WATER SECURITYReviving the Los Angeles River: Engineering Alongside Nature and Society
Reviving the LA River is a prime example of a large-scale infrastructure project that requires engineers to work alongside nature and society. A revived LA River can again serve as habitat for native vegetation and wildlife, improve water quality, aid water management, and contribute to cultural renewal.
Much of the Los Angeles River is currently a concrete channel. Angelenos often joke that it is hardly a river, given that it is frequently dry and perhaps better known as the location for motorcycle and car chases in Hollywood blockbusters. Yet, the concrete channel serves an important purpose. The channel and multiple dams were put in place as flood control measures by the U.S. Army Corps of Engineers after a series of devastating storms in the early 1900s (Gumprecht 2001). The concrete channel fixed in place a river that was previously a dynamic landscape that frequently flooded and changed course. The denuded and straightened channel also reduced flow resistance, easing the passage of high flows towards San Pedro Bay.
In many ways, this modern incarnation of the LA River is doing its job. Despite a barrage of record-breaking storms over the past two winters (DeFlorio et al. 2024), careful management has ensured that the river does not go over its banks and flood surrounding neighborhoods. But there is growing recognition that the river could be so much more.
Reviving the LA River is a prime example of a large-scale infrastructure project that requires engineers to work alongside nature and society. Historically, the LA River served as a vital source of food and water for the Tongva people. A revived LA River can again serve as habitat for native vegetation and wildlife, improve water quality, aid water management, and contribute to cultural renewal. Naturalizing sections of the river could help reduce the impact of urban heat islands and provide valuable open recreational space. Of course, all of this must happen without increasing flood risk in a changing climate.
Given the potential benefits, there is widespread support for a revival of the LA River. The U.S. Army Corps has conducted in-depth ecosystem restoration studies (USACE Los Angeles District 2015). The County of Los Angeles maintains a compelling LA River Master Plan (LA County Public Works 2022). The city and government agencies have purchased large sites adjacent to the river to enable restoration.[1] Despite these efforts, there is limited consensus among the project partners and the local community on how best to proceed.
