Country United States Type of dam Concrete arch Length 505 ft (154 m) Opened 1931 Impound Big Tujunga Creek | Opening date 1931 Impounds Big Tujunga Creek Height 63 m Catchment area 212.4 km² | |
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Location Angeles National Forest, Los Angeles County, California Owner Los Angeles Department of Water and Power Similar Big Tujunga Creek, Pacoima Dam, Tujunga Wash, Cogswell Dam, Santa Anita Dam | ||
Big Tujunga Dam is a concrete arch dam in Los Angeles County, California, spanning Big Tujunga Creek northeast of Sunland. Completed in 1931 by the Los Angeles Department of Water and Power, it serves mainly for flood control. The dam was originally planned as one of several similar flood-control dams inside Big Tujunga Canyon and was thus referred to as Big Tujunga Dam No. 1 until the large Hansen Dam was completed in 1940, eliminating the need for the other components of the original project.
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Map of Big Tujunga Dam, Tujunga, CA 91042, USA
Its reservoir is called Big Tujunga Reservoir, and has a capacity of 5,960 acre·ft (7,350,000 m3). Although it is located inside the Angeles National Forest, public access to the lake is forbidden. The water is kept at a low level except during the rainy season. Because of the small storage capacity of the reservoir, it has filled completely with sediment on several occasions, including 1969 and 2011; as a result frequent dredging is required to keep the dam operational.
Seismic retrofit projectEdit
In 1976, the dam was recognized as in danger of failure from earthquakes (the San Andreas Fault runs nearby) and the reservoir's level was temporarily restricted to about 25% of capacity. Approximately 75,000 cu yd (57,000 m3) of concrete was added to the dam, transforming it from a thin-arch to a thick-arch design. A new spillway was built and the original one was expanded, increasing the release capacity from 23,000 cu ft/s (650 m3/s) to more than 90,000 cu ft/s (2,500 m3/s). The seismic retrofit project was completed in July 2011 at a cost of $100 million.