Running Dry by 2021?

You need not go to the Middle East, North Africa or Southeast Asia, where there are already reported water shortages, to understand the value and scarcity of the life-giving liquid. Just look in America's own back yard. The American Southwest has been in a protracted drought for nearly a decade, with sinking water levels in lakes and rivers and decreasing snowpack in the mountains. And now a prominent scientist from the Scripps Institution of Oceanography at the University of California, San Diego, says that Lake Mead, which supplies water to 22 million people throughout the region, could be bone dry in just 13 years.

It may sound like the plot of an apocalyptic sci-fi flick, but Tim Barnett, a research marine geophysicist and climate expert at Scripps, says there's a 50 percent chance that the manmade lake, a reservoir created by Hoover Dam located on the Colorado River 30 miles southeast of Las Vegas, will be dry by 2021, or even sooner if climate changes continue as expected and water use is not curtailed.

Barnett, lead author of a paper titled "When Will Lake Mead Go Dry"which will appear in the peer-reviewed journal Water Resources Research, published by the American Geophysical Union, says human demand and human-induced climate change are creating a net deficit of nearly 1 million acre-feet of water per year from the Colorado River system, which includes Lake Mead and Lake Powell. Barnett talked to NEWSWEEK's Jamie Reno about the Lake Mead study, what it means for the Southwest, and what—if anything—can be done to save the lake. Excerpts:

NEWSWEEK: When and why did you begin the Lake Mead study?
Tim Barnett: We started in earnest at the beginning of last summer. It was a curiosity-driven project. I just wanted to find out if things were this bad, and we quickly concluded that they are … We were stunned at the magnitude of the problem and how fast it was moving. It's not a scientific abstraction. This will impact every person living in the Southwest.

How were you actually able to determine that the lake could run dry by 2021?
Our analysis of Federal Bureau of Reclamation records of past water demand and calculations of scheduled water allocations and climate conditions indicate that the system could run dry, even if mitigation measures are implemented. We started from the level it is today. We know how much water is coming in and how much will go out, to the farmers, to the cities, etc. We also know the rate of transfer to Mexico: 1.5 million acre-feet per year. The final thing we added, which the Bureau of Reclamation does not add in, were evaporation and infiltration into the soil, which is 1.7 million acre-feet per year. We added up all these numbers and put in the prorated amount from climate change, and found we had a negative number. We were stunned.

The Lake Mead/Lake Powell system is a source of water for millions of people throughout the Southwest. How many people would be directly affected if Lake Mead ran dry?
Thirty million people, or more. Everyone in Southern California, everyone in the entire region would be affected.