The defining fact of California water is the spatial mismatch between supply and demand. Roughly 75% of precipitation falls north of Sacramento, while ~75% of demand sits south of it (DWR). The Sierra Nevada snowpack is California's largest single reservoir — historically holding around 15 million acre-feet of usable water as snow, then releasing it during spring and summer when demand peaks. The Colorado River, fed by the Rocky Mountains, is California's largest out-of-state supply.

Three engineered systems redistribute this water to where people live:

1. Central Valley Project (CVP) — federal, USBR-operated, primarily agricultural, ~5 MAF/yr to agriculture and ~600,000 AF/yr to M&I customers (USBR).
2. State Water Project (SWP) — DWR-operated, ~70% urban / ~30% agricultural, 29 long-term contractors with Table A entitlements totaling ~4.17 MAF/yr (DWR — SWP Contractors).
3. Colorado River Aqueduct (CRA) — operated by MWD, 242 miles from Lake Havasu to Lake Mathews, delivering MWD's apportioned share of California's 4.4 MAF Lower Basin entitlement (MWD — Colorado River).

Together these three projects move on the order of 10–12 MAF/yr — comparable in scale to the entire Colorado River's natural flow.

flowchart LR
    subgraph North["WET NORTH (75% of precipitation)"]
        SN[Sierra Nevada snowpack]
        NRiv[Northern CA rivers]
    end
    subgraph East["COLORADO BASIN"]
        CR[Colorado River]
    end
    subgraph Projects["ENGINEERED CONVEYANCE"]
        CVP_p[CVP - federal/USBR
~5.6 MAF/yr]
        SWP_p[SWP - state/DWR
~4.17 MAF/yr Table A]
        CRA_p[Colorado River Aqueduct
MWD ~1 MAF/yr]
    end
    subgraph South["DRY SOUTH (75% of demand)"]
        Urban[Urban SoCal
19M people]
        Ag[Central Valley ag]
        Bay[Bay Area cities]
    end
    SN --> CVP_p
    SN --> SWP_p
    NRiv --> CVP_p
    CR --> CRA_p
    CVP_p --> Ag
    CVP_p --> Bay
    SWP_p --> Urban
    SWP_p --> Ag
    CRA_p --> Urban

Central Valley Project (CVP)

Authorized 1935; built and operated by the U.S. Bureau of Reclamation. Major facilities: Shasta Dam, Trinity Dam, Folsom Dam, the Delta-Mendota Canal, the Friant-Kern Canal, New Melones Reservoir. Most CVP supply serves Central Valley agriculture under long-term water-service contracts; a smaller share serves M&I customers (mostly in Sacramento and the Bay Area).

The Central Valley Project Improvement Act (CVPIA, 1992) added fish and wildlife as a co-equal project purpose, dedicating 800,000 AF/yr of project yield to environmental uses. Since then, South-of-Delta agricultural contractors have been chronically curtailed — in many dry years receiving 0–25% of contracted volumes. M&I has statutory priority; in 2026, South-of-Delta M&I received 100% while South-of-Delta agricultural contractors received 55% (USBR allocations; CRS R45342).

State Water Project (SWP)

Authorized by voters in 1960 (Burns-Porter Act). Operated by DWR. Anchor facilities: Oroville Dam (largest reservoir in the system), Banks Pumping Plant in the South Delta, the 444-mile California Aqueduct, San Luis Reservoir (shared with CVP), and the Edmonston Pumping Plant (lifts water 1,926 feet over the Tehachapis — the largest single lift of any aqueduct in the world).

29 long-term contractors; the largest is MWD at ~1.911 MAF/yr Table A entitlement — about 46% of the SWP. Other major contractors include Kern County Water Agency (ag), Alameda County Water District, Santa Clara Valley Water (Valley Water), and Coachella Valley Water District (which uses its allocation as part of a Colorado-for-SWP exchange with MWD).

The SWP is California's single largest electricity consumer (pumping is energy-intensive) and the largest electricity producer among state utilities (the system includes hydropower at Hyatt, Devil Canyon, and other plants).

SWP annual allocation percentages illustrate hydrologic and regulatory volatility:

Source: DWR — SWP Allocation history.

Colorado River

Governed by the "Law of the River" — a stack of compacts, statutes, treaties, and decisions. The key elements:

• Colorado River Compact (1922) — divided the basin into Upper and Lower halves, each allocated 7.5 MAF/yr.
• Boulder Canyon Project Act (1928) — apportioned the Lower Basin: California 4.4 MAF, Arizona 2.8 MAF, Nevada 0.3 MAF.
• 1944 U.S.–Mexico Treaty — guaranteed Mexico 1.5 MAF/yr.
• Arizona v. California (1963) — Supreme Court confirmed the apportionment.
• 2007 Interim Guidelines — set shortage-sharing rules for Lake Mead elevations.
• 2019 Drought Contingency Plan (DCP) — additional shortage tiers.
• Quantification Settlement Agreement (QSA, 2003) — among IID, CVWD, MWD, SDCWA, the State, and Interior — capped California at 4.4 MAF after decades of using ~5.2 MAF in surplus, and structured the IID-to-SDCWA transfer (up to 200,000 AF/yr, the largest ag-to-urban transfer in U.S. history). Through 2047 (SDCWA QSA Transfer).
• 2023 Lower Basin agreement (extended through 2026) — California, Arizona, and Nevada committed to conserving up to 3 MAF cumulatively (1.6 MAF California share) (CalMatters).

MWD holds basic priority for 550,000 AF/yr; in practice it accesses up to ~1.2 MAF in surplus or transferred years.

flowchart TB
    Compact[Colorado River Compact 1922
Upper 7.5 / Lower 7.5 MAF]
    Compact --> Boulder[Boulder Canyon Act 1928
CA: 4.4 / AZ: 2.8 / NV: 0.3 MAF]
    Boulder --> Treaty[1944 Mexico Treaty
1.5 MAF to Mexico]
    Treaty --> AZv[Arizona v. California 1963
Supreme Court confirmation]
    AZv --> QSA[QSA 2003
CA capped at 4.4 MAF]
    QSA --> Trans[IID→SDCWA transfer
up to 200K AF/yr to 2047]
    QSA --> Guide[2007 Interim Guidelines
Lake Mead shortage tiers]
    Guide --> DCP[2019 Drought Contingency Plan]
    DCP --> LB23[2023 Lower Basin Agreement
CA conserve 1.6 MAF thru 2026]

Three urban systems built their own out-of-region surface water sources before the SWP era and continue to depend on them:

• SFPUC's Hetch Hetchy Regional Water System — ~265,000 AF/yr to 2.6 million Bay Area customers; ~80% of SFPUC's portfolio. Built 1913–34 under the Raker Act. Sources include the Tuolumne River impounded at Hetch Hetchy Reservoir in Yosemite (BAWSCA).
• EBMUD's Mokelumne Aqueduct — entitled to up to 364,000 AF/yr; reservoirs Pardee (198,000 AF) and Camanche (417,000 AF). 90-mile aqueduct from the Sierra to Oakland. Supplemented by Sacramento River CVP supply during drought via the Freeport Regional Water Project (EBMUD).
• LADWP's Los Angeles Aqueduct — completed 1913 (the Mulholland aqueduct); a second aqueduct added in 1970. Historical capacity ~480,000 AF/yr from the Owens Valley and Mono Basin. Now sharply constrained by the 1994 Mono Lake Decision 1631 (SWRCB) and Owens Lake dust mitigation requirements; recent delivery averages closer to 250,000 AF/yr (LADWP — Sources of Supply).

A useful frame: each of California's three major coastal metros has its own "imperial aqueduct" — SF reached east, LA reached north, EBMUD reached east — predating or alongside the federal/state projects. SDCWA never built its own; it relied on MWD until the QSA-era diversification.

Groundwater supplies ~40% of California water use in normal years and up to 60% in droughts. For urban agencies the share varies from near-zero (SFPUC) to ~85% (Fresno) to ~100% (some adjudicated LA basins).

