PHOENIX - Changes in climate and strong demand for Colorado River water could drain Lake Mead by 2021, triggering severe shortages across the region, scientists said in an unusually bleak water-supply outlook.
Scientists working at San Diego's Scripps Institution of Oceanography said Tuesday the West's largest storage reservoir faces increasing threats from a combination of factors including human-induced climate change, growing populations and natural forces like drought and evaporation.
A dried up Lake Mead would be a disaster for Arizona and Nevada.
When water levels dropped below 1,000 feet in elevation, Nevada would lose access to all its river allocation. Arizona would lose much of the water that flows through the Central Arizona Project canal. Power production also would cease before the lake level reached bottom, researchers said.
There is a 50 percent chance Lake Mead will run dry by 2021 and a 10 percent chance it will run out of usable water by 2014, if the drought deepens and water use climbs, researchers said.
"We were stunned at the magnitude of the problem and how fast it was coming at us," said marine physicist Tim Barnett, who co-authored a paper examining the fate of Lake Mead. "Make no mistake, this water problem is not a scientific abstraction but rather one that will impact each and every one of us that live in the Southwest."
Lakes Mead and Powell help manage water resources for more than 25 million people in the seven states, including Arizona, that rely on the Colorado River for water and power.
The two huge reservoirs have been studied in recent years using numerous hydrology models, but none forecast a dry Lake Mead within 15 years.
"We did a lot of studies, and none of them ever made Lake Mead go dry, period, end of story. We looked 100 years out, and Lake Mead never went dry," said Larry Dozier, deputy general manager of the Central Arizona Project.
Dozier had not seen the Scripps study but worked closely on other models that have produced different results.
"We did what we called our worst case, and it just didn't happen," he said.
Currently, Lake Mead is half-full, as is Lake Powell.