Hoover Dam the change, stating, "I didn't know Hoover was that small a man to take credit for something he had nothing to do with." Hoover Dam was recognized as a National Civil Engineering Landmark in 1984. It was listed on the National Register of Historic Places in 1981, and was designated a National Historic Landmark in 1985, cited for its engineering innovations. Other sources Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the
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