Three regulatory regimes apply:

• Adjudicated basins (~30 statewide, mostly in Southern California — San Fernando, Raymond, Central, West Coast, Main San Gabriel, Chino) have court-decreed pumping rights and a Watermaster; SGMA largely exempts them.
• SGMA-managed unadjudicated basins — high and medium priority basins under SGMA must have a Groundwater Sustainability Agency (GSA) and a Groundwater Sustainability Plan (GSP). 21 basins are designated critically overdrafted (COD) and must reach sustainability by 2040; other high/medium-priority basins by 2042 (DWR — SGMA).
• Unmanaged low/very-low priority basins remain locally governed without SGMA plans.

SGMA (the Sustainable Groundwater Management Act) is a three-bill package (AB 1739, SB 1168, SB 1319) signed in September 2014. It is California's first statewide groundwater regulation in a state that previously treated groundwater as an essentially unregulated common-pool resource. DWR evaluates GSP adequacy; the State Water Board can intervene with probation/interim plans where GSPs are inadequate. The Tulare Lake Subbasin entered probation in 2024; Tule and Kaweah have been referred (Allen Matkins — SGMA at 10 Years).

Subsidence is the most visible failure mode of unmanaged pumping. In the San Joaquin Valley, decades of overpumping have caused tens of feet of land subsidence, crimping the Friant-Kern Canal's downstream capacity by 60% over a 33-mile stretch (PPIC — Subsidence).

flowchart TD
    GW[California Groundwater Basins]
    GW --> Adj[Adjudicated Basins ~30
Court-decreed rights + Watermaster
Mostly SoCal: San Fernando, Chino, etc.]
    GW --> Managed[SGMA-Managed Basins
96% of groundwater use]
    GW --> Unmng[Low/Very-Low Priority
Locally governed, no SGMA plan]
    Managed --> COD[21 Critically Overdrafted
Sustainability by 2040]
    Managed --> HM[High/Medium Priority
Sustainability by 2042]
    COD --> GSA[Groundwater Sustainability Agency]
    HM --> GSA
    GSA --> GSP[Groundwater Sustainability Plan]
    GSP --> DWReval{DWR adequacy review}
    DWReval -->|Approved| OK[Local control continues]
    DWReval -->|Inadequate| Prob[State Water Board probation
Tulare Lake 2024
Tule + Kaweah referred]

Recycled water (three categories)

• Non-potable reuse (NPR) — Title 22 tertiary-treated water, "purple pipe" delivery for irrigation, cooling, toilet flushing. IRWD is the national leader: 28% of its supply is recycled, distributed through 572 miles of purple pipe (IRWD — Recycled Water).
• Indirect potable reuse (IPR) — purified water augments a groundwater basin or surface reservoir before potable treatment. Orange County Water District's Groundwater Replenishment System (GWRS) is the world's largest at 130 MGD (~145,000 AF/yr) after its 2023 final expansion, serving 1 million people (OCWD GWRS).
• Direct potable reuse (DPR) — purified water introduced directly into the distribution system or upstream of a treatment plant. SWRCB adopted DPR regulations on December 19, 2023; OAL approved August 6, 2024; effective October 1, 2024 (SWRCB DPR).

Major projects in the pipeline: Pure Water San Diego (30 MGD Phase 1, 83 MGD at buildout, ~⅓ of city supply by 2035); Pure Water Southern California (MWD / LA County Sanitation Districts joint project, 150 MGD at full scale) (Pure Water SD; MWD Pure Water Southern California).

Costs: ~$1,000–$2,000/AF for non-potable, ~$1,800–$2,500/AF for purified water suitable for IPR/DPR.

flowchart LR
    WW[Wastewater Treatment Plant]
    WW --> NPR[Non-Potable Reuse NPR
Title 22 tertiary
'Purple pipe' irrigation/cooling
~$1,000-2,000/AF]
    WW --> Adv[Advanced Purification
MF + RO + UV/AOP]
    Adv --> IPR[Indirect Potable Reuse IPR
Inject to groundwater or reservoir
OCWD GWRS = 130 MGD]
    Adv --> DPR[Direct Potable Reuse DPR
To distribution or upstream of WTP
Effective Oct 1 2024]
    IPR --> Tap[Customer tap]
    DPR --> Tap
    NPR --> Irr[Landscape / industrial]

Desalination

California has 12 operating seawater desalination plants. Anchor facilities:

• Claude "Bud" Lewis Carlsbad Desalination Plant — 50 MGD / ~56,000 AF/yr, sold to SDCWA at $2,000–$2,725/AF. Largest seawater desal in the Western Hemisphere (Wikipedia).
• Santa Barbara Charles Meyer Plant — 3,125 AF/yr at ~$2,700/AF.
• Cal-Am Monterey Peninsula Water Supply Project — ~6,250 AF/yr, in permitting; estimated $3,700–$5,700/AF.

The 2015 Ocean Plan Desalination Amendment sets statewide rules for subsurface intakes, brine discharge dilution, and mitigation. Public opposition has slowed expansion — notably the Coastal Commission's 2022 rejection of Poseidon Huntington Beach (SWRCB Ocean Plan).

Stormwater capture

Historically negligible, now growing under two policy drivers:

• LA County Measure W (Safe, Clean Water Program) — passed November 2018, 2.5¢/sq-ft impermeable-surface parcel tax raising ~$300M/year. Capture goal: 300,000 AF/yr by 2045 (Safe Clean Water LA).
• San Francisco Non-Potable Water Ordinance (Article 12C) — requires new buildings ≥100,000 sq ft to install onsite reuse systems (SFPUC Onsite Water Reuse).

California has experienced four major droughts in the past 50 years; each has produced its own statutory/regulatory legacy.

The pattern: each drought ratchets the regulatory/technical apparatus tighter, and the wet years that follow rarely roll any of it back.

The most consequential institutional distinction for an analyst to internalize:

Department of Water Resources (DWR)

• Sits under the California Natural Resources Agency.
• Established by the Legislature in 1956, originally to build and operate the SWP.
• Mission: sustainably manage California's water resources in cooperation with other agencies (DWR — About).
• Statutory authorities: dam safety, flood management, SWP operations, SGMA technical oversight (GSP review/approval), Urban Water Management Plan review, water-use efficiency programs.

State Water Resources Control Board (SWRCB)

• Sits under CalEPA, with nine Regional Water Quality Control Boards.
• Mission: preserve, enhance, and restore California's water resources and drinking water; ensure proper resource allocation.
• Statutory authorities: Water Code (water rights), Porter-Cologne Water Quality Control Act (1969), federal Clean Water Act, Safe Drinking Water Act.
• Administers ~46,000 water rights, regulates ~7,400+ public drinking water systems, distributes ~$1B/year in water-infrastructure financial assistance.
• The Division of Drinking Water (DDW) was transferred from CDPH to SWRCB on July 1, 2014 under SB 851/861. DDW holds primacy for the Safe Drinking Water Act.

Practical division

Coordination

During drought, DWR and USBR file joint Temporary Urgency Change Petitions (TUCPs) with SWRCB to modify Bay-Delta flow standards (D-1641); SWRCB issues Temporary Urgency Change Orders (TUCOs). The agencies also jointly fund community drought outreach.

For SGMA: DWR is the technical reviewer of GSPs; SWRCB is the "backstop" — it can place a basin on probation and impose interim plans if local GSAs fail or DWR finds a GSP inadequate. Basins return to DWR jurisdiction once issues resolve.

The mnemonic an analyst should carry: DWR does supply, planning, infrastructure, flood. SWRCB does quality, rights, allocations, drinking water permitting. CPUC does investor-owned rates. USBR does federal water.

flowchart TD
    Gov[Governor of California]
    Gov --> NRA[California Natural
Resources Agency]
    Gov --> CalEPA[CalEPA]
    Gov --> CPUC[CPUC
Public Utilities Commission]
    Fed[U.S. Federal] --> USBR[USBR
Bureau of Reclamation]
    NRA --> DWR[DWR
Department of Water Resources]
    CalEPA --> SWRCB[SWRCB
State Water Resources Control Board]
    SWRCB --> DDW[Division of Drinking Water
moved from CDPH 2014]
    SWRCB --> WR[Division of Water Rights
~46,000 rights]
    SWRCB --> RB[9 Regional Water Quality
Control Boards]
    DWR -.-> Functions1[SWP operations
UWMP review
SGMA technical
Dam safety / Flood]
    SWRCB -.-> Functions2[Water quality
Drinking water permits
Water rights
SAFER / eAR]
    USBR -.-> Functions3[CVP operations
Colorado River]
    CPUC -.-> Functions4[Investor-owned utility rates
GRC every 3 years]

California has ~3,000 community water systems (CWS — year-round residential service) plus another ~4,000 non-community systems (NTNC schools/workplaces, transient TNC) (California WaterBlog).

