Lake Chabot is a man-made lake covering 317 acres (1.3 km2) in Alameda County, California, United States. Part of the lake lies within Oakland city limits, but most of it lies in unincorporated Castro Valley, just east of San Leandro. It was formed by the damming of San Leandro Creek. The lake was completed in 1875 to serve as a primary source of water for the East Bay.