City Council / Housing Authority
May 18, 2026

2025 Part 1: Regional Context

THREE VALLEYS

REGIONAL URBAN WATER

MANAGEMENT PLAN
APRIL 2026

PUBLIC REVIEW DRAFT

THREE VALLEYS REGIONAL

URBAN WATER MANAGEMENT PLAN
Regional Context2025 Part 1:

APRIL 2026
Prepared by GEI Consultants, Inc. and Water Systems Consulting, Inc.

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. i
Table of Contents
Standard Limitations and Disclaimer .................................................................... v Acronyms and Abbreviations ...................................................................................vi Executive Summary ..................................................................................................... ix E.S.1. Purpose of the Plan ix
E.S.2. Agencies Included in the RUWMP ix
E.S.3. Regional Setting x
E.S.4. Population and Water Demand Projections x
E.S.5. Regional Water Supply Portfolio x
E.S.6. Water Supply Reliability and Drought Planning xi E.S.7. Threats to Local Supply Reliability xi
E.S.8. Planned Capital Projects xii
E.S.9. Water Conservation and Water Use Efficiency xii
E.S.10. Regional Coordination xiii
E.S.11. Conclusion xiii
E.S.12. Use of This Plan xiii

1. Introduction ......................................................................................................... 1

1.1. Background and Purpose 1

1.1.1. Regional Urban Water Management Plan 2

1.2. Plan Organization 2

1.3. Plan Preparation and Coordination 6

1.3.1. Participating Agencies 6

1.3.2. Public Participation 7

1.3.3. Stakeholder Workshops 10

1.4. Plan Adoption 10

2. Region Description ......................................................................................... 13

2.1. Regional Setting 13

2.2. Water Agencies in the Region 15

2.2.1. Water Supply Managers, Wholesalers, and Retailers 15

2.3. Population and Demographics 16

2.3.1. Historic Population Growth 16

2.3.2. Future Population Projections 18

2.3.3. Other Demographic Information 19

2.4. Land Uses 20

2.5. Regional Climate 23

2.5.1. Current Regional Climate 23
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. ii

2.5.2. Potential Effects of Climate Change 24

3. Regional Water Sources and Management ............................................. 26

3.1. Imported Water 27

3.1.1. Supply Description and Management 27

3.1.2. Supply Reliability and Climate Impacts 28

3.1.3. Imported Water Quality 30

3.1.4. Other Imported and Purchased Water Supplies 31

3.2. Groundwater 32

3.2.1. Main San Gabriel Basin 34

3.2.2. Chino Basin 37

3.2.3. Six Basins 40

3.2.4. Spadra Basin 43

3.2.5. Central Basin 45

3.2.6. Puente Basin 47

3.2.7. Groundwater Quality Impacts on Reliability 49

3.3. Surface Water 52

3.3.1. Surface Hydrology and Major Sources 53

3.3.2. Surface Water Diversions and Management 53

3.3.3. Surface Water Quality and Climate Impacts 54

3.4. Stormwater 56

3.4.1. Regional Stormwater Capture Facilities 56

3.4.2. Climate Change Vulnerabilities and Planned Improvements 57

3.5. Recycled Water and Wastewater 58

3.5.1. Wastewater Collection and Treatment 58

3.5.2. Current Recycled Water Uses 59

3.5.3. Planned Recycled Water Projects 60

3.6. Transfers and Exchanges 60

3.7. Supply From Storage 61

3.7.1. TVMWD Regional Storage Capacity and MWD Cyclic Storage 61

3.7.2. Recharge Mechanisms and Operational Constraints 64

3.8. Desalination Opportunities 64

3.8.1. Opportunities for Brackish Water and/or Groundwater Desalination 64

3.8.2. Opportunities for Seawater Desalination 65

3.9. Planned Water Supply Projects and Programs 65

4. Regional Water Use ........................................................................................ 68

4.1. Total Water Demands by Agency 68

4.2. Water Use Efficiency 69

4.2.1. SB X7-7 Compliance 69

4.2.2. New Water Conservation Legislation 69

4.2.3. Regional Demand Management Programs 70
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. iii

5. Comparison of Regional Supplies and Demands .................................. 72

5.1. Supply and Demand Projections Methodology 72

5.1.1. Demand Projections 72

5.1.2. Supply Projections 73

5.2. Summary of Regional Supplies and Demands 74

5.2.1. Normal Year 74

5.2.2. Single Dry Year 77

5.2.3. Five-Consecutive Dry Year and Drought Risk (2026-2030) Assessments 78

6. References ......................................................................................................... 82 Tables
Table 1-1. Regional vs. Individual Reporting Matrix 6
Table 1-2. Stakeholders Notified of the Preparation of the 2025 RUWMP (60‑Day Notice) 8 Table 1-3. Participating Agency RUWMP Adoption Dates and Resolutions 11 Table 2-1. Water Management Agencies in the TVMWD Region 16 Table 2-2. Los Angeles County Population, 1980 to 2020 17 Table 2-3. TVMWD Population, 1990 to 2020 17
Table 2-4. Los Angeles County Projected Population, 2025 to 2050 18 Table 2-5. Projected Population for the Region (2030 to 2050) 19 Table 2-6. Projected Household for the TVMWD Service Area (2019 to 2050) 19 Table 2-7. Projected Employment for the TVMWD Service Area (2019 to 2050) 19 Table 2-8. Approximate Regional Land Use Distribution 23 Table 2-9. Regional Climate Characteristics (Jul 1990 – Sep 2025) 24 Table 3-1. Overview of Water Sources Used by TVMWD Member Agencies 27 Table 3-2. Projected Availability of TVMWD Wholesale Imported Supplies (from MWD) 29 Table 3-3. Historical Groundwater Production from the Main San Gabriel Basin by TVMWD Agencies (AFY) 35
Table 3-4. Historical and Projected Operating Safe Yield of the Main San Gabriel Basin 35 Table 3-5. TVMWD Storage and Export Agreements in the Main San Gabriel Basin 37 Table 3-6. Historical Groundwater Production from the Chino Basin by TVMWD Agencies (AFY) 40 Table 3-7. TVMWD Storage Agreements in the Chino Basin 40 Table 3-8. Historical Groundwater Production from the Six Basins by TVMWD Agencies (AFY) 41 Table 3-9. Recent Operating Safe Yields (Four Basins) 42 Table 3-10. TVMWD Storage Agreements in the Six Basins 43 Table 3-11. Historical Groundwater Production from the Spadra Basin by TVMWD Agencies (AFY) 44 Table 3-12. Historical Groundwater Production from the Central Basin by TVMWD Agencies (AFY) 47 Table 3-13. Primary Groundwater Contaminants and Regional Treatment Strategies 50 Table 3-14. Primary Surface Water Quality Challenges and Operational Impacts 55 Table 3-15. Major Stormwater Capture and Spreading Facilities Benefiting the Region 57 Table 3-16. Wastewater Treatment Plants Serving the Region 59 Table 3-17. Historical Annual Recycled Water Use by TVMWD Agencies (2021-2025) 60 Table 3-18. TVMWD Regional Groundwater Storage Portfolio Summary 63 Table 4-1. Projected Total Water Demand (RUWMP Participating Agencies) (Acre-Feet) 68 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. iv
Table 5-1. Normal Year Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) 76 Table 5-2. Normal Year Supply and Demand (Regional Total – All Agencies) (Acre-Feet) 77 Table 5-3. Single Dry Year Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) 78 Table 5-4. Single Dry Year Supply and Demand (Regional Total – All Agencies) (Acre-Feet) 78 Table 5-5. Regional Drought Risk Assessment (2026-2030) Supply and Demand by Source (RUWMP Participating Agencies) (Acre-Feet) 79
Table 5-6. Regional Drought Risk Assessment (2026-2030) Supply and Demand by Source (Regional Total – All Agencies) (Acre-Feet) 80
Table 5-7. Multiple Dry Years Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) 80 Table 5-8. Multiple Dry Years Supply and Demand (Regional Total - All Agencies) (Acre-Feet) 81

Figures
Figure 1-1. Regional Context vs. Local Agency UWMPs Relationship 5 Figure 2-1. Map of TVMWD Service Area 14
Figure 2-2. Los Angeles County Population, 1980 to 2020 17 Figure 2-3. Connect SoCal RTP Population Projection Comparison 19 Figure 2-4. Regional Land Use Map 22
Figure 3-1. TVMWD Regional Groundwater Basins 33
Figure 4-1. Urban Water Use Objectives Regulation Overview 69

Appendices
Part 3 of the 2025 RUMWP contains Regional Supporting Information.

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. v
Standard Limitations and Disclaimer
This report was prepared exclusively for the use of Three Valleys Municipal Water District. The findings and conclusions, if any provided by GEI in this report, are based solely on the information reported to GEI as of the date of this report. Future investigations or additional information not provided to GEI at the time of this report may result in modification of this report. GEI’s scope of work did not include verifying the completeness or accuracy of information provided by others. Accordingly, GEI shall not be liable for any damages, costs, or other consequences resulting from reliance on such information if it is later determined to be inaccurate or incomplete. GEI’s professional services for this project have been performed in a manner consistent with that degree of skill and care ordinarily exercised by members of the same profession currently practicing in the same locality, performing similar services under similar conditions. GEI makes no other representations and no warranties, express or implied. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. vi
Acronyms and Abbreviations
Acronym Definition
AB1668 Assembly Bill 1668
AF Acre‑feet
AFY acre‑feet per year
APA Allowed Pumping Allocation
AWUR Annual Water Use Report
AWWA American Water Works Association
BPOU Baldwin Park Operable Unit
CEC Contaminants of Emerging Concern
cfs cubic feet per second
CIC Covina Irrigating Company
CIMIS California Irrigation Management Information System CRA Colorado River Aqueduct
CVWC Covina Valley Water Company
CWC California Water Code
DAC disadvantaged community
DDW Division of Drinking Water
DBP Disinfection Byproduct
DCP Drought Contingency Plan
DCR Delivery Capability Report
DMM demand management measure
DRA Drought Risk Assessment
DVL Diamond Valley Lake
DWR California Department of Water Resources
DYYP Dry‑Year Yield Program
ET evapotranspiration
ETo reference evapotranspiration
FY Fiscal year
GAC Granular Activated Carbon
GAMA Groundwater Ambient Monitoring and Assessment Program GHG greenhouse gas
GIS geographic information systems
GMP Groundwater Management Plan
GPCD gallons per capita per day
gpmd gallons per mile of pipe per day
gpscd gallons per service connection per day
GSA Groundwater Sustainability Agency
GSP Groundwater Sustainability Plan
IEUA Inland Empire Utilities Agency
JWL Joint Water Line
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. vii
Acronym Definition
LACSD Los Angeles County Sanitation Districts
LACDPW Los Angeles County Department of Public Works
LDX Local Data Exchange
LRP Local Resources Program
MAF million acre‑feet
MCL Maximum Contaminant Level
MHI Median Household Income
MGD million gallons per day
mg/L milligrams per liter
MWD Metropolitan Water District of Southern California
MWTP Miramar Water Treatment Plant
NTU Nephelometric Turbidity Unit
OBMP Optimum Basin Management Program
OSY Operating Safe Yield
PBWA Puente Basin Water Agency
PCE Tetrachloroethene
PFAS Per‑ and polyfluoroalkyl substances
PVPA Pomona Valley Protective Association
RHNA Regional Housing Needs Assessment
RO reverse osmosis
RUWMP Regional Urban Water Management Plan
SB1157 Senate Bill 1157
SB606 Senate Bill 606
SCAG Southern California Association of Governments
SGMA Sustainable Groundwater Management Act
SJCWRP San Jose Creek Water Reclamation Plant
SWP State Water Project
SWRCB State Water Resources Control Board
TAZs traffic analysis zones
TCE Trichloroethene
TDS Total Dissolved Solids
TOC Total Organic Carbon
TCP 1,2,3‑Trichloropropane
TVMWD Three Valleys Municipal Water District
USACE United States Army Corps of Engineers
USGS United States Geological Survey
UWMP Urban Water Management Plan
UWMP Act Urban Water Management Planning Act
VHWC Valencia Heights Water Company
VIC Variable Infiltration Capacity
VOC Volatile Organic Compounds
WUEData Water Use Efficiency Data
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. viii
Acronym Definition
WRD Water Replenishment District of Southern California WRMP Water Resources Master Plan
WRP water reclamation plant
WSCP Water Shortage Contingency Plan

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. ix
Executive Summary
E.S.1. Purpose of the Plan
The 2025 Regional Urban Water Management Plan (RUWMP or Plan) provides a long-range assessment of water supply reliability for the Three Valleys Municipal Water District (TVMWD) service area and its participating retail agencies through the year 2050. The Plan is prepared in accordance with the California Urban Water Management Planning Act and the 2025 UWMP Guidebook issued by the California Department of Water Resources (DWR) (DWR, 2026a). To satisfy the requirements of California Water Code Section 10630.5, this Executive Summary also serves as the statutory "Lay Description" of the Region's water supply reliability. The analytical framework, assumptions, and findings described in this lay description apply to all participating urban water suppliers included in this RUWMP. Individual UWMPs prepared as part of this regional effort rely on this description to satisfy the lay description requirement of the Urban Water Management Planning Act.

This RUWMP serves two primary purposes:

1. To clearly demonstrate that the Region has adequate and reliable water supplies to meet existing and projected future demands under normal conditions and during droughts; and

2. To provide a coordinated regional planning framework that improves consistency, reduces duplication, and strengthens individual UWMPs prepared by participating retail agencies.

By planning together at a regional scale, the agencies are better positioned to manage shared imported water systems and groundwater basins, respond to climate change, and maintain reliable water service for residents, businesses, and institutions.

E.S.2. Agencies Included in the RUWMP
This RUWMP was led by TVMWD in collaboration with seven retail water agencies (collectively referred to as the Participating Agencies):
⚫ City of Glendora
⚫ City of La Verne
⚫ City of Pomona
⚫ Golden State Water Company – Claremont System
⚫ Golden State Water Company – San Dimas System
⚫ Rowland Water District
⚫ Walnut Valley Water District
In addition, the regional analysis incorporates water demand and supply estimates for other water agencies operating within the TVMWD service area. These include the Boy Scouts of America - Firestone Reservation, California Polytechnic University Pomona (Cal Poly Pomona), the City of Covina, Mt. San 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. x
Antonio College (Mt. SAC), Suburban Water Systems, and Valencia Heights Water Company. While these agencies prepared their own independent UWMPs, their water use affects shared regional supplies.

Including them ensures that the regional water reliability analysis reflects total system conditions, rather than only participating agencies.

E.S.3. Regional Setting
The TVMWD service area (Region) covers approximately 133 square miles in southeastern Los Angeles County, extending from the foothills of the San Gabriel Mountains south to the Puente Hills and east toward the San Bernardino County line. The Region includes the Pomona Valley, Walnut Valley, and portions of the eastern San Gabriel Valley. The service area is predominantly urban with residential neighborhoods, commercial and industrial areas, educational institutions, and public facilities and is home to approximately 516,000 people as of the 2020 Census.

E.S.4. Population and Water Demand Projections
Population growth within the Region is expected to be modest through 2050, with most growth occurring through redevelopment and infill. Water demand projections account for anticipated population changes, employment trends, and land use patterns, as well as the effects of mandatory water conservation requirements.

Projected demands reflect ongoing and future reductions in per capita water use resulting from implementation of State mandated water use efficiency regulations, including the “Making Conservation a California Way of Life” requirements. These conservation measures are expected to partially offset demand increases associated with population growth and climate change.

E.S.5. Regional Water Supply Portfolio
The Region relies on a diversified water supply portfolio, which provides flexibility and resilience during dry conditions. Based on recent historical conditions (2021–2025), the regional water supply consists of:
⚫ Imported Water (~50%)
Water purchased from the Metropolitan Water District of Southern California (MWD), originating from the State Water Project (SWP) and the Colorado River, forms the backbone of the Region’s supply. MWD’s extensive surface and groundwater storage system provides a high level of drought reliability.
⚫ Local Groundwater (~44%)
Groundwater is produced from six basins: the Main San Gabriel Basin, Chino Basin, Six Basins, Spadra Basin, Central Basin, and Puente Basin. These basins are managed through court adjudications or Groundwater Sustainability Plans (GSPs) that protect long-term yields. ⚫ Recycled Water (~4%)
Several agencies use recycled water for non-potable purposes such as landscape irrigation, which reduces demand for potable supplies.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. xi
⚫ Local Surface Water (~2%)
Limited amounts of surface water are diverted from the San Gabriel River and San Antonio Creek, primarily during wet periods.

Together, these supplies support a robust conjunctive use strategy that includes storing imported water in local groundwater basins during wet years and withdrawing stored water during dry years.

E.S.6. Water Supply Reliability and Drought Planning
This RUWMP evaluates water supply reliability under multiple scenarios, including normal hydrologic conditions, a single dry year, and a five consecutive year drought. The analysis incorporates climate change considerations, including increased temperatures and changes in precipitation patterns.

The results of the reliability analysis demonstrate that sufficient supplies are projected to be available to meet regional water demands through 2050 under all evaluated scenarios. Short-term or localized reductions in groundwater or local surface water are assumed to be offset by imported water supplies from TVMWD and MWD, which are projected to remain fully reliable through the planning horizon.

Regional groundwater storage, access to imported water supplies, and coordinated drought response planning provide the necessary flexibility to manage extended dry periods.

Each Participating Agency maintains its own Water Shortage Contingency Plan (WSCP), which outlines actions to be taken during water shortages and drought conditions.

E.S.7. Threats to Local Supply Reliability
While the Region's water portfolio is highly reliable under modeled scenarios, TVMWD and the Participating Agencies face operational threats that require proactive management. These threats primarily impact the physical ability to access and utilize local water supplies:
⚫ Climate Volatility
As identified in the Region's 2024 Climate Change Vulnerability Assessment, rising temperatures and shifting hydrologic patterns threaten both supply and demand. The Region is projected to experience shorter, flashier rainy seasons characterized by high-intensity storm events. This volatility poses a direct challenge to local spreading grounds, as heavy storm flows can exceed the immediate capture capacity of diversion facilities, resulting in lost groundwater recharge.

Concurrently, hotter baseline temperatures are expected to drive up evapotranspiration and outdoor water demands.
⚫ Groundwater Quality and “Stranded Assets”
Decades of historical land-use practices have introduced contaminants – including Volatile Organic Compounds (VOCs), nitrates, and perchlorate – into the Region’s underlying aquifers.

Furthermore, the Region faces a threat from moving regulatory targets, specifically the introduction of ultra-low Maximum Contaminant Levels (MCLs) for Per- and Polyfluoroalkyl Substances (PFAS). When wells exceed these strict new safety standards, they must be taken offline. These "stranded assets" temporarily eliminate local extraction capacity, forcing agencies to rely more heavily on imported water when the Region is working to reduce that dependence. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. xii
E.S.8. Planned Capital Projects
To proactively mitigate these climate and regulatory vulnerabilities, TVMWD and its Participating Agencies have identified a suite of collaborative water supply projects. These regional partnerships focus on optimizing existing infrastructure, remediating stranded groundwater assets, expanding conjunctive use, and maximizing the capture of local supplies. Key planned regional projects include:
⚫ Restoring Stranded Assets (GRIP+)
A major regional partnership between TVMWD, the City of Glendora, and the City of Pomona to install new extraction wells and advanced wellhead treatment systems. By treating contaminated groundwater, this project will restore local extraction capacity and produce approximately 9,200 acre-feet per year (AFY) of highly reliable local supply from the Main San Gabriel Basin.
⚫ Advanced Recycled Water Storage (Spadra Basin Optimization) A collaborative initiative spearheaded by Walnut Valley Water District, the City of Pomona, and Cal Poly Pomona. This project proposes injecting advanced treated recycled water into the Spadra Basin via new injection wells, creating a drought-resilient local storage asset with a capacity of up to 3,500 acre-feet (AF).
⚫ Conjunctive Use Exchanges (Chino Basin)
Building upon existing successful dry-year yield programs, TVMWD and Pomona are evaluating an "in-lieu" exchange program. TVMWD would fund extraction and treatment upgrades in the Chino Basin in exchange for Pomona pumping and conveying an equivalent amount of local water to other TVMWD member agencies during droughts.
⚫ Stormwater Capture Enhancements
To address the shift toward shorter, higher-intensity winter storms, the Region is working with local flood control districts and protective associations to excavate deeper recharge basins (such as the San Antonio Spreading Grounds) and upgrade diversion structures. This will increase the instantaneous capture and storage volume of flash-flood runoff. ⚫ External Partnerships and Interties
The Region is actively pursuing new pipeline interties, such as a partnership through the Puente Basin Water Agency with the Covina Valley Water Company. This will allow the physical importation of up to 2,000 AFY of surplus local water eastward, directly offsetting reliance on imported water deliveries.

E.S.9. Water Conservation and Water Use Efficiency
Water conservation and water use efficiency are core components of the Region’s water management strategy. Retail agencies have implemented a wide range of conservation programs, including public education, rebate programs, landscape efficiency improvements, leak detection, and tiered water pricing.

All Participating Agencies previously met the State’s 2020 water conservation targets and continue to align with new efficiency standards established by State legislation and regulations. These efforts reduce long-term demand and improve overall system reliability. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. xiii
E.S.10. Regional Coordination
This RUWMP was developed through a coordinated regional planning process involving TVMWD and Participating Agencies. Regional planning allows for consistent assumptions regarding shared water supplies, reduces duplication of effort, and strengthens the technical foundation of individual agency UWMPs.

Public participation was incorporated through notices, public meetings, and hearings conducted by the Participating Agencies prior to adoption of the Plan. TVMWD also conducted regional workshops with the stakeholders in the Region to provide an update on the development of the RUWMP.

E.S.11. Conclusion
This RUWMP demonstrates that the TVMWD region has adequate and reliable water supplies to meet projected demands through 2050, even under extended drought conditions. Long-term water demands are expected to decline due to conservation regulations, despite modest population growth.

Through continued use of diversified water supplies, conservation, regional coordination, and proactive planning, the Region is well positioned to adapt to future challenges, including climate change and regulatory requirements, while maintaining reliable water service for residents and businesses.

Furthermore, continued investment in groundwater quality treatment is critical to protecting local water supplies. Regional coordination improves planning consistency and strengthens individual agency UWMPs.

E.S.12. Use of This Plan
This RUWMP serves as the regional technical foundation for each Participating Agency’s individual Urban Water Management Plan (UWMP). Each agency adopts the portions of the Plan relevant to its service area while maintaining authority over local operations, conservation programs, and water shortage response actions.

Taken together, the Regional Context (Part 1) and Individual Agency UWMP chapters (Part 2) along with the Regional Supporting Information (Part 3) and Agency Supporting Information (Part 4) provide a comprehensive, coordinated strategy to ensure safe, reliable, and sustainable water service for the Three Valleys region.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 1

1. Introduction
Three Valleys Municipal Water District (TVMWD) and its partnering agencies have long demonstrated a commitment to regional water resilience and sustainable resource management. As water supply reliability challenges continue to evolve across Southern California, TVMWD and its retail agencies recognize that water resources – specifically, imported water from the Metropolitan Water District of Southern California (MWD) and local groundwater basins – are regionally interdependent. To address these shared challenges and ensure consistent planning assumptions, TVMWD has led the development of this 2025 Regional Urban Water Management Plan (RUWMP or Plan) in collaboration with seven of its retail agencies.

The agencies participating in this 2025 RUWMP (Participating Agencies) include:
⚫ Three Valleys Municipal Water District (Lead Agency)
⚫ City of Glendora
⚫ City of La Verne
⚫ City of Pomona
⚫ Golden State Water Company (GSWC) (Claremont System)
⚫ GSWC (San Dimas System)
⚫ Rowland Water District (Rowland WD)
⚫ Walnut Valley Water District (WVWD)
In addition, there are two TVMWD retail agencies who have prepared independent 2025 UWMPs: the City of Covina and Suburban Water Systems. TVMWD has also coordinated with these agencies through development of this RUWMP and has incorporated their estimated supplies and demands into the regional analysis to provide a comprehensive analysis of regional water resources.

By coordinating as a Region1, the Participating Agencies aim to reduce redundancy, improve consistency in supply and demand assumptions, and strengthen the technical foundation for each agency’s individual planning efforts. This RUWMP presents a unified, regionally consistent analysis of water supply reliability, demand projections, and drought preparedness, providing a roadmap for the region to maintain reliable water service through 2050.

1.1. Background and Purpose
The California Water Code (CWC) requires urban water suppliers within the state to prepare and adopt Urban Water Management Plans (UWMPs) for submission to the California Department of Water Resources (DWR). The UWMPs, which are required to be filed every five years, must satisfy the requirements of the Urban Water Management Planning Act (UWMP Act) of 1983, including subsequent

1 The Three Valleys Municipal Water District service area is referred to as the Region in the context of this RUWMP. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 2

amendments. The UWMP Act requires urban water suppliers providing water for municipal purposes to more than 3,000 customers or supplying more than 3,000 acre-feet (AF) of water annually to prepare a UWMP.

A UWMP is intended to function as a long-term planning tool to guide broad-perspective decision- making by water suppliers. It is a general planning framework rather than an exact blueprint for supply and demand management. It generally answers a series of planning questions, including:

1. What are the potential sources of supply and what is the reasonable probable yield from them?

2. What is the probable demand, given a reasonable set of assumptions about growth and implementation of water use efficiency?

3. How well do supply and demand figures match up, assuming that the various probable supplies will be pursued?

4. How will the agency respond to drought conditions or water shortages? This 2025 RUWMP satisfies all CWC requirements for the 2025 cycle, including updates to the UWMP Guidebook, published by DWR in December 2025; details regarding these updates are described in Chapter 1 of the DWR 2025 UWMP Guidebook (DWR, 2026a).

1.1.1. Regional Urban Water Management Plan
Water purveyors are permitted by DWR to work together to develop a cooperative regional UWMP.

CWC Section 10620(d)(1) states: "An urban water supplier may satisfy the requirements of this part by participation in area wide, regional, watershed, or basin wide urban water management planning where those plans will reduce preparation costs and contribute to the achievement of conservation and efficient water use."
The purpose of jointly preparing this RUWMP is to facilitate a consistent evaluation of water sources common to the various agencies (specifically imported water from TVMWD and shared groundwater basins), to take advantage of group knowledge and experience, and to reduce preparation costs.

1.2. Plan Organization
This Plan is organized to meet the requirements of the UWMP Act for the eight Participating Agencies (TVMWD and seven retail agencies). Each Participating Agency has reviewed, adopted, and will implement the portions of this Plan relevant to their agency.

To streamline reporting and avoid redundant data entry, this Plan is organized into four distinct parts:

Part 1: Regional Context
Part 1 contains the information needed to meet the UWMP Act requirements that are common to all Participating Agencies. This section provides a comprehensive "roll-up" of the region’s water portfolio. It includes:
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 3

⚫ Regional System Description: A description of the climate, demographics, and land use for the entire TVMWD service area.
⚫ Water Sources: Detailed descriptions of the shared imported water supplies (from MWD) and the management of regional groundwater basins (Main San Gabriel, Chino, Six Basins, Spadra, Central, and Puente).
⚫ Regional Reliability: An aggregation of supply and demand projections to assess water reliability for normal, single-dry, and five-year consecutive drought scenarios through 2050. Also includes a near-term stress test assessing the region’s ability to meet demands during a drought over the next five years (2026–2030).

It should be noted that while the RUWMP is authored and adopted by the eight Participating Agencies listed above, the regional analysis in Part 1 incorporates data from Other Member Agencies within the TVMWD service area (such as the City of Covina and Suburban Water Systems) to ensure the regional supply and demand assessment accurately reflects the total water use within the TVMWD service area.

Part 2: Individual Agency UWMPs
Part 2 includes a specific chapter for each of the Participating Agencies. Each chapter is supplemental to the regional information presented in Part 1. These chapters contain the agency-specific data required to meet the UWMP Act that cannot be reported regionally, including:
⚫ Service area maps and climate characteristics.
⚫ Descriptions of past and current water use.
⚫ Future demand projection methodologies.
⚫ Local water distribution system losses (water loss audit results). ⚫ SB X7-7 and future water use objectives.
⚫ Water supply entitlements or constraints unique to that retailer. ⚫ Water Shortage Contingency Plan (WSCP) adoption and protocols. ⚫ Demand management measures implemented by that retailer. ⚫ RUWMP adoption.

Part 3: Regional Supporting Information
Part 3 includes all supporting documentation referenced in Part 1 that is applicable to the region as a whole. This includes the DWR Regional UWMP Checklist (Appendix A), documentation of regional public notices and workshops, water supply agreements and legal documents, and the regional adoption resolution by the Lead Agency (TVMWD), which formally adopts both this Regional Context and TVMWD’s specific wholesale UWMP components.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 4

Part 4: Local Agency Supporting Information
Part 4 includes a set of supporting documentation for each retail Participating Agency, corresponding to their respective chapters in Part 2. Documents for each agency include:
⚫ The DWR Retail UWMP Checklist verifying the agency has met UWMP Act requirements. ⚫ Proof of agency-specific public hearing notices and adoption resolutions. ⚫ The full text of the agency’s WSCP.
⚫ Completed DWR Submittal Tables specific to that agency. ⚫ Water supply agreements specific to that agency.

Reporting Structure
This 2025 RUWMP utilizes a layered reporting approach to satisfy both regional and individual requirements. This structure ensures consistency across agency-specific chapters while maintaining the necessary granularity for individual agency compliance. Figure 1-1 illustrates the relationship between the Regional Context (Part 1) and the Local Agency UWMPs (Part 2). Table 1-1 identifies the location of key UWMP data elements within this document.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 5

Figure 1-1. Regional Context vs. Local Agency UWMPs Relationship

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 6

Table 1-1. Regional vs. Individual Reporting Matrix
UWMP Requirement Part 1: Regional Context Part 2: Individual Agency Chapters System Description Regional Climate and
Demographics
Local Service Area Map and
Customer Class Data
Water Use (Demand) Aggregated Regional Demand
Totals
Agency-Specific Demand
Projections
SB X7-7 / AB 1668 Compliance General Regional Trends Specific Target Calculations and Compliance
Water Supply: Imported MWD Reliability and Wholesale
Allocation
Agency-Specific Purchase
Projections
Water Supply: Groundwater Basin Descriptions, Management, and Safe Yield
Agency-Specific Pumping Rights and
History
Water Supply: Recycled Regional Infrastructure and
Opportunities Agency-Specific Use and Projection
Water Supply Reliability Regional Water Budget
(Surplus/Deficit) Agency-Specific Reliability Tables
Drought Risk Assessment (DRA) Regional 5-Year Stress Test (2026- 2030) Agency-Specific 5-Year Stress Test
Water Shortage Contingency Plan Regional Summary and
Consistency
Full Agency WSCP Adoption and
Protocols
Demand Management Measures Regional Conservation Programs (TVMWD) Local Conservation Programs
Adoption and Submittal Regional Resolution (TVMWD) Individual Resolutions (Retailers) By utilizing this structure, the Participating Agencies ensure that the "Regional Context" serves as the substantiated technical foundation for the "Individual Agency UWMPs," resulting in a cohesive and defensible regional planning document.

1.3. Plan Preparation and Coordination
Management of water resources in the Three Valleys region takes place within a complex legal and institutional framework. Development of this RUWMP required comprehensive coordination involving the cooperation of many parties engaged in water management. TVMWD solicited public involvement in the planning process by presenting updates at scheduled workshops and Board meetings, as well as soliciting public comments on the draft RUWMP.

The successful development of this 2025 RUWMP required strong coordination between TVMWD, MWD, and its retail agencies. The planning process was structured to ensure clear communication, foster collaboration, and maintain transparency between all agencies and broader stakeholders.

1.3.1. Participating Agencies
The agencies participating in the development and adoption of this RUWMP are listed in Section 1 (Introduction). These eight agencies (TVMWD and seven retail agencies) actively collaborated to develop 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 7

the demand and supply projections, assess regional drought risk, and align water shortage communication protocols where feasible (though each agency retains its own independent WSCP).

In addition to the Participating Agencies, this RUWMP incorporates data from "Other Member Agencies" within the TVMWD service area. While these agencies are not co-authors or signatories to this specific RUWMP, their water demands draw from the same regional aqueducts and groundwater aquifers as the Participating Agencies; collectively, these agencies represent a significant portion of the region's total water demand. To accurately project whether the region can meet its needs through 2050, projections for these agencies were estimated based on publicly available data (such as Master Plans and previous UWMPs) and data provided to TVMWD as part of regular reporting and was incorporated into the regional analysis in Part 1.

These Other Member Agencies include:
⚫ Boy Scouts of America - Firestone Reservation / City of Industry ⚫ California Polytechnic University, Pomona
⚫ City of Covina
⚫ Mt. San Antonio College
⚫ Suburban Water Systems
⚫ Covina Valley Water Company
Among the Other Member Agencies, the City of Covina and Suburban Water Systems have prepared independent 2025 UWMPs, as mentioned in the Introduction.

1.3.2. Public Participation
The Participating Agencies encouraged public participation in the preparation of this Plan to ensure the public’s comments were considered in decisions about water management in the region. In accordance with the UWMP Act, the Participating Agencies issued a Notice of Plan Preparation to cities and counties within the region at least 60 days prior to the public hearing (notices distributed between March 13 and March 27, 2026). This notice informed stakeholders that the 2025 RUWMP was being prepared and invited input. Table 1-2 identifies the stakeholders notified of the 2025 RUWMP preparation.

Copies of these 60-day Notice of Preparation letters and the associated distribution lists are included in each Participating Agency’s Public Outreach appendix (Appendix [X]-2) in Part 4.

Prior to adoption, each Participating Agency provided notice to the public through its website and published announcements of the public hearing in a local newspaper once per week for two consecutive weeks. Copies of the proofs of publication for these public hearings are included in each Participating Agency’s Public Outreach appendix (Appendix [X]-2) in Part 4. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 8

Table 1-2. Stakeholders Notified of the Preparation of the 2025 RUWMP (60‑Day Notice) Agency/City/County Three Valleys
Municipal
Water District
City of
Glendora
City of
La Verne
City of
Pomona
GSWC -
Claremont
GSWC - San
Dimas
Rowland
Water District
Walnut Valley
Water District
Building Industry Association n/a n/a n/a n/a n/a n/a ✓ n/a Cal Poly Pomona ✓ n/a n/a n/a n/a n/a n/a n/a
Chino Basin Watermaster ✓ n/a n/a ✓ n/a n/a n/a n/a
City of Azusa ✓ ✓ n/a n/a n/a n/a n/a n/a
City of Claremont ✓ n/a ✓ ✓ ✓ n/a n/a n/a
City of Covina ✓ ✓ n/a n/a n/a ✓ n/a n/a
City of Diamond Bar ✓ n/a n/a n/a n/a n/a ✓ ✓
City of Glendora ✓ ✓ n/a n/a n/a ✓ n/a n/a
City of Industry ✓ n/a n/a n/a n/a n/a ✓ ✓
City of La Habra n/a n/a n/a n/a n/a n/a ✓ n/a
City of La Puente ✓ n/a n/a n/a n/a n/a ✓ n/a
City of La Verne ✓ n/a n/a n/a n/a ✓ n/a n/a
City of Montclair n/a n/a n/a n/a ✓ n/a n/a n/a
City of Pomona ✓ n/a ✓ ✓ ✓ n/a ✓ n/a
City of San Dimas n/a n/a ✓ n/a n/a ✓ n/a n/a
City of Upland n/a n/a n/a ✓ ✓ n/a n/a n/a
City of Walnut ✓ n/a n/a n/a n/a ✓ ✓ ✓
City of West Covina n/a n/a n/a n/a n/a n/a ✓ ✓
City of Whittier n/a n/a n/a n/a n/a n/a ✓ n/a
Covina Valley Water
Company ✓ ✓ n/a n/a n/a n/a ✓ n/a
Golden State Water Co. ✓ ✓ ✓ ✓ n/a n/a n/a n/a
Hacienda La Puente Unified
School District n/a n/a n/a n/a n/a n/a ✓ n/a
Inland Empire Utilities
Agency ✓ n/a n/a n/a n/a n/a n/a
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 9

Agency/City/County Three Valleys
Municipal
Water District
City of
Glendora
City of
La Verne
City of
Pomona
GSWC -
Claremont
GSWC - San
Dimas
Rowland
Water District
Walnut Valley
Water District
La Habra Heights County
Water District n/a n/a n/a n/a n/a n/a ✓ n/a
La Puente Valley County
Water District
n/a n/a n/a n/a n/a n/a ✓ n/a
Los Angeles County ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
Main San Gabriel Basin
Watermaster ✓ ✓ n/a n/a n/a n/a n/a n/a
Metropolitan Water District ✓ n/a n/a ✓ n/a n/a n/a n/a Mt. San Antonio College ✓ n/a n/a n/a n/a n/a n/a n/a
Pico Water District n/a n/a n/a n/a n/a n/a ✓ n/a
Rowland Unified School
District
n/a n/a n/a n/a n/a n/a ✓ n/a
Rowland Water District ✓ n/a n/a ✓ n/a n/a n/a ✓
Six Basins Watermaster ✓ n/a n/a ✓ n/a n/a n/a n/a
Suburban Water Systems ✓ ✓ n/a n/a n/a n/a n/a n/a
Sycamore Development
Partners
n/a n/a n/a n/a n/a n/a ✓ n/a
Three Valleys Municipal
Water District
n/a ✓ ✓ ✓ n/a n/a ✓ ✓
Upper San Gabriel Valley
Municipal Water District ✓ ✓ n/a n/a n/a n/a n/a n/a
Valley County Water District n/a n/a n/a n/a n/a n/a ✓ n/a Walnut Valley Water District ✓ n/a n/a ✓ n/a n/a ✓ n/a
Yorba Linda Water District n/a n/a n/a n/a n/a n/a ✓ n/a Note: n/a = not applicable.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 10

1.3.3. Stakeholder Workshops
Participating Agencies collaborated in the development of the Plan through a series of individual meetings and regional workshops to update elements of the Plan and review and provide feedback on preliminary results.

Individual Agency Data Collection
The data collection effort began with individual meetings between TVMWD planning staff and each of the seven retail Participating Agencies. These meetings were aimed at gathering granular data – including production numbers, consumption logs, and water loss audits – from the previous five fiscal years (FYs) 2021-2025). Following the initial data analysis, follow-up meetings were held with each agency to "ground-truth" their draft demand and supply projections. This iterative process allowed each agency to verify that their draft projections accurately reflected their specific portfolios, development plans, and operational constraints.

Regional Workshops
TVMWD hosted two regional workshops to facilitate data sharing and consensus among the agencies. ⚫ Workshop 1 (January 29, 2026): The first workshop brought together Participating Agencies and other non-participating agencies to review the 2025 RUWMP structure, confirm the regional supply and demand projections, and review the results of the DRA. The meeting agenda, sign-in sheets, and presentation materials for this workshop are included in Part 3, Appendix E. ⚫ Workshop 2 (April 2, 2026): A second workshop was held to review the Draft RUWMP and individual agency chapters prior to public release. This workshop focused on ensuring consistency across the agency-specific chapters (Part 2) and the regional roll-up (Part 1). The meeting agenda, sign-in sheets, and presentation materials for this workshop are included in Part 3, Appendix E.

1.4. Plan Adoption
The CWC requires that the UWMP be adopted by the governing body of each Participating Agency.

Before the Plan could be adopted, the agencies were required to notify the public and hold a public hearing to encourage community input.

Adoption Strategy (Part 1 vs. Part 2)
To ensure that each Participating Agency meets its individual regulatory obligations while benefiting from a coordinated regional approach, this RUWMP was structured to allow agencies to adopt the specific components relevant to their service area.
⚫ Three Valleys Municipal Water District (Lead Agency): Adopted Part 1 (Regional Context), Part 3 (Regional Supporting Information), and its specific wholesale agency chapter in Part 2. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 11

⚫ Retail Participating Agencies: Adopted Part 1, Part 3, and their respective individual agency chapter in Part 2 and local appendices in Part 4.

This structure ensures that the "Regional Context" (Part 1) serves as a common foundation for the Participating Agencies, while the "Individual Agency UWMPs" (Part 2) remain the specific responsibility of each local governing body.

Public Hearing and Resolution
Following the public noticing period described in Section 1.3, each Participating Agency held a public hearing to discuss the 2025 RUWMP and the WSCP. The hearings provided an opportunity for the public to comment on the agencies' water management strategies.

Following the public hearing, each agency’s governing body adopted the 2025 RUWMP and the 2025 WSCP via resolution. Table 1-3 summarizes the adoption dates and resolution numbers for each Participating Agency. Copies of the signed resolutions are included in Part 3, Appendix F (for the TVMWD Lead Agency resolution) and Part 4.

Table 1-3. Participating Agency RUWMP Adoption Dates and Resolutions Agency Public Hearing and Adoption Meeting
TVMWD June 3, 2026
City of Glendora May 26, 2026
City of La Verne May 18, 2026
City of Pomona May 18, 2026
GSWC (Claremont) May 26, 2026
GSWC (San Dimas) May 26, 2026
Rowland Water District May 19, 2026
Walnut Valley Water District May 18, 2026
Plan Submittal
In accordance with the UWMP Act, the Final 2025 RUWMP and WSCPs were submitted to DWR within 30 days of adoption and by the statutory deadline of July 1, 2026. The submittal was completed electronically using the DWR Water Use Efficiency Data (WUEdata) online portal.

Additionally, copies of the adopted Plan were submitted to the California State Library and the cities and counties within the region within 30 days of adoption. Transmittal receipts and letters are provided in Part 3, Appendix G.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 12

Amending the Plan
If the adopted 2025 RUWMP or WSCP requires amendment in the future, the agency proposing the amendment will follow the same procedures for notification, public hearing, adoption, and submittal as were used for the original Plan, in accordance with the CWC. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 13

2. Region Description
The Three Valleys Municipal Water District service area (Region) is located in the southeastern portion of Los Angeles County and covers a diverse landscape ranging from the foothills of the San Gabriel Mountains to the urbanized valley floors. This chapter describes the Region’s characteristics, including its physical setting, population demographics, land use, and regional climate.

This chapter also identifies the local agencies and water suppliers that have a role in managing water resources within the Region. These agencies work collaboratively to manage a complex portfolio of imported water, local groundwater, and local surface water to support a thriving regional economy and population. A detailed discussion of the water resources managed within the Region is provided in Chapter 3 (Regional Water Sources and Management).

2.1. Regional Setting
The Region is defined by the service area of TVMWD, which encompasses approximately 133 square miles. The Region derives its name from the three primary valleys that make up its service area: the Pomona Valley, the Walnut Valley, and the eastern portion of the San Gabriel Valley. Figure 2-1 summarizes this Region and its surrounding area.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 14

Figure 2-1. Map of TVMWD Service Area

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 15

Geographically, the Region is bordered by the San Gabriel Mountains to the north, which provide a critical watershed for local surface flows and spreading grounds. To the east, the Region is bounded by the San Bernardino County line; to the south, by the Puente Hills and Orange County line; and to the west, by the San Gabriel River and the main San Gabriel Valley urbanized corridor.

The topography of the Region varies significantly, ranging from rugged foothill terrain in the north (Claremont, Glendora, La Verne) to the gently sloping valley floors where the majority of the residential and commercial development is located. This variation in terrain influences the Region's water management strategies, particularly regarding groundwater recharge capability and pressure zone management for water distribution.

The Region is a highly urbanized to semi-urbanized area that serves as a transition zone between the greater Los Angeles metropolitan area and the Inland Empire. It is traversed by major transportation corridors, including Interstates 10 and 210 and State Route 57, which have historically driven population growth and economic development in the area. Despite its urbanization, the Region maintains significant connection to natural resources, particularly along the northern foothill interface, which also presents specific climate vulnerabilities such as wildfire risk.

2.2. Water Agencies in the Region
Management of the Region's water resources involves a hierarchy of water suppliers, including a regional wholesaler and multiple retail agencies. TVMWD acts as the regional wholesaler, bridging the gap between the imported water supplies from MWD – a regional wholesale cooperative responsible for importing and managing Colorado River and State Water Project (SWP) supplies for Southern California – and the retail agencies that serve residents and businesses. The retail agencies include municipalities, special districts, investor-owned utilities, and mutual water companies, each responsible for the direct management of water supply distribution, local groundwater extraction, and customer service.

2.2.1. Water Supply Managers, Wholesalers, and Retailers TVMWD is a public agency formed by election of voters in 1950. As a member agency of MWD, TVMWD is the primary wholesale water supplier for the Region. TVMWD is responsible for long-range regional water supply management, including the importation of supplemental water from the SWP and the Colorado River Aqueduct (CRA) via MWD. TVMWD manages the transmission pipelines and treatment facilities necessary to deliver this imported water to its member agencies. Additionally, TVMWD plays a critical role in regional groundwater management by coordinating connection to MWD’s replenishment programs for the Main San Gabriel, Chino, and Six Basins.

Regional Water Agencies
There are 13 retail water agencies and/or community water systems operating within the TVMWD service area. These agencies vary in size and governance structure, but all rely on the common regional resources managed in this Plan.

For the purposes of this 2025 RUWMP, the retail agencies are categorized into two groups:
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 16

1. Participating Agencies: Seven retail agencies actively participated in the development of this Plan. Detailed descriptions of their specific service areas, water use, and supply reliability are provided in their respective chapters in Part 2 of this Plan.

2. Other Member Agencies: Six additional agencies operate within the Region. While these agencies are not signatories to this specific RUWMP, their water demands represent a significant portion of the regional total. Therefore, their supply and demand data has been estimated and included in the Regional Context (Part 1) analysis to ensure an accurate assessment of total regional reliability.

Table 2-1 summarizes the water agencies within the Region.

Table 2-1. Water Management Agencies in the TVMWD Region Agency Name Agency Type RUWMP Status
Three Valleys Municipal Water District Special District (Wholesaler) Lead Agency City of Glendora Municipality Participating Agency
City of La Verne Municipality Participating Agency
City of Pomona Municipality Participating Agency
Golden State Water Co. (Claremont) Investor-Owned Utility Participating Agency Golden State Water Co. (San Dimas) Investor-Owned Utility Participating Agency Rowland Water District Special District Participating Agency Walnut Valley Water District Special District Participating Agency City of Covina Municipality Other Member Agency
Suburban Water Systems Investor-Owned Utility Other Member Agency Covina Valley Water Company Retail
(Formally Valencia Heights Water Company) Mutual Water Company Other Member Agency Cal Poly Pomona State University Other Member Agency
Mt. San Antonio College Community College Other Member Agency Boy Scouts (Firestone Reservation) Non-Profit/Institutional Other Member Agency

2.3. Population and Demographics
Understanding the demographic makeup and growth trajectory of the TVMWD service area is essential for accurately projecting future water demands, designing effective conservation programs, and developing equitable long-term water management strategies. While the Region experienced periods of rapid residential and commercial expansion throughout the late 20th century, recent demographic data indicates a transition toward stabilized, modest population growth driven primarily by urban infill and redevelopment.

2.3.1. Historic Population Growth
The Region covers the eastern part of Los Angeles County, as well as the eastern half of the San Gabriel Valley. Because of the San Gabriel Valley’s close relationship with the economy and job market of the general Los Angeles region, economic trends that affect housing demands and job growth in Los Angeles 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 17

can be generally applied to San Gabriel Valley and the TVMWD service area. Historic U.S. Census population values and average annual growth rates for Los Angeles County are shown in Table 2-2. and Figure 2-2. Between 1980 and 2000, Los Angeles County grew rapidly, adding nearly 140,000 people each year from 1980 to 1990. By 2000, growth slowed and has been flattening out, gaining only 20,000 people per year from 2010 to 2020. Going forward, the population of Los Angeles County is projected to decline through 2050, as discussed in the following section.

Table 2-2. Los Angeles County Population, 1980 to 2020
Los Angeles County Population 1980 1990 2000 2010 2020
Population 7,477,239 8,863,052 9,519,315 9,818,605 10,014,009 Average Annual % Increase 1.71% 0.72% 0.31% 0.20%
Annual Average Population
Increase, people per year
139,000 66,000 30,000 20,000
Figure 2-2. Los Angeles County Population, 1980 to 2020

U.S. Census data indicate the TVMWD service area has experienced somewhat slower population growth than the greater Los Angeles County area. The Census populations for the TVMWD service area and annual average growth rates are shown in Table 2-3.