CWS ownership splits roughly:

Within those, four legal forms account for the bulk of population served:

(a) City / municipal water department

• Enabling law: California Constitution Article XI (charter/general-law city authority).
• Governance: city council (elected) sets policy and rates; some charter cities (LA) use an appointed Board of Water and Power Commissioners.
• Examples: LADWP (~4M served), San Diego Public Utilities, San Francisco PUC, City of Santa Clara.
• Oversight: SWRCB DDW for water quality; not CPUC-regulated.
• Rate-setting: council adoption with Prop 218 majority-protest hearing.
• Strengths: integration with land use, fire, stormwater; cheap municipal bond financing.
• Weaknesses: political pressure on rates; "general fund transfers" can be contested.
• Count: ~315 cities operate CWSs in California.

(b) Special district

The most diverse category. California has ~3,300 special districts statewide; ~595 operate community water systems. CSDA (California Special Districts Association) is the trade association.

Sub-types:

Counts of CWS-operating districts (Pace et al., 2018): ~165 County Water Districts, ~185 CSDs, ~77 County Service Areas, ~53 PUDs, ~51 Irrigation Districts, ~32 California Water Districts, ~31 Municipal Water Districts.

Taxing power: most can levy ad valorem property taxes (subject to Prop 13 limits), benefit assessments, and standby charges. Oversight: SWRCB-DDW (water quality); LAFCO (formation, boundaries, dissolution); State Controller (financial reporting). Rate-setting: board adoption with Prop 218 process.

(c) Mutual water company

• Enabling law: Corporations Code §14300–14318 — nonprofit mutual benefit corporations owned by water-using shareholders (one share typically tied to a parcel).
• Governance: shareholder-elected board; shares often appurtenant to land. Many are legacy ag-turned-suburban systems formed in the early 1900s.
• Oversight: SWRCB-DDW for drinking water quality. Generally NOT CPUC-regulated (mutuals serving only their shareholders are exempt under PUC §2705).
• AB 240 (Eng, 2013; effective Jan 1, 2014): imposed open-meeting, agenda, minutes, records-inspection, annual budget in open session, CPA financial review, board-member training (every 6 years), and assessment authority requirements on mutuals operating public water systems (AB 240).
• SB 552 (2021) added drought-resilience planning obligations for small mutuals.
• Trade association: California Association of Mutual Water Companies (CalMutuals) (CalMutuals).
• Count: ~582 mutual water companies operate CWSs — the most numerous private form. Most are small.
• NOT subject to Prop 218 (they are not public agencies).
• Strengths: local control, ownership aligned with users.
• Weaknesses: capital-poor, technical/managerial capacity gaps; over-represented among failing systems.

(d) Investor-owned (private) utility

• Enabling law: Public Utilities Code Division 1; defined as "public utilities" under Cal. Const. Art. XII.
• Governance: corporate, shareholder-owned.
• Oversight: California Public Utilities Commission (CPUC) Water Division sets rates and service standards; SWRCB-DDW for quality. CPUC regulates 100+ investor-owned water/sewer utilities.
• Rate-setting: General Rate Case (GRC) filed every 3 years for Class A (≥10,000 connections); CPUC sets revenue requirement, capital plan, and tariff schedule. NOT subject to Prop 218 (CPUC GRC Process).
• Examples (Class A): California Water Service (Cal Water — largest), San Jose Water Company, Golden State Water (American States Water), Suburban Water Systems, Liberty Utilities (Park Water/Apple Valley Ranchos), Great Oaks Water.
• Count: ~220 investor-owned CWSs; serve 15–16% of Californians; ~95% of IOU customers are on the 9 largest Class A utilities.
• Strengths: access to capital markets; standardized regulatory framework; mandated low-income (LIRA/CARE) programs.
• Weaknesses: profit motive can drive rate growth; recent GRCs have requested 20–25%+ increases over 3 years.

Comparison table

flowchart TD
    Total[~3,000 Community Water Systems
~7,400 total Public Water Systems]
    Total --> Pub[Public ~1,166
Most population served]
    Total --> Priv[Private ~1,729
Most systems, smaller]
    Pub --> City[City Departments ~315
LADWP, SFPUC, San Diego PUD]
    Pub --> SD[Special Districts ~595]
    SD --> CWD[County Water District
~165 - CVWD]
    SD --> MWDist[Municipal Water District
~31 - EBMUD, LVMWD, MWD]
    SD --> CalWD[California Water District
~32 - IRWD, Westlands]
    SD --> ID[Irrigation District
~51 - Imperial, Modesto]
    SD --> CSD[Community Services District
~185]
    SD --> Other_SD[PUD, CWA, etc.
~130]
    Priv --> Mut[Mutual Water Co ~582
Corp Code §14300
NOT subject to Prop 218]
    Priv --> IOU[Investor-Owned ~220
CPUC GRC every 3 yrs
Cal Water, Golden State, Liberty]
    Priv --> POther[Other ~927
MHP, HOA]

Definitions (Water Code §10608.12):

• Urban retail water supplier — serves end-use customers directly; accountable for water-use efficiency targets, demand management, water-loss audits.
• Urban wholesale water supplier — sells water at wholesale to other water purveyors (not end users); 3,000+ AF/yr or 3,000+ service connections.

UWMP tables labeled "R" apply only to retailers; "W" tables only to wholesalers; water-loss audits are retailer-only. Wholesalers may file individually or in regional/joint UWMPs.

MWD as the canonical wholesaler

• Created by the Metropolitan Water District Act of 1927/1928 (not a JPA — a state-chartered regional wholesaler).
• 38-member board representing 26 member agencies (14 cities, 11 municipal water districts, 1 county water authority — SDCWA).
• ~19 million people served; ~5,200 sq mi across six SoCal counties.
• Rate stack: volumetric supply rate (historically Tier 1 / Tier 2 — discontinued for CY 2025/26 as the 2014 Purchase Order agreements expired), Readiness-to-Serve (RTS) Charge (10-yr rolling average firm deliveries), Capacity Charge (peak-day demand), plus Supply Reliability, Customer Service, Emergency Storage, and Infrastructure Access components (MWD Rate Handbook).
• Historically also collected an ad valorem property tax (0.25–0.50% of assessed value) — now capped and a minor revenue source.

Other major wholesalers

• San Diego County Water Authority (SDCWA) — created by 1944 special legislation; wholesales to 22 retail member agencies via a 34-director board; ~3.3M served.
• Santa Clara Valley Water District (Valley Water) — countywide wholesale supply + groundwater management + flood protection; relies on municipal and investor-owned retailers (San Jose Water, City of Mountain View, etc.) for end-user delivery.
• Municipal Water District of Orange County (MWDOC) — MWD member that wholesales to 28 OC retailers.
• Calleguas MWD — wholesales to Ventura County retailers.
• Zone 7 Water Agency — Livermore-Amador Valley.

Wholesale + retail chain

In a chain like MWD → MWDOC → City of Anaheim, each level files its own UWMP. Supply assumptions in the retailer UWMP must reconcile with wholesaler delivery commitments. The wholesaler files supply-and-demand projections to its member agencies; member agencies confirm or revise the projections in their own UWMPs. This is one of the most consequential data-quality interfaces in the entire system — and the place where wholesaler over-allocation or retailer under-projection becomes most visible.

flowchart TD
    Sources[SWP + Colorado River + Local]
    Sources --> MWD[MWD
Wholesaler-of-wholesalers]
    MWD --> MWDOC[MWDOC
OC sub-wholesaler]
    MWD --> SDCWA[SDCWA
SD wholesaler]
    MWD --> LADWP[LADWP
direct member-retailer]
    MWD --> Calleguas[Calleguas MWD
Ventura wholesaler]
    MWDOC --> IRWD_r[IRWD]
    MWDOC --> Anaheim[City of Anaheim]
    MWDOC --> OCRet[~28 OC retailers]
    SDCWA --> SDCity[City of San Diego]
    SDCWA --> Sweetwater[Sweetwater Authority]
    SDCWA --> SD22[~22 SD member retailers]
    LADWP --> LACust[4M LA customers]
    IRWD_r --> IRWDCust[~425K customers]
    Anaheim --> AnaCust[Anaheim customers]
    SDCity --> SDCust[San Diego customers]

Each box in this chain files its own UWMP; supply numbers at each level must reconcile up the chain.

