History of the Grand Canyon area stretched along a 278-mile (447 km) segment of the Colorado River from the southern border of Glen Canyon National Recreation Area to the eastern boundary of Lake Mead National Recreation Area. Grand Canyon National Park was designated a World Heritage Site on October 24, 1979. In 1935, Hoover Dam started to impound Lake Mead south of the canyon. Conservationists lost a battle to save upstream Glen Canyon from becoming a reservoir. The Glen Canyon Dam was completed in 1966 to control flooding and to provide water and hydroelectric power. Seasonal variations of high flow and flooding in the spring and
Risks to the Glen Canyon Dam Dam forming Lake Havasu, Palo Verde Dam, and other dams and reservoirs. Because Glen Canyon Dam is also the central element of the Colorado River Storage Project, a failure may, depending on the volumes of water released and the damage caused, limit or completely cut off water supply to residences or farmlands along the Colorado River, and even into southern California depending on damage to canal headworks. The failure of Glen Canyon Dam would also destroy up to 964 known archaeological sites, including 264 that it currently affects in the Grand Canyon. Risks to the Glen Canyon Dam Glen Canyon