Table 2-3. TVMWD Population, 1990 to 2020
TVMWD Population 1990 2000 2010 2020
Population 474,112 508,711 506,446 515,688
Average Annual % Increase 0.71% (0.04%) 0.18%
Annual Average Population Increase, people per year 3,460 230 920 0 2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
1980 1985 1990 1995 2000 2005 2010 2015 2020
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 18

2.3.2. Future Population Projections
According to the California Department of Finance projections, the population of Los Angeles County is projected to decline from 2025 to 2050, as shown in Table 2-4 (DOF, 2025).

Table 2-4. Los Angeles County Projected Population, 2025 to 2050 Projected Population 2025 2030 2035 2040 2045 2050
Population 9,853,842 9,867,515 9,840,458 9,775,762 9,684,285 9,554,157 Average Annual % Increase (0.32%) 0.03% (0.05%) (0.13%) (0.19%) (0.27%) Annual Average Population
Change, people per year
(32,000) 3,000 (5,000) (13,000) (18,000) (26,000)
To project population for the TVMWD service area, the Southern California Association of Governments (SCAG) demographics and growth forecast for the 2024 Connect SoCal Regional Transportation Plan (RTP) were used (SCAG, 2024). These projections include estimated population, households, and employment in 2019, 2035, and 2050 inside each of the approximately 13,062 traffic analysis zones (TAZs) that cover the SCAG region. SCAG publishes data per jurisdiction and TAZ as GIS shapefiles. This data is intersected with supplier service areas to provide an estimate of population within service areas for 2019, 2035, and 2050. SCAG prepares demographic forecasts based on land use data for their region and outside sources such as the 2020 Census and Regional Housing Needs Assessment (RHNA). SCAG incorporates essential land use planning information to reflect anticipated future populations and land uses.

In 2022, SCAG launched the Local Data Exchange (LDX), a tool where jurisdictions can directly input their data. This change has increased data input, participation, and validation for the 2019, 2035, and 2050 projections. SCAG’s projections undergo extensive local review, incorporating zoning information from city and county general plans, input from local planners and jurisdictions, and coordination with local or regional land use authorities.

SCAG’s 2024 population growth projections have declined from the last Connect SoCal RTP in 2020, due to ongoing economic impacts of COVID-19, pandemic-related death increases, increasingly negative net domestic migration, decline in births, and near-zero level of foreign immigration. SCAG’s 2024 update uses a 2019 base year and incorporates a broader data range from 2016 to 2022, capturing key post- COVID shifts in population, employment, and household trends.

Figure 2-3Table 2-5 provides a comparison of population projections from the 2020 and 2024 Connect SoCal RTP. While 2024 SCAG projects slower growth, the result still shows a minor increase in population within the TVMWD service area, which is estimated to grow by about 30,000 people by 2050 from a 2020 Census value of 515,688. Table 2-5 shows 2024 Connect SoCal RTP projections along with a percent growth rate from 2030 to 2050. Table 2-6. and Table 2-7 show SCAG projections of households and employment (jobs) for the TVMWD service area, respectively. Near-term employment trends are discussed in more detail in the next section.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 19

Table 2-5. Projected Population for the Region (2030 to 2050) Projected Population 2030 2035 2040 2045 2050
Total 532,566 538,918 541,174 543,431 545,688
% Growth Rate 0.24% 0.08% 0.08% 0.08%
Figure 2-3. Connect SoCal RTP Population Projection Comparison

Table 2-6. Projected Household for the TVMWD Service Area (2019 to 2050) Projected Households 2019 2035 2050
Total 159,913 183,170 188,818
% Growth Rate 0.85% 0.19%
Table 2-7. Projected Employment for the TVMWD Service Area (2019 to 2050) Projected Jobs 2019 2035 2050
Total 233,679 243,785 245,538
% Growth Rate 0.26% 0.04%

2.3.3. Other Demographic Information
The Region comprises about half of the San Gabriel Valley, on the eastern portion of the Los Angeles County as described in Section 2.3.1. Economic conditions in the Region can be reflected by the 2025 San Gabriel Valley Economic Forecast prepared by the San Gabriel Valley Economic Partnership and Cal Poly Pomona (SGVEP & Cal Poly Pomona, 2025). Overall, the Region has been experiencing a slowdown in economic growth for 2025, due to the effects of the COVID-19 pandemic. Like most communities in Southern California, the post-pandemic recovery period is still present today. -
100,000
200,000
300,000
400,000
500,000
600,000
2025 2030 2035 2040 2045 2050
2020 Connect SoCal RTP 2024 Connect SoCal RTP
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 20

Currently, the San Gabriel Valley is experiencing long-term economic impacts from wildfires, such as displacement of residents, business disruption, and rebuilding costs. The San Gabriel Valley was affected by multiple wildfires in January of 2025, burning over 38,000 acres of Los Angeles County. A high demand of housing and rental increases have left residents to be displaced or migrate out of the San Gabriel Valley. The forecast indicates that most rebuilding activity is expected to occur over multiple years rather than in the near term. The San Gabriel Valley is expected to continue experiencing the economic effects of the wildfires over the coming years.

In developing the economic forecast, the San Gabriel Valley considered three major factors observed over the past year: wildfires, tariffs, and federal layoffs. Without these factors, total nonfarm employment was expected to grow steadily by approximately 0.4 percent, with job gains concentrated in the healthcare, transportation, and warehousing sectors. When these impacts are incorporated, however, 2025 is projected to result in a loss of approximately 6,500 nonfarm jobs, representing a 0.9 percent decline across the San Gabriel Valley. Manufacturing has been the sector most affected, with an estimated 2,900 jobs lost, accounting for roughly 5.7 percent of the sector’s workforce. Looking ahead, total nonfarm employment is projected to rebound by approximately 4,800 jobs (0.7 percent) by 2027, relative to 2025 levels.

Disadvantaged Communities
In accordance with DWR guidance, a community is classified as a disadvantaged community (DAC) if its median household income is below 80 percent of the statewide Median Household Income (MHI) for California. The current dataset used by DWR in the DAC Mapping Tool is the U.S. Census American Community Survey 5‑Year data for the 2018–2023 period (U.S. Census Bureau, 2024). Based on this dataset, the statewide MHI is $63,783, resulting in a DAC income threshold of $77,067.

A substantial number of census tracts within the Region are identified as DACs. The largest concentration of DACs is located in the eastern portion of the Region in the City of Pomona to the western portion in the Cities of Walnut and Rowland Heights, with additional DAC areas present in portions of the City of La Verne. Smaller, dispersed DAC areas are also located throughout the Region.

Many DAC residents within the Region are served by public water systems and receive water supplies that meet all applicable state and federal drinking water quality standards from the water agencies serving their communities. While water quality standards are met, affordability remains a challenge in some DAC areas. Communities with the highest concentrations of DAC residents have implemented assistance programs to help households manage water‑related costs while continuing to ensure that water and wastewater services comply with all state and federal regulatory requirements.

2.4. Land Uses
Land use patterns within the Region are a primary driver of water demand, particularly regarding outdoor irrigation needs. As described in Section 2.1, the Region covers approximately 133 square miles characterized by a diverse mix of developed urban landscapes and natural foothill terrain. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 21

The valley floors (Pomona, Walnut, and San Gabriel Valleys) are largely built-out and urbanized. The predominant land use in these areas is residential, consisting of a mix of low-density single-family homes (which historically drive higher per capita water use due to landscaping) and medium-to-high density multi-family developments. Current land use trends focus on redevelopment, "in-fill" projects, and densification (such as the addition of Accessory Dwelling Units). The northern boundary of the Region, defined by the foothills of the San Gabriel Mountains, remains largely comprised of protected open space and low-density residential interface zones. The Region also supports significant commercial and light industrial corridors, particularly along Interstates 10 and 210 and State Route 57.

A unique characteristic of the Region is the presence of major institutional land uses. The area is home to several large educational institutions, including California State Polytechnic University, Pomona (Cal Poly Pomona), Mt. San Antonio College (Mt. SAC), and the Claremont Colleges. These campuses represent distinct water use profiles, often managing large, landscaped areas, independent water infrastructure systems, and substantial demand shifts that correspond with instructional sessions and breaks.

Planning Coordination
While TVMWD and its Participating Agencies manage water supplies, most of them do not have land use authority. The authority to approve General Plans, Specific Plans, and zoning designations lies with the local municipalities (e.g., City of Pomona, City of Glendora) and Los Angeles County.

However, the California Government Code requires coordination between land use and water planning.

The Participating Agencies generally voluntarily comply with local building codes and standards.

Furthermore, the demand projections utilized in this Plan (and discussed in Section 4) rely on growth forecasts from the SCAG, which are derived from the local land use plans of the cities and counties within the Region (SCAG, 2024). SCAG conducts coordination with land use agencies as part of its regional forecast cycles. Figure 2-4 and Table 2-8 show the land uses within the Three Valley Region. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 22

Figure 2-4. Regional Land Use Map

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 23

Table 2-8. Approximate Regional Land Use Distribution
Land Use Category Description Approximate % of
Service Area
Single-Family Residential Detached homes, typically with outdoor landscaping 38% Multi-Family Residential Apartments, condos, townhomes 5% Commercial / Industrial Retail, office parks, manufacturing, logistics 16% Institutional Schools, universities, hospitals, government facilities 6% Open Space / Vacant Foothills, parks, spreading grounds, undeveloped land 35% Agriculture Remnant agricultural parcels (e.g., Cal Poly campus) <1%

2.5. Regional Climate
The climate within the Region is characterized as "Mediterranean," consisting of hot, dry summers and mild, wet winters. This seasonal pattern is the primary driver of the Region's water demand profile:
water use typically peaks in the summer months (July through September) due to high outdoor irrigation demands and drops in the winter months (December through March) when rainfall is more prevalent and evaporation rates are lower.

The Region’s local hydrology is heavily influenced by the San Gabriel Mountains to the north. These mountains act as a barrier to storm systems, creating an orographic effect that results in higher precipitation totals in the foothills compared to the valley floor. Surface water supplies from the San Gabriel River and San Antonio Creek account for approximately 2 percent of the Region’s water supply portfolio and are directly dependent on this mountain precipitation and snowpack. Recycled water, which is largely independent of local precipitation, accounts for an additional 4 percent of the regional supply.

2.5.1. Current Regional Climate
The Region has extensive historical climate records used for planning. For evaluating historical hydrologic extremes and long-term variability, the Glendora West Station gauge serves as a key benchmark, with records dating back to 18832. Historical analysis of this station indicates significant variability in the Region, with annual rainfall ranging from a low of 7.67 inches (1961) to a high of 46.55 inches (1978).

While the Glendora West Station provides an excellent centennial record for precipitation, it does not capture the full suite of climatological data necessary for modern demand modeling. Therefore, to establish the current baseline for average monthly temperatures, precipitation, and reference evapotranspiration (ETo), the Region utilizes data from the California Irrigation Management Information System (CIMIS) Station 78, located in Pomona (DWR, 2026b). Table 2-9 summarizes these baseline climate characteristics for the Region for the last 35 years (1990-2025). This specific timeframe

2 https://wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca7050
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 24

was selected because it represents the full period of continuous, reliable data available for CIMIS Station 78.

Table 2-9. Regional Climate Characteristics (Jul 1990 – Sep 2025) Month Average
Temperature (°F)
Average
Minimum
Temperature (°F)
Average
Maximum
Temperature (°F)
Average Total
Precipitation
(Inches)
ETo
(Inches)
January 53.6 42.3 67.3 3.1 1.99
February 54.3 43.0 67.2 3.4 2.37
March 56.7 45.1 69.7 2.3 3.73
April 59.7 47.4 73.1 1.0 4.74
May 63.3 52.4 76.0 0.4 5.20
June 68.2 56.8 82.0 0.2 5.96
July 73.0 60.7 87.8 0.2 6.74
August 74.0 60.9 89.7 0.3 6.59
September 71.5 58.9 87.0 0.5 4.99
October 65.3 53.1 80.3 0.8 1.94
November 58.2 46.0 73.4 1.1 2.39
December 52.5 41.3 66.7 2.5 1.77
Annual 62.5 50.6 76.7 15.9 48.41
Source: California Department of Water Resources, CIMIS Station 78 (Pomona) (DWR, 2026b) As shown in the table, the Region's climate creates a significant structural imbalance between natural water supply and outdoor water demand. Annual ETo (48.41 inches) is more than three times the average annual precipitation (15.9 inches). This significant deficit necessitates the application of supplemental irrigation to maintain landscaping and agriculture throughout the majority of the year.

Precipitation is highly concentrated, with approximately 71 percent of the average annual rainfall (11.3 inches) occurring in a four-month window between December and March. Conversely, the summer months (June through September) experience negligible precipitation (less than 1 inch combined) while accounting for the highest ETo rates, peaking at 6.74 inches in July.

2.5.2. Potential Effects of Climate Change
Climate change adds a layer of uncertainty to the Region’s future water supply reliability. As part of development of TVMWD’s 2025 Water Resources Master Plan (WRMP) (TVMWD, 2025) (included in Part 3, Appendix H), TVMWD completed a Climate Change Vulnerability Assessment (Climate Assessment) in July 2024 (TVMWD, 2024a) (the Climate Assessment is included in Part 3, Appendix I).

The Climate Assessment utilized data from DWR and 20 global climate models to project impacts on the Region’s water supplies and demands through 2045.

The assessment evaluated three potential future scenarios: (1) Drier with Extreme Warming ("Dry Hot"), (2) Median Future Conditions, and (3) Wetter with Moderate Warming ("Wet Warm"). Key climate change impacts identified in the standalone 2024 Climate Assessment include:
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 25

⚫ Increased Temperatures and Outdoor Demand: Regional increases in average maximum temperatures are projected to reach approximately 4°F to 5°F by the mid-21st century. This warming trend is expected to increase evapotranspiration (ET) rates for landscaping and crops.

Under the "Dry Hot" scenario, average annual outdoor water demand in the Region is projected to increase by approximately 5.8 percent by 2045. When combined with population growth, total water demand in the service area could increase by up to 15 percent under this scenario compared to baseline conditions.
⚫ Hydrologic Volatility and Shorter Rainy Seasons: While the total volume of annual precipitation may not decrease drastically (projected decrease of 6.5 percent under Dry Hot conditions), the timing of rainfall is expected to shift. The Region is projected to experience a shorter rainy season with higher intensity precipitation events. This volatility poses a challenge for local spreading grounds, as storm flows may occur in peaks that exceed the immediate capacity of diversion facilities, potentially reducing the volume of water successfully captured for groundwater recharge.
⚫ Reduced Local Surface Water: Under the “Dry Hot” scenario, flows in the San Gabriel River are projected to decrease by approximately 10 percent by 2045. This reduction directly impacts the availability of local surface water for treatment and groundwater replenishment. ⚫ Increased Reliance on Imported Water: Due to the projected stabilization or slight decrease in local supplies (groundwater and surface water) combined with the climate-driven increase in demand, the Region’s reliance on imported water from MWD is projected to increase. The Climate Assessment indicates that imported water supply requirements could increase by approximately 15,400 acre-feet per year (AFY) by 2045 under extreme warming conditions.

While the 2024 Climate Assessment established the foundational vulnerabilities summarized above (using modeled theoretical demands through 2045), TVMWD and the Participating Agencies opted to utilize a more rigorous, hybrid analytical approach for the actual supply and demand projections presented in this 2025 RUWMP (which extends to 2050, as detailed in Chapter 5).

To ensure operational accuracy through 2050, the climate change factors derived from the Climate Assessment were updated through 2050 and applied directly to scale the future availability of local supplies. Conversely, rather than relying solely on modeled theoretical demand increases, this RUWMP projects future drought demands using empirical stress-test data. As described in Chapter 5, the relationship between actual elevated water use during the historical 2018–2022 drought and the 2021– 2025 average baseline was used to establish localized drought scaling factors.

By applying these updated Climate Assessment climate factors through 2050 to the supply side and empirical historical scaling factors to the demand side, this RUWMP provides a conservative, operationally grounded assessment of the Region's reliance on imported water through 2050. Because of this shift from 2045 theoretical modeling to 2050 empirical historical scaling, the final volumetric projections in Chapter 5 supersede the preliminary 2045 estimates cited in the Climate Assessment summary above.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 26

3. Regional Water Sources and Management
Securing a reliable water supply is the primary mission of TVMWD and its Participating Agencies. The Region relies on a diversified portfolio of water assets to meet the needs of its residential, commercial, and institutional customers.

Based on the regional baseline established for this Plan (2021–2025), the Region’s water supply portfolio consists of:
⚫ Imported Water (approximately 50%): Primarily water purchased from the MWD originating from the Colorado River and the SWP. This is supplemented by other imported or wholesale purchases from neighboring municipalities and mutual water companies. ⚫ Local Groundwater (approximately 44%): Groundwater extracted from the Main San Gabriel, Chino, Six Basins, Spadra, Central, and Puente basins.
⚫ Recycled Water (approximately 4%): Treated wastewater utilized for non-potable demands. ⚫ Local Surface Water (approximately 2%): Surface flows diverted from the San Gabriel River and San Antonio Creek.

This chapter describes the current and planned water resources available to the Region through 2050. It also details the management frameworks – including legal judgments, Watermasters, and regional agreements – that govern how these resources are extracted, stored, and shared among the agencies.

Regional Water Supply Portfolio Overview
While the percentages above represent the aggregate regional supply, the specific water supply portfolios vary significantly among the individual retail agencies. Because of the Region's diverse geography, hydrogeology, and historical infrastructure development, each agency relies on a unique combination of imported water, groundwater, surface water, and recycled water.

For example, agencies located in the northern foothills may have access to local surface water diversions, while agencies in the southern portion of the Region may rely more heavily on imported water and recycled water. This diversity is a regional strength. However, it also means that each agency is impacted differently by drought, regulatory shifts, or infrastructure constraints.

Table 3-1 provides a high-level overview of the water sources currently utilized by each agency within the TVMWD service area.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 27

Table 3-1. Overview of Water Sources Used by TVMWD Member Agencies Agency Groundwater Imported
Water
Surface
Water
Recycled
Water
Participating Agencies (RUWMP Co-Authors) n/a n/a n/a n/a City of Glendora ✓ ✓ n/a n/a
City of La Verne ✓ ✓ n/a n/a
City of Pomona ✓ ✓ ✓ ✓
Golden State Water Company (Claremont) ✓ ✓ n/a n/a
Golden State Water Company (San Dimas) ✓ ✓ n/a n/a
Rowland Water District ✓ ✓ n/a ✓
Walnut Valley Water District ✓ ✓ n/a ✓
Other TVMWD Agencies n/a n/a n/a n/a
Boy Scouts of America n/a ✓ n/a n/a
Cal Poly Pomona ✓ ✓ n/a ✓
City of Covina n/a ✓ n/a n/a
Mt. San Antonio College n/a ✓ n/a n/a
Suburban Water Systems ✓ ✓ n/a ✓
Covina Valley Water Company Retail
(Formally Valencia Heights Water Company)
✓ ✓ ✓ n/a
Note: Some agencies purchase local surface water or groundwater that has been treated and delivered by third-party mutual water companies, such as the Covina Valley Water Company. n/a = not applicable.

3.1. Imported Water
Imported water is the single largest source of supply for the Region. While several retail agencies’ supply portfolios include external wholesale purchases (detailed in Section 3.1.4), the vast majority of the Region's imported water is provided by TVMWD. TVMWD is a member agency of MWD, a regional wholesaler that delivers water to 26member public agencies across Southern California. MWD imports water from two primary sources: the Colorado River via the CRA and the Sacramento-San Joaquin Bay- Delta via the SWP.

TVMWD purchases both treated and untreated imported water from MWD. Treated water is delivered directly to retail agencies through service connections to the MWD distribution system. Untreated water is delivered to TVMWD’s Miramar Water Treatment Plant for treatment and distribution or used for groundwater replenishment in the Main San Gabriel and Six Basins.

3.1.1. Supply Description and Management
MWD’s primary sources of water are the Colorado River and the SWP. To secure these supplies against drought, regulatory restrictions, and climate change, MWD continues to invest in a diverse resource mix, including storage (such as Diamond Valley Lake), water transfers, and conservation programs. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 28

Colorado River Aqueduct
The CRA transports water 242 miles from Lake Havasu to Lake Mathews in Riverside County. MWD’s entitlement to Colorado River water is established by the "Law of the River," a collection of compacts, federal laws, and court decrees. Although MWD’s base apportionment is 550,000 AFY, MWD supplements this supply through agricultural conservation programs (such as the agreement with the Palo Verde Irrigation District) and storage programs in Lake Mead.

It is important to note that due to hydraulic constraints in the regional distribution system, several of TVMWD’s member agencies are located in "SWP Dependent Areas." These areas (including parts of the cities of Glendora and La Verne) cannot receive Colorado River water and are solely dependent on supplies from the SWP.

State Water Project
The SWP, managed by DWR, transports water from Northern California to Southern California via the California Aqueduct. MWD is the largest contractor of the SWP, with a maximum Table A allocation of 1,911,500 AFY.

Actual SWP deliveries vary annually based on hydrology, reservoir storage in Northern California, and environmental regulations in the Sacramento-San Joaquin Delta. To manage this variability, MWD utilizes its significant storage capacity (surface reservoirs and groundwater banking) to store surplus water during wet years for use during dry years.

TVMWD Access to Imported Water
Historically, TVMWD accessed MWD supplies through a Purchase Order structure with tiered rates.

However, MWD recently transitioned to a single volumetric rate structure (MWD 2025, 2026a). Over the most recent five-year baseline period (2021–2025), TVMWD’s annual imports have averaged approximately 55,600 AFY. TVMWD continues to coordinate closely with MWD to ensure reliable, cost- effective access to imported supplies.

3.1.2. Supply Reliability and Climate Impacts
The amount of water delivered through the SWP and CRA in any given year is highly dependent on statewide hydrology, snowpack, and regulatory constraints (such as pumping restrictions in the Sacramento-San Joaquin Bay-Delta to protect endangered species). During severe, multi-year droughts, allocations from the SWP have historically dropped as low as 5 percent of contracted amounts (e.g., in 2014 and 2021). Furthermore, the Colorado River Basin has experienced a prolonged two-decade drought, leading to historic shortage declarations by the U.S. Bureau of Reclamation.

MWD Storage and Reliability Mitigation
If TVMWD relied solely on the annual yield of the SWP and CRA, the Region would face severe structural deficits during droughts. However, MWD has invested billions of dollars in a massive regional storage portfolio – including Diamond Valley Lake (DVL), Lake Mathews, Lake Skinner, and extensive Central Valley and Mojave groundwater banking programs.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 29

Entering the 2026 planning cycle, MWD’s storage reservoirs are situated at near-record highs, holding nearly 4 million acre-feet (MAF) of water. As summarized in Table 3-2, MWD’s 2025 UWMP reliability modeling (provided in Part 3, Appendix J) demonstrates that even with severe cutbacks on SWP and Colorado River supplies, MWD possesses sufficient storage reserves to meet all wholesale member agency demands without triggering mandatory shortage allocations over the next five years, and projects 100 percent supply capability through 2050 under all modeled drought scenarios (MWD, 2026b).

Table 3-2. Projected Availability of TVMWD Wholesale Imported Supplies (from MWD) Hydrologic
Scenario
MWD Base Allocations
(SWP and CRA)
MWD Storage Withdrawals (DVL,
Groundwater Banks)
TVMWD Projected
Imported Reliability
Normal Year Average to High Minimal (Net Storage Accumulation) 100% of Demand Met Single Dry Year Constrained High (Storage Drawn Down) 100% of Demand Met 5-Year Drought Severely Constrained Maximum (Sustained Storage Drawdown) 100% of Demand Met Infrastructure Constraints: SWP-Dependent Areas
While MWD’s aggregate supply is highly reliable, TVMWD must navigate localized infrastructure constraints. Due to pipeline elevations and network physics, certain northern portions of the TVMWD service area – specifically serving the City of Glendora and the City of La Verne – are classified as "SWP- Dependent Areas." These zones cannot physically receive treated Colorado River water.

When SWP allocations are severely constrained during extreme droughts, MWD cannot simply substitute CRA water for these agencies. To maintain reliability in these specific zones, TVMWD and the Participating Agencies rely on local groundwater extraction, shifting supplies via the Pomona-Walnut- Rowland Joint Water Line (JWL), and utilizing TVMWD's cyclic storage accounts in the Main San Gabriel and Six Basins to offset the localized imported deficit.

To mitigate these constraints, MWD is actively constructing and planning a suite of infrastructure projects under its Capital Investment Plan designed to physically push stored water into SWP-Dependent Areas during extreme droughts.

For the eastern portion of the MWD’s service area – which directly benefits TVMWD's SWP-dependent agencies like the cities of the Glendora and La Verne – MWD is constructing the Diamond Valley Lake (DVL) to Rialto Pipeline Delivery Project (anticipated completion in late 2028). This project utilizes the Wadsworth Pumping Plant to pump stored water from DVL (which includes both banked SWP and Colorado River water) north into the Rialto Pipeline, reducing the area's strict reliance on real-time California Aqueduct flows and enhancing drought reliability.

Additionally, MWD’s 2025 UWMP identifies additional regional projects to provide relief to SWP- Dependent Areas across Southern California. These include west-side distribution upgrades – such as the Sepulveda Feeder Pumping Station and Greg Avenue Pump Station expansions – which reverse flow to push treated water into areas normally reliant on the West Branch of the SWP. Regionally, MWD is also advancing Pure Water Southern California, a massive, advanced water purification project that could produce up to 150 million gallons per day (MGD) of new supply. MWD is planning over 50 miles of large- 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 30

diameter pipeline from Carson to La Verne to provide raw water augmentation directly into the Weymouth Water Treatment Plant, which would further reduce the Region's demand for imported SWP supplies and increase reliability for TVMWD.

MWD Supply Reliability Modeling
As the regional wholesaler, MWD is responsible for projecting the reliability of imported water supplies for its member agencies. In its 2025 Draft UWMP, MWD assessed its ability to meet demands under normal, single-dry, and five-year consecutive drought conditions through the year 2050 (MWD, 2026b).

MWD’s analysis incorporates DWR’s Delivery Capability Report (DCR) CalSim models (DWR, 2025) and accounts for potential future constraints on the Colorado River. MWD’s modeling demonstrates that, through the implementation of its Integrated Resources Plan, which includes active conservation, local resource development, and storage management, it has sufficient supply capabilities to meet all projected member agency supplemental water demands through 2050, even under a repeat of historic drought conditions.

Based on MWD’s reliability assessment, TVMWD projects that imported water will be 100 percent reliable to meet the projected demands of its Participating Agencies through the planning horizon of this RUWMP.

3.1.3. Imported Water Quality
MWD is responsible for managing the water quality of the SWP and CRA and providing treated and untreated water that meets or exceeds all regulatory standards. The water quality of the SWP and CRA differ significantly, and the proportion of each source delivered to TVMWD fluctuates based on hydrology, MWD operational decisions, and drought conditions.

State Water Project Quality
Water imported via the SWP originates in the Sierra Nevada and flows through the Sacramento-San Joaquin Bay-Delta. SWP water is generally characterized by lower salinity, with Total Dissolved Solids (TDS) typically ranging from 250 to 350 milligrams per liter (mg/L). However, as water flows through the Sacramento-San Joaquin Bay-Delta, it picks up organic carbon and bromide. When treated with chlorine, these natural constituents can react to form Disinfection Byproducts (DBPs), which are strictly regulated by the EPA. SWP supplies are also susceptible to seasonal algal blooms, which can cause harmless but noticeable taste and odor issues, as well as suspended solids from winter storm runoff.

Colorado River Aqueduct Quality
Water imported via the CRA generally contains higher mineral content and salinity. TDS levels in CRA water are typically twice as high as SWP water, averaging between 580 mg/L and 620 mg/L, and can spike up to 700 mg/L or higher during prolonged droughts in the Colorado River Basin. In addition to higher hardness and salinity, the Colorado River watershed has historically faced localized challenges with perchlorate, uranium, and chromium-6, though MWD actively manages and monitors these constituents to ensure they remain well below regulatory limits prior to delivery. The CRA system also 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 31

requires aggressive management to control the spread of invasive Quagga mussels, which can clog intake and delivery infrastructure.

Salinity Management and Blending Strategies
Salinity is a critical water quality metric for the Region. High TDS in imported water not only affects the aesthetic quality (hardness) of drinking water but also has cascading impacts on the Region's local resources. When high-TDS imported water is used indoors, it increases the salinity of the wastewater sent to local reclamation plants. This, in turn, increases the salinity of the recycled water produced, which can limit its use for landscape irrigation and groundwater recharge due to strict Regional Water Quality Control Board Basin Plan objectives.

To mitigate this, MWD attempts to blend CRA water with lower-salinity SWP water to achieve a target TDS of approximately 500 mg/L for its treated water deliveries. However, during severe drought years when SWP allocations are drastically reduced, MWD must rely more heavily on the CRA. During these periods, TVMWD and its retail agencies experience higher salinity in their imported supplies.

Local Treatment and Operations
While MWD delivers some pre-treated water directly to TVMWD’s retail agencies for potable use, TVMWD also purchases raw, untreated imported water. TVMWD is responsible for treating this raw water at the Miramar Water Treatment Plant (MWTP) located in Claremont. The MWTP utilizes conventional filtration and disinfection processes to meet all Division of Drinking Water (DDW) standards before distributing the water to member agencies. The MWTP has a design capacity of 25 MGD and is undergoing continuous modernization, including planned upgrades to incorporate Granular Activated Carbon (GAC) into its filter basins to proactively address contaminants of emerging concern.

Additionally, untreated imported water is delivered to the Covina Valley Water Company (CVWC), which treats the water at its William B. Temple Treatment Plant prior to supplying it to local agencies in the western portion of the Region. Both TVMWD and CVWC must dynamically adjust their treatment plant operations to handle the shifting water quality profiles of MWD's blend of SWP and CRA water.

3.1.4. Other Imported and Purchased Water Supplies
While TVMWD/MWD supplies constitute the vast majority of imported water in the Region, several retail agencies rely on external imports, wholesale purchases, and inter-agency transfers to meet their localized demands. To accurately capture the Region's total water portfolio in the supply and demand assessments (Section 5), these distinct supplies are categorized collectively as "Imported Water (Other)."
This category encompasses water secured outside of the TVMWD wholesale network. This includes wholesale purchases of treated surface water and groundwater from mutual water companies (such as the Covina Valley Water Company), purchases from neighboring municipalities (such as the City of Upland), and other external basin transfers utilized by agencies like Suburban Water Systems to serve their respective customers.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 32

3.2. Groundwater
Groundwater is a foundational component of the Region’s water supply portfolio, accounting for approximately 44 percent of the baseline water use (2021–2025 average). The Participating Agencies rely on local groundwater to meet baseload demands and to buffer against fluctuations in imported water availability during dry years.

The Region overlies a complex network of groundwater basins, each with distinct hydrogeological characteristics, recharge capabilities, and legal frameworks. The local groundwater supply utilized by the agencies within the TVMWD service area is primarily drawn from four basins that underlie the Region:
the Main San Gabriel Basin, the Chino Basin, the Six Basins, and the Spadra Basin. Additionally, agencies and joint powers authorities operating within the TVMWD service area hold adjudicated groundwater rights in two supplemental basins – the Central Basin and the Puente Basin – which are hydrologically connected to the Region's primary basins but lie partially or wholly south of the TVMWD service area boundary. Figure 3-1 summarizes the groundwater basins in the Region. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 33

Figure 3-1. TVMWD Regional Groundwater Basins

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 34

Groundwater extraction within the Region is highly regulated. The Main San Gabriel, Chino, Six Basins, Central, and Puente Basins are adjudicated, meaning that groundwater rights, safe yields, and recharge obligations are governed by court judgments and managed by court-appointed Watermasters or administrative bodies. Because they are adjudicated, these basins are exempt from the requirement to develop a Groundwater Sustainability Plan (GSP) under the Sustainable Groundwater Management Act (SGMA). The Spadra Basin is the only non-adjudicated basin utilized by the Region and is managed locally in compliance with SGMA.

While TVMWD acts primarily as a wholesale importer and only directly produces a small amount of groundwater from the Six Basins, it plays a vital role in regional groundwater sustainability. TVMWD delivers untreated imported water to replenish these local aquifers and maintains significant cyclic storage accounts to ensure water is available during extended droughts.

The physical characteristics, management structures, TVMWD’s and the Participating Agencies’ specific involvement in each of these basins are detailed in the following subsections.

3.2.1. Main San Gabriel Basin
The Main San Gabriel Basin (DWR Basin No. 4-013) is the primary groundwater basin of the Region's local supply, providing approximately 64 percent of the total regional groundwater utilized by agencies within the TVMWD service area. Within the context of this RUWMP, it primarily serves the western portion of the Region, including the City of Glendora, Golden State Water Company (San Dimas), and several Other Member Agencies such as Suburban Water Systems and the City of Covina.

Physical Characteristics and Hydrogeology
The Main San Gabriel Basin lies in eastern Los Angeles County and encompasses a surface area of approximately 167 square miles. The basin is bounded by the San Gabriel Mountains to the north, the Raymond fault to the northwest, the Repetto, Monterey, and Puente Hills to the south and southwest, and the San Jose fault to the east.

The basin's water-bearing formations consist of highly permeable alluvial deposits of sand, gravel, and silt. The basin is primarily drained by the San Gabriel River and the Rio Hondo. Dominant recharge to the sub-basin comes from the percolation of precipitation, infiltration of runoff from the San Gabriel Mountains, and the artificial recharge of imported water and recycled water at spreading grounds operated by the Los Angeles County Department of Public Works. Because of the basin's high permeability, it responds rapidly to both extraction and recharge events, making it an ideal basin for large-scale conjunctive use and water banking. Table 3-3 summarizes the aggregated historical groundwater production from the Main San Gabriel Basin by retail agencies within the TVMWD service area over the 2021–2025 baseline period.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 35

Table 3-3. Historical Groundwater Production from the Main San Gabriel Basin by TVMWD Agencies (AFY)
Water Source / Agency 2021 2022 2023 2024 2025 5-Year
Average
Participating Agencies 12,483 11,055 9,022 9,951 12,645 11,214 Other TVMWD Agencies* 29,120 28,961 28,568 29,005 28,940 28,919 Regional Total 41,603 40,016 37,590 38,956 41,046 40,133 *Note: To accurately reflect the total regional reliance on the Main San Gabriel Basin, this table incorporates estimated groundwater production for Other Member Agencies within the TVMWD service area. Because these agencies are not formal signatories to this 2025 RUWMP, their historical production volumes were estimated utilizing the best available public data, including 2020 UWMPs and recent Main San Gabriel Basin Watermaster Annual Reports.

Adjudication and Basin Management
The Main San Gabriel Basin was adjudicated in 1973 (Upper San Gabriel Valley MWD v. City of Alhambra). The Judgment (included in Part 3, Appendix K) established the Main San Gabriel Basin Watermaster to manage the basin and defined the prescriptive pumping rights of the overlying producers.

Instead of a fixed safe yield, the Watermaster manages the basin through an Operating Safe Yield (OSY), which is determined annually based on groundwater elevations, rainfall, and anticipated imported water availability. Historical OSYs for the Main San Gabriel Basin are shown in Table 3-4.

Table 3-4. Historical and Projected Operating Safe Yield of the Main San Gabriel Basin Fiscal Year(s) Operating Safe Yield (AF)
2010-2011 170,000
2012 210,000
2013 200,000
2014 180,000
2015-2024 150,000
2025-2026 160,000
2027-2030* 140,000
*Note: Projected OSYs are from Main San Gabriel Basin Watermaster Report on Final Determination of Operating Safe Yield for 2025-26 Through 2029-30 (Main San Gabriel Basin Watermaster, 2025) Pumping rights for each producer are calculated as a percentage of the OSY. However, extractions are not limited to a producer’s pumping rights. If a producer extracts water in excess of their right, they incur a "Replacement Water" assessment. The Watermaster uses these assessments to purchase untreated imported water to recharge the basin, thereby ensuring long-term sustainability and preventing overdraft.

Additionally, the Main San Gabriel Basin Watermaster annually adopts a Five-Year Water Quality and Supply Plan (included in Part 3, Appendix K) to proactively manage the basin’s groundwater quality and coordinate the delivery of Replacement Water (Main San Gabriel Watermaster, 2023). Because the Main San Gabriel Basin contains multiple EPA Superfund sites and areas impacted by legacy contaminants 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 36

(such as VOCs, PFAS, and nitrates), this Five-Year Water Quality and Supply Plan serves as a critical regulatory and reliability tool. It outlines the strategic funding and deployment of wellhead treatment facilities to prevent the migration of contaminant plumes. By treating contaminated groundwater and aggressively managing recharge, the Watermaster prevents wells from becoming "stranded," thereby safeguarding the basin's OSY and preventing unexpected, emergency spikes in demand for TVMWD's imported water during droughts.

Projected Supply Methodology
Because the OSY is determined annually by the Watermaster based on real-time hydrological conditions, reservoir storage, and groundwater elevations, this RUWMP does not attempt to forecast a firm administrative OSY out to the year 2050. Instead, to ensure this aggregated regional projection is realistic, TVMWD and the Participating Agencies compared the anticipated future groundwater extractions against the recent historical range of the basin's OSY.

Future local groundwater supplies from the Main San Gabriel Basin were developed using a bottom-up, agency-specific approach. For the Participating Agencies, the TVMWD Climate Assessment’s groundwater climate factors (discussed in Section 2.5.2) for 2030-2050 were applied directly to each agency's individual 2021-2025 actual average pumping baseline (TVMWD, 2024a). For the Other Member Agencies, Main San Gabriel Basin extractions were estimated utilizing the best available public data, as shown in Table 3-5. These individual projections were then aggregated to determine the total regional Main San Gabriel Basin supply through 2050.

Based on this bottom-up aggregation, regional extractions from the Main San Gabriel Basin are projected to range from 40,886 AF in 2030, gradually decreasing to 40,102 AF by 2050. Because these projected extractions fall below the Region's historical five-year average (41,046 AFY) during the basin's most restrictive recent historical OSYs (150,000-160,000 AF), this analysis confirms that the projected extractions remain highly plausible and can be sustainably managed through the Watermaster's existing Replacement Water assessment framework.

TVMWD's Role and Storage Programs
As a regional wholesaler, TVMWD is a critical partner in the management of the Main San Gabriel Basin.

TVMWD delivers untreated imported water from MWD to the basin's spreading grounds to satisfy the Replacement Water obligations of the pumpers located within TVMWD's service area.

To capture additional imported supplies during wet years when MWD water is abundant, TVMWD participates in a Cyclic Storage Program within the basin. The Cyclic Storage Agreement between MWD, TVMWD, and the Watermaster (included in Part 3, Appendix K) allows for the pre-delivery and storage of up to 50,000 AF of imported water. This agreement, originally signed in 1991, was recently amended effective June 2024 to extend the termination date to June 2034. TVMWD had approximately 3,079 AF stored in the basin as of the end of 2025.

Additionally, the Puente Basin Water Agency (PBWA) – a joint powers authority between Rowland Water District and Walnut Valley Water District – maintains a storage and export agreement with the 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 37

Main San Gabriel Basin for 30,000 AF (included in Part 3, Appendix K). This banking arrangement allows PBWA to purchase surplus imported water or local supplies when available, bank them in the Main San Gabriel Basin, and subsequently extract and export that water to the Rowland and Walnut Valley service areas during dry years or periods of imported supply constraint. This provides a critical local buffer for these two retail agencies, which are historically highly dependent on imported water.

Table 3-5 summarizes the current regional storage agreements and capacities within the Main San Gabriel Basin.

Table 3-5. TVMWD Storage and Export Agreements in the Main San Gabriel Basin Agreement / Account Type Managing Entities Maximum Storage Capacity (AF)
Estimated Stored Balance
(End of 2025) (AF)
Cyclic Storage Agreement TVMWD, MWD, Main
Basin Watermaster
50,000 3,079
Storage and Export Agreement PBWA 30,000 3,0001

1. Balance estimated based on the PBWA Board of Commissioners' October 2024 authorization to purchase 3,000 AF of cyclic storage for the 2025-2029 water years (PBWA, 2024).

3.2.2. Chino Basin
The Chino Basin (DWR Basin No. 8-02.01) provides approximately 17 percent of the total regional groundwater utilized by agencies within the TVMWD service area. Within the context of this RUWMP, extraction from the Chino Basin is predominantly utilized by the City of Pomona to serve the eastern portion of the Region.

Physical Characteristics and Hydrogeology
The Chino Basin is a large groundwater basin located in the southwest corner of San Bernardino County and the northwest corner of Riverside County. The basin is bordered by the San Gabriel Mountains to the north, the Rialto-Colton fault to the east, and the Jurupa Mountains and Puente Hills to the south and southwest. The surface area of the Chino Basin is approximately 154,000 acres (or 240 square miles). The San Antonio Creek and Cucamonga Creek drain the Chino Basin area southward and flow into the Santa Ana River. The Chino Basin is a subbasin of the Upper Santa Ana Valley Groundwater Basin and has a total storage capacity of approximately 5,000,000 AF.

The basin consists of highly permeable alluvial deposits. Surface drainage in this portion of the region flows generally southward via San Antonio Creek and Chino Creek toward the Santa Ana River. The principal sources of natural recharge are percolation of precipitation and infiltration of runoff from the San Gabriel Mountains. This is supplemented by significant artificial recharge of imported water and recycled water managed by regional partners.

Adjudication and Basin Management
The Chino Basin was adjudicated in 1978 (Chino Basin Municipal Water District v. City of Chino et al.) (included in Part 3, Appendix L). The Judgment established the Chino Basin Watermaster to account for 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 38

and implement the management of the basin, and it contains a physical solution to meet the requirements of all water users.

The Chino Basin Judgment originally established a Safe Yield for the Chino Basin of 140,000 AFY. The Safe Yield is typically recalculated every 10 years and is defined in the Chino Basin Judgment as “the long-term average annual quantity of ground water (excluding replenishment of stored water but including return flow to the Basin from use of replenishment or stored water) which can be produced from the Chino Basin under conditions of a particular year without causing an undesirable result”.

Pursuant to the most recent Safe Yield reset effective in 2020, the Safe Yield for the Chino Basin is currently 131,000 AFY (effective from July 1, 2020 to June 30, 2030).

In April 2017, a Court Order regarding the Safe Yield of the Chino Basin (San Bernardino County Superior Court, 2017) was issued, which caused the Safe Yield to be recalculated in 2025. The 2017 Safe Yield Court Order also required changes to the Safe Yield Reset methodology. The methodology was updated in 2022, and the 2025 Safe Yield Reset process began in 2023. The 2025 Safe Yield Reset is not yet final, so for purposes of this UWMP, the Safe Yield for the Chino Basin is based on the currently effective value of 131,000 AFY. Additional information on the 2025 Safe Yield Reset is available on the Chino Basin Watermaster website (https://www.cbwm.org/pages/syrm/).

The Chino Basin Judgment’s allocation of the Safe Yield includes three separate pools:

1. Overlying Agricultural Pool (farmers, State of California, and other minimal producers)

2. Overlying Non-Agricultural Pool (businesses and industries)

3. Appropriative Pool (cities, agencies, and other water suppliers, including Ontario) As of July 2020, the Safe Yield is allocated among these three pools at 82,800 AFY to the Overlying Agricultural Pool, 7,366 AFY to the Overlying Non-Agricultural Pool, and 40,834 AFY to the Appropriative Pool.

Appropriators who are Parties to the Chino Basin Judgment are authorized to produce groundwater in excess of their rights. For any groundwater produced in excess of their rights, Appropriators pay assessments to the Chino Basin Watermaster, which are used to purchase water to replenish the Chino Basin. The Chino Basin Watermaster purchases water from MWD through IEUA and/or TVMWD, on behalf of the Parties, to replenish the Chino Basin. Occasionally, Watermaster has purchased water from storage accounts from parties within the Chino Basin.

In addition to the water rights described above, the Judgment provides for additional provisions to allocate the Chino Basin water as described below:

Land Use Conversion
When land is converted from agricultural to urban use, water rights are permanently transferred from the Overlying Agricultural Pool to the Appropriative Pool. Land use conversions assign the increase in Appropriative Pool rights to the party whose sphere of influence includes the converted land. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 39

Annual Unused Overlying Agricultural Pool Rights
The Chino Basin Watermaster also reallocates the unused portion of the Chino Basin Safe Yield from the Overlying Agricultural Pool to the Appropriative Pool members’ rights in any year. These transfers are permanent if agricultural land has been converted to non-agricultural use (described above), or temporary if agricultural pool extractions are less than their share of the Safe Yield. From FY20/21 to FY24/25, 9,000 AFY of rights have been reallocated from the Overlying Agricultural pool to the Appropriative Pool that were not claimed as part of a permanent land conversion.

Today, the basin is comprehensively managed through the implementation of the Optimum Basin Management Program (OBMP) (included in Part 3, Appendix L), which was originally developed in 2000 and updated in 2020 (Chino Basin Watermaster, 2020). The OBMP functions similarly to a GSP under SGMA, featuring robust monitoring, subsidence management, and coordinated recharge programs to ensure long-term sustainability.

Chino Basin Storage Management Plan
The Peace Agreement (2000) (included in Part 3, Appendix L) establishes rules and regulations, standard storage agreements, and related forms for storage in the Chino Basin. Since 2000, Chino Basin Watermaster administers groundwater storage in the Chino Basin pursuant to the storage management plan described in the 2000 OBMP.

There are five types of storage accounts: Excess Carryover, Local Supplemental-Recycled, Local Supplemental-Imported, Pre-2000 Quantified Supplemental, and Storage and Recovery. ⚫ Excess Carryover Account – includes a Party’s unproduced rights in the Safe Yield (Safe Yield for Overlying Non-Agricultural Pool Parties and OSY for Appropriative Pool Parties) and Basin Water purchased or transferred from other Parties.
⚫ Local Supplemental-Recycled Account– includes recycled water that is recharged by a producer and similar water acquired from other Parties.
⚫ Local Supplemental-Imported Account– includes imported water that is recharged by a producer and similar water acquired from other Parties.
⚫ Pre-2000 Quantified Supplemental Account – functions similar to Local Supplemental Water Account.
⚫ Storage and Recovery Account – holds Supplemental Water (imported or recycled) and is intended to provide a broad and mutual benefit to the Parties of the Judgment.

Dry Year Yield Program
MWD’s Dry-Year Yield Program (DYYP) is the only active Storage and Recovery Program in Chino Basin.

This program is a water exchange as discussed in Section 3.7.1.

Table 3-6 summarizes the aggregated historical groundwater production from the Chino Basin by retail agencies within the TVMWD service area over the 2021–2025 baseline period. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 40

Table 3-6. Historical Groundwater Production from the Chino Basin by TVMWD Agencies (AFY) Water Source / Agency 2021 2022 2023 2024 2025 5-Year
Average
Participating Agencies 10,255 11,222 11,111 11,440 10,734 10,952 Other TVMWD Agencies 0 0 0 0 0 0
Regional Total 10,255 11,222 11,111 11,440 10,734 10,952 Projected Supply Methodology
Utilizing the same bottom-up, climate-scaled methodology described for the Main San Gabriel Basin (see Section 3.2.1), future local groundwater supplies from the Chino Basin were projected through 2050.

This approach ensures regional consistency while aligning with the management criteria established by the Chino Basin Watermaster.

Based on this regional aggregation, extractions from the Chino Basin by agencies within the TVMWD service area are projected to range from 11,053 AF in 2030, gradually decreasing to 10,204 AF by 2050.

While the near-term projected extraction (11,053 AF) represents a slight increase over the 2021–2025 historical baseline average (10,952 AFY), these extractions remain consistent with the agencies’ historically exercised rights within the basin’s Appropriative Pool. As described above, because the Chino Basin is strictly adjudicated, all extractions – by TVMWD agencies and the numerous other overlying and appropriative purveyors sharing the basin's 131,000 AF Operating Safe Yield – are comprehensively tracked by the Watermaster. Any pumping that exceeds an individual agency's specific allocated share is mitigated through mandatory replenishment assessments used to purchase imported recharge water. Therefore, this analysis confirms that the projected extractions by TVMWD agencies are plausible and can be sustainably managed within the Optimum Basin Management Program (OBMP) framework.

