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Dam You

The Teton River runs through eastern Idaho. There used to be a dam on the river called, oddly enough, Teton Dam.

After much legal rambling and appeals and other issues, like being built in a seismically active area, the dam was completed in November of 1975.

On June 3 and 4, 1976, three small springs were discovered downstream of the dam, although the water running through the leaks was clear and such leaks are not unexpected for an earthen dam. At the time, the reservoir was almost at capacity, with a maximum depth of 240 feet. The only structure that had been initially prepared for releasing water was the emergency outlet works, which could carry just 850 cubic feet per second. The main outlet works and spillway gates were not yet in service; the gates were cordoned off by steel walls while they were being painted.

At 730 am on June 5, a muddy leak appeared. The mud indicated sediment was inside. Engineers were not worried about it. Two hours later the downstream face of the dam had developed a wet spot, which began to discharge water at 20 to 30 cubic feet per second

The embankment began to wash out and bulldozers were sent in to try to fill up the leak. Media began to show up at 1115 am, and officials began announcing evacuation of everyone downstream.

Work crews had to get away on foot as the breach got bigger and bigger. Two bulldozer operators had to be rescued by rope.

Just before noon, the top of the dam collapsed into the reservoir. Then, only 2 minutes later the entire right 1/3 bank of the dam wall disintegrated.

Over 2 million cubic feet of water per second poured out of the break, which is many times more than the flow rate of Niagara Falls.

By 8:00 pm, the reservoir had completely emptied, although over two-thirds of the dam wall remained standing. The reservoir was 240 feet deep.

One estimate placed damage to Hibbard and Rexburg area, with a population of about 10,000, at 80% of existing structures.

The Bureau of Reclamation set up claims offices in Rexburg, Idaho Falls, and Blackfoot. By January 4, 1977, disaster victims filed over 4,800 claims totaling $194 million. By that date, the federal government paid 3,813 of those claims, $93.5 million. Originally scheduled to end in July 1978, the claims program continued into the 1980s. At the end of the claims program in January 1987, the federal government had paid 7,563 claims for a total amount of $322 million.

The collapse of Teton Dam resulted in eleven deaths, and killed 16,000 livestock. Total damage estimates have ranged up to $2 billion.

Well, there ya have it. Thanks for reading again everyone, hope you had a safe holiday last week, see ya next week!

Article published on June 5th, 2023 by Greg Dixon

HLEW Weather Rewind

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