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
Glen Canyon Dam about 5 million people in Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming, and is sold to utilities in these states as 20-year contracts. Power sales have been managed by the Western Area Power Administration since 1977. Glen Canyon Dam generates enough power to offset 6.7 billion pounds (3 billion kg) of carbon dioxide emissions each year. However, drought conditions in the 21st century have reduced the amount of hydropower available from Glen Canyon Dam. An unusual feature of the Glen Canyon power plant is the Kentucky bluegrass lawn occupying the crescent between the dam and hydroelectric plant. At the