TVMWD's Role and Storage Programs
Because the Chino Basin largely falls outside of TVMWD’s primary wholesale service boundaries, TVMWD’s interaction with the basin is facilitated through partnerships with its member agencies, primarily the City of Pomona (included in Part 3, Appendix L). Currently, TVMWD holds a storage account of 1,390 AF in the Chino Basin through a one-time agreement with the City of Pomona.

Table 3-7 summarizes TVMWD's current storage capacity within the Chino Basin.

Table 3-7. TVMWD Storage Agreements in the Chino Basin
Agreement / Account Type Managing Entities Maximum Storage Capacity (AF)
Estimated Stored Balance
(End of 2025) (AF)
One-Time Storage
Agreement
TVMWD, City of Pomona 1,390 1,390

3.2.3. Six Basins
The Six Basins area provides approximately 13 percent of the total regional groundwater utilized by agencies within the TVMWD service area. Within the context of this RUWMP, it is a vital local supply 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 41

source for the City of Pomona, the City of La Verne, Golden State Water Company (Claremont system), and uniquely, TVMWD itself, which directly extracts groundwater from this basin to supplement its wholesale portfolio.

Physical Characteristics and Hydrogeology
Located along the base of the San Gabriel Mountains, the Six Basins area overlies a portion of the eastern San Gabriel Valley in Los Angeles County and western San Bernardino County. The area is bounded by the San Gabriel Mountains to the north, the San Jose Hills to the south, the Main San Gabriel Basin to the west, and the Chino Basin to the east.

As the name implies, the area consists of six interconnected groundwater sub-basins: Canyon Basin, Upper Claremont Heights Basin, Lower Claremont Heights Basin, Pomona Basin, Live Oak Basin, and Ganesha Basin. The primary source of natural groundwater replenishment is surface-water runoff from precipitation falling on the San Gabriel Mountains, which infiltrates through highly permeable sediments, predominantly at the San Antonio Spreading Grounds. Table 3-8 summarizes the aggregated historical groundwater production from the Six Basins by retail agencies within the TVMWD service area over the 2021–2025 baseline period.

Table 3-8. Historical Groundwater Production from the Six Basins by TVMWD Agencies (AFY) Water Source / Agency 2021 2022 2023 2024 2025 5-Year Average Participating Agencies 9,581 8,728 6,682 7,629 9,597 8,444 Other TVMWD Agencies 0 0 0 0 0 0
Regional Total 9,581 8,728 6,682 7,629 9,597 8,444
Adjudication and Basin Management
The pumping and storage rights for the Six Basins were adjudicated in 1998 (Southern California Water Company vs. City of La Verne, et al., Case No. KC029152). The Judgment (included in Part 3, Appendix M) established the Six Basins Watermaster to oversee the physical solution and coordinated management of the interconnected basins.

Pursuant to the Judgment, the statutory safe yield of the Six Basins is 19,300 AFY, defined as the amount of water that can be produced by the parties on an annual basis to ensure long-term, sustainable groundwater production. For management purposes, the Judgment divides the Six Basins into two distinct operational areas. The production, replenishment, and recovery of the Live Oak and Ganesha Basins (collectively referred to as the "Two Basins") are reserved solely for the City of La Verne and are not subject to groundwater production limitations, provided that La Verne's production does not substantially injure the rights of any other Six Basin parties.

Conversely, the Canyon, Upper Claremont Heights, Lower Claremont Heights, and Pomona Basins (collectively referred to as the "Four Basins") are managed using an OSY rather than a static safe yield.

The Watermaster annually determines the OSY based on current groundwater elevations, precipitation, and recharge capabilities to ensure the parties can reliably pump their respective rights while preventing 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 42

overdraft and mitigating the risk of high groundwater damaging shallow infrastructure during wet periods. Table 3-9 summarizes the recent OSY determinations for the Four Basins.

Table 3-9. Recent Operating Safe Yields (Four Basins)
Calendar Year Operating Safe Yield (AF)
2011-2013 17,500
2014 16,500
2015-2016 16,000
2017 14,000
2018 13,500
2019-2023 13,000
2024 13,500
2025 14,000
Pumping rights for each producer in the Four Basins are allocated based on the annual OSY. To provide operational flexibility, the Judgment allows producers to carry over a portion of their unused annual pumping rights (up to a maximum of 25% of their share of the OSY) into the following year.

Furthermore, extractions are not strictly limited to a producer’s base pumping right. If a producer extracts water in excess of their right, that excess amount is either deducted from their following year’s water rights or they incur a replacement water assessment. The Watermaster utilizes these assessments to purchase supplemental water (such as untreated imported water from TVMWD) to recharge the basin, thereby ensuring long-term sustainability, providing year-to-year flexibility for the pumpers, and preventing overdraft.

Additionally, the Six Basins Watermaster actively manages the basin’s groundwater quality and coordinates recharge efforts through its comprehensive Strategic Plan (included in Part 3, Appendix M) and ongoing Watermaster management initiatives. Because portions of the Six Basins face localized water quality challenges (such as nitrate and VOC accumulation, particularly in the Pomona Basin), these management strategies serve as critical regulatory and reliability tools. They guide the strategic funding and deployment of wellhead treatment and blending facilities to prevent the migration of contaminant plumes. By treating contaminated groundwater and aggressively managing stormwater and imported water recharge at facilities like the San Antonio Spreading Grounds, the Watermaster prevents wells from becoming "stranded." This safeguards the basin's OSY and prevents unexpected, emergency spikes in demand for TVMWD's imported water during droughts.

Projected Supply Methodology
Utilizing the same bottom-up, climate-scaled methodology described for the Main San Gabriel Basin (see Section 3.2.1), future local groundwater supplies from the Six Basins were projected through 2050.

Based on this bottom-up aggregation, regional extractions from the Six Basins are projected to range from 9,355 in 2030, gradually decreasing to 8,811 by 2050. While these projected volumes represent a slight increase over the 2021–2025 historical average (8,438 AFY), they remain conservative and sustainable. The maximum projected extraction of 9,355 AF is less than half of the basin's adjudicated Base Safe Yield (19,300 AF) and remains well below the Watermaster's most restrictive recent drought 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 43

OSY (13,000 AF, in 2021). Therefore, this analysis confirms that the projected extractions are plausible and can be sustainably managed within the Watermaster's existing framework.

TVMWD's Role and Storage Programs
TVMWD’s relationship with the Six Basins is unique among the region's groundwater sources because TVMWD acts as both a replenisher and a direct producer. TVMWD owns and operates three active groundwater extraction wells located in the Six Basins. The raw groundwater produced from these wells is conveyed to TVMWD’s MWTP, where it is treated and blended with imported supplies before being distributed to member agencies.

To support dry-year reliability, TVMWD holds a direct operational storage account in the Six Basins with a capacity of 3,500 AF (included in Part 3, Appendix M). Table 3-10 summarizes TVMWD's current storage capacity within the Six Basins. TVMWD actively supports the replenishment of the basin by delivering untreated imported water to the San Antonio Spreading Grounds, occasionally utilizing interconnections like the City of Pomona’s Canon pipeline to maximize surface water capture and recharge.

Table 3-10. TVMWD Storage Agreements in the Six Basins
Agreement / Account
Type
Managing Entities Maximum Storage
Capacity (AF)
Estimated Stored Balance
(End of 2025) (AF)
Operational Storage
Account
TVMWD, Six Basins
Watermaster
3,500 ~3,5001

1. Based on 2024 Annual Watermaster Report (Six Basins Watermaster, 2025). Final 2025 stored balances are subject to ongoing Six Basins Watermaster reconciliation.

3.2.4. Spadra Basin
While smaller in volume than the other regional basins, the Spadra Basin provides a localized and highly valuable groundwater supply for the southeastern portion of the Region. Because groundwater produced from this basin often requires treatment or blending to comply with SWRCB-DDW drinking water standards, it is currently utilized primarily to meet non-potable overlying demands. Within the context of this RUWMP, extractions from the Spadra Basin are utilized primarily by the WVWD, the City of Pomona, and Cal Poly Pomona.

Physical Characteristics and Hydrogeology
The Spadra Basin is a small sub-basin of the larger San Gabriel Valley Groundwater Basin. It is located within the San Jose Creek valley in eastern Los Angeles County. The basin is distinctly bounded by the San Jose Hills to the north and northwest, and the Puente Hills to the south and southwest.

The basin's hydrogeology consists of alluvial deposits from surrounding highlands, with San Jose Creek serving as the primary surface drainage feature flowing westward toward the San Gabriel River. Natural recharge occurs primarily through the percolation of precipitation and surface water runoff from the San Jose Hills and Puente Hills, as well as infiltration from San Jose Creek. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 44

SGMA Compliance and Basin Management
Unlike the Main San Gabriel, Chino, and Six Basins, the Spadra Basin is not adjudicated. Therefore, it is subject to the requirements of SGMA.

DWR has designated the Spadra Basin as a "very low-priority" basin. Under SGMA, very low-priority basins are not legally required to form a Groundwater Sustainability Agency (GSA) or adopt a GSP.

However, recognizing the strategic importance of this local supply, WVWD and the City of Pomona proactively entered into a Memorandum of Agreement (included in Part 3, Appendix N) to collectively form the Spadra Basin GSA. The GSA has developed a GSP (included in Part 3, Appendix N) to comprehensively manage the basin, monitor water quality, and ensure sustainable extractions that prevent chronic lowering of groundwater levels.

Instead of an OSY determined by a Watermaster, the GSP establishes a long-term "Sustainable Yield" for the basin, which is currently estimated at approximately 1,050 AFY (Spadra Basin GSA, 2022). To ensure extractions remain within sustainable limits, the GSP defines specific Sustainable Management Criteria, including Measurable Objectives (MOs) and Minimum Thresholds for groundwater elevations.

Sustainable management practices actively implemented by the GSA include:
⚫ Comprehensive Monitoring: Regular tracking of groundwater levels and water quality to ensure the basin operates within its established MOs and avoids "Undesirable Results" (such as the chronic lowering of groundwater levels or degraded water quality). ⚫ Recharge Optimization: As detailed in Section 3.9, the GSA agencies are actively pursuing the Spadra Basin Optimization Project. By utilizing advanced treated recycled water for underground injection, the GSA aims to physically bolster the basin's Sustainable Yield and increase local extraction capacity without causing overdraft.
⚫ Water Quality Management: Collaborating with basin producers (such as Cal Poly Pomona) to implement wellhead treatment for localized VOCs, ensuring existing wells remain operational and do not become stranded assets.

Table 3-11 summarizes the aggregated historical groundwater production from the Spadra Basin by agencies within the TVMWD service area over the 2021–2025 baseline period.

Table 3-11. Historical Groundwater Production from the Spadra Basin by TVMWD Agencies (AFY) Water Source /Agency 2021 2022 2023 2024 2025 5-Year Average Participating Agencies 0 0 0 0 0 0
Other TVMWD Agencies* 704 704 704 704 704 704
Regional Total 704 704 704 704 704 704
*Note: To accurately reflect the total regional reliance on the Spadra Basin, this table incorporates estimated groundwater production for Other Member Agencies within the TVMWD service area. Because these agencies are not formal signatories to this 2025 RUWMP, their historical production volumes were estimated utilizing the best available public data, including related environmental documentation and the Spadra Basin GSP.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 45

Projected Supply Methodology
Utilizing the same bottom-up, climate-scaled methodology described for the Main San Gabriel Basin (see Section 3.2.1), future local groundwater supplies from the Spadra Basin were projected through 2050.

This approach ensures regional consistency while adhering to the management criteria established in the Spadra Basin GSP.

Based on this regional aggregation, extractions from the Spadra Basin are projected to remain consistent at 856 AF in 2030 through 2050. Because these projected volumes align closely with the 2021–2025 historical average (704 AFY) and remain below the basin's estimated Sustainable Yield (approximately 1,050 AFY), this analysis confirms that the projected extractions are plausible and can be sustainably managed within the Spadra Basin GSA's framework. Furthermore, to increase the margin of safety and protect against climate volatility, the GSA agencies are advancing the Spadra Basin Optimization Project (detailed in Section 3.9) to inject recycled water and significantly expand the basin's sustainable yield threshold.

TVMWD's Role and Planned Storage Programs
Currently, TVMWD does not hold an active operational storage account in the Spadra Basin. However, expanding the use of the Spadra Basin is a key component of the Region's future mitigation and reliability strategy.

3.2.5. Central Basin
The Central Basin (DWR Basin No. 4-011.04) is a large adjudicated groundwater basin located in the Coastal Plain of Los Angeles, immediately south and southwest of the TVMWD service area. While the Central Basin is not a primary local supply source for the Region, it is included in this RUWMP because it is hydrologically connected to the TVMWD service area through the Main San Gabriel Basin and because two entities operating within the TVMWD service area – Suburban Water Systems and PBWA – hold adjudicated pumping rights within the basin. Within the context of this RUWMP, groundwater extraction from the Central Basin is utilized exclusively by Suburban Water Systems to serve the southwestern portion of its service area, providing approximately 3 percent of the total regional groundwater utilized by agencies within the TVMWD service area.

Physical Characteristics and Hydrogeology
The Central Basin is one of the largest groundwater basins in Los Angeles County, encompassing a surface area of approximately 277 square miles. The basin is a subbasin of the larger Coastal Plain of Los Angeles Groundwater Basin and is bounded on the northeast and east by the Elysian, Repetto, Merced, and Puente Hills, on the southeast by the Los Angeles County–Orange County line (roughly following Coyote Creek), and on the south and west by the Newport-Inglewood fault system and its associated uplift. The Los Angeles River and San Gabriel River drain across the surface of the Central Basin on their way to the Pacific Ocean.

The California Department of Water Resources historically divided the Central Basin into four hydrogeologic divisions: the Los Angeles Forebay, the Montebello Forebay, the Whittier Area, and the 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 46

Central Basin Pressure Area. The two forebays contain unconfined aquifers with relatively interconnected water-bearing strata extending up to 1,600 feet deep, providing the primary pathways for recharge to the deeper aquifer system. The Whittier Area and Pressure Area are predominantly confined aquifer systems consisting of permeable sands and gravels separated by semi-permeable to impermeable clay layers extending to approximately 2,200 feet below the surface. The principal water- producing formations are the Lakewood Formation and the San Pedro Formation. Total storage capacity of the basin is estimated to be approximately 13.8 million AF.

The hydrologic connection between the Central Basin and the TVMWD service area is significant: the Montebello Forebay receives both surface and subsurface inflow from the Main San Gabriel Basin through a gap in the Merced and Puente Hills at Whittier Narrows. This gap provides the primary conduit through which outflows from the TVMWD region's largest groundwater basin – including the replenishment water delivered by TVMWD to the Main San Gabriel Basin's spreading grounds – ultimately reach and recharge the Central Basin.

Adjudication and Basin Management
The Central Basin was adjudicated in 1965 (Central and West Basin Water Replenishment District v.

Charles E. Adams et al.). The original Judgment was entered on October 11, 1965, and appointed DWR as Watermaster. The Judgment has been amended three times since its inception: the First Amended Judgment (1980) transitioned the administrative year from a water year to a fiscal year basis (July 1 through June 30); the Second Amended Judgment (1991) modified carryover and overproduction provisions; and, most significantly, the Third Amended Judgment was entered on December 23, 2013, substantially modernizing basin governance and establishing provisions for groundwater storage (Third Amended Judgment included in Part 3, Appendix T.

Under the Third Amended Judgment, the Central Basin Watermaster is composed of three separate bodies with distinct responsibilities:
⚫ The Administrative Body: WRD serves as the court-appointed Administrative Body, responsible for the administration and enforcement of the Judgment, including accounting and reporting functions related to groundwater extractions, carryover, and storage. ⚫ The Water Rights Panel: Composed of seven Central Basin water rights holders, the Panel has exclusive authority to enforce adjudicated extraction rights and manage the Exchange Pool. ⚫ The Storage Panel: Composed of the Water Rights Panel and the WRD Board of Directors, the Panel reviews and approves groundwater storage projects within the basin.

Unlike the Main San Gabriel and Six Basins, which utilize an annually determined OSY that fluctuates based on real-time hydrological conditions, the Central Basin operates under fixed Allowed Pumping Allocations (APAs). Each party's APA represents 80 percent of its court-adjudicated Total Water Right.

Parties are permitted to carry over unused pumping rights (up to 60 percent of their APA) into the following administrative year and may extract up to 140 percent of the sum of their APA and leased water in any given year, provided they have sufficient carryover or stored water balances. Over- 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 47

extractions by parties without stored water are limited to the greater of 20 percent of their APA or 20 AF.

The Third Amended Judgment also established formal provisions for groundwater storage in the Central Basin for the first time, designating an Adjudicated Storage Capacity of 220,000 AF. This storage capacity is apportioned between Individual Storage Accounts – sized at 50 percent of each party's APA – and a Community Storage Pool available on a first-come, first-served basis. Additionally, the Judgment established the Regional Disadvantaged Communities Incentive Program, which reserves up to 23,000 AF of the Community Storage Pool for the use or benefit of DACs within the Central Basin.

Groundwater replenishment in the Central Basin is managed by the Water Replenishment District of Southern California (WRD), which purchases imported water from MWD and recycled water from the Los Angeles County Sanitation Districts (LACSD) for recharge at the Montebello Forebay spreading grounds. WRD also manages the Alamitos Gap, Dominguez Gap, and West Coast Basin Barrier injection well projects to prevent seawater intrusion into the basin's coastal aquifers.

Table 3-12 summarizes the aggregated historical groundwater production from the Central Basin by retail agencies within the TVMWD service area over the 2021–2025 baseline period.

Table 3-12. Historical Groundwater Production from the Central Basin by TVMWD Agencies (AFY) Water Source / Agency 2021 2022 2023 2024 2025 5-Year Average Participating Agencies 0 0 0 0 0 0
Other TVMWD Agencies* 1,543 1,151 1,118 2,253 2,728 1,759 Regional Total 1,543 1,151 1,118 2,253 2,728 1,759
*Note: To accurately reflect the total regional reliance on the Spadra Basin, this table incorporates estimated groundwater production for Other Member Agencies within the TVMWD service area. Because these agencies are not formal signatories to this 2025 RUWMP, their historical production volumes were estimated utilizing the best available public data, including Central Basin Watermaster Annual Reports published by WRD.

3.2.6. Puente Basin
The Puente Basin is a small, adjudicated groundwater basin located in eastern Los Angeles County, directly beneath the southern portion of the TVMWD service area. Unlike the Central Basin described in the preceding section, the Puente Basin lies entirely within the Region's geographic footprint and is actively managed by the PBWA. Groundwater within the Puente Basin is currently utilized exclusively for non-potable purposes, primarily recycled water distribution blending by Rowland Water District. While extraction volumes are small relative to the Region's other basins (approximately 1 percent of the total regional groundwater), the Puente Basin represents a strategically important local resource that PBWA is actively working to develop through a comprehensive Groundwater Management Plan.

Physical Characteristics and Hydrogeology
The Puente Basin spans approximately 20 square miles and is situated in a narrow alluvial valley between the San Jose Hills to the north and the Puente Hills to the south. The basin shares its eastern boundary with the Spadra Basin (described in Section 3.2.4) and its western boundary with the Main San 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 48

Gabriel Basin (described in Section 3.2.1). San Jose Creek, the basin's primary surface drainage feature, flows through the basin from northeast to west, ultimately passing through Whittier Narrows into the Central Basin (described in Section 3.2.5).

The basin's water-bearing formations consist of alluvial deposits along the San Jose Creek valley. Natural recharge occurs primarily through the percolation of precipitation and infiltration of surface water runoff from the surrounding San Jose Hills and Puente Hills. The basin also receives subsurface inflow from the adjacent Spadra Basin to the east.

Three water districts overlie the Puente Basin boundary: Walnut Valley WD, Rowland WD, and the Upper San Gabriel Valley Municipal Water District. The basin is sandwiched between the TVMWD service area's other groundwater resources and lies along the path of San Jose Creek's westward flow, making it a critical hydrologic link in the broader regional groundwater system. The Puente Narrows Agreement, established in connection with the 1973 Main San Gabriel Basin adjudication, governs subsurface outflow from the Puente Basin into the Main San Gabriel Basin, and the 1965 Long Beach Judgment guarantees the Central and West Coast Basins an average annual water supply through Whittier Narrows that includes underflow from the Puente Basin.

Adjudication and Basin Management
The Puente Basin was adjudicated in 1985. The Judgment (included in Part 3, Appendix U) established the legal framework for groundwater extraction rights within the basin and recognized the basin's hydrologic connections to the adjacent Main San Gabriel and Central Basins through the Puente Narrows Agreement (included in Part 3, Appendix U.

Because the Puente Basin is adjudicated, it is exempt from the requirement to form a GSA or adopt a GSP under SGMA. Basin management is instead governed by the terms of the Judgment and administered through PBWA in coordination with the Upper San Gabriel Valley Municipal Water District.

Recognizing the strategic value of this local resource, PBWA is currently developing a voluntary Groundwater Management Plan (GMP) to guide the future management and beneficial use of the Puente Basin. As part of this effort, PBWA has completed several technical memoranda, including TM-1:

Conceptual Understanding of the Puente Basin (PBWA, 2023); TM-2: Goals and Concepts for Improved Basin Management memorandum (PBWA, 2024a); and TM-3: Basin Management Alternatives analysis (PBWA, 2025). PBWA has conducted stakeholder meetings throughout 2024 and 2025 to solicit input on the GMP's development, with the stated objective of maximizing the beneficial use of the basin in a conjunctive manner with the Region's other water resources — including imported water from TVMWD, treated recycled water from LACSD, and groundwater from adjacent basins.

Current Groundwater Use
Groundwater within the Puente Basin is currently impaired by water quality constraints that limit its use to non-potable applications. Rowland WD operates a well within the Puente Basin that produces impaired groundwater for blending into its recycled water distribution system. This groundwater, along with treated water captured from an EPA Superfund cleanup project and recycled water purchased from 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 49

LACSD (via the San Jose Creek Water Reclamation Plant), supports Rowland WD's extensive non-potable recycled water program.

3.2.7. Groundwater Quality Impacts on Reliability
Groundwater quality in the Region is generally sufficient to meet municipal demands, provided that appropriate wellhead treatment and blending strategies are employed. The Participating Agencies and local Watermasters continuously monitor groundwater quality in accordance with the State Water Resources Control Board (SWRCB) DDW regulations and the Groundwater Ambient Monitoring and Assessment (GAMA) Program.

While local groundwater is a highly reliable source in terms of volume, its usability is constrained by historical land-use practices. Decades of agricultural, industrial, and military activities have introduced various contaminants into the underlying aquifers of the Main San Gabriel, Chino, Six Basins, Spadra, Central, and Puente basins. When wells exhibit contaminant levels exceeding the Maximum Contaminant Levels (MCLs) or Notification Levels set by DDW, they must be removed from service until treatment is installed or blending plans are approved.

Primary Contaminants of Concern
Groundwater from the Region's basins has historically exhibited exceedances for several constituents.

The most prevalent contaminants requiring active management include:
⚫ Volatile Organic Compounds (VOCs): Chemicals such as Tetrachloroethene (PCE) and Trichloroethene (TCE) are widely present, primarily resulting from legacy industrial and aerospace manufacturing in the San Gabriel Valley.
⚫ Nitrates and Total Dissolved Solids: Elevated levels of nitrates and salts are particularly prevalent in the Chino Basin and portions of the Six Basins, stemming from historical agricultural operations, dairy farming, and the use of imported water and recycled water for recharge. ⚫ Perchlorate: A chemical used in rocket fuel and flares, perchlorate has impacted groundwater wells in several areas, requiring specialized ion-exchange treatment. ⚫ Contaminants of Emerging Concern (CECs) and PFAS: Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used in fire-retardant foams and consumer products. As DDW establishes strict new Public Health Goals and MCLs for PFAS (specifically PFOA and PFOS), many agencies in the Region are being forced to take wells offline and rapidly design and construct new GAC or ion-exchange treatment facilities.
⚫ Other Constituents: 1,2,3-Trichloropropane (1,2,3-TCP), Hexavalent Chromium, Arsenic, 1,2- Dibromo-3-chloropropane (DBCP), and naturally occurring Uranium.

Table 3-13 describes the primary groundwater contaminants of concern in the Region. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 50

Table 3-13. Primary Groundwater Contaminants and Regional Treatment Strategies Contaminant of
Concern
Primary Source / Cause Typical Treatment Technology
Utilized in Region
Impacted Basins
(General)
VOCs (PCE, TCE) Legacy industrial and
aerospace manufacturing
Granular Activated Carbon
(GAC), Air Stripping
Main San Gabriel,
Spadra, Six Basins
Nitrates Historical agriculture, dairy
farming, fertilizers
Blending, Anion Exchange,
Reverse Osmosis (RO)
Chino Basin, Six Basins
TDS (Salinity) Agricultural runoff,
imported/recycled water
recharge
Reverse Osmosis (Desalters) Chino Basin
Perchlorate Rocket propellants, flares,
explosives
Ion Exchange (IX) Main San Gabriel, Six
Basins
PFAS / PFOA Fire-fighting foams,
industrial consumer
products
Granular Activated Carbon
(GAC), Ion Exchange
Region-wide
1,2,3-TCP Legacy agricultural soil
fumigants
Granular Activated Carbon
(GAC)
Chino Basin, Six Basins
Known Contaminant Plumes and Basin-Specific Quality
The distribution of these contaminants varies by basin:

Main San Gabriel Basin: The EPA designated portions of the San Gabriel Valley as Superfund sites due to extensive VOC contamination. Major groundwater cleanup projects, such as the Baldwin Park Operable Unit (BPOU), utilize large-scale extraction and advanced treatment facilities to contain the migration of these plumes, remove VOCs and perchlorate, and provide treated water for municipal supply.

Chino Basin: The Chino Basin faces significant challenges with TDS and nitrates. The Chino Basin Watermaster's OBMP includes the operation of regional groundwater desalters to extract and treat this degraded water, preventing the migration of poor-quality water into cleaner areas of the basin and producing potable supply.

Six Basins and Spadra Basin: Localized VOC and nitrate contamination impacts wells in these basins.

Because groundwater produced from the Spadra Basin frequently requires extensive wellhead treatment or blending to comply with SWRCB-DDW drinking water standards, it is currently utilized primarily to meet non-potable overlying demands by local water agencies. To overcome these constraints and restore potable capacity, agencies are actively investing in remediation. For example, as noted in the TVMWD’s WRMP (TVMWD, 2025), Cal Poly Pomona is pursuing VOC treatment at its Well No. 2 within the Spadra Basin to restore its capacity to produce potable water.

Central Basin and Puente Basin: The Central Basin faces water quality challenges common to the greater Coastal Plain of Los Angeles, including localized saltwater intrusion along its coastal margins and legacy contamination from industrial activities. WRD manages basin-wide water quality monitoring and replenishment using recycled water and imported water. The Puente Basin contains impaired groundwater that currently limits extraction to non-potable uses by Rowland WD. PBWA is actively 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 51

evaluating wellhead treatment options through its ongoing Groundwater Management Plan development process to potentially restore potable extraction capacity in the future. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 52

Impact on Supply Reliability
Groundwater quality degradation has a direct and severe impact on the Region's water supply reliability.

When local wells are shut down due to contamination (referred to in the WRMP as "stranded assets"), retail agencies lose their ability to pump their adjudicated groundwater rights. To replace this lost local supply, agencies are forced to increase their purchases of imported water from TVMWD. This dynamic shifts the burden to the imported water system, precisely when the Region is attempting to reduce its reliance on imported water due to drought and climate change vulnerabilities.

To break this cycle, TVMWD and the Participating Agencies have prioritized regional mitigation projects focused on water quality treatment. For example, the proposed GRIP+ project - a major regional partnership between TVMWD, the City of Glendora, and the City of Pomona – and City of Pomona Groundwater Quality Improvement project (described in Section 3.9) involve installing wellhead treatment (such as GAC for TCP and anion exchange for nitrates) to rehabilitate stranded wells. By investing in groundwater treatment, the Region can restore local extraction capacity, fully utilize its groundwater basin storage, and secure a drought-resilient water portfolio.

Stranded Groundwater Assets and Evolving Regulations
As detailed above, the Region overlies several historic contaminant plumes (VOCs, perchlorate, nitrates).

While many of these legacy plumes are actively managed, the Region faces a significant, ongoing reliability threat from "moving regulatory targets" – specifically, the introduction of stricter MCLs for CECs.

For example, the EPA issued final National Primary Drinking Water Regulations for several PFAS compounds in April 2024 (EPA, 2024), and the SWRCB DDW continues to tighten state-level Public Health Goals and MCLs. When these new, ultra-low regulatory thresholds take effect, wells that previously met all safety standards instantly become non-compliant. These wells must be taken offline, creating "stranded assets."

3.3. Surface Water
While imported water and groundwater form the foundation of the Region’s water portfolio, local surface water provides a valuable, highly cost-effective supplemental supply. Between 2021 and 2025, local surface water use by TVMWD member agencies averaged 2,267 AFY, accounting for approximately 2 percent of the Region’s total water supply portfolio.

Surface water within the Region is primarily utilized in two ways: direct diversion for potable treatment and distribution, and diversion into spreading grounds for groundwater basin replenishment. Because surface water flows are entirely dependent on local precipitation and snowpack in the San Gabriel Mountains, this supply is highly variable and susceptible to drought conditions. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 53

3.3.1. Surface Hydrology and Major Sources
The surface hydrology of the Region is dominated by the San Gabriel Mountains to the north, which capture precipitation and generate runoff that flows southward into the valley floors. The Region spans portions of two major watersheds: the San Gabriel River watershed to the west and the Santa Ana River watershed (via San Antonio Creek) to the east.

San Gabriel River
The San Gabriel River is the primary surface water system serving the western portion of the TVMWD service area. The river's headwaters originate in the Angeles National Forest. Runoff is captured and regulated by a series of upstream dams (including Cogswell, San Gabriel, and Morris Dams) before flowing downstream into the Main San Gabriel Basin. Flows in the San Gabriel River are highly variable, with the majority of natural runoff occurring during the winter storm season (December through March).

San Antonio Creek
San Antonio Creek serves the eastern portion of the Region. Originating near Mount San Antonio (Mt.

Baldy), the creek flows southward through San Antonio Canyon. Flows are regulated by the San Antonio Dam, a flood control facility operated by the U.S. Army Corps of Engineers. Below the dam, the creek flows into the Six Basins and Chino Basin areas, where it is utilized for both direct supply and groundwater recharge.

3.3.2. Surface Water Diversions and Management
Unlike its role with imported water, TVMWD does not own surface water rights or operate self-supplied surface water diversion facilities to meet regional water demands. Instead, surface water rights are held and managed by specific retail member agencies and mutual water companies within the Region.

Key surface water management activities in the Region include:
⚫ Covina Valley Water Company: Formed through the merger of the Covina Irrigating Company and Valencia Heights Water Company, CVWC is a TVMWD member agency that holds pre-1914 appropriative rights to divert surface water from the San Gabriel River. These surface water rights are legally administered and apportioned through CVWC's membership in the San Gabriel River Water Committee (historically known as the "Committee of Nine" established by the 1889 Compromise Agreement) (documentation of the pre-1914 rights are included in Part 3, Appendix O). CVWC treats this local surface water (along with untreated imported water from TVMWD) at its William B. Temple Treatment Plant before supplying it to member agencies within the TVMWD region. Based on historical data from 2015 to 2022, CVWC diverts an average of 1,135 AFY of local surface water from the San Gabriel River. ⚫ City of Pomona: The City of Pomona holds pre-1914 appropriative rights (included in Part 3, Appendix P) to local surface water from San Antonio Creek and its local tributary watersheds (such as Evey Canyon). These surface water rights are shared with the San Antonio Water 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 54

Company via a diversion structure located upstream of the San Antonio Dam. Crucially, the 1998 Six Basins Adjudication Judgment explicitly reaffirmed the City of Pomona's right to continue harvesting this surface water for direct municipal use, independent of the basin's groundwater recharge obligations. The City diverts this water and treats it at the Pedley Filtration Plant, located in the City of Claremont, for potable use. Based on historical data from 2021 to 2025, Pomona diverts an average of 1,481 AFY of local surface water from the San Gabriel River. ⚫ TVMWD Recharge Operations: While TVMWD does not directly serve surface water to customers, it actively participates in the management of these flows to maximize regional groundwater storage. For example, TVMWD purchases San Antonio Creek surface water supplies from the City of Pomona to replenish the Six Basins. TVMWD also utilizes interconnections, such as Pomona’s Canon pipeline, to direct surface water to the San Antonio Spreading Grounds, directly benefiting TVMWD’s groundwater extraction wells located in the Six Basins.

3.3.3. Surface Water Quality and Climate Impacts
Because the TVMWD service area straddles a major hydrological divide, surface water quality is governed by two separate regulatory frameworks:
⚫ San Gabriel River Watershed: Governed by the SWRCB Plan for the Los Angeles Region (Region 4 Basin Plan) (LARWQCB, 2014).
⚫ San Antonio Creek Watershed: Governed by the SWRCB Plan for the Santa Ana River Basin (Region 8 Basin Plan) (SARWQCB, 2025).

These Basin Plans establish the beneficial use designations and water quality objectives for the Region's surface waters. Because the Participating Agencies divert surface water from the high-elevation, upper portions of these watersheds (upstream of major urban development), the ambient water quality is generally excellent and free of the urban runoff contaminants, industrial discharges, and 303(d) impairments that typically affect the lower reaches of these river systems. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 55

Source-Specific Quality and Treatment
While free of most industrial contaminants, local surface water is directly exposed to the natural environment and requires conventional treatment (coagulation, flocculation, sedimentation, filtration, and disinfection) to meet state and federal drinking water standards. ⚫ San Gabriel River: Water diverted by the CVWC from the San Gabriel River is characterized by low TDS and high historical purity. CVWC treats this water at its William B. Temple Treatment Plant.
⚫ San Antonio Creek: Water diverted by the City of Pomona from San Antonio Creek originates as mountain snowmelt and runoff from Mount San Antonio. It is treated at the City's Pedley Filtration Plant in Claremont.

The primary water quality challenge for both of these sources is turbidity (suspended sediment and organic matter) driven by weather events. During dry periods, the water is clear and easily treated.

However, during intense winter storms, rapid runoff causes severe spikes in turbidity. When turbidity levels exceed the operational thresholds of the filtration plants, agencies are forced to temporarily halt diversions and bypass the storm flows until the water clears, resulting in a loss of potential supply.

Table 3-14 describes the primary surface water quality challenges and concerns in the Region.

Table 3-14. Primary Surface Water Quality Challenges and Operational Impacts Water Quality
Challenge
Primary Source /
Cause
Impact on Supply
Reliability
Typical Mitigation / Treatment
Strategy
Turbidity (Suspended
Solids)
Heavy winter
rainstorms, rapid
snowmelt
High Nephelometric
Turbidity Unit (NTU) levels
can blind filters; forces
temporary shutdown of
diversion facilities.

Conventional filtration;
temporary bypass of high-flow
storm events.

Total Organic Carbon
(TOC)
Natural decay, post-
wildfire ash
Acts as a precursor for
DBPs when chlorinated.

Enhanced coagulation; careful
management of chlorine
dosing; blending with imported
water.

Ash and Debris Loads Post-wildfire runoff
from the San Gabriel
Mountains
Can physically damage
intakes and severely
degrade raw water quality
for extended periods.

Watershed management;
installation of protective intake
screens; temporary reliance on
groundwater/imported water.

Pathogens (Giardia,
Cryptosporidium)
Wildlife and natural
environmental
exposure
Requires strict compliance
with the Surface Water
Treatment Rule.

Multi-barrier treatment
(Filtration + UV or Chlorine
disinfection).

Climate Change and Wildfire Impacts
Because local surface water supplies are directly tied to precipitation, they are highly vulnerable to the impacts of climate change. As discussed in Section 2.5.2, TVMWD’s 2024 Climate Assessment modeled a "Dry Hot" (Drier with Extreme Warming) scenario against historical baselines (TVMWD, 2024a). As part of that Climate Assessment, projected changes in streamflow were modeled for the San Gabriel River 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 56

(specifically below Santa Fe Dam near Baldwin, USGS Gage 11085000) through the year 2045 (USGS, 2026).

The modeling revealed several critical vulnerabilities for the Region's surface water supplies:
⚫ Reduction in Total Flow: Under the Dry Hot scenario, annual streamflow in the San Gabriel River is projected to decrease by 10 percent by 2045 relative to the current climate. ⚫ Shift in Seasonal Timing: The hydrograph of the river is expected to shift significantly. Lower flows are projected during the historically high-flow months of February and March (decreasing by 20 to 21 cubic feet per second [cfs]), while precipitation shifts slightly earlier into the fall. ⚫ Increased Intensity and Shorter Seasons: The Region is projected to experience a shorter overall rainy season, but with the potential for higher-intensity storm events. This results in higher peak flows of shorter duration.

These hydrologic shifts dictate that river supplies will become less reliable for direct diversion. While natural groundwater recharge will still occur, the shifting timing and increased intensity of storm flows mean that existing diversion facilities and spreading grounds may face capacity constraints during flash- flood events. Consequently, the Region must adapt its surface water management strategies to ensure diversion facilities can capture and recharge these higher-intensity, higher turbidity, and shorter- duration flows before they are lost downstream.

3.4. Stormwater
Within the TVMWD service area, other than the surface water described in the prior section, stormwater is not directly diverted for potable use; rather, stormwater capture is a component of the Region’s conjunctive use and groundwater management strategy. The capture and percolation of local stormwater runoff is the primary mechanism for the natural replenishment of the Main San Gabriel, Six Basins, Chino, and Spadra groundwater basins. The volume of stormwater captured directly influences the OSY of these adjudicated basins, which in turn supports the local groundwater extraction totals detailed in Section 3.2.

3.4.1. Regional Stormwater Capture Facilities
Because TVMWD is a wholesale agency, it does not own or operate stormwater capture or flood control infrastructure. Stormwater capture is managed through highly coordinated partnerships with regional flood control districts and local protective associations. These entities operate networks of dams, diversion structures, and spreading grounds designed to capture stormwater runoff and percolate it into the underlying aquifers.

Key stormwater capture facilities benefiting the Region include:
⚫ Santa Fe Spreading Grounds (Main San Gabriel Basin): Operated by the Los Angeles County Department of Public Works (LACDPW), this facility captures runoff from the San Gabriel River watershed. Located in the upper portion of the Santa Fe Dam reservoir, the spreading grounds 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 57

utilize a rubber dam to direct river flows into percolation basins, capable of percolating approximately 400 cfs continuously.
⚫ Peck Road Water Conservation Park (Main San Gabriel Basin): Operated by the LACDPW, this facility captures stormwater runoff from the San Gabriel River and Arcadia Wash watersheds.

Functioning as both a recreational park and a critical water conservation asset, the facility utilizes a large primary lake and interconnected percolation basins to detain high-velocity storm flows. Impounding this water prevents it from bypassing the local groundwater system, instead allowing it to slowly infiltrate through highly permeable soils into the underlying Main San Gabriel Basin, actively supporting the Region's groundwater replenishment objectives. ⚫ San Antonio and Thompson Creek Spreading Grounds (Six Basins / Chino Basin): Owned and managed by the Pomona Valley Protective Association (PVPA) in coordination with the U.S.

Army Corps of Engineers and local Watermasters. Spanning approximately 1,000 acres, these facilities capture stormwater rushing out of San Antonio Canyon. Water impounded behind the San Antonio Dam is discharged in a controlled manner into PVPA diversion works, which utilize slide gates to divert high-velocity stormwater into gravel pits and channels for groundwater recharge.

Table 3-15 summarizes the primary stormwater capture and spreading facilities that support the Region’s groundwater basins.

Table 3-15. Major Stormwater Capture and Spreading Facilities Benefiting the Region Facility Name Managing/Operating Entity Primary Source Water Primary Basin(s) Recharged
Santa Fe Spreading
Grounds
Los Angeles County Dept. of
Public Works (LACDPW)
San Gabriel River Main San Gabriel
Basin
San Antonio Spreading
Grounds
Pomona Valley Protective
Association (PVPA) / USACE
San Antonio Creek Six Basins, Chino Basin
Thompson Creek
Spreading Grounds
PVPA / LACDPW Thompson Creek Six Basins
Peck Road Water
Conservation Park
Los Angeles County Dept. of
Public Works
San Gabriel River /
Arcadia Wash
Main San Gabriel
Basin

3.4.2. Climate Change Vulnerabilities and Planned Improvements As described in the Region's Climate Change Vulnerability Assessment (Section 2.5), local hydrology is projected to shift (TVMWD, 2024a). While the total volume of annual precipitation may not decrease drastically by 2050, projections show that the timing and intensity of that precipitation will.

The Region is projected to experience a shorter rainy season characterized by more severe, high- intensity "atmospheric river" events. This volatility poses a direct threat to stormwater capture: existing diversion facilities and spreading grounds may face capacity constraints during flash-flood events, resulting in vital water supplies bypassing the spreading grounds and being lost to the ocean. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 58

To mitigate this climate vulnerability, the Region is actively investing in infrastructure enhancements to increase the instantaneous capture capacity of local spreading grounds. These enhancements are described in more detail in Section 3.9.

3.5. Recycled Water and Wastewater
The development and utilization of recycled water is a critical strategy for the Region. Although implementing recycled water infrastructure requires significant capital investment, the supply is highly reliable because wastewater flows to treatment plants remain relatively constant regardless of hydrologic conditions. For this reason, recycled water is often considered a "drought-proof" supply.

Based on historical water use from 2021 to 2025, recycled water accounts for approximately 4 percent of the Region’s total water supply portfolio, providing an average of 6,224 AFY. Currently, TVMWD does not directly use or have access to recycled water at the wholesale level. Instead, several member agencies within the TVMWD service area utilize recycled water to meet non-potable demands, primarily for landscape irrigation and industrial uses.

3.5.1. Wastewater Collection and Treatment
To understand the potential for recycled water, it is necessary to quantify the wastewater generated and treated within the Region. Neither TVMWD nor the majority of its Participating Agencies provide wastewater collection or treatment services. Instead, wastewater collection and treatment within the Region is primarily managed by LACSD, along with local municipal sewer departments that maintain the collection pipelines conveying wastewater to LACSD's trunk sewers.

Recycled water sources in the Region are primarily derived from two LACSD-owned and operated water reclamation plants (WRPs):
⚫ Pomona WRP: Located within the City of Pomona, this facility treats wastewater generated by residential and commercial users in the eastern portion of the Region. The Pomona WRP provides primary, secondary, and tertiary treatment for a design capacity of 15 MGD. ⚫ San Jose Creek WRP: Located adjacent to the City of Industry, this larger facility serves a broader area of the San Gabriel Valley. The San Jose Creek WRP consists of two hydraulically interconnected facilities (East and West) that provide primary, secondary, and tertiary treatment for a combined design capacity of 100 MGD.

Table 3-16 summarizes the existing wastewater collection and treatment facilities serving the Region. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 59

Table 3-16. Wastewater Treatment Plants Serving the Region Facility
Name
Operating
Agency
Treatment
Level
Design
Capacity
(MGD)
2025 Average
Daily Flow
(MGD)
Effluent Use
Pomona
WRP
LACSD Tertiary 15 6.85 Non-potable reuse for irrigation; remaining discharged to San Jose
Creek1.

San Jose
Creek WRP
LACSD Tertiary 100 60.12 Non-potable reuse; groundwater recharge; remaining discharged to
San Gabriel River3.

1. Under SWRCB Wastewater Change Petition WW0104 (SWRCB, 2020a) (included in Part 3, Appendix Q), LACSD is legally permitted to reduce its discharge to San Jose Creek to zero to maximize recycled water reuse, meaning there are no minimum bypass flow obligations for downstream habitat.

2. Source: Sewerage Service "Will Serve" Documentation. As published in recent regional CEQA filings (e.g., City of Irwindale Final IS/MND, January 2025) (City of Irwindale, 2025).

3. Under SWRCB Wastewater Change Petition WW0107 (SWRCB, 2020b) (included in Part 3, Appendix R), LACSD is authorized to significantly reduce discharges to expand regional reuse. However, this authorization is subject to specific, enforceable minimum flow conditions negotiated with the SWRCB and California Department of Fish and Wildlife (e.g., maintaining ~5 MGD at specific outfalls) to protect downstream habitat and public trust resources.

3.5.2. Current Recycled Water Uses
While TVMWD does not distribute recycled water, six member agencies within the Region – the City of Pomona, Rowland WD, WVWD, Cal Poly Pomona, Mt. SAC, and the City of Industry – currently utilize tertiary-treated recycled water purchased from LACSD to offset potable water demands. This water is distributed through dedicated "purple pipe" systems and is primarily used for irrigation of parks, golf courses, schools, and roadway medians. Recycled water from LACSD is acquired by the Participating Agencies through individual service agreements rather than formal adjudicated entitlements. The total available recycled water supply is governed by the treatment capacity of LACSD's two regional WRPs – the Pomona WRP (15 MGD capacity) and the San Jose Creek WRP (100 MGD capacity) – as documented in Section 3.5.1.

The City of Pomona, Rowland WD, and WVWD are the largest utilizers of recycled water among the Participating Agencies. Furthermore, institutional partners such as Cal Poly Pomona utilize significant volumes of recycled water for campus landscaping and agricultural operations.

Table 3-17 summarizes the aggregated historical recycled water use by TVMWD agencies over the 2021–2025 baseline period.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 60

Table 3-17. Historical Annual Recycled Water Use by TVMWD Agencies (2021-2025) Water Source / Agency 2021 2022 2023 2024 2025 5-Year Average Participating Agencies 4,566 4,972 3,939 3,593 3,430 4,100 Other TVMWD Agencies* 2,126 2,126 2,126 2,126 2,126 2,126 Regional Total 6,682 7,098 6,065 5,719 5,555 6,226
*Note: To accurately reflect the total regional recycled water use, this table incorporates estimated recycled water use for Other Member Agencies within the TVMWD service area. Because these agencies are not formal signatories to this 2025 RUWMP, their historical recycled water use were estimated utilizing the best available public data, including related environmental documentation (e.g., EIRs) and 2020 UWMPs.

3.5.3. Planned Recycled Water Projects
The Region is actively exploring opportunities to expand the beneficial use of recycled water to further reduce dependence on imported water supplies. While expanding traditional "purple pipe" non-potable systems is ongoing, the Region is also investigating advanced purification and groundwater injection strategies. More detail is provided in Section 3.9.

3.6. Transfers and Exchanges
To maximize the reliability and efficiency of the Region's water supply, TVMWD and its Participating Agencies actively utilize transfers and exchanges. These water management strategies allow the Region to optimize existing resources, overcome localized water quality or infrastructure constraints, and ensure that water can be moved to where it is needed most, particularly during extended drought periods or emergency outages. While TVMWD serves as the primary conduit for importing water into the Region, the retail agencies themselves possess a highly interconnected distribution network. By leveraging joint powers authorities, shared pipelines, and cooperative agreements, the agencies can physically and contractually exchange water supplies.

Water transfers and exchanges involve the temporary or long-term trading of water rights or physical water supplies between agencies. In the TVMWD service area, these exchanges are facilitated by both physical interconnections and contractual agreements.

Existing Exchange Mechanisms and Infrastructure
A critical component of the Region's transfer capability is the Pomona-Walnut-Rowland JWL. The JWL is a shared transmission pipeline – not a standalone water right or active supply transfer program – that allows for the efficient movement of treated imported water (described in Section 3.1) among the City of Pomona, Rowland WD, and WVWD. While it does not currently generate 'new' supply, the JWL's physical interconnection makes future regional exchanges possible. For example, the planned Chino Basin Conjunctive Use Exchange (described in Section 3.9) relies entirely on the JWL to physically wheel Pomona's extracted groundwater westward to offset other agencies' imported water demands.

Additionally, the PBWA acts as a legal and administrative vehicle for executing water transfers, securing groundwater export rights, and developing shared infrastructure that benefits both districts. While the PBWA does not generate ‘new’ supply, it utilizes its authority to optimize regional reliability by banking 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 61

surplus water in the Main San Gabriel Basin (described in Section 3.2.1) and facilitate external surface water transfers, such as the planned partnership with the Covina Valley Water Company (described in Section 3.9).