From the 2024 SAFER Drinking Water Needs Assessment (SWRCB):

• 385 failing public water systems serving 913,500 Californians (98% of CA on systems meeting standards).
• 613 at-risk systems serving 1.5 million.
• 727 high-risk state small water systems.
• 143,663 high-risk domestic wells.
• 3% of CWSs face high affordability burden, 10% medium.
• Drives allocation of ~$855M in SAFER funding.

Concentration: ~95% of Californians get water from ~475 "large" or "very large" systems. Most small systems are private (68%). The long tail of small mutuals, mobile-home-park systems, and CSDs serving a few hundred connections each is where the affordability and water-quality risk concentrates.

Statutory basis

Urban Water Management Planning Act, Water Code §§ 10610-10657, effective January 1, 1984.

Who must file

• Any urban water supplier providing >3,000 service connections OR >3,000 AF/year of municipal/industrial water.
• Failure to adopt a compliant UWMP disqualifies the supplier from most state grants and loans (DWR funding, SWRCB SRF loans, drought funding).

Cycle

• Every 5 years — 2010, 2015, 2020, 2025...
• 2020 UWMPs due to DWR July 1, 2021 (extended from 2020 due to COVID and additional reporting requirements).
• 2025 UWMPs due July 1, 2026.

Contents

• Service-area description (population, climate, land use).
• Existing and planned supplies by source.
• 20-year demand projections (typically to 2045 for the 2020 cycle).
• Demand Management Measures (DMMs) — narrative on the supplier's conservation programs.
• Recycled-water plan.
• Reliability assessment — normal, single-dry, multiple-dry year (5 consecutive).
• SB X7-7 baseline/target compliance (20×2020).
• Water Shortage Contingency Plan (WSCP) — six standard shortage levels (≤10% through >50%), response actions, communication protocols, financial-impact analysis.
• 5-year Drought Risk Assessment (DRA) — added in the 2020 cycle (Water Code §10635(b)).
• Annual water-loss audit (SB 555, 2015).
• Climate change vulnerability narrative.

DWR role

DWR reviews UWMPs for completeness against Water Code requirements. It does not "approve" the plan substantively, but issues a determination of compliance/non-compliance. Non-compliance blocks eligibility for most state funding.

timeline
    title UWMP - Layered Statutory Requirements
    1983 : Urban Water Management Planning Act (AB 797) : Original 5-year UWMP cycle
    2009 : SBX7-7 / 20×2020 added : Per-capita reduction target
    2015 : SB 555 added : Annual water-loss audits
    2018 : SB 606 / AB 1668 : WSCP + DRA + Urban Water Use Objectives
    2020 : 2020 UWMP cycle (due July 2021) : First cycle w/ DRA
    2024 : UWUO final regs (July 3) : Indoor 47 gpcd by 2025
    2025 : 2025 UWMP cycle (due July 2026) : Active cycle
    2030 : Indoor 42 gpcd standard : Future target

SB 606 / AB 1668 linkage

"Making Conservation a California Way of Life" replaced the gallons-per-capita-per-day SBX7-7 framework with site-specific Urban Water Use Objectives compounded from:

• Indoor residential (47 gpcd by 2025, 42 gpcd by 2030).
• Outdoor residential.
• Outdoor CII with dedicated irrigation meters.
• Water loss.
• Variances (livestock, etc.).

The final State Water Board regulations were adopted July 3, 2024, with phased compliance through 2030+. The framework feeds directly into UWMP demand projections and WSCP/DRA architecture.

Where 2020 UWMP data lives

• DWR's WUEdata Portal (wuedata.water.ca.gov) hosts all submitted 2020 and 2015 UWMPs.
• 2020 UWMP Data Export Tables — published on data.ca.gov and lab.data.ca.gov as a zip of 99 TSV files with standardized table outputs across all submittals, plus a data dictionary (2020 UWMP Data Export).
• A multi-sheet XLSX workbook version also exists. Note: the XLSX was last updated in 2024 while the TSV files were last updated in 2023 — version drift between formats.

These are the two newest layers in the UWMP stack, added in the 2020 cycle:

WSCP

• Six standard shortage levels: ≤10%, 10–20%, 20–30%, 30–40%, 40–50%, >50%.
• Mandatory and conditional response actions at each level.
• Adoptable as a stand-alone document amendable between UWMP cycles.
• Must include: annual DRA procedures, communication protocols, legal-authority description, financial-impact analysis.

flowchart LR
    L1["Level 1
≤10% shortage
Voluntary call"]
    L2["Level 2
10-20%
Outdoor restrictions"]
    L3["Level 3
20-30%
Drought surcharges"]
    L4["Level 4
30-40%
Mandatory cuts"]
    L5["Level 5
40-50%
Enforcement actions"]
    L6["Level 6
>50%
Emergency rationing"]
    L1 --> L2 --> L3 --> L4 --> L5 --> L6
    style L1 fill:#e8f5e9,color:#000
    style L2 fill:#fff9c4,color:#000
    style L3 fill:#ffe0b2,color:#000
    style L4 fill:#ffccbc,color:#000
    style L5 fill:#ef9a9a,color:#000
    style L6 fill:#e57373,color:#fff

DRA

• Assesses reliability across five consecutive dry years starting from the year after the assessment, using historic hydrology and source-by-source reliability.
• Filed annually with DWR via the Annual Water Supply and Demand Assessment (separate from the 5-year UWMP).

The DRA is the mechanism that turns the 5-year UWMP into a rolling, forward-looking risk plan. It is also the first piece of the UWMP apparatus that explicitly demands probabilistic supply analysis — most agencies still use deterministic worst-case hydrology, but DWR's 2020 Guidebook encourages probabilistic methods.

See §4 above. Operationally, an analyst tracking an agency in a SGMA basin should know:

• The GSA governing the basin (often a JPA of overlying retailers).
• The GSP submittal year (2020 for COD basins, 2022 for other high/medium-priority).
• The DWR determination (Approved / Incomplete / Inadequate).
• Any State Water Board probation action.
• The sustainable yield and annual pumping vs. that yield.

Most urban UWMP supply tables now include a "groundwater" line that explicitly references the GSP's allowable pumping volume — that linkage is where SGMA constraints flow through to the UWMP demand-side.

A small ecosystem of consulting firms produces most California UWMPs and rate studies. Major players:

• Water Systems Consulting, Inc. (WSC)
• Kennedy/Jenks Consultants
• Woodard & Curran (absorbed RMC Water + Environment)
• Stantec
• Hazen & Sawyer
• Maddaus Water Management
• Carollo Engineers
• Raftelis (financial / rate studies)
• NBS (financial / rate studies)
• West Yost Associates

UWMP consultant fee benchmarks (2024–2025 awards)

Sources: Folsom Council 7/8/2025; MPWMD Board 5/19/2025; Montecito RFP.

Rate study consultant fee benchmarks

Pattern

• Small-agency UWMPs: ~$50k–$150k.
• Mid-sized agencies: ~$150k–$300k.
• Large multi-system wholesalers (MWD, SDCWA, City of San Diego): often >$300k–$500k, typically bundled with capacity-fee updates and Prop 218 noticing.
• Prop 218 mailing/noticing adds $1–$3 per parcel in printed bilingual notices plus hearing logistics — for a 50,000-parcel agency, $75k–$150k on top.

Industry size estimate: with ~440 UWMP-filing agencies, a 5-year cycle, and an average ~$150k UWMP plus a separate ~$150k rate study (often on overlapping cadences), the California water consulting market for these two artifacts alone is on the order of $25–50M per cycle / $5–10M annually. This is the consultant fee economy the user's MVPi intervention will operate alongside.

