City’s website. The public notices included the time and place of the public hearing, as well as the location where the plan is available for public inspection.

City Name 60 Day Notice
Drop Down (yes/no)
Notice of
Public Hearing
Drop Down (yes/no)
City of Napa Yes Yes
City of American Canyon Yes Yes
Town of Yountville Yes Yes
City of St. Helena Yes Yes
City of Calistoga Yes Yes
County Name
Drop Down List
60 Day Notice
Drop Down (yes/no)
Notice of Public Hearing
Drop Down (yes/no)
Napa County Yes Yes
NOTES: For Napa County, the Planning and Public Works Departments were each notified. In addition, the Napa Sanitation District (NapaSan) was notified, as it is the local recycled water purveyor. The Veterans Home of California was also notified, as it occasionally receives water deliveries from the City.

ATTACHMENT 3

Chapter 10
Plan Adoption, Submittal, and Implementation

N-C-424-60-26-28-WP-R-25-UWMP
10-3 City of Napa
2025 Urban Water Management Plan
May 2026

10.3.1 Public Hearing
The City held a public hearing on June 16, 2026, during which the City received and considered input from the public before adopting the 2025 UWMP and WSCP. As part of the public hearing, the City also provided a report on the City’s compliance with the Water Conservation Act of 2009. The report included information on the City’s baseline water use, water use targets, compliance, WSCP, and implementation of the UWMP.

The public hearing provided an opportunity for City water users and the general public to become familiar with the 2025 UWMP and WSCP and ask questions about the City’s plans for continuing to provide reliable, high-quality, essential drinking water supply and mitigating potential water shortage conditions.

Copies of the Draft 2025 UWMP were made available for public inspection at the Utilities Department, City Hall, and the Napa County Library. An electronic copy of the Draft 2025 UWMP was also available for review on the City’s website: cityofnapa.org/water. The public was invited to forward any written comments to the City Clerk.

10.3.2 Adoption
After the public hearing, this 202 5 UWMP and WSCP were adopted by the City Council on June 16, 2026. The City adopted the WSCP separately so that it may be updated independently of the UWMP as necessary. Copies of the adopted resolutions are included in Appendix K.

10.4 PLAN SUBMITTAL
This adopted 2025 UWMP will be submitted to DWR within 30 days of adoption and by July 1, 2026 .

The adopted 2025 UWMP will be submitted electronically to DWR using the Water Use Efficiency (WUE) data submittal tool. A CD or hardcopy of the adopted 202 5 UWMP will also be submitted to the California State Library.

No later than 30 days after adoption, a copy of the adopted 202 5 UWMP, including the WSCP, will be provided to the cities and counties to which the City provides water.

10.5 PUBLIC AVAILABILITY
No later than 30 days after submittal to DWR, copies of this plan, including the adopted WSCP, will be available at the Utilities Department, City Hall, and the Napa County Library for public review during normal business hours. An electronic copy of the adopted 202 5 UWMP will also be available for review and download on the City’s website: cityofnapa.org/water.

10.6 PLAN IMPLEMENTATION
The 2025 UWMP will be the source document for any SB 610 Water Supply Assessments or SB 221 Water Supply Verifications required for any proposed projects in the City’s water service area between 2026 and 2030 that are subject to the California Environmental Quality Act and would demand an amount of water equivalent to or greater than the amount of water required by a 500-dwelling unit project. Also, this 2025 UWMP will provide guidance and direction on development of new local supplies and implementation of water use efficiency and conservation programs.

ATTACHMENT 3

Chapter 10
Plan Adoption, Submittal, and Implementation

N-C-424-60-26-28-WP-R-25-UWMP
10-4 City of Napa
2025 Urban Water Management Plan
May 2026

10.7 AMENDING AN ADOPTED UWMP OR WATER SHORTAGE CONTINGENCY PLAN
The City may amend its 202 5 UWMP and WSCP jointly or separately. If the City amends one or both documents, the City will follow the notification, public hearing, adoption, and submittal process described in Sections 10.2 through 10.4 above. In addition to submitting amendments to DW R through the WUE data portal, within 30 days after adoption, copies of amendments or changes to the plans will be submitted to the California State Library, as well as any city or county within which the supplier provides water.

