The flood in southeastern Idaho from the Teton Dam failure of June 5, 1976
The failure of the Teton Dam near Newdale, Idaho, June 5, 1976, caused a flood of unprecedented magnitude on the Teton River, lower Henrys Fork, and Snake River upstream from American Falls Reservoir. Eleven lives were lost. More than 180 square miles were inundated and damages reportedly were about $400 million. At the time of failure, the Teton Reservoir contained 251,700 acre ft of water. Approximately 173,000 acre-ft drained through the breached dam within 143 minutes, resulting in a peak discharge of 2.3 million ft 3 /s. A total of about 240,000 acre-ft drained from the reservoir within an 8-hour period. Between Teton Dam and American Falls Reservoir on Snake River, about 100 miles, the peak discharge and flood volume attenuated to 53,500 ft 3 /s is and 160,000 acre-ft, respectively. American Falls Reservoir stored the entire floodflow. The report presents peak discharges, flood volumes, profiles of the water surface, time-of-travel data, and geometric properties of 25 transverse cross sections. Hydrographs of groundwater levels at 50 sites adjacent to the flood area are presented. Analyses of surface water and ground water samples show the effect of the flood flow on quality of water within the flooded area.