The eAR is the SWRCB Division of Drinking Water's annual technical report required of all public water systems — community water systems, NTNC nonprofits, and small water suppliers (15+ service connections or serving 25+ people daily). Legal authority: California Health & Safety Code § 116530.

• Cycle: form opens February 1, due April 1 of each year.
• Structure: 18 sections plus a finalize step.
• Topics covered: system inventory, sources, treatment, distribution, operator certifications, cross-connection control, water loss, production/delivery (Section 6), and financial/affordability data (Section 8).

Section 8 — the affordability triad

Granularity expansion (RY 2023 & RY 2024)

Section 8 was substantially expanded for the 2023 reporting year to feed the SAFER Drinking Water Needs Assessment's Affordability component. RY 2023 was the first cycle in which restructured rate/financial fields were collected at the level needed for state-level affordability analysis. RY 2023 and RY 2024 are currently published as separate downloadable files by section.

Public dataset (Section 6 extract)

Drinking Water — Public Water System Annually Reported Water Production and Delivery Information 2013–2022 (data.ca.gov). Contains:

• Monthly water produced by source (groundwater, surface, purchased, recycled).
• Monthly deliveries by customer class.
• Metered vs. unmetered connections.
• Population, service-connection counts.

Format: CSV / ZIP / XLSX data dictionary. Update frequency: "irregular."

Training

SWRCB hosts dedicated tutorial videos for each of the 18 sections (including a separate Section 8C: Affordability YouTube tutorial), plus "Brown Bag Training" recordings (eAR page; Section 8C tutorial).

Caveats

• Self-reported.
• Contains free-text fields (especially rate structures in 8A — resists normalization).
• Historical long tail of late submitters.
• The 2013–2022 production-and-delivery dataset is a clean Section-6 extract but lags real-time and excludes the newer rates fields.

SAFER = Safe and Affordable Funding for Equity and Resilience. Codified through Senate Bill 200 (Monning, 2019), signed by Governor Newsom on July 24, 2019, and operationalized via the Safe and Affordable Drinking Water (SADW) Fund.

• Funding mechanism: 5% of the Greenhouse Gas Reduction Fund, up to $130 million per year, sunset June 30, 2030. Eligible uses: O&M, consolidations, replacement water, administrator services for small failing systems.
• Program purpose (verbatim): "ensure Californians who lack safe, adequate, and affordable drinking water receive it as quickly as possible, and that the water systems serving them establish sustainable solutions."

The Drinking Water Needs Assessment — four components

1. Risk Assessment — flags Failing (out of compliance with primary drinking water standards) and At-Risk CWSs, NTNC schools/daycares, state smalls, and domestic wells.
2. Affordability Assessment — uses 1.5% of Median Household Income (%MHI) as the affordability benchmark.
3. Cost Assessment — estimated cost of interim and long-term fixes.
4. Funding Gap Analysis.

Latest figures (2024 Needs Assessment)

• ~400 failing public water systems serving ~812,000 Californians.
• At-risk systems serve roughly 1.49 million.
• ~79% of failing systems serve disadvantaged communities.
• 2025 Needs Assessment fact sheet released; full report follows.

SAFER Clearinghouse

The Clearinghouse is the SWRCB/CPUC-co-developed submission portal that consolidates what used to be siloed drought, conservation, and water-shortage reporting.

• Required reporters: all CWSs, NTNC schools, non-community systems (annual only), and Urban Retail Water Suppliers.
• Default cadence: monthly submission with quarterly deadlines (Apr 30, Jul 31, Oct 31, Jan 31).
• URWS file monthly.
• Systems under drought order can be required to file weekly within 7 days of each week.
• Annual Inventory Report: March 31.

Data captured: water shortage status, source production volumes, supply/demand by customer type, supply augmentation, demand-reduction actions (latter for 500+ connections).

SAFER Dashboard

Public visualization of the Needs Assessment results — the Clearinghouse itself is a submission portal, not a public dashboard (SAFER Dashboard).

flowchart TD
    SB200[SB 200 / 2019
Safe and Affordable
Drinking Water Fund]
    SB200 --> Fund[5% of GHG Reduction Fund
up to $130M/yr
sunset June 30, 2030]
    Fund --> NA[Annual Drinking Water
Needs Assessment]
    NA --> Risk[Risk Assessment
Failing + At-Risk systems]
    NA --> Aff[Affordability Assessment
1.5% MHI burden threshold]
    NA --> Cost[Cost Assessment
Interim + long-term fixes]
    NA --> Gap[Funding Gap Analysis]
    Risk --> FEP[Fund Expenditure Plan
~$855M annually]
    Aff --> FEP
    Cost --> FEP
    Gap --> FEP
    FEP --> Uses[O&M / consolidations
Replacement water
Administrator services]
    NA -.-> Dashboard[Public SAFER Dashboard]

Urban Water Suppliers report monthly potable water production, residential gallons per capita per day (R-GPCD), and conservation activities. Submissions now flow through the SAFER Clearinghouse rather than the legacy standalone Conservation Portal.

Statutory backbone

• SBX7-7 (Water Conservation Act of 2009) — 20×2020 per-capita reduction target.
• "Making Conservation a Way of Life" framework (per AB 1668 / SB 606 and 2023–24 rulemaking) — 55 gpcd indoor residential standard plus outdoor and CII budgets, with monthly URWS reporting feeding compliance tracking.

Public datasets

• "Urban Retail Water Supplier — Water Conservation, Supply, and Demand" on data.ca.gov: monthly production, R-GPCD, supply/demand by source, conservation-action fields. Warning on the page itself: "factors unaccounted for in this dataset can affect per capita water use… not appropriate to use R-GPCD water use data for comparisons across water suppliers" without normalization.
• An archived monthly file covers June 2014 – May 2023.

For a researcher profiling one agency, the workflow typically requires stitching four state datasets plus several federal/local feeds:

Friction points (the MVPi target surface)

• Identifier mismatch: SWRCB uses PWSID (Public Water System ID); DWR uses different IDs for UWMP filers; CPUC uses utility name and district. There is no canonical agency ID across all four.
• Free-text fields: eAR 8A captures rate structures as free text — comparing tier widths or fixed charges across agencies requires regex/manual parsing.
• Self-reporting: every dataset above is self-reported; field-level data quality varies dramatically.
• Cadence misalignment: UWMPs are 5-year, eAR annual, Conservation monthly, allocations updated daily during water year. Joining them requires explicit time-alignment decisions.
• Version drift: the 2020 UWMP XLSX export was last updated in 2024 while the TSV version was last updated in 2023.
• No common schema: each program defines "customer class," "source type," and "supply" slightly differently.

These six friction points are precisely the high-leverage targets for a protocol-design intervention.

flowchart TB
    Agency((Profile a
Single Agency))
    Agency --> A[eAR Section 6
annual production/delivery]
    Agency --> B[eAR Section 8
rates 8A / income 8B / aff 8C]
    Agency --> C[Conservation Portal
SAFER Clearinghouse
monthly R-GPCD]
    Agency --> D[UWMP Data Export
5-yr cycle, 99 TSV tables]
    Agency --> E[SGMA GSP data
basin-level]
    Agency --> F[SAFER Dashboard
risk + affordability classification]
    Agency --> G[CPUC GRC
if investor-owned]
    A -.no canonical ID.-> Friction[Six Friction Points:
1. Identifier mismatch
2. Free-text fields
3. Self-reporting
4. Cadence misalignment
5. Version drift
6. No common schema]
    B -.-> Friction
    C -.-> Friction
    D -.-> Friction
    style Friction fill:#fff3cd
    style Agency fill:#bbdefb

For supply-side analysis beyond what UWMPs report:

• DWR Bulletin 132 — annual statutory report on SWP management, finance, deliveries, Table A allocations.
• USBR CVP allocation announcements — issued February/March, updated through water year (USBR).
• DWR CDEC (California Data Exchange Center) — real-time data on 150+ reservoirs, ~130 SWE snow sensors, river stage/flow, precipitation.
• DWR Water Data Library (WDL) — historical groundwater levels, water quality samples, surface water data.
• CalSim 3 — joint DWR/USBR planning model for SWP/CVP operations (successor to CalSim II).
• NIDIS / U.S. Drought Monitor — weekly drought classification (D0–D4) used by SWP and CVP for shortage triggers.

