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IRVINE RANCH WATER DISTRICT
2025 URBAN WATER MANAGEMENT PLAN
JUNE 2026 DRAFT
2025 Urban Water Management Plan Contact Sheet
Date Submitted to Department of Water Resources DATE HERE
Person Responsible for this Plan Fiona Nye, Director of Water Resources Phone (949) 453 - 5325 Email Address nye@irwd.com Water Supplier is a Special District
Water Supplier Type (Retailer or Wholesaler) Retailer
Utility Services Provided Water | Sewer | Recycled Water
Is this agency a Bureau of Reclamation Contractor? No Is this agency a State Water Project Contractor? No
Main Office: 15600 Sand Canyon Avenue Irvine, California 92618
Acronyms and Definitions
AF acre-feet AFY acre-feet per year cfs cubic feet per second FY fiscal year in inches ksf thousand square feet kWh kilowatt hour gpd/acre gallons per acre per day mgd million gallons per day
AMP
Allen-McColloch Pipeline
AWIA
America's Water Infrastructure Act of 2018
AWWA
American Water Works Association
AWSDA
Annual Water Supply and Demand Assessment
Baker / BWTP
Baker Water Treatment Plant
Basin / Basin 8 -1
Coastal Plain of Orange County Groundwater Basin
Basin 8-1 Alternative A local alternative collaboration to meet SGMA GSP compliance
BDCP
Bay-Delta Conservation Plan
BEA
Basin Equity Assessment
Board
IRWD Board of Directors
BPP
Basin Production Percentage
CAC
California Administrative Code
CalWEP
California Water Efficiency Partnership
CDR
Center for Demographic Research at California State Fullerton
CECs
Constituents of Emerging Concern / Chemicals of Emerging Concern
CEQA
California Environmental Quality Act
i
Acronyms and Definitions
CII
Commercial, Industrial, and Institutional
CIMIS
California Irrigation Management Information System
COA
Coordinated Operating, Water Storage, Exchange, and Delivery Agreement between IRWD, MWD, and MWDOC
CRA
Colorado River Aqueduct
CSL
Coastal Supply Line
CVAP
Citizen Voting Age Population
CVP
Central Valley Project
DATS
Deep Aquifer Treatment System
DDW
California State Division of Drinking Water
Delta / Bay-Delta
San Francisco Bay/Sacramento-San Joaquin Delta
Delta Reform Act / Delta Plan
Sacramento-San Joaquin Delta Reform Act of 2009
DFP
Metropolitan Diemer Filtration Plant
DMM
Demand Management Measures
DMRS
Delta Risk Management Strategy
DOF
Department of Finance
DRA
Drought Risk Assessment
DRWD
Dudley Ridge Water District
DRWF
Dyer Road Well Field
DVL
Diamond Valley Lake
DWR
California Department of Water Resources
EEP
Embedded Energy Plan (and subsequent updates)
EOCF #2
East Orange County Feeder No. 2
EPA
United States Environmental Protection Agency
ERP
Emergency Response Plan
ii
Acronyms and Definitions
ETo
Evapotranspiration
Evaluation
2016 IRWD Water Supply Reliability Evaluation
GAP
Green Acres Project
GHG
Greenhouse Gas
GIS
Geographic Information System
GM
General Manager
GPCD
Gallons per capita per day
GSA
Groundwater Sustainability Agencies
GSP
Groundwater Sustainability Plans
Guidebook
DWR Guidebook to Assist Urban Water Suppliers to Prepare a 2020 Urban Water Management Plan
GWRS
Groundwater Replenishment System
HOA
Homeowners Association
IDP
Irvine Desalter Plant / Irvine Desalter Project
ILP
Irvine Lake Pipeline
IPR
Indirect Potable Reuse
IRP
Integrated Resources Plan (as developed by Metropolitan for regional supplies)
IRPDSM
Integrated Resources Planning Distribution System Model
IRWD / District
Irvine Ranch Water District
KWB
Kern Water Bank
LAWRP
Los Alisos Water Recycling Plant
LHMP
Local Hazard Mitigation Plan
MCAS
Marine Corps Air Station
Metropolitan / MWD Metropolitan Water District of Southern California
MJHMP
Multi-Jurisdictional Hazard Mitigation Plan
iii
Acronyms and Definitions
MOU
Memorandum of Understanding
MWDOC
Municipal Water District of Orange County
MWRP
Michelson Water Recycling Plant (Owned and Operated by IRWD)
NAICS
North American Industry Classification System
NIDIS
National Integrated Drought Information System
OCF
Orange County Feeder
OCSD
Orange County Sanitation District
OCWD
Orange County Water District
OPA
Orange Park Acres
PFAS
per- and polyfluoroalkyl substances
PFOA
perfluorooctanoic acid, C8, a type of PFAS
RA
Replenishment Assessment
RIDM
Risk-Informed Decision-Making
Rosedale
Rosedale-Rio Bravo Water Storage District
RRA
Risk and Resilience Assessment
RRBWSD GSA
Rosedale-Rio Bravo Water Storage District Groundwater Sustainability Agency
SAC
Santiago Aqueduct Commission
SAMP's
Sub Area Master Plans
SB X7-7
Senate Bill X7-7, Water Conservation Act of 2009
SCADA
Supervisory Control and Data Acquisition
SCSMP
Sewer Collection System Master Plan
SGMA
Sustainable Groundwater Management Act of 2014
SMWD
Santa Margarita Water District
SOCWA
South Orange County Wastewater Authority
iv
Acronyms and Definitions
SWP
State Water Project
SWRCB
State Water Resources Control Board
TDS
Total Dissolved Solids
TIC
(The) Irvine Company
Title 22
California Administrative Code, Title 22, Division 4 - Standards Set for Recycled Water
UCI
University of California, Irvine
UWMP / Plan
Urban Water Management Plan
VOC
Volatile Organic Compounds
Water Bank
Strand Ranch Integrated Banking Project and the Stockdale Integrated Banking Project
Water Code / CWC
