Channelization of the LA River

Los Angeles River Watershed is composed of the Los Angeles River and tributaries that include: Bell Creek, Browns Canyon Wash, Aliso Creek, Tujunga Wash, Verdugo Wash, Arroyo Seco, Rio Hondo, Arroyo Calabasas, and Compton Creek. It is located in Southern California between the San Gabriel River watershed and the Santa Monica Bay watershed. It covers an area of 831 square miles. Long before there was any permanent settlement in Los Angeles, the Los Angeles River would flow freely across the land. Naturally, the Los Angeles River does not have a constant water flow; it can be as little as a stream during dry seasons or become a full river on rainy seasons. Due to major flooding, the course of the river would constantly change; the river would occasionally empty out into Santa Monica, approximately 30 miles away from where it now resides in Long Beach. The first people to inhabit the area were the Tongva tribe. They understood the natural tendency of the river to flood and avoided permanent settlements near the river. The Spanish then moved into the area and began to establish permanent settlements. They, however, did not anticipate the destructive power of the floods. The Spanish were resilient, rebuilt and the city of Los Angeles continued to grow.
As the Los Angeles population continued to grow the floods did not cease to cause destruction. Major flooding events would cause damages ranging from $100 to $795 million. It was not until the concrete channel was constructed between the 1930’s to the 1960’s that the flooding was controlled. The concrete channel extends from the San Fernando Valley and empties out in Long Beach running a length of nearly 50 miles. The major flooding damages of the past have been avoided since then; the concrete channel has prevented $3.6 billion in flood damages. Although the damage costs have been greatly reduced, Los Angeles River and the Los Angeles Area have been affected by issues related to the concrete channel and its attempt to control flooding. Flood control was fueled by a philosophy (getting water off site as fast as possible) that has created multiple issues related to water. This philosophy has increased water runoff, diminished water quality and water supply, and created a negative condition for habitat to prosper in the Los Angeles River watershed.

The channelization of the Los Angeles River has caused major issues that need to be addressed.  Although the creation of this channel was deemed necessary at the time, its existence has forgone the positive effect of its initial flood control function and provided a list of significant issues. These issues include water runoff, water quality, water supply.  Change must be implemented in order to allow Los Angeles to move forward and continue to grow in a sustainable manner.


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