Scientists have now said that whether or not Lake Mead exists in 15 years is a coin toss:

Based on models constructed from the analysis of historical records from the Federal Bureau of Land Reclamation, the researchers, Tim Barnett and David Pierce, say there is a ten percent chance the reservoir will be dry in 2014, and a 50 percent chance no water will be left by 2021.

Lake Mead was created by the Hoover Dam’s blockage of the Colorado River. The river is fed by snow pack from Rockies, which has been decreasing. The dam, of course, was one of the prototypical megaengineering efforts of the 20th century and a symbol of how human ingenuity could conquer any obstacle, including supplying water to a city the size of Las Vegas in the middle of the desert.

But the sheer amount of water that natural and manmade climate changes and human usage is drawing out of the Colorado River system is staggering. The researchers estimate that 1 million acre-feet, or 326 billion gallons, of water are being leached out of the system each year. They say that’s enough to supply 8 million people.

While this sort of story is sensational, I think it’s more than a little alarmist.  For one thing,  it ignores the springs that initially brought settlers to the Las Vegas Valley — by the way, while you are in Vegas you can check this out for yourself at the Springs Preserve.  For another, they specifically say that the current quantity of water taken out of the system would supply a city the size of New York City when Las Vegas only has a population of half a million people — the entire valley has a population of maybe 2 million. Even if all our roughly 125,000 hotel rooms were occupied, and all 42,000 additional rooms scheduled to be available by 2012 were occupied, and all the people who will be employed as a result of those rooms were counted, there would still be far fewer than 8 million people in the valley.

Los Angeles, on the other hand, may want to think about desalination.