Walnut Creek is an urban stream in the San Gabriel Valley of Southern California, and is a tributary of the San Gabriel River. The creek begins at the Puddingstone Dam of Puddingstone Reservoir in Frank G. Bonelli Regional Park and flows westward for about 13 miles (21 km), through San Dimas, Covina, West Covina and Baldwin Park, to join the San Gabriel River in El Monte. Raging Waters Los Angeles is located adjacent to Walnut Creek just below Puddingstone Dam.