Lucky Peak Dam

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.[2] 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).[5]

Lucky Peak Dam
Aerial view from the west in June 1997
Location in the United States Show map of the United States Location in Idaho Show map of Idaho
Country	United States
Location	Ada County, Idaho
Coordinates	43°31′42″N 116°3′11″W[1]
Purpose	Flood control, irrigation
Construction began	1949 (1949)
Opening date	1955 (1955) [2]
Construction cost	$19 million (1955)
Owner(s)	U.S. Army Corps of Engineers[2]
Dam and spillways
Type of dam	Embankment dam
Impounds	Boise River
Height	340 ft (104 m) [2]
Length	2,340 ft (713 m) [2]
Reservoir
Creates	Lucky Peak Reservoir
Total capacity	307,000 acre-feet (379,000,000 m3) [2]
Catchment area	2,680 square miles (6,940 km2) [2]
Surface area	2,820 acres (11.4 km2) [2]
Normal elevation	3,050 ft (930 m)
Power Station
Commission date	1988 (1988)
Turbines	2 x 45 MW, 1 x 11 MW Kaplan-type[3][4]
Installed capacity	101 MW
Annual generation	321,790,000 KWh
Columbia River Basin

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.[6]

The dam was named after a nearby mountain in the Boise Range, about four miles (6 km) north of the dam (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).[7]

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.[8]