Arizona is bone dry, desiccated by the worst drought ever seen in the state's 110-year long observational record. The Grand Canyon State has been in drought conditions for a decade, and researchers think the dry spell could hold out for another 20 to 30 years, says the City of Phoenix.

That people have not been fleeing Arizona in droves, as they did from the plains during the 1930s Dust Bowl, is a miracle of hydrological engineering. But the magic won't last, and if things don't start to change Arizona is going to be in trouble fast, says the New York Times.

A quarter of Arizona's water comes from the Colorado River, and that river is running low. There's not enough water in the basin to keep Arizona's crucial Lake Mead reservoirs topped up. If changes aren't made to the entire multi-state hydrological system, says the Times, things could get bad.

If upstream states continue to be unable to make up the shortage, Lake Mead, whose surface is now about 1,085 feet above sea level, will drop to 1,000 feet by 2020. Under present conditions, that would cut off most of Las Vegas’s water supply and much of Arizona’s. Phoenix gets about half its water from Lake Mead, and Tucson nearly all of its.

Aside from the Colorado and other rivers, Arizona does get about 44 percent of its water from groundwater. As a fall-back, some cities have already turned to pumping this water out of the ground. Yet groundwater is only renewable to an extent, so relying on it long term is not a real solution.

Even if the current problems can be solved, though, that doesn't mean Arizona will be free of water-related woes. According to the Environmental Protection Agency, climate change is going to make everything worse.

Warming has already contributed to decreases in spring snowpack and Colorado River flows, which are an important source of water for the region. Future warming is projected to produce more severe droughts in the region, with further reductions in water supplies. Future water scarcity will be compounded by the region's rapid population growth, which is the highest in the nation.

Arizona already has projects set up to recycle waste water, and they're looking to squeeze even more out of every drop. But that doesn't stop the fact that climate change and the prolonged drought have cut their upstream supply.