If it dries up, so could power and water for much of the Southwest.
Lake Mead stores water from the Colorado River. When full, it holds 9.3 trillion gallons, an amount equal to the water that flows through the Colorado River in two years. The water from Lake Mead is used for many things. It irrigates a million acres of crops in the United States and Mexico, and supplies water to tens of millions of people. Its mighty Hoover Dam generates enough electricity to power a half-million homes. Additionally, the power from Hoover Dam is used to carry water up and across the Sierra Nevada Mountains on its way to Southern California.
In 2000, the water level at Lake Mead was 1,214 feet, close to its all-time high. It's been dropping ever since. When Lake Mead was built during the 1920s and 1930s, the western United States was enjoying one of the wettest periods of the past 1,200 years. Even today, our so-called drought is still wetter than the average precipitation for the area averaged over centuries. In other words, for the last 75 years, we've been partying like it's 1929. Farmers grow rice by flooding arid farmland with water from Lake Mead; residents of desert communities maintain front lawns of green grass; golfers demand courses in areas where the temperature exceeds 100 degrees Fahrenheit during the summer.
And it continues to shrink. Lake Mead's water level fell 14 feet last year, and the Bureau of Reclamation has projected the level will drop 14 more feet this summer. That will bring it perilously close to 1,075 feet, the point at which the federal government can step in and declare a drought condition, forcing a reduction of 400,000 acre-feet drawn from Lake Mead per year. A typical Las Vegas home uses a half acre-foot of water per year, so such a reduction would be equal to turning the tap off for 800,000 households.
In 2008, the Scripps Institute of Oceanography issued a paper titled "When will Lake Mead go dry?" which set the odds of Lake Mead drying up by 2021 at 50-50. No more water, no more electricity, no more pumping power.