Briones Reservior - Contra Costa County, California

Visited on 3/10/2019, Jeff and I took a drive with our pups, Summer and Skye to the San Francisco Bay Area to take a tour of all of the lakes in Contra Costa County and a couple in Alameda County.  After visiting San Pablo Reservoir, we drove to the top of the ridge to the north and found Briones Reservoir.  This reservoir is located at 576 feet above sea level and is 735 surface acres in size.  

Briones Reservoir is an open cut terminal water storage reservoir located in western Contra Costa County, in the East Bay region of the San Francisco Bay Area, California. It is owned and operated by the East Bay Municipal Utility District (EBMUD).  The reservoir is in the Briones Hills, on the west side of Briones Regional Park and northeast of Orinda. It is impounded by Briones Dam, an earthen dam completed in 1964. The reservoir is the largest of EBMUD’s five East Bay terminal reservoirs.  The Briones Reservoir has two sources for its water, one local and one imported.  Its watershed includes the Bear Creek drainage. Bear Creek formerly flowed down the valley, which the reservoir partially submerges, and still enters from the eastern section.

The major water source into the Briones Reservoir is imported from the Briones Diversion Works near Orinda. It is delivered through the Briones Aqueduct, a 7-foot, 6-inch steel pipe, operated by four pumps that can deliver up to 60 million gallons a day.   This is water imported from EDMUD’s biggest water source, the Mokelumne River in the San Joaquin Valley.

Water then leaves Briones Reservoir and flows to the lower part of the valley and into San Pablo Reservoir. From there, the water is distributed by a pumping plant in Kensington.

Because the water in the reservoir is mainly for human potable water uses, EBMUD is very strict about recreational activities. Fishing, swimming, and wading are not allowed. However, college rowing teams from Mills College, UC Berkeley and Saint Mary's College have permission to use the lake under certain rules, such as the inspection of all boats before use on the lake in order to prevent contamination.

I hiked down to the water edge and had a nice conversation with a group of hikers, the Reeves, a local couple from the Bay Area and his parents visiting from Tucson, Arizona. 

Trail down from the parking lot down to the water edge.