California Water Code
WDF
Water Demand Forecasting
WEROC
Water Emergency Response Organization of Orange County
WRMP
Water Resources Master Plan
WRP
IRWD Water Resources and Communications Board Committee
WSA
Water Supply Assessment
WSAP
Water Supply Allocation Plan - Metropolitan
WSAR
Water Shortage Assessment Report
WSCP
Water Shortage Contingency Plan
WSDA
Water Supply and Demand Assessment
WSDM
Water Surplus and Drought Management Plan - Metropolitan
WSRA
Water Supply Reliability Assessment
WTP
Water Treatment Plant
WUE
Water Use Efficiency
v
Acronyms and Definitions
Table of Contents
Executive Summary and Simple Lay Description of the UWMP Findings………………..……..ES-1 Urban Water Management Plan…………………………………………………………….ES-1 IRWD Water Service Reliability….…………………………………….……………………ES-1 Hydrologic Conditions and Reporting Period………………….………………………….ES-2 Findings of the 2020 UWMP…………………………….…………………………………..ES-2 Future Challenges and Strategies to Manage Reliability Risk………………………..….ES-3 Section 1 | Introduction…..…………………………………………………………………………….1-1 1.1 Urban Water Management Planning Act………………...………………………….1-1 1.2 Irvine Ranch Water District (IRWD)……...…………………………………………..1-1 1.3 Purpose and Importance: IRWD Water Resources Planning……………………..1-2 1.4 UWMP Organization and Section Summaries………………………………………1-2 Section 2 | Plan Preparation…...………………………………………………………………………2-1 2.1 Basis for Preparing a Plan……………………………………………………………2-1 2.2 Public Water Systems………..……………………………………………………….2-1 2.3 Regional Planning and Regional Alliance……………….…………………………..2-2 2.4 Standardized Tables, Year, and Units of Measurement……….………………….2-2 2.5 Coordination and Outreach…………………..………………………………………2-4 Coordination with Wholesale Agencies…………………………………………….2-4 Coordination with Water Suppliers and the Community…………………...……..2-5 Section 3 | System Description……………………………………………………………………….3-1 3.1 General Description……………..…………………………………………………….3-1 3.2 Service Area Boundaries……………………………………………………………..3-3 3.3 Population…………….………………………………………………………………..3-5 3.4 Local Climate……………………………….………………………………………….3-5 3.5 Historic, Current and Projected Land Use…………………………………….……3-6 Land Use Major Changes Over Time………………………….……………………3-6 Land Use and Water Resource Planning…………………………...………………3-7
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IRWD – 2025 Urban Water Management Plan – Table of Contents
Table of Contents
3.6 Other Demographic and Socioeconomic Factors…………………………………3-9 Section 4 | Customer Water Use………………………..…………………………………………….4-1 4.1 Description of Defined Water Use Sectors……………………………..…………..4-2 4.2 Past, Current, and Projected Water Use by Sector………..………………………4-3 Estimating Future Water Savings……………………………………………………4-5 Water Use of Lower Income Households…………………………………..……….4-6 Climate Change Considerations on Customer Water Use……………….……….4-6 4.3 Distribution Water System Losses……………….………………………………….4-7 Section 5 | SBX7-7 Baselines and Targets…………………………………………………………..5-1 5.1 2020 Water Conservation Mandate…………………………...…………………….5-1 5.2 Regional Alliance………………………………………...……………………………5-2 Section 6 | System Supplies…………………………….…………………………………………….6-1 6.1 Purchased or Imported Water……………………………………………………….6-2 Imported Potable Water……………………………..………………………………..6-2 Imported Non-Potable Water………………….……………………………………..6-2 6.2 Groundwater…..………………………………………………….……………………6-3 Basin Description……………..………………………………….……………………6-3 IRWD Groundwater Production…………………………….………………………..6-4 Groundwater Sustainability Plan for the Orange County Basin……………..……6-6 OCWD Basin Management……….………………………………………………….6-8 6.3 Surface Water…………………………………..……………………………………..6-8 Irvine Lake……………………………………………………………………………..6-8 6.4 Stormwater……………………….……………………………………………………6-9 6.5 Wastewater and Recycled Water……………………………………..……………..6-9 Sewage Collection, Treatment, and Disposal…………………………………….6-10 Recycled Water Direct Beneficial Uses……………………………………………6-13 Current and Projected Use of Recycled Water………………………….………..6-14 Optimizing Future Recycled Water Use – Recycled Water Projects…...………6-14
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IRWD – 2025 Urban Water Management Plan – Table of Contents
Table of Contents
6.6 Desalinated Water and Opportunities..…………………………...……………….6-17 6.7 Transfers and Exchanges……………...……………………………………………6-18 6.8 Supply From Storage…………………………………………………………….….6-19 6.9 Other………………………………………………………………………………….6-19 6.10 Future Water Projects and Supplies……………………………………………….6-19 6.11 Water Portfolio Summary: Existing and Planned Sources………………………6-21 Existing Sources……………………………………………………………………..6-21 Planned Sources…………………………………………………………………….6-22 6.12 Energy Intensity……………………………………………………………………….6-23 Section 7 | Water Supply Reliability and Drought Risk Assessment………………………………7-1 7.1 Constraints on Water Sources Considerations…………………………………….7-1 A. Recent IRWD Water Reliability Studies and Evaluations……………………….7-2 B. Historic Drought Analysis…………………………………………………………7-4 C. Water Supply Reliability Projections……………………………………………..7-4 7.2 Water Service Reliability Assessment………………………………………………7-8 A. Imported Water…………………………………………………………………….7-8 B. Groundwater Supply………………………………………………………………7-8 C. Non-Potable Water Management………………………………………………...7-9 D. Climate Change Considerations………………………………………………….7-9 E. Reduced Reliance on the Delta…………………………………………………7-10 7.3 Water Quality…………………………………………………………………………7-10 Groundwater Quality………………………………………………………………...7-11 Other Water Quality Considerations……………………………………………….7-11 Imported Water Quality……………………………………………………………..7-12 7.4 Drought Risk Assessment…………………………………………………………..7-12 Drought Risk Assessment Data Inputs and Methods…………………………….7-13 Drought Risk Assessment Data Inputs and Methods…………………………….7-15
