Today, pavement and buildings cover some 60 percent of the watershed. The rainfall, unable to seep into the ground, flows into 400 miles of tributary drains, all of which dump into the LA River. These tributary drains, once historic creeks like Santa Susana, Browns, Dayton, Chatsworth, Limekiln, Wilbur, Aliso, Woodley, Pacoima, Bell Creek, Calabasas Creek and Burbank, have now mostly been lined with concrete.

The Convergence of Bell Creek with Calabasas Creek, next to the Canoga Park High School football field,marks the official start of the Los Angeles River.  From there, the river flows southeast to the Sepulveda Basin.

Normally dry, the 2.25-square mile reservoir above the Sepulveda Dam, known as the Sepulveda Basin, is used for winter flood control and ground water replenishment. Much of the Basin is a park, filled with soccer and baseball fields, children’s playgrounds and is the site of Lake Balboa. The river is a prominent part of the landscape.

With more than three miles of soft-bottom channel, a real river has sprung up, with willows, reeds and sagebrush. It’s picturesque and almost natural. This is, at this writing, perhaps the most delightful section of the River, a quiet place to study birds and plants, and a great place to share with friends and  family.  Bull, Hayvenhurst, and Haskell creeks, all tributaries, join the main river channel in the Basin.

The area adjoins the 225-acre Wildlife Reserve, where visitors are welcome, and which offers protected habitat for hundreds of species.

From the Sepulveda Basin, the river, once again a concrete channel, flows east. It passes beneath the 405 Freeway and moves through the cities of Van Nuys, Sherman Oaks and Studio City.

The Big Tujunga Wash, which drains the northwestern San Gabriel Mountains, joins the Pacoima Wash and meets the main river at the CBS studios in Studio City.

The Verdugo Wash, which drains the mountains above Glendale, La Cañada Flintridge, and Burbank, joins the LA River where the 5 and the 134 Freeways intersect.

The Glendale Narrows and the Elysian Valley areasare among of the most popular sections of the L.A. River. Located between Los Feliz and the river’s confluence with the Verdugo Wash, it’s the spot where the water table from the aquifers of the Valley pushes up at the edge of

Griffith Park. The concrete floor gives way to sand and gravel, and a diverse population of birds, fish, trees and reeds thrives here. Along the south bank runs one of the river’s nicest bike paths.

In Frogtown, the 5 Freeway again crosses the river and again, the bottom becomes concrete. The area gets its distinctive name from the many frogs (Western toads, actually) who once lived there. The inhospitable concrete, along with predators like herons, dramatically reduced the toads’ numbers. This area borders a large railyard known as Taylor Yard, a stone’s throw from the new Rio de Los Angeles State Park.

The Arroyo Seco Convergence is the section of the river where the native Gabrielino tribal village of Yangna, and the first pueblo of Los Angeles that followed it, were once located. The Arroyo Seco drains a watershed that covers the southwestern section of the San Gabriel Mountains above Pasadena. Many of the upper sections of the Arroyo Seco, already in a more natural state, are further being restored through the replanting of native trees, shrubs and grasses.  More restoration is being planned, along with hiking and equestrian trails, bike paths, and additional natural plantings in the section south of the Colorado Street Bridge. Where the Arroyo Seco flows alongside the Pasadena Freeway, it has been contained in a trapezoidal channel. A bike path runs along part of the bank, which heads toward the intersection of 5 and the 110 Freeways, and where it meets the LA River.

Downtown Los Angeles, perched on the western bank of the L.A. River, grew in a southerly direction. The sole surviving historic buildings from the early pueblo days are preserved next to Olvera Street.  The river channel then heads south, flows past the Arts District and through industrial neighborhoods, and is crossed by a series of historic bridges, designed by Merrill Butler and built in the late 1920s and 30s.  As it leaves downtown L.A., the river flows south-southwest, and soon runs parallel to the Long Beach (710) Freeway through the cities of Maywood, Bell, Cudahy and Commerce.

At the Rio Hondo Convergence, waters from the Rio Hondo (“Deep River”, seen on the right) join the main channel of the river (seen on the left). The Rio Hondo flows from the northeast, from the Whittier Narrows Reservoir in South El Monte.

Flood risks increase south of the convergence, which led the Army Corps of Engineers to propose increasing the height of the channel by 32 inches. FoLAR has proposed an alternative plan, which it claims can safeguard property owners and recharge groundwater at lower cost and with less disruption.

As The Lower Section of the river runs through the industrial landscape, it picks up more urban runoff. Here, it meets Compton Creek, the final tributary, which comes from the west. The final stretch of the Los Angeles River is in Long Beach, where an abundance of seabirds can be seen as the channel passes the various parks on its eastern banks.

During the severe flood of 1938, the river split around Long Beach. It cut off the city from the mainland and turned, briefly, into an island. It was floods like these, as well as those in the San Fernando Valley, that hastened the Army Corps’ work to contain the main channel in concrete. A reminder of these floods is in the name, Rattlesnake Island, now part of Terminal Island. During the annual floods, snakes washed downstream into the harbor and onto the island. Even now, after the big winter storms, snakes occasionally wash ashore along the Santa Monica Bay.

The river channel finally comes to an end as it mixes with sea water and flows into the Pacific at the Port of Los Angeles.