Humans Killed Cataract Canyon. It Brought Itself Back to Life

Sixty years ago, this stretch of river was considered as ferocious — and nearly as beautiful — as the Grand Canyon. Then, in 1963, the Glen Canyon Dam was built to store water for human use, which backed up the Colorado River behind it to create Lake Powell. The rising waters snaked upstream, inundating the main river and dozens of its side canyons. Here, at its farthest reaches in Cataract Canyon, the reservoir flooded rapids and then buried the riverbed, including the boulders that made up those rapids, in thick layers of sediment — a mud plug that built up to be so enormous that it flattened out the steep gradient of the riverbed that had made those rapids so fierce.