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IRWD – 2025 Urban Water Management Plan – Table of Contents
Table of Contents
Section 8 | Water Shortage Contingency Plan………………………………………………………8-1 8.1 Overview of Water Shortage Contingency Plan…………………………………...8-1 8.2 Summary of Sections and Requirements…………………………………………..8-2 8.3 Copy of DWR Tables………………………………………………………………….8-3 8.4 Plan Adoption, Submittal, and Availability…………………………………………..8-8 Section 9 | Demand Management Measures………………………………………………………. 9-1 9.1 Demand Management Measure Implementation…………………………………..9-1 A. Budget-Based Rate Structure…………………………………………………….9-2 B. Revenue Stability…………………………………………………………………..9-2 C. Price Signal to Reduce Water Waste…………………………………………….9-3 D. Rate Structure Results…………………………………………………………….9-3 9.2 Water Use Efficiency Programs and Resources…………………………………...9-4 A. Programs……………………………………………………………………………9-4 B. Workshops and Tours……………………………………………………………..9-5 C. Public Outreach and Social Media………………………………………………9-5 D. Education Programs……………………………………………………………….9-5 E. Water Waste Prevention…………………………………………………………...9-6 F. Metering……………………………………………………………………………..9-7 G. Distribution System Loss………………………………………………………….9-8 H. Water Efficiency Staffing…………………………………………………………..9-8 9.3 California Water Efficiency Partnership…………………………………………………9-8 Section 10 | Plan Adoption, Submittal, and Implementation……………………………………...10-1 10.1 Inclusion of All 2020 Data…………………………………………………………...10-2 10.2 Notice of Public Hearings…………………………………………………………...10-2 A. Public Hearing and Adoption……………………………………………………10-4 B. Plan Submittal and Public Availability…………………………………………..10-4 References…………………………………………………………………………………………...REF-1
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IRWD – 2025 Urban Water Management Plan – Table of Contents
Table of Contents
Appendix A | DWR Checklist………………………………………………………………………….A-1 Appendix B | Reduced Delta Reliance……………………………………………………………….B-1 Appendix C | Outreach Letters and Public Notices………………………………………………...C-1 Appendix D | DWR Submittal Tables…………………………………………………………………D-1 Appendix E | 2025 Water Shortage Contingency Plan……………………………………………..E-1 Appendix F | Basin 8-1 Alternative……………………………………………………………………F-1 Appendix G | 2025 Orange County Demand Projection Model Technical Memorandum……...G-1 Appendix H | Resolutions……………………………………………………………………………...H-1
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IRWD – 2025 Urban Water Management Plan – Table of Contents
Executive Summary and Simple Lay Description of the UWMP Findings
Urban Water Management Plan
In accordance with the Urban Water Management Planning Act, Irvine Ranch Water District (IRWD, District) has prepared the following 2025 Urban Water Management Plan (UWMP, Plan). The Urban Water Management Planning Act is a series of requirements outlined in the California Water Code (CWC). This 2025 UWMP is an update to IRWD’s 2020 UWMP and is in compliance with the requirements of the CWC. IRWD’s 2025 UWMP includes an assessment of its water service reliability to ensure that adequate water supplies are available to meet existing and future demands. It presents an assessment of IRWD’s water service reliability, describes and evaluates sources of water supply, efficient uses of water, demand management measures, recycled water opportunities, and other relevant information and programs through the year 2045. In addition to the water reliability assessments, the plan includes a seismic risk and mitigation assessment, an energy intensity analysis, an evaluation of frequent and severe periods of droughts (as described in the Drought Risk Assessment) and the preparation of an update to IRWD’s Water Shortage Contingency Plan (WSCP). The 2025 UWMP was developed in coordination with the cities and county served by IRWD as well as the regional wholesale water suppliers.
IRWD Water Service Reliability
Since its establishment in 1961, IRWD has conducted comprehensive long-term planning to ensure that sufficient water supplies are available to meet demands in its service area. IRWD’s Water Resources Master Plan (WRMP), IRWD’s primary planning document provides a review of current and potential future potable and non-potable water supplies and development of a preferred supply mix focusing on reliability. The WRMP identifies the optimum mix of water resources to meet normal, dry year, extended drought and emergency requirements. In its planning process, IRWD utilizes historical water use to project existing and planned uses. For purposes of this UWMP, IRWD used normal year demand forecasts developed by regional wholesaler, the Municipal Water District of Orange County (MWDOC).
