Hoover Dam with the Mike O'Callaghan – Pat Tillman Memorial Bridge

Spanning the Colorado River in Black Canyon between Arizona and Nevada 30 miles southeast of Las Vegas, the Hoover Dam was constructed in the 1930s. Originally known as Boulder Dam, the dam was renamed in 1947 for Herbert Hoover, who proved instrumental in getting the dam built as U.S. Secretary of Commerce and the 31st U.S. President. The concrete arch-gravity structure was intended to prevent flooding and provide much needed irrigation and hydroelectric power to arid regions of California and Arizona. At 726 feet high and 1,244 feet long, Hoover Dam was one of the largest manmade structures in the world at its construction and one of the world’s largest producers of hydroelectric power. At the generator room, visitors learn how water enters the intake towers next to the dam wall then is carried by penstock pipes to turbines, which spin the generators. The dam features nine generators on the Arizona side, eight on the Nevada side and two small ones for the internal power for the plant and dam workings. MIKE O’CALLAGHAN – PAT TILLMAN MEMORIAL BRIDGE The central portion of the Hoover Dam Bypass Project is called the Mike O’Callaghan–Pat Tillman Memorial Bridge (or Colorado River Bridge). Begun in January 2005, the 2,000-foot-long bridge features a 1,060-foot twin-rib concrete arch and spans the Black Canyon about 1,500 feet south of the Hoover Dam. Open to traffic in October 2010, the signature bridge conveniently connects the Arizona and Nevada Approach highways nearly 900-feet above the Colorado River. LAKE MEAD Named for Dr. Elwood Mead, U.S. Reclamation Commissioner between 1924 and 1936, Lake Mead is the largest manmade reservoir in the United States. The lake and its surroundings were established in 1964 as the Lake Mead National Recreation Area, the waters of which back up 110 miles behind Hoover Dam, which created it after its completion in 1935. Lake Mead can store nearly two years of average Colorado River flow, about 28.5 million acre feet of water. (An acre foot of water is 325,851 gallons, or enough to cover an acre to a depth of one foot.) This water is released in a regulated, year-round flow as needed.

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