Portions of Mills Park, Crestmoor, and Rollingwood are very hilly, featuring canyons and ravines. Creeks, many of them now in culverts, flow from springs in the hills toward San Francisco Bay. Just west of Skyline Boulevard and outside of city limits is San Andreas Lake, which got its name from the San Andreas Fault. The lake is one of several reservoirs used by the San Francisco Water Department, providing water to San Francisco and several communities in San Mateo County, including San Bruno west of I-280.