Incompatible Uses: The Dichotomy between the Flood Control Use and Other Designated Beneficial Uses of Streams in the Los Angeles Basin

摘要

Historically, floods were a common natural phenomenon in the Los Angeles Basin due to the geographic and climatic conditions of the region. Intensive urbanization of the basin led to a drastic increase in the frequency, magnitude, and damages caused by floods, leading to the formation of the Los Angeles County Flood Control District in 1915 and the construction of networks of flood control infrastructures over several decades thereafter. Today, the Los Angeles County Flood Control System is one of the most complex systems of its kind in the world and consists of 19 major dams, 530 miles of open channels, 2,920 miles of underground storm drain conduits, and nearly 80,000 catch basins. Having core objectives of protecting life and property from floods, the system was designed to convey stormwater to the ocean as quickly as possible. As such, engineering measures have irreversibly transformed the basin's natural drainage system into an artificial network of channels and pipes. On the other hand, the enactment of the Clean Water Act in 1972 established a regulatory basis for the restoration and protection of the ecological integrity of the nation's waters. Accordingly, all waterbodies in the Los Angeles region, including most engineered flood control channels, were designated with beneficial uses such as in-stream recreation and aquatic habitat. Unfortunately, many of the beneficial use designations were ill-conceived and in conflict with the century-old flood control use. The notion of having the same level of protection and expectation for engineered channels and natural streams has created a tremendous challenge in reconciling the flood control use with other conflicting beneficial uses in urbanized environments such as the Los Angeles Basin. Reconciling the flood control and ecological health expectations in urban streams is critical if meaningful and attainable ecological restoration is desired in such environments.