Teton Dam
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| Teton Dam | |
 The reservoir behind the Teton Dam was emptied within hours of the initial breach |
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| Official name | Teton Dam |
|---|---|
| Impounds | Teton River |
| Locale | Fremont / Madison counties, Idaho |
| Length | 3,100 feet (940 m) |
| Height | 305 feet (93 m) |
| Width (at base) | 1,700 feet (520 m) |
| Construction began | 1975 |
| Opening date | 1976 |
| Construction Cost | $48,825,000 |
| Reservoir information | |
| Creates | Teton Reservoir |
| Capacity | 234,259 acre feet (288,954,000 m3) |
| Maintained by | United States Bureau of Reclamation |
The Teton Dam was a federally built earthen dam on the Teton River in southeastern Idaho, set between Fremont and Madison Counties, USA which when filling for the first time suffered a catastrophic failure on June 5, 1976. The collapse of the dam resulted in the deaths of 11 people[1] and 13,000 head of cattle. The dam cost about USD $100 million to build, and the federal government paid over $300 million in claims related to the dam failure. Total damage estimates have ranged up to $2 billion.[2] The dam was never rebuilt.
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[edit] Geology
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, highly fissured and unstable. Test boreholes, drilled by Bureau engineers and geologists, showed that one side of the canyon was highly fissured, a condition unlikely to be remediated by the Bureau's favoured method of "grouting" (injecting concrete into the substrates under high pressure). No seepage was noted on the dam itself before the date of the collapse. However, on June 3, 1976 workers found two small springs had opened up downstream.
[edit] The collapse and flood
At the time of the collapse, spring runoff had almost filled the new reservoir to capacity, with a maximum depth of 240 feet (73 m). Water began seeping from the dam on the Thursday before the collapse, an event not unexpected for an earthen dam.
At 7:30 a.m. on Saturday, June 5, 1976, a muddy leak appeared, suggesting sediment was in the water, but engineers did not believe there was a problem. By 9:30 a.m. the downstream face of the dam had a wet spot on it and embankment material began to wash out. Crews with bulldozers were sent to plug the leak, but were unsuccessful. Local media appeared at the site, and at 11:15 officials told the county sheriff's office to evacuate 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 11:55 a.m. Mountain Daylight Time (UTC-6:00), the top of the dam collapsed; two minutes later the remainder disintegrated. By 8:00 p.m. that 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. To the southwest, communities 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 American Falls Dam downstream, engineers increased discharge by less than 5% before the flood arrived. [3] That dam held, and the flood was over, but tens of thousands of acres of land near the river were stripped of topsoil.[2] Cleaning up took the rest of the summer.
[edit] Rebuilding and claims
After the dam's collapse, cleanup and rebuilding of damaged property 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.[citation needed] The dam was never rebuilt.[1]
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 1980's. 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.
As of July 2009, there is speculation about rebuilding the Teton Dam. $400,000 of the $800,000 needed has already been set aside by the Bureau of Reclamation with the purpose of investigating the feasibility of rebuilding. A local Idaho news station, "Local News Channel 8" ran a two part special on the process and reactions by local residents.
[edit] Cause of the collapse
A wide-ranging controversy erupted from the dam's collapse. According to the Bureau of Reclamation,
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.[4]
A recent study[5] has blamed the collapse on fissured (cracked) Rhyolite in the foundations of the dam that allowed water to seep under the dam and on the permeable Loess (a type of soil) used in the core. The permeable Loess was cracked. It is argued that the combination of these materials allowed water to seep through the dam and led to the piping (erosion) that eventually caused the dam's collapse.
[edit] See also
[edit] Notes
- ^ a b Doug Cantor (27 July 2007). "5 of the largest, oddest and most useless state projects". CNN. http://www.cnn.com/2007/LIVING/wayoflife/07/26/mf.gov.projects/index.html. Retrieved on 2007-07-29.
- ^ a b Marc Reisner (1993). Cadillac Desert. pp. 407. ISBN 0-14-017824-4.
- ^ "Data From American Falls Dam". Zeb Palmer (data courtesy Bureau of Reclamation). http://www.zebpalmer.com/oldblogarchive/teton-dam-failure-actual-data-for-american-falls/. Retrieved on 2008-12-20.
- ^ "The Failiure of Teton Dam". Bureau of Reclamation. http://www.usbr.gov/pn/about/Teton.html. Retrieved on 2007-07-29.
- ^ http://www3.interscience.wiley.com/journal/119985647/abstract?CRETRY=1&SRETRY=0
[edit] External links
- The Teton Basin Project, Eric A. Stene, Bureau of Reclamation History Program, 1996
- US Bureau of Reclamation site with several photos
- "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 oral history interviews of those living in the area when the disaster occurred.
- Mrs. Olsons Slides showing progressive dam erosion damage
- Data from American Falls Dam (downstream) from the Teton Dam Failure
- bureau of reclamation
Coordinates: 43°54′38.32″N 111°32′27.63″W / 43.9106444°N 111.5410083°W
