American Falls Dam, Power County, Idaho
Nestled in Power County, Idaho, American Falls Dam stands as a significant structure on the Snake River. It serves multiple purposes including flood control, irrigation, and recreation. This concrete gravity-type dam, with its expansive reservoir, has played a crucial role in the region’s development since the early 20th century.
Construction and History
The original American Falls Dam was constructed in the 1920s by the United States Bureau of Reclamation. The construction necessitated the relocation of a significant portion of the town of American Falls, marking a monumental change for local residents. In 1978, a new dam was completed, and the original structure was demolished. This modern dam was an essential upgrade to meet the growing needs of the region.
Geology and Geography
The area where the dam stands has a rich geological history. Over one million years ago, during the late Pliocene, a lava dam created a shallow lake in the Raft River area. The basin was subsequently filled with sediments, known as the Raft Formation. The Snake River, over time, has been repeatedly dammed by basalt flows, creating reservoirs that deposited various sediments.
Today, the dam is situated at an elevation of 4,357 feet above sea level on the Snake River Plain. The reservoir extends into Bingham County and Bannock County, enhancing its significance across a broader region. The original American Falls were characterized by the river narrowing and cascading over basalt in a series of drops, a landscape that the dam has since altered.
Dam and Reservoir Specifications
American Falls Dam, with a height of 94 feet and a length of 5,277 feet, impounds the Snake River, creating the vast American Falls Reservoir. This reservoir has a total capacity of 1,671,300 acre-feet and plays a vital role in water management in the area. The normal elevation of the reservoir is 4,354 feet above mean sea level.
Power Generation
The reservoir not only serves irrigation and flood control purposes but also facilitates power generation. Operated by the Idaho Power Company, the dam’s power station houses three turbines with an installed capacity of 112 MW, contributing to the region’s energy needs.
Environmental and Recreational Impact
American Falls Dam and its reservoir have significantly influenced the local environment and recreational opportunities. The reservoir is a popular destination for various water-based activities, including fishing, boating, and swimming. The surrounding areas offer camping sites and hiking trails, making it a favorite spot for outdoor enthusiasts.