In addition to these specific regional projects, TVMWD and the Participating Agencies continue to maintain emergency interties with neighboring systems to facilitate short-term transfers during facility outages or localized supply disruptions.

3.7. Supply From Storage
A foundational pillar of the Region’s water supply reliability is the proactive management of local groundwater basins through "conjunctive use." Conjunctive use is the strategic practice of storing imported surface water in local groundwater aquifers during wet years when supplies are abundant, and subsequently extracting that stored water during dry years when imported supplies are constrained.

This regional "water banking" strategy acts as a critical buffer, allowing the Participating Agencies to maintain sufficient supply to meet demands during single-dry and multi-year drought conditions without triggering severe mandatory rationing.

It is important to note that 'Supply from Storage' is not quantified as an independent, separate line item in the regional supply projections presented in Section 5. Because the Region actively practices conjunctive use, the withdrawal of banked water is physically realized through increased local well production during droughts. Therefore, the yields from the storage accounts detailed in this section are implicitly embedded within the regional 'Local Groundwater' supply totals. Listing storage as a separate supply source would result in an inaccurate double-counting of the Region's available water assets.

3.7.1. TVMWD Regional Storage Capacity and MWD Cyclic Storage TVMWD actively manages changes in annual water supply availability by utilizing storage accounts across multiple adjudicated basins. Across the Main San Gabriel, Six Basins, and Chino Basins, TVMWD has a combined authorized storage capacity of 54,890 AF.

A primary mechanism for utilizing this capacity is the Cyclic Storage Program established with MWD.

Under this program, MWD delivers imported water supplies to TVMWD for storage in advance of demand. This allows the Region to capture surplus imported supplies that would otherwise be lost to the ocean during high-precipitation years. TVMWD's Cyclic Storage Agreement with MWD (included in Part 3, Appendix K) allows for the pre-delivery and storage of up to 50,000 AF. Originally signed in 1991, this agreement was recently amended and extended through June 2034, ensuring long-term contractual reliability for the Region's banking operations.

MWD Chino Basin Conjunctive Use Program (Dry-Year Yield Program) In addition to cyclic storage accounts, TVMWD is a signatory partner in MWD’s Chino Basin Conjunctive Use Program (regionally referred to as the Dry-Year Yield Program, or DYYP). Executed in June 2003 in partnership with MWD, the Inland Empire Utilities Agency (IEUA), and the Chino Basin Watermaster, this 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 62

program is one of the largest active groundwater banking operations in Southern California (MWD et al., 2003) (Agreement provided in Part 3, Appendix T).

The DYYP provides a maximum authorized storage capacity of 100,000 AF within the Chino Basin, with a designed dry-year extraction yield of up to 33,000 AF per year. Under this arrangement, MWD stores surplus imported water in the Chino Basin during hydrologically wet periods using Proposition 13 state grant funds and MWD capital.

During severe droughts or periods of imported supply constraint, MWD can "call" on this stored water.

To execute the call, local participating pumpers extract the banked groundwater in lieu of taking treated imported water deliveries from MWD. This in-lieu exchange effectively frees up MWD's regional surface water supplies, reduces TVMWD's imported water demand during critical shortage years, and provides a highly reliable local buffer against SWP allocation cuts. Operating under an initial 25-year term (through 2028, with provisions for renewal or extension), the DYYP serves as a foundational component of the Region’s drought resilience strategy and illustrates the collaborative, conjunctive management required to navigate prolonged dry periods.

By the end of 2025, TVMWD is projected to hold approximately 14,000 AF of water in storage across its accounts. Table 3-18 summarizes the Region's aggregated groundwater storage portfolio, delineating between wholesale accounts managed by TVMWD and retail accounts managed by Joint Power Authorities (such as PBWA).
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 63

Table 3-18. TVMWD Regional Groundwater Storage Portfolio Summary Groundwater Basin Agreement Type Maximum Storage
Capacity (AF)
Estimated Stored Balance
(End of 2025) (AF)
Wholesale Storage
Main San Gabriel Basin Cyclic Storage
Agreement
50,000 3,079
Six Basins Operational Storage
Account
3,500 ~3,5001
Chino Basin One-Time Storage
Agreement
1,390 1,390
Spadra Basin Planned Optimization
Project
0 (Planned: 3,500) 0
Wholesale Subtotal 54,890 (Current)
58,390 (Current and
Planned)
~7,969
Retail / JPA Storage
Main San Gabriel Basin Storage and Export
Agreement
30,000 3,0002
Retail / JPA Subtotal 30,000 3,000
Regional Total 84,890 (Current)
88,390 (Current and
Planned)
~13,969
MWD Regional Storage
(Partnered)

Chino Basin MWD Conjunctive
Use Program (DYYP)
100,000 (shared with
IEUA)4
Managed by MWD3

1. Based on 2024 Annual Watermaster Report (Six Basins Watermaster, 2025). Final 2025 stored balances are subject to ongoing Six Basins Watermaster reconciliation.

2. Balance estimated based on the PBWA Board of Commissioners' October 2024 authorization to purchase 3,000 AF of cyclic storage for the 2025-2029 water years (PBWA, 2024b).

3. The 100,000 AF maximum capacity represents a regional MWD account shared with the IEUA. Because the stored water is owned by MWD and called at MWD's discretion, the current stored balance is excluded from TVMWD’s exclusive local storage totals to accurately reflect local asset control and avoid double-counting MWD supplies.

Groundwater banking programs are a formalized extension of the Region's conjunctive use strategy.

While general groundwater storage involves recharging the aquifer to maintain basin health, "banking" involves formal, contractual agreements that allow an agency to deposit a quantified volume of water into a basin and retain the legal right to extract, transfer, or export that specific volume of water at a later date.

Because the Region overlies multiple adjudicated and managed basins, groundwater banking requires close coordination with basin Watermasters to ensure that deposits and withdrawals do not negatively impact basin safe yields or water quality.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 64

3.7.2. Recharge Mechanisms and Operational Constraints
To physically place water into these groundwater storage accounts, TVMWD purchases untreated imported water from MWD and delivers it to various regional spreading grounds, such as the San Antonio Spreading Grounds (Six Basins) and the Santa Fe Spreading Grounds (Main San Gabriel Basin).

Water is also banked "in-lieu" by providing treated surface water to retail agencies, allowing them to turn off their groundwater pumps and leave their groundwater rights in the aquifer.

While TVMWD possesses significant "paper" storage capacity, the physical availability of spreading facilities and conveyance pipelines can limit the ability to fully utilize these programs. During extreme wet years, spreading grounds must be shared with local flood control and stormwater capture operations, occasionally limiting the volume of imported water that can be recharged simultaneously.

Planned Groundwater Mitigation Projects
To overcome these operational constraints and maximize the Region's conjunctive use potential, TVMWD and its member agencies have identified a suite of regional mitigation projects focused on expanding treatment capacity, installing new extraction and injection wells, and building interties to move stored water across the Region more effectively. These projects are described in more detail in Section 3.9.

3.8. Desalination Opportunities
The CWC requires urban water suppliers to evaluate the opportunities for the development of desalinated water, including ocean water, brackish surface water, and brackish groundwater, as a long- term supply. Desalination involves treating water with high salinity levels – typically using advanced membrane processes such as reverse osmosis (RO) – to produce potable drinking water.

3.8.1. Opportunities for Brackish Water and/or Groundwater Desalination Brackish groundwater refers to groundwater with elevated levels of TDS and salts, often resulting from historical agricultural practices or localized geological conditions.

Currently, the primary groundwater quality constraints within the Region are related to VOCs, nitrates, and CECs such as PFAS. Participating Agencies are actively investing in advanced water treatment infrastructure – including ion exchange and RO trains, such as the additions planned at the Cal Poly Pomona Water Treatment Plant – to address these specific contaminants.

While RO technology is capable of desalting brackish water, large-scale brackish groundwater desalination specifically for the purpose of salt removal is not currently a primary supply development strategy for the TVMWD service area. However, as regional salt and nutrient management plans continue to monitor TDS accumulation in shared basins like the Chino Basin, the deployment of desalter operations may become a more prominent opportunity in the future. At this time, the Region focuses its groundwater recovery investments on addressing industrial and chemical contaminants to restore stranded well assets rather than brackish desalting.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 65

3.8.2. Opportunities for Seawater Desalination
Because the TVMWD service area is located in inland eastern Los Angeles County, it is geographically landlocked. Therefore, the direct development of seawater desalination facilities within the Region is physically and economically infeasible.

However, the Region recognizes and supports seawater desalination as a vital component of Southern California's overall water supply reliability. MWD actively supports the development of seawater desalination by its coastal member agencies through the Local Resources Program (LRP). When coastal agencies develop local desalinated supplies, it offsets their demand for imported water from the SWP and the Colorado River. This reduction in coastal demand directly benefits inland agencies like TVMWD by increasing the availability and reliability of imported water in MWD's regional storage network.

Consequently, while TVMWD will not construct seawater desalination facilities, it indirectly relies on regional desalination advancements to bolster its imported water reliability.

3.9. Planned Water Supply Projects and Programs
As detailed throughout this chapter, the TVMWD service area relies on a complex, interconnected portfolio of imported and local water supplies. However, escalating climate change impacts – such as hydrologic volatility, prolonged droughts, and reduced imported water reliability – combined with increasingly stringent water quality regulations (e.g., new MCLs for PFAS), threaten the historical yield and flexibility of these resources.

To proactively mitigate these vulnerabilities and ensure long-term regional water security, TVMWD and its Participating Agencies have identified a suite of collaborative water supply projects and programs that focus on optimizing existing infrastructure, remediating stranded groundwater assets, expanding conjunctive use storage, and maximizing the physical capture and treatment of available local supplies.

The key planned regional projects, which are at various stages of evaluation, design, and implementation, are detailed in TVMWD’s 2025 WRMP (Part 3, Appendix H). These projects include:

Project 1: External Partnership with CVWC (formerly CIC) (Main Basin) Through the Puente Basin Water Agency (described in Section 3.2.1), the Region is pursuing an external partnership with CVWC to access existing surplus water supplies. This project involves the construction of a new pipeline intertie that will allow the pumping of surplus CVWC well and surface water from the Main San Gabriel Basin directly into the Badillo-Grand pipeline. By physically importing this surplus local water eastward, the intertie is estimated to provide up to 2,000 AFY of supply, directly offsetting the participating agencies' reliance on TVMWD imported water deliveries.

Project 2: TVMWD Groundwater Reliability Improvement Program (GRIP) This regional project would include a TVMWD partnership with the City of Glendora and the Puente Basin Water Agency to implement a regional distribution network and local supplies by utilizing 9,000 AF/year of stranded city assets. The regional distribution network would be augmented by the construction of new treatment facilities and conveyance pipelines. Three Valleys, as the lead agency, will 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 66

develop the project that includes new replacement wells with wellhead treatment for City of Glendora’s Wells #3, 4, and 7, and the pipeline and pumpstations. This regional project could also be expanded to address water quality concerns for more member agencies. This project would increase regional water supply reliability, thereby improving operational flexibility by integrating additional water sources into the existing network. This regional project would provide an estimated 9 TAF toward Three Valleys’ goal of increasing overall water supply by 15 TAF.

Project 3: TVMWD Storing Water in Main San Gabriel Basin (GRIP+) This project represents a major regional partnership between TVMWD, the City of Glendora, and the City of Pomona to maximize the storage of surplus imported water during wet years at the Santa Fe Spreading Grounds. To ensure this stored water can be efficiently recovered and distributed during droughts, the project expands physical extraction and conveyance capacity. Infrastructure plans include the installation of five new extraction wells (two dedicated to Glendora and three to Pomona) equipped with necessary wellhead treatments. Additionally, the project will construct approximately five miles of potable water pipeline to connect these Main San Gabriel Basin supplies directly to Pomona’s distribution system and the Pomona-Walnut-Rowland JWL. Once fully implemented, this project is anticipated to produce approximately 9,200 AFY of highly reliable local groundwater supply.

Project 4: TVMWD-Pomona Chino Basin Conjunctive Use Exchange Building upon the Region's successful participation in the existing MWD Dry-Year Yield Program detailed in Section 3.7.1, TVMWD and the City of Pomona are actively evaluating a mutually beneficial "in-lieu" exchange program to leverage the Chino Basin. While the MWD DYYP provides a broad regional buffer for the State Water Project, this planned TVMWD partnership focuses on highly localized infrastructure optimizations. Under this arrangement, TVMWD would provide funding to construct or upgrade Pomona’s extraction and treatment infrastructure in the Chino Basin. In exchange, Pomona would pump and deliver an equivalent amount of its local water for use by other TVMWD member agencies. This exchanged water would be conveyed westward via the JWL and the Badillo/Grand Transmission Main.

This creates a highly reliable local groundwater source for agencies that currently possess high dependencies on imported water (such as the City of La Verne, Golden State Water Company, and the Puente Basin Water Agency).

Other planned regional efforts and projects include:

Spadra Basin Optimization & Cal Poly Pomona Injection
This initiative combines multiple concepts to revitalize the non-adjudicated Spadra Basin using advanced treated recycled water. Spearheaded collaboratively by Walnut Valley Water District, the City of Pomona, and California State Polytechnic University, Pomona (Cal Poly), the optimization project proposes the construction of an underground recharge gallery, seven injection wells, five production wells, and the expansion of the Cal Poly Reverse Osmosis (RO) plant. A key component involves utilizing TVMWD’s Corporate Center Drive properties (adjacent to the I-57 and I-71 freeways) for new injection and extraction wells. By partnering with the Los Angeles County Sanitation Districts to secure advanced treated recycled water for injection, this project aims to create a drought-proof local storage asset with a capacity of up to 3,500 AF.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 67

Stormwater Capture Enhancements
To address the climate-driven shift toward shorter, higher-intensity winter storm events, the Region is upgrading its local spreading grounds to prevent volatile flash-flood flows from bypassing capture facilities. At the San Antonio Spreading Grounds, plans include excavating and developing new, deeper recharge basins (up to 200 feet in depth) to drastically increase instantaneous stormwater capture and storage volume. Concurrently, at the Thompson Creek Spreading Grounds, the Region is working in cooperation with the Los Angeles County Department of Public Works (LACDPW) to upgrade aging conveyance ditches and diversion structures to maximize the flow rate of water safely directed into the spreading basins.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 68

4. Regional Water Use
Accurately projecting regional water use is a critical component of water supply planning. Within the TVMWD service area, historical water demands have been heavily influenced by population growth, climate variability, and diverse land uses ranging from dense urban centers to large institutional campuses. However, as the Region looks toward 2050, water use trends are undergoing a significant transformation. Despite anticipated modest population and economic growth, overall regional water demands are projected to decline. This downward shift is driven by a strong local commitment to water use efficiency and the implementation of stringent new state conservation mandates.

This chapter provides a comprehensive overview of water demands across the Region. It details the aggregated historical and projected water use for the Participating Agencies and the Other Member Agencies. Furthermore, this chapter outlines the Region's successful compliance with past SB X7-7 targets and describes the transition to the new "Making Conservation a California Way of Life" (CWOL) regulatory framework, including the development of specific Urban Water Use Objectives (UWUOs).

Finally, it highlights the robust portfolio of regional and local Demand Management Measures (DMMs) and public outreach programs that the agencies are actively deploying to achieve these long-term efficiency goals.

4.1. Total Water Demands by Agency
As shown in Table 4-1, despite some continued growth due to infill and redevelopment, the total projected demand in the Region is expected to decline over time through 2050. This is due to implementation of the State’s new “Making Conservation a California Way of Life Regulation” (CWOL Regulation), which is discussed further in Section 4.2.2. To comply with the CWOL Regulation, it is anticipated that all the Participating Agencies will need to reduce their water demands relative to 2017 to 2021 demands. The reductions vary by agency and range from 9% (City of Pomona and GSWC – Claremont) to 37% (City of Glendora). This estimated reduction is based on the actual customer base in 2017-2021 so it does not account for demand increases from future growth. It is generally assumed that new growth will comply with water use efficiency standards due to current building codes.

Table 4-1. Projected Total Annual Retail Water Demand (RUWMP Participating Agencies) (Acre-Feet) Agency 2030 2035 2040 2045 2050
City of Glendora 10,004 9,878 9,696 9,517 9,342
City of La Verne 6,352 6,340 6,301 6,263 6,228
City of Pomona 20,147 20,116 19,917 19,719 19,521
GSWC – Claremont 9,873 9,603 9,262 8,941 8,644
GSWC – San Dimas 9,713 10,000 9,970 9,937 9,903
Rowland Water District 10,267 10,004 9,777 9,584 9,421
Walnut Valley Water District 16,369 15,246 14,559 14,580 14,589 Projected Total Demand 82,725 81,187 79,482 78,541 77,648 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 69

4.2. Water Use Efficiency
The Region has invested in expanding and optimizing local water resources to reduce reliance on imported supplies and maintain cost stability for its customers. At the same time, the Region continues to advance water use efficiency and conservation programs that have meaningfully reduced per capita demand and strengthened long-term supply reliability. These conservation efforts are a core component of the Region’s resource management strategy and help maximize the value of available supplies.

4.2.1. SB X7-7 Compliance
Senate Bill 7 of Special Extended Session 7 (SBX7-7) was incorporated into the UWMP Act in 2009 and requires that all water suppliers increase water use efficiency with the overall goal to decrease per capita water consumption within the state by 20 percent by the year 2020. SBX7-7 required DWR to develop certain criteria, methods, and standard reporting forms through a public process that water suppliers could use to establish their baseline water use and determine their water conservation targets.

SBX7-7 and DWR's Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use (DWR, 2016) specify methodologies for determining the baseline water demand, 2015 interim urban water use target, and the 2020 urban water use target for Western, as described in detail in the Participating Agencies’ 2020 UWMPs. All of the Participating Agencies met their targets to reduce per capita water consumption by 20 percent by 2020. For final verification in the 2025 UWMP, Section 3 of each retail agency chapter in Part 2 also demonstrates that the suppliers met its 2020 target.

4.2.2. New Water Conservation Legislation
Going forward, Participating Agencies that are retail suppliers are continuing to align with new water use efficiency standards from the CWOL Regulation, which supersede SBX7-7 standards. In 2018, two policy bills were enacted by the California Legislature, Assembly Bill 1668 (AB1668, Friedman) and Senate Bill 606 (SB606, Hertzberg), collectively referred to as the “2018 Water Conservation Legislation.” Based on the 2018 Water Conservation Legislation, related legislation, and subsequent adoption of the CWOL Regulation (SWRCB, 2024), each urban retail water supplier must calculate and comply with its specific Urban Water Use Objective (UWUO), with efficiency standards becoming increasingly stringent through 2040. DWR and the SWRCB have developed a reporting framework for calculating the UWUO and compliance annually. The UWUO is composed of several standards to create one comprehensive objective, as shown in Figure 4-1.

Figure 4-1. Urban Water Use Objectives Regulation Overview

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 70

Indoor Residential
The indoor residential water use standard was set as part of Senate Bill (SB) 1157, which adopts recommendations made by DWR and the State Water Board to reduce indoor water use targets from 55 gallons per capita per day (gpcd) to 47 gpcd by 2025 and 42 gpcd by 2030.

Outdoor Residential
Outdoor residential use is expected to be based on the amount of irrigable area and an increasingly stringent landscape efficiency factor with compliance progress measured annually through 2035, when the efficiency factor is proposed to remain constant. The SWRCB assists agencies in calculating outdoor residential use budgets by providing aerial imagery that delineates irrigable irrigated, irrigable but not irrigated, and non-irrigable areas. This data has been provided to suppliers and is expected to be updated in five-year cycles.

Commercial, Industrial, and Institutional Landscape
Commercial, industrial, and institutional (CII) standards will be based on total gallons used and will require implementation of dedicated irrigation meters or in-lieu technologies, and other performance measures for conservation. Additionally, CII customer accounts will need to be classified into specific and general categories for reporting and compliance over the course of several years yet to be determined by the State.

Water Loss
The water loss component of the UWUO is a standalone component that must be met on its own beginning in 2028. Section 2.1.3 of each retail agency chapter in Part 2 describes the water loss standard and the agency’s progress toward meeting it.

Additionally, each urban retail water supplier must submit an Annual Water Use Report (AWUR) starting January 1, 2024 to document progress toward complying with the UWUO regulations.

As discussed in Section 2.2 of each retail agency chapter in Part 2, some Participating Agencies in this RUWMP elected to incorporate the conservation that would be required to meet the UWUO into the future demand projections directly and some elected to assume less conservation than would be required to meet the UWUO for the purpose of more conservative supply planning. The required calculations and reporting associated with the CWOL Regulations are complex and extensive and are therefore not required to be included in the UWMP.

4.2.3. Regional Demand Management Programs
TVMWD retail agencies have adopted water waste prevention ordinances, universal metering, tiered conservation pricing, and robust public education and outreach programs, as described in Section 8 of each retail agency chapter in Part 2. Common measures include active leak detection, annual water loss audits, and dedicated conservation staffing to support program implementation. All seven retail agencies participate in one or more components of MWD’s regional rebate program: SoCal Water$mart. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 71

This program includes rebates for high efficiency indoor fixtures, irrigation devices, and turf removal.

Other programs offered by retailers, or through participation with MWD, include water use efficiency surveys and leak repair programs.

Retail agencies have also launched unique and innovative efforts. La Verne provides video-based water‑wise landscaping training classes that teaches how to use rainwater as a resource and manage irrigation in backyards. Walnut Valley installed Hydrant Guard check valves, which aim to reduce catastrophic water loss associated with broken fire hydrants. Rowland Heights offers multi‑tiered school and youth education programs. Rowland Heights and Glendora have each deployed advanced metering systems with customer leak alerts and usage analytics. Pomona participates in, or hosts, more than a dozen events throughout the year including the “Water is Life” art poster and essay contest. Pomona also has a Water Watcher reporting line (online and via phone) for reporting visible leaks or excess runoff.

These regional and local programs work together to support the Region’s strategy to reduce demand, improve efficiency, reduce water loss, and reinforce conservation as California way of life. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 72

5. Comparison of Regional Supplies and Demands
The continuous and reliable provision of potable water is the foundational mandate of urban water suppliers. In accordance with California Water Code § 10635(a), every urban water supplier must assess the reliability of its water service by comparing total projected water use with the projected water supply over a planning horizon of at least 20 years.

This chapter provides that core statutory assessment for the TVMWD service area as a whole, extending the planning horizon out to 2050 to ensure robust long-term resiliency. The analysis rigorously stress- tests the Region's water portfolio under varying hydrological conditions, specifically encompassing a Normal Water Year, a Single Dry Year, a drought scenario lasting Five Consecutive Water Years, and a highly conservative Twenty-Year Drought scenario.

To navigate the complexities of shared imported water aqueducts and interconnected groundwater aquifers, this chapter synthesizes supply and demand data gathered from across the entire 133-square- mile TVMWD service area. As established in Section 1, the aggregated "Regional Context" analysis meticulously integrates projections for both the seven Participating Agencies and the Other Member Agencies. By systematically incorporating all entities that draw upon the Region's shared infrastructure, the ensuing analysis provides a highly accurate, bottom-up aggregation of the regional water balance.

The water service reliability assessment for each of the Participating agencies individually is presented in Chapter 5 of the respective chapters in Part 2.

5.1. Supply and Demand Projections Methodology
Evaluating water supply reliability through the year 2050 requires sophisticated forecasting methodologies that account for complex demographic shifts, the escalating impacts of climate change, evolving regulatory constraints, and behavioral modifications in urban water consumption. The analytical framework developed for this 2025 RUWMP utilizes ground-truthed projections and operationally conservative supply capability assessments to rigorously test the Region's overall water portfolio.

5.1.1. Demand Projections
The demand projections utilized in this comparison (detailed in Chapter 4) were generated using a multi-scenario analytical approach. Recognizing that a single, flat population growth multiplier is insufficient for modern water planning, distinct demand projection methodologies were developed for each agency. These dynamic scenarios ranged from baseline trend continuations to aggressive conservation scenarios modeled to ensure statutory compliance with the new CWOL Regulation.

Through collaborative working sessions, each participating agency selected the specific methodology most representative of its local service area dynamics, accounting for factors such as high-density infill development, the prevalence of Accessory Dwelling Units (ADUs), and historical per capita usage trends.

Crucially, the finalized demand projections incorporate both "Passive Conservation" (savings achieved 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 73

organically through the natural replacement of older plumbing fixtures per California building codes) and "Active Conservation" (savings derived from agency-sponsored rebate initiatives and turf-removal programs). Detailed explanations of the demand projection methodology used for each of the Participating Agencies are included in Section 2.2 of each agency chapter in Part 2.

5.1.2. Supply Projections
Water supply reliability planning frequently grapples with the discrepancy between contractual water rights (theoretical capacity) and actual, physical water availability (operational reality). To systematically address potential differences, the analytical framework for the 2025 RUWMP evaluated two distinct methodologies for projecting future local water supply: the "Paper Water" approach and the "Real Water" approach.
⚫ Option 1: The "Real Water" Approach (Utilization-Based): This approach is grounded strictly in empirical operational data. Under this framework, the baseline local agency supplies are tied directly to the actual historical averages extracted and utilized between the years 2021 and 2025. This period provides a good representation of hydrologic variations because it includes the severe, critically dry conditions of 2021–2022, the exceptionally wet hydrology of 2023, and the transitional conditions of 2024-2025. This period also reflects the most recent operational constraints that impact supply availability. By capturing recent shifts in groundwater availability – specifically, extraction wells taken offline or restricted due to newly implemented PFAS and CEC water quality regulations – this baseline ensures the supply projections reflect current physical reality rather than outdated infrastructure capacities. ⚫ Option 2: The "Paper Water" Approach (Capacity-Based): This approach projects future supply based on the maximum legal rights or absolute physical extraction capacity an agency holds within a basin. While useful for demonstrating legal entitlements and maximum potential supply, this approach can inadvertently mask critical infrastructure bottlenecks or localized water quality constraints (such as expanding contaminant plumes) that prevent an agency from accessing its full theoretical allocation.

To ensure the most conservative, defensible, and operationally realistic stress-test possible, the Participating Agencies unanimously selected the "Real Water" approach for their primary supply projections in this 2025 RUWMP. Once this empirical 2021–2025 baseline was established, specific climate change factors – derived from TVMWD's 2024 Climate Assessment (TVMWD, 2024a; provided in Part 3, Appendix I) and updated through 2025 for these analyses – were applied to project the degradation, volatility, or shift in local supply availability through 2050. Any projected unmet demand remaining after these adjusted local supplies are exhausted is assumed to be met by imported water supply deliveries from TVMWD and MWD.

Detailed explanations of the supply projection methodology used for each of the Participating Agencies are included in Section 4 of each agency chapter in Part 2. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 74

5.2. Summary of Regional Supplies and Demands
The core statutory requirement of the UWMP is the direct comparison of total water supply sources available to the water supplier with the long-term total projected water use over the next 20 years, in five-year increments. This assessment determines if the Region possesses the physical, contractual, and infrastructural capacity to support its population through 2050 under varying climatic stressors.

Because the Participating Agencies selected the "Real Water" (Utilization-Based) methodology for this analysis, projected supplies are managed conjunctively to meet projected demands. Any localized deficits in groundwater or surface water are met by imported water deliveries from TVMWD and MWD.

To understand the supply and demand comparisons in the following sections, it is critical to understand how the Region’s water portfolio changes under hydrological stress.

A key trend in Southern California urban water management is that during dry years, water demand typically increases. Hotter baseline temperatures and a lack of natural precipitation drive residents and institutional campuses to increase outdoor irrigation to maintain landscaping. To meet this increased demand, the retail agencies adapt their operations. Some agencies ramp up extraction from local groundwater wells (drawing upon cyclical storage accounts), and agencies heavily reliant on imported water lean more on TVMWD to supply imported water from MWD.

As discussed in Section 3.2.1, Metropolitan’s 2025 UWMP projects 100 percent imported water supply reliability under normal year, single dry year and 5 consecutive dry year scenarios and that conclusion is incorporated into this analysis (MWD, 2026b).

5.2.1. Normal Year
A "Normal Year" assessment evaluates the system under average climate conditions and standard baseline water yields. For this 2025 RUWMP, the Normal Year is defined by the average historical hydrology and usage patterns observed over the 2021–2025 baseline period. It is important to note that this specific five-year baseline applies exclusively to the Region's local supplies and retail demands; projected imported water availability relies on MWD's independent 2025 UWMP reliability modeling, which utilizes its own distinct, long-term historical baselines.

To accurately forecast reliability through 2050, the long-term climate change factors derived from the Region's 2024 Climate Assessment (described in Section 2.5.2) were applied to these baseline local supplies (described in Section 3) to account for projected warming, increased evapotranspiration, and shifting precipitation patterns. Additionally, the aggregated Normal Year demand projections incorporate anticipated demographic growth (described in Section 2.3) and the strict, mandatory active and passive conservation targets required by the new CWOL Regulations (described in Section 4).

Based on this thorough analysis, the TVMWD RUWMP Participating Agencies and entire service area exhibit total supply reliability through the year 2050. Table 5-1 and Table 5-2 detail the Normal Year 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 75

Supply and Demand comparison in five-year increments through 2050 for the specific Participating Agencies and the entire TVMWD service area, respectively. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 76

Table 5-1. Normal Year Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) Category 2030 2035 2040 2045 2050
Local Groundwater 31,495 32,173 31,697 31,046 30,225
City of Glendora 9,090 9,018 8,864 8,642 8,357
City of La Verne 1,849 1,834 1,803 1,758 1,700
City of Pomona 13,266 13,160 12,936 12,612 12,196
GSWC - Claremont 4,593 4,534 4,493 4,456 4,420
GSWC - San Dimas 1,996 1,970 1,952 1,937 1,921
Rowland Water District 700 1,657 1,649 1,641 1,633
Recycled Water1 5,058 5,132 5,191 5,234 5,263
City of Pomona 1,874 1,874 1,874 1,874 1,874
Rowland Water District 1,033 1,127 1,219 1,309 1,396
Walnut Valley Water District 2,152 2,131 2,098 2,051 1,993 Surface Water 1,691 1,674 1,649 1,616 1,576
City of Pomona 1,691 1,674 1,649 1,616 1,576
Imported Water (TVMWD/MWD) 41,991 37,199 35,956 35,684 35,658 City of Glendora 906 853 825 867 977
City of La Verne 4,503 4,506 4,498 4,505 4,528
City of Pomona 3,315 3,408 3,458 3,617 3,876
GSWC - Claremont 5,280 5,069 4,769 4,485 4,224
GSWC - San Dimas 7,036 7,321 7,310 7,294 7,278
Rowland Water District 7,433 6,128 5,836 5,588 5,380
Walnut Valley Water District 13,518 9,915 9,261 9,329 9,396 Imported Water (Other)2 2,491 5,009 4,988 4,960 4,926
City of Glendora 8 8 7 8 9
GSWC - San Dimas 682 709 707 706 705
Rowland Water District 1,101 1,092 1,073 1,047 1,012
Walnut Valley Water District 700 3,200 3,200 3,200 3,200 Projected Total Supply 82,726 81,187 79,481 78,541 77,648 City of Glendora 10,004 9,878 9,696 9,517 9,342
City of La Verne 6,352 6,340 6,301 6,263 6,228
City of Pomona 20,147 20,116 19,917 19,719 19,521
GSWC - Claremont 9,873 9,603 9,262 8,941 8,644
GSWC - San Dimas 9,714 10,000 9,969 9,937 9,904
Rowland Water District 10,267 10,004 9,777 9,584 9,421
Walnut Valley Water District 16,369 15,246 14,559 14,580 14,589 Projected Total Demand 82,726 81,187 79,481 78,541 77,648

1. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 77

2. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).

Table 5-2. Normal Year Supply and Demand (Regional Total – All Agencies) (Acre-Feet) Category 2030 2035 2040 2045 2050
Local Groundwater 65,872 66,550 66,074 65,448 64,627
Recycled Water1 7,688 7,762 7,821 7,864 7,893
Surface Water 2,541 2,524 2,499 2,466 2,426
Imported Water (TVMWD/MWD) 60,832 56,210 54,998 54,755 54,729 Imported Water (Other)2 16,239 18,756 18,735 18,708 18,673 Projected Total Supply 153,172 151,803 150,127 149,241 148,348 Projected Total Demand 153,172 151,803 150,127 149,241 148,348

1. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.

2. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).

5.2.2. Single Dry Year
A "Single Dry Year" assessment models the reliability of the system under acute, short-term hydrological stress. To accurately model this scenario and predict future behavior, the analysis utilizes empirical data from the 2021 fiscal year, which represents a severe, comprehensively documented dry-year condition within the Region.

Based on TVMWD's operational data, the historical average year baseline was established using the five- year period of 2021–2025. During dry years, hotter temperatures and a lack of rainfall typically drive increased outdoor irrigation, resulting in higher overall water demand. To project future drought demands, historical peaking factors were calculated and applied to the projected normal year demands:
⚫ RUWMP Participating Agencies: The ratio of water utilized by the seven Participating Agencies during 2021 (94,504 AF) to their historical average (83,031 AF) yielded a higher scaling factor of 114 percent.
⚫ Regional Total (All Agencies): The ratio of water utilized by all 13 agencies during the historical single dry year of 2021 (156,297 AF) to the historical average (144,907 AF) yielded a scaling factor of 108 percent.

These respective scaling factors (114% and 108%) were applied to the projected normal year demands to forecast the elevated water demands during future single dry years. As shown in Table 5-3 and Table 5-4, the Region possesses the physical and contractual capacity to completely fulfill these elevated demands, indicating total reliability during all future Single Dry Year events modeled through 2050. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 78

Table 5-3. Single Dry Year Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) Category 2030 2035 2040 2045 2050
Local Groundwater 35,847 36,619 36,077 35,336 34,402
Recycled Water1 5,757 5,841 5,908 5,957 5,990
Surface Water 1,925 1,906 1,877 1,839 1,793
Imported Water (TVMWD/MWD) 47,793 42,339 40,925 40,615 40,586 Imported Water (Other)2 2,835 5,701 5,677 5,646 5,606
Projected Total Supply 94,157 92,406 90,464 89,393 88,377 Projected Total Demand 94,157 92,406 90,464 89,393 88,377

1. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.

2. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).

Table 5-4. Single Dry Year Supply and Demand (Regional Total – All Agencies) (Acre-Feet) Category 2030 2035 2040 2045 2050
Local Groundwater 71,050 71,781 71,267 70,592 69,707
Recycled Water1 8,292 8,372 8,436 8,482 8,513
Surface Water 2,741 2,723 2,696 2,660 2,616
Imported Water (TVMWD/MWD) 65,614 60,629 59,321 59,059 59,031 Imported Water (Other)2 17,515 20,231 20,208 20,178 20,141 Projected Total Supply 165,212 163,736 161,928 160,972 160,009 Projected Total Demand 165,212 163,736 161,928 160,972 160,009

3. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.

4. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).

5.2.3. Five-Consecutive Dry Year and Drought Risk (2026-2030) Assessments In accordance with California Water Code Section 10635(b), the evaluation of a drought lasting five consecutive water years serves as the Region's statutory Drought Risk Assessment (DRA). This assessment verifies the near-term resiliency of the Region's cyclic storage mechanisms and wholesale contracts by stress-testing the limits of aquifer drawdown and reservoir depletion over the immediate five-year planning horizon (2026 through 2030).

To estimate demands during a five-consecutive-year drought, the Region utilized the historical drought sequence from 2018 through 2022. The ratio of water utilized in each of these years was compared to the 2021-2025 historical average to yield specific annual scaling factors. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 79

⚫ RUWMP Participating Agencies: The historical water demand sequence yielded scaling factors of 112 percent, 102 percent, 107 percent, 114 percent, and 107 percent for years one through five.
⚫ Regional Total (All Agencies): The historical water demand sequence yielded scaling factors of 112 percent, 102 percent, 107 percent, 108 percent, and 104 percent for years one through five of the drought, respectively.

These sequences of scaling factors were applied to the projected normal year demands to forecast the fluctuating, but consistently elevated, demands of a multi-year drought.

As shown in Table 5-5 and Table 5-6, because the Region’s groundwater basins are managed holistically using OSY, agencies are legally and physically permitted to intentionally draw down aquifer levels during a prolonged five-year drought starting in 2026, balancing the overdraft with replenishment during subsequent wet years. Consequently, backed by MWD's surface reservoirs and local groundwater banks, the Region projects sufficient supply capacity to meet these scaled demands across a five-year drought horizon through 2030.

Table 5-5. Regional Drought Risk Assessment (2026-2030) Supply and Demand by Source (RUWMP Participating Agencies) (Acre-Feet)
Category 2026 2027 2028 2029 2030
Local Groundwater 35,241 32,127 33,642 35,847 33,634
Recycled Water1 5,660 5,160 5,403 5,757 5,402
Surface Water 1,893 1,725 1,807 1,925 1,806
Imported Water (TVMWD/MWD) 46,986 42,834 44,853 47,793 44,843 Imported Water (Other)2 2,787 2,541 2,661 2,835 2,660
Projected Total Supply 92,567 84,387 88,365 94,157 88,346 Projected Total Demand 92,567 84,387 88,365 94,157 88,346

1. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.

2. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 80

Table 5-6. Regional Drought Risk Assessment (2026-2030) Supply and Demand by Source (Regional Total – All Agencies) (Acre-Feet)
Category 2026 2027 2028 2029 2030
Local Groundwater 73,708 67,194 70,361 71,050 68,201
Recycled Water1 8,602 7,842 8,212 8,292 7,960
Surface Water 2,844 2,592 2,715 2,741 2,631
Imported Water (TVMWD/MWD) 68,069 62,054 64,978 65,614 62,983 Imported Water (Other)2 18,170 16,565 17,345 17,515 16,813 Projected Total Supply 171,393 156,247 163,612 165,212 158,588 Projected Total Demand 171,393 156,247 163,612 165,212 158,588

1. To accurately reflect the separation of the Region's potable and non-potable distribution systems, it is assumed that projected Recycled Water supply strictly equals Recycled Water demand for non-potable uses. All other water supplies listed in this table are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands.

2. This category represents water supplies purchased, transferred, or imported from entities other than TVMWD/MWD (described in Section 3.1.4).

While Table 5-5 and Table 5-6 illustrate the detailed shift in supply sources for the 2030 horizon, Table 5-7 and
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 81

Table 5-8 demonstrate the Region's total supply reliability across all five-year drought horizons through 2050.

Table 5-7. Multiple Dry Years Supply and Demand (RUWMP Participating Agencies) (Acre-Feet) Sequence Year Category 2030 2035 2040 2045 2050
First Year Projected Supply 92,567 90,845 88,936 87,884 86,885 Projected Demand 92,567 90,845 88,936 87,884 86,885
Surplus / Deficit 0 0 0 0 0
Second Year Projected Supply 84,387 82,817 81,077 80,118 79,207 Projected Demand 84,387 82,817 81,077 80,118 79,207
Surplus / Deficit 0 0 0 0 0
Third Year Projected Supply 88,365 86,721 84,898 83,894 82,940 Projected Demand 88,365 86,721 84,898 83,894 82,940
Surplus / Deficit 0 0 0 0 0
Fourth Year Projected Supply 94,157 92,406 90,464 89,393 88,377 Projected Demand 94,157 92,406 90,464 89,393 88,377
Surplus / Deficit 0 0 0 0 0
Fifth Year Projected Supply 88,346 86,702 84,880 83,876 82,922 Projected Demand 88,346 86,702 84,880 83,876 82,922
Surplus / Deficit 0 0 0 0 0

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 82

Table 5-8. Multiple Dry Years Supply and Demand (Regional Total - All Agencies) (Acre-Feet) Sequence Year Category 2030 2035 2040 2045 2050
First Year Projected Supply 171,393 169,861 167,985 166,994 165,995 Projected Demand 171,393 169,861 167,985 166,994 165,995 Surplus / Deficit 0 0 0 0 0
Second Year Projected Supply 156,247 154,851 153,141 152,237 151,326 Projected Demand 156,247 154,851 153,141 152,237 151,326 Surplus / Deficit 0 0 0 0 0
Third Year Projected Supply 163,612 162,149 160,359 159,412 158,458 Projected Demand 163,612 162,149 160,359 159,412 158,458 Surplus / Deficit 0 0 0 0 0
Fourth Year Projected Supply 165,212 163,736 161,928 160,972 160,009 Projected Demand 165,212 163,736 161,928 160,972 160,009 Surplus / Deficit 0 0 0 0 0
Fifth Year Projected Supply 158,588 157,171 155,435 154,518 153,593 Projected Demand 158,588 157,171 155,435 154,518 153,593 Surplus / Deficit 0 0 0 0 0

2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 83

6. References
California Department of Finance (DOF). (2025, May). E-5 Population and Housing Estimates for Cities, Counties, and the State, 2020-2025. Demographic Research Unit, Sacramento, CA.

California Department of Water Resources (DWR). (2016, February). Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use. Sacramento, CA.

California Department of Water Resources (DWR). (2025, December). 2025 State Water Project Delivery Capability Report. Sacramento, CA.

California Department of Water Resources (DWR) (2026a, February). Urban Water Management Plan Guidebook, State of California Natural Resources Agency.

California Department of Water Resources (DWR). (2026b). California Irrigation Management Information System (CIMIS) Station 78 - Pomona. Accessed February 2026.

Chino Basin Watermaster. (2020, October). Optimum Basin Management Program (OBMP) Update.

The OBMP Update is available at this link.

City of Irwindale. (2025, January). Final Initial Study/Mitigated Negative Declaration for 14005 Live Oak Avenue Project. Available at: The Final IS/MND is available at this link.

Los Angeles Regional Water Quality Control Board (LARWQCB). (2014, September). Water Quality Control Plan, Los Angeles Region (Basin Plan for the Coastal Watersheds of Los Angeles and Ventura Counties). The Water Quality Control Plan is available at this link.

Main San Gabriel Basin Watermaster. (2023). Five-Year Water Quality and Supply Plan (2023-2028).

Azusa, CA.

Main San Gabriel Basin Watermaster. (2025, May). Final Determination of Operating Safe Yield for 2025- 26 Through 2029-30. Available at: The Final Determination is available at this link.

Metropolitan Water District of Southern California (MWD). (2025). Rate Structure Administrative Procedures Handbook (FY24/25). The 2024 to 2025 handbook is available at this link.

Metropolitan Water District of Southern California (MWD). (2026a, January). Rate Structure Administrative Procedures Handbook (FY25/26).

The 2025 to 2026 handbook is available at this link.

Metropolitan Water District of Southern California (MWD). (2026b, February). 2025 Urban Water Management Plan. The MWD 2025 UWMP is available at this link. 2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 84

Metropolitan Water District of Southern California (MWD), Inland Empire Utilities Agency (IEUA), Chino Basin Watermaster, and Three Valleys Municipal Water District (TVMWD). (2003, June). Chino Basin Dry-Year Yield Program Agreement.

The MWD, IEUA, TVWMD agreement is available at this link.

Puente Basin Water Agency (PBWA). (2023, December). Final TM-1: Conceptual Understanding of Puente Basin Technical Memorandum. The technical memorandum is available at this link.

Puente Basin Water Agency (PBWA). (2024a, March). Final TM-2: Goals and Concepts for Improved Basin Management Technical Memorandum. The technical memorandum is available at this link.

Puente Basin Water Agency (PBWA). (2024b, October). Minutes Of Meeting Of The Board Of Commissioners Of Puente Basin Water Agency.

The PBWA board meeting minutes are available at this link.

Puente Basin Water Agency (PBWA). (2025, June). Final TM-3: Basin Management Alternatives for the Puente Basin Groundwater Management Plan.

The final PBWA technical memorandum is available at his link.

San Bernardino County Superior Court. (2017, April 28). Order Regarding Safe Yield Reset (Case No.

RCVRS 51010).

San Gabriel Valley Economic Partnership and California State Polytechnic University, Pomona (SGVEP & Cal Poly Pomona). (2025). 2025 San Gabriel Valley Economic Forecast.

Santa Ana Regional Water Quality Control Board (SARWQCB). (2025, April). Water Quality Control Plan for the Santa Ana River Basin. The SARWQCB plan is available at his link.

Six Basins Watermaster. (2025, March). 2024 Annual Watermaster Report.

The Six Basins report is available at his link.

Southern California Association of Governments (SCAG). (2024). Connect SoCal 2024: The 2024-2050 Regional Transportation Plan/Sustainable Communities Strategy. Los Angeles, CA.

Spadra Basin Groundwater Sustainability Agency (GSA). (2022, January). Groundwater Sustainability Plan for the Spadra Basin. Prepared by West Yost Associates.

The Spadra Basin GSA is available at his link.

State Water Resources Control Board (SWRCB). (2020a, October). Order Approving Change in Place of Use, Purpose of Use, and Quantity of Discharge (Wastewater Change Petition WW0104).

The SWRCB 2020a Order is available at this link.

State Water Resources Control Board (SWRCB). (2020b, October). Order Approving Change in Place of Use, Purpose of Use, and Quantity of Discharge (Wastewater Change Petition WW0107). The SWRCB 2020b Order is available at this link.
2025 Regional Urban Water Management Plan
Three Valleys Municipal Water District
April 2026

GEI Consultants, Inc. 85

State Water Resources Control Board (SWRCB). (2024). Making Conservation a California Way of Life Regulation. Adopted July 3, 2024. Sacramento, CA.

The SWRCB 2024 regulation is available at this link.

Three Valleys Municipal Water District (TVMWD). (2024a, July). Climate Change Vulnerability Assessment. [Unpublished internal report]. Three Valleys Municipal Water District, Claremont, CA. Available upon request.

Three Valleys Municipal Water District (TVMWD). (2024b, November). Annual Comprehensive Financial Report for the Fiscal Years Ended June 30, 2024.

The TVMWD annual report is available at this link.

Three Valleys Municipal Water District (TVMWD). (2025, February). Water Resources Master Plan.

The TVMWD 2018-2023 master plan is available at this link.

U.S. Census Bureau. (2024). American Community Survey (ACS) 5-Year Estimates, 2018-2023. Accessed via the California Department of Water Resources Disadvantaged Communities (DAC) Mapping Tool.

U.S. Environmental Protection Agency (EPA). (2024, April). PFAS National Primary Drinking Water Regulation. Washington, D.C.

U.S. Geological Survey (USGS). (2026). National Water Information System data (USGS Water Data for the Nation), Gage 11085000. The USGS regulation is available at this link.

THREE VALLEYS REGIONAL URBAN

WATER MANAGEMENT PLAN
Local Agency
Urban Water Management Plans

PUBLIC REVIEW DRAFT
2025 Part 2:

APRIL 2026
2025 RUWMP
City of Pomona
2025 Urban Water Management Plan
Part 2 Chapter 4:

APRIL 2026
Prepared by GEI Consultants, Inc. and Water Systems Consulting, Inc.