ATTACHMENT 3

Urban Water Management Planning Act
Legislative Requirements

Appendix A
ATTACHMENT 3

Informational Purposes Only
January 2026 A-1
Appendix A
California Water Code—Urban Water
Management Planning
This material is for informational purposes only and is not to be used in place of official California Water Code.

This appendix presents updated sections of California Water Code (Water Code) as of the publication of this Guidebook and as compiled by California Department of Water Resources (DWR) staff. The selection here focuses on the portions of Water Code directly relevant to preparation of an Urban Water Management Plan (UWMP), and sections of Water Code that are contextually relevant to urban water suppliers and DWR.

Water Code published here also concerns the Urban Water Management Planning Act, the Water Conservation Act of 2009 (SB X7-7), which covers sustainable water use and demand reduction, and more. Further legislative information is available on the California Legislative Information website.

Contents
Water Conservation Act of 2009 (SB X7‐7) ................................................. A-3 Chapter 1. General Declarations and Policy, Sections 10608– 10608.8 .................................................................................. A-3 Chapter 2. Definitions, Section 10608.12 ............................................. A-5 Chapter 2.5. Nonfunctional Turf .......................................................... A-9 Chapter 3. Urban Retail Water Suppliers, Sections 10608.16– 10608.44 ............................................................................... A-11 Chapter 5. Sustainable Water Management, Section 10608.50 .............. A-21 Chapter 6. Standardized Data Collection, Section 10608.52 .................. A-22 Chapter 7. Funding Provisions, Sections 10608.56–10608.60 .................. A-23 Chapter 9. Urban Water Use Objectives and Water Use Reporting, Sections 10609–10609.38 ........................................................ A-24 Urban Water Management Planning Act .................................................... A-39 Chapter 1. General Declaration and Policy, Sections 10610– 10610.4 ................................................................................. A-39 Chapter 2. Definitions, Sections 10611–10618 ..................................... A-40 Chapter 3. Urban Water Management Plans ........................................ A-42 Article 1. General Provisions, Sections 10620–10621 ................... A-42 Article 2. Contents of Plans, Sections 10630–10634 ..................... A-44 ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-2
Article 2.5. Water Service Reliability, Section 10635 .................... A-54 Article 3. Adoption and Implementation of Plans,
Sections 10640–10645 ................................................. A-55 Chapter 4. Miscellaneous Provisions, Sections 10650–10657 ................. A-58

ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-3
Water Conservation Act of 2009 (SB X7‐7)
This section contains information extracted from Water Code Division 6, Conservation, Development, and Utilization of State Water Resources, Part 2.55, Sustainable Water Use And Demand Reduction. Click on any section header below to read Water Code directly at the California Legislative Information website.

Chapter 1. General Declarations and Policy,
Sections 10608–10608.8
Section 10608.

The Legislature finds and declares all of the following:
(a) Water is a public resource that the California Constitution protects against waste and unreasonable use.
(b) Growing population, climate change, and the need to protect and grow California’s economy while protecting and restoring our fish and wildlife habitats make it essential that the state manage its water resources as efficiently as possible.
(c) Diverse regional water supply portfolios will increase water supply reliability and reduce dependence on the Delta.
(d) Reduced water use through conservation provides significant energy and environmental benefits, and can help protect water quality, improve streamflows, and reduce greenhouse gas emissions.
(e) The success of state and local water conservation programs to increase efficiency of water use is best determined on the basis of measurable outcomes related to water use or efficiency.
(f) Improvements in technology and management practices offer the potential for increasing water efficiency in California over time, providing an essential water management tool to meet the need for water for urban, agricultural, and environmental uses.
(g) The Governor has called for a 20 percent per capita reduction in urban water use statewide by 2020.
(h) The factors used to formulate water use efficiency targets can vary significantly from location to location based on factors including weather, patterns of urban and suburban development, and past efforts to enhance water use efficiency.
(i) Per capita water use is a valid measure of a water provider’s efforts to reduce urban water use within its service area. However, per capita water use is less ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-4
useful for measuring relative water use efficiency between different water providers. Differences in weather, historical patterns of urban and suburban development, and density of housing in a particular location need to be considered when assessing per capita water use as a measure of efficiency.

