Hoover Dam Hoover Dam Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President Franklin D. Roosevelt. Its construction was the result of a massive effort involving thousands of workers, and cost over one hundred lives. Originally known as Boulder Dam from 1933, it was officially renamed Hoover Dam, for President Herbert Hoover, by a joint resolution of Congress in 1947. Since about 1900, the Black
Colorado River , poured into the sea. The United States Geological Survey (USGS) operates or has operated 46 stream gauges to measure the discharge of the Colorado River, ranging from the headwaters near Grand Lake to the Mexico–U.S. border. The tables at right list data associated with eight of these gauges. River flows as gauged at Lee's Ferry, Arizona, about halfway along the length of the Colorado and below Glen Canyon Dam, are used to determine water allocations in the Colorado River basin. The average discharge recorded there was approximately , per year, from 1921 to 2010. This figure has been heavily