As long as the laws of physics hold, large reservoirs must fill with mud. After Lake Powell fills, the Colorado River will meander across a mud flat and plunge down the face of Glen Canyon Dam in a waterfall that will undercut and eventually collapse the dam. In time, the river will remove the dam debris and lake sediments as though they never existed. Dams imprison rivers, but eventually they annihilate their jailers and escape. Like the truth, a river will out.