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. i
Table of Contents
Acronyms and Abbreviations ................................................................................... iv Individual UWMP ..........................................................................................................vi

1. System Description ............................................................................................ 1

1.1. Service Area 3

1.1.1. Population, Demographics, and Socioeconomics 3

1.1.2. Land Use 4

2. Water Use .............................................................................................................. 5

2.1. Water Use by Sector 5

2.1.1. Water Use Sectors Listed in Water Code 5

2.1.2. Past and Current Water Use 6

2.1.3. Distribution System Water Losses 6

2.2. Projected Water Use 10

2.3. Climate Change Considerations 11

3. SB X7-7 Compliance & Future Water Use Efficiency
Requirements ................................................................................................... 12

3.1. Compliance and Future Water Use Efficiency Requirements 12

4. Water Supply ..................................................................................................... 13

4.1. Purchased or Imported Water 13

4.2. Groundwater 13

4.2.1. Chino Basin 13

4.2.2. Six Basins 14

4.2.3. Spadra Basin 14

4.3. Surface Water 15

4.4. Stormwater 15

4.5. Wastewater and Recycled Water 15

4.5.1. Potential, Current, and Projected Recycled Water Uses 16

4.6. Water Exchanges and Transfers 18

4.7. Future Water Projects 18

4.8. Summary of Existing and Planned Sources of Water 19

4.9. Energy Intensity of Water Supplies 21

5. Water Service Reliability Assessment ...................................................... 22

5.1. Constraints on Water Sources 22

5.2. Year Type Characterization 22

5.3. Water Service Reliability 24
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. ii

6. Drought Risk Assessment ............................................................................. 27

6.1. Data, Methods, and Basis for Water Shortage Conditions 27

6.2. DRA Water Source Reliability 27

6.3. Total Water Supply and Use Comparison 27

7. Water Shortage Contingency Plan ............................................................. 29

8. Demand Management Measures ................................................................ 30

8.1. Existing Demand Management Measures 30

8.1.1. Water Waste Prevention Ordinances 30

8.1.2. Metering 31

8.1.3. Conservation Pricing 31

8.1.4. Public Education and Outreach 31

8.1.5. Programs to Assess and Manage Distribution System Real Losses 32

8.1.6. Water Conservation Program Coordination and Staffing Support 32

8.1.7. Other Demand Management Measures 33

8.1.7.1. MWD’s Residential Landscape Transformation Program 33

8.1.7.2. Rebate Programs 33

8.1.7.3. U.S. Environmental Protection Agency’s (USEPA) WaterSense 33

8.1.7.4. Water Conservation Kits 34

9. Adoption, Submittal, and Implementation ............................................. 35

9.1. Notice of Public Hearing 35

9.2. Public Hearing and Adoption 35

9.3. Plan Submittal 35

9.4. Public Availability 35

9.5. Amending an Adopted UWMP or WSCP 36

10. References ......................................................................................................... 37 List of Tables
Table 1-1. Current and Projected Population 3
Table 1-2. SCAG Household and Employment Projections for Water Service Area 3 Table 2-1. Fiscal Year 2021-2025 Connections by Customer Class 6 Table 2-2. DWR 4-1R Actual Demands for Water, 2025, AFY 6 Table 2-3. DWR 4-5R Month Water Loss Audit Reporting 7
Table 2-4. Calculated Water Loss 9
Table 2-5. DWR 4-6R Progress Towards 2028 Water Loss Standard 9 Table 2-6. DWR 4-2R Projected Demands for Water Use, AFY 11 Table 2-7. DWR 4-3R Inclusion in Water Use Projections 11 Table 3-1. SB X7-7 2020 Target Progress 12
Table 4-1. DWR 6-1R Groundwater Pumped Last Five Years (AF) 15 Table 4-2. DWR 6-2R Wastewater Collected within Service Area in 2025 (AF) 17 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. iii
Table 4-3. DWR 6-3R Wastewater Treatment and Outcomes Within Service Area in 2025 (AF) 17 Table 4-4. DWR 6-8R Actual Water Supplies in 2025 (AF) 19 Table 4-5. DWR 6-9R Projected Water Supplies (AF) 20
Table 5-1. DWR 7-1R Basis of Water Year Data 23
Table 5-2. DWR 7-2R Normal Year Supply and Demand Comparison (AF) 25 Table 5-3. DWR 7-3R Single Dry Year Supply and Demand Comparison (AF) 25 Table 5-4. DWR 7-4R Multiple Dry Years Supply and Demand Comparison 26 Table 6-1. DWR 7-5 Five-Year Drought Risk Assessment (AF) 28 List of Figures
Figure 1-1. Service Area 2
Figure 2-1. Historical and Projected Demand 10
Figure 4-1. City of Pomona Projected Supply and Demand Comparison (AF) 21 Appendices
Part 4, Appendix D of the 2025 RUMWP contains Agency Supporting Information.

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. iv
Acronyms and Abbreviations
Acronym Description
AB1668 Assembly Bill 1668
AF Acre‑feet
AFY acre‑feet per year
AWWA American Water Works Association
City City of Pomona
CPUC California Public Utilities Commission
CRA Colorado River Aqueduct
CWC California Water Code
CWOL “Making Conservation a California Way of Life” Regulation DCP Drought Contingency Plan
DIM Dedicated Irrigation Meters
DMMs Demand Management Measures
DRA Drought Risk Assessment
DWR Department of Water Resources
DYYP Dry‑Year Yield Program
GEI GEI Consultants
GIS geographic information systems
GPCD gallons per capita per day
GRIP Groundwater Reliability Improvement Program
GRIP+ Groundwater Reliability Improvement Program (Plus) HECW high‑efficiency clothes washing
HVAC Heating, Ventilation, and Air Conditioning
IEUA Inland Empire Utilities Agency
LACSD Los Angeles County Sanitation Districts
MAF million acre‑feet
MWD Metropolitan Water District of Southern California
OSY Operating Safe Yield
PHET premium high‑efficiency toilets
PWRP Pomona Water Reclamation Plant
RHNA Regional Housing Needs Assessment
RUWMP Regional Urban Water Management Plan
SB606 Senate Bill 606
SBX7-7 Senate Bill 7 of Special Extended Session 7
SCAG Southern California Association of Governments
SJCWRP San Jose Creek Water Reclamation Plant
State Board State Resources Control Board
SWP State Water Project
TCE Trichloroethene
TVMWD Three Valleys Municipal Water District
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. v
USEPA United States Environmental Protection Agency
UWMP Urban Water Management Plan
UWUO Urban Water Use Objectives
WEWAC Water Education Water Awareness Committee
WRMP Water Resources Master Plan
WSCP Water Shortage Contingency Plan
WWTP Wastewater Treatment Plant
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. vi
Individual UWMP
This chapter describes information specific to the City of Pomona (City), including its supplies, demands, and water use efficiency programs. The information and analysis provided in this chapter supplements the regional information presented in Part 1 of the 2025 Regional Urban Water Management Plan (RUWMP) and is provided to fulfill the City of Pomona’s reporting requirements for 2025 under the UWMP Act.

The regional analyses described in Part 1 (Regional Context) of the 2025 RUWMP were conducted using a consistent analytical framework, assumptions, and methodologies that are directly applicable to the City of Pomona. The City relies on Part 1 of the RUWMP for the lay description, regional water supply availability, and the underlying technical methodology used to evaluate water supply reliability under normal, single dry-year, multiple dry-year, and five-year drought stress-test conditions.

The water supply reliability assessment and Drought Risk Assessment (DRA) applicable to the City’s Urban Water Management Plan (UWMP) are presented in plain language in Part 1 of the 2025 RUWMP , specifically within Chapter 5.

Building upon that regional foundation, the City-specific supply and demand comparisons are presented in the tables within this UWMP . Unless otherwise noted, the conclusions of the regional water supply reliability assessment and DRA are directly applicable to the City and satisfy the requirements of the Urban Water Management Planning Act and the 2025 UWMP Guidebook. A completed DWR UWMP Compliance Checklist for the City is provided in Part 4, Appendix D-1. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 1

1. System Description
This section describes the City’s water system, service area, population demographics, local climate, and land uses.

The City of Pomona was officially incorporated in January 1888 and became a charter city in March 1911.

The City provides water service to a majority of residential, commercial, and industrial customers within the City of Pomona, located in the eastern portion of Los Angeles County, approximately 35 miles from downtown Los Angeles. In addition, the City also provides water service to portions of La Verne, Claremont, Montclair, and Chino Hills. The City’s service area covers approximately 23 square miles and is bordered by several neighboring jurisdictions. To the north, it is bounded by the Cities of Claremont and La Verne; to the west, by the Cities of Industry, Walnut, and San Dimas; to the south, by Diamond Bar and Chino Hills; and to the east, by the City of Montclair. The City’s service area is shown in Figure 1-1.

The City has a seven-member City Council. Six Council members are elected representing six different Districts and serve four-year terms. The City Mayor is elected at large every four years. The City Manager is appointed by the City Council. Other City managerial positions are filled by the City Manager. The Water Resources Department is responsible for the operation and management of the City's water and sewer system.

Demand within the City’s service area is met through groundwater, local surface water, imported water, recycled water, and other non‑potable supplies. The City’s potable water system includes storage reservoirs, distribution pipelines, groundwater wells, booster pump stations, imported‑water turnouts, interagency connections, permitted treatment facilities, spreading grounds, and pressure‑regulating stations. The system includes approximately 6,000 fire hydrants and 421 miles of potable water pipelines.

The City’s primary supply is groundwater pumped from the Chino Basin and Six Basins. Additional local surface water is obtained from San Antonio Canyon and Evey Canyon. To supplement these supplies, the City purchases treated imported water from the Metropolitan Water District of Southern California (MWD) through Three Valleys Municipal Water District (TVMWD). 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 2

Figure 1-1. Service Area

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 3

1.1. Service Area
The City is a retail public water supplier that meets the definition of an urban water supplier with 30,446 municipal water service connections in 2024. The regional climate, which includes the City’s service area, is described in Part 1 Chapter 2 of the 2025 RUWMP .

1.1.1. Population, Demographics, and Socioeconomics
Estimates of population served by the City are based on the 2020 U.S. Census Bureau and the Southern California Association of Governments (SCAG) (Southern California Association of Governments, 2024). A geographic information systems (GIS) analysis of 2020 Census data was used to determine the City’s 2020 service area population, which was 150,777. The 2020 population and the number of residential connections served by the City in 2020 were used to derive a 2020 persons per residential connection factor of 5. This factor was then multiplied by the City’s number of residential connections in 2025 to estimate the 2025 population served by the City. To project the population served by the City from 2030 to 2050, average annual population growth rates from SCAG projections were applied to this 2025 estimate. A GIS analysis of SCAG projection data was used to determine the SCAG growth rate specific to the City’s service area. SCAG projected an increase in population from 2019 to 2035 averaging 0.38% per year and from 2035 to 2050 averaging 0.18% per year. Estimated current and projected populations of the City’s service area are included in Table 1-1.

Table 1-1. Current and Projected Population
Population Served 2025 2030 2035 2040 2045 2050
Total 155,836 158,803 161,770 163,270 164,770 166,270
The estimated 2025 and projected future number of households and employees within the service area were estimated using the same approach as population. SCAG projected an increase in households from 2019 to 2035 averaging 1.49% per year and from 2035 to 2050 averaging 0.35% per year. SCAG projected an increase in employment from 2019 to 2035 averaging 0.39% per year and from 2035 to 2050 averaging 0.08% per year. The estimated number of households and employees were determined by linear interpolation between SCAG projections for 2019, 2035, and 2050 as shown in Table 1-2.

Table 1-2. SCAG Household and Employment Projections for Water Service Area Category 2025 2030 2035 2040 2045 2050
Households 45,539 48,848 52,156 53,101 54,045 54,990
Employees 57,919 59,044 60,169 60,401 60,633 60,864
According to U.S. Census Bureau QuickFacts from 2024, the median household income in the City is $79,479. The City’s poverty rate is 14%. The City is 16% white alone, 10% Asian alone, 5% black alone, 23% two or more races, and 71% Hispanic or Latino. The average commute to work for workers at least 16 years of age is 31 minutes, which indicates that most jobs are local (United States Census Bureau, 2024). According to 2024 U.S. Census Bureau QuickFacts, the City’s population is made up of 13% of seniors (65 years and over), 22% of persons under 18 years, and 5% of persons under 5 years. (United 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 4

States Census Bureau, 2024). Table 1-2 provides employment and household projections for the City’s water service area based on SCAG GIS data intersected with the water service area.

1.1.2. Land Use
Per the Fiscal Year 2024-2025 Three Valleys Municipal Water District Assessed Service Area by Land Use, the City’s land use distribution by parcel count is as follows:
⚫ Single-Family Residential: 72%
⚫ Multi-Family Residential and Condominiums: 18%
⚫ Mobile Homes: <1%
⚫ Commercial: 4%
⚫ Churches: <1%
⚫ Industrial: 3%
⚫ Vacant Residential: 2%
⚫ Vacant Non-Residential: 1%
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 5

2. Water Use
This section describes the current and projected water uses within the City’s service area.

2.1. Water Use by Sector

2.1.1. Water Use Sectors Listed in Water Code
Water suppliers are required to identify water uses to the extent that records are available, for at least each of the water use sectors identified in CWC 10631(d) to assist in the water demand projections. The City primarily serves potable water to customers, though it does supply a small amount of recycled water. Recycled water uses are described in Section 4.5.

The City serves the following water uses:

Single Family Residential
Single family residential customers are typically on a lot with a free-standing building containing one dwelling unit that may include a detached secondary dwelling.

Multi-Family Residential
Multi-Family residential customers are typically multiple dwelling units within one building or several buildings within one complex.

Commercial
Commercial customers typically provide or distribute a product or service.

Government
Institutional water customers are typically public services, such as higher-education institutions, schools, courts, churches, hospitals, government facilities, and nonprofit research institutions.

Landscape Irrigation
City tracks the water use for landscape irrigation.

Losses
Distribution system water losses are the water losses from the point of water entry to the distribution system to the delivery point to the customer’s system. Water losses are discussed in Section 2.1.3.

The number of active connections is shown in Table 2-1. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 6

Table 2-1. Fiscal Year 2021-2025 Connections by Customer Class Customer Class 2021 2022 2023 2024 2025
Residential – Single Family 24,574 24,593 24,137 24,385 24,385 Residential – Multi-Family 2,466 2,484 2,487 2,492 2,492 Recycled 6 6 7 7 7
Government 417 416 391 400 400
Commercial 3,164 3,146 3,157 3,162 3,162
Irrigation 610 610 610 610 610
Total 31,237 31,255 30,789 31,056 31,056

2.1.2. Past and Current Water Use
The City serves potable water for a variety of uses, as summarized in Table 2-2. Over the past five years, the City served an average of 17,168 AFY of potable water. In 2025, 67% of the total potable water deliveries were to residential customers (47% to single-family accounts and 20% to multi-family accounts). Table 2-2 shows the annual volume of water used by each customer class for 2025.

Table 2-2. DWR 4-1R Actual Demands for Water, 2025, AFY Use Type Potable or Non-Potable (optional) 2025 Volume
Single Family Potable 8,160
Multi-Family Potable 3,557
Commercial Potable 3,223
Institutional Potable 1,187
Landscape Potable 1,392
Distribution System Water Loss Potable 779
Total 18,298

2.1.3. Distribution System Water Losses
Distribution system water losses are the physical potable water losses from the point of water entry to the distribution system to the point of delivery to the customer’s system. Water loss can result from aging infrastructure, leaks, seepage, theft, metering inaccuracies, data handling errors, and other causes.

Addressing water losses can increase water supplies and recover revenue. The City monitors its water loss and prepares an annual AWWA Water Audit to estimate the volume of water loss. The City has submitted all required water loss audits to the State, as shown in Table 2-3. Copies of the City’s recent AWWA audits are provided in Part 4, Appendix D-6.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 7

Table 2-3. DWR 4-5R Month Water Loss Audit Reporting
Public Water System ID # Reported in
DWR Table 2-1R Reporting Period Submitted to DWR Water Loss Audit Program
CA1910126 2020 Yes
2021 Yes
2022 Yes
2023 Yes
2024 Yes
DWR Notes:
2020 AWWA: Pomona City of _ CY2020_Version 5 - DM Updated 9-30-2021.xlsx 2021 AWWA: Pomona City of _ CY2021_Version 5.xlsx
2022 AWWA: CY2022_Pomona_Water Audit_v6..xlsx
2023 AWWA: CY2023_Pomona_Water Audit_ v6.0.xlsx
2024 AWWA: City of Pomona Water Loss Audit CY 2024 v6.0.xlsx CWC Section 10608.34 required the State Resources Control Board (State Board) to develop water loss performance standards for urban retail water suppliers to minimize water waste through system leaks.

Water loss performance standards were developed through a rulemaking that became effective in 2023.

Under the regulations, each supplier will be required to comply, by 2028, with an individualized volumetric water loss standard based on real loss, using the economic model developed by the State Board and the supplier’s own unique data. Real loss is the physical loss of water from water distribution systems, as opposed to apparent losses, which are revenue losses due to meter inaccuracies, billing errors or unauthorized consumption. A supplier’s baseline water loss is calculated as the average water loss from at least 3 of the 4 water loss audits from 2017 – 2020. The real water loss performance standard is based on gallons per service connection per day (gpscd), or gallons per mile of pipe per day (gpmd), depending on how the supplier reports real loss. Post-2028 compliance with volumetric water loss standards will be assessed every three years based on the average of the supplier’s real loss from the preceding three years, with an allowed variation of 5 gallons per connection per day above the supplier’s water loss standard. Apparent loss standards are equal to the baseline apparent loss and compliance is evaluated at the same time as compliance with the Real Water Loss Performance Standard.

Although the compliance period has not yet started, CWC Section 10631 (d)(3)(C) requires water suppliers to provide data in the UWMP to show whether the supplier met its State Board water loss performance standard.

Over the last five years, the City’s water losses have ranged from 4% to 12% when calculated as the difference between billed consumption and total production. To project the water loss component of future demands, the City assumed future water losses will be approximately 6% of total customer water use. Calculated water losses are shown in Table 2-4.

Based on data released by the State on January 30, 2026, the City’s baseline real water loss is 22.4 gpscd and the real water loss standard is 21.7 gpscd, and the apparent loss standard is the baseline of 13.1 gpscd. No reduction from the baseline is required to meet the water loss standard by 2028. As shown in Table 2-5, based on the most recent water loss audit from 2024, the City has not yet met the apparent 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 8

water loss performance standard, but is working toward that goal by 2028. Section 8.1.5 discusses City’s programs to assess and manage distribution system real loss. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 9

Table 2-4. Calculated Water Loss
Water Loss 2021 2022 2023 2024 2025
Calculated Water Loss 1,214 1,150 607 1,966 779 % Water Loss 6% 6% 4% 12% 4%
Table 2-5. DWR 4-6R Progress Towards 2028 Water Loss Standard Public System
ID # Reported
in Submittal
Table 2-1R
Did the
Water
Board
Calculate a
Water
Loss
Standard
for this
Public
System?
2028 Real
Water
Loss
Standard
per Unit
per day
Units for
Real
Water
Loss
Standard
Number of
Units
Volume of
Total Real
Water
Loss (from
AWWA
Water
Loss
Audit)
2025 or
Most
Recent
Year Real
Water
Loss per
Unit per
Day
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)
2025 or
Most
Recent
Year
Apparent
Water Loss
per Unit
per Day
CA1910126 Yes 21.7 gpscd 30,796 493 14.3 13.1 gpscd 30,796 923 26.8

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 10

2.2. Projected Water Use
As shown in Figure 2-1, total water demand has trended downward since 2015, which is most likely due to permanent conservation in response to droughts, state mandated water use reduction targets, more efficient appliances and plumbing, and conservation efforts made by the City and its customers. The City anticipates that demands may continue in alignment with historic patterns. Therefore, demands used for the purposes of this UWMP are assumed to reduce by 2 gallons per capita per day (GPCD) per five-year planning period from 2025, which is 105 GPCD. This results in 103 GPCD in 2030, declining approximately 2 GPCD every five years until it reaches 95 GPCD in 2050. Population projections as described in Section

1.1.1 are applied to these GPCD values to project future demands. The assumed future water loss of 6% described in the previous section was applied to the subtotal of demand for all connection types to estimate future water losses. Table 2-6 presents the projected demand by customer type through 2050 for this UWMP .

Figure 2-1. Historical and Projected Demand

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 11

Table 2-6. DWR 4-2R Projected Demands for Water Use, AFY Use Type Additional
Description
Level of
Treatment
When
Delivered
Projected
Water
Use 2030
Projected
Water
Use 2035
Projected
Water Use
2040
Projected
Water
Use 2045
Projected
Water Use
2050
Single Family Potable 8,178 8,164 8,075 7,986 7,897
Multi-Family Potable 3,529 3,523 3,484 3,446 3,408
Commercial Potable 3,062 3,057 3,024 2,991 2,957
Institutional Potable 1,100 1,098 1,086 1,074 1,063
Landscape Potable 1,248 1,245 1,232 1,218 1,205
Distribution System
Water Losses
Potable 1,157 1,155 1,143 1,130 1,117
Total 18,273 18,242 18,043 17,845 17,647
Table 2-6 and Table 2-7 satisfy the requirement to include anticipated water conservation savings when developing future demand projections for the next 25 years since they reduce by 2% GPCD per year from 2025. The City is complying with and planning for UWUO standards as described in Sections 3 and 8.

Senate Bill 1087 requires that water use projections in an Urban Water Management Plan (UWMP) include projected water use associated with single family and multi-family residential housing for lower income households, as identified in the housing elements of any city, county, or city and county within the supplier’s service area. The Regional Housing Needs Assessment (RHNA) establishes housing needs for each jurisdiction over the applicable planning period. SCAG adopted the 6th Cycle RHNA Allocation Plan, which covers the planning period from October 2021 through October 2029 (Southern California Association of Governments (SCAG), March 2021). SCAG’s population and household projections inform the RHNA Allocation Plan and are used in the determination and allocation of housing needs, including lower income housing, for individual jurisdictions. The growth projections in this UWMP are based on SCAG projections for the service area and therefore also incorporate the lower income housing projections. The projected demands in this UWMP represent water use from all future growth and are inclusive of water use for lower income households.

Table 2-7. DWR 4-3R Inclusion in Water Use Projections
Question Yes or No
Are Future Water Savings Included in Projections? Yes
Are Lower Income Residential Demands Included in Projections? Yes

2.3. Climate Change Considerations
A topic of growing concern for water planners and managers is climate change and the potential impacts it could have on California’s future water supplies. A recent Climate Change Vulnerability Assessment utilizing data from DWR and 20 global climate models suggests that a changing climate will have multiple effects on the Region. Adaptation and mitigation measures will be necessary to account for these effects.

Part 1, Chapter 2 of the 2025 RUWMP includes an assessment of the potential impacts of climate change.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 12

3. SB X7-7 Compliance & Future Water Use Efficiency
Requirements
This section describes compliance with the Water Conservation Act of 2009, also known as Senate Bill 7 of Special Extended Session 7 (SBX7-7). The section demonstrates compliance with the 2020 SBX7-7 target and discusses future water use efficiency requirements.

3.1. Compliance and Future Water Use Efficiency Requirements SBX7-7 was incorporated into the UWMP Act in 2009 and required that all water suppliers increase water use efficiency with the overall goal to decrease per-capita water consumption within the state by 20% by the year 2020.

SBX7-7 required DWR to develop certain criteria, methods, and standard reporting forms through a public process that water suppliers could use to establish their baseline water use and determine their water conservation targets. SBX7-7 and DWR's Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use (DWR, March 2021) specify methodologies for determining the baseline water demand, 2015 interim urban water use target, and the 2020 urban water use target for the City as described in the 2020 UWMP . This section also demonstrates that the City achieved its 2020 water use target.

Table 3-1 below establishes the City’s 2020 actual and 2020 target GPCD. As shown, the City met its 2020 target. Most recently, in 2025, the water use was 105 GPCD, which is well below the 2020 target of 147 GPCD.

Table 3-1. SB X7-7 2020 Target Progress
2020 Target GPCD 2020 Actual GPCD Did Supplier Achieve Target? 147 113 Yes
New water use efficiency standards from the “Making Conservation a California Way of life Regulation” (CWOL Regulation) supersede SBX7-7 standards. In 2018, two policy bills were enacted by the California Legislature, Assembly Bill 1668 (AB1668, Friedman) and Senate Bill 606 (SB606, Hertzberg), collectively referred to as the “2018 Water Conservation Legislation.” Based on the 2018 Water Conservation Legislation, related legislation, and subsequent adoption of the CWOL Regulation, each urban retail water supplier must comply with its UWUO. DWR and the State Board have developed a reporting framework for calculating the UWUO and compliance annually with efficiency standards becoming increasingly stringent through 2040.

The demand projections in this UWMP are based on the City meeting its estimated future UWUO, as described in Section 2.2 in order to plan and implement necessary demand management measures (DMMs) (described in Section 8) to support meeting the UWUO. DMMs and UWUO compliance planning enhance resiliency for drought and other water shortage conditions as described in Sections 5, 7, and 8. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 13

4. Water Supply
The City’s primary sources for water supply include treated imported water purchased from MWD through TVMWD, groundwater pumped from Chino Basin, Spadra Basin, and Six Basins, local surface water from San Antonio Creek, and recycled water purchased from the Los Angeles County Sanitation Districts (LACSD). The City’s main source of water supply is groundwater pumped from the Chino Basin.

More information about local surface water and groundwater basins is included in Part 1 Chapter 3 of the 2025 RUWMP .

4.1. Purchased or Imported Water
The City purchases treated imported water from MWD through TVMWD. MWD imports water from the Colorado River through the Colorado River Aqueduct (CRA), owned and operated by MWD, and the State Water Project (SWP), which utilizes the CRA for transmission to Southern California. Water delivered to TVMWD’s member agencies can receive treated imported water from MWD’s Weymouth Treatment Plant located in the City of La Verne or from TVMWD at its Miramar Water Treatment Plant located in the City of Claremont.

The City’s treated imported water supplies from MWD, through TVMWD, may be impacted during a multi-year drought or other conditions which limits MWD from delivering sufficient water supplies to its member agencies, and consequently to the City. A description of this supply and its reliability is provided in Part 1, Chapter 3 and Part 1, Chapter 5 of the 2025 RUWMP.

4.2. Groundwater
The City holds groundwater rights in three regional groundwater basins: Chino Basin, Six Basins, and Spadra Basin, though the City does not currently extract from the Spadra Basin. All three basins have been adjudicated and are managed for long-term sustainability, as discussed further in Part 1 Chapter 3 of the RUWMP.

4.2.1. Chino Basin
The City currently produces groundwater from the Chino Basin, which is a sub-basin of the Upper Santa Ana Valley Groundwater Basin and is managed by the Chino Basin Watermaster.

The Chino Basin Judgment originally established a Safe Yield for the Chino Basin of 140,000 AFY . Pursuant to the most recent Safe Yield reset effective in 2020, the Safe Yield in the Chino Basin is currently 131,000 AFY (July 1 to June 30). The Safe Yield is recalculated every 10 years and is defined in the Chino Basin Judgment as “the long-term average annual quantity of ground water (excluding replenishment of stored water but including return flow to the Basin from use of replenishment or stored water) which can be produced from the Chino Basin under conditions of a particular year without causing an undesirable result”. The Chino Basin Judgment’s allocation of the Safe Yield includes three separate Pools: (1) the “Overlying Agricultural Pool”; (2) the “Overlying Non-Agricultural Pool”; and (3) the 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 14

“Appropriative Pool”. At this juncture, the Chino Basin Watermaster is in the process of a Safe Yield reevaluation and has provided an estimated Safe Yield of 117,500 AFY .

The City’s percent share of the Operating Safe Yield (OSY) is 20.454%.

4.2.2. Six Basins
The City also produces groundwater from Six Basins. Six Basins is a group of six interconnected groundwater basins that underlie areas of the Cities of Claremont, La Verne, Pomona, and Upland, and surrounding unincorporated areas of Los Angeles and San Bernardino Counties. The City currently produces groundwater from 9 wells located in the Upper Claremont Heights, Lower Claremont Heights, and Pomona Basins.

A court-appointed Watermaster is responsible for the administration of the Six Basins Judgment.

Pursuant to the Judgment, the safe yield of the Six Basins is 19,300 AFY , which is defined as the amount of water that can be produced from the parties on an annual basis to ensure long-term, sustainable groundwater production. The production, replenishment, and recovery of the Live Oak and Ganesha Basins (collectively referred to as Two Basins) are reserved solely for the City of La Verne and are not subject to any groundwater production limitations, provided that production by the City of La Verne does not substantially injure the rights of any other Six Basin parties. However, the Canyon, Upper Claremont Heights, Lower Claremont Heights, and Pomona Basins (collectively referred to as Four Basins) are subject to individual OSYs determined annually by the Six Basins Watermaster.

The City’s percent share of the OSY is 20.798%. As described in Part 1, Chapter 3, the City is allowed to carry over portions of its unused Six Basins annual pumping rights for up to one year. Carryover rights are limited to a maximum of 25% of the City’s share of the OSY. However, any amount extracted in excess of the water rights will then be deducted from the following year’s water rights.

4.2.3. Spadra Basin
The City currently does not produce groundwater from the Spadra Basin. Groundwater produced from the Spadra Basin for potable water uses requires treatment or blending prior to use to comply with SWRCB-DDW drinking water standards. As a result, groundwater produced from the Spadra Basin is used primarily for non-potable overlying uses by local water agencies. This basin is unadjudicated and is discussed further in Part 1, Chapter 3 of the RUWMP .

Table 4-1 summarizes the City’s actual groundwater production over the past five years. Pumping volumes fluctuate annually based on total system demand, the availability of surface water, and local hydrological conditions.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 15

Table 4-1. DWR 6-1R Groundwater Pumped Last Five Years (AF) Groundwater Type Location or Basin
Name 2021 2022 2023 2024 2025
Alluvial Basin Chino Basin 9,182 10,159 10,189 10,449 9,796 Alluvial Basin Six Basins 3,447 3,120 2,075 3,066 3,792 Total 12,629 13,279 12,264 13,515 13,588

4.3. Surface Water
The City has surface water facilities which are located near the base of the San Antonio Canyon and Evey Canyon watersheds that discharge runoff from the San Gabriel Mountains into local spreading grounds through the San Antonio Creek. The amount of surface water runoff that is discharged to the San Antonio Creek is dependent on local precipitation and snowmelt from the San Gabriel Mountains. The City owns the water rights to 40% of the first 8.09 MGD (9,055 AFY) of flow from the San Antonio Creek and owns the rights to receive all the water from the Evey Canyon. The City has the infrastructure to produce up to 4,000 AFY of that surface water for supply.

The City’s surface water facilities include: (1) an intake/weir structure at the San Antonio Canyon; (2) the City’s Pedley Filtration Plant (PFP) located in the City of Claremont; and (3) the Canon Waterline that connects the San Antonio Canyon and Evey Canyon watersheds to the PFP . The intake/weir structure at the San Antonio Canyon distributes the flow between the San Antonio Water Company and the City (i.e. 40%). From there the City’s water travels in a pipeline south where water from Evey Canyon is added. A Canon Waterline transfers the raw surface water collected from both watersheds to the PFP for treatment. At the PFP , the waterline discharges into a diversion structure which transfers all instantaneous flows less than or equal to 4 MGD into the PFP. Flows greater than 4 MGD are diverted to the Pomona Spreading Grounds, located adjacent to the PFP .

4.4. Stormwater
The City does not directly use stormwater to meet its water demands.

4.5. Wastewater and Recycled Water
Wastewater generated by the City is collected within the City’s local sewer collection system and treated by LACSD. The City provides sewer service to an area of approximately 14,680 acres within the City limits and approximately six acres outside of the City limits. Approximately 2,000 acres in the City drain to other serving entities or currently produce no sewage.

The City’s local sewers tie into LACSD’s regional trunk sewers – which convey flows to the Pomona Water Reclamation Plant (PWRP) and the LACSD Joint Water Pollution Control Plant (JWPCP) – at approximately 200 locations within the City. The percentage of flows to each plant is not specified.

The City currently has the right to purchase and sell two-thirds of PWRP’s recycled water. PWRP has a capacity to treat 15 MGD of wastewater and produces an average of 9 MGD of recycled water. Based on 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 16

this average production rate, the City has approximately 6 MGD available for beneficial reuse. The estimated amount of wastewater collected by the City in 2025 was approximately 2,500 MG (about 7,672 AF).

Table 4-2 and Table 4-3 show existing wastewater collection and treatment at the Pomona Water Reclamation Plant.

The City also has seven non-potable wells available for use in its recycled water system. The City currently provides recycled water to customers inside and outside of the City’s service area. The City’s distribution system is located entirely within the City’s municipal boundaries where it delivers recycled water to two booster pumping stations that serves the following locations outside of the City’s municipal boundaries:
⚫ California State Polytechnic University (Cal Poly): This pump station is located southwest of the interchange of the 10 Freeway and the 57 Freeway. Recycled water is boosted to a recycled water reservoir on the western part of the campus through a pipeline owned and operated by the university. The University provides recycled water to the Forest Lawn Memorial Park in Covina.
⚫ Bonelli Park: This pump station is located south of the 10 Freeway and west of the 57 Freeway.

Recycled water is boosted to a recycled water reservoir in Bonelli park, serving Bonelli Park, the East Shore Recreational Vehicle Park, and the Mountain Meadows Golf Course.

The City’s recycled water system facilities are either City-owned or customer-owned. Active City-owned facilities include the PWRP booster pump station, a 0.7 MG reservoir, and 3 MG reservoir. Customer- owned facilities include reservoirs and booster pump stations owned and operated by California State Polytechnic University, Pomona; Bonelli Park; and Caltrans. The City’s recycled water system operates primarily to distribute recycled water from PWRP to its customers. Historically, recycled water use within the City’s service area has been used mainly for irrigation, with some commercial and industrial users.

4.5.1. Potential, Current, and Projected Recycled Water Uses Currently, the City delivers recycled water to several locations for use in agricultural and landscape irrigation, ornamental plant irrigation, impoundment, and athletic field irrigation. The City’s 2009 Recycled Water Master Plan identifies potential recycled water users (City of Pomona, 2009). The City is currently preparing a “Water, Sewer and Recycled Water Strategic Plan” to modify the recycled water system to include projects pending additional funding.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 17

Table 4-2. DWR 6-2R Wastewater Collected within Service Area in 2025 (AF) Wastewater Collection Recipient of Collected Wastewater Name of Wastewater
Collection Agency
Wastewater Volume
Metered or Estimated
Volume of Wastewater Collected
from UWMP Service Area 2025
Name of Wastewater Treatment
Plant (WWTP) and Place ID Number
Is WWTP Located
Within UWMP Area?
LACSD Metered 7,672 PWRP, Place ID 250700 Yes
Total 7,672
Table 4-3. DWR 6-3R Wastewater Treatment and Outcomes Within Service Area in 2025 (AF) Wastewater
Treatment Plant
Name and Place ID
Number
Does This
Plant Treat
Wastewater
Generated
Outside the
UWMP
Service
Area?
2025 Volume of
Wastewater
Received from
UWMP Service
Area
(As Reported in
Submittal Table
6-2)
Total 2025
Volume of
Water
Treated
Treatment
Level
2025
Outcomes
of Treated
Wastewater
Recycled
within
Service
Area
2025
Outcomes
of Treated
Wastewater
Recycled
Outside of
Service
Area
2025
Outcomes of
Treated
Wastewater
Effluent
Discharge
that is not a
Permitted
Recycled
Water Use
2025
Outcomes
of Treated
Wastewater
Instream
Flow Permit
Required
2025
Outcomes
of Treated
Wastewater
Delivered to
Another
Entity for
Additional
Treatment
Pomona Water
Reclamation Plant,
Place ID 250700
YES 7,672 4,987 Tertiary 1,423 3,564
Total 1,423 3,564

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 18

4.6. Water Exchanges and Transfers
The City is currently able to exchange surface and/or groundwater with the following utilities:
⚫ City of Upland: Groundwater between Six Basins and Chino Basins -- Existing groundwater agreements include the “bucket for bucket” exchanges with the City of Upland. ⚫ San Antonio Water Company: Surface water - Canon Water Line diverted and exchanged for 110% of groundwater credit in the Six Basins.

In addition, the City participates in MWD’s Dry-Year Yield Program (DYYP). The DYYP is a groundwater storage and recovery program where supplemental water is stored in the Chino Basin during surplus years and could be recovered in-lieu of imported water from MWD through Inland Empire Utilities Agency (IEUA). The DYYP allows maximum use of imported water supplies available during wet years and stored groundwater in the Chino Basin during dry years. The DYYP can store up to 100,000 AF with maximum replenishment of 25,000 AFY and maximum extraction of 33,000 AFY . Based on the Chino Basin Watermaster 2024/2025 Assessment Package, during FY 2023-2024, there was 45,908.2 AF within the DYYP account. The agreement that authorized the DYYP will expire in 2028.

Water rights under the Six Basins Judgment can be transferred by assignment, sale, contract, or lease so long as such transfers meet the requirements of the Judgment. However, a Party’s right to produce, store or recover groundwater in the Four Basins Area may not be transferred, exchanged or exercised in the Two Basins Area. In addition, a Party's right to produce, store or recover groundwater in the Two Basins Area may not be transferred, exchanged or exercised in the Four Basins Area. The City is able to utilize the transfer opportunities available for Six Basins water when necessary.

4.7. Future Water Projects
As part of the TVMWD Water Resources Master Plan (WRMP) and Drought Contingency Plan (DCP) with the member agencies, the City is currently pursuing several projects to increase water supply reliability (TVMWD, 2025). Future projects include:
⚫ The City is planning to implement groundwater quality improvement measures, including the Anion Exchange Plant and enhancements to Reservoir 5. The project includes the installation of new extraction wells, enhancement of well efficiency, upgrades to aging infrastructure, and groundwater treatment. This project is expected to increase overall supply by approximately 5,300 AF.
⚫ Reservoir 6 roof replacement, which upgrades aging infrastructure.

Four regional water supply projects were also identified in the WRMP and DCP effort through collaboration with TVMWD, member agencies, and regional stakeholders. These regional projects, described in Part 1, Chapter 3, are intended to enhance overall supply reliability for the region. ⚫ Project 1: External Partnership with CVWC – Main Basin ⚫ Project 2: TVMWD Groundwater Reliability Improvement Program (GRIP) 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 19

⚫ Project 3: TVMWD Storing Water in Main San Gabriel Basin (GRIP+) ⚫ Project 4: TVMWD–Pomona Chino Basin Conjunctive Use Exchange As development progresses and increased demands are placed on the system, the City will determine which projects to implement.

4.8. Summary of Existing and Planned Sources of Water
The City’s water supply is comprised of treated imported water, groundwater, local treated surface water, and recycled water. The volume of water utilized from each source in 2025 is summarized in Table 4-4, and projected supply is summarized in Table 4-5.

Table 4-4. DWR 6-8R Actual Water Supplies in 2025 (AF)
Water Supply Additional Detail on
Water Supply
2025 Actual
Volume
2025 Potable or
Non-Potable
(optional)
2025 Total
Entitlement
(optional)
Groundwater (not
desalinated) Chino Basin 9,796 Potable
Groundwater (not
desalinated) Six Basins 3,792 Potable
Surface Water San Antonio Creek 1,683 Potable
Recycled Water Pomona Water
Reclamation Plant 1,849 Non-Potable
Purchased or Imported
Water
Metropolitan Water
District – TVMWD 3,027 Potable
Total – Potable 18,298
- Total 20,147 -
Supply Projection Methodology
To project future water supplies accurately and conservatively, the City, in coordination with TVMWD, evaluated supply projection methodologies. Rather than projecting supplies based on maximum legal entitlements or absolute physical extraction capacity, the City opted to utilize a "Real Water" (Utilization- Based) approach. This approach grounds future projections in empirical operational reality. The methodology utilized a baseline representing the City’s average local supply utilization over the most recent five-year period (2021–2025), which was 20,327 acre-feet per year (AFY). This baseline smoothed out historically dry years (e.g., 2021) and historically wet years (e.g., 2023).

To calculate the projected supplies shown in Table 4-5, the following steps were applied:

1. Climate Change Adjustments: Specific climate change vulnerability factors, derived from TVMWD's 2024 Climate Vulnerability Analysis, were applied to the 2021-2025 baseline local agency supplies (Chino Basin, Six Basins, and Spadra Basin groundwater, and San Antonio Creek surface water) to forecast anticipated local yields through 2050. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 20

2. Imported Water Reliance: The projected local supplies were then compared against the City’s projected demand. Any projected unmet demand is assumed to be fulfilled by imported water purchases from TVMWD.

Potable and Non-Potable System Accounting
Because the City operates physically separate potable and non-potable distribution systems, the total projected supplies shown in Table 4-5 reflect an aggregation of both systems. To accurately reflect this separation for planning purposes, projected recycled water and non-potable groundwater supplies are scaled to strictly equal the projected non-potable demands. The remaining supplies are dedicated exclusively to the potable system. There is no crossover of non-potable supplies to meet potable demands, maintaining a transparent and accurate projection of supply sufficiency for each distinct system.

As shown in Table 4-5 and Figure 4-1, the City’s reliance on local groundwater and surface water is projected to decrease slightly over time under a climate change planning scenario that models potential impacts to local hydrology. Under this specific scenario, imported water purchases from TVMWD are projected to increase modestly to balance the City’s overall supply portfolio and meet customer demands. It is important to note that these projections are intended for long‑term vulnerability planning purposes only; they do not incorporate future adaptation or mitigation strategies currently being developed or implemented at the regional level. Future actions, such as those identified in the DCP , are specifically designed to reduce or offset these potential climate‑related impacts to local supplies.

Table 4-5. DWR 6-9R Projected Water Supplies (AF)
Water Supply Additional Detail on
Water Supply 2030 2035 2040 2045 2050
Groundwater
(not desalinated) Chino Basin 10,050 9,970 9,800 9,555 9,239 Groundwater
(not desalinated) Six Basins 3,216 3,190 3,136 3,057 2,956 Surface Water San Antonio Creek 1,691 1,674 1,649 1,616 1,576 Recycled Water Pomona Water
Reclamation Plant 1,874 1,874 1,874 1,874 1,874
Purchased or
Imported Water
Metropolitan Water
District – TVMWD 3,315 3,408 3,458 3,617 3,876
Total – Potable 18,273 18,242 18,043 17,845 17,647
Total – All 20,147 20,116 19,917 19,719 19,521
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 21

Figure 4-1. City of Pomona Projected Supply and Demand Comparison (AF)

4.9. Energy Intensity of Water Supplies
Reporting water energy intensity has many benefits for water utilities and their customers including:
⚫ 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.
⚫ Potential opportunities for receiving energy efficiency funding for water conservation programs. ⚫ Informing climate change mitigation strategies.
⚫ Benchmarking of energy use at each water acquisition and delivery step and the ability to compare energy use among similar agencies.

In 2025, the City consumed approximately 470 kWh of energy for water facilities per AF of water delivered.

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 22

5. Water Service Reliability Assessment
This section considers the City’s water supply reliability during normal years, single dry years, and up to five consecutive dry water years. The supply reliability assessment discusses factors that could potentially limit the expected quantity of water available from the City’s current source of supply through 2050.

5.1. Constraints on Water Sources
While the City maintains a highly reliable water portfolio, its supply sources are subject to various environmental, regulatory, and infrastructural constraints. A comprehensive analysis of regional water supply constraints is provided in Part 1, Chapter 3 and Part 1, Chapter 5 of the 2025 RUWMP .

For the City of Pomona specifically, the primary constraints on water sources include:
⚫ Imported Water Supply Reductions: As detailed in Part 1, Chapter 3, MWD typically buffers statewide supply cuts using its massive regional storage portfolio. However, during severe multi- year droughts when State Water Project (SWP) and Colorado River allocations are drastically reduced by the State, the City may face constraints on the volume of imported water available from MWD through TVMWD. To offset these potential imported water constraints, the City actively manages its diverse portfolio, relying on its local groundwater reserves, recycled water, and programs like MWD's Dry-Year Yield Program (DYYP) in the Chino Basin. ⚫ Groundwater Quality: Contaminants such as volatile organic compounds (VOCs), nitrate, perchlorate, and arsenic in the local groundwater basins (Chino, Six Basins, and Spadra Basins) can force the City to temporarily remove active extraction wells from service. To mitigate this constraint and maximize local supply reliability, the City is actively investing in wellhead treatment and infrastructure upgrades, such as the 4.7construction of wellhead treatment at Well 36 in the Chino Basin.
⚫ Climate Change Impacts on Surface Water: The City's local surface water supply from San Antonio Creek and Evey Canyon is dependent on local precipitation and snowmelt from the San Gabriel Mountains. As identified in Part 1, Section 2.5, this source is highly susceptible to climate-driven volatility, including shorter rainy seasons, reduced snowpack, and severe post- wildfire turbidity, which can temporarily halt treatment operations at the City's PFP .

5.2. Year Type Characterization
In general, groundwater and recycled water are less vulnerable to seasonal and climatic changes than surface water (i.e., local mountain runoff and imported supplies). The Chino Basin Watermaster and Six Basins Watermaster actively monitor groundwater levels and implement supplemental recharge to maintain the long-term sustainability of the City's primary local groundwater sources. Further discussion of regional water resource management is included in Part 1 Chapter 3 of the RUWMP. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 23

Because the City's baseline years are a mix of different hydrologic conditions, it is important to note how the City's supply strategy adapts to dry years. The City's primary local groundwater supplies, the Chino Basin and the Six Basins, have variable OSYs that may decline during dry periods. However, under the respective adjudication frameworks for these basins, the City can legally and physically continue to produce the water it needs to meet elevated dry-year demands by paying replenishment or replacement water assessments for any production that exceeds its rights. As a result, the City's operational supply strategy is not significantly different in dry years compared to normal years. The changes in the City's projected baseline supply over time are primarily driven by long-term climate change factors (as detailed in Section 4.8) and planned infrastructure projects.

Per UWMP requirements, the City has evaluated reliability for an average year, single dry year, and a five consecutive dry year period. The UWMP Act defines these years as:
⚫ Normal Year: This condition represents the water supplies a supplier considers available during normal conditions. This could be a single year or averaged range of years that most closely represents the average water supply available.
⚫ Single Dry Year: The single dry year is recommended to be the year that represents the lowest water supply available.
⚫ Five-Consecutive Year Drought: The driest five-year historical sequence for the Supplier, which may be the lowest average water supply available for five years in a row.

To characterize these year types, the City evaluated historical supply and demand data. For the purposes of this 2025 UWMP , the City established a "Normal Year" baseline using the average annual supply and demand from 2021 through 2025.

Because water demand in the City typically increases during dry years due to elevated outdoor irrigation needs, the "Single Dry Year" and "Five-Year Drought" scenarios are modeled using historical years where production peaked to meet elevated drought demands. Table 5-1 summarizes the base years utilized for this analysis and the corresponding volume of water available/utilized as a percentage of the average year.

Table 5-1. DWR 7-1R Basis of Water Year Data
Year Type Base Year (FY) Volume Available
(AF) % of Average Supply
Average Year 2021-2025 20,327 100%
Single-Dry Year 2021 22,029 108%
Consecutive Dry Years 1st Year 2018 21,276 105%
Consecutive Dry Years 2nd Year 2019 19,782 97%
Consecutive Dry Years 3rd Year 2020 21,174 104%
Consecutive Dry Years 4th Year 2021 22,029 108%
Consecutive Dry Years 5th Year 2022 20,981 103%
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 24

5.3. Water Service Reliability
The results of the reliability assessment are summarized below.

As established in Section 4.8 and Part 1, Chapter 5, the City utilized the "Real Water" (Utilization-Based) methodology to project its future supplies. Under this operational approach, the City projects its local groundwater, local surface water, and recycled water supplies based on historical averages adjusted for climate change. Any remaining unmet demand is fulfilled by purchasing imported water from TVMWD.

The City’s projected "Normal Year" water demands over the next 25 years were developed using a demand-per-connection approach as discussed in Section 4.8 and Section 5.2. This approach utilizes a baseline period of 2025 to approximate normal demand patterns, projects future connections based on SCAG growth rates and incorporates anticipated reductions due to passive conservation and compliance with the new "Making Conservation a California Way of Life" (CWOL) regulatory framework.

To estimate projected demands during drought conditions, the City utilized a historical ratio methodology. Because water demand in Southern California typically increases during hot, dry periods due to elevated outdoor irrigation needs, the City analyzed the ratio of total water utilized during historical dry periods compared to a historical average year.

Based on the City's operational data, the historical average year baseline was established using the five- year period of FY 2021–2025 (averaging 20,327 AF).
⚫ Single Dry Year Scaling: The ratio of water utilized during the historical single dry year of FY 2021 (22,029 AF) to the historical average (20,327 AF) yielded a scaling factor of 108%. This 108% factor was applied to the projected normal year demands to estimate the City's projected water demands during future single dry years.
⚫ Five-Year Drought Scaling: To estimate demands during a five-consecutive-year drought, the City utilized the historical drought sequence from FY 2018 through FY 2022. The ratio of water utilized in each of these years (21,276 AF, 19,782 AF, 21,174 AF, 22,029 AF, and 20,981 AF, respectively) compared to the historical average yielded scaling factors of 105%, 97%, 104%, 108%, and 103% for years one through five of the drought sequence, respectively. These factors were applied to the projected normal year demands to forecast future multi-year drought demands.

