The Los Angeles River is a short, largely seasonal river flowing through Los Angeles County, California. It is formed by the union of Bell Creek and the Arroyo Calabasas in the southwestern San Fernando Valley. Other major tributaries are the Tujunga Wash, the Western Burbank Channel, the Verdugo Wash, the Arroyo Seco, the Rio Hondo, and Compton Creek. It flows eastward through the San Fernando Valley until turning southeast near the Hollywood Hills, in the city of Burbank. Prior to 1825, it then turned southwest, joining Ballona Creek and discharging into Santa Monica Bay. However, during a catastrophic flash flood in that year, its course was converted to its present one, flowing due south just east of present-day downtown Los Angeles and discharging into San Pedro Bay. (Prior to another major flood in 1862, it was joined by the San Gabriel River in present-day Long Beach, but in that year the San Gabriel carved out a new course six miles to the east, and has discharged into Alamitos Bay ever since.) The river's main sources come from the Santa Monica and San Gabriel Mountains, although much of the water actually comes from urban runoff.

Until the opening of the Los Angeles Aqueduct, the Los Angeles River was the primary water source for the Los Angeles Basin, and much of its channel was dry except during the winter rains. Unpredictable and devastating floods continued to plague it well into the 1930s (most notably the catastrophic 1938 flood that precipitated the recall of corrupt Los Angeles mayor Frank L. Shaw), leading to calls for flood control measures. The Army Corps of Engineers duly began an ambitious project of completely encasing the river's bed and banks in concrete, with only a trickle of water usually flowing down its middle. Ever since, it has primarily served as a flood control channel, fed by storm drains. The only portions of the river in which it is not completely paved over are in the flood control basin behind the Sepulveda Dam near Van Nuys; a three mile stretch east of Griffith Park known as the Glendale Narrows; and along its last few miles in Long Beach.

Sepulveda Basin is a flood-control basin to control floodwater runoff. Except for infrequent but dramatic flood episodes, this otherwise dry-land flood control basin, most of which is leased from the Corps by the City of Los Angeles Department of Recreation and Parks, plays host to diverse uses today including athletic fields, agriculture, golf courses, a fishing lake, parklands, a sewage treatment facility, and a wildlife reserve.

The river's southern stretch forms the heart of an industrial corridor stretching nearly unbroken from Lincoln Heights to Long Beach. In

Los Angeles River, looking east (downstream) at the Glendale Narrows.

Communities along the banks of the Los Angeles River include: