Science and Technology
Teton Dam

The Teton Dam was located in Fremont County, Idaho, in the Teton River Canyon above Wilford. It was just completed in 1976. There were workmen and machinery still at the site. The reservoir was full from spring runoff with 260,000 acre feet of water.

On Saturday, June 5, 1976, around 11 a.m., a whirlpool was spotted in the water above the dam. Suddenly the western third of the dam disintegrated. An estimated 80 billion gallons of water was loose and headed for the Upper Snake River Valley.

By evening, the reservoir had drained completely. The water in the valley below was still moving. It tore through Wilford, Sugar City, and Rexburg. When it reached the south fork of the Snake River, the rush of water turned west and went around the Menan Buttes, rolling through Roberts before turning south again.

Idaho Falls had nearly two days to get ready for the water. The Snake River runs right through town. The main concerns were businesses along the river and the safety of older bridges. Trenches were dug around the end of the Broadway Bridge to divert pressure.

The American Falls Dam was old and already holding back a vast amount of water. It stood between the flood waters and the rest of the Snake River Plain. Officials were concerned about its ability to hold the sudden rush of water coming at it and had begun releasing water immediately. The American Falls Dam held, and the flood was over.

Cleaning up after the tragedy would require the remainder of the summer. Thousands of volunteers from the region, especially Utah, came in on buses to help. The collapse of the dam was blamed for the deaths of 11 persons.

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