Because TVMWD and MWD have demonstrated 100% supply reliability to meet wholesale demands through 2050 (supported by MWD's 2025 UWMP supply reliability analysis (MWD, 2026)), the City's total supply is projected to perfectly meet its total projected demand across all hydrologic scenarios.

Consequently, the difference between supply and demand in the tables below is zero, reflecting a fully reliable water portfolio through the 2050 planning horizon.

Potable and Non-Potable System Accounting
To accurately reflect the separation of the City's potable and non-potable distribution systems, the supply and demand totals presented in the reliability tables below assume that projected recycled water 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 25

supply strictly equals recycled water demand for non-potable uses. All other water supplies listed are utilized exclusively to meet potable demands. There is no crossover of non-potable supplies to meet potable demands; as such, the demonstrated supply reliability applies independently and sufficiently to both the potable and non-potable systems.

Table 5-2, *Note: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in Table 2-6. The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in Table 4-5.

Table 5-3, and *Note: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in Table 2-6. The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in Table 4-5. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 26

Table 5-4 summarize the City’s projected water supplies and demands over the next 25 years in five-year increments. These tables demonstrate the City can reliably meet elevated water demands during normal years, single dry years, and five-consecutive-year drought periods over the next 25 years.

Table 5-2. DWR 7-2R Normal Year Supply and Demand Comparison (AF) Totals 2030 2035 2040 2045 2050
Supply totals 20,147 20,116 19,917 19,719 19,521
Demand totals 20,147 20,116 19,917 19,719 19,521
Difference 0 0 0 0 0
*Note: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in Table 2-6. The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in Table 4-5.

Table 5-3. DWR 7-3R Single Dry Year Supply and Demand Comparison (AF) Totals 2030 2035 2040 2045 2050
Supply totals 21,834 21,801 21,585 21,370 21,156
Demand totals 21,834 21,801 21,585 21,370 21,156
Difference 0 0 0 0 0
*Note: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in Table 2-6. The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in Table 4-5. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 27

Table 5-4. DWR 7-4R Multiple Dry Years Supply and Demand Comparison Year Totals 2030 2035 2040 2045 2050
First Year Supply Totals 21,087 21,055 20,847 20,640 20,432 Demand Totals 21,087 21,055 20,847 20,640 20,432
Difference 0 0 0 0 0
Second Year Supply Totals 19,607 19,577 19,383 19,190 18,998 Demand Totals 19,607 19,577 19,383 19,190 18,998
Difference 0 0 0 0 0
Third Year Supply Totals 20,986 20,954 20,747 20,541 20,334 Demand Totals 20,986 20,954 20,747 20,541 20,334
Difference 0 0 0 0 0
Fourth Year Supply Totals 21,834 21,801 21,585 21,370 21,156 Demand Totals 21,834 21,801 21,585 21,370 21,156
Difference 0 0 0 0 0
Fifth Year Supply Totals 20,795 20,763 20,558 20,353 20,149 Demand Totals 20,795 20,763 20,558 20,353 20,149
Difference 0 0 0 0 0
*Note: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in Table 2-6. The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in Table 4-5. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 28

6. Drought Risk Assessment
The Drought Risk Assessment (DRA) is an analysis required for the 2025 UWMP, with a focus on the five- year consecutive drought scenario beginning in 2026. While Section 5 evaluated long-term reliability through 2050, the DRA serves as an immediate stress test, focusing specifically on the five-year period from 2026 through 2030. The purpose of this assessment is to determine if the City anticipates any supply shortages in the immediate future that would necessitate triggering mandatory demand reduction measures outlined in the Water Shortage Contingency Plan.

6.1. Data, Methods, and Basis for Water Shortage Conditions To conduct the DRA, the City utilized the same "Real Water" supply methodology and historical drought scaling factors detailed in Section 4.8 and Section 5. The assessment simulates a severe, five- consecutive-year drought mirroring the hydrology of Fiscal Years 2018 through 2022.

Because hot, dry weather drives increases in outdoor irrigation, the City's unconstrained demands are projected to scale up significantly during this period (up to 108% of average baseline demand, as established in Section 5.3). The DRA tests whether the City's local groundwater, local surface water, recycled water, and imported water portfolios can sustain these elevated demands over the next five years without natural replenishment.

6.2. DRA Water Source Reliability
The City's near-term reliability is highly secure due to the active management of the Chino Basin, Six Basins, and Spadra Basin, the consistent utilization of recycled water, and the unprecedented storage reserves held by its wholesale providers.

Entering the 2026–2030 DRA period, MWD holds nearly 4 million acre-feet (MAF) of water in regional storage, which is a near-record high. MWD’s 2025 UWMP DRA modeling confirms that even if the SWP and CRA experience five consecutive years of severe constraint, MWD has sufficient stored reserves to meet all wholesale member agency demands without shortage allocations through 2030. Consequently, TVMWD can reliably supply the City with imported water to cover any deficits caused by constrained local groundwater production.

6.3. Total Water Supply and Use Comparison
Table 6-1 details the DRA for the 2026–2030 period. As demonstrated in the table, the City's projected supplies are sufficient to fully and consistently meet the elevated, unconstrained demands for every year of the five-year drought sequence.

Because the City anticipates a supply surplus (a difference of zero) across all five years of the near-term drought scenario, the City does not currently project a need to implement mandatory, extraordinary conservation measures or trigger advanced stages of its WSCP due to supply shortages. However, the 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 29

City remains committed to ongoing water conservation and will continue to enforce standard water waste prohibitions to preserve regional storage.

Table 6-1. DWR 7-5 Five-Year Drought Risk Assessment (AF) Category 2026 2027 2028 2029 2030
Total Water Use (Demand) 21,087 19,607 20,986 21,834 20,795 Total Supplies 21,087 19,607 20,986 21,834 20,795
Surplus/Shortfall without WSCP Action 0 0 0 0 0
Planned WSCP Actions (use reduction and
supply augmentation)
WSCP – Supply Augmentation Benefit 0 0 0 0 0
WSCP – Use Reduction Savings Benefit 0 0 0 0 0
Revised Surplus/(Shortfall) 0 0 0 0 0
Resulting % Use Reduction from WSCP Action 0% 0% 0% 0% 0%

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 30

7. Water Shortage Contingency Plan
The Water Shortage Contingency Plan (WSCP) is a strategic plan developed by the City to proactively manage and respond to both anticipated and unforeseen water shortages. A water shortage is defined as a condition in which available water supplies are inadequate to meet expected customer demand at a specific point in time. Such shortages may result from various factors, including but not limited to, water supply quality changes, climate change, drought, regional power outage, and catastrophic events (e.g., earthquake). Additionally, the State may declare a statewide drought emergency and mandate that water suppliers reduce demand.

The City’s WSCP is a detailed approach which presents how the City intends to act, or respond, in the case of an actual water shortage. It outlines a process for conducting annual water supply and demand assessments and establishes clearly defined stages and response measures to respond to actual conditions. This level of preparedness enhances transparency, ensures accountability, and supports the City’s ability to maintain reliable water service during periods of supply disruption.

The WSCP was prepared in conjunction with the 2025 RUWMP and is presented as a standalone document that may be updated as necessary. No substantive changes have been incorporated into the 2025 WSCP compared to the 2020 version. Minor editorial updates were made for clarity and consistency; however, the content, procedures, and response actions remain relatively unchanged.

The City has consistently operated under a Level 2 watering schedule, as established by Ordinance 4122.

During the most recent drought, Pomona implemented its WSCP without requiring any adjustments.

Currently, the City is reviewing the requirements of Assembly Bill (AB) 1572. While the existing WSCP includes general conservation measures, it does not yet incorporate the specific definitions, exemptions, enforcement provisions, or timelines outlined in AB 1572. The City anticipates the need to amend Ordinance 4122 or adopt a new ordinance section to ensure full compliance with the legislation.

The City’s WSCP is included in Part 4, Appendix D-7.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 31

8. Demand Management Measures
The Demand Management Measures (DMMs) section provides a comprehensive description of the water conservation programs that the City has implemented for the past five years, is currently implementing, and plans to implement in order to reduce demand. The City met the 2020 Water Use Target through the implementation of these DMMs. They City expects to continue to implement current conservation programs to encourage conservation and achieve its water use targets.

8.1. Existing Demand Management Measures

8.1.1. Water Waste Prevention Ordinances
The City adopted Ordinance No. 4122 (“Water Conservation and Water Supply Shortage Program and Regulations”) in June 2009, which established regulations to prevent water waste. Ordinance No. 4122 includes the following restrictions:
⚫ Limitations on watering hours for lawn, landscape, or vegetated areas. ⚫ Limitations on watering duration to no more than 15 minutes per day per irrigation station. ⚫ Prohibitions on excessive water flow or runoff.
⚫ Prohibitions on washing down hard or paved surfaces (except for safety and sanitation with limitations).
⚫ Prohibitions on excessive pipeline leaks, breaks or malfunctions and obligation to repair them in a timely manner.
⚫ Prohibitions on operating a water fountain or other decorative water features that do not use re- circulated water.
⚫ Limitations of washing vehicles.
⚫ Prohibitions on serving drinking water at eating or drinking establishments (unless requested). ⚫ Commercial lodging establishments must provide the option to not launder daily. ⚫ Prohibitions on the installation of single pass cooling systems in buildings requesting new water service.
⚫ Prohibitions on the installation of non-recirculating water systems in new commercial car washes, new laundry systems, or other new water intensive operations. ⚫ Restaurants are required to use water conserving dish wash spray valves.

A copy of this Ordinance No. 4122 is provided in Part 4, Appendix D-4.

The City has continuously implemented its Water Waste Prevention Ordinance over the last five years. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 32

8.1.2. Metering
The City meters all customer connections, including separate metering for single-family residential, commercial, industrial, and landscape customers. Furthermore, if there is new development within the City, each facility is individually metered. Service charges for the City are based on the customers’ connection size. Further information regarding the City’s service fees and conservation pricing is provided in Section 8.1.3.

The City has continuously metered all connections over the last five years.

8.1.3. Conservation Pricing
The City’s current water rates structure is tiered based on the cost of service, which typically promotes water conservation. Domestic and irrigation customers are billed on separate inclining block rate structures, with a fixed service charge based on meter size. The rate structures include three tiers.

8.1.4. Public Education and Outreach
The City offers public information programs for customers to promote water conservation. The City provides marketing and outreach materials to its customers by using social media platforms, the City’s website, community outreach events, quarterly newsletters, school education programs, and direct communication to customers regarding their water use. Customers learn about rebates and additional programs through the City’s website (the website available at this link).

The City conducts water conservation school education programs to Pomona elementary schools.

Programs include school assemblies and lesson materials to educate students on the topics of water conservation. The City was no longer a member of the Water Education Water Awareness Committee (WEWAC) as of 2021. The City joined as a member in 2022 through TVMWD of the Public Water Agencies Group (PWAG) and active participation of the Communications and Education Team (CET) that promotes the education of water issues to local schools, including the Pomona Unified School District, essay contests to student and provides financial support for lesson plan materials to teachers, field trips about water, , and through the MWD program promotes the “Water is Life” art poster contest each year.

The City will continue the school education programs to promote water conservation.

The City provides public information programs to promote and educate customers on water conservation by hosting and participating in City and regional community events, providing bill inserts, and attending community meetings. Events include the Drinking Water Week, Imagine a Day Without Water, Storm Water Awareness Week, Wyland National Mayor’s Challenge for Water Conservation, Wyland Bus Mobile Learning experience, Fix a Leak Week, San Antonio Watershed Clean Up, National Night Out, Earth Day, the Chalk Art Festival, Concert in the Park, City Movie Night, and Public Works Day.

All outreach event flyers, rebate information, and general conservation program information are provided at City Hall, senior centers, social media, and on the City’s website. The City will continue these programs to promote water conservation.

Over the last five years, the City has continuously implemented public education and outreach activities. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 33

8.1.5. Programs to Assess and Manage Distribution System Real Losses The City's system is comprised mainly of single-family and multi-family dwellings. The City’s losses range approximately from 4 to 12%, as discussed in Section 2.1.3. The City has water conservation literature that alerts customers to be on the lookout for water system leaks and to correct them promptly. The City is available to assist customers in answering questions regarding leaks or higher than expected water usage. The City also offers a “Water Watcher Reporting Line” both online and via a phone number for residents to report visible leaks or excess runoff.

The City in 2021, began a new program to assist with outreach to residential customers called WaterView Software which aligns with SB606 and AB1668. The program is tailored for efficiency and allocation compliance, it tracks commercial, industrial, and institutional (CII) sectors water usage trends, manages high users, and identifies specific land classifications for rebating. The water conservation team utilizes the system to reach out to high users, and to monitor compliance.

The City prepares annual water loss audits (discussed in Section 2.1.3) to monitor water losses. City staff review the audits to track real and apparent losses. Losses are monitored by comparing water production to sales. The City regularly monitors its system and repairs leaks in a timely manner. To help in its effort to reduce and eliminate losses, the City has purchased various sound correlators for identifying system leaks. In areas where a leak is visible, staff is dispatched to pinpoint the leak, minimize the excavation area, and save resources. The City will continue these programs to assess and manage distribution system real losses.

Over the last five years, the City has continuously implemented the activities described here each year.

8.1.6. Water Conservation Program Coordination and Staffing Support The City’s Environmental Program Division of the Water Resources Department employs a full-time Environmental Compliance Supervisor, Water Conservation Specialist, and one part-time Technical Specialist for water conservation program coordination. Water conservation program staff are responsible for the following:
⚫ Compiling and submitting the SAFER reports, Water Loss Audit, and Annual Urban Water Use Objective and Water Use Report.
⚫ Answering the Water Watcher 24-Hour Reporting Line.
⚫ Sending letters to residents and businesses not complying with water conservation standards. ⚫ Creating outreach materials and the quarterly newsletter. ⚫ Staffing outreach table at City events.
⚫ Attending all CalWEP , MWD, TVMWD Coordinators, WaterSense, Water Use Efficiency, CET, and PWAG meetings
⚫ Distributing program and scholarship information to school district, teachers, and principals. ⚫ Organizing various conservation events.
2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 34

⚫ Creating social media posts.

The City will continue to provide water conservation program coordination and staffing support.

8.1.7. Other Demand Management Measures

8.1.7.1. MWD’s Residential Landscape Transformation Program In addition to the above DMMs, the City implements its own programs and collaborates with regional partners such as MWD. The City participates in MWD’s Residential Landscape Transformation Program to reward customers whose landscape designs utilize water-saving plants, technology, irrigation systems, and hardware. Incentives are presented on the City’s website (the website is available at this link).

Since 2022, the city has conducted 253 residential landscape transformations which include an evaluation, sprinkler tunes ups, weather-based irrigation controls for front and back yards. The program has been very successful.

The City has continuously implemented this program over the last five years.

8.1.7.2. Rebate Programs
Through TVMWD, the City participates in MWD’s regional rebate program, the SoCal WaterSmart Program, which is available to the City’s residential and commercial customers. There are residential rebates available for the purchase of high-efficiency clothes washing (HECW) machines, premium high- efficiency toilets (PHET), weather-based irrigation controllers (Smart Controllers), rain barrels, rain cisterns, and turf removal to promote water conservation. Some measures, including PHETs, Smart Controllers, and turf removal, are also available to commercial customers. The City’s commercial customers are additionally offered plumbing, landscaping, HVAC, and medical and dental equipment rebates. The City provides information about this program to customers on its website.

This program has been continuously in effect for the last five years.

8.1.7.3. U.S. Environmental Protection Agency’s (USEPA) WaterSense

2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 35

WaterSense, sponsored by the USEPA, is a great partnership program that simplifies water conservation.

It serves as both a label for water-efficient products and a valuable resource for water-saving tips. The WaterSense label provides consumers with an easy way to identify water-efficient products, new homes, and programs that meet the EPA's rigorous criteria for efficiency and performance. These labeled products use at least 20% less water while performing on par with or even better than standard models.

In addition, WaterSense collaborates with landscape irrigation professionals certified by labeled programs, emphasizing water efficiency.

Over the last five years, the City has provided information about this program to customers on its website.

8.1.7.4. Water Conservation Kits
The City’s Water Resources Department offers residents a free, personalized water conservation kit.

Customers can choose easy-to-install, water-saving devices, making a difference by saving water and lowering their monthly water bill in the process.

This program has been continuously in effect for the last five years. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 36

9. Adoption, Submittal, and Implementation
This section describes the City’s process for adopting, submitting, and implementing the 2025 RUWMP and WSCP .

9.1. Notice of Public Hearing
A joint notice was provided on behalf of all agencies whose 2025 UWMPs are part of the 2025 RUWMP to all cities and counties and other stakeholders within the region that that 2025 RUWMP is being prepared. This notice was sent at least 60 days prior to the City’s public hearing. The recipients are identified in Part 1 Chapter 1 of the 2025 RUWMP and include all cities and counties within the City’s service area. A second notice was provided to these cities and counties with the date and time of the public hearing and the location where the draft report was available for review.

The City provided notice to the public through its website and published announcements of the public hearing in a newspaper on two occasions before the hearing. Copies of the proof of publication are included in Part 4, Appendix D-2.

9.2. Public Hearing and Adoption
The City held a public hearing on May 18, 2026 to hear public comments and consider adopting this 2025 RUWMP and the City’s WSCP. As part of the public hearing, the City provided information on their baseline values, water use targets, and implementation plan required in the Water Conservation Act of 2009. The public hearing on the 2025 RUWMP took place before the adoption of the Plan, which allowed the City the opportunity to modify the 2025 RUWMP in response to any public input before adoption.

After the hearing, the Plan was adopted as prepared or as modified after the hearing.

The City’s adoption resolution for the 2025 RUWMP and the City’s WSCP is included in Part 4, Appendix D-3.

9.3. Plan Submittal
The City will submit the 2025 RUWMP and the City’s WSCP to DWR, the State Library, and cities and counties within 30 days after adoption. The 2025 RUWMP submittal to DWR will be done electronically through DWR’s “Water Use Efficiency (WUE) Data Portal” website. The complete set of DWR Submittal Tables for the City is included in Part 4, Appendix D-5.

9.4. Public Availability
Within 30 days of submitting its Plan to DWR, the City will make the 2025 RUWMP and the City’s WSCP available for public review. Copies will be accessible during normal business hours at the City Clerk’s Office in City Hall and posted on the City’s website for public viewing. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 37

9.5. Amending an Adopted UWMP or WSCP
If the adopted 2025 RUWMP or the City’s WSCP is amended, each of the steps for notification, public hearing, adoption, and submittal will also be followed for the amended plan. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 38

10. References
American Water Works Association (AWWA). (2020-2024). Validated Water Loss Audit Reports for the City of Pomona, Calendar Years (CY) 2020 through 2024.

The AWWA Audit Reports are available at this link.

California Department of Water Resources (DWR). (2021, March). Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use. Sacramento, CA.

California Department of Water Resources (DWR). (2026, February). Urban Water Management Plan Guidebook. State of California Natural Resources Agency California State Water Resources Control Board (SWRCB). (2024). Making Conservation a California Way of Life (CWOL) Regulation. The SWRCB CWOL regulation is available at this link.

Chino Basin Watermaster. (2024). 47th Annual Report, Fiscal Year 2023–2024.

The Chino Basin 2023-2024 Annual Report is available at this link.

Chino Basin Watermaster. Approved 2024/2025 Assessment Package (Production Year 2023/2024).

November 21, 2024. The 2024/2025 Assessment Package is available at this link.

City of Pomona. (2009). Recycled Water Master Plan.

The Recycled Water Master Plan is available at this link.

City of Pomona. (2020). 2020 Urban Water Management Plan. City of Pomona.

City of Pomona. Agency Website. The City of Pomona website is available at this link.

City of Pomona. (2025-2026). City of Pomona Provided Data. Data and information provided by City of Pomona to GEI Consultants.

Metropolitan Water District of Southern California (MWD) (2025). 2025 Urban Water Management Plan Supply Reliability Analysis and Drought Risk Assessment.

Metropolitan Water District of Southern California (MWD). (2026, February). 2025 Urban Water Management Plan. The MWD 2025 UWMP is available at this link.

Six Basins Watermaster. (2025, March). Annual Report – Calendar Year 2024. Final Report.

The Six Basins 2024 Annual Report is available at this link.

Southern California Association of Governments (SCAG). Regional Data and Forecasts. SCAG, March 2021.

Southern California Association of Governments (SCAG) (2021, March). Regional Housing Needs Assessment (RHNA) Allocation Plan, Sixth Cycle (October 2021-October 2029). SCAG. 2025 Urban Water Management Plan: Individual Chapter
City of Pomona
April 2026

GEI Consultants, Inc. 39

Southern California Association of Governments (SCAG). (2024). Demographics and Regional Forecasting Data. SCAG.

Three Valleys Municipal Water District (TVMWD). (2025, February). Water Resources Master Plan.

The TVWMD 2025 Water Resources Master Plan is available at this link.

U.S. Census Bureau. (2024). 2020 Census Data. United States Census Bureau.

United States Environmental Protection Agency (USEPA). (2026). WaterSense Program.

The USEPA WaterSense Program is available at this link.

THREE VALLEYS REGIONAL URBAN

WATER MANAGEMENT PLAN
Regional Supporting Information

PUBLIC REVIEW DRAFT
2025 Part 3:

APRIL 2026

THREE VALLEYS REGIONAL

URBAN WATER MANAGEMENT PLAN
Regional Supporting Information2025 Part 3:

APRIL 2026
Prepared by GEI Consultants, Inc. and Water Systems Consulting, Inc.

2025 RUWMP – Part 3 Appendices
A: RUWMP Checklist
Requirement Summary 2025 Regional UWMP Location Compliance Status
Coordination with local agencies and
shared supplies
Part 1 Chapter 1
Section 3 Met
Public participation prior to adoption
Part 1 Chapter 1
Section 1.3.2
Part 3 Appendix B-C
Met
Public hearing and adoption Part 1 Chapter 1
Section 1.4 Met
Submittal to DWR and State Library Part 3 Appendix G Met Describe service area and regional
setting
Part 1 Chapter 1
Section 1 Met
Climate description
Part 1 Chapter 2
Section 1
Part 3 Appendix I
Met
Demographics & population
projections
Part 1 Chapter 2
Sections 3 Met
Land use Part 1 Chapter 2
Section 4 Met
Identify and quantify existing and
planned water supplies Part 1 Chapters 3 and 5 Met
Normal, single-dry, and five-year
drought supply Part 1 Chapter 5 Met
Management of multiple sources Part 1 Chapter 3 Met
Planned water supply projects Part 1 Chapter 3
Section 9 Met
Transfers/exchanges Part 1 Chapter 3
Section 6 Met
Desalination opportunities Part 1 Chapter 3
Section 8
Basin descriptions Part 1 Chapter 3
Section 2 Met
Adjudication / SGMA status Part 1 Chapter 3
Part 3 Appendix K-P Met
Historic and projected pumping Part 1 Chapter 3 Met
Wastewater treatment and recycled
water use
Part 1 Chapter 3
Section 5 Met
Planned reuse and feasibility Part 1 Chapter 3
Section 5.3 Met
Historic and projected water use Part 1 Chapter 4 Met
SBX7-7 compliance Part 1 Chapter 4
Section 2.1 Met
UWUO & CWOL framework Part 1 Chapter 4
Section 2.2 Met
Requirement Summary 2025 Regional UWMP Location Compliance Status
Demand Management Measures
(DMMs)
Part 1 Chapter 4
Section 2.3 Met
20-year WSRA Part 1 Chapter 5 Met
Lay description of WSRA Part 1 Chapter 1
Executive Summary Met
Five-year drought risk analysis Part 1 Chapter 5
Section 2.3 Met
Lay description of DRA
Part 1 Chapter 1
Executive Summary
Part 1 Chapter 5
Met
WSCP summary and consistency Part 1 Chapter 1 Met

2025 RUWMP – Part 3 Appendices

B: 60-Day Notice of Preparation Letters
Agency 60-Day Notice of Preparation Reference
Three Valleys Municipal Water District Part 4 Appendix A-2 – Attachment 1 City of Glendora Part 4 Appendix B-2 – Attachment 1
City of La Verne Part 4 Appendix C-2 – Attachment 1
City of Pomona Part 4 Appendix D-2 – Attachment 1
Golden State Water Company - Claremont Part 4 Appendix E-2 – Attachment 1 Golden State Water Company - San Dimas Part 4 Appendix F-2 – Attachment 1 Rowland Water District Part 4 Appendix G-2 – Attachment 1 Walnut Valley Water District Part 4 Appendix H-2 – Attachment 1

2025 RUWMP – Part 3 Appendices

C: Notice Distribution Lists
To be included in final document.
2025 RUWMP – Part 3 Appendices

D: Proofs of Publication
To be included in final document.
2025 RUWMP – Part 3 Appendices

E: Regional Workshops Materials
2025 RUWMP – Part 3 Appendices

E – Attachment 1: Regional Workshop #1 Materials
To view the materials for regional workshop #1, use this link. 2025 RUWMP – Part 3 Appendices

E – Attachment 2: Regional Workshop #2 Materials
To view the materials for regional workshop #2, use this link. 2025 RUWMP – Part 3 Appendices

F: Three Valleys Regional Urban Water Management Plan
Adoption Resolution
To be included in final document.
2025 RUWMP – Part 3 Appendices

G: Transmittal Letters to State Library and Cities/Counties To be included in final document.
2025 RUWMP – Part 3 Appendices

H: Three Valleys Municipal Water District 2025 Water
Resources Master Plan
To view the 2025 Water Resources Master Plan, use this link. 2025 RUWMP – Part 3 Appendices

I: 2024 Climate Change Vulnerability Analysis
To be included in final document.
2025 RUWMP – Part 3 Appendices

J: Metropolitan Water District Wholesaler Reliability Data To be included in final document.
2025 RUWMP – Part 3 Appendices

K: Main Basin Materials
2025 RUWMP – Part 3 Appendices

K – Attachment 1: Main San Gabriel Basin Judgment
To view the Main San Gabriel Basin Judgement, use this link. 2025 RUWMP – Part 3 Appendices

K – Attachment 2: Main San Gabriel Basin Five-Year Water Quality and Supply Plan (2023-2028)
To view the Five-Year Water Quality and Supply Plan for 2023-2028, use this link. 2025 RUWMP – Part 3 Appendices

K – Attachment 3: Three Valleys Municipal Water
District/Metropolitan Water District Main San Gabriel Basin Cyclic Storage Agreement
To be included in final document.
2025 RUWMP – Part 3 Appendices

K – Attachment 4: Puente Basin Water Agency Storage and Export Agreement
To be included in final document.
2025 RUWMP – Part 3 Appendices

L: Chino Basin Materials
2025 RUWMP – Part 3 Appendices

L – Attachment 1: Chino Basin Judgment (1978)
To view the 1978 Chino Basin Judgment, use this link.
2025 RUWMP – Part 3 Appendices

L – Attachment 2: Chino Basin Peace Agreement (2000)
To view the 2000 Chino Basin Peace Agreement, use this link. 2025 RUWMP – Part 3 Appendices

L – Attachment 3: Three Valleys Municipal Water District One-Time Storage Agreement (Chino Basin)
To be included in final document.
2025 RUWMP – Part 3 Appendices

L – Attachment 4: Chino Basin Optimum Basin
Management Program
To view the Optimum Basin Management Program, use this link. 2025 RUWMP – Part 3 Appendices

M: Six Basins Materials
2025 RUWMP – Part 3 Appendices

M – Attachment 1: Six Basins Judgment (1998)
To view the 1998 Six Basins Judgement, use this link.
2025 RUWMP – Part 3 Appendices

M – Attachment 2: Three Valleys Municipal Water District Operational Storage Account Agreement (Six Basins)
To be included in final document.
2025 RUWMP – Part 3 Appendices

M – Attachment 3: Six Basins Strategic Plan
To view the Six Basins Strategic Plan, use this link.
2025 RUWMP – Part 3 Appendices

N: Spadra Basin Materials
2025 RUWMP – Part 3 Appendices

N – Attachment 1: Spadra Basin Groundwater Sustainability Agency Memorandum of Agreement
To view the GSA Memorandum of Agreement, use this link
2025 RUWMP – Part 3 Appendices

N – Attachment 1: Spadra Basin Groundwater Sustainability Plan
To view the Groundwater Sustainability Plan, use this link. 2025 RUWMP – Part 3 Appendices

O: Covina Valley Water Company Pre-1914 Appropriative
Water Rights Documentation
To view the Pre-1914 Appropriative Water Rights Documentation, use this link. 2025 RUWMP – Part 3 Appendices

P: City of Pomona Pre-1914 Appropriative Water Rights
Documentation
To view the Pre-1914 Appropriative Water Rights Documentation, use this link. 2025 RUWMP – Part 3 Appendices

Q: SWRCB Wastewater Change Petition Order WW0104
To view Wastewater Change Petition Order WW0104, use this link. 2025 RUWMP – Part 3 Appendices

R: SWRCB Wastewater Change Petition Order WW0107
To view Wastewater Change Petition Order WW0107, use this link. 2025 RUWMP – Part 3 Appendices

S: Metropolitan Water District Chino Basin Dry-Year Yield Program Agreement
To view Dry-Year Yield Program Agreement, use this link. 2025 RUWMP – Part 3 Appendices

T: Central Basin Adjudication
To view Central Basin Adjudication, use this link.
2025 RUWMP – Part 3 Appendices

U: Puente Basin Materials
2025 RUWMP – Part 3 Appendices

U – Attachment 1: Puente Basin Judgment (1985)
To view 1985 Puente Basin Judgment, use this link.
2025 RUWMP – Part 3 Appendices

U – Attachment 2: Puente Narrows Agreement
To view Puente Narrows Agreement, use this link.

THREE VALLEYS REGIONAL URBAN

WATER MANAGEMENT PLAN
Urban Water Management Plan
Agency Supporting Information

PUBLIC REVIEW DRAFT
2025 Part 4:

APRIL 2026

THREE VALLEYS REGIONAL

URBAN WATER MANAGEMENT PLAN
Urban Water Management Plan
Agency Supporting Information
2025 Part 4:

APRIL 2026
Prepared by GEI Consultants, Inc. and Water Systems Consulting, Inc.

City of Pomona
Appendix D
2025 RUWMP Part 4
D
2025 Part 4: City of Pomona Appendix D

D1: UWMP Compliance Checklist
Retail
(x = required) Order 2025 Guidebook
Location
Water Code
Section Summary as Applies to UWMP Subject Relevant Submittal Table 2025 UWMP Location
x 1 Chapter 1 10615 A plan shall describe and evaluate sources of supply, reasonable and practical efficient uses, reclamation and demand management activities.

Introduction and
overview n/a Part 2 Chapter 4
Part 1 Chapter 3
x 1 Chapter 1 10630.5
Each plan shall include a simple description of the Supplier’s plan including water availability, future requirements, a strategy for meeting needs, and other pertinent information. Additionally, a Supplier may also choose to include a simple description at the beginning of each chapter.

Plan preparation n/a Part 2 Chapter 4
Executive Summary
x 2.1 Section 2.1 10620(b) Every person that becomes a Supplier shall adopt UWMP within one year after it has become a Supplier. Plan preparation n/a Part 2 Chapter 4 x 2.5 Section 2.5 10644 Supplier shall report the Public Water Systems number, volume of delivered water, and number of connections that are included in this UWMP. Plan preparation 2-1 Part 2 Chapter 4 Section

2.1 x 2.5 Section 2.5 10644 Supplier shall report if this UWMP is an individual UWMP and whether the Supplier belongs to a regional UWMP or regional alliance. Plan preparation 2-2 Part 2 Chapter 4 x 2.5 Section 2.5 10644 Supplier shall report whether the data is in fiscal or calendar years and the units of measure used for reporting water volumes. Plan preparation 2-3 Part 2 Chapter 4 x 2.4 Section 2.4 10642
Provide supporting documentation that the Supplier has encouraged active involvement of diverse social, cultural, and economic elements of the population within the service area prior to and during the preparation of the plan and contingency plan.

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

Plan preparation n/a Part 4 Appendix D-2
x 2.4 Section 2.4.1 10631(h) Retail Suppliers will include documentation that they have provided their Wholesale Supplier(s)—if any—with water use projections from that source. Plan preparation 2-4 R Part 1 Chapter 5 n/a 2.4 Section 2.4.1 10631(h)
Wholesale Suppliers will provide their Suppliers with identification and quantification of the existing and planned sources of water available from the Wholesale Supplier to the Supplier during various water year types.

Plan preparation 2-4 W n/a
x 3 Chapter 3.0 10631(a) Describe the Supplier service area. System description n/a Part 2 Chapter 4 Section

1.1 x 3.3 Section 3.3 10631(a) Describe the climate of the Supplier’s service area. System description n/a Part 2 Chapter 4 Section

1.1 x 3.4 Section 3.4.1 10631(a) Provide the current and projected service area populations for 2030, 2035, 2040, 2045 and optionally 2050. System description 3-1 Part 2 Chapter 4 Section

1.1 x 3.4 Section 3.4.2 10631(a) Describe other social, economic, and demographic factors affecting the Supplier’s water management planning. System description n/a Part 2 Chapter 4 Section

1.1 x 3.5 Section 3.5 10631(a)
Describe the land uses within the service area… include the current and projected land uses within the existing or anticipated service area affecting the Supplier’s water management planning. Describe the land uses within the service area.

System description and
baselines n/a Part 2 Chapter 4 Section

1.1 x 4.2 Sections 4.2.3 and 4.2.4 10631(d)(1) Quantify past, current, and projected water use, identifying the uses among water use sectors. System water use 4-1 and 4-2 Part 2 Chapter 4 Section 2 x 4.3 Section 4.3.1 10631(d)(3)(A) Report the distribution system water loss for each of the five years preceding the plan update. System water use 4-5 Part 2 Chapter 4 Section

2.1.3 x 4.3 Section 4.3.2 10631(d)(3)(C) Retail Suppliers shall provide data to show the distribution loss standards were met. System water use 4-6 Part 2 Chapter 4 Section

2.1.3 x 4.2 Section 4.2.5.4 10631.1(a) Include projected water use needed for lower income housing projected in the service area of the Supplier. System water use 4-3 Part 2 Chapter 4 Section

2.3 x 4.2 Section 4.2.5.3 10631(d)(4)(A) In projected water use, include estimates of water savings from adopted codes, plans, and other policies or laws. System water use 4-3 Part 2 Chapter 4 Section

2.2 x 4.2 Section 4.2.5.3 10631(d)(4)(B) Provide citations of codes, standards, ordinances, or plans used to make water use projections. System water use 4-3 Part 2 Chapter 4 Section

2.2 x 4.2 Section 4.2.5.3 10631(d)(4)(B)(ii)
To the extent that a Supplier reports the information described in subparagraph (A), an urban water Supplier shall… Indicate the extent that the water use projections consider savings from codes, standards, ordinances, or transportation and land use plans. Water use projections that do not account for these water savings shall be noted of that fact.

System water use 4-3 Part 2 Chapter 4 Section
2 x 4.2 Section 4.2.5.6 10635(b) Demands under climate change considerations must be included as part of the drought risk assessment. System water use n/a
Part 2 Chapter 4 Section

2.4 Part 1 Chapter 5
n/a 5.1 Section 5.1 10608.36
Wholesale Suppliers shall include an assessment of present and proposed future measures, programs, and policies to help their Retail Suppliers achieve targeted water use reductions.

Baselines and targets n/a n/a
x 5.2 Section 5.2 10608.4
Retail Suppliers shall report on their compliance in meeting their water use targets. Reporting requirements will vary depending on whether the Supplier:
- Was considered an urban retail water supplier in 2020, - Met its 2020 target in 2020, or
- Was part of a merger or consolidation since 2020.

Chapter 5 Subsections 5.2.1, 5.2.2, and 5.2.3 address each of these situations.

Baselines and targets 5-1 Part 2 Chapter 4 Section
3 x 6.1 Section 6.1 10631(b)(2) When multiple sources of water supply are identified, describe the management of each supply in relationship to other identified supplies. System supplies n/a Part 2 Chapter 4 Section
4 Part 1 Chapter 3
x 6.1 Sections 6.1 and 6.2 10631(b)(1)
Provide a discussion of anticipated supply availability under a normal, single dry year, and a drought lasting five years, as well as more frequent and severe periods of drought, including changes in supply due to climate change.

System supplies n/a
Part 2 Chapter 4 Section
4 Part 2 Chapter 4 Section

5.3 Part 1 Chapter 5 Section
2 x 6.2 Section 6.2.2 10631(b)(4)(C)
Indicate whether groundwater is an existing or planned source of water available to the Supplier. If groundwater is identified as an existing or planned source of water… (include) a detailed description and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past five years.

Water supplies and
recycled water 6-1 Part 2 Chapter 4 Section

4.2 x 6.2 Section 6.2.2 10631(b)(4)(A)
Indicate whether a groundwater sustainability plan or groundwater management plan has been adopted by the Supplier or if there is any other specific authorization for groundwater management. Include a copy of the plan or authorization.

System supplies n/a
Part 2 Chapter 4 Section

4.2 Part 1 Chapter 3
x 6.2 Section 6.2.2 10631(b)(4)(B) Describe the groundwater basin. System supplies n/a Part 2 Chapter 4 Section

4.2 Part 1 Chapter 3
x 6.2 Section 6.2.2 10631(b)(4)(B)
Indicate if the basin has been adjudicated and include a copy of the court order or decree and a description of the amount of water the Supplier has the legal right to pump.

System supplies n/a
Part 2 Chapter 4 Section

4.2 Part 1 Chapter 3
x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… (include) information as to whether DWR has identified the basin as a high- or medium-priority basin in the most current official departmental bulletin…
Water supplies and
recycled water n/a
Part 2 Chapter 4 Section

4.2 Part 1 Chapter 3
x 6.2 Section 6.2.2 10631(b)(4)(B)
For unadjudicated basins… describe efforts by the Supplier to coordinate with sustainability or groundwater agencies to achieve sustainable groundwater conditions.

Water supplies and
recycled water n/a
Part 2 Chapter 4 Section

4.2 Part 1 Chapter 3
x 6.2 Section 6.2.2. 10631(b)(4)(C)
If groundwater is identified as an existing or planned source of water… (include) a detailed description and analysis of the location, amount and sufficiency of groundwater pumped by the Supplier for the past five years.

System supplies n/a Part 2 Chapter 4 Section

4.2 x 6.2 Section 6.2.2 10631(b)(4)(D) Provide a detailed description and analysis of the amount and location of groundwater that is projected to be pumped. System supplies 6-9 Part 2 Chapter 4 Section

4.8 x 6.1 Section 6.1 10631(b) Identify and quantify the existing and planned sources of water available for 2025, 2030, 2035, 2040, 2045 and optionally 2050. System supplies 6-8 and 6-9 Part 2 Chapter 4 Section

4.8 Part 1 Chapter 3
Part 1 Chapter 5
x 6.2 Section 6.2.7 10631(c) Describe the opportunities for exchanges or transfers of water on a short- term or long-term basis. System supplies n/a Part 2 Chapter 4 Section

4.6 x 6.2 Section 6.2.5 10633(a)
Describe the wastewater collection and treatment systems in the Supplier’s service area with quantified amount of collection and treatment and the disposal methods.

System supplies
(recycled water) 6-2 Part 2 Chapter 4
Section 4.5
x 6.2 Section 6.2.5 10633(b)
Describe the quantity of treated wastewater that meets recycled water standards, is being discharged, and is otherwise available for use in a recycled water project.

System supplies
(recycled water) 6-3 Part 2 Chapter 4 Section

4.5 x 6.2 Section 6.2.5 10633(c) Describe the recycled water currently being used in the Supplier's service area.

System supplies
(recycled water) 6-4 Part 2 Chapter 4 Section

4.5.1 x 6.2 Section 6.2.5 10633(d) Describe and quantify the potential uses of recycled water and provide a determination of the technical and economic feasibility of those uses.

System supplies
(recycled water) 6-4
Part 2 Chapter 4 Section

4.5 Part 1 Chapter 3 Section
5 x 6.2 Section 6.2.5 10633(e)
Describe the projected use of recycled water within the Supplier's service area at the end of 5, 10, 15, and 20 years, and describe the actual use of recycled water in comparison to uses previously projected.

System supplies
(recycled water) 6-4 and 6-5
Part 2 Chapter 4 Section

4.5 Part 1 Chapter 3 Section
5 x 6.2 Section 6.2.5 10633(f)
Describe the actions that may be taken to encourage the use of recycled water and the projected results of these actions in terms of acre-feet of recycled water used per year.

System supplies
(recycled water) 6-6 Part 1 Chapter 3 Section
5 x 6.2 Section 6.2.5 10633(g) Provide a plan for optimizing the use of recycled water in the Supplier's service area.

System supplies
(recycled water) n/a Part 1 Chapter Section 5
x 6.2 Section 6.2.6 10631(g) Describe desalinated water project opportunities for long-term supply. System supplies 6-7 Part 1 Chapter 3 Section 8 x 6.2 Section 6.2.10 10631(f)
Describe the expected future water supply projects and programs that may be undertaken by the water Supplier to address water supply reliability in average, single-dry, and for a period of drought lasting five consecutive water years.

System supplies 6-7
Part 2 Chapter 1 Section

4.7 Part 1 Chapter 3 Section
9 x 6.3 Section 6.3 and
Appendix O 10631.2(a) The UWMP must include energy information, as stated in the code, that a Supplier can readily obtain.

System suppliers,
energy intensity
O-1A, O-1B, O-1C,
and O-2
Part 2 Chapter 4 Section

4.9 Part 4 Appendix D
x 7.1 Section 7.1 10634
Provide information on the quality of existing sources of water available to the Supplier and the manner in which water quality affects water management strategies and supply reliability.

Water supply reliability
assessment n/a
Part 2 Chapter 4 Section
5 Part 1 Chapter 3
x 7.2 Section 7.2 10635(a)
Service Reliability Assessment: Assess the water supply reliability during normal, dry, and a drought lasting five consecutive water years by comparing the total water supply sources available to the Supplier with the total projected water use over the next 20 years.

Water supply reliability
assessment 7-2, 7-3, and 7-4
Part 2 Chapter 4
Section 5.3
Part 1 Chapter 5 Section
2 x 7.2 Section 7.2.3 10620(f) Describe water management tools and options to maximize resources and minimize the need to import water from other regions.

Water supply reliability
assessment n/a Part 1 Chapter 3
x 7.3 Section 7.3 10635(b) Provide a drought risk assessment as part of information considered in developing the demand management measures and water supply projects.

Water supply reliability
assessment n/a
Part 2 Chapter 4 Section

2.4 Part 1 Chapter 5
x 7.3 Section 7.3 10635(b)(1)
Include a description of the data, methodology, and basis for one or more supply shortage conditions that are necessary to conduct a drought risk assessment for a drought period that lasts five consecutive years.

Water supply reliability
assessment n/a
Part 2 Chapter 4 Section
6 Part 1 Chapter 5
x 7.3 Section 7.3 10635(b)(2) Include a determination of the reliability of each source of supply under a variety of water shortage conditions.

Water supply reliability
assessment n/a
Part 2 Chapter 8 Section
6 Part 1 Chapter 5
x 7.3 Section 7.3 10635(b)(3) Include a comparison of the total water supply sources available to the Supplier with the total projected water use for the drought period.

Water supply reliability
assessment 7-5
Part 2 Chapter 4 Section
6 Part 1 Chapter 5
x 7.3 Section 7.3 10635(b)(4)
Include considerations of the historical drought hydrology, plausible changes on projected supplies and demands under climate change conditions, anticipated regulatory changes, and other locally applicable criteria.

Water supply reliability
assessment n/a
Part 2 Chapter 4 Section

5.1 Part 1 Chapter 5
x 8 Chapter 8 10632(a) Provide a water shortage contingency plan (WSCP) with specified elements below.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8 Chapter 8 10632(a)(1) Provide an analysis of water supply reliability (from Guidebook Chapter 7) in the WSCP.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.2 Section 8.2 10632(a)(2)(A) Provide the written decision-making process and other methods that the Supplier will use each year to determine its water reliability.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.2 Section 8.2 10632(a)(2)(B) Provide data and methodology to evaluate the Supplier’s water reliability for the current year and one dry year pursuant to factors in the code.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.3 Section 8.3 10632(a)(3)(A)
Define six standard water shortage levels of 10%, 20%, 30%, 40%, 50% shortage, and greater than 50% shortage. These levels shall be based on supply conditions, including percent reductions in supply, changes in groundwater levels, changes in surface elevation, or other conditions. The shortage levels shall also apply to a catastrophic interruption of supply.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.3 Section 8.3 10632(a)(3)(B) Suppliers with an existing WSCP that uses different water shortage levels must cross reference their categories with the six standard categories.

Water shortage
contingency planning 8-1 Part 4 Appendix D-7
x 8.4 Section 8.4 10632(a)(4)(A) Suppliers with WSCPs that align with the defined shortage levels must specify locally appropriate supply augmentation actions.

Water shortage
contingency planning 8-2 Part 4 Appendix D-7
x 8.4 Section 8.4 10632(a)(4)(B) Specify locally appropriate demand reduction actions to adequately respond to shortages.

Water shortage
contingency planning 8-3 Part 4 Appendix D-7
x 8.4 Section 8.4 10632(a)(4)(C) Specify locally appropriate operational changes. Water shortage contingency planning 8-2 Part 4 Appendix D-7
x 8.4 Section 8.4 10632(a)(4)(D)
Specify additional mandatory prohibitions against specific water use practices that are in addition to State-mandated prohibitions are appropriate to local conditions.

Water shortage
contingency planning Table 8-3 Part 4 Appendix D-7
x 8.4 Section 8.4 10632(a)(4)(E) Estimate the extent to which the gap between supplies and demand will be reduced by implementation of the action.

Water shortage
contingency planning 8-2 and 8-3 Part 4 Appendix D-7
x 8.4 Section 8.4.6 10632.5 The UWMP shall include a seismic risk assessment and mitigation plan. Water shortage contingency plan n/a Part 4 Appendix D-7
x 8.5 Section 8.5 10632(a)(5)(A) Suppliers must describe that they will inform customers, the public and others regarding any current or predicted water shortages.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.5 Section 8.5 10632(a)(5)(B),
10632(a)(5)(C)
Suppliers must describe that they will inform customers, the public and others regarding any shortage response actions triggered or anticipated to be triggered and other relevant communications.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.6 Section 8.6 10632(a)(6) Retail Supplier must describe how it will ensure compliance with and enforce provisions of the WSCP.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.7 Section 8.7 10632(a)(7)(A) Describe the legal authority that empowers the Supplier to enforce shortage response actions.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.7 Section 8.7 10632(a)(7)(B) Provide a statement that the Supplier will declare a water shortage emergency per Water Code Chapter 3. Water Shortage Emergencies.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.7 Section 8.7 10632(a)(7)(C)
Provide a statement that the Supplier will coordinate with any city or county within which it provides water for the possible proclamation of a local emergency.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.8 Section 8.8 10632(a)(8)(A) Describe the potential revenue reductions and expense increases associated with activated shortage response actions.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.8 Section 8.8 10632(a)(8)(B)
Provide a description of mitigation actions needed to address revenue reductions and expense increases associated with activated shortage response actions.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.8 Section 8.8 10632(a)(8)(C) Retail Suppliers must describe the cost of compliance with Water Code Chapter 3.3, Excessive Residential Water Use During Drought.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.9 Section 8.9 10632(a)(9)
Retail Suppliers must describe the monitoring and reporting requirements and procedures that ensure appropriate data are collected, tracked, and analyzed for purposes of monitoring customer compliance.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.10 Section 8.10 10632(a)(10)
Describe reevaluation and improvement procedures for monitoring and evaluation the WSCP to ensure risk tolerance is adequate and appropriate water shortage mitigation strategies are implemented.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.11 Section 8.11 10632(b)
Analyze and define water features that are artificially supplied with water, including ponds, lakes, waterfalls, and fountains, separately from swimming pools and spas.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 8.12 Section 8.12 10632(c) Make available the WSCP to customers and any city or county where it provides water within 30 days after adoption of the plan.

Water shortage
contingency planning n/a Part 4 Appendix D-7
x 9.1 Sections 9.1 10631(e)(1)
Retail Suppliers shall provide a description of the nature and extent of each demand management measure implemented over the past five years. The description will address specific measures listed in code.

