Sixty years ago the average customer agency in West Basin's service area relied completely on groundwater. Today, however, it relies on a more diverse mix of water resources: 21% groundwater, 65% imported water, 7% recycled water and 7% conservation efforts. Diversification of our water supply has become West Basin's answer to ensuring a reliable supply of water for our service area. Traditional use of imported water will continue to decrease with the expansion of alternative sources such as recycled water, conservation, and ocean-water desalination.
The groundwater supply is extracted from the West Coast Groundwater Basin that underlies much of the West Basin service area. The average amount of water extracted from the West Coast Groundwater Basin by our customer agencies is approximately 36,000 acre-feet per year. Because the West Coast Groundwater Basin is adjudicated (ie. the amount to be extracted each year has been determined by a court decision), the rights to the amount of groundwater extracted each year remain virtually the same. Total adjudicated pumping rights in the West Coast Groundwater Basin remain at approximately 55,000 acre-feet per year.
The entity responsible for maintaining and replenishing the West Coast Groundwater Basin is the Water Replenishment District of Southern California (WRD). They replenish the basin with a mix of imported water and recycled water. They are also responsible for protecting the groundwater basin from seawater intrusion. WRD injects high-purity, recycled water from West Basin’s water recycling facility into the West Coast Seawater Barrier.