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
Cottonwood Valley (Arizona and Nevada) Cottonwood Valley (Arizona and Nevada) Cottonwood Valley is a wide valley, on the Colorado River on the border between Mohave County, Arizona and Clark County, Nevada. It extends east and west from the river into both states and is the first wide valley south of the Black Canyon of the Colorado, the last in a series of great canyons the Colorado River passes through after leaving the Rocky Mountains on its way west and where it makes its turn to the south toward the Gulf of California. All of the Colorado River in Cottonwood Valley and the lower reach of