http://www.newsweek.com/what-will-happen-las-vegas-if-lake-mead-water-level-gets-too-low-1773985

As Lake Mead's water levels continue to decline, nearby cities like Las Vegas could be in trouble.

Lake Mead is the largest man-made reservoir in the U.S., spread between Nevada and Arizona on the Colorado River. It is formed by the Hoover Dam, which produces about 4 billion kilowatt-hours of hydroelectric power every year. It serves over a million people living across Nevada, Arizona, and California