Prop 218 (1996)

"Right to Vote on Taxes Act." Added Articles XIII C and XIII D to the California Constitution. Water service charges by public agencies are treated as property-related fees under Article XIII D §6.

• Cost-of-service rule: a property-related fee may not exceed the proportional cost of the service attributable to the parcel. Revenue from the fee cannot be used for purposes other than that service.
• Procedural rule (majority protest): mailed notice to every affected parcel owner ≥ 45 days before a public hearing. At/before the hearing's close, if written protests from a majority (50% + 1) of identified parcels are submitted, the agency cannot adopt the increase. One protest per parcel.

Prop 26 (2010)

Tightened the definition of "tax" for state and local levies. Most water/sewer charges remain governed primarily by Prop 218, but Prop 26 has been applied to wholesale water rates (Newhall County Water District v. Castaic Lake Water Agency) — reinforcing that charges must bear a fair/reasonable relationship to the payor's burdens or benefits.

Capistrano (2015)

Capistrano Taxpayers Assn. v. City of San Juan Capistrano, Fourth District Court of Appeal struck down San Juan Capistrano's four-tier conservation rate structure because the city had not attempted to calculate the actual cost of service for each tier. The court preserved tiered rates as constitutional if agencies can demonstrate the marginal cost of service supporting each tier (e.g., higher-cost supplies activated to serve peak/excess use).

LADWP (December 2025)

Court of Appeal upheld LADWP's budget-based tiered rates, finding that source-of-supply cost differentials can justify upper tiers even when supplies are commingled, and that tier breakpoints (allocation widths) do not themselves require cost justification — only the prices (BBK Law alert, December 2025). This decision has materially eased the post-Capistrano rate-design squeeze.

AWWA M1 — the industry methodology

The American Water Works Association M1 Manual: Principles of Water Rates, Fees, and Charges (now in its 7th edition) is the industry-standard cost-of-service methodology. California rate studies routinely cite M1 to document Prop 218 compliance. M1 walks through:

1. Revenue requirement.
2. Cost functionalization (treatment, transmission, distribution, customer service).
3. Allocation to customer classes.
4. Design of rates.

What's out of scope

• Investor-owned utilities (Cal Water, San Jose Water, Cal-Am, Liberty, Suburban, Golden State) — CPUC-regulated, NOT subject to Prop 218.
• Mutual water companies — not public agencies, not subject to Prop 218.

flowchart TD
    Start[Public agency proposes rate change]
    Start --> COS[Cost-of-Service Study
AWWA M1 methodology]
    COS --> Notice[Mail Prop 218 Notice
to every parcel owner
≥45 days before hearing]
    Notice --> Hearing[Public Hearing
accept written protests]
    Hearing --> Count{Majority protest?
50% + 1 of parcels
1 protest per parcel}
    Count -->|Yes| Block[Rate change BLOCKED]
    Count -->|No| Adopt[Board adopts rates]
    Adopt --> Cap{Capistrano test:
Every tier price
cost-justified?}
    Cap -->|No - tiers arbitrary| Lawsuit[Litigation risk
e.g., Capistrano 2015]
    Cap -->|Yes - per AWWA M1| OK[Rates effective
LADWP 2025 confirms
tier widths not required
to be cost-justified]
    style Block fill:#ffcdd2
    style Lawsuit fill:#ffe0b2
    style OK fill:#c8e6c9

A typical California urban water bill has two parts:

• Fixed monthly service charge (regardless of consumption).
• Volumetric (per-CCF or per-HCF) charge (per unit of water used).

1 CCF = 1 HCF = 100 cubic feet = 748 gallons.

Cost structure

Water utilities are unusually fixed-cost-heavy — roughly 60% of total cost of service is fixed (infrastructure, debt service, billing, meter maintenance, treatment standby capacity), with ~40% variable (power, chemicals, wholesale water purchases).

Recovery practice

Despite a 60% fixed cost share, public agencies historically recover a minority of fixed costs through the fixed charge — commonly 25–40% of total revenue — to preserve a strong conservation price signal in the volumetric tiers.

CPUC rules for investor-owned utilities allow recovery of:

• 50% of fixed costs in the service charge for Class A/B (over 10,000 connections).
• 65% for Class C.
• 100% for Class D.

Trade-offs

• Higher fixed share: protects revenue against conservation-driven sales declines (a major problem in 2015 and again in 2022); reflects true cost structure of a capital-intensive utility.
• Higher fixed share: weakens conservation price signal; disproportionately burdens low-volume users (typically smaller and lower-income households).

2024–2026 trend

Post two drought cycles in which volumetric-heavy rate structures left agencies with significant revenue shortfalls, many California agencies are deliberately rebalancing toward higher fixed charges. Examples:

• Shasta Lake: fixed revenue share raised from 46% to 55%.
• Beverly Hills: multi-year fixed-charge step-ups beginning January 2025.
• City of San Diego: +8.7% overall in January 2025.
• MWD wholesale: ~18% rate increase over two years (22% on imported treated water) cascading into retailer rates.

(a) Property tax / ad valorem (1% allocation)

Some special districts (notably MWD of Southern California and several legacy irrigation/water districts) receive a slice of the constitutional 1% general property tax. This pre-dates Prop 13 and is not a "rate" per se but a major fixed revenue stream. Not subject to Prop 218 procedural rules — it's a tax allocation, not a fee.

(b) Parcel charges / standby charges

Flat per-parcel fees, common in agricultural and rural districts and in some urban districts for capital surcharges. Treated as:

• Property-related fees if benefit-based — Prop 218 majority-protest process applies.
• Special taxes if not benefit-based — Prop 218 two-thirds election applies.

(c) Meter / service charge ("ready-to-serve")

The most common fixed charge in urban California. Scaled by meter size using AWWA hydraulic capacity ratios. Standard AWWA equivalent meter units:

Source: AWWA Meter Sizing Table — City of Austin reference.

This methodology has held up under Prop 218 because it ties the charge to the agency's reserved capacity for each parcel — a direct cost-of-service nexus.

Uniform rate

Flat $/CCF regardless of volume. Simple, transparent, low litigation risk under Prop 218, but no conservation signal.

Tiered (inclining block) rate

Most common urban California structure. Higher prices in higher tiers. Post-Capistrano, every tier price must be tied to a cost-of-service rationale — typically marginal cost of incremental supply (recycled, imported, peaking groundwater).

Budget-based (allocation-based) rate

Each customer is assigned an individualized monthly allocation:

• Indoor portion = persons in household × indoor gpcd standard (now 47 gpcd / 1.9 HCF per person per month under the state's efficiency framework).
• Outdoor portion = irrigable landscape area × ETo × plant factor / irrigation efficiency.

Pioneered by Irvine Ranch Water District (IRWD) in 1991; adopted by Las Virgenes MWD, Eastern MWD, Western MWD, Moulton Niguel WD, Santa Margarita WD, Rancho California WD, Laguna Beach CWD, Chino Hills, and LADWP (upheld December 2025).

Documented effects (IRWD case): ~50% per-capita residential reduction; ~8.8% lower single-family demand attributable to BBR structure itself; ~31.5% lower non-residential outdoor demand (IRWD — Budget-Based Rate Structures).

Declining block

Rare in urban California; used in some industrial and agricultural contexts where wholesale economics actually decline with volume.

