The photos below are from Lake Mead National Recreation Area, Nevada, USA: Three desert ecosystems meet in Lake Mead NRA: Mojave Desert, Great Basin Desert, and Sonoran Desert. Formation of Lake Mead began in 1935, less than a year before Hoover Dam was completed along the Colorado River. The area surrounding Lake Mead was established as the Boulder Dam Recreation Area in 1936. In 1964, the area was expanded and became the first National Recreation Area established by US Congress.