The GWRS meets the need

Two-thirds of California's population lives in Southern California where less than one-third of the State’s precipitation falls. While other Southern California counties rely mostly on imported water supplies to meet their water needs, Orange County does not. A large percentage of its water supply is derived from a large groundwater basin. 

The Orange County Groundwater Basin underlies north and central Orange County. Extending from the Pacific Ocean to Yorba Linda, it holds over 40 million acre-feet (AF), (49 billion cubic meters) of water, the annual yield of the basin is nearly 300,000 AF (370 million cubic meters) of water and an operational capacity of roughly 500,000 AF (860 million cubic meters).

Since its establishment in 1933, OCWD has been monitoring groundwater levels in the basin. In the 1940s, its role shifted. Natural recharge could no longer offset groundwater extraction. As a result, OCWD launched a groundwater replenishment program. Monitoring efforts were soon accompanied by active management of groundwater levels in order to protect the basin.

Southern California's water supply challenges

Historically, the main source of water for basin replenishment had been the Santa Ana River. Flowing west from the San Bernardino Mountains, the river winds through San Bernardino and Riverside counties before reaching Orange County. At upstream locations water conservation and recycling occur. Between these activities and periodic drier weather patterns, water flows fluctuate from year to year.

To compensate for these fluctuations in replenishment water, OCWD began importing water from other sources, first the Colorado River and later, the Sacramento-San Joaquin River Delta. Approximately 25% of the water supplied to north and central Orange County is derived from these sources. Still, relying on these distant watersheds to quench our thirst and recharge groundwater poses several challenges. Importing water from distant sources is energy-intensive and expensive. Further, the Delta is an environmentally sensitive area that is home to water-dependent threatened and endangered species.

Water rights to the Colorado River are shared among seven states and Mexico, each facing population growth and reduced precipitation. At a time when our thirst is increasing, the river’s flow is decreasing. 

GWRS – water you can count on

North and central Orange County's future depends on reliable water supplies. The GWRS provides the region with water it can count on and serves as a model project for other regions throughout the United States and the world that are, or will be, facing natural and man-made water supply challenges.