Groundwater management

Orange County Water District is responsible for managing the vast groundwater basin that provides most of northern and central Orange County’s drinking water. As part of its groundwater management program, OCWD maintains a diversified water supply portfolio to ensure a variety of water sources fill the basin. OCWD’s long history of active management and investment in the local groundwater basin has not only sustained the basin but tripled its annual sustainable yield.

To maintain a healthy basin, OCWD will continue to explore all water supply options, including desalination, cloud seeding, enhanced water reuse, increased stormwater capture, storage partnerships, and more.

160+ billion

gallons stored in the basin

85%

drinking water supply for 19 retailers

2.5 million

people served in north and central OC

30

recharge basins that store and percolate water into the basin

400

District-owned monitoring wells throughout the basin
View Today’s Water Supply

Sources of Water in the Basin:

  • Santa Ana River
  • Stormwater
  • Natural recharge such as rainfall
  • Imported water from northern California and the Colorado River
  • Recycled water from the Groundwater Replenishment System (GWRS)

Recharging the Groundwater Basin

OCWD maintains one of the world’s most advanced aquifer recharge systems to replace the water that is pumped from wells belonging to local water agencies, cities and other groundwater users.

The District has purchased nearly 1,600 acres to maximize the capture and recharge of available water supplies. More than two dozen percolation basins slowly put water back into the basin while naturally filtering and purifying it.

The District manages a six-mile stretch of the Santa Ana River. “T” and “L” levees are constructed in the river to channel flow up, down, and cross stream to increase percolation. The T and L levees also provide nesting and roosting habitat for numerous types of waterfowl. Inflatable rubber dams, levees and valves divert the water to recharge facilities.

The Prado Wetlands, the largest constructed wetlands on the west coast of the U.S., are designed to remove nitrogen and other chemicals from the Santa Ana River before the water flows downstream into Orange County where it is eventually recharged into the basin.

Protecting Water Quality

OCWD’s Philip L. Anthony Water Quality Laboratory administers a comprehensive groundwater and surface water monitoring program to continually generate real-time data on local water supply and ensure the water meets all state and federal drinking water regulations.

More than 400 monitoring wells are located throughout the basin where samples are collected and tested. The District tests for more than 500 compounds from approximately 1,500 locations throughout the basin, analyzes more than 20,000 samples each year and reports more than 400,000 results.

OCWD currently operates two seawater intrusion barriers, known as the Talbert Barrier (located in the cities of Huntington Beach and Fountain Valley) and the Alamitos Barrier (located in Seal Beach and Long Beach along the Los Angeles-Orange County border). Additionally, the District has been investigating the nature and extent of seawater intrusion in the Sunset Gap area beneath the Naval Weapons Station in Seal Beach to determine the need for a potential future barrier.

From emerging issues such as per- and polyfluoroalkyl substances (PFAS) to ongoing groundwater cleanup efforts in the northern and southern parts of the basin, the District remains committed to solve threats to groundwater.

Increasing Local Water Supplies

OCWD is committed to securing long-term water reliability through the development of local water supplies and investments in water infrastructure. Examples include:

The Groundwater Replenishment System (GWRS) produces 130 million gallons of high-quality drinking water every day, enough to serve 1 million people. The facility recycles 100% of OC San’s reclaimable flows, maximizing the District’s water reuse efforts.  

OCWD works with the U.S. Army Corps of Engineers to store millions of gallons of water behind Prado Dam in Corona. This water is eventually released at rates that the District can capture and recharge into the basin. Initiatives like Forecast Informed Reservoir Operations (FIRO), a strategy that uses advanced atmospheric river forecasting and modeling tools to make real-time decisions about reservoir operations, allows OCWD to capture more local stormwater and increase the region’s drinking water supply.

The Santa Ana River Conservation and Conjunctive Use Program (SARCCUP) is a collaborative, watershed-scale approach toward groundwater basin management, replenishment, and water transfers. This project will use up to 137,000 acre-feet of storage in six groundwater basins, resulting in regional benefits for millions of customers.

Click on the links below for more information.