Demand management
measures n/a Part 2 Chapter 4 Section
8 n/a 9.2 Sections 9.2 10631(e)(2)
Wholesale Suppliers shall describe specific demand management measures listed in code, their distribution system asset management program, and Supplier assistance program.

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

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.2 Section 10.2.1 10621(b)
Notify, at least 60 days prior to the public hearing, any city or county within which the Supplier provides water that the Supplier will be reviewing the UWMP and considering amendments or changes to the plan.

Plan adoption,
submittal, and
implementation
10-1
Part 2 Chapter 4 Section
9 Part 4 Appendix D-2
x 10.4 Section 10.4 10621(f) Each urban water Supplier shall update and submit its 2025 plan to DWR by July 1, 202 6.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.2 Sections 10.2.2, 10.3,
and 10.5 10642
Provide supporting documentation that the Supplier made the UWMP and WSCP available for public inspection, published notice of the public hearing, and held a public hearing about the UWMP and WSCP.

Plan adoption,
submittal, and
implementation
n/a Part 4 Appendix D-3
x 10.2 Section 10.2.2 10642 The Supplier is to provide the time and place of the hearing to any city or county within which the Supplier provides water.

Plan adoption,
submittal, and
implementation
10-1 Part 4 Appendix D-3
x 10.3 Section 10.3.2 10642 Provide supporting documentation that the UWMP and WSCP has been adopted as prepared or modified.

Plan adoption,
submittal, and
implementation
n/a Part 4 Appendix D-3
x 10.4 Section 10.4 10644(a) Provide supporting documentation that the Supplier has submitted their UWMP to the California State Library.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.4 Section 10.4 10644(a)(1)
Provide supporting documentation that the Supplier has submitted their UWMP to any city or county within which the Supplier provides water no later than 30 days after adoption.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.4 Sections 10.4.1 and

10.4.2 10644(a)(2) The UWMP, or amendments to the UWMP, submitted to DWR shall be submitted electronically.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.7 Section 10.7.2 10644(b) If revised, submit a copy of the WSCP to DWR within 30 days of adoption.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.5 Section 10.5 10645(a)
Provide supporting documentation that, not later than 30 days after filing a copy of its UWMP with DWR, the Supplier has or will make the plan available for public review during normal business hours.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.5 Section 10.5 10645(b)
Provide supporting documentation that, not later than 30 days after filing a copy of its WSCP with DWR, the Supplier has or will make the plan available for public review during normal business hours.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 x 10.6 Section 10.6 10621(c) If Supplier is regulated by the Public Utilities Commission, include its plan and contingency plan as part of its general rate case filings.

Plan adoption,
submittal, and
implementation
n/a Part 2 Chapter 4 Section
9 2025 Part 4: City of Pomona Appendix D

D2: Public Outreach
2025 Part 4: City of Pomona Appendix D

D2: Attachment 1 – 60 Day Notices
The 60-Day Notices are available upon request from the Agency at this link. 2025 Part 4: City of Pomona Appendix D

D2: Attachment 2 – Regional Workshop #1 Materials
To be included in the final document.
2025 Part 4: City of Pomona Appendix D

D2: Attachment 3 – Regional Workshop #2 Materials
To be included in the final document.
2025 Part 4: City of Pomona Appendix D

D3: Adoption Resolution
To be included in the final document.
2025 Part 4: City of Pomona Appendix D

D4: Ordinances
The following ordinance is available online. Select the link below to view Ordinance No. 4122.
2025 Part 4: City of Pomona Appendix D

D5: DWR Tables
Submittal Table 2-1 Retail: Public Water Systems

Public Water System
Number
Public Water System
Name
Number of Municipal
Connections 2025
Volume of Water
Supplied 2025 (AF)
CA1910126 City of Pomona 31,056 18,298
Total 31,056 18,298
Submittal Table 2-2: Plan Identification
Type of Plan Name of Regional Alliance or RUWMP
Individual UWMP Three Valleys Regional Urban Water
Management Plan

Submittal Table 2-3: Supplier Identification
Type of Supplier Year Type
Month and date
that the year begins
(mm/dd)
Units of measure
used in UWMP
Supplier is a retail supplier Calendar Year 01/01 AF

Submittal Table 2-4 Retail: Water Supplier Information Exchange The retail Supplier has informed the following wholesale supplier(s) of projected water use.

Wholesale Water Supplier Name
Three Valleys Municipal Water District

Submittal Table 3-1 Retail: Population - Current and Projected Category 2025 2030 2035 2040 2045 2050(opt)
Population Served 155,836 158,803 161,770 163,270 164,770 166,270

Submittal Table 4-1 Retail: Total Uses for Potable and Non-Potable Water — Actual Use Type
Additional
Description
(as needed)
2025 Actual Water
Use
Potable or Non-
Potable
2025 Actual Water
Use
Volume (AF)
Single Family Potable 8,160
Multi-Family Potable 3,557
Commercial Potable 3,223
Institutional Potable 1,187
Landscape Potable 1,392
Distribution System Water
Loss Potable 779
Subtotal Potable 18,298
Subtotal Non-Potable 0
Total 18,298
Submittal Table 4-2 Retail: Total Uses for Potable, and Non-Potable Water — Projected Use Type Additional
Description
Projected Water
Use
Potable or Non-
Potable
(Optional)
Projected
Water Use
2030 (AF)
Projected
Water Use
2035 (AF)
Projected
Water Use
2040 (AF)
Projected
Water Use
2045 (AF)
Projected
Water Use
2050 opt (AF)
Single Family Potable 8,178 8,164 8,075 7,986 7,897
Multi-Family Potable 3,529 3,523 3,484 3,446 3,408
Commercial Potable 3,062 3,057 3,024 2,991 2,957
Institutional Potable 1,100 1,098 1,086 1,074 1,063
Landscape Potable 1,248 1,245 1,232 1,218 1,205
Distribution
System Water
Losses
Potable 1,157 1,155 1,143 1,130 1,117
Subtotal Potable 18,273 18,242 18,043 17,845 17,647
Subtotal Non-
Potable 0 0 0 0 0
Total 18,273 18,242 18,043 17,845 17,647
Submittal Table 4-3 Retail: Inclusion in Water Use Projections Projection Item Included in
Projections?
Are Future Water Savings Included in Projections? Yes
Are Lower Income Residential Demands Included In Projections? Yes

Submittal Table 4-5 Retail: Water Loss Audit Reporting
Public Water System ID # Reporting Period Submitted to DWR Water Loss Audit Program
CA1910126 2020 Yes
CA1910126 2021 Yes
CA1910126 2022 Yes
CA1910126 2023 Yes
CA1910126 2024 Yes
CA1910126 2025 Yes
Notes: The “Volume of Water Loss” quantities for CY 2020 through CY 2024 were obtained from the annual AWWA Water Loss Audits (and based on the combination of apparent losses and real losses). The AWWA Water Loss Audits were reported on a calendar year basis.

Submittal Table 4-6 Retail: Progress Towards 2028 Water Loss Standard Public Water
System ID #
Reported in
Submittal Table
2-1 R
Did the Water
Board Calculate
a Water Loss
Standard for this
Public Water
System?
Real Water Loss
State Water
Board Standard
2028 Real Water
Loss Standard
per Unit per day
Real Water Loss
State Water
Board Standard
Units for Real
Water Loss
Real Water Loss
Most Recent
AWWA Water
Loss Audit
Number of Units
(Connections or
Miles
corresponding
with units
selected)
Real Water Loss
Most Recent
AWWA Water
Loss Audit
Volume of Total
Real Loss (AF)
(from AWWA
Water Loss
Audit)
Real Water Loss
Per Unit per Day
Apparent Water
Loss
State Water
Board Standard
2028 Apparent
Water Loss
Standard per
Unit per Day
Apparent Water
Loss
State Water
Board Standard
Units for
Apparent Water
Loss
Apparent Water
Loss
Most Recent
AWWA Water
Loss Audit
Number of
Connections
Apparent Water
Loss
Most Recent
AWWA Water
Loss Audit
Volume of Total
Apparent Loss
(AF)
(from AWWA
Water Loss
Audit)
Apparent Water
Loss Per Unit per
Day
CA1910126 Yes 21.7
Gallons per
Service
Connection per
Day (GPSCD)
30,796 493 14.3 13.1
Gallons per
Service
Connection per
Day (GPSCD)
30,769 923 26.8
Water Board's Calculated Water Loss Standards
Submittal Table 5-1 Retail: SB X7-7 2020 Target Progress Was Supplier
part of a
merger or
consolidation
since 2020?
Regional
Alliance
Target or
Individual
Target?
2020 Target Actual
2020 GPCD
Did
Supplier
Achieve
Targeted
Reduction
for 2020?
Actual
2025 GPCD
(From SB
X7-7
Compliance
Form) *
Did Supplier
meet the
2020 Target
in 2025? *
n/a n/a 147 113 Yes 105 Yes
Notes: n/a=Not Applicable
* Only for suppliers that did not meet the Target in 2020

Submittal Table 6-1 Retail: Groundwater Volume Pumped
Groundwater
Type
Potable or
Non-
Potable
(OPTIONAL)
Location
or Basin
Name
2021 (AF) 2022 (AF) 2023 (AF) 2024 (AF) 2025 (AF)
Alluvial Basin Potable Chino
Basin
9,182 10,159 10,189 10,449 9,796
Alluvial Basin Potable Six Basins 3,447 3,120 2,075 3,066 3,792 Total 12,629 13,279 12,264 13,515 13,588
Submittal Table 6-2 Retail: Wastewater Collected Within Service Area Wastewater
Collection
Name of
Wastewater
Collection Agency
Wastewater Collection
Wastewater Volume
Metered or Estimated?
Optional
Wastewater Collection
Volume of Wastewater
Collected from UWMP
Service Area 2025 (AF)
Recipient of Collected
Wastewater
Name of Wastewater
Treatment Plant (WWTP) and
Place ID Number
Recipient of Collected
Wastewater
Is WWTP Located
Within UWMP Area?
Sanitation Districts of
Los Angeles County Metered 7,672 Pomona Water Reclamation Plant, Place ID 250700 No

Total Wastewater
Received from UWMP
Service Area in 2025:
7,672

Submittal Table 6-3 Retail: Wastewater Treatment and Outcomes Within UWMP Service Area Wastewater
Treatment
Plant Name
and Place ID
Number
Does This
Plant Treat
Wastewater
Generated
Outside the
UWMP
Service
Area?
(Optional)
2025 Volume
of
Wastewater
Received
from UWMP
Service Area
(AF)
Total 2025
Volume of
Water
Treated (AF)
2025
Outcomes of
Treated
Wastewater
Water
Recycled
Within
UWMP
Service Area
Treatment
Level
2025
Outcomes of
Treated
Wastewater
Water
Recycled
Within
UWMP
Service Area
Volume (AF)
2025
Outcomes of
Treated
Wastewater
Water
Recycled
Outside of
UWMP
Service Area
Treatment
Level
2025
Outcomes of
Treated
Wastewater
Water
Recycled
Outside of
UWMP
Service Area
Volume (AF)
2025
Outcomes of
Treated
Wastewater
Effluent
Discharge
that is not a
Permitted
Recycled
Water Use
Treatment
Level
2025
Outcomes of
Treated
Wastewater
Effluent
Discharge
that is not a
Permitted
Recycled
Water Use
Volume (AF)
2025
Outcomes of
Treated
Wastewater
Required
Discharge for
Instream
Flow
Treatment
Level
2025
Outcomes of
Treated
Wastewater
Required
Discharge for
Instream
Flow
Volume (AF)
2025
Outcomes of
Treated
Wastewater
Delivered to
Another
Entity for
Additional
Treatment
Treatment
Level
2025
Outcomes of
Treated
Wastewater
Delivered to
Another
Entity for
Additional
Treatment
Volume (AF)
2025
Outcomes of
Treated
Wastewater
Delivered to
Another
Entity for
Additional
Treatment
Name of
other entity
Pomona
Water
Reclamation
Plant, Place
ID 250700
Yes 7,672 4,987 Tertiary 1,423 3,564
Total 7,672 4,987 1,423 3,564 0 0 0
Submittal Table 6-4 Retail: Recycled Water Direct Beneficial Uses Within Service Area Use Type
Potable or
Non-Potable
(after
treatment if
treated)
(Optional)
Additional
Information
2025
(AF)
2030
(AF)
2035
(AF)
2040
(AF)
2045
(AF)
2050
(AF)
Potential
Recycled
Water
Use
Volume
Potential
Recycled Water
Use
Narrative page
number
(Optional)
Landscape
irrigation
(exc golf
courses)
Non-Potable
Agricultural
and landscape
irrigation,
ornamental
plant
irrigation,
impoundment,
and athletic
field irrigation
1,423 1,874 1,874 1,874 1,874 1,874
Subtotal
Potable 0 0 0 0 0 0 0
Subtotal Non-
Potable 1,423 1,874 1,874 1,874 1,874 1,874 0
Total 1,423 1,874 1,874 1,874 1,874 1,874 0 0
Submittal Table 6-5 Retail: 2020 UWMP Recycled Water Use Projection Compared to 2025 Actual Use Type 2020 Projection for 2025 (AF) 2025 Actual Use (AF) Landscape irrigation (exc golf courses) 2,350 1,423

Total 2,350 1,423
Notes:

Submittal Table 6-6 Retail: Methods to Encourage Future Recycled Water Use Name of
Action Description Planned
Implementation Year
Expected Increase
in Recycled Water
Use (AF)
Recycled
Water Master
Plan
Potential recycled water demands
identified in City of Pomona's 2009
Water Master Plan
Future
Draft Water,
Sewer and
Recycled
Water
Strategic Plan
Implement recommendations from
Water, Sewer and Recycled Water
Strategic Plan
Future

Total (AF) 0
Unit Conversion to AF 0
Notes: A narrative explanation is provided in Section 4.5.1 of the UWMP.

Submittal Table 6-7 Retail: Expected Future Water Supply Projects or Programs Name of
Future Projects
or Programs
Joint Project
with other
suppliers?
If Yes, Supplier
Name
Additional
Description
Potable or
Non-Potable
(after treatment
if treated)
(OPTIONAL)
Planned
Implementation
Year
Planned for
Use in Year
Type
Expected
Increase in
Water Supply
to Supplier
(AF)
Pomona
Combined
Project
No
Implement
groundwater
quality
improvement
measures,
including Anion
Exchange Plant
and
enhancements
to Reservoir 5
Ongoing Average Year 5,300
Notes: There are future water supply projects or programs not compatible with this table; therefore, are described in narrative form in Section

4.7 of the UWMP.

Submittal Table 6-8 Retail: Water Supplies — Actual
Water Supply Additional Description
2025 Potable or
Non-Potable
(after treatment
if treated)
(Optional)
2025 Actual
Volume
(AF)
2025 Total
Entitlement
(AF)
(Optional)
Groundwater (not
desalinated) Chino Basin 9,796 Potable
Groundwater (not
desalinated) Six Basins 3,792 Potable
Surface Water San Antonio Creek 1,683 Potable
Recycled Water Pomona Water
Reclamation Plant 1,849 Non-Potable
Purchased or Imported
Water
Metropolitan Water
District – TVMWD 3,027 Potable
Subtotal Potable 18,298 0
Subtotal Non-
Potable 1,849 0
Total 20,147 0
Submittal Table 6-9 Retail: Water Supplies — Projected
Water Supply Additional Detail on
Water Supply
Potable or Non-
Potable (after
treatment if
treated)
(OPTIONAL)
Projected
Water Supply
2030
Reasonably
Available
Volume (AF)
Projected
Water Supply
2030
Total
Entitlement
(AF)
(Optional)
Projected
Water Supply
2035
Reasonably
Available
Volume (AF)
Projected
Water Supply
2035
Total
Entitlement
(AF)
(Optional)
Projected
Water Supply
2040
Reasonably
Available
Volume (AF)
Projected
Water Supply
2040
Total
Entitlement
(AF)
(Optional)
Projected
Water Supply
2045
Reasonably
Available
Volume (AF)
Projected
Water Supply
2045
Total
Entitlement
(AF)
(Optional)
Projected
Water Supply
2050
Reasonably
Available
Volume (AF)
Projected
Water Supply
2050
Total
Entitlement
(AF)
(Optional)
Groundwater
(not
desalinated)
Chino Basin Potable 10,050 9,970 9,800 9,555 9,239 Groundwater
(not
desalinated)
Six Basins Potable 3,216 3,190 3,136 3,057 2,956
Surface Water San Antonio Creek Potable 1,691 1,674 1,649 1,616 1,576 Recycled Water Pomona Water
Reclamation Plant Non-Potable 1,874 1,874 1,874 1,874 1,874 Purchased or
Imported
Water
Metropolitan Water
District – Three Valleys
Municipal Water
District
Potable 3,315 3,408 3,458 3,617 3,876
Subtotal Potable 18,273 0 18,242 0 18,043 0 17,845 0 17,647 0 Subtotal Non-
Potable 1,874 1,874 1,874 1,874 1,874 0
Total 20,147 0 20,116 0 19,917 0 19,719 0 19,521 0

Optional Submittal Table 7-1 Retail: Basis of Water Year Data (Reliability Assessment) Year Type Base Year Volume Available
(AF)
Percent of Average
Supply
Average Year 2021-2025 20,327 100%
Single-Dry Year 2021 22,029 108%
Consecutive Dry Years 1st Year 2018 21,276 105%
Consecutive Dry Years 2nd Year 2019 19,782 97%
Consecutive Dry Years 3rd Year 2020 21,174 104%
Consecutive Dry Years 4th Year 2021 22,029 108%
Consecutive Dry Years 5th Year 2022 20,981 103%

Submittal Table 7-2 Retail: Normal Year Supply and Use Comparison Total Type 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF) Supply totals 20,147 20,116 19,917 19,719 19,521
Use totals 20,147 20,116 19,917 19,719 19,521
Difference 0 0 0 0 0
Notes: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in UWMP Table 2-6 (DWR Submittal Table 4-2R). The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in UWMP Table 4-5 (DWR Submittal Table 6-9R).

Submittal Table 7-3 Retail: Single Dry Year Supply and Use Comparison Total Type 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF) Supply totals 21,834 21,801 21,585 21,370 21,156
Use totals 21,834 21,801 21,585 21,370 21,156
Difference 0 0 0 0 0
Notes: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in UWMP Table 2-6 (DWR Submittal Table 4-2R). The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in UWMP Table 4-5 (DWR Submittal Table 6-9R).

Submittal Table 7-4 Retail: Multiple Dry Years Supply and Use Comparison Year Total Type /
Difference 2030 (AF) 2035 (AF) 2040 (AF) 2045 (AF) 2050 (AF) Supply totals 21,087 21,055 20,847 20,640 20,432
First year Use totals 21,087 21,055 20,847 20,640 20,432 Difference 0 0 0 0 0
Supply totals 19,607 19,577 19,383 19,190 18,998
Second year Use totals 19,607 19,577 19,383 19,190 18,998 Difference 0 0 0 0 0
Supply totals 20,986 20,954 20,747 20,541 20,334
Third year Use totals 20,986 20,954 20,747 20,541 20,334 Difference 0 0 0 0 0
Supply totals 21,834 21,801 21,585 21,370 21,156
Fourth year Use totals 21,834 21,801 21,585 21,370 21,156 Difference 0 0 0 0 0
Supply totals 20,795 20,763 20,558 20,353 20,149
Fifth year Use totals 20,795 20,763 20,558 20,353 20,149 Difference 0 0 0 0 0
Notes: The supply and demand totals presented in this table reflect an aggregation of both the potable and non-potable water systems. Therefore, the total demand shown here exceeds the potable-only demand projected in UWMP Table 2-6 (DWR Submittal Table 4-2R). The total demand in this reliability assessment includes those potable demands plus the projected non-potable (recycled water) demands, which are scaled to be met 1-to-1 by the recycled water supplies detailed in UWMP Table 4-5 (DWR Submittal Table 6-9R).

Submittal Table 7-5 Retail: Five-Year Drought Risk Assessment Totals 2026 2027 2028 2029 2030
Total Water Use (AF) 21,087 19,607 20,986 21,834 20,795 Total Supplies (AF) 21,087 19,607 20,986 21,834 20,795
Difference w/o WSCP Action (AF) 0 0 0 0 0

Submittal Table 8-1: Cross-reference for Standard vs Supplier Shortage Levels Standard Shortage
Levels
Percent Shortage
Range
Suppliers Shortage
Levels
Percent Shortage
Range
1 Up to 10%
2 Up to 20%
3 Up to 30%
4 Up to 40%
5 Up to 50%
6 >50%
Notes: The Supplier uses the standard six levels of water shortage; therefore, supplier‑specific shortage levels and percentage ranges are not separately identified in this table.

Submittal Table 8-2 Retail: Supply Augmentation and Other Actions Shortage
Level
Supply Augmentation
Methods and Other
Actions by Water
Supplier
How much is this
going to reduce the
shortage gap?
(Percentage)
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional
Explanation or
Reference
(Optional)
1 Transfers Not applicable (see
notes)
2 Transfers Not applicable (see
notes)
3 Transfers Not applicable (see
notes)
4 Transfers Not applicable (see
notes)
5 Transfers Not applicable (see
notes)
6 Transfers Not applicable (see
notes)
Notes: The City will consider increased production from Six Basins and the Chino Basin using existing facilities to address increased demands. As noted in Table 2 of the WSCP (Part 4 Appendix D7), the City plans to implement demand reduction measures in the event water supplies from existing sources are not sufficient to meet anticipated demands.

Submittal Table 8-3 Retail: Demand Reduction Actions
Shortage
Level
Demand Reduction
Actions
How much is
this going to
reduce the
shortage gap?
Volume or
Percentage
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional Explanation or Reference
(Optional)
Penalty, Charge,
or Other
Enforcement?
1 Landscape - Restrict or
prohibit runoff from
landscape irrigation
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
No excessive runoff. Yes
1 Landscape - Prohibit
certain types of
landscape irrigation
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
No watering/irrigating for more
than 15 min/day/station. Yes
1 CII - Lodging
establishment must
offer opt out of linen
service
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Yes
1 CII - Commercial
kitchens required to
use pre-rinse spray
valves
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Yes
1 Water Features -
Restrict water use for
decorative water
features, such as
fountains
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Water features must operate with
recirculated water. Yes
Shortage
Level
Demand Reduction
Actions
How much is
this going to
reduce the
shortage gap?
Volume or
Percentage
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional Explanation or Reference
(Optional)
Penalty, Charge,
or Other
Enforcement?
1 Other - Prohibit use of
potable water for
washing hard surfaces
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Exceptions for hand-held bucket or
similar container or a hand- held
hose equipped with a positive self -
closing water shut-off nozzle or
device
Yes
1 Other - Prohibit vehicle
washing except at
facilities using recycled
or recirculating water
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Exceptions for hand-held bucket or
similar container or a hand- held
hose equipped with a positive self-
closing water shut-off nozzle or
device
Yes
1 Other - Customers must
repair leaks, breaks,
and malfunctions in a
timely manner
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Must be repaired within 72 hours
of notification. Yes
1 Landscape - Limit
landscape irrigation to
specific days
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Maximum 3 days a week. Yes
1 Increase Frequency of
Meter Reading
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
Per evaluation of annual water loss
audits. No
1 Implement or Modify
Drought Rate Structure
or Surcharge
Volume Collective reduction
from all Shortage
Level 1 actions is up
to 1,814 AFY
At the sole discretion of City
Council. Yes
Shortage
Level
Demand Reduction
Actions
How much is
this going to
reduce the
shortage gap?
Volume or
Percentage
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional Explanation or Reference
(Optional)
Penalty, Charge,
or Other
Enforcement?
2 Other
Volume Collective reduction
from Shortage Level 1
plus all Shortage
Level 2 actions is up
to 3,627 AFY
All actions under Shortage Level 1 Yes
2 Landscape - Limit
landscape irrigation to
specific days
Volume Collective reduction
from all Shortage
Level 2 actions is up
to 3,627 AFY
Maximum 2 days a week. Yes
2 Other water feature or
swimming pool
restriction
Volume Collective reduction
from all Shortage
Level 2 actions is up
to 3,627 AFY
Filling ornamental, lakes, ponds,
pools, or spas is prohibited. Yes
2 Other - Customers must
repair leaks, breaks,
and malfunctions in a
timely manner
Volume Collective reduction
from all Shortage
Level 2 actions is up
to 3,627 AFY
Must be repaired within 48 hours
of notification. Yes
3 Other
Volume Collective reduction
from Shortage Level 2
plus all Shortage
Level 3 actions is up
to 5,441 AFY
All actions under Shortage Level 2 Yes
Shortage
Level
Demand Reduction
Actions
How much is
this going to
reduce the
shortage gap?
Volume or
Percentage
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional Explanation or Reference
(Optional)
Penalty, Charge,
or Other
Enforcement?
4 Other
Volume Collective reduction
from Shortage Level 3
plus all Shortage
Level 4 actions is up
to 7,254 AFY
All actions under Shortage Level 3 Yes
4 Moratorium or Net
Zero Demand Increase
on New Connections
Volume Collective reduction
from all Shortage
Level 4 actions is up
to 7,254 AFY
The City may decide not to provide
new service or discontinue water
service.

Yes
4 Landscape - Prohibit all
landscape irrigation
Volume Collective reduction
from all Shortage
Level 4 actions is up
to 7,254 AFY
Yes
4 Other - Customers must
repair leaks, breaks,
and malfunctions in a
timely manner
Volume Collective reduction
from all Shortage
Level 4 actions is up
to 7,254 AFY
Must be repaired within 24 hours
of notification. Yes
5 Other
Volume Collective reduction
from Shortage Level 4
plus all Shortage
Level 5 actions is up
to 9,068 AFY
All actions under Shortage Level 4 Yes
Shortage
Level
Demand Reduction
Actions
How much is
this going to
reduce the
shortage gap?
Volume or
Percentage
How much is this
going to reduce the
shortage gap?
Shortage Gap
Reduction Value (AF)
Additional Explanation or Reference
(Optional)
Penalty, Charge,
or Other
Enforcement?
6 Other
Volume Collective reduction
from Shortage Level 5
plus all Shortage
Level 6 actions is
greater than 9,068
AFY
All actions under Shortage Level 5 Yes

Submittal Table 10-1 Retail: Notification to Cities and Counties City or County Name 60 Day Notice Notice of Public Hearing Claremont Yes Yes
Pomona Yes Yes
Upland Yes Yes
Los Angeles County Yes Yes

2025 Part 4: City of Pomona Appendix D

D6: AWWA Water Audits
The following AWWA Water Audit reports are available online. Select the links below to view each report:
• 2020 AWWA Water Audit
• 2021 AWWA Water Audit
• 2022 AWWA Water Audit
• 2023 AWWA Water Audit
• 2024 AWWA Water Audit
If a link is not available, AWWA Water Audit reports for all years can be downloaded from the WUEdata website.
2025 Part 4: City of Pomona Appendix D

D7: Water Shortage Contingency Plan

2025 WATER SHORTAGE

CONTINGENCY PLAN

CITY OF POMONA
2025 Water Shortage Contingency
Plan
City of Pomona Page 1

ACRONYMS AND ABBREVIATIONS

Acronym Description
AF Acre‑Foot
AFY Acre‑Feet per Year
CII Commercial, Industrial, and Institutional
City City of Pomona
CWC California Water Code
DMM Demand Management Measure
DWR California Department of Water Resources
ERP Emergency Response Plan
FEMA Federal Emergency Management Agency
FY Fiscal Year
IEUA Inland Empire Utilities Agency
LACSD Los Angeles County Sanitation Districts
MWD Metropolitan Water District of Southern California
RRA Risk and Resilience Assessment
SWP State Water Project
TVMWD Three Valleys Municipal Water District
USEPA United States Environmental Protection Agency
UWMP Urban Water Management Plan
WSAP Water Supply Allocation Plan
WSCP Water Shortage Contingency Plan

2025 Water Shortage Contingency
Plan
City of Pomona Page 2

WATER SHORTAGE CONTINGENCY PLAN
The City of Pomona’s (City) Water Shortage Contingency Plan (WSCP) discusses and provides the following:
• The City’s WSCP is a detailed approach which presents how the City intends to act, or respond, in the case of an actual water shortage contingency. • Preparation of the City’s “Annual Water Supply and Demand Assessment” (Annual Assessment) is discussed. Beginning July 1, 2022, the City has submitted the Annual Assessment every year through 2025. The Annual Assessment includes a review of the City’s “unconstrained” water demands for the current year and for a potential upcoming single dry year. Unconstrained water demands represent the City’s water demands prior to any “response actions” the City may invoke pursuant to the City’s WSCP.
• The City will manage water supplies to minimize the adverse impacts of water shortages. The City’s plan for water usage during periods of shortage is designed to incorporate six standard water shortage levels including up to 10, 20, 30, 40, and 50 percent shortages, and greater than a 50 percent shortage. • For each declared water supply shortage level, customers will be required to reduce their consumption by the percentage specified in the corresponding water supply shortage level.

WATER SHORTAGE CONTINGENCY PLAN

LAY DESCRIPTION
City of Pomona Page 2
2025 Water Shortage Contingency
Plan

• For each declared water supply shortage level, the City has established response actions to reduce demand on water supplies and to reduce any shortage gaps in water supplies. These demand reduction actions include irrigation and other outdoor use restrictions, rate structure changes, and other water use prohibitions. • The operational changes the City will consider in addressing water shortages on a short-term basis are discussed and include improved monitoring, analysis, and tracking of customer water usage to enforce demand reduction measures. • The City’s Emergency Response Plan (ERP) is summarized. The ERP provides the management, procedures, and designated actions the City and its employees will implement during emergency situations (including catastrophic water shortages) resulting from natural disasters, system failures, and other unforeseen circumstances.
• The preparation of the City’s seismic risk assessment and mitigation plan is discussed. The locations of earthquake faults in the vicinity of the City’s water service area are provided.
• The effectiveness of the shortage response actions for each of the City’s standard water shortage levels is presented. The City has been able to provide sufficient water supplies to its customers, including during long-term droughts and years with historically high water demands.
• The communication protocols implemented by the City when it declares any water shortage level are presented.
• The compliance and enforcement procedures associated with City’s standard water shortage levels are presented.
• The legal authorities associated with City’s standard water shortage levels are presented.
• The financial consequences associated with City’s standard water shortage levels are presented.
• The City will evaluate the need for revising the WSCP in order to resolve any water shortage gaps, as necessary. The steps necessary for the City to adopt and amend its WSCP are presented.

City of Pomona Page 3
2025 Water Shortage Contingency
Plan

The following WSCP includes references to Chapters and Sections from the City’s 2025 Urban Water Management Plan (UWMP):

1 WATER SUPPLY RELIABILITY ANALYSIS
_

CWC 10632.

(a)(1) The analysis of water supply reliability conducted pursuant to Section 10635.

The City’s sources of supply were discussed in Chapter 4 of the 2025 UWMP and consist of groundwater from Six Basins, groundwater from Chino Basin, groundwater from Spadra Basin, treated surface water from San Antonio Creek, treated imported water purchased from Metropolitan Water District of Southern California (MWD) through Three Valleys Municipal Water District (TVMWD), and recycled water purchased from the Los Angeles County Sanitation Districts (LACSD). The City provides recycled water for irrigation in lieu of potable water supplies. Both Six Basins and Chino Basin are adjudicated, and groundwater supplies are managed. The reliability of the various sources of su pply is discussed in Chapter 5 of the 2025 UWMP. Based on the adjudication provisions in the two groundwater basins, the City is able to produce groundwater without limitation, provided an applicable assessment is paid to the respective Watermaster service to purchase untreated imported water for groundwater replenishment. Imported water supplies (both treated and untreated) may be impacted in the event MWD implements its Water Supply Allocation Plan ( WSAP) due to a water supply shortage. Finally, recycled water is locally generated and is not impacted by drought conditions.

City of Pomona Page 4
2025 Water Shortage Contingency
Plan

2 ANNUAL WATER SUPPLY AND DEMAND ASSESSMENT PROCEDURES

CWC 10632.

(a)(2) The procedures used in conducting an annual water supply and demand assessment that include, at a minimum, both of the following:

(A) The written decision-making process that an urban water supplier will use each year to determine its water supply reliability.

(B) The key data inputs and assessment methodology used to evaluate the urban water supplier’s water supply reliability for the current year and one dry year, including all of the following:

(i) Current year unconstrained demand, considering weather, growth, and other influencing factors, such as policies to manage current supplies to meet demand objectives in future years, as applicable.

(ii) Current year available supply, considering hydrological and regulatory conditions in the current year and one dry year. The annual supply and demand assessment may consider more than one dry year solely at the discretion of the urban water supplier.

(iii) Existing infrastructure capabilities and plausible constraints.

(iv) A defined set of locally applicable evaluation criteria that are consistently relied upon for each annual water supply and demand assessment.

(v) A description and quantification of each source of water supply.

CWC 10632.1.

An urban water supplier shall conduct an annual water supply and demand assessment pursuant to subdivision (a) of Section 10632 and, on or before July 1 of each year, submit an annual water shortage assessment report to the department with information for anticipated shortage, triggered shortage response actions, compliance and enforcement actions, and communication actions consistent with the supplier’s water shortage contingency plan. An urban water supplier that relies on imported water from the State Water Project or the Bureau of Reclamation shall submit its annual water supply and demand assessment within 14 days of receiving its final allocations, or by July 1 of each year, whichever is later.

Beginning July 1, 2022, the City has submitted an Annual Assessment in accordance with Department of Water Resources’ (DWR) guidance and requirements. The Annual Assessment include s a review of the City’s unconstrained water demands (i.e. water demands prior to any projected response actions the City may trigger under this WSCP) for the current year and the upcoming (potential single dry) year. The City also includes information regarding anticipated shortages, triggered shortage response actions, City of Pomona Page 5
2025 Water Shortage Contingency
Plan

compliance and enforcement actions, and communication actions consistent with the City’s WSCP.

For each Annual Assessment, the City prepare s a preliminary assessment which evaluates the adequacy of its water supplies for the current and upcoming years by April of each year. The preliminary assessment includes a review of water supplies for at least a single dry year.

The components of an Annual Assessment consist of the following:
• A written decision-making process
• Key data inputs and assessment methodology

2.1 DECISION MAKING PROCESS

The City produces groundwater from the Chino Basin, Spadra Basin, and Six Basins as its primary sources of water supply and these basins are managed on a fiscal year (FY) basis. Consequently, during the third quarter of each fiscal year, the City reviews its water demands from the initial six months along with the current groundwater basin conditions and local hydrology. This information is used to help develop the Annual Assessment.

The City c ompares total demand to total supply to identify potential shortages. If shortages are identified, the City will determine the necessary WSCP level and corresponding reduction. A draft of the Annual Assessment is circulated internally within the City for peer review and comment. Based on comments received, a redraft is prepared and provided to City managers during the Spring of each year. The draft is subsequently provided to the City Manager for final review. Subsequently, a final draft of the Annual Assessment is provided to the City Council for review and included in the agenda as part of a City Council meeting such that it can be approved, and any recommended specific shortage response actions may be enacted. The final Annual Assessment is provided to DWR no later than July 1 of each year.

The Annual Assessment is instrumental in providing guidance to the City for decisions regarding potential declarations of a water supply shortage and implementation of water reduction stages, instituting mandatory water restrictions, promoting water use efficiency City of Pomona Page 6
2025 Water Shortage Contingency
Plan

and conservation programs, water rates and drought rate surcharges, and the necessity of pursuing alternative water supplies. This process ensure s adequate water supply resources are available to the City.

2.2 DATA AND METHODOLOGIES

The key data inputs and methodologies that are evaluated by the City during the preparation of the preliminary assessment will include the following:

1) Evaluation Criteria: The locally applicable evaluation criteria used to prepare the Annual Assessment are identified. The evaluation criteria includes, but is not limited to, an analysis of current local hydrology (including rainfall and groundwater levels), current water demands, a review of water system improvement plans which may impact infrastructure availability, and water quality regulations which may impact groundwater availability.

2) Water Supply: A description of each available water supply source is provided. The descriptions includes a quantification of each available water supply source and are based on review of current production capacities, historical production, UWMPs, and prior water supply studies (including Water Supply Assessments and/or Master Plans).
3) Unconstrained Water Demand: The potential unconstrained water demands during the current year and the upcoming (potential single dry) year, prior to any special shortage response actions, are reviewed. The review include s factors such as weather, existing and projected land uses and populations, actual customer consumption and water use factors, monthly Urban Water Supplier Reports, existing water shortage levels (see Section 3), and existing water conservation ordinances (see Section 8.1.1 of the UWMP).

4) Planned Water Use for Current Year Considering Dry Subsequent Year: The water supplies available to meet the demands during the current year and the upcoming (potential single dry) year are considered and identified for each source of supply.

The evaluation include s factors such as estimated water demands, weather, City of Pomona Page 7
2025 Water Shortage Contingency
Plan

groundwater basin operating safe yields, water quality results, existing available pumping capacities, imported water allocations, contractual obligations, regulatory issues, use of emergency interconnections, and the costs associated with producing each water supply source.

5) Infrastructure Considerations : The capabilities of the water distribution system infrastructure to meet the water demands during the current year and the upcoming (potential single dry) year are considered. Available production capacities (e.g. groundwater well capacities) and distribution system water losses (see Section

2.1.2 of the UWMP ) are reviewed. In addition, capital improvement and replacement projects, as well as potential projects which may increase water system and production capacities (see Section 4.7 of the UWMP ), will be considered.

6) Other Factors : Additional local considerations, if any, which can affect the availability of water supplies are described.

3 SIX STANDARD WATER SHORTAGE LEVELS

CWC 10632.

(a)(3)(A) Six standard water shortage levels corresponding to progressive ranges of up to 10, 20, 30, 40, and 50 percent shortages and greater than 50 percent shortage. Urban water suppliers shall define these shortage levels based on the suppliers’ water supply conditions, including percentage reductions in water supply, changes in groundwa ter levels, changes in surface elevation or level of subsidence, or other changes in hydrological or other local conditions indicative of the water supply available for use.

Shortage levels shall also apply to catastrophic interruption of water supplies, i ncluding, but not limited to, a regional power outage, an earthquake, and other potential emergency events.
(a)(3)(B) An urban water supplier with an existing water shortage contingency plan that uses different water shortage levels may comply with the requirement in subparagraph (A) by developing and including a cross reference relating its existing categories to the six standard water shortage levels.

The City will manage water supplies to prudently minimize the adverse impacts of water shortages. The City’s plan for water usage during periods of shortage is designed to incorporate six standard water shortage levels corresponding to progressive ranges from up to a 10, 20, 30, 40, and 50 percent shortages, and greater than a 50 percent shortage.

City of Pomona Page 8
2025 Water Shortage Contingency
Plan

For each declared water supply shortage level, customers will be required to reduce their consumption by the percentage specified in the corresponding water supply shortage level. The required percentage reduction for each customer will be based on water usage during the same billing period in the last calendar year during which there were no declared water shortages.

The City’s Ordinance No. 4122 (“Water Conservation and Water Supply Shortage Program and Regulations”), adopted in June 2009, previously established three (3) water shortage levels. A copy of Ordinance No. 4122 is provided in Appendix A. In accordance with the CWC in which urban water suppliers are required to define six standard water shortage levels, the City has developed the crosswalk illustrated below that translates the City’s previously established shortage levels to the mandated standard shortage levels.

The shortage level changes were made in 2020 and have remained the same for 2025.

Note: The 2020 shortage levels have remained the same for 2025.

Table 1 provides a description of the six standard water shortage levels which may be triggered by a shortage in one or more of the City’s water supply sources, depending on the severity of the shortage and its anticipated duration.

City of Pomona Page 9
2025 Water Shortage Contingency
Plan

Table 1. Water Shortage Contingency Planning Levels

Submittal Table 8-1 Water Shortage Contingency Plan Levels Shortage
Level
Percent
Shortage Range
Shortage Response Actions
(Narrative description)
1 Up to 10%
Watering or irrigating is limited to a maximum of 3 days per week during April through October and a maximum of 1 day per week during November through March. All leaks, breaks, or other malfunctions must be repaired within 72 hours.

In addition, actions include implementation of other prohibitions, restrictions, or operational changes on water use as determined by the City. These actions include, but are not limited to, an increase in the water rate structure and increased performance of customer water loss audits.
2 Up to 20%
In addition to Shortage Level 1, actions include increased limitation on watering or irrigating; all leaks, breaks, or other malfunctions must be repaired within 48 hours; Limits on filling ornamental lakes, washing vehicles, and filling residential swimming pools and spas.
3 Up to 30%
In addition to Shortage Level 2, actions include implementation of other prohibitions, restrictions, or operational changes on water use as determined by the City. These actions include, but are not limited to, an increase in the water rate structure and increased performance of customer water loss audits. 4 Up to 40%
In addition to Shortage Level 3, actions include restrictions on watering or irrigating and all leaks, breaks, or other malfunctions must be repaired within 24 hours. The City in its sole discretion may decide not to provide new potable water service or may discontinue service.
5 Up to 50%
In addition to Shortage Level 4, actions include implementation of other prohibitions, restrictions, or operational changes on water use as determined by the City. These actions include, but are not limited to, an increase in the water rate structure and increased performance of customer water loss audits. 6 >50%
In addition to Shortage Level 5, actions include implementation of other prohibitions, restrictions, or operational changes on water use as determined by the City. These actions include, but are not limited to, an increase in the water rate structure and increased performance of customer water loss audits.

Notes
City of Pomona Page 10
2025 Water Shortage Contingency
Plan

4 SHORTAGE RESPONSE ACTIONS

CWC 10632.

(a)(4) Shortage response actions that align with the defined shortage levels and include, at a minimum, all of the following:

(A) Locally appropriate supply augmentation actions.

(B) Locally appropriate demand reduction actions to adequately respond to shortages.

(C) Locally appropriate operational changes.

(D) Additional, mandatory prohibitions against specific water use practices that are in addition to state-mandated prohibitions and appropriate to the local conditions.

(E) For each action, an estimate of the extent to which the gap between supplies and demand will be reduced by implementation of the action.

Shortage response actions are dependent on the severity of a declared shortage level.

Response actions implement varying improvements and regulations of system infrastructure and operations, water supply augmentation, demand reduction initiatives and other water use functions to conserve water supplies.

4.1 DEMAND REDUCTION

The City has established water shortage response actions to reduce demand on water supplies. These demand reduction actions include irrigation and other outdoor use restrictions, rate structure changes, and other water use prohibitions. Depending on the percent reduction in the City’s water supply and corresponding water shortage level, regulations have been made to conserve water and reduce the shortage gap in normal supply levels. Many demand reduction actions are applicable to all levels of water shortages while others are exclusive to certain levels of shortage. The structure of demand reduction actions under a specific water shortage level are designed to encourage those customers with high gallon per capita usage to achieve proportionally greater reduction than those with low use. Violations of these demand reduction actions may be considered waste and an unreasonable use of water. Table 2 describes each demand reduction action and its effect on reducing the shortage gap.

City of Pomona Page 11
2025 Water Shortage Contingency
Plan

The following demand reduction actions are applicable to all water shortage levels and are in effect at all times:
• Watering or irrigating of any lawn, landscape, or other vegetated area in a manner that causes or allows excessive water runoff onto an adjoining sidewalk, driveway, street, alley gutter, or ditch is prohibited.
• Watering or irrigating of lawn, landscape, or other vegetated area with potable water using a landscape irrigation system or a watering device, that is not continuously attended, is limited to no more than 15 minutes watering per day per station. This does not apply to landscape irrigation systems that exclusively use very low-flow drip type irrigation systems when no emitter produces more than two gallons of water per hour and weather-based controllers or stream rotor sprinklers that meet a 70 percent efficiency standard. Operating a water fountain or other decorative water feature that does not use recirculated water is prohibited. • Washing down hard or paved surfaces, including but not limited to sidewalks, walkways, driveways, parking areas, tennis courts, patios, or alleys, is prohibited except when necessary to alleviate safety or sanitary hazards, and then only by use of a hand-held bucket or similar container, a hand-held hose equipped with a positive self-closing water shut-off device, or a low-volume, high-pressure cleaning machine equipped to recycle any water used, or a low-volume high-pressure water broom.
• Using water to wash or clean a vehicle, including but not limited to any automobile, truck, van, bus, motorcycle, boat, motor home, or trailer, whether motorized or not is prohibited, except by use of a hand -held bucket or similar container or a hand - held hose equipped with a positive self-closing water shut-off nozzle or device, or at a commercial car washing facility that utilizes a recirculating water system.

Installation of non-recirculating water systems is prohibited in new commercial conveyor car wash, new commercial laundry systems, or new other water intensive operations as determined by the City.
• Commercial lodging establishments must provide customers with an optional daily towel and linen laundering service. Commercial lodging establishments must prominently display notice of this option in each bathroom. Contingent on available City of Pomona Page 12
2025 Water Shortage Contingency
Plan

funding and materials as determined by the City in its sole discretion, the City will annually provide display materials to establishments for notice on these items. • Food preparation establishments are prohibited from using non -water conserving dish wash spray valves.
• Eating or drinking establishments, including but not limited to a restaurant, hotel, cafe, cafeteria, bar, club, or other public place where food or drinks are sold, served, or offered for sale, are prohibited from providing drinking water to any person unless expressly requested.

Water Supply Shortage Level 1:

• Limits on Watering Days: Watering or irrigating of lawn, landscape, or other vegetated area with potable water during the months of April through October is limited to three days per week on a schedule established by the City. (By way of example - Odd addresses on Monday, Wednesday, and Friday; even addresses on Tuesday, Thursday, and Saturday.) During the months of November through March, watering or irrigating of lawn, landscape, or other vegetated area with potable water is limited to no more than one da y per week on a schedule established and noticed by the City. (By way of example - Odd addresses on Tuesday, even addresses on Thursday.) This provision does not apply to landscape irrigation zones that exclusively use very low flow drip type irrigation systems when no emitter produces more than two gallons of water per hour. This provision also does not apply to watering or irrigating by use of a hand-held bucket or similar container, a hand-held hose equipped with a positive self-closing water shut-off nozzle or device, or for very short periods of time for the express purpose of adjusting or repairing an irrigation system.
• Obligation to Fix Leaks, Breaks, or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within seventy-two (72) hours of notification by the City unless other arrangements are made with the City.
• Other Prohibited Uses: The City may implement other prohibitions, restrictions or operational changes on water uses as determined by the City, upon reasonable City of Pomona Page 13
2025 Water Shortage Contingency
Plan

notice to customers. This includes an increase in the conservation rate structure and increased performance of water loss audits.

Water Supply Shortage Level 2:

In addition to the restrictions identified in Water Supply Shortage Level 1, the following additional water conservation requirements apply:
• Limits on Watering Days: Watering or irrigating of lawn, landscape, or other vegetated area with potable water during the months of April through October is limited to two days per week on a schedule established by the City. (By way of example - Odd addresses on Monday and Thursday, even addresses on Tuesday and Friday). During the months of November through March, watering or irrigating of lawn, landscape or other vegetated area with potable water is limited to no more than one day per week on a schedule established by the City. (By way of example - Odd addresses on Tuesday, even addresses on Thursday). This provision does not apply to landscape irrigation zones that exclusively use very low flow drip type irrigation systems when no emitter produces more than two gallons of water per hour. This provision also does not apply to watering or irrigating by use of a hand- held bucket or similar container, a hand -held hose equipped with a positive self - closing water shut -off nozzle or device, or for very short periods of time for the express purpose of adjusting or repairing an irrigation system. • Obligation to Fix Leaks, Breaks, or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within forty-eight (48) hours of notification by the City unless other arrangements are made with the City.
• Limits on Filling Ornamental Lakes or Ponds: Filling or refilling ornamental lakes or ponds is prohibited, except to the extent needed to sustain aquatic life, provided that such animals are of significant value and have been actively managed within the water feature prior to declaration of a standard Water Shortage Level 2. • Limits on Washing Vehicles: Using water to wash or clean a vehicle, including but not limited to, any automobile, truck, van, bus, motorcycle, boat, motor home, or trailer, whether motorized or not, is prohibited except by use of a hand-held bucket City of Pomona Page 14
2025 Water Shortage Contingency
Plan

or similar container, a hand-held hose equipped with a positive self -closing water shut-off nozzle or device, by high pressure/low volume wash systems, or at a commercial car washing facility that utilizes a recirculating water system to capture or reuse water.
• Limits on Filling Residential Swimming Pools and Spas: Refilling of more than one foot per week, and initial filling of residential swimming pools or outdoor spas with potable water is prohibited, except upon written authorization from the City Manager or designee.
• Other Prohibited Uses: The City may implement other prohibitions, restrictions or operational changes on water uses as determined by the City, upon reasonable notice to customers. This includes an increase in the conservation rate structure and increased performance of water loss audits.

