01
About the Utility
The San Diego County Water Authority is the wholesale water supplier for San Diego County. It delivers supplies to 22 retail water providers, including cities, special districts and a military base, which together serve 3.3 million residents. Its Board sets wholesale rates and adopts budgets combining operating and capital spending across water supply, water facilities and business services. Membership has been contested: in December 2023 the Authority let Rainbow Municipal Water District and Fallbrook Public Utility District detach for an immediate $25 million payment, and state ratepayer-protection legislation took effect in January 2024. Relations with the Metropolitan Water District of Southern California combine paid conveyance with rate litigation.
02
Water System
Conserved Colorado River water from the Imperial Valley, secured under the 2003 Quantification Settlement Agreement, provides over half of the region's water. That supply depends on the Metropolitan Water District, which the Authority pays to carry it through the Colorado River Aqueduct; an extended Exchange Agreement secures 2 million acre-feet of conserved water for delivery between 2037 and 2047. Seawater desalination adds a local source: the Poseidon Water-owned Carlsbad plant supplies up to 56,000 acre-feet a year under a long-term purchase agreement. Total demand across the service area was approximately 469,000 acre-feet in fiscal 2025, mostly municipal and industrial.
Service-area water use
Reported actuals, fiscal years 2016–2025 (years to 30 June)
All ten values are reported actuals from one historical water-use table on one basis: total use across the Water Authority service area, not the Authority's own wholesale supplies.
Sources: San Diego County Water Authority, 2025 Urban Water Management Plan (June 2026), Table 2-1.03
Infrastructure & Performance
The regional delivery system comprises 308 miles of large-diameter pipelines, 1,600 aqueduct-related structures and approximately 100 metering and flow control facilities, alongside a treatment plant, hydroelectric facilities, pump stations and a dam. The Twin Oaks Valley Water Treatment Plant treats up to 100 million gallons daily. Under a formal asset management programme, the Authority has relined 50 miles of its PCCP pipelines and rehabilitated five flow control facilities. Volumes moving through the system have contracted markedly over the past decade.
04
Investment & Priorities
Water purchases and treatment, debt service and infrastructure projects drive 91% of the Authority's costs. Wholesale rates rose by a total of 14% for 2025, with passthrough costs accounting for 11%, before the Board approved a 3% increase for 2027. Audited long-term debt outstanding has declined in each year since fiscal 2022. The Authority calls its Capital Improvement Program the cornerstone of keeping delivery and treatment systems meeting changing demands. Credit standing has weakened, with S&P cutting its senior-lien rating two notches.
05
Sustainability & Resilience
Storage anchors drought resilience. The Authority owns approximately two-thirds of San Vicente Reservoir's storage capacity and had approximately 100,000 acre-feet available in emergency and carryover storage at the end of August 2023. Its latest Urban Water Management Plan projects normal-year supply surpluses in 2030 and 2050. On climate, the Authority reports meeting its state-aligned greenhouse gas reduction target, and its Rancho Peñasquitos hydroelectric facility generates renewable energy. A proposed pumped-storage facility at San Vicente would add large-scale energy storage if approved and built.
06
Key Challenges
- Securing Colorado River deliveries that depend on MWD's aqueduct and an Exchange Agreement running to 2047.
- Financing debt service and capital renewal as supply volumes fall and S&P lowers its senior-lien rating.
- Containing wholesale rate increases for 22 retail providers after a 14% total rise for 2025.
- Protecting remaining ratepayers after Rainbow and Fallbrook's detachment from the Authority.
07
Major Projects
Carlsbad Desalination Plant supply
Poseidon Water-owned seawater desalination plant supplying the Authority under a 30-year Water Purchase Agreement.
- Status / period
- Delivering water since December 2015
- Investment / capacity
- Up to 56,000 acre-feet a year · $1 billion project
San Vicente Energy Storage Facility
Proposed pumped-storage project at San Vicente Reservoir, evaluated jointly with the City of San Diego.
- Status / period
- Proposed; online in the early 2030s if approved and built
- Investment / capacity
- 500 MW for eight hours · $18 million state support
Regional conveyance system study
Assesses pipe and tunnel alignments that would carry Imperial Valley supplies from Imperial Dam to San Vicente Reservoir.
- Status / period
- Under study
- Investment / capacity
- Alternative to conveyance through the Colorado River Aqueduct