The concept of building a dam, evolved and grew until in 1919, a dam was proposed that would impound two to three million acre-feet of water. The American Falls project was formally authorized by the Secretary of Interior on September 18,1920.
The Falls were already being used by a small hydroelectric facility owned by Idaho Power, which had the priority water rights. When filled, the reservoir would cover important agricultural lands and would extend twenty-five miles upstream, covering 30,000 acres of Fort Hall Indian Reservation.
The Oregon Short Line Railroad ran its main line across a bridge at American Falls and miles of track would be flooded and the bridge raised 22 feet higher.
The dam was completed sixty days ahead of schedule on April 21, 1926. The dam’s gates were shut and water from the spring run-off began to collect in the reservoir. The giant grain elevators were not moved until late May 1926. On July 29, 1926, the “moving road” across the Dam construction site was officially closed, ending the relocation of American Falls.
Click images to enlarge.