Section 10608.4.

It is the intent of the Legislature, by the enactment of this part, to do all of the following:
(a) Require all water suppliers to increase the efficiency of use of this essential resource.
(b) Establish a framework to meet the state targets for urban water conservation identified in this part and called for by the Governor. (c) Measure increased efficiency of urban water use on a per capita basis. (d) Establish a method or methods for urban retail water suppliers to determine targets for achieving increased water use efficiency by the year 2020, in accordance with the Governor’s goal of a 20- percent reduction. (e) Establish consistent water use efficiency planning and implementation standards for urban water suppliers and agricultural water suppliers. (f) Promote urban water conservation standards that are consistent with the California Urban Water Conservation Council’s adopted best management practices and the requirements for demand management in Section 10631. (g) Establish standards that recognize and provide credit to water suppliers that made substantial capital investments in urban water conservation since the drought of the early 1990s.
(h) Recognize and account for the investment of urban retail water suppliers in providing recycled water for beneficial uses.
(i) Require implementation of specified efficient water management practices for agricultural water suppliers.
(k) Support the economic productivity of California’s agricultural, commercial, and industrial sectors.
(l) Advance regional water resources management.

Section 10608.8.
(a)
(1) Water use efficiency measures adopted and implemented pursuant to this part or Part 2.8 (commencing with Section 10800) are water conservation measures subject to the protections provided under Section 1011.

ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-5
(2) Because an urban agency is not required to meet its urban water use target until 2020 pursuant to subdivision (b) of Section 10608.24, an urban retail water supplier’s failure to meet those targets shall not establish a violation of law for purposes of any state administrative or judicial proceeding prior to January 1, 2021. Nothing in this paragraph limits the use of data reported to the department or the board in litigation or an administrative proceeding. This paragraph shall become inoperative on January 1, 2021.
(3) To the extent feasible, the department and the board shall provide for the use of water conservation reports required under this part to meet the requirements of Section 1011 for water conservation reporting. (b) This part does not limit or otherwise affect the application of Chapter 3.5 commencing with Section 11340), Chapter 4 (commencing with Section 11370), Chapter 4.5 (commencing with Section 11400), and Chapter 5 (commencing with Section 11500) of Part 1 of Division 3 of Title 2 of the Government Code.
(c) This part does not require a reduction in the total water used in the agricultural or urban sectors, because other factors, including, but not limited to, changes in agricultural economics or population growth may have greater effects on water use. This part does not limit the economic productivity of California’s agricultural, commercial, or industrial sectors.
(d) The requirements of this part do not apply to an agricultural water supplier that is a party to the Quantification Settlement Agreement, as defined in subdivision (a) of Section 1 of Chapter 617 of the Statutes of 2002, during the period within which the Quantification Settlement Agreement remains in effect.

After the expiration of the Quantification Settlement Agreement, to the extent conservation water projects implemented as part of the Quantification Settlement Agreement remain in effect, the conserved water created as part of those projects shall be credited against the obligations of the agricultural water supplier pursuant to this part.

Chapter 2. Definitions, Section 10608.12
Section 10608.12.

