Orange County Water District

About the Utility

Orange County Water District was formed by the California State Legislature to manage the Orange County Groundwater Basin. It is a basin manager rather than a retail supplier: retail water agencies pump groundwater from producer wells, while the District replenishes and protects the aquifers. It describes the basin as supplying 85% of the water used by 2.5 million people in northern Orange County. Its Board sets a Basin Production Percentage to govern pumping and a Replenishment Assessment per acre-foot; revenues derive primarily from these assessments and property taxes. Its purification plant relies on secondary treated wastewater supplied by Orange County Sanitation District.

Water System

The basin is replenished with Santa Ana River flows, purified recycled water and imported water from the Metropolitan Water District of Southern California. In the water year to June 2025 the District replenished 252,200 acre-feet, while groundwater production reached 302,214 acre-feet and total service-area demands were 379,370 acre-feet. Rainfall over the basin was thirty-seven percent of the long-term average, and the accumulated overdraft rose to 183,000 acre-feet. Storage is managed within a defined operating range below full, and most pumping comes from large system production wells.

Infrastructure & Performance

The Groundwater Replenishment System is the District's central asset. It purifies treated wastewater through microfiltration, reverse osmosis and ultraviolet light with hydrogen peroxide, and its design production capacity is 130 MGD. In calendar 2025 it produced approximately 118,746 acre-feet, operated in compliance with its permit throughout the year and made no emergency discharges to the Santa Ana River. Nearly 15% of that output was injected at the Talbert Barrier, a line of injection wells that holds back seawater along the coast, and approximately 79% was recharged at the Forebay basins.

Investment & Priorities

Capital spending centres on supply and water-quality assets. The Groundwater Replenishment System, including all expansions, has cost more than $900 million to build. The proposed FY 2026-27 budget funds a Capital Improvement Program and payments for PFAS treatment at producers' wells, shown below as budgets rather than outturns, and raises the Replenishment Assessment to $728 per acre-foot. Total long-term debt was $798,019,191 at the end of FY2025, below the prior year, and the District's bonds are rated AAA by S&P and Fitch and Aa1 by Moody's.

Sustainability & Resilience

PFAS contamination is the most immediate resilience pressure. Pumping fell in FY2022 and FY2023 as producer wells were taken out of service for exceeding the state PFOA and PFOS response level. The District has since restored 49 groundwater wells with ion-exchange treatment and is planning, designing or constructing systems for 57 more, supported by settlements with 3M and DuPont, a low-interest federal WIFIA loan and grants. Purified recycled water uses one-third the energy required to desalinate seawater.

Key Challenges

1. Treating PFAS-affected wells within a programme projected to cost $1.8 billion over 30 years.
2. Reducing an accumulated basin overdraft that reached 183,000 acre-feet.
3. Maintaining purified water production and permit compliance at full-expansion scale.
4. Protecting the coastal aquifer from seawater intrusion at the Talbert Barrier.
5. Financing capital renewal as the Replenishment Assessment rises to $728 per acre-foot.

Major Projects