Residents of the western U.S. could be in for droughts worse than they have ever seen, a blue ribbon panel warned today. The severe, recurrent droughts that parched the region in past centuries could strike again--and could even be exacerbated by a regional warming trend.
Much of the western U.S. was gripped by drought from 2002 to 2005. During these years, water flow in the Colorado River--which supplies tens of millions of people in seven states--dropped to as low as a quarter of its usual value. That crisis spurred several federal and state water agencies to ask the National Academy of Science's National Research Council (NRC) to examine the state of science on the future of the river's water.
The committee appointed by the NRC, chaired by civil engineer Ernest Smerdon of the University of Arizona, Tucson, took a hard look at climate records. In particular, it examined what is known about the river's history from tree rings, the width of which indicates how much moisture was available at the time. According to those records, the average annual flow has fluctuated much more in past centuries than it did during the last century, suggesting that the droughts also were more extreme. "These events will happen again, and we'd better be prepared," Smerdon said at press conference this morning.
The committee warned that conservation efforts aren't likely to meet the growing demand for water in the west, pointing out that Arizona's population has increased about 40% since 1990, while water consumption in Clark County, Nevada, (including Las Vegas) doubled from 1985 to 2000. Another complication is climate change, which has been warming the region and will likely continue to do so. Higher temperatures could mean less water in the Colorado River, as more water evaporates, for example. The situation will "inevitably lead to increasingly costly, controversial, and unavoidable trade-offs," the panel found.
How to prepare for the future droughts is a conundrum. The committee offered no solutions, but it did call for a large, federally funded study of urban water use and issues to help planners and managers cope with the problem.
"We're all recognizing that there are limits to the water we've been using," says Tony Willardson, Deputy Director of the Western States Water Council in Midvale, Utah.