Unless the context otherwise requires, the following definitions govern the construction of this part:
(a) “Affordable housing” has the same meaning as defined in Section 34191.30 of the Health and Safety Code.
(b) “Agricultural water supplier” means a water supplier, either publicly or privately owned, providing water to 10,000 or more irrigated acres, excluding recycled water. “Agricultural water supplier” includes a supplier or contractor ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-6
for water, regardless of the basis of right, that distributes or sells water for ultimate resale to customers. “Agricultural water supplier” does not include the department.
(c) “Base daily per capita water use” means any of the following:
(1) The urban retail water supplier’s estimate of its average gross water use, reported in gallons per capita per day and calculated over a continuous 10-year period ending no earlier than December 31, 2004, and no later than December 31, 2010.
(2) For an urban retail water supplier that meets at least 10 percent of its 2008 measured retail water demand through recycled water that is delivered within the service area of an urban retail water supplier or its urban wholesale water supplier, the urban retail water supplier may extend the
(3) calculation described in paragraph (1) up to an additional five years to a maximum of a continuous 15-year period ending no earlier than December 31, 2004, and no later than December 31, 2010. (4) For the purposes of Section 10608.22, the urban retail water supplier’s estimate of its average gross water use, reported in gallons per capita per day and calculated over a continuous five-year period ending no earlier than December 31, 2007, and no later than December 31, 2010. (d) Baseline commercial, industrial, and institutional water use” means an urban retail water supplier’s base daily per capita water use for commercial, industrial, and institutional users.
(e) “CII water use” means water used by commercial water users, industrial water users, institutional water users, and large landscape water users. (f) “Commercial water user” means a water user that provides or distributes a product or service.
(g) “Common area” means that portion of a common interest development or of a property owned or managed by a homeowners’ association or a community service organization or similar entity that is not assigned or allocated to the exclusive use of the occupants of an individual dwelling unit within the property.
(h) “Common interest development” has the same meaning as in Section 4100 of the Civil Code.
(i) “Community service organization or similar entity” has the same meaning as in Section 4110 of the Civil Code.
(j) “Community space” means an area designated by a property owner or a governmental agency to accommodate human foot traffic for civic, ceremonial, or other community events or social gatherings
ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-7
(k) Compliance daily per capita water use” means the gross water use during the final year of the reporting period, reported in gallons per capita per day. (l) “Disadvantaged community” means a community with an annual median household income that is less than 80 percent of the statewide annual median household income.
(m) “Functional turf” means a ground cover surface of turf located in a recreational use area or community space. Turf enclosed by fencing or other barriers to permanently preclude human access for recreation or assembly is not functional turf.
(n) “Gross water use” means the total volume of water, whether treated or untreated, entering the distribution system of an urban retail water supplier, excluding all of the following:
(1) Recycled water that is delivered within the service area of an urban retail water supplier or its urban wholesale water supplier.
(2) The net volume of water that the urban retail water supplier places into long-term storage.
(3) The volume of water the urban retail water supplier conveys for use by another urban water supplier.
(4) The volume of water delivered for agricultural use, except as otherwise provided in subdivision (f) of Section 10608.24.
(o) “Homeowners’ association” means an “association” as defined in Section 4080 of the Civil Code.
(p) “Industrial water user” means a water user that is primarily a manufacturer or processor of materials as defined by the North American Industry Classification System code sectors 31 to 33, inclusive, or an entity that is a water user primarily engaged in research and development.
(q) “Institutional water user” means a water user dedicated to public service. This type of user includes, among other users, higher education institutions, schools, courts, churches, hospitals, government facilities, and nonprofit research institutions.
(r) “Interim urban water use target” means the midpoint between the urban retail water supplier’s base daily per capita water use and the urban retail water supplier’s urban water use target for 2020.
(s) “Large landscape” means a nonresidential landscape as described in the performance measures for CII water use adopted pursuant to Section 10609.10.
(t) “Locally cost effective” means that the present value of the local benefits of implementing an agricultural efficiency water management practice is greater ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-8
than or equal to the present value of the local cost of implementing that measure.
(u) “Nonfunctional turf” means any turf that is not functional turf, and includes turf located within street rights-of-way and parking lots. (v) “Performance measures” means actions to be taken by urban retail water suppliers that will result in increased water use efficiency by CII water users.

Performance measures may include, but are not limited to, educating CII water users on best management practices, conducting water use audits, and preparing water management plans. Performance measures do not include process water.
(w) “Potable reuse” means direct potable reuse, indirect potable reuse for groundwater recharge, and reservoir water augmentation as those terms are defined in Section 13561.
(x) “Potable water” means water that is suitable for human consumption. (y) “Process water” means water used by industrial water users for producing a product or product content or water used for research and development.

Process water includes, but is not limited to, continuous manufacturing processes, and water used for testing, cleaning, and maintaining equipment.

