Lucky Peak Dam

Lucky Peak Dam
Aerial view from the west in June 1997
Location in the United States
Location in Idaho
CountryUnited States
LocationAda County, Idaho
Coordinates43°31′42″N 116°3′11″W / 43.52833°N 116.05306°W / 43.52833; -116.05306
PurposeFlood control, irrigation
Construction began1949 (1949)
Opening date1955 (1955)
Construction cost$19 million (1955)
Owner(s)U.S. Army
Corps of Engineers
Dam and spillways
Type of damEmbankment dam
ImpoundsBoise River
Height340 ft (104 m)
Length2,340 ft (713 m)
Reservoir
CreatesLucky Peak Reservoir
Total capacity307,000 acre-feet (379,000,000 m3)
Catchment area2,680 square miles (6,940 km2)
Surface area2,820 acres (11.4 km2)
Normal elevation3,050 ft (930 m)
Power Station
Commission date1988 (1988)
Turbines2 x 45 MW,
1 x 11 MW
Kaplan-type
Installed capacity101 MW
Annual generation321,790,000 KWh

Lucky Peak Dam is a rolled earth and gravel fill embankment dam in the western United States, located on the Boise River in southwestern Idaho. In Ada County east of Boise, it is directly downstream of Arrowrock Dam, a concrete arch dam completed in 1915. At the time of its construction in the early 1950s, Lucky Peak's primary purpose was flood control, with a secondary purpose of irrigation. The normal operating elevation of the full reservoir is 3,055 feet (931 m) above sea level, the empty reservoir's elevation (Boise River) is 2,824 feet (861 m).

Construction began in November 1949 by the U.S. Army Corps of Engineers. Most of the federal dams in southern Idaho, including the others on the Boise River, were built by the Bureau of Reclamation, not the Corps of Engineers. The Idaho Power Company, a private utility, built multiple hydroelectric dams on the Snake River.

Located along State Highway 21, ten miles (16 km) upstream from the city of Boise, it was built without hydroelectric power generation. Construction of the powerhouse began in 1984 and it became operational in 1988, generating electricity primarily for Seattle City Light.

The dam was named after a nearby mountain in the Boise Range, about four miles (6 km) north of the dam (43°36′18″N 116°03′43″W / 43.605°N 116.062°W / 43.605; -116.062). The summit elevation of Lucky Peak mountain (a.k.a. Shaw Mountain) is 5,904 feet (1,800 m).

The dam forms Lucky Peak Lake and is surrounded by Lucky Peak State Park.

The dam is also in close proximity to the Lucky Peak Dam Zeolite Occurrence.