The Los Angeles River (, El Río de Nuestra Señora la Reina de los Ángeles de Porciúncula), historically known as by the Tongva and the by the Spanish, is a major river in Los Angeles County, California. Its headwaters are in the Simi Hills and Santa Susana Mountains, and it flows nearly from Canoga Park through the San Fernando Valley, downtown Los Angeles, and the Gateway Cities to its mouth in Long Beach, where it flows into San Pedro Bay. While the river was once free-flowing and frequently flooding, forming alluvial flood plains along its banks, it currently flows through a concrete channel on a fixed course, which was built after a series of devastating floods in the early 20th century.
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 receives some water from the river and other local sources, most of the water supply flows from several aqueducts serving the area. The Los Angeles River is heavily polluted from agricultural and urban runoff.
Fed primarily by rainwater and snowmelt (in winter and spring), the Donald C. Tillman Water Reclamation Plant in Van Nuys (in summer and fall), and urban discharge, it is one of the few low-elevation perennial rivers in Southern California. Some water usually reaches the ocean, even in the driest summers; although there are historical accounts of the river running dry, there has been constant flow of the river every month since recording of stream flow began in 1929. This is helped by the concrete channel, which limits absorption of water into the earth. Flow, while generally low in volume, can be extremely brisk even in summer.
Course
The Los Angeles River's official beginning is at the confluence of two channelized streams – Bell Creek and Arroyo Calabasas – in the Canoga Park section of the city of Los Angeles, just east of California State Route 27 (Topanga Canyon Boulevard), at (the east side of Canoga Park High School). Bell Creek flows east from the Simi Hills, and Arroyo Calabasas flows north from the Santa Monica Mountains. From there the river flows east through a concrete flood control channel and very soon receives Browns Canyon Wash, which flows south from the Santa Susana Mountains. The river then bends slightly south and receives Aliso Canyon Wash, whose watershed adjoins that of Browns Canyon. The river then flows through the district of Winnetka, then Reseda and enters the Sepulveda Basin, a flood-control reservoir formed by the Sepulveda Dam.
As the river proceeds into the usually-dry reservoir, it spills out into a channel that is similar to its historical, non-channeled form. It crosses under Balboa Boulevard and then receives Bull Creek. The river then passes through the outlet works of Sepulveda Dam, from the mouth. It flows again into a concrete channel and crosses under the San Diego (405) Freeway as it passes through Van Nuys, Sherman Oaks, and Studio City, still flowing east. Paralleling U.S. Highway 101 briefly, it then veers southeast, away from the highway, and receives from the left the Tujunga Wash, one of its largest tributaries, which flows southwest and south from the Angeles National Forest in the San Gabriel Mountains. The river then rounds a bend to the northeast, now in a concrete box culvert, and crosses under the Hollywood (170) Freeway and Highway 101, and receives Burbank Western Channel on the left bank, from the mouth.
The river then begins to parallel the Ventura (134) Freeway as it winds through North Hollywood and the city of Burbank. It then crosses under the Golden State (5) Freeway and makes a sharp bend to the south-southeast as it curves around Griffith Park. It receives from the left Verdugo Wash, which drains much of La Cañada Flintridge and Glendale as it flows from the San Gabriel Mountains south through a water gap in the Verdugo Mountains, and crosses under the Ventura Freeway. Here, the river begins to flow over a natural riverbed, but enters another concrete section soon after. Paralleling the Golden State Freeway for the next few miles, the river runs by the eastern side of Griffith Park and the Harding-Wilson Golf Course. It passes Silver Lake Reservoir, which is to the right, and crosses under the Glendale (2) Freeway, from the mouth.
Making two meanders as it flows in a southeasterly direction, the river parallels the interstate and Riverside Drive then crosses under the interstate and Arroyo Seco (110) Parkway as it flows east of Elysian Park. It then receives the Arroyo Seco, another major tributary, from the left. The river flows south past the Mission Junction, a large railroad yard on the left. It enters a wider concrete channel with sloped sides, and crosses under Cesar Chavez Avenue, the Hollywood (101) Freeway, and the San Bernardino (10) Freeway as it passes east of downtown Los Angeles, flowing past the East Los Angeles Interchange of the Santa Ana (101) Freeway, Pomona (60) Freeway, and Interstates 5 and 10 on the left. It then makes a gradual turn east and then turns southeast, flowing a few miles before it begins to parallel the Long Beach (710) Freeway near Maywood, Bell, Cudahy, and Commerce, from the mouth.
Paralleling the Long Beach Freeway south-southwest, the river then crosses under former California State Route 42 and the interstate as it receives the Rio Hondo from the left, from the mouth. The Rio Hondo ("deep river") now serves as a distributary for the San Gabriel River to the east via the Whittier Narrows Reservoir. The river then crosses under the Century (105) Freeway and shifts slightly southwest, then flows east of Compton and west of Bellflower. After crossing under the Artesia (91) Freeway, it receives Compton Creek from the right, from the mouth. After crossing under Interstate 405 for the second time, from the mouth, it draws close to the Dominguez Channel to the west and flows due south to its outlet in Long Beach, under Interstate 710, past the RMS Queen Mary, and into the Port of Long Beach.