Drought surcharges

Temporary uplifts triggered by declared shortage stages. Must still be cost-justified under Prop 218 — typically tied to increased cost of replacement supplies or revenue offsets during conservation periods.

flowchart TD
    Bill[California Water Bill]
    Bill --> Fixed[Fixed Charge
~25-40% of revenue]
    Bill --> Var[Variable Charge
~60-75% of revenue]
    Fixed --> PT[Property tax
ad valorem allocation
legacy 1% share]
    Fixed --> Parcel[Parcel / Standby
flat per-parcel]
    Fixed --> Meter[Meter / Service charge
AWWA hydraulic ratio
5/8 = 1.0x, 2 = 8.0x]
    Var --> Uniform[UNIFORM
Flat $/CCF
No conservation signal]
    Var --> Tier[TIERED inclining block
Most common urban CA
Capistrano: per-tier cost basis]
    Var --> Budget[BUDGET-BASED
Individualized allocation
IRWD 1991 pioneer
LADWP 2025 upheld]
    Var --> Decline[DECLINING block
Rare urban; some ag/industrial]
    Var --> Drought[Drought surcharges
Temporary; cost-justified]
    style Budget fill:#c8e6c9
    style Tier fill:#fff9c4

Las Virgenes Municipal Water District (Agoura Hills / Calabasas / Hidden Hills / Westlake Village area; ~70,000–75,000 residents) is the field's most-cited small-agency budget-based-rate operator. Its Water Budgets page provides the cleanest public explanation.

Formula

Indoor budget: ~1.9 HCF (≈1,400 gallons) per resident per month — corresponds to roughly 55 gpcd. Customers must keep their resident count current with the District; variances available for elderly care, hospice, livestock.

Outdoor budget: based on the irrigated landscape area on the parcel, automatically adjusted seasonally by local ETo (longer/hotter days raise the budget; cooler/cloudier periods lower it). Swimming pools are included.

Tier structure: tiered prices apply when usage exceeds budget. LVMWD operates a four-tier potable structure (Indoor / Outdoor-Efficient / Inefficient / Excessive), with per-HCF prices published in the annual rate resolution and the 2025 Rate Study.

Equity and drought arguments

• Customizing budgets by household size and lot landscape area is framed as more equitable than uniform tier widths, which penalize large families on small lots and reward small households on large irrigated lots.
• During drought, the District can tighten outdoor budgets uniformly (e.g., by a percentage) rather than imposing crude across-the-board cutbacks — preserving the indoor allocation that meets essential needs.
• High-tier penalty pricing falls only on customers who exceed their personalized budget — the price signal is targeted at discretionary outdoor over-use rather than at all volumetric users.

The IRWD outdoor formula

Outdoor budget (HCF) = Landscape area (acres) × ETo (inches) × 0.75 ET adjustment (plant factor × irrigation efficiency) × unit conversion.

The 0.75 ET adjustment combines a plant factor (typically 0.5–0.7 for residential) and an irrigation efficiency (typically 0.7–0.8) — set by the agency in the rate ordinance.

flowchart LR
    subgraph Inputs["CUSTOMER INPUTS"]
        R[Number of residents]
        LA[Landscape area sq ft]
        Z[ZIP code → local ETo]
    end
    subgraph Formula["BUDGET FORMULA"]
        IB[Indoor budget
= residents × 1.9 HCF
≈ 47 gpcd state standard]
        OB[Outdoor budget
= area × ETo × 0.75
plant factor × irrig efficiency]
        Total[Monthly Water Budget HCF]
    end
    subgraph Pricing["TIERED PRICING"]
        T1[Tier 1 Indoor
cheapest $/HCF]
        T2[Tier 2 Efficient outdoor]
        T3[Tier 3 Inefficient
steep penalty]
        T4[Tier 4 Excessive
highest penalty]
    end
    R --> IB
    LA --> OB
    Z --> OB
    IB --> Total
    OB --> Total
    Total --> T1
    Total --> T2
    Total --> T3
    Total --> T4

Existing federal/state programs (mostly expired)

• CWWAPP (California Water and Wastewater Arrearages Payment Program): $985M federal pandemic-era program for unpaid water bills (March 2020–June 2021).
• Extended CWWAPP: added $600M for arrears through Dec 31, 2022; final disbursements May 2024. Not income-based — funds applied to eligible delinquent accounts directly.
• LIHWAP (Low-Income Household Water Assistance Program): income-based, federally funded, up to $1,000/household.

SB 222 (Dodd, 2021–22)

Would have created a permanent statewide Low-Income Water Rate Assistance Program. Vetoed September 28, 2022 by Governor Newsom on funding grounds. Subsequent affordability proposals continue under the State Water Board's Affordability framework (Bill text; BBK veto analysis).

AB 2180 (Ward, 2026)

Introduced February 2026 to clarify Prop 218 rate-setting rules — an active legislative response to the post-Capistrano environment.

The unresolved equity gap

Budget-based rates address the household-size equity problem (large families on small lots not penalized) but do not solve affordability for low-income customers. That requires a separate income-tested subsidy, which California still lacks at the statewide level after SB 222's veto. The 2024–2026 fixed-charge rebalancing trend is a pragmatic response to drought revenue volatility, but it shifts cost burden toward smaller users and amplifies the affordability gap.

• Legal form: Special district under the Metropolitan Water District Act of 1928 (state-chartered regional wholesaler — not a JPA).
• Service area / population: ~5,200 sq mi across six SoCal counties; ~19 million people; 26 member agencies.
• Governance: 38-member board representing 14 cities, 11 municipal water districts, 1 county water authority (SDCWA). Representation weighted by historic assessed valuation.
• Supply portfolio: SWP Table A ~1.911 MAF/yr + Colorado River (~550 KAF priority + transfers up to ~1.2 MAF) + storage banking (Diamond Valley Lake, Lake Mead ICS, Semitropic).
• Rate stack: volumetric supply rate (Tier 1/Tier 2 discontinued for CY 2025/26 as the 2014 Purchase Order agreements expired); Readiness-to-Serve (RTS) Charge; Capacity Charge; Supply Reliability; Customer Service; Emergency Storage; Infrastructure Access; historic ad valorem property tax (now capped).
• Distinctive: Wholesaler-of-wholesalers. MWD's rate is a pass-through in nearly every SoCal retail rate. The Tier 1/Tier 2 discontinuation in 2025 is a significant rate-structure shift after a decade of supply-purchase orders.

• Legal form: Department of the City of Los Angeles (created 1902); largest municipal utility in the U.S.
• Governance: 5-member Board of Water and Power Commissioners appointed by the Mayor, confirmed by City Council.
• Service area / population: ~4 million in the City of Los Angeles.
• Supply portfolio: LA Aqueduct (Owens Valley / Mono Basin) — historically ~half of total, now closer to a third due to environmental obligations; MWD purchases; local groundwater (San Fernando, Sylmar, Central Basins); recycled water expanding rapidly under Operation NEXT (target 100% wastewater recycling).
• Rate structure: Four-tier inclining block for residential; two tiers for commercial. Tier 1 sized to essential indoor needs; Tier allotments include adjusted shortage-year (ASY) logic — Tier 1 multi-family/commercial allotments are pegged to historical lows (FY07-09 or Dec-2014/Mar-2015 drought baselines).
• Distinctive: Vertically integrated city department; integrated power/water cross-subsidies; major recycled-water buildout. Budget-based-tier rates upheld by Court of Appeal in December 2025 — a landmark Prop 218 ruling.

• Legal form: California Water District under Water Code §34000 (special district), formed 1961. Notably, despite Water Code §34000 districts being a primarily-agricultural legal form with landowner-weighted voting, IRWD evolved into the canonical urban budget-based-rate provider.
• Service area: ~181 sq mi (Irvine + parts of Costa Mesa, Lake Forest, Newport Beach, Orange, Tustin, unincorporated OC); ~425,000 residents plus daytime population ~640,000; ~250,000 service connections.
• Supply portfolio: MWD imports (via MWDOC), local groundwater (Orange County Basin via OCWD), and one of California's largest recycled water ("purple pipe") systems — ~28% of total demand met by recycled.
• Rate structure: Pioneer of budget-based tiered rates since 1991. Individualized monthly allocation; sharp upper-tier penalties for use above budget.
• Distinctive: National template for budget-based rates and dual-distribution recycled water. The reference case for nearly every other agency's BBR adoption.

