The lake received its name from the stream which is its source, Temescal Creek, which was dammed in 1868 to create a reservoir to provide drinking water for the greater East Bay area, pumped by the Contra Costa Water Company, owned by Anthony Chabot. Prior to being dammed, Lake Temescal was a sag pond, a depression caused by the Hayward Fault. The bulk of the manual labor of removing soil and digging to bedrock was provided by Chinese immigrants, who probably immigrated to build the railroads. Herds of wild mustangs were used to compact the tons of dirt that were brought to create the dam. The dam is long and wide and rises above the creek.