American Falls dam rehabilitation to begin next year

The U.S. Bureau of Reclamation plans a maintenance and rehabilitation project at the 94-foot-high American Falls Dam in 2020 and 2021.

The composite concrete and earth gravity-type dam was built on the Snake River near American Falls in 1928 and was reconstructed and replaced by the Bureau’s Safety of Dams Act in 1978.

The planned construction activities will address the need for replacement and repair of deteriorating concrete on the spillway, spillway gate operator decks, downstream dam face, adits, and stilling basin structures. All have experienced degradation after 40 years of service.

The work will consist of hydro demolition, cutting, removal and replacement of existing damaged concrete and reinforcing those components. The work will include replacement or modification of an existing drain grate in the stilling basin.

The construction will take place from June to November 2020 and mid-July to November 2021.

American Falls has a storage capacity of 1,700,000 acre-feet and is the largest reservoir in the Minidoka Project. About 889,282 acres of downstream land are irrigated annually with water stored there.