June 5, 1976: The Teton Dam Collapse

The 305 foot tall Teton Dam designed to provide tremendous benefit to the farmers and residents of the Snake River area of Idaho. Built by the U.S. Bureau of Reclamation, it was supposed to eliminate the threat of spring floaods and provide year-round water for irrigation.

The earthen dam had just been completed in June of 1976, and men and equipment were still on-site. But the dam was defective.

Runoff from heavy snows during the winter had filled the reservoir behind the dam to capacity. Water began leaking from the dam on June 3rd, but there seemed to be no cause for alarm.

By 9:30 a.m. on Saturday morning June 5th, new leaks were spotted and bulldozers were used to try and shore up the dam. By 10:30 a.m., warnings were frantic as officials warned residents below the dam that it was about to break. Around 11 a.m., a whirlpool appeared as water was pouring through the earthen dam. The hole in the dam enlarged to 25 feet in diameter, nearly swallowing a bulldozer working to plug the hole. Shortly after that, the western side of the dam seemed to crumble.

Over 180 billion gallons of water were soon pouring down the Teton River Canyon. The towns of Wilford, Sugar City and Rexburg were inundated. Damages totaled $400 million. Eleven people lost their lives along with 13,000 head of cattle.

Had the disaster occurred during the nighttime hours, the death toll would likely have been in the thousands as sleeping residents would not have had time to hear the warnings to evacuate.

Category: Met 101/Weather History