The Contra Costa County Board of Supervisors on Tuesday voted 5-0 during a closed session to file a petition challenging the California Department of Water Resources’ final environmental impact report for the Delta Conveyance Project once the state certifies it. The decision follows the Dec. 8 release of the report for the controversial $16 billion water project that would build a tunnel and two intakes to pull water from the Delta and connect it to the Bethany Reservoir on the California Aqueduct before delivering it to homes and farms in Central and Southern California. In a separate action, Supervisor Ken Carlson, on behalf of the county, signed onto a letter from the Delta Counties Coalition — addressed to DWR Director Karla Nemeth — to request at least 60 days of public review of the final EIR.