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Surface geologist Dr. John C. Dohrenwend, left, and Colorado Riverkeeper John Weisheit tread across an eroding sediment bed in the Colorado River's channel through Cataract Canyon in southern Utah. Dried silt slumps toward the river, developing cracks up to five feet deep as layers of the sediment are washed out by the river below. The canyon, just north of the Lake Powell reservoir created by Glen Canyon Dam, has filled with silt and sediments when the waters of the reservoir rise in the canyon. Now with low water the river is eroding those lake sediments and washing them into Lake Powell, Dohrenwend asserts. He is studying the creation of the Colorado River's delta at Lake Powell and the erosion and motion of sediments into the lake. Dohrenwend, a retired U.S. Geological Survey geologist, fears the sediment flow may fill the reservoir more quickly than the builders of the Glen Canyon Dam thought. This would reduce the storage capacity of the reservoir and possibly compromise the dam itself. (Kevin Moloney for the New York Times)
Surface geologist Dr. John C. Dohrenwend, left, and Colorado Riverkeeper John Weisheit tread across an eroding sediment bed in the Colorado River's channel through Cataract Canyon in southern Utah. Dried silt slumps toward the river, developing cracks up to five feet deep as layers of the sediment are washed out by the river below. The canyon, just north of the Lake Powell reservoir created by Glen Canyon Dam, has filled with silt and sediments when the waters of the reservoir rise in the...
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