Water Supply Shortage Level 3:

In addition to the restrictions identified in Water Supply Shortage Level 2, the following additional water conservation requirements apply:
• Limits on Watering Days: Watering or irrigating of lawn, landscape, or other vegetated area with potable water during the months of April through October is limited to two days per week on a schedule established by the City. (By way of example - Odd addresses on Monday and Thursday, even addresses on Tuesday and Friday). During the months of November through March, watering or irrigating of lawn, landscape or other vegetated area with potable water is limited to no more than one day per week on a schedule established by the City. (By way of example - Odd addresses on Tuesday, even addresses on Thursday). This provision does not apply to landscape irrigation zones that exclusively use very low flow drip type irrigation systems when no emitter produces more than two gallons of water per hour. This provision also does not apply to watering or irrigating by use of a hand- held bucket or similar container, a hand -held hose equipped with a positive self - closing water shut -off nozzle or device, or for very short periods of time for the express purpose of adjusting or repairing an irrigation system.

City of Pomona Page 15
2025 Water Shortage Contingency
Plan

• Obligation to Fix Leaks, Breaks, or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within forty-eight (48) hours of notification by the City unless other arrangements are made with the City.
• Limits on Filling Ornamental Lakes or Ponds: Filling or refilling ornamental lakes or ponds is prohibited, except to the extent needed to sustain aquatic life, provided that such animals are of significant value and have been actively managed within the water feature prior to declaration of a standard Water Shortage Level 3. • Limits on Washing Vehicles: Using water to wash or clean a vehicle, including but not limited to, any automobile, truck, van, bus, motorcycle, boat, motor home, or trailer, whether motorized or not, is prohibited except by use of a hand-held bucket or similar container, a hand-held hose equipped with a positive self-closing water shut-off nozzle or device, by high pressure/low volume wash systems, or at a commercial car washing facility that utilizes a recirculating water system to capture or reuse water. • Limits on Filling Residential Swimming Pools and Spas: Refilling of more than one foot per week, and initial filling of residential swimming pools or outdoor spas with potable water is prohibited, except upon written authorization from the City Manager or designee.
• Other Prohibited Uses: The City may implement other prohibitions, restrictions, or operational changes on water uses as determined by the City, upon reasonable notice to customers. This includes an increase in the conservation rate structure and increased performance of water loss audits.

Water Supply Shortage Level 4:

In addition to the restrictions identified in Water Supply Shortage Level 3, the following additional water conservation requirements apply:
• No Watering or Irrigating: Watering or irrigating of lawn, landscape, or other vegetated area with potable water is prohibited. This restriction does not apply to the following categories of use unless the City has determined that recycled water is available and may be lawfully applied to the use:

City of Pomona Page 16
2025 Water Shortage Contingency
Plan

a) Maintenance of vegetation excluding turf, but including trees and shrubs, that are watered using a hand-held bucket or similar container, hand-held hose equipped with a positive self-closing water shut-off nozzle or device, or a very low -flow drip type irrigation system when no emitter produces more than two gallons of water per hour subject to the watering hour restrictions;
b) Maintenance of existing landscape necessary for fire protection; c) Maintenance of existing landscape for soil erosion control; d) Maintenance of plant materials identified to be rare or essential to the wellbeing of rare animals;
e) Maintenance of landscape within active public parks and playing fields, day care centers, school grounds, cemeteries, and golf course greens, provided that such irrigation does not exceed two days per week according to the established watering schedule and time restrictions; • Obligation to Fix Leaks, Breaks or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within 24 hours of notification by the City unless other arrangements are made with the City.
• New Potable Water Service: The City, dependent on an analysis of water supply, may decide not to (a) provide new potable water service; (b) provide new temporary meters or permanent meters, and (c) issue any statements of immediate ability to serve or provide potable water service (such as, will serve letters, certificates, or letters of availability), except under the following circumstances:

a) A valid, unexpired building permit has been issued for the project; or b) The project is necessary to protect the public's health, safety, and welfare; or
c) The applicant provides substantial evidence of an enforceable commitment that water demands for the project will be offset prior to the provision of a new water meter(s) to the satisfaction of the City.

City of Pomona Page 17
2025 Water Shortage Contingency
Plan

This provision does not preclude the resetting or turn -on of meters to provide continuation of water service or the restoration of service that has been interrupted for a period of one year or less, or as determined by the City Manager or designee. • Discontinue Service: The City, in its sole discretion, may discontinue service to consumers who willfully violate provisions of this WSCP. • Other Prohibited Uses: The City may implement other prohibitions, restrictions or operational changes on water uses as determined by the City, upon reasonable notice to customers. This includes an increase in the conservation rate structure and increased water loss audits.

Water Supply Shortage Level 5:

In addition to the restrictions identified in Water Supply Shortage Level 4, the City may implement further and more restrictive water conservation measures under Water Supply Shortage Level 5. The following additional water conservation requirements apply:
• No Watering or Irrigating: Watering or irrigating of lawn, landscape or other vegetated area with potable water is prohibited. This restriction does not apply to the following categories of use unless the City has determined that recycled water is available and may be lawfully applied to the use:
a) Maintenance of vegetation excluding turf, but including trees and shrubs, that are watered using a hand-held bucket or similar container, hand-held hose equipped with a positive self-closing water shut-off nozzle or device, or a very low -flow drip type irrigation system when no emitter produces more than two gallons of water per hour subject to the watering hour restrictions;
b) Maintenance of existing landscape necessary for fire protection; c) Maintenance of existing landscape for soil erosion control; d) Maintenance of plant materials identified to be rare or essential to the wellbeing of rare animals;
e) Maintenance of landscape within active public parks and playing fields, day care centers, school grounds, cemeteries, and golf course greens, provided that such irrigation does not exceed two days per week according to the established watering schedule and time restrictions; City of Pomona Page 18
2025 Water Shortage Contingency
Plan

• Obligation to Fix Leaks, Breaks or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within 24 hours of notification by the City unless other arrangements are made with the City.
• New Potable Water Service: The City, dependent on an analysis of water supply, may decide not to (a) provide new potable water service; (b) provide new temporary meters or permanent meters, and (c) issue any statements of immediate ability to serve or provide potable water service (such as, will serve letters, certificates, or letters of availability), except under the following circumstances:
a) A valid, unexpired building permit has been issued for the project; or b) The project is necessary to protect the public's health, safety, and welfare; or
c) The applicant provides substantial evidence of an enforceable commitment that water demands for the project will be offset prior to the provision of a new water meter(s) to the satisfaction of the City.

This provision does not preclude the resetting or turn -on of meters to provide continuation of water service or the restoration of service that has been interrupted for a period of one year or less, or as determined by the City Manager or designee. • Discontinue Service: The City, in its sole discretion, may discontinue service to consumers who willfully violate provisions of this WSCP. • Other Prohibited Uses: The City may implement other prohibitions, restrictions or operational changes on water uses as determined by the City, upon reasonable notice to customers. This includes an increase in the conservation rate structure and increased water loss audits.

Water Supply Shortage Level 6:

In addition to the restrictions identified in Water Supply Shortage Level 5, the City may implement further and more restrictive water conservation measures under Water Supply Shortage Level 6. The following additional water conservation requirements apply:
• No Watering or Irrigating: Watering or irrigating of lawn, landscape, or other vegetated area with potable water is prohibited. This restriction does not apply to City of Pomona Page 19
2025 Water Shortage Contingency
Plan

the following categories of use unless the City has determined that recycled water is available and may be lawfully applied to the use:
a) Maintenance of vegetation excluding turf, but including trees and shrubs, that are watered using a hand-held bucket or similar container, hand-held hose equipped with a positive self-closing water shut-off nozzle or device, or a very low -flow drip type irrigation system when no emitter produces more than two gallons of water per hour subject to the watering hour restrictions;
b) Maintenance of existing landscape necessary for fire protection; c) Maintenance of existing landscape for soil erosion control; d) Maintenance of plant materials identified to be rare or essential to the wellbeing of rare animals;
e) Maintenance of landscape within active public parks and playing fields, day care centers, school grounds, cemeteries, and golf course greens, provided that such irrigation does not exceed two days per week according to the established watering schedule and time restrictions; • Obligation to Fix Leaks, Breaks, or Malfunctions: All leaks, breaks, or other malfunctions in the customer’s plumbing or distribution system must be repaired within 24 hours of notification by the City unless other arrangements are made with the City.
• New Potable Water Service: The City, dependent on an analysis of water supply, may decide not to (a) provide new potable water service; (b) provide new temporary meters or permanent meters, and (c) issue any statements of immediate ability to serve or provide potable water service (such as, will serve letters, certificates, or letters of availability), except under the following circumstances:
a) A valid, unexpired building permit has been issued for the project; or b) The project is necessary to protect the public's health, safety, and welfare; or
c) The applicant provides substantial evidence of an enforceable commitment that water demands for the project will be offset prior to the provision of a new water meter(s) to the satisfaction of the City.

City of Pomona Page 20
2025 Water Shortage Contingency
Plan

This provision does not preclude the resetting or turn -on of meters to provide continuation of water service or the restoration of service that has been interrupted for a period of one year or less, or as determined by the City Manager or designee. • Discontinue Service: The City, in its sole discretion, may discontinue service to consumers who willfully violate provisions of this WSCP. • Other Prohibited Uses: The City may implement other prohibitions, restrictions or operational changes on water uses as determined by the City, upon reasonable notice to customers. This includes an increase in the conservation rate structure and increased water loss audits.

Table 2. Demand Reduction Actions

Submittal Table 8-3: Demand Reduction Actions
Shortage
Level
Demand Reduction Actions
Drop down list
These are the only categories that will be accepted by
the WUEdata online submittal tool. Select those that
apply.

How much is this going to reduce the shortage gap?
Include units used (volume type or percentage)
Additional Explanation or Reference
(optional)
Penalty, Charge,
or Other
Enforcement?
For Retail Suppliers
Only
Drop Down List
1 Landscape - Restrict or prohibit runoff from
landscape irrigation
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY No excessive runoff. Yes
1 Landscape - Prohibit certain types of landscape
irrigation
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
No watering/irrigating for more than 15
min/day/station. Yes
1 CII - Lodging establishment must offer opt out
of linen service
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY Yes
1 CII - Commercial kitchens required to use pre -
rinse spray valves
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY Yes
1 Water Features - Restrict water use for
decorative water features, such as fountains
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
Water features must operate with
recirculated water. Yes
1 Other - Prohibit use of potable water for
washing hard surfaces
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
Exceptions for hand-held bucket or
similar container or a hand- held hose
equipped with a positive self-closing
water shut-off nozzle or device
Yes
1 Other - Prohibit vehicle washing except at
facilities using recycled or recirculating water
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
Exceptions for hand-held bucket or
similar container or a hand- held hose
equipped with a positive self-closing
water shut-off nozzle or device
Yes
1 Other - Customers must repair leaks, breaks,
and malfunctions in a timely manner
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
Must be repaired within 72 hours of
notification. Yes
1 Landscape - Limit landscape irrigation to
specific days
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY Maximum 3 days a week. Yes
1 Increase Frequency of Meter Reading Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY
Per evaluation of annual water loss
audits. No
1 Implement or Modify Drought Rate Structure or
Surcharge
Collective reduction from all Shortage Level 1 actions is up to 1,814 AFY At the sole discretion of City Council. Yes 2 Other Collective reduction from Shortage Level 1 plus all Shortage Level 2 actions is up to 3,627 AFY All actions under Shortage Level 1 Yes 2 Landscape - Limit landscape irrigation to
specific days
Collective reduction from all Shortage Level 2 actions is up to 3,627 AFY Maximum 2 days a week. Yes
2 Other water feature or swimming pool
restriction
Collective reduction from all Shortage Level 2 actions is up to 3,627 AFY
Filling ornamental, lakes, ponds, pools,
or spas is prohibited. Yes
City of Pomona Page 21
2025 Water Shortage Contingency
Plan

Submittal Table 8-3: Demand Reduction Actions
Shortage
Level
Demand Reduction Actions
Drop down list
These are the only categories that will be accepted by
the WUEdata online submittal tool. Select those that
apply.

How much is this going to reduce the shortage gap?
Include units used (volume type or percentage)
Additional Explanation or Reference
(optional)
Penalty, Charge,
or Other
Enforcement?
For Retail Suppliers
Only
Drop Down List
2 Other - Customers must repair leaks, breaks,
and malfunctions in a timely manner
Collective reduction from all Shortage Level 2 actions is up to 3,627 AFY
Must be repaired within 48 hours of
notification. Yes
3 Other Collective reduction from Shortage Level 2 plus all Shortage Level 3 actions is up to 5,441 AFY All actions under Shortage Level 2 Yes 4 Other Collective reduction from Shortage Level 3 plus all Shortage Level 4 actions is up to 7,254 AFY All actions under Shortage Level 3 Yes 4 Moratorium or Net Zero Demand Increase on
New Connections
Collective reduction from all Shortage Level 4 actions is up to 7,254 AFY
The City may decide not to provide new
service or discontinue water service. Yes
4 Landscape - Prohibit all landscape irrigation Collective reduction from all Shortage Level 4 actions is up to 7,254 AFY Yes
4 Other - Customers must repair leaks, breaks,
and malfunctions in a timely manner
Collective reduction from all Shortage Level 4 actions is up to 7,254 AFY
Must be repaired within 24 hours of
notification. Yes
5 Other Collective reduction from Shortage Level 4 plus all Shortage Level 5 actions is up to 9,068 AFY All actions under Shortage Level 4 Yes 6 Other Collective reduction from Shortage Level 5 plus all Shortage Level 6 actions is greater than 9,068 AFY All actions under Shortage Level 5 Yes Notes:

4.2 SUPPLY AUGMENTATION

The City does not plan to add a new source of water supply to address customer demands but instead will consider increased supplies from existing sources. Table 3 reflects this approach and does not identify any new supplies. Instead, the City will focus on demand reduction measures in the event existing sources of supply are not sufficient to meet customer demands. As discussed in Chapter 4 of the UWMP , the City’s sources of water supply include groundwater produced from the Chino Basin, Spadra Basin, and Six Basins, treated imported water purchased from MWD through TVMWD, and recycled water supplies provided by LACSD. As noted in Section 2, beginning July 1, 2022, the City has prepared and submitted an Annual Assessment which includes a review of water supplies available to meet water demands for the current and upcoming years. In the event the City is currently in, or considers entering into, one of the standard water shortage levels identified in Section 3, the City will consider the water sup ply (augmentation) actions described below.

For each water shortage level discussed in Section 3, the City will consider supplementing its existing treated imported water supplies through increased production of groundwater supplies, to the extent possible. Due to previous critically dry conditions, MWD developed the WSAP whereby available supplies are equitably allocated to its member agencies, City of Pomona Page 22
2025 Water Shortage Contingency
Plan

including TVMWD. The WSAP establishes ten different shortage levels and a corresponding drought allocation to each member agency. Based on the shortage level established by MWD, the WSAP provides a reduced drought allocation to a member agency for its Municipal and Industrial (M&I) retail demand. The ratio of MWD water supply drought allocation to local water supply will change based on the WSAP stage. The MWD drought allocation can be used to make Full Service water deliveries at the Tier 1 rate up to a Tier 1 allocation. Any Full Service water delivered in excess of a drought allocation is subject to a penalty rate in addition to the normal rate paid for the water.

In addition to the WSAP, MWD describes supply augmentation actions in its Regional 2025 UWMP, which is incorporated by reference. MWD’s primary response to any gap between core supplies (from the State Water Project (SWP) and Colorado River) and demand is to make optimal use of its supply augmentation options, consisting of drawing from flexible supply programs and storage reserves. MWD has developed and actively manages a portfolio of water supply programs including water transfer, storage, and exchange agreements. MWD pursues voluntary water transfer and exchange programs to help mitigate supply/demand imbalances and provide additional dry -year supply sources. In addition, MWD has developed significant storage capacity in reservoirs, conjunctive use, and other groundwater storage programs totaling approximately 6.0 million A F. Pursuant to MWD’s “Emergency Storage Objective”, updated in 2019 , approximately 750,000 AF of total stored water is emergency storage reserved by MWD for use in the event of supply interruptions. Based on MWD’s historical and on-going water supply and storage programs and management practices, the City will use up to the treated imported water supply made available from MWD through TVMWD in association with each of the standard water shortage levels identified in Section 3. Water demands will be addressed through increased use of the local groundwater supplies and implementation of demand reduction measures through the various stages of action.

The City has the flexibility to augment its existing water supplies through production of groundwater from the Six Basins and Chino Basin. The Six Basins is managed by the Six Basins Watermaster, and the Chino Basin is managed by the Chino Basin Watermaster.

During the periods of management under the Six Basin Judgment and the Chino Basin City of Pomona Page 23
2025 Water Shortage Contingency
Plan

Judgment, significant drought events have occurred. In each drought cycle, both the Six Basins and the Chino Basin have been managed to maintain water levels. Parties to the Six Basins Basin Judgment and Chino Basin Judgment, including the City, are authorized to produce groundwater in excess of their rights and pay assessments for such production to the respective Watermaster. The assessments are used to purchase untreated imported water to replenish the Six Basins and Chino Basin. The Six Basins Watermaster purchases untreated imported water to replenish the Six Basins from MWD through TVMWD. The Chino Basin Watermaster purchases untreated imported water to replenish the Chino Basin from MWD through Inland Empire Utilities Agency ( IEUA). In addition, groundwater quality in the Six Basins and the Chino Basin is not expected to impact potable supplies or constrain supply reliability. Groundwater quality is carefully monitored and managed by the Watermaster for each respective basin. In addition, Treatment facilities and/or blend plans have been developed by water agencies to meet potable water standards and to prevent the spread of any groundwater contamination. Based on historical and on-going management practices, the City will be able to continue relying on the Six Basins and Chino Basin for adequate supplies in response to each of the standard water shortage levels identified in Section 3. An additional potential source of replenishment water is recycled water.

Table 3. Supply Augmentation and Other Actions

Submittal Table 8-2: Supply Augmentation and Other Actions Shortage Level Supply Augmentation Methods and
Other Actions by Water Supplier
Drop down list
These are the only categories that will be
accepted by the WUEdata online submittal tool
How much is this going to reduce
the shortage gap? Include units
used (volume type or percentage)
Additional Explanation or Reference
(optional)
1 Transfers Not applicable (see Notes)
2 Transfers Not applicable (see Notes)
3 Transfers Not applicable (see Notes)
4 Transfers Not applicable (see Notes)
5 Transfers Not applicable (see Notes)
6 Transfers Not applicable (see Notes)
NOTES: The City will consider increased production from Six Basins and the Chino Basin using existing facilities to address increased demands. As noted on Table 2, the City plans to implement demand reduction measures in the event water supplies from existing sources are not sufficient to meet anticipated demands.

City of Pomona Page 24
2025 Water Shortage Contingency
Plan

4.3 OPERATIONAL CHANGES

During a water supply shortage situation, the City will manage its water supply resources to provide sufficient water supplies capable of meeting the demands of its customers.

Section 4.2 describes the City’s water supply sources and water supply augmentation actions available. Section 4.2 describes the City’s standard water shortage levels and associated demand reduction measures. The supply augmentation actions and demand reduction measures, when implemented, may potentially result in short -term operational changes which are necessary to allow the City to utilize all available water supply sources in response to water shortage situations.

As noted in Section 2, beginning July 1, 2022, the City has prepared and submitted an Annual Assessment which includes a review of the water supplies available to meet water demands for the current and upcoming years. Preparation of the Annual Assessment assists the City in determining any potential operational changes. In addition, the City’s standard water shortage levels and the associated demand reduction measures, in conjunction with the City’s existing Demand Management Measures (DMM) (discussed in Chapter 8 of the UWMP), will be essential to the City in reducing water demands during any water shortage period. The operational changes the City will consider in addressing non-catastrophic water shortages on a short-term basis include the following:
• Improved monitoring, analysis, and tracking of customer water usage to enforce demand reduction measures.
• Optimized production from existing available water supply sources. • Potential use of emergency supply sources, including emergency interconnections.
• Potential blending of water supply resources.
• Improved monitoring, maintenance, and repairs to reduce water distribution system losses.

4.4 ADDITIONAL MANDATORY RESTRICTIONS

City of Pomona Page 25
2025 Water Shortage Contingency
Plan

The mandatory restrictions which are implemented by the City to reduce customer demands are discussed in Section 4.2. There are no additional mandatory restrictions planned at this time.

4.5 EMERGENCY RESPONSE PLAN

Catastrophic water shortages are incorporated in the City’s standard water shortage levels (identified in Section 3) and the associated demand reduction measures (described in Section 4.1). In addition to the water supply augmentation actions (Section 4.2) and potential operational changes (Section 4.3) which the City may consider in order to continue providing sufficient water supplies, the City will review and implement any necessary steps included in its ERP.

As part of the “America’s Water Infrastructure Act of 2018”, community water systems serving a population greater than 3,300 people, including the City, are required to review and update their “Risk and Resilience Assessment” (RRA) and the associated ERP every five (5) years. However, due to security concerns regarding the submitting of these reports, water systems are required to submit certifications to the United States Environment Protection Agency (USEPA), confirming the current RRA and ERP have been reviewed and updated. For the City, the RRA certification was due by March 31, 2025, and the ERP certification was due by September 30, 2025.

The City’s RRA evaluates the vulnerabilities, threats, and consequences from potential hazards to the City’s water system. The City prepared its RRA (which is incorporated by reference) by evaluating the following items:

• Natural hazards and malevolent acts (i.e., all hazards); • Resilience of water facility infrastructure (including pipes, physical barriers, water sources and collection, treatment, storage and distribution facilities, and electronic, computer and other automated systems);
• Monitoring practices;
• Financial systems (e.g., billing systems);
• Chemical storage and handling; and
City of Pomona Page 26
2025 Water Shortage Contingency
Plan

• Operation and maintenance.

The City’s RRA evaluated a series of potential malevolent acts, natural hazards, and other threats in order to estimate the potential “monetized risks” (i.e. associated economic consequences to both the water system and surrounding region, and the likelihood of occurrence) associated with the City’s water facility assets. The cost -effectiveness of implementing potential countermeasures to reduce risks was also reviewed.

The City’s ERP provides the management, procedures, and designated actions the City and its employees will implement during emergency situations (including catastrophic water shortages) resulting from natural disasters, system failures, and other unforeseen circumstances. The City’s ERP (which is incorporated by reference) provides guidelines for evaluating an emergency situation, procedures for activating an emergency response, and details of the different response phases in order to ensure that customers receive a reliable and adequate supply of potable water. The scope of the ERP includes emergencies which directly affect the water system and the ability to maintain safe operations (such as chlorine release, and earthquake, or a threat of contamination). The ERP also incorporates the results of the City’s RRA and includes the following:

• Strategies and resources to improve resilience, including physical and cybersecurity;
• Plans and procedures for responding to a natural hazard or malevolent act; • Actions and equipment to lessen the impact of a natural hazard or malevolent act; and
• Strategies to detect natural hazards or malevolent act.

The City will review the ERP for procedures regarding the utilization of alternative water supply sources in response to water supply shortages, including during the standard water shortage levels. The City will also review applicable procedures described in the ERP regarding any necessary temporary shutdown of water supply facilities, including appropriate regulatory and public notifications.

City of Pomona Page 27
2025 Water Shortage Contingency
Plan

4.6 SEISMIC RISK ASSESSMENT AND MITIGATION PLAN

CWC 10632.5.

(a) In addition to the requirements of paragraph (3) of subdivision (a) of Section 10632, beginning January 1, 2020, the plan shall include a seismic risk assessment and mitigation plan to assess the vulnerability of each of the various facilities of a water system and mitigate those vulnerabilities.

(b) An urban water supplier shall update the seismic risk assessment and mitigation plan when updating its urban water management plan as required by Section 10621.

(c) An urban water supplier may comply with this section by submitting, pursuant to Section 10644, a copy of the most recent adopted local hazard mitigation plan or multihazard mitigation plan under the federal Disaster Mitigation Act of 2000 (Public Law 106 -390) if the local hazard mitigation plan or multihazard mitigation plan addresses seismic risk.

The City prepared a local “Natural Hazards Mitigation Plan Update” which was approved by the Federal Emergency Management Agency (FEMA) in 20 22. The “Natural Hazards Mitigation Plan Update” identifies effective ways to assess the significant natural hazards (including earthquakes) that may affect the City and its residents. The “Natural Hazards Mitigation Plan Update” provides resources, information, and strategies to reduce the City’s vulnerability to these hazards, while providing guidance for the c oordination of mitigation activities throughout the City. The “Natural Hazards Mitigation Plan Update” includes mitigation projects necessary to reduce seismic risk to the City’s water distribution system facilities (including its distribution system pipelines, groundwater wells, booster pumps, and storage reservoirs) and potential disruptions in providing water service. The City’s “Natural Hazards Mitigation Plan Update” is provided in Appendix B.

The County of Los Angeles prepared an “All-Hazards Mitigation Plan” in 20 25 which identified methods to assess significant natural hazards (including earthquakes) affecting areas throughout Los Angeles County, and the mitigation strategies necessary to reduce risks, including seismic risk. The County’s All -Hazards Mitigation Plan is provided in Appendix C.

The California Geological Survey has published the locations of numerous faults which have been mapped in the Southern California region. Although the San Andreas fault is the most recognized and is capable of producing an earthquake with a magnitude greater City of Pomona Page 28
2025 Water Shortage Contingency
Plan

than 8 on the Richter scale, some of the lesser -known faults have the potential to cause significant damage. The locations of these earthquake faults in the vicinity of the City’s water service area are provided in the figure below. The faults that are located in close proximity to and could potentially cause significant shaking in the City’s water service area include the San Andreas fault, the Whittier fault, the San Jose fault, the Chino fault, the Central Avenue fault, and the Sierra Madre fault.

Location of Earthquake Faults
Source: https://maps.conservation.ca.gov/cgs/fam/App/

The following figure provides the relative intensity of ground shaking in the vicinity of the City’s service area from anticipated future earthquakes. The locations of relatively long - period (1.0 second) earthquake shaking, including the City’s service ar ea, are provided.

Long-period shaking affects tall, relatively flexible buildings, but also correlates with earthquake damage. The shaking potential is calculated based on the level of ground motion that has a 2 percent chance of being exceeded in 50 years (or the level of ground- shaking with an approximate 2,500 -year average repeat time). As discussed in Section

4.5, the City has prepared an ERP which provides the management, procedures, and designated actions the City and its employees will implement during emergency situations resulting from natural disasters, including during earthquakes, to ensure that customers

City of Pomona Page 29
2025 Water Shortage Contingency
Plan

receive a reliable and adequate supply of potable water. The City’s ERP is incorporated by reference.

Earthquake Shaking Potential

Source: “Earthquake Shaking Potential for California”, 2016, California Geological Survey and United States Geological Survey

4.7 SHORTAGE RESPONSE ACTION EFFECTIVENESS

The effectiveness of the shortage response actions for each of the standard water shortage levels identified in Section 3 is evident in the City’s historical ability to meet its customer’s water demands in response to a water supply shortage. In addition, the City imposes water consumption regulations and restrictions and supports local agencies in efforts to enforce regulations and prohibitions on water use. The effectiveness of each of the City’s shortage response actions, in order to reduce any potential gaps between supply and demand, has been quantified in the expected demand reduction provided in Table 2 and Table 3.

During the past five years, the City experienced a consecutive two-year drought within its service area from FY 2021 to FY 2022 . Throughout this extended dry year period, the City’s Service Area
City of Pomona Page 30
2025 Water Shortage Contingency
Plan

City’s annual water production averaged 21,505 acre-feet per year (AFY). During the past five years, the average annual production was approximately 19,881 AFY, with a maximum of up to 22,029 AF during FY 2021. The City has been able to provide sufficient water supplies to its customers, including during long-term droughts and years with historically high water demands. In addition, the City has been able to provide water service to meet maximum day water demands for these years, including during the summer months.

The City’s water demands during the most recent five years averaged approximately 17,168 AFY of potable water . Due to conservation efforts and demand management measures (discussed in Chapter 8 of the UWMP), the City’s recent water demands have been less than its historical water demands, including during long -term droughts. The City’s projected water demands (during a normal year, a single dry year, and a five consecutive year drought conditions) are provided in Section 5.3 of the UWMP and are anticipated to incorporate similar reductions in water use rates as a result of the shortage response actions, ongoing conservation efforts, and demand management measures. It is anticipated the City will be able to continue providing sufficient water supplies to its customers to meet projected water demands, including during long -term droughts. In addition, as discussed in Section 4.2, based on historical and on -going managem ent practices, the City will be able to continue relying on its water supply sources from the Chino Basin, Spadra Basin, and Six Basins for adequate supply augmentation in response to each of the standard water shortage levels identified in Section 3.

The City previously adopted Resolution No. 2015-41 in May 2015 which declared a water supply shortage and established water-use restrictions and regulations equivalent to the standard water shortage level 2 identified in Section 3. During this Level 2 water shortage period, the City was able to reduce water demands by up to 20 percent and provide sufficient water supplies to its customers. Subsequently, the City adopted Resolution No. 2016-105 in July 2016 which rescinded the Level 2 water supply shortage and declared a water supply shortage equivalent to standard water shortage Level 1. During this Level 1 water shortage period, the City was able to reduce water demand by up to 10 percent and City of Pomona Page 31
2025 Water Shortage Contingency
Plan

provide sufficient water supplies to its customers. Copies of the resolutions are provided in Appendix A.

Based on the City’s demonstrated ability to meet water demands during past water supply shortages, the adopted water shortage levels, the adjusted operating safe yields, and water supplies through long -term droughts, it is anticipated that the City will be able to provide sufficient water supplies to its customers during each of its st andard water shortage levels. Although adequate supplies are anticipated, the cost of those water supplies may become incrementally more expensive. The City will enact varying levels of its WSCP to encourage retail customers to reduce water consumption and at the same time reduce the need to use the more expensive water supplies. Notwithstanding, the effectiveness of each of the City’s shortage response actions, in order to reduce any potential gaps between supply and demand, has been quantified in the expected demand reduction section provided in Table 2 and Table 3. The effectiveness of the City’s shortage response actions are based on the City’s water demands prior to 2015 (unconstrained demands). The City reduced its water demands in 2015 in response to the Governor’s April 1, 2015, Executive Order B -29-15 which mandated statewide reduction in water use of 25 percent. The City’s actual water demand reduction during this period was used to estimate the extent of water use reductions for the City’s Water Shortage Stages. The City’s Water Shortage Levels 1, 2, 3, 4, 5, and 6 are expected to reduce water demands by up to 10%, 20%, 30%, 40%, 50%, and greater than 50%, respectively.

5 COMMUNICATION PROTOCOLS

CWC 10632.

(a)(5) Communication protocols and procedures to inform customers, the public, interested parties, and local, regional, and state governments, regarding, at a minimum, all of the following:

(A) Any current or predicted shortages as determined by the annual water supply and demand assessment described pursuant to Section 10632.1.

(B) Any shortage response actions triggered or anticipated to be triggered by the annual water supply and demand assessment described pursuant to Section 10632.1.

(C) Any other relevant communications.

City of Pomona Page 32
2025 Water Shortage Contingency
Plan

The City utilizes established communication protocols and procedures to inform customers, the general public, interested parties, and local agencies of current or anticipated water shortages, shortage response actions, and other relevant information.

Beginning July 1, 2022, the City has submitted an Annual Assessment in accordance with DWR’s guidance and requirements. The Annual Assessment include s a review of the City’s unconstrained water demands (i.e. water demands prior to any projected response actions the City may trigger under this WSCP) for the current year and the upcoming (potential single dry) year. The City will also include information regarding anticipated shortages, triggered shortage response actions, compliance and enforcement actions, and communication actions consistent with the City’s WSCP. See Section 2 for more information regarding the Annual Assessment.

Standard water shortage levels may be declared by resolution of the City Council, adopted at a regular or special public meeting held in accordance with state law. The mandatory conservation requirements applicable to the shortage level conditions will take effect on the 10th day after the date the shortage level is declared. Within seven days following the declaration of the shortage level, the City must publish a copy of the resolution in a newspaper used for publication of official notices. If the City establishes a water allocation, it must provide notice of the allocation by including it in the regular billing statement. A water allocation will be effective on the 5th day following the date of mailing or at such later date as specified in the notice. The City may declare an end to any water shortage level upon recommendation by the City Manager, or designee, and resolution by the City Council at any regular or special meeting of the City Council.

Under unique circumstances where a specific requirement of this WSCP would result in undue hardship to a customer that is disproportionate to the impacts on other customers, the customer may apply for a waiver pursuant to the requirements as provided in this WSCP. The waiver may be granted or conditionally granted only upon a written finding of the existence of facts demonstrating an undue hardship to the customer. The customer must provide the following documents for review:

City of Pomona Page 33
2025 Water Shortage Contingency
Plan

(1) The application for a waiver prescribed by the City and accompanied by a non - refundable processing fee in an amount set by City Council resolution. (2) Photographs, maps, drawings, and other information, including a written statement of the applicant.

An application for a waiver will be denied unless the City finds, based on the information provided in the application, supporting documents, or such additional information that may be requested, and on water use information for the property as shown by the records of the City or its agent, all of the following:

(1) That the waiver does not constitute a grant of special privilege inconsistent with the limitations upon other customers;
(2) That, because of special circumstances applicable to the property or its use, the strict application of this division would have a disproportionate impact on the property or use that exceeds the impacts to residents and businesses generally; (3) That the authorizing of such waiver will not be of substantial detriment to adjacent properties, and will not materially affect the ability of the City to effectuate the purpose of this division and will not be detrimental to the public interest; and (4) That the condition or situation of the subject property or the intended use of the property for which the waiver is sought is not common, recurrent, or general in nature.

The City Manager or designee must act upon any completed application no later than ten business days after submittal and may approve, conditionally approve, or deny the waiver.

The applicant requesting the waiver must be promptly notified in writing of any action taken. Unless specified otherwise at the time a waiver is approved, the wai ver will apply to the subject property during the period of the mandatory water supply shortage condition. The decision of the City Manager, or designee, shall be final.

City of Pomona Page 34
2025 Water Shortage Contingency
Plan

6 COMPLIANCE AND ENFORCEMENT

CWC 10632.

(a)(6) For an urban retail water supplier, customer compliance, enforcement, appeal, and exemption procedures for triggered shortage response actions as determined pursuant to Section 10632.2.

Any violation of this WSCP is considered a waste and an unreasonable use of water. The City will track violations by analyzing the City water loss audits for potential leak locations and by documenting correspondence of the City Water Watcher Reporting Line, a 24- Hour Service where customers can report witnessing the abuse of water supplies.

Any violation of this WSCP may be prosecuted as a misdemeanor or as an infraction, at the discretion of the City, pursuant to Article X of the Pomona Municipal Code (Code).

Pursuant to Section 1 -7 of this Code, a misdemeanor is punishable by imprisonment i n the county jail for no more than 30 days, or by a fine not exceeding $1,000.00, or by both.

The City Manager and respective departments shall have the authority to administer and enforce this division.

Pursuant to this WSCP, penalties for failure to comply with any provisions of the WSCP are as follows:
(1) A fine not exceeding $100.00 for a first violation.

(2) A fine not exceeding $200.00 for a second violation of the same provision within one year.
(3) A fine not exceeding $500.00 for each additional violation of the same provision within one year.
a. Water flow restrictor: In addition to any fines, the City may install a water flow restrictor device of approximately one gallon per minute capacity for services up to one and one-half inch size and comparatively sized restrictors for larger services after written notice of inte nt to install a flow restrictor for a minimum of 48 hours.

City of Pomona Page 35
2025 Water Shortage Contingency
Plan

b. Termination of service: In addition to any fines and the installation of a water flow restrictor, the City may disconnect and/or terminate a customer's water service.

A person or entity that violates this division is responsible for payment of the City's charges for installing and/or removing any flow restricting device and for disconnecting and/or reconnecting service per the City's schedule of charges then in effect. The charge for installing and/or removing any flow restricting device must be paid to the City before the device is removed. Nonpayment will be subject to the same remedies as nonpayment of basic water rates.

Pursuant to this WSCP, each day that a violation of this ordinance occurs is a separate offense.

The City will issue a notice of violation by mail or personal delivery at least ten days before taking enforcement action. Such notice must describe the violation and the date by which corrective action must be taken. A customer may appeal the violation by filing a written notice of appeal pursuant to this WSCP.

Pending receipt of a written appeal or pending a hearing pursuant to an appeal, the City may take appropriate steps to prevent the unauthorized use of water as appropriate to the nature and extent of the violations and the current declared water shortage level condition.
7 LEGAL AUTHORITIES

CWC 10632.

(a)(7)(A) A description of the legal authorities that empower the urban water supplier to implement and enforce its shortage response actions specified in paragraph (4) that may include, but are not limited to, statutory authorities, ordinances, resolutions, and contract provisions.

(B) A statement that an urban water supplier shall declare a water shortage emergency in accordance with Chapter 3 (commencing with Section 350) of Division 1.

(C) A statement that an urban water supplier shall coordinate with any city or county within which it provides water supply services for the possible proclamation of a local emergency, as defined in Section 8558 of the Government Code.

City of Pomona Page 36
2025 Water Shortage Contingency
Plan

CWC Division 1, Section 350

The governing body of a distributor of a public water supply, whether publicly or privately owned and including a mutual water company, shall declare a water shortage emergency condition to prevail within the area served by such distributor whenever it finds and determines that the ordinary demands and requirements of water consumers cannot be satisfied without depleting the water supply of the distributor to the extent that there would be insufficient water for human consumption, sanitation, and fire protection.

The City is responsible for implementing and enforcing the water shortage response actions described in Section 4. This WSCP is subject to any changes deemed necessary by the City.

The City Manager, or designee, may declare a water shortage emergency and may immediately enact the mandatory requirements of any of the levels designated herein.

The required measures of the designated water shortage level will be effective immediately and will be communicated to the public. The emergency implementation will be ratified by resolution of the City Council at its next meeting.

The City shall coordinate with any city or county within which it provides water supply services for the possible proclamation of a local emergency. This includes the Cities of Chino Hills, Claremont, La Verne, and Montclair, and the County of Los Angeles.

The City shall declare a water shortage emergency in accordance with CA Water Code CHAPTER 3 - Water Shortage Emergencies § 350 – 358. Legal authorities include California Water Code Sections 71640 -71644 Article 3. Water Shortages and CA Water Code § 366 (2025) CHAPTER 3.3 - Excessive Residential Water Use During Drought. 8 FINANCIAL CONSEQUENCES OF WSCP

CWC 10632.

(a)(8) A description of the financial consequences of, and responses for, drought conditions, including, but not limited to, all of the following:

(A) A description of potential revenue reductions and expense increases associated with activated shortage response actions described in paragraph (4).

(B) A description of mitigation actions needed to address revenue reductions and expense increases associated with activated shortage response actions described in paragraph (4).

City of Pomona Page 37
2025 Water Shortage Contingency
Plan

(C) A description of the cost of compliance with Chapter 3.3 (commencing with Section 365) of Division 1.

To ensure compliance with CWC Chapter 3.3 (commencing with Section 365), additional costs may be incurred to monitor and enforce WSCP actions. These costs may vary depending on the applicable water shortage stage and the duration of the water shortage emergency.

The City’s primary source of revenue is user service charges, which consists of bimonthly fixed readiness-to-serve charges according to meter size and a volumetric charge per unit of water consumed. The bimonthly fixed readiness-to-serve charges are sufficient to meet about 45 percent of the City’s operations and maintenance expenses. The revenue from the consumption charge is designed to be sufficient to fund the remaining 55 percent of the operations and maintenance expenses plus all of the variable expenses associated with the cost of water. The current water rates are provided in Appendix D.

The City Council may adopt resolutions to make additional adjustments to the water rates based on the City’s increased costs to provide water for its customers.

The City has historically maintained a financial reserve in its Water Fund. The City may use financial reserves for water system expenditures to make up for shortfalls in water revenue associated with unanticipated reduced water sales. 9 MONITORING AND REPORTING

CWC 10632.

(a)(9) For an urban retail water supplier, monitoring and reporting requirements and procedures that ensure appropriate data is collected, tracked, and analyzed for purposes of monitoring customer compliance and to meet state reporting requirements.

Customer compliance with the provisions adopted by declaration of a WSCP are monitored and reported through water loss audits performed by the City’s Water Resource Department. Staff prepare annual Distribution System Water Audits to monitor water City of Pomona Page 38
2025 Water Shortage Contingency
Plan

losses. Staff review the audits to track real and apparent losses. Losses are monitored by comparing water production to sales. The City regularly monitors its system and repairs leaks in a timely manner. To help in its effort to reduce and eliminate losses, the City has purchased various sound correlators for identifying system leaks. In those areas where a leak is visible, staff are dispatched to a site to pinpoint the leak to minimize the excavation area and save resources.

The City’s Water Resources Department is also the first point of contact of the City Water Watcher Reporting Line, a 24-Hour Service where customers can report witness of abuse of water supplies. Reports are documented for record of offenses and necessary penalties.
10 WSCP REFINEMENT PROCEDURES

CWC 10632.

(a)(10) Reevaluation and improvement procedures for systematically monitoring and evaluating the functionality of the water shortage contingency plan in order to ensure shortage risk tolerance is adequate and appropriate water shortage mitigation strategie s are implemented as needed.

The City’s WSCP has been prepared as an adaptive management plan. As discussed in Section 9, the City will monitor and report on the implementation of the WSCP. The City will review the implementation results for any current or potential shortage gaps between water supplies and demands. The City will evaluate the need for revising the WSCP in order to resolve any shortage gaps, as necessary. The City will consider the following potential revisions in the event of a potential shortage gap:
• Implementation of additional public outreach, education, and communication programs (in addition to the programs discussed in Chapter 8 of the UWMP). • Implementation of more stringent water use restrictions under the standard water shortage levels (discussed in Section 4.2).
• Implementation of stricter enforcement actions and penalties (discussed in Section 6).

City of Pomona Page 39
2025 Water Shortage Contingency
Plan

• Improvements to the water supply augmentation responses (discussed in Section

4.2), as well as any associated operational changes (discussed in Section 4.3) which may be required.
• Incorporation of additional actions recommended by City staff or other interested parties.

The City will use the monitoring and reporting data to evaluate the ability for these potential revisions to resolve any shortage gaps which may occur within the standard water shortage levels.

This WSCP is adopted as part of the City’s 202 5 UWMP adoption process discussed in Section 9.2 of the UWMP . It is anticipated the City will review, revise, and adopt an updated WSCP as part of preparing its 20 31 UWMP, as necessary. However, the City will continue to review the monitoring and reporting data, and if needed, update the WSCP more frequently. Any updates to the City’s WSCP will include a public hearing and adoption process by City Council (see Section 12).

11 SPECIAL WATER FEATURE DISTINCTION
__

CWC 10632.

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

The City’s WSCP defines “decorative water features” as water features which are artificially supplied with water, including ponds, lakes, waterfalls, and fountains, but excluding pools and spas. In general, there are additional health and safety considerations in the water supplied to pools and spas compared to decorative water features. As a result, the City’s WSCP has reviewed the response actions, enforcement actions, and monitoring and reporting programs separately for decorative water features and for pools and spas, as applicable.

City of Pomona Page 40
2025 Water Shortage Contingency
Plan

Please see Section 4.1. for specific demand reduction actions in relation to special water features.
12 PLAN ADOPTION, SUBMITTAL, AND AVAILABILITY
__

CWC 10632.

(c) The urban water supplier shall make available the water shortage contingency plan prepared pursuant to this article to its customers and any city or county within which it provides water supplies no later than 30 days after adoption of the water shortage contingency plan.

CWC 10635.

(c) Provide supporting documentation that Water Shortage Contingency Plan has been, or will be, provided to any city or county within which it provides water, no later than 30 days after the submission of the plan to DWR.

The City’s WSCP is adopted as part of the City’s 202 5 UWMP adoption process discussed in Chapter 9 of the UWMP. The process for adopting the City’s WSCP includes the following:
• The City will conduct a public hearing and make the WSCP available for public inspection.
• The City will provide notification of the time and place of the public hearing to any city or county in which water is provided.
• The City will publish notice of public hearing in a newspaper once a week, for two successive weeks (with at least five days between publication dates). • The City Council will adopt the 2025 UWMP and the WSCP. • As part of submitting the 2025 UWMP to DWR, the City will also submit the WSCP (electronically through DWR’s online submittal tool) within 30 days of adoption and by July 1, 202 6. The City will submit a copy of the WSCP to the California State Library and to any city or county in which water is provided within 30 days of adoption. In addition, the City will make the WSCP available for public review within 30 days of adoption.

If there are any subsequent amendments required, the process for adopting an amended WSCP includes the following:

City of Pomona Page 41
2025 Water Shortage Contingency
Plan

The City will conduct a public hearing and make the amended WSCP available for public inspection.
• The City Council will adopt the amended WSCP.
• The City will submit the amended WSCP to DWR (electronically through DWR’s online submittal tool) within 30 days of adoption.
• Within 30 days after submission of the WSCP to DWR, the City will provide the WSCP to any city or county within which the City provides water.

Additional information regarding the adoption, submittal, and availability of the City’s WSCP (and 2025 UWMP) is provided in Chapter 9 of the UWMP.

APPENDIX A

CITY OF POMONA ORDINANCE AND RESOLUTIONS

RESOLUTION NO. 2015- 41

A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF POMONA, CALIFORNIA, DECLARING A LEVEL 2 WATER SUPPLY SHORTAGE
AND IMPLEMENTING LEVEL 2 RESTRICTIONS FOR WATER USE

REDUCTION TO OUTDOOR URBAN WATER USE
WHEREAS, at the June 15, 2009 City Council meeting, the City Council adopted Ordinance No. 4122 a " Water Conservation and Water Supply Shortage Program" (" Water ConservationProgram") that becameeffective immediatelyupon adoptionpursuantto Water Code Section 376;
WHEREAS, the Water Conservation Program allows the City Council to declareby Resolution a water supply shortage level, and statesthat the conservation requirements shall take effect on the l0a' day after the water shortage level is declared; WHEREAS, on January 17, 2014, Governor Edmund G. Brown Jr. issued a Drought Emergency Proclamation (January 2014 Proclamation) due to the dire drought conditions and the need to conserve more;
WHEREAS, on February 24, 2014, the City Council adopted a Resolution to request a voluntary water use reduction by all City water customers in responseto Governor Brown' s Drought Declaration and Metropolitan Water District' s ( MWD) Statement regarding California' s Water Supply Shortage;
WHEREAS, Water Code Section 1058.5 grants the State Water Resources Control Board (SWRCB) the authority to adopt emergencyregulations in certain drought years to:

Prevent the waste, unreasonable use, unreasonable method of use, or unreasonable method of diversion, of water, to promotewaterrecyclingor waterconservation, to requirecurtailmentof diversionswhenwateris not availableunderthe diverter'spriority of right, or in furtheranceof anyof the foregoing, to requirereportingof diversionor useor the preparationof monitoringreports".

WHEREAS, On July 15, 2014, SWRCB adoptedan emergencyregulation to support water conservation (Resolution No. 2014-0038) andthat regulation becameeffective July 28, 2014 after approval by the Office of Administrative Law( OAL).

WHEREAS, On March 17, 2015, the SWRCB adopted a Resolution to implement an ExpandedEmergencyWater Conservationrequirementdue to the continuing emergency droughtconditions (ExecutiveOrderB-29-15)to safeguardtheState'sremainingwatersupply.

WHEREAS, on May 5, 2015, the SWRCBhasadopteda RegulatoryFrameworkto outline the Governor's ExecutiveOrder and mandatoryactionsthat needto be takenby water suppliers.

Resolution No. 2015- 41
May 18, 2015