Climate change, drought to strain Colorado River

Seven Western states will face more water shortages in the years ahead as climate change exacerbates the strains drought and a growing population have put on the Colorado River, scientists say.

"Clearly we're on a collision course between supply and demand," said Brad Udall, director of the Western Water Assessment at the University of Colorado.

Although there is some disagreement about when the most dire conditions will materialize, scientists at a conference in Salt Lake City