The Los Vaqueros Reservoir in Contra Costa County, Calif., on Wednesday, February 10, 2010, located in the northern Diablo Range, within northeastern Contra Costa County in northern Calif. Completed by the Contra Costa Water District (CCWD) in 1998, the reservoir was built to improve the quality of drinking water for its 550,000 customers in Central and Eastern Contra Costa County. The reservoir is accessible via Vasco Road, which connects Brentwood and Livermore. (Dale Kolke/California Department of Water Resources via Bay City News)