June 5, 2026 marked 50 years since the catastrophic failure of Teton Dam in southeastern Idaho. The 305-foot-high earthfill dam failed during its first filling in 1976, releasing an estimated 80 billion gallons of water. Eleven people were killed, communities downstream were devastated, and thousands of homes and businesses were damaged or destroyed.
The failure developed by internal erosion, or piping, involving the dam’s erodible core and highly fractured rock in the abutments. The independent review panel ultimately concluded that geological factors and design decisions combined to allow the failure to develop. For geotechnical engineers and engineering geologists, it remains one of the most important case histories involving dam siting, foundation treatment, filters, seepage, and the consequences of uncertainty in the subsurface.
The Bureau of Reclamation held a commemoration at the former dam site on the anniversary, with an emphasis on both the lives affected and the changes made to the agency’s Dam Safety Program afterward. Idaho Public Television also produced a new documentary, The Teton Dam Disaster, combining archival material and firsthand accounts from survivors.
This anniversary slipped past me in June, but it is too important a geotechnical case history not to recognize. The Bureau of Reclamation recap and the new documentary are good places to revisit what happened and why it still matters.
Read the Bureau of Reclamation’s 50th anniversary recap (was broken earlier…)
Or read about the Teton Dam on the USBR website as well.
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