Marble Canyon Dam States Geological Survey, which designated sites for "an unbroken string of [hydroelectric] dams from the mountains of Colorado and Wyoming to the last canyons of the Colorado River along the California/Arizona border". Although the Bureau of Reclamation expressed interest at this time in developing hydroelectric generation at the Marble site, these plans were postponed in favor of building the Hoover Dam, which would provide a much greater storage capacity for irrigation and flood control. However, once Hoover was completed the Bureau once again set its sights on the Grand Canyon, which has the greatest hydroelectric potential of any canyon in
Risks to the Glen Canyon Dam annually at Glen Canyon, and as Lake Powell is the farthest large reservoir upstream on the Colorado River mainstem, the sediment load is completely trapped in the reservoir as the Colorado discharges into it. This sediment is creating a steadily advancing "toe" of sediment, i.e. an underwater alluvial fan, that is advancing towards the dam. It is estimated that the sediment will reach the dam base in a minimum as low as eighty to one hundred years or as far as 500 to 700 years, although it will take much more time for the sediment deposited there to reach higher