Niles Canyon Aqueduct/Secret Sidewalk (Fremont)

The aqueduct was built by the Spring Valley Water Company during the first decade of the 20th century in order to serve the water needs of San Franciscans. At one time, San Francisco received over half of its water supply through this aqueduct. The water flow was combined in Sunol, on the spot where the Sunol Water Temple stands, from water coming from Arroyo de la Laguna, Alameda Creek, Sunol, and artesian wells in Pleasanton. Among locals, it is referred to as the Secret Sidewalk.