Located in Los Angeles, California, the Sepulveda Dam is a project of the U.S. Army Corps of Engineers, completed in 1941, at a cost of $6,650,561, to withhold winter flood waters along the Los Angeles River. It is located south of center in the San Fernando Valley, approximately eight miles east of the river's source in the western end of the Valley.
Sepulveda Dam, along with Hansen Dam located in the north San Fernando Valley, was constructed after the historic 1938 floods which killed 144 people. Sepulveda Dam was placed at what was at the time, the current edge of the city. East of the dam the river was crowded into a narrow bottom by the city's growth. One legacy of Sepulveda Dam is its flood control basin, a large and undeveloped area in the center of the Valley, used mostly for wildlife refuge and recreation. But another legacy of the 1938 Los Angeles River flood was the post-WWII channelization of all the Valley's dry washes, which along with the post-WWII rapid suburbanization left the Valley with hot, dry, concrete-lined river bottoms instead of greenbelts. Although now, in part, these are being devolved as interconnecting bike paths.
Behind the dam, the Sepulveda Basin is home to several large recreation areas including Woodley Park, a model aircraft field, The Japanese Garden, a wildlife refuge, a water reclamation plant, and an armory. The Basin is kept free of urban over-building so that water can build up there during a prospective hundred-year flood.