ES - 1 IRWD – 2025 Urban Water Management Plan – Executive Summary and Lay Description
IRWD’s water supplies include groundwater, imported water from the Metropolitan Water District of Southern California (Metropolitan) purchased through MWDOC, recycled water and local surface water. Since the 1990’s, IRWD has made major investments to diversify its water supply portfolio by increasing local groundwater and recycled water supplies to reduce its reliance on imported water. Imported water is more susceptible to shortage due to long term drought so development of local supplies helps to improve IRWD’s supply reliability. In addition, IRWD has invested in water banking as an emergency storage project that further improves IRWD’s water supply reliability in times of extended drought or supply interruptions.
Hydrologic Conditions and Reporting Period
IRWD’s 2025 UWMP presents the findings of its 2025 water reliability assessment evaluated over a planning horizon from 2030-2045. In addition, IRWD presents the findings of its Drought Risk Assessment over the period 2030 to 2045 under the conditions associated with a normal year, single-dry year and a drought lasting at least five consecutive years. Projections are made in five-year increments. IRWD conducted an assessment of trends in IRWD’s customer water use between 2010-2025 to determine the impact of a single dry year and five consecutive dry years on customer demands. IRWD’s Plan assumes the following: • Normal Year. The year 2012 most closely represents the water supply conditions that IRWD considers available during a normal water year.
• Single Dry Year. IRWD’s potable demands in a single dry year increase by 5 percent, and non-potable demands increase by 10 percent.
• Five-Consecutive-Year Drought. IRWD’s potable demands in the first year of a five-year drought would increase the same as a single dry year, or 5 percent. In year two and three potable demands would increase by an additional 1 percent each year. These increases are primarily due to greater irrigation demands. As the drought progresses and in response to increased conservation outreach, demands would decrease by 1 percent in year four and decrease by another 5 percent in year five. Non-potable demands would increase initially by five percent in the first and second years and by an additional one percent in year three. As the drought progresses, non-potable demands would decrease by two percent in year four and by five percent in year five.
Findings of the 2025 UWMP
The 2025 UWMP provides an assessment and summary of IRWD’s water service reliability through 2045 under the assumptions and sources of information described above. As a reporting document, the UWMP will be updated every five years to reflect changes in water demand and supply projections. The 2025 UWMP satisfies all the content and process requirements mandated by the UWMP Act. Key findings of the 2025 UWMP are as follows: • The total water supplies available to IRWD will meet the projected water demands of existing and planned uses through 2045 under a single dry-year condition and over five
ES - 2 IRWD – 2025 Urban Water Management Plan – Executive Summary and Lay Description
years of consecutive drought, as well as in normal year conditions. This is discussed in Section 7 as well as Appendix D.
IRWD has evaluated its water shortage risk and determined that it has sufficient supply capabilities for a drought period that lasts five consecutive water years based on the driest five-year historic sequence. This Drought Risk Assessment was completed for the period 2026 through 2030. The results are presented in Section 7 as well as Appendix D. IRWD's water resource portfolio consists of imported water, groundwater, recycled water, and local surface water. IRWD has placed an emphasis on becoming less reliant on imported supplies. In fiscal year 2000-01, approximately 56% of IRWD’s total water supplies were from local sources; today, local supplies make up about 80% of IRWD’s supplies. IRWD has developed a comprehensive plan for stages of actions it would undertake to address frequent and severe periods of droughts. Its Water Shortage Contingency Plan includes 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. IRWD continues to invest in water use efficiency measures and sustainable water supplies that helped IRWD reduce its 2020 daily per capita use to 95 GPCD, well below its 2020 reduction target of 171 GPCD. IRWD continues to plan for emergency and catastrophic scenarios including the development of a regional Water System Risk and Resilience Assessment (2025), preparation of an Emergency Operations Plan (2025) and adoption of the regional Orange County Water and Wastewater Multi-Jurisdictional Hazard Mitigation Plan (MJHMP) in 2025. IRWD has invested in emergency storage in Kern County where excess water is stored during wet years for use in extended droughts, supply interruptions or other water shortage emergencies. IRWD has and will continue to regard water quality with paramount importance in protecting its water supply. IRWD owns and operates a state-of-the-art Water Quality Laboratory that is state certified and one of the best equipped water laboratories in southern California. IRWD’s water quality staff continuously monitors the water supply, conducting over a quarter of a million laboratory tests each year from water taken from over 100 sample points throughout the IRWD service area. IRWDs Water Quality Laboratory analyzes these samples to ensure that IRWD’s delivered water meets or exceeds all state and federal drinking water standards.
Future Challenges and Strategies to Manage Reliability Risk
Future challenges to water supply reliability may include drought, natural disasters, water quality concerns, and long-term effects of climate change. Although these challenges primarily present a risk to imported water supply reliability, IRWD has numerous strategies in place to manage reliability risk including:
ES - 3 IRWD – 2025 Urban Water Management Plan – Executive Summary and Lay Description
Continued water use efficiency . As a leader in water use efficiency, IRWD continues to implement a wide range of programs to reduce existing and future customer demands across all sectors. Increased local supplies. IRWD has continually been able to reduce its reliance upon imported water supplies through increased development of local supplies to meet demands. These local supplies include new groundwater projects, increased recycled water treatment capacities and storage. Water quality . IRWD’s mission is to ensure the highest quality drinking water for its customers. IRWD continues to implement water quality treatment strategies to protect water quality for its customers. Emergency preparedness . IRWD maintains emergency operations plans and local hazard mitigation plans to prepare for emergency events including fire, flood, power outages, and others. Water Banking . IRWD has developed a fully operational water banking program which maintains supplemental water supplies that IRWD can rely upon in the event of long-term drought, supply interruptions and other water shortage events. Overall, IRWD has pursued many efforts to better manage reliability risks and to increase water service reliability for its customers. Because of these efforts IRWD water services are considered reliable in every analysis conducted as part of the 2025 UWMP.
