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). The dam is also in close proximity to the .