17. Teton Dam
Year of Fail: 1976
Upon filling for the first time in 1976, the Teton Dam broke, sending water moving at 2,000,000 cubic feet per second into the Teton River canyon, flooding farmland and towns located downstream. Causing $1-2 billion in damages, 11 people and 13,000 head of cattle were killed. It was found that the permeable loess soil used in core construction and to patch foundation fissures allowed water to seep into the dam, causing internal erosion and ultimate collapse.