Building a permanent dam
On August 19, 1969, researchers began studying the deposition of talus at the base of the falls. By drilling holes deep into the rocks, they hoped to learn more about how they were formed. However, it soon became apparent that the operation would not be as simple as the specialists had hoped.
In fact, engineers studying the American Falls concluded that the talus played a critical role in supporting the rock wall behind it. The many challenges the removal posed eventually led to an alternative plan thought up by the authorities. By building a permanent dam, they reasoned, they could raise the water level in the basin and submerge the powerful rocks.