• Legal form: Municipal utility district under the Municipal Utility District Act (Water Code §71000+), formed 1923.
• Service area / population: 332 sq mi across Alameda and Contra Costa Counties; ~1.4 million water customers; ~685,000 wastewater.
• Supply portfolio: ~90%+ from the Mokelumne River via Pardee and Camanche reservoirs and a 90-mile aqueduct; supplemental Sacramento River water via the 1970 Freeport Regional Water Project agreement (CVP exchange) during drought; local watershed storage.
• Rate structure: Three-tier inclining block for single-family residential. FY26: Tier 1 first 7 Ccf/month (≤172 gpd), Tier 2 to 16 Ccf/month at $9.15/Ccf, Tier 3 above 16 Ccf at $10.79/Ccf. Plus elected fixed service charges and a drought surcharge mechanism.
• Distinctive: NorCal counterpart to MWD scale; elected board; long-running negotiations over Mokelumne flow obligations to fish.

• Legal form: County water authority / JPA-style wholesaler under the County Water Authority Act (1944).
• Service area / population: ~3.3 million people; 22 member agencies (cities, water districts, irrigation districts, military, federally-recognized tribe).
• Supply portfolio: QSA-transferred water from IID (up to 200,000 AF/yr through 2047); All-American and Coachella Canal lining transfers (~80,000 AF/yr); Carlsbad Desalination Plant (Poseidon, online December 2015, up to 56,000 AF/yr — largest seawater desal in the Western Hemisphere); MWD imports (now a smaller share after years of diversification); local surface and recycled.
• Rate structure: Two-tier wholesale to member agencies plus a Customer Service Charge, Storage Charge, and Supply Reliability Charge.
• Distinctive: The QSA-era "diversify away from MWD" model. Long-running rate litigation with MWD over SWP costs allocated to transported (wheeled) IID water. In 2026 the Authority approved an MOU exploring an interstate transfer of Carlsbad desal water to other Lower Basin states.

• Legal form: Municipal water district under Water Code §71000+.
• Service area / population: 122 sq mi in western LA County (Agoura Hills, Calabasas, Hidden Hills, Westlake Village, adjacent unincorporated); ~70,000–75,000 residents.
• Supply portfolio: 100% imported water from MWD (no usable local groundwater). Recycled water for non-potable irrigation.
• Rate structure: Pure budget-based rates — individualized allocation; sharp upper-tier penalties; pass-through of MWD rate changes.
• Distinctive: The "poster child" small budget-based-rate agency. Experienced extreme rate-tier exposure during 2022 MWD allocations under EO-declared shortages.

• Legal form: Independent special district — specifically a County Water District established by an act of the California Legislature on January 9, 1918. Predates most general special-district enabling statutes. Governed by a 5-member elected board.
• Service area: ~1,000 sq mi from the San Gorgonio Pass to the Salton Sea, primarily in Riverside County.
• Service lines: domestic (potable) water, agricultural irrigation, recycled/non-potable, sanitation/wastewater, stormwater, groundwater replenishment, regional water management.
• Supply sources: 1. Groundwater from the Coachella Valley Groundwater Basin — largest source for domestic delivery. 2. Colorado River water via the 123-mile Coachella Branch of the All-American Canal. Federal contracted entitlement up to ~459,000 AF/yr (post-QSA quantified right 450,000 AF; 432,850 AF under 2022 schedule). Primarily agricultural (~260,000 AF to ~76,350 acres). 3. State Water Project water via an exchange with MWD — CVWD's SWP Table A allocation is delivered as Colorado River water through MWD's Whitewater turnouts, then used to replenish the West Coachella Valley aquifer at the Whitewater River Groundwater Replenishment Facility. 4. Recycled water for golf courses and large landscapes.
• Groundwater replenishment: Thomas E. Levy GWR Facility (East Valley) ~40,000 AF/yr capacity; Whitewater (West Valley) historically several hundred thousand AF/yr.
• 2020 UWMP: prepared regionally with five other Coachella Valley suppliers (Coachella Water Authority, Desert Water Agency, Indio Water Authority, Mission Springs Water District, Myoma Dunes Mutual Water Co.). Adopted June 22, 2021.
• Rate structure: domestic water uses tiered, water-budget-based rates with Tier 1 (indoor essential), Tier 2 (efficient outdoor), Tier 3 (excessive). 5% overall rate increase effective July 1, 2025.
• Distinctive: One of the largest and oldest county water districts. Resource model is groundwater-centric for potable, surface-water-centric for ag — and uses imports as recharge rather than direct delivery.

• Legal form: Investor-owned utility; subsidiary of California Water Service Group (NYSE: CWT). Regulated by CPUC.
• Service area / population: ~2 million people in California across ~24 district systems (Bakersfield, Chico, East LA, Hermosa-Redondo, Livermore, Los Altos, Marysville, Salinas, Stockton, Visalia, Westlake, etc.). CWT group serves 2.2M+ across CA, HI, NM, WA, TX.
• GRC cycle: Cal Water files a General Rate Case (GRC) every 3 years with the CPUC. Most recent decision (April 30, 2026) on the 2024 GRC authorized $1.45B in district capital investments and revenue increases of $90.5M in 2026 (+10.9%), $43.2M in 2027 (+4.7%), $48.9M in 2028 (+5.1%), effective July 1, 2026 (Cal Water Group GRC announcement).
• Distinctive: Unlike a public agency (Prop 218 process), Cal Water rates are set through quasi-judicial CPUC proceedings with Public Advocates Office intervenor review. Capital recovery is more predictable but more litigated.

Most California "mutuals" are nonprofit mutual benefit corporations owned by their shareholders/customers. CalMutuals counts ~582 active mutuals statewide.

Typical structure: shareholders elect a board, which typically retains a third-party management company and water-law counsel; rates are set internally (mutuals are not subject to Prop 218 since they are not public agencies, nor to CPUC GRC oversight).

Example — Rossmoor Mutual (Walnut Creek; serves the Rossmoor 55+ community of ~9,500 units) — shareholder-owned mutual corporation purchasing wholesale supply from EBMUD and reselling internally to members.

Many mutuals serve small developments of a few hundred to a few thousand connections and have very thin technical staff — which is why mutuals are over-represented among SAFER "failing" and "at-risk" systems.

Chapter 1 — Introduction

Identifies the supplier and lists its UWMP filing history. Read for: agency name, contact, signatory date, whether the plan is individual or regional.

Chapter 2 — Plan Preparation

Lists coordinated agencies (wholesalers, member retailers, GSAs). Read for: who is upstream of this supplier.

Chapter 3 — System Description

Service area, climate, population history and projection (to 2045). Read for: per-capita projection assumptions — these are often optimistic and worth challenging.

Chapter 4 — System Water Use

Historical demand by customer class (single-family residential, multi-family, commercial, industrial, institutional, landscape). Projected demand to 2045 in 5-year increments. Read for: large CII demand, the recycled water share, and whether projected per-capita use squares with state objectives.

Chapter 5 — SB X7-7 Baseline & Targets / Urban Water Use Objectives

Compliance with the 20×2020 framework (in the 2020 cycle) and prep for SB 606/AB 1668 (Making Conservation a Way of Life). Read for: baseline year, target, actual 2020 compliance, and any variance requests.

Chapter 6 — Supply Characterization

The heart of the document. Lists each supply source with current and projected volumes to 2045. Read for: imported supply assumptions (do they match MWD/CVP/SWP assumptions?), recycled buildout schedule, groundwater pumping vs. SGMA sustainable yield.

Chapter 7 — Water Service Reliability and Drought Risk Assessment

Three reliability tables: normal year, single-dry year, multi-dry year (5 consecutive). Plus the 5-year DRA. Read for: whether any year shows a supply-demand gap, the DRA methodology (deterministic worst-case vs. probabilistic), and the assumed climate-change adjustments.

Chapter 8 — Water Shortage Contingency Plan

Six standard shortage levels, response actions, communication protocols, legal authority, financial impact. Read for: whether financial impact analysis includes a rate-stabilization fund discussion.

Chapter 9 — Demand Management Measures

Conservation programs narrative. Read for: rebates offered, AMI deployment, audit programs, MWELO ordinance compliance.

Chapter 10 — Plan Adoption, Submittal, Implementation

Public hearing date, board adoption resolution, submittal date to DWR. Read for: completeness determination from DWR.

Appendices

DMM evidence, water-loss audit, technical memos. The water-loss audit (per SB 555) is the single most useful data quality artifact in the appendices.