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 Briones Reservoir has two sources for its water, one local and one imported.

Bear Creek formerly flowed down the valley, which the reservoir partially submerges, and still enters from the eastern section.

The trailhead is at the Bear Creek Staging Area, which is within Briones Regional Park.