History
Until the opening of the Los Angeles Aqueduct in 1913, the Los Angeles River was the main water source for the Los Angeles Basin. The river ran dry during the summers and flooded during winter months. Indigenous communities adapted to the climate surrounding the river, maximizing agricultural yields by rerouting the natural flow of the river and constructing water wheels along the river.
The river provided water and food to the Tongva people, hunters and gatherers who lived primarily off fish, small mammals, and the acorns from the abundant oak trees along the river's path. There were at least 45 Tongva villages near the Los Angeles River, concentrated in the San Fernando Valley and the Elysian Valley, in what is present-day Glendale. After the Spanish established Mission San Gabriel in 1771, they referred to the Tongva living in that mission's vicinity as Gabrieleño.
Alta California
In 1769, members of the Portolá expedition to explore Alta California were the first Europeans to see the river. On August 15, the party camped near the river, somewhere along the stretch just to the north of what is now the Interstate 10 crossing near downtown Los Angeles. Fray Juan Crespi, one of two Franciscan missionaries traveling with Portolá, named it el río de Nuestra Señora La Reina de Los Ángeles de Porciúncula. Crespi chose that name, because August 15 is the date of the yearly Catholic feast day in honor of the Virgin Mary's Assumption into Heaven and assuming the role as Queen of the Angels, to which the small Portiuncula chapel, where the Franciscan Order began in Assisi, Italy, is dedicated. The river was thereafter referred to as the "Porciuncula River". In later years, the "Los Angeles" part of Crespi's lengthy name won out.
Possession by the United States
Control of California, along with the rest of the northern part of the republic of Mexico, was wrested by the United States in the Mexican-American War (1846–1848). California became a state in 1850, and the Los Angeles area began to boom the following year. Generations of settlers and city managers drained, rerouted, polluted and overpopulated the river and its watershed.
The river was originally an alluvial river that ran freely across a flood plain that is now occupied by Los Angeles, Long Beach, and other townships in Southern California. Its path was unstable and unpredictable, and the mouth of the river moved frequently from one place to another between Long Beach and Ballona Creek. Floods damaged extensive amounts of farmland, destroying houses and killing people and livestock. Severe flooding encouraged those living near the river to adapt and construct further away from the river in order to prevent loss from flooding. In the early 19th century, the river turned southwest after leaving the Glendale Narrows, where it joined Ballona Creek and discharged into Santa Monica Bay in present Marina del Rey. However, this account is challenged by Col. J. J. Warner, in his Historical Sketch of Los Angeles County:"...until 1825 it was seldom, if in any year, that the river discharged even during the rainy season its waters into the sea. Instead of having a river way to the sea, the waters spread over the country, filling the depressions in the surface and forming lakes, ponds and marshes. The river water, if any, that reached the ocean drained off from the land at so many places, and in such small volumes, that no channel existed until the flood of 1825, which, by cutting a river way to tide water, drained the marsh land and caused the forests to disappear."The river was long joined by the San Gabriel River in present-day Long Beach, but in the Great Flood of 1862, the San Gabriel carved out a new course to the east, and has discharged into Alamitos Bay ever since. The arrival of the railroad accelerated the advancement in urbanization, as various government bodies subdued the river by reducing its flow. Until the 1900s the river was known to supply enough water to incorporate a system of wells to be built in order to supply freshwater to the city.
20th century
The Los Angeles Aqueduct was opened in 1913. The heavy flow of the Los Angeles River presented many issues, as it began to get exploited as a sewer system. Along with these uses, populations surrounding the river often tossed feces and waste into the river, along with dead dogs and horses (and the occasional dead human), in hopes that they would get washed down stream and released to the open ocean waters.
Water wars
In the early 1920s, the Los Angeles Department of Water and Power (led by the Los Angeles Board of Water and Power Commissioners) negotiated and gradually purchased almost all of Owens Valley farms and their corresponding water rights. The farmers with the most water banded together to form the Owens Valley Irrigation District in order to try to secure a better deal. When the Owens Valley Irrigation District did not succeed, they created three smaller groups in order to try to bargain. These groups were turbulent in their efforts; resorting to violence, trying to get the attention of state and national press, and calling for politician interference to support their demands for more compensation. This conflict was so highly disputed that the national press referred to it as "California's Little Civil War".
The St. Francis Dam was built starting in 1924 (and through 1926), leading to the creation of a large reservoir in San Francisquito Canyon, and provided water for Los Angeles. The dam collapsed in 1928.
The 1930s in particular saw rapid urban development in areas prone to river flooding. Despite smaller mitigation efforts than the St. Francis Dam, unpredictable and devastating floods continued to plague it well into the 1930s, including: