On a particularly frightening note, a Climate Central article written July 13, 2011, by Tom Yulsman (climatecentral.org), pointed out that for the first time withdrawals from the Colorado River outpaced supply and future water consumption is likely to continue this desperate trend.
The Colorado River supplies water to almost 35 million people in 7 states including Arizona. The shortfall has been made up through increasing draws from Gen Canyon and Mead Reservoirs. The reservoirs, however, are having problems of their own. Facing a "worst case scenario" the reservoirs are going through an 11 year drought, the worst in recorded history.
This shortfall is occurring despite a snowpack of huge proportions this year in the Colorado Rockies which is the primary supplier to the river.
It's also occurring in the face of decreased per capita use in the Colorado Basin. In a study measuring use over 20 years it found that while the per capita use dropped a whopping 20% ... the total people using water from the Colorado River grew by 10 million.
As their study concludes, this is unsustainable.