Diablo Water District (District) is an independent, self-governing local public agency created on May 7, 1953, under the County Water District Law of California. The District is governed by an elected five-member Board of Directors.

The District, with a staff of 25 employees, obtains, treats, and supplies water for about 45,000 people and the parks, schools, and businesses throughout a 21-square-mile area consisting of Oakley, Cypress Corridor, and Hotchkiss Tract, as well as Summer Lakes, and portions of Bethel Island and Knightsen.

The District was formed in 1953 as the Oakley Water District. The District is bounded by the San Joaquin River to the north, the City of Antioch to the west, the City of Brentwood to the south, and unincorporated area to the east. In 2017, the District became the Groundwater Sustainability Agency for its service area to ensure the long-term sustainability of the groundwater basin.

The District’s current Sphere of Influence (SOI) encompasses an additional 3.5 square miles and includes area adjacent to the District’s southern and eastern boundaries and the Veale Tract to the southeast. The District primarily supplies treated water for domestic use and some non-potable water for park and landscape irrigation. The District’s sources of water supply are untreated water from the Central Valley Project (CVP) purchased from the Contra Costa Water District (CCWD) and groundwater extracted from the San Joaquin Valley Basin. The surface water is conveyed through the Contra Costa Canal and treated at the Randall-Bold Water Treatment Plant (RBWTP) in Oakley. The RBWTP is jointly owned by DWD and CCWD. The plant is managed and operated by CCWD.