Water used to cool machinery or buildings used in the manufacturing process or necessary to maintain product quality or chemical characteristics for product manufacturing or control rooms, data centers, laboratories, clean rooms, and other industrial facility units that are integral to the manufacturing or research and development process is process water. Water used in the manufacturing process that is necessary for complying with local, state, and federal health and safety laws, and is not incidental water, is process water. Process water does not mean incidental water uses.
(z) “Public water system” has the same meaning as defined in Section 116275 of the Health and Safety Code.
(aa) “Recreational use area” means an area designated by a property owner or a governmental agency to accommodate human foot traffic for recreation, including, but not limited to, sports fields, golf courses, playgrounds, picnic grounds, or pet exercise areas. This recreation may be either formal or informal.
(ab) “Recycled water” means recycled water, as defined in subdivision (n) of Section 13050.
(ac) “Regional water resources management” means sources of supply resulting from watershed-based planning for sustainable local water reliability or any of the following alternative sources of water:
(1) The capture and reuse of stormwater or rainwater.
(2) The use of recycled water.

ATTACHMENT 3

Appendix A
California Water Code—Urban Water Management Planning
Informational Purposes Only
January 2026 A-9
(3) The desalination of brackish groundwater.
(4) The conjunctive use of surface water and groundwater in a manner that is consistent with the safe yield of the groundwater basin. (ad) “Reporting period” means the years for which an urban retail water supplier reports compliance with the urban water use targets.
(ae) “Turf” has the same meaning as defined in Section 491 of Title 23 of the California Code of Regulations
(af) “Urban retail water supplier” means a water supplier, either publicly or privately owned, that directly provides potable municipal water to more than 3,000 end users or that supplies more than 3,000 acre-feet of potable water annually at retail for municipal purposes.
(ag) “Urban water supplier” has the same meaning as defined in Section 10617. (ah) “Urban water use objective” means an estimate of aggregate efficient water use for the previous year based on adopted water use efficiency standards and local service area characteristics for that year, as described in Section 10609.20.
(ai) “Urban water use target” means the urban retail water supplier’s targeted future daily per capita water use.
(aj) “Urban wholesale water supplier” means a water supplier, either publicly or privately owned, that provides more than 3,000 acre- feet of water annually at wholesale for potable municipal purposes.

Chapter 2.5. Nonfunctional Turf
Section 10608.14.
(a) The use of potable water for the irrigation of nonfunctional turf located on commercial, industrial, and institutional properties, other than a cemetery, and on properties of homeowners’ associations, common interest developments, and community service organizations or similar entities is prohibited as of the following dates:
(1) All properties owned by the Department of General Services, beginning January 1, 2027.
(2) All properties owned by local governments, local or regional public agencies, and public water systems, except those specified in paragraph (5), beginning January 1, 2027.
(3) All other institutional properties and all commercial and industrial properties, beginning January 1, 2028.

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Appendix A
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Informational Purposes Only
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(4) All common areas of properties of homeowners’ associations, common interest developments, and community service organizations or similar entities, beginning January 1, 2029.
(5) All properties owned by local governments, local public agencies, and public water systems in a disadvantaged community, beginning January 1, 2031, or the date upon which a state funding source is made available to fund conversion of nonfunctional turf on these properties to climate- appropriate landscapes, whichever is later.
(b) Notwithstanding subdivision (a), the use of potable water is not prohibited by this section to the extent necessary to ensure the health of trees and other perennial nonturf plantings, or to the extent necessary to address an immediate health and safety need.
(c) The board may, upon a showing of good cause for reasons including economic hardship, critical business need, and potential impacts to human health or safety, postpone a compliance deadline in subdivision (a) by up to three years for certain persons, institutions, and businesses, and may create a form to be used for compliance certification to the board by property owners. (d) Public water systems shall, by no later than January 1, 2027, revise their regulations, ordinances, or policies governing water service to include the requirements of subdivisions (a) and (b), as revised by the board pursuant to subdivision (c), and shall communicate the requirements to their customers on or before that date.
(e)
(1) An owner of commercial, industrial, or institutional property with more than 5,000 square feet of irrigated area other than a cemetery shall certify to the board, commencing June 30, 2030, and every three years thereafter through 2039, that their property is in compliance with the requirements of this chapter.
(2) An owner of a property with more than 5,000 square feet of irrigated common area that is a homeowners’ association, common interest development, or community service organization or similar entity shall certify to the board, commencing June 30, 2031, and every three years thereafter through 2040, that their property is in compliance with the requirements of this chapter.
(f) Noncompliance by a person or entity with this chapter or regulations adopted thereunder shall be subject to civil liability and penalties set forth in Section 1846, or to civil liability and penalties imposed by an urban retail water supplier pursuant to a locally adopted ordinance or policy.

