After the completion of Hoover Dam in 1935, sediment began accumulating in the new reservoir as the flow of the Colorado River was captured by the rising waters of Lake Mead. Initial estimates were that the new reservoir would last a little over 200 years as it filled with fine silt and sand from the high sediment load carried by the Colorado River. However, revised estimates in 1948 based on new data increased the life expectancy of the reservoir to more than four centuries.
With the completion of Glen Canyon Dam in 1963 upstream of Hoover Dam, sediment volume entering Lake Mead from the Colorado River was reduced to only about a tenth of its previous volume. Much of the sediment is now trapped within Lake Powell behind Glen Canyon Dam. With the reduced sediment input into Lake Mead, the lifetime of the reservoir has been extended to potentially more than a thousand years.