ES - 4 IRWD – 2025 Urban Water Management Plan – Executive Summary and Lay Description
1
Section 1 | Introduction
1.1 Urban Water Management Planning Act
This 2025 Urban Water Management Plan (UWMP or Plan) of the Irvine Ranch Water District (IRWD, District) has been prepared in compliance with the California Water Code (CWC) Sections 10610 through 10657, which is known as the Urban Water Management Planning Act (Act). These sections were added by Statute 1983, Chapter 1009, and became effective on January 1, 1984. This UWMP was also prepared in compliance with Section 10608.36 of SB X7- 7, which was enacted in 2009. The Act requires that every urban retail water supplier, providing potable municipal water to more than 3,000 customers or supplying more than 3,000 acre-feet of potable water annually, to prepare and adopt an urban water management plan. IRWD’s 2025 UWMP was prepared in accordance with the requirement that urban water purveyors submit a plan to the California Department of Water Resources (DWR), addressing water supply, demands, conservation measures, and water recycling among other things. IRWD prepared this 2025 UWMP in coordination with the other agencies as indicated. IRWD utilized the DWR “Urban Water Management Plan Guidebook” January 2026 (UWMP Guidebook) in the preparation of this UWMP. There have been no requirement changes since the 2020 UWMP was prepared; only minor changes to definitions. Section 1 provides information on IRWD, the purpose of IRWD Water Resource Planning, and a description of how the UWMP is organized.
1.2 Irvine Ranch Water District (IRWD)
IRWD is a multi-service agency responsible for providing domestic water service, sewage collection and treatment, water recycling, and urban runoff natural treatment in Central Orange County, California. IRWD provides water service to approximately 453,000 residents. IRWD encompasses approximately 181-square miles extending from the Pacific Coast to the foothills of the Santa Ana Mountains, covering elevations ranging from sea level to 1,700 feet. IRWD serves the City of Irvine and portions of Costa Mesa, Lake Forest, Newport Beach, Orange, Tustin, Santa Ana and unincorporated areas of Orange County. Established in 1961 as an independent special district organized under the California Water District Code, IRWD is governed by a five-member, publicly elected Board of Directors responsible for the District’s policies and decision making. Day-to-day operations are supervised by the General Manager and District staff.
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IRWD – 2025 Urban Water Management Plan
IRWD’s mission is to provide high quality water and sewer services in an efficient, cost effective, and environmentally sensitive manner which produces a high level of customer satisfaction. For additional information on IRWD’s service area and customers see Section 3 of this UWMP for IRWD “System Description.”
1.3 Purpose and Importance: IRWD Water Resources Planning
In 1972, IRWD developed master plans for its domestic (potable) and irrigation (non-potable) water systems. As IRWD’s service area developed, the original master plans were updated over the years. In 1991, IRWD combined the potable and non-potable master plans to make up the Water Resources Master Plan (WRMP) and evaluate IRWD’s water resources in their entirety. The WRMP, IRWD’s principal planning document, is a comprehensive document compiling data and analysis that IRWD considers necessary for its planning needs. The WRMP provides the framework for future IRWD water resource planning and decision-making including supply and demand, operations, and financial perspectives. IRWD expects to complete an update of the WRMP in December 2027. Land use within IRWD’s service area has been changing steadily from agricultural to urban development. Additionally, in 1999, two large Marine Corps stations within IRWD’s service area were closed as part of the Federal Base Realignment and Closure. IRWD was involved in various planning studies for the redevelopment and reuse of these bases in coordination with the local jurisdictional agencies. In accordance with Section 10610.2 (a)(4) of the Act, as part of its long- range planning activities, IRWD coordinates closely with various cities and jurisdictions within its service area on their respective general planning to ensure water demand forecasts are consistent with current and future land-use planning. IRWD’s WRMP is used as the foundational document for compliance with enacted legislation (SB221 and SB610), which requires water retailers to demonstrate the sufficiency of water supplies to serve long term demands for certain proposed subdivisions and large development projects subject to the California Environmental Quality Act (CEQA), in addition to existing and planned water supply uses. IRWD stresses the importance of short-term and long-term planning efforts to ensure reliable, affordable water supplies are made available to our customers. This 2025 UWMP allows IRWD to demonstrate the benefits of the District’s water resources planning efforts. Sections 3, 4, 6, 7 and 8 of this UWMP provide detailed information on IRWD’s service area, water systems, supplies and demands, and water supply reliability in accordance with the Act.
1.4 UWMP Organization and Section Summaries
IRWD’s water resources planning efforts and increased water reliability are demonstrated throughout the UWMP and subsequent analyses. This plan provides information on IRWD’s ability to address drought conditions, its short-term and long-term planning needs, historic and projected water supply and demands, as well as options to increase local water resiliency.
