The San Gabriel River-Coyote Creek Creek Watershed covers 85.49 square miles in the northwest corner of Orange County. This watershed includes the cities of Fullerton, Buena Park and parts of the cities of Anaheim, Brea, Cypress, Fullerton, La Habra, La Palma, Los Alamitos, Placentia and Seal Beach. Coyote Creek, its main tributary, flows from Riverside County and empties into the San Gabriel River.
In 2001, the U.S. Army Corps of Engineers initiated a comprehensive watershed study. A Reconnaissance Study was completed in June 2001. Although it is titled the "Westminster Watershed Reconnaissance Study", it covers three Orange County watersheds: Coyote Creek, Carbon Creek, and Westminster.