Marble Canyon Dam States Geological Survey, which designated sites for "an unbroken string of [hydroelectric] dams from the mountains of Colorado and Wyoming to the last canyons of the Colorado River along the California/Arizona border". Although the Bureau of Reclamation expressed interest at this time in developing hydroelectric generation at the Marble site, these plans were postponed in favor of building the Hoover Dam, which would provide a much greater storage capacity for irrigation and flood control. However, once Hoover was completed the Bureau once again set its sights on the Grand Canyon, which has the greatest hydroelectric potential of any canyon in
Course of the Colorado River Colorado. Although the dams have mostly been erased by erosion, a small portion remains as Lava Falls, generally considered the most difficult and dangerous rapids for boaters on the Colorado River. The Colorado then swings sharply south and turns northwest north of Peach Springs, emerging from the Grand Canyon at the Grand Wash Cliffs, where it widens into the upper reaches of Lake Mead. The area also marks the general boundary between the Colorado Plateau and the Mojave Desert. Shortly west of that point it begins to form the border of Nevada to the north/west and Arizona to the south/east.