Big Tujunga Dam

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Big Tujunga Dam
FEMA - 45015 - The Big Tujunga Dam in California.jpg
The dam undergoing repairs in August 2010
Country United States
Location Angeles National Forest, Los Angeles County, California
Coordinates 34°17′36″N 118°11′18″W / 34.29333°N 118.18833°W / 34.29333; -118.18833Coordinates: 34°17′36″N 118°11′18″W / 34.29333°N 118.18833°W / 34.29333; -118.18833[1]
Opening date 1931
Owner(s) Los Angeles Department of Water and Power
Dam and spillways
Type of dam Concrete arch
Impounds Big Tujunga Creek
Height 208 ft (63 m)
Height (foundation) 244 ft (74 m)
Length 505 ft (154 m)
Width (crest) 8 ft (2.4 m)
Width (base) 73 ft (22 m)
Spillway type Concrete-lined overflow
Spillway capacity 90,000 cu ft/s (2,500 m3/s)
Reservoir
Creates Big Tujunga Reservoir
Total capacity 5,960 acre·ft (7,350,000 m3)
Active capacity 5,715 acre·ft (7,049,000 m3)
Catchment area 82 sq mi (210 km2)

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.[2]

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 project[edit]

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.[3] 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).[2] The seismic retrofit project was completed in July 2011 at a cost of $100 million.[4]

See also[edit]

References[edit]

  1. ^ "Big Tujunga Dam". Geographic Names Information System, U.S. Geological Survey. 1981-01-19. Retrieved 2011-10-16. 
  2. ^ a b "The Sustainability of Experience — Investing in the Human Factor". 28th Annual USSD Conference. United States Society on Dams. 2008. p. 59. Retrieved 2011-10-16. 
  3. ^ "Big Tujunga Dam Seismic Upgrade". Los Angeles Department of Public Works. 2006-01-05. Retrieved 2011-10-16. 
  4. ^ "Big Tujunga Dam Seismic Retrofit Project completed". Daily News. 2011-07-21. Retrieved 2011-10-16. 

External links[edit]

Media related to Big Tujunga Dam at Wikimedia Commons