Eco In the Know reports that the force of water flowing from the U.S. Army Corps of Engineers-controlled Big Bend Dam, upstream of the inundated Fort Calhoun Nuclear Power Plant near Omaha on the historically flooded Missouri River, could put the dam at risk:
"Big Bend Dam, South Dakota. The Missouri is flowing through the emergency spillway at Big Bend Dam. The water shooting through the spillway gates is moving so fast and with such erosive power that it is back-cutting toward the earthen dam itself. Left unchecked, the water could threaten the structural integrity of the dam. Although at present, that scenario is highly unlikely. Nonetheless, the Army is concerned about the erosion. To address the issue, a dump truck hauled large blocks of quarried stone to the trouble spot. The Army plans on dropping the rock atop the eroded bank sections to halt the back-cutting. A civilian working for the Army acknowledged that the engineers did not expect to be in this predicament when they first opened the spillway gates to the Missouri’s floodwaters. The back-cutting caught the Army by surprise. But the military is on top of the problem, with tons of pink Sioux quartzite."
Arnie Gundersen at Fairewinds Associates has warned about the risk of an "inland tsunami" overwhelming Ft. Calhoun if an upstream dam fails.