Folsom Dam

Folsom Dam
Folsom Dam release
Location	Folsom, California
Coordinates	38°42′28″N 121°09′23″W / 38.7077°N 121.1565°W / 38.7077; -121.1565
Construction began	1951; 73 years ago (1951)[1]
Opening date	1956; 68 years ago (1956)[1]
Construction cost	US$81.5 million
Operator(s)	U.S. Bureau of Reclamation
Dam and spillways
Impounds	American River
Height	340 ft (100 m)[2]
Length	1,400 ft (430 m)[2]
Reservoir
Creates	Folsom Lake
Total capacity	977,000 acre⋅ft (1.205 km3)[3]
Inactive capacity	83,000 acre⋅ft (0.102 km3)[4]
Catchment area	1,875 sq mi (4,860 km2)[5]
Surface area	11,930 acres (4,830 ha)[3]
Power Station
Commission date	1955[6]
Hydraulic head	300 ft (91 m) (rated)[6]
Turbines	3x Francis
Installed capacity	198.7 MW[6]
Annual generation	528,427,000 KWh (2001–2012)[7]

Folsom Dam is a concrete gravity dam on the American River of Northern California in the United States, about 25 mi (40 km) northeast of Sacramento. The dam is 340 ft (100 m) high and 1,400 ft (430 m) long, flanked by earthen wing dams. It was completed in 1955, and officially opened the following year.

Located at the junction of the north and south forks of the American River, the dam was built by the United States Army Corps of Engineers, and was transferred to the United States Bureau of Reclamation upon its completion. The dam and its reservoir, Folsom Lake, are part of the Central Valley Project, a multipurpose project that provides flood control, hydroelectricity, irrigation, and municipal water supply. To increase Sacramento's flood protection to 200-year flood protection (meaning that the area is protected from a flood that has a 0.5% chance of occurring in any given year), the Corps of Engineers recently constructed an auxiliary spillway,^[8] which was completed in October 2017; it enables Folsom Dam operators to increase outflows to prevent the lake level from reaching or exceeding the height of the main dam gates.^[9]

Another Central Valley Project dam, Nimbus Dam, is located further down river.