Seawater Barrier

The threat of salt water from the ocean contaminating Orange County's groundwater basin has been a concern for decades. The groundwater basin is the county's primary potable water supply and provides storage for nearly 500,000 acre-feet (616,000 cubic meters) of usable water. As the region has continued to grow, water demands have risen. Pumping more water out of the basin increases the possibility of salt water seeping into the basin.

The Orange County Water District (OCWD) built Water Factory 21 (WF-21) in the mid-1970s to treat wastewater to inject into 23 wells along the coast, creating a seawater intrusion barrier. As demands to pump more water out of the basin increased, the barrier required more purified water than WF-21 could produce, which had a daily production of 22.6 million gallons (85,600 cubic meters) per day. (14 million gallons (53,000 cubic meters) of WF-21 water blended with 8.6 million gallons (32,600 cubic meters) of deep well water.)

With the completion of the GWRS, OCWD now produces enough water to form a highly protective barrier that safeguards Orange County's fresh water supply. About half of the water produced by GWRS (35 million gallons; 132,000 cubic meters) is injected into the seawater intrusion barrier every day.