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IRWD – 2025 Urban Water Management Plan
IRWD’s 2025 UWMP, is organized in accordance with UWMP Guidebook and contains the following sections:
Section 1: Introduction The introduction provides an overview of the UWMP history, purpose and fundamental requirements. Section 2: Plan Preparation The plan preparation section identifies IRWD’s 2025 UWMP as an individual planning document, indicates the type of year and units of measure used, and describes the outreach and coordination efforts conducted to develop the final 2025 UWMP. Section 3: Service Area Description IRWD’s water supply system is described at length including an extended IRWD background, service area boundaries, population projections, demographics, climatic conditions, and projected land uses for the IRWD service area. Section 4: Water Use Characterization Water use characterization provides historic and current water use, as well as water use projections for the next 20 years. This section includes the methods used to develop IRWD’s water supply and demand projections. Section 5: SBX7-7 Baselines and Targets This section reviews IRWD’s SBX7-7 baselines and targets and demonstrates IRWD’s compliance with the 2020 conservation targets. Section 6: System Supplies This section walks through IRWD’s water system supply portfolio including planned and potential water projects. These potential projects include water transfer and exchange opportunities, local water project coordination efforts, and expanded recycled water options. Section 7: Water Supply Reliability and Drought Risk Assessment An essential section of the 2025 UWMP, Water Supply Reliability and the Drought Risk Assessment (DRA) are included to assess the reliability of IRWD’s supply sources for normal, single-dry, and five-consecutive-dry year conditions. This section includes the new DRA analysis for a consecutive five-year drought period beginning in 2021. Section 8: Water Shortage Contingency Plan This section briefly summarizes the main components of the Water Shortage Contingency Plan (WSCP), past implementation, new requirements, and the process by which IRWD will update the WSCP in the future. The WSCP is included as a separate document in Appendix E.
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IRWD – 2025 Urban Water Management Plan
Section 9: Demand Management Measures Section 9 provides information on IRWD’s existing and expected demand management measures (DMM) to encourage conservation efforts among IRWD customers. Section 10: Plan Adoption, Submittal, and Implementation The final section describes the process IRWD uses to adopt and implement the UWMP. This section includes the specific requirements and provides a documented record of the steps IRWD used to address the adoption, submission, and implementation of the 2025 UWMP and 2025 WSCP. Appendices Standardized Tables Throughout the UWMP tables that are required by DWR include the DWR table number, and are also provided in Appendix D .
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IRWD – 2025 Urban Water Management Plan
2
Section 2 | Plan Preparation
2.1 Basis for Preparing a Plan
Law 10617 “Urban water supplier” means a water supplier, either publicly or privately owned, providing water for municipal purposes either directly or indirectly to more than more than 3,000 customers or supplying more than 3,000 acre-feet of water annually. An urban water supplier includes a supplier or contractor for water, regardless of the basis of right, which distributes or sells for ultimate resale to customers. 10621(a) Each urban water supplier shall update its plan at least once every five years on or before July 1, in years ending in six and one, incorporating updated and new information from the five years preceding each update. In accordance with the California Water Code (CWC), IRWD is an urban water supplier with 3,000 or more service connections and is required by the Act to prepare an UWMP every five years. Several legislative amendments have been made to the CWC since the 2020 UWMP and this 2025 UWMP incorporates all of the new requirements accordingly.
2.2 Public Water Systems
IRWD is considered an urban retail water supplier for the purposes of submitting an UWMP. IRWD includes only one public water system regulated by the State Water Resources Control Board (SWRCB), Division of Drinking Water. DWR Table 2-1 provides information required by DWR regarding public water systems with respect to IRWD. Table 2- 1. DWR Submittal Table Retail: Public Water Systems
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)
Add additional rows as needed CA3010092
Irvine Ranch Water District
132,347
84,438
Total 84,438 NOTES: Volume of water supplied is determined by the end of year water consumption for FY 2024-25 including potable, recycled, and untreated water for all account types. Only active connections are included. 132,347
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IRWD – 2025 Urban Water Management Plan
2.3 Regional Planning and Regional Alliance
IRWD is the largest member agency of the Municipal Water District of Orange County (MWDOC) in terms of service area and overall water use. MWDOC is a wholesale importer of water from the Metropolitan Water District of Southern California (Metropolitan). MWDOC serves all of Orange County except for the cities of Anaheim, Fullerton, and Santa Ana. IRWD coordinated the preparation of this 2025 UWMP directly with MWDOC staff. References to the regional UWMP(s) are made throughout the document as prepared by both Metropolitan and MWDOC. IRWD, as an urban water supplier, developed this 2025 UWMP based solely on the District’s service area. This individual UWMP addresses all requirements of the CWC. IRWD has notified and coordinated with MWDOC and IRWD’s stakeholders on the preparation of the 2025 UWMP. IRWD’s Board of Directors, its governing body, must adopt IRWD’s UWMP before submittal to DWR. IRWD’s required information related to UWMP Identification and participation in a Regional Alliance is shown in DWR Table 2-2 . Table 2- 2. DWR Submittal Table Plan Identification
Submittal Table 2-2: Plan Identification
Name of Regional Alliance or RUWMP (Drop Down List)
Select One
Type of Plan
Individual UWMP If Water Supplier is also a member of a SB X7-7 Regional Alliance, select name from the drop-down. Regional Urban Water Management Plan (RUWMP) If Supplier selected RUWMP, select name from the drop-down.
Orange County 20x2020 Regional Alliance
NOTES:
2.4 Standardized Tables, Year, and Units of Measurement
Law
10644(a)(2) The plan, or amendments to the plan, submitted to the department…shall include standardized forms, tables or displays specified by the department.
