The Los Angeles River is an intermittent river flowing through Los Angeles County, California, from Canoga Park in the west end of the San Fernando Valley, 51 miles (82 km) southeast to its mouth in Long Beach. For most of its length, the river flows through a narrow concrete channel. Today, some environmental groups advocate the removal of concrete and the restoration of natural vegetation and wildlife.

Before the opening of the Los Angeles Aqueduct, the river was the primary source of fresh water for the city. Although the Los Angeles region still gets some of its water from the river and other local sources, most comes from several aqueducts serving the area. The river suffers severe pollution from garbage, urban runoff and treated sewage.