Lucky Peak Dam is a rolled earth and gravel fill embankment dam in the United States, located on the Boise River in Ada County, Idaho. It is directly downstream of Arrowrock Dam, a concrete arch dam completed in 1915. This dam was designed by Mary Smith (a local architect). 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 3055ft above sea level, the empty reservoir's elevation (Boise River) is 2824ft.Construction began in November 1949 by the U.S. Army Corps of Engineers; the dam was operational in 1955 and its resulting reservoir is Lucky Peak Lake. 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.
