It’s been two years now since I visited United States and stayed most of the time in Las Vegas, Nevada. I also had the chance to visit Hoover Dam or Boulder Dam as it is called by others. Here are some images and information I took from this amazing architecture during our visit last June 2008.
Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the U.S. states of Arizona and Nevada. When completed in 1936, it was both the world’s largest hydroelectric power generating station and the world’s largest concrete structure. It was surpassed in both these respects by the Grand Coulee Dam in 1945. It is currently the world’s 38th-largest hydroelectric generating station.
This dam, located 30 mi (48 km) southeast of Las Vegas, Nevada, is named after Herbert Hoover, who played an instrumental role in its construction, first as the Secretary of Commerce, and then later, as the President of the United States. Construction began in 1931 and the dam was dedicated by President Franklin D. Roosevelt on September 30, 1935 but it was not fully completed until 1936, which was still more than two years ahead of schedule. The dam and the power plant are operated by the Bureau of Reclamation of the U.S. Department of the Interior. Listed on the National Register of Historic Places in 1981, Hoover Dam was designated a National Historic Landmark in 1985.
Hoover Dam and its associated changes in water use had devastating impact on the Colorado River Delta at the mouth of the Colorado River. The construction of the dam has been credited as causing the decline of this estuarine ecosystem. For six years in the late 1930s, after the construction of the dam and while Lake Mead filled, virtually no flow of water reached the mouth of the river. The delta’s estuary, which once had a freshwater-saltwater mixing zone stretching 65 kilometres (40 mi) south of the river’s mouth, was turned into an inverse estuary where the level of salinity was actually higher closer to the river’s mouth.
The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, which imperiled many species adapted to the flooding, including both plants and animals.
The construction of the dam decimated the populations of native fish in the river downstream from the dam. Four species of fish native to the Colorado River, the Bonytail chub, Colorado pikeminnow, Humpback chub, and Razorback sucker, are currently listed as endangered by the U.S. federal government.
more infos here