Teton Dam

The reservoir behind the Teton Dam was emptied within hours of the initial breach.

The Teton Dam was a federally-built dam on the Teton River in southeastern Idaho in the United States which suffered a spectacular failure on June 5, 1976. The collapse of the dam resulted in the loss of 11 lives. The dam cost about USD $100 million to build, and the federal government paid over $300 million in claims related to the dam failure. The dam was never rebuilt.

Contents

1 Description and geology
2 The collapse and immediate aftermath
3 Rebuilding and claims
4 Cause of the collapse
5 See also
6 External links

Description and geology

The ruins of the Teton Dam.

The dam was located in the Teton Canyon approximately 44 miles (71 km) northeast of the city of Idaho Falls. It was a 305 foot (93 m) high earthfill dam intended for irrigation, electricity, flood prevention, and recreation. The dam was built by the United States Bureau of Reclamation, which later received most of the blame for the collapse. The site of the dam is accessible to the public.

The dam site is located in the eastern Snake River Plain, which is a broad tectonic depression on top of rhyolitic ash-flow tuff. The tuff, a late-Cenozoic volcanic rock dating to about 1.9 million years, sits on top of sedimentary rock. The area is very permeable, but no seepage was noted on the dam itself before the date of the collapse. Several springs had opened up downstream a few days before, however.

The collapse and immediate aftermath

At the time of the collapse, spring runoff had almost filled the new reservoir to capacity, with a maximum depth of 240 feet. Water began seeping from the dam on the Thursday before the collapse, an event not unexpected for an earthen dam.

On the morning of Saturday, June 5 a new leak appeared. Bulldozers and crews were sent to plug the leak, but were unsuccessful. Local media appeared at the site, and an alarm was raised to downstream residents. Work crews were forced to flee on foot as the widening gap swallowed their equipment. The operators of two bulldozers caught in the eroding embankment were pulled to safety with ropes. At around 11:57 a.m. Mountain Standard Time (UTC-7:00), the dam collapsed. By evening the reservoir had completely emptied.

The communities immediately downstream, Rexburg, Wilford, Sugar City, Salem and Hibbard, suffered horribly. Thousands of homes and businesses were destroyed. One estimate placed damage to Rexburg, population 10,000, at 80 percent of existing structures. The small community of Sugar City was literally wiped from the river bank. Communities to the southwest, such as Roberts on a lower section of the Snake River, received significant damage. The city of Idaho Falls, even further down on the flood plain, had time to prepare. At the old and unstable American Falls Dam downstream, engineers released water before the flood arrived. That dam held, and the flood was over. Cleaning up took the rest of the summer.

Rebuilding and claims

Rebuilding after the dam's collapse continued for several years. Within a week after the disaster, President Gerald Ford requested a $200 million appropriation for initial payments for damages, without assigning responsibility for Teton Dam’s failure.

The Bureau of Reclamation set up claims offices in Rexburg, Idaho Falls, and Blackfoot. Disaster victims filed over 4,800 claims by January 4, 1977, totalling $194 million. The Federal government paid 3,813 of those claims, $93.5 million, by that date.

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.

Cause of the collapse

A wide-ranging controversy erupted from the dam's collapse. According to the Bureau of Reclamation site (see references below), "Today, Bureau of Reclamation engineers assess all Reclamation dams under strict criteria established by the Safety of Dams program. Each structure is periodically reviewed for resistance to seismic stability, internal faults and physical deterioration."

External links

[The Teton Basin Project], Eric A. Stene, Bureau of Reclamation History Program, 1996
[US Bureau of Reclamation site with several photos]
[Informative geology site at the U of California, Santa Barbara]
[More geology, US Bureau of Reclamation]
[University of Utah site with many gripping photographs]
["The Bureau That Changed the West" One That Got Away: Teton Dam] (site critical of USBR)
[Teton Dam Flood Museum, Rexburg, Idaho]
[Teton Dam Collection - Oral History reports and newspaper articles], includes more than 50 PDF'd (i.e., now online) oral history interviews of those living in the area when the disaster occurred.
[Mrs. Olsons Slides showing progressive dam erosion damage]