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
Steamboats of the Colorado River Mexico Territory, and Nevada state. They remained the primary means of transportation of freight until the advent of the more economical railroads began cutting away at their business from 1878 when the first line entered Arizona Territory. Steamboats were tried on the upper Colorado River: in Glen Canyon; on the Green River in Utah and Wyoming; and on the Grand River, (renamed as the upper part of the Colorado River after 1921), above its confluence with the Green River in Utah and in Colorado. These attempts in the late 19th Century and early 20th Century met with little success. The