The Hoover Dam

Under current conditions and according to models predicting future climate change, the water supply from the Colorado River system is not sustainable, says a recent study.

“Scheduled deliveries of water from Lake Mead, created by Hoover Dam, could be missed 60 to 90 percent of the time by midcentury if human-caused climate change continues to make the region drier,” said research marine physicist Tim Barnett, of the Scripps Institution of Oceanography at the University of California, San Diego.

The Colorado River supplies water to 27 million users in seven states and two countries and irrigates more than 3 million acres of farmland. The Colorado River system drains 242,000 square miles, or about one-twelfth of the continental U.S.

Barnett’s study asks whether the river can deliver water at the levels currently scheduled if the climate changes as models predict. “The answer is no,” he said.

Barnett told Homeland1 what’s even more frightening is that nobody has talked about this until his paper, which appeared in the April 20 edition of the journal Proceedings of the National Academy of Sciences.

“People knew this could happen 30 years ago, but few have paid any attention to it,” he said. “We think it’s time for them to do that.”

Even under conservative climate change scenarios, Barnett found that reductions in snow melt that feeds the Colorado River mean that it could short the Southwest of a half-billion cubic meters (400,000 acre-feet) of water per year 40 percent of the time by 2025. An acre-foot of water is adequate to meet the annual water needs of two suburban households.

By the later part of this century, according to the model, those shortages double, Barnett said.

Can anything be done?

Conservation and water reclamation help, but they are mitigators, not panaceas. Las Vegas already reclaims 60–70 percent of its water.

“The Las Vegas model won’t work as well in California, because about 80 percent of the water taken out of the river in the lower basin goes for agriculture,” Barnett said.

Barnett said the various users of river water need to find a way to reduce average deliveries. That would be an interesting trick, since desert cities like Phoenix, Tucson, Palm Springs and Las Vegas all continue to expand.

“The flow in the Colorado River is fixed, so where are they going to get water?” Barnett wonders.