Seven states rely on water from the Colorado River for their residents, farms and industries. But a boom in population and development, particularly in the Southwest, has created even higher demand for that water, and an 11 year drought has siphoned off the supply.

“Its one of the most severe droughts that we've seen in the 100 or so years of record keeping,” says Terry Fulp, deputy regional director of the Bureau of Reclamation's Lower Colorado Region. (The Bureau manages the Colorado River and much of its infrastructure, including the Hoover Dam, on behalf of the states.)

To make matters worse, the water storage basins Lake Mead and Lake Powell, which were set up to stockpile water for this kind of drought, are depleted. Together, they contain only 58 percent of the water they were designed to hold. Visitors to the Hoover Dam can easily observe “bath tub” lines around Lake Mead, showing where the water line used to be. It’s a drop of more than 130 feet.