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July 24, 2014
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The River Be Dammed?

Lower Teton claims a turblulent past, uncertain future

On the morning of June 5, 1976, part-time Teton Valley resident Harold K. Dunn, M.D., was departing Salt Lake City International Airport for Driggs when the air traffic controller announced that the Teton Dam had failed. Area pilots were asked to assist with radio relays, and Harold circled the flooded area in his Cessna Skymaster for two hours, until he ran low on fuel. He took these photos (pages 49 and 50) from his airplane.

On the morning of June 5, 1976, part-time Teton Valley resident Harold K. Dunn, M.D., was departing Salt Lake City International Airport for Driggs when the air traffic controller announced that the Teton Dam had failed. Area pilots were asked to assist with radio relays, and Harold circled the flooded area in his Cessna Skymaster for two hours, until he ran low on fuel. He took these photos (pages 49 and 50) from his airplane.

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North of Tetonia, just beyond the Highway 33 bridge, the Teton River transforms from a tranquil, meandering spring creek into a rollicking torrent that plunges through a steep-walled gorge of volcanic rock. With just a few access points, this canyon is known today only by a lucky few anglers as a treasure trove of native cutthroat trout. At the take-out for this remarkable stretch of wild river, however, stands an imposing pyramidal structure that serves as monument to the lower Teton’s tragic past. The earthen remains of the Teton Dam, flanked by a vestigial spillway, also serve as a reminder that the future of the canyon is marked by uncertainty.

A ‘Colossal and Dramatic Failure’

Authorized by Congress in 1964, the Teton Dam was designed to supply irrigation water, produce hydroelectric power, provide recreation on its reservoir, and control periodic floods in the Rexburg area. Controversy began long before construction, with a group of environmental organizations and individuals, headed by Trout Unlimited, filing an injunction alleging that the dam proposal violated numerous laws and posed potential public safety hazards. After a short trial and numerous appeals, the injunction was resoundingly denied.

Geology, weather, and labor unions provided more challenge to the dam’s progress than the courts did. Difficulty filling the highly fractured rock along the canyon’s north wall plagued the project from its inception. Embankment excavation was slowed by repeated rain and snow and the need to clear what Teton Valley resident Jay Calderwood, who worked as a heavy equipment operator for dam contractor Morrison-Knudsen, describes as “a good ten feet of mud and willows until we got down to the solid gravel down at the bottom.” And a labor strike in the summer of 1974 stopped all work on the dam during prime construction season.

In the early spring of 1976, just after the reservoir began to fill, Pacific storms deposited heavy mountain snows. Anticipating above-average runoff, the Bureau of Reclamation requested permission to double the standard rate of filling.

The request was merely a formality; the main outlet works, which would allow dam personnel to release water from the reservoir and slow the rate of filling, were not yet functional. The snowmelt-swollen torrent of the Teton River filled the reservoir at more than four times the expected rate, straining the new dam. Beginning in early June, a series of leaks was discovered.

Calderwood, who had been promoted to excavation foreman, clearly remembers the morning of June 5, 1976. “I was at home when I got the call—it was a Saturday morning,” he says. “They told me the dam was leaking, but I figured it wasn’t any big deal, probably just a little water coming around the spillway, and I remember telling my wife I’d be home soon. When I drove up to the dam and saw all that water gushing out the side, just gushing, I thought, ‘Oh, my word.’ It was awesome, just awesomely frightening.”...(continued)

 

 

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