IRWD utilized the standardized forms provided by DWR in the 2025 UWMP. The CWC provides water suppliers the authority to report on either a fiscal year (FY) or calendar year basis. In the 2025 UWMP, IRWD reports data on a FY basis with each FY starting on July 1 and ending on June 30. For example, for reporting water use and supply information for 2025, IRWD uses its
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IRWD – 2025 Urban Water Management Plan
FY 2024-2025 data in the units of acre-feet (AF). DWR Table 2-3 includes the information required by DWR related to supplier identification, type of agency, type of reporting year, and the units of measure. Table 2- 3. DWR Submittal Table Supplier Identification
Submittal Table 2-3: Supplier Identification Type of Supplier (select one or both)
Supplier is a wholesale supplier
Supplier is a retail supplier
Fiscal or Calendar Year (select one)
UWMP Tables are in calendar years UWMP Tables are in fiscal years If using fiscal years provide month and date that the fiscal year begins (mm/dd) 07/01
Units of measure used in UWMP (Select from the drop down list). Unit
AF
DWR NOTES: Units of measure (AF, CCF, MG) must remain consistent throughout the UWMP as reported in Submittal Table 2-3. NOTES:
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IRWD – 2025 Urban Water Management Plan
2.5 Coordination and Outreach
IRWD prepared the 2025 UWMP in coordination with regional agencies, water district partners, cities served by IRWD, the county and relevant stakeholders as indicated. Coordination with Wholesale Agencies
Law
10631(h) An urban water supplier that relies upon a wholesale agency for a source of water shall provide the wholesale agency with water use projections from that agency for that source of water in five-year increments to 20 years or as far as data is available. The wholesale agency shall provide information to the urban water supplier for inclusion in the urban water supplier’s plan that identifies and quantifies, to the extent practicable, the existing and planned sources of water as required by subdivision (b), available from the wholesale agency to the urban water supplier over the same five-year increments, and during various water-year types in accordance with subdivision(f). An urban water supplier may rely upon water supply information provided by the wholesale agency in fulfilling the plan informational requirements of subdivisions (b) and (f). IRWD is the largest retail member agency of MWDOC in terms of service area and overall water use. MWDOC is a wholesale importer of water from Metropolitan. MWDOC serves all of Orange County except for the cities of Anaheim, Fullerton and Santa Ana. IRWD coordinated the development of the 2025 UWMP with MWDOC including sharing data, discussing regional UWMP updates, and verifying consistent and accurate exchange of information. DWR Table 2- 4 identifies MWDOC as IRWD’s wholesale water supplier. Table 2- 4. DWR Submittal Table Retail: Water Supplier Information Exchange
Submittal Table 2-4 Retail: Water Supplier Information Exchange Water Code Section 10631(h) The retail Supplier has informed the following wholesale supplier(s) of projected water use. Wholesale Water Supplier Name Municipal Water District of Orange County
IRWD provided MWDOC with its water use projections for imported water supply in five-year increments for the next 20 years. MWDOC incorporated IRWD’s water use projections in its information provided to Metropolitan, the regional wholesaler, of which MWDOC is a member agency. Also, in accordance with 10631(h), for this 2025 UWMP, IRWD relies on the supply information provided in the MWDOC and Metropolitan UWMPs that identifies and quantifies the existing and planned sources of water available to IRWD over the same five-year increments, and during various water-year types in accordance with 10631(f).
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IRWD – 2025 Urban Water Management Plan
Key regional planning and other documents that were used to inform the preparation of IRWD’s UWMP include the following: • Metropolitan Water District 2025 Draft UWMP • Metropolitan Water District 2025 Water Shortage Contingency Plan • Metropolitan Water District 2020 Integration Water Resources Plan (IRP) Regional Needs Assessment • 2025 Orange County Water Demand Projection Model Technical Memorandum (MWDOC) • Orange County Water District 2022 Basin 8-1 Alternative Update • Orange County Water and Wastewater Multi-Jurisdictional Hazard Mitigation Plan • Orange County Water District 2025 OCWD Resilience Plan Coordination with Water Suppliers and the Community Law 10620(d)(3) Each urban water supplier shall coordinate the preparation of its plan with other appropriate agencies in the area, including other water suppliers that share a common source, water management agencies, and relevant public agencies, to the extent practicable. 10621(b) Every urban water supplier required to prepare a plan pursuant to the part shall, at least 60 days before the public hearing on the plan required by Section 10642, notify any city or county within which the supplier provides water supplies that the urban water supplier will be reviewing the plan and considering amendments or changes to the plan. 10642 Each urban water supplier shall encourage the active involvement of diverse social, cultural, and economic elements of the population within the service area prior to and during the preparation of both the plan and the water shortage contingency plan. IRWD serves seven cities, the County, and portions of unincorporated Orange County. Land use within IRWD’s service area has been changing steadily from an agricultural community to an urban area with significant development. IRWD coordinates closely on city general planning with the cities located within IRWD’s service area to determine IRWD’s full build-out demands, especially for currently undeveloped or redeveloping areas. On February 3, 2026, IRWD notified the County of Orange and the seven cities within the IRWD service area (City of Costa Mesa, City of Irvine, City of Lake Forest, City of Newport Beach, City of Orange, and City of Tustin) that IRWD would be reviewing its 2020 UWMP and considering changes to the plan for the 2025 UWMP. These notification letters provided the opportunity for the cities and County of Orange to submit comments regarding IRWD’s 2025 UWMP during the update process. IRWD did not receive any comments from the cities or the County during the preparation of the 2025 UWMP.
