The Rio Hondo (Spanish translation: "Deep River") is a tributary of the Los Angeles River in Los Angeles County, California, approximately long. As a named river, it begins in Irwindale and flows southwest to its confluence in South Gate, passing through several cities (though not the city of Los Angeles). Above Irwindale its main stem is known as Santa Anita Creek, which extends another northwards into the San Gabriel Mountains where the source, or headwaters, of the river are found.