The Source of Your Water

Your Water Source

The primary source of water for 500,000 residents of the Contra Costa Water District in central and eastern Contra Costa County is the Sacramento-San Joaquin Delta. Originating from rivers within the Sierra, the water flows into the Sacramento and San Joaquin rivers, eventually finding its way into the Delta.

We draw water from Rock Slough near Oakley, Mallard Slough in Bay Point, Old River near the town of Discovery Bay and nearby Middle River. We divert water under our federal Central Valley Project contract as well as our own water rights and agreements with neighboring agencies.

The water is transported in the 48-mile Contra Costa Canal, which startsSacramento-San Joaquin Delta Map Opens in new window at Rock Slough, then stretches west to Clyde, south to Walnut Creek and north to Martinez.

We can also store water Los Vaqueros Reservoir south of Brentwood, Contra Loma Reservoir in Antioch, the Mallard Reservoir in Concord and the Martinez Reservoir in Martinez.

Providing to Communities

We treat water and provide it to about 250,000 residents in Brentwood, Clayton, Clyde, Concord, Pacheco, Port Costa, Bay Point, and parts of Pleasant Hill, Martinez and Walnut Creek. See our Service Area Map.

We also sell untreated water (raw water) from the canal to the cities of Antioch, Martinez and Pittsburg, and the Diablo Water District (Oakley). These five agencies treat, distribute and bill for the water themselves, serving 250,000 people.

Most of these agencies can also draw groundwater from wells or surface water from their own reservoirs or the Sacramento or San Joaquin rivers as supplemental supplies.

Water Supply Planning

The District develops comprehensive, long-term planning documents to manage our water supply and ensure we meet current and future demands. Learn more about water supply planning.