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IRWD – 2025 Urban Water Management Plan
In addition, an official public hearing date announcement was sent to all stakeholders, the cities and county in which IRWD provides water service on April 20, 2026. Official notices of the June 22, 2026 public hearing for the 1) 2025 UWMP and 2) 2025 WSCP were published in the Orange County Register, a local southern California newspaper on June 7 and June 14, 2026. IRWD held a public hearing for the 2025 UWMP and 2025 WSCP on Monday June 22, 2026. Copies of IRWD’s notification letters and public announcements to the cities and the County of Orange are included in Appendix C .
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IRWD – 2025 Urban Water Management Plan
3
Section 3 | System Description
3.1 General Description
Law 10631(a) Describe the service area of the supplier, including current and projected population, climate, and other social, economic, and demographic factors affecting the supplier’s water management planning. The projected population estimates shall be based upon data from the state, regional, or local service agency population projections within the service area of the urban water supplier and shall be in five-year increments to 20 years or as far as data is available. The description shall include the current and projected land uses within the existing or anticipated service area affecting the supplier’s water management planning. Urban water suppliers shall coordinate with local or regional land use authorities to determine the most appropriate land use information, including, where appropriate, land use information obtained from local or regional land use authorities, as developed pursuant to Article 5 (commencing with Section 65300) of Chapter 3 of Division 1 of Title 7 of the Government Code. Section 3 provides a general description of IRWD’s formation, governance, location, services, climate, projected population and factors that could affect water management planning. This Section includes a brief description of IRWD’s available water supplies and how land use changes are incorporated into IRWD’s water resource planning. IRWD, a California Water District, formed in 1961, is an independent special district organized under the California Water District Code. IRWD provides potable and non-potable water supply, sewage collection, treatment and disposal, water recycling and urban runoff treatment services. As an independent, not-for-profit public agency, IRWD is governed by a publicly elected five- member Board of Directors (Board). Board members are elected from five divisions and serve four-year terms. The Board is responsible for the District's policies and decision-making. Day-to- day operations are supervised by the General Manager and IRWD staff. IRWD’s mission is to provide high quality water and sewer services in an efficient, cost effective, and environmentally sensitive manner which produces a high level of customer satisfaction. IRWD’s diverse portfolio of water resources ensure reliable supplies during times of drought, regulatory constraints, and emergencies as well as help keep rates low. IRWD is located in the south-central portion of Orange County ( Figure 3 - 1 ). Its service area includes all of the City of Irvine and portions of the surrounding cities of Tustin, Santa Ana, Orange, Costa Mesa, Lake Forest, Newport Beach, and unincorporated areas of the County of Orange. IRWD service area encompasses approximately 181-square miles service. As of 2025,
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IRWD – 2025 Urban Water Management Plan
IRWD has over 132,000 public water system municipal connections (including potable and recycled water).
County of Orange
Figure 3 - 1. IRWD Service Area within Orange County
As discussed more in Section 6, historically, IRWD’s potable water system was largely reliant on imported water supplies from Metropolitan. In 1979, IRWD began developing local water supplies to reduce dependence on costly imported water and now produces drinking water from 25 groundwater wells throughout the service area. Approximately one-half of IRWD’s water supplies comes from local groundwater wells in the Orange County Groundwater Basin (Basin, Basin 8-1). Imported water from Metropolitan makes up approximately one-fifth of IRWD’s supply. Water imported to Orange County comes from two main sources: the Sacramento-San Joaquin Delta (Delta, Bay-Delta) in Northern California conveyed in the State Water Project (SWP) and from the Colorado River through the Colorado River Aqueduct (CRA). IRWD meets about a quarter of the service area’s water demands with recycled water. Every gallon of recycled water used saves a gallon of drinking water. Using recycled water extends drinking water supplies and reduces reliance on costly imported water, helping to improve water supply reliability. On average, IRWD delivers about 26 million gallons of recycled water per day
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IRWD – 2025 Urban Water Management Plan
to 6,500 customers through 585 miles of pipelines. To further offset the need for imported water for non-potable uses, IRWD has continued to expand its recycled water program as demands have increased. IRWD has developed a water banking program in Kern County in which it stores water in wet years for use during dry years and emergencies. Water banking is an important tool for ensuring reliability by augmenting imported water supplies during shortage conditions. By capturing excess water when it is available and storing it in groundwater basins to supplement supplies in dry years, the IRWD water banking program safeguards customers from imported water supply shortages. The banking program is designed to provide enough supplemental water to meet IRWD customers’ needs during critically dry years, supply interruptions or when Metropolitan implements its Water Supply Allocation Plan (WSAP). 3.2 Service Area Boundaries IRWD’s service area boundary is depicted in Figure 3-2 below. In 1997, IRWD acquired neighboring Santa Ana Heights Mutual Water Company with approximately 2,800 connections. In 2001, IRWD merged with the Los Alisos Water District, located in the City of Lake Forest, with approximately 12,400 connections. In 2006, IRWD merged with Santiago Water District, located within the unincorporated area of Orange County, with 740 connections. In 2008, IRWD merged with Orange Park Acres Mutual Water Company, located within the City of Orange, with approximately 530 connections. The unincorporated portions of IRWD’s service area, as shown on Figure 3-2 , fall within the County of Orange jurisdiction. IRWD’s records show 132,347 connections which served a total of 84,438 AF of water in FY 2024-25.
Service Area Cities: Costa Mesa Irvine Lake Forest
Newport Beach Orange Santa Ana
Tustin
Service Area County: Orange County, California
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IRWD – 2025 Urban Water Management Plan
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