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
Course of the Colorado River is removed for irrigation here. The Gila Gravity Main Canal provides water for the Gila Valley in Arizona. The All-American Canal, which runs west to the Imperial Valley of California, is the largest irrigation canal in the world, capable of carrying – the entire natural flow of the Colorado prior to damming. The canal supplies more than half a million acres (2000 km) which due to its mild climate grows most of the winter produce in the United States. Below Imperial Dam the remnants of the Colorado river lessen in gradient and in its lower course flows through the Colorado