SCOTTSDALE, Ariz. — There’s a less than 5 percent chance that Lake Mead, one of the nation’s largest reservoirs, could dry up by 2021, contradicting a study earlier this year predicting a more dire possibility, according to research presented Tuesday in Scottsdale.
The research, conducted by scientists at the University of Colorado, was presented at a Colorado River symposium at a Scottsdale resort. The findings are expected to be published sometime next year.
Lake Mead is one of several large reservoirs on the Colorado River that holds drinking and irrigation water for millions of people in western states.
A study released in February said there’s a 50 percent chance that climate change would leave Lake Mead dry by 2021. The study, conducted by the San Diego’s Scripps Institution of Oceanography, stunned water managers in the West, with one calling it absurd.
The more recent research shows there’s less than a 5 percent chance that the lake will dry up by 2021, and a 40 percent chance it will go dry in any given year after 2050.
The Las Vegas Valley gets 90 percent of its drinking water from Lake Mead.
J.C. Davis, spokesman for the Southern Nevada Water Authority, said the latest projections for the reservoir should come as no surprise to water managers in the region.
“There is a broad spectrum of climate models out there. That’s what makes our job so challenging,” Davis said. “But we like their optimism.”
Maybe optimism is the wrong word. Although they came up with different numbers, the scientists who conducted the conflicting research agree that Lake Mead is in trouble.
“The risk is not zero and it’s not even at 1 percent or 2 percent, and that should give people some pause,” said Bradley Udall, director of the University of Colorado Western Water Assessment and co-author of the recent findings. “Even a 5 percent chance of a dry reservoir in any one year, it’s significant, and 20 percent is very, very high, and 40 percent is off the charts with regard to making a reliable water system.”
Tim Barnett, a research marine physicist at the Scripps institution and co-author of the study released in February, said he did not make any errors in conducting his research, but that’s beside the point.
“The point is, whether it’s 40 percent in 2050 or 40 percent by 2030, that’s a hell of a problem,” he said. “The main factor is we’re taking more water out of the system than Mother Nature is putting in. And as long as that’s true, you can tell what’s going to happen.
“You don’t have to be a rocket scientist.”
In December, seven western states and Interior Secretary Dirk Kempthorne signed an agreement to conserve and share scarce water if the Colorado River drought continues.
The agreement established triggers that would reduce river water deliveries to states if the lake’s water level falls to 1,075 feet above sea level. It also calls for states to create agreements for further restrictions if the level drops to 1,025 feet.
The lake is currently half full at 1,107 feet.
Las Vegas Review-Journal writer Henry Brean contributed to this report.