Taum Sauk is (was?) a reservoir in theSt. Francois mountain region in southern Missouri Ozarks. On December 14, 2005, the wall of the reservoir failed and released one billion gallons of water in 12 minutes. The resulting surge of water tore a path through the mountain leaving it bare down to the bedrock making geologists everywhere very very happy.
You can find it yourself on Google Earth using these coords: 37°32'07.79"N 90°49'06.80"W