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(g)
(1) A public water system, city, county, or city and county may enforce the provisions of this chapter.
(2) To avoid duplication of enforcement, any entity identified in paragraph (1) that is not a retail public water system shall notify the retail public water system 30 days prior to enforcement of the provisions of this chapter against a property served by such system.
(3) Nothing in paragraph (2) shall preclude enforcement by any entity identified in paragraph (1) once adequate notice is given. (h) The department shall, when using funds appropriated for water conservation for turf replacement, prioritize financial assistance for nonfunctional turf replacement to public water systems serving disadvantaged communities and to owners of affordable housing.
(i) The department shall utilize the saveourwater.com internet website and outreach campaign to provide information and resources on converting nonfunctional turf to native vegetation.
(j) The Governor’s Office of Business and Economic Development shall support small and minority-owned businesses that provide services that advance compliance with this chapter.

Chapter 3. Urban Retail Water Suppliers,
Sections 10608.16–10608.44
Section 10608.16.
(a) The state shall achieve a 20-percent reduction in urban per capita water use in California on or before December 31, 2020.
(1) The state shall make incremental progress towards the state target specified in subdivision (a) by reducing urban per capita water use by at least 10 percent on or before December 31, 2015.

Section 10608.20.
(a)
(1) Each urban retail water supplier shall develop urban water use targets and an interim urban water use target by July 1, 2011. Urban retail water suppliers may elect to determine and report progress toward achieving these targets on an individual or regional basis, as provided in subdivision (a) of Section 10608.28, and may determine the targets on a fiscal year or calendar year basis.

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Informational Purposes Only
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(2) It is the intent of the Legislature that the urban water use targets described in paragraph (1) cumulatively result in a 20-percent reduction from the baseline daily per capita water use by December 31, 2020. (b) An urban retail water supplier shall adopt one of the following methods for determining its urban water use target pursuant to subdivision (a):
(1) Eighty percent of the urban retail water supplier’s baseline per capita daily water use.
(2) The per capita daily water use that is estimated using the sum of the following performance standards:
(A) For indoor residential water use, 55 gallons per capita daily water use as a provisional standard. Upon completion of the department’s 2017 report to the Legislature pursuant to Section 10608.42, this standard may be adjusted by the Legislature by statute. (B) For landscape irrigated through dedicated or residential meters or connections, water efficiency equivalent to the standards of the Model Water Efficient Landscape Ordinance set forth in Chapter 2.7 (commencing with Section 490) of Division 2 of Title 23 of the California Code of Regulations, as in effect the later of the year of the landscape’s installation or 1992. An urban retail water supplier using the approach specified in this subparagraph shall use satellite imagery, site visits, or other best available technology to develop an accurate estimate of landscaped areas.
(C) For commercial, industrial, and institutional uses, a 10- percent reduction in water use from the baseline commercial, industrial, and institutional water use by 2020.
(3) Ninety-five percent of the applicable state hydrologic region target, as set forth in the state’s draft 20x2020 Water Conservation Plan (dated April 30, 2009). If the service area of an urban water supplier includes more than one hydrologic region, the supplier shall apportion its service area to each region based on population or area.
(4) A method that shall be identified and developed by the department, through a public process, and reported to the Legislature no later than December 31, 2010. The method developed by the department shall identify per capita targets that cumulatively result in a statewide 20- percent reduction in urban daily per capita water use by December 31, 2020. In developing urban daily per capita water use targets, the department shall do all of the following:
(A) Consider climatic differences within the state.
(B) Consider population density differences within the state. (C) Provide flexibility to communities and regions in meeting the targets.

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