Risks to the Glen Canyon Dam that the resulting flood would scour the bottom few hundred feet of the Grand Canyon, overtop Hoover Dam, and cause severe damage all along the lower Colorado River. In the event of a complete dam failure with Lake Powell at high pool, about of water would surge out of Lake Powell at an initial depth of over . Downstream communities and perhaps every dam along the river, excluding possibly Hoover Dam, as well as riverside lowlands, would be inundated or severely damaged. Located downstream from Glen Canyon Dam are Hoover Dam forming Lake Mead, Davis Dam forming Lake Mohave, Parker
Risks to the Glen Canyon Dam mode for Glen Canyon dam will likely be an overtopping one spring caused by insufficient storage capacity (either a huge inflow, bigger than 1983, or insufficient storage capacity because the lake was too full of either water or sediment). An example of the fast deposition rate of Colorado River sediment is found in Lake Mead itself, where, before the completion of Glen Canyon Dam, ten percent of its storage was already compromised by sediment. When Lake Powell levels drop, sediments deposited in its upper reaches are carried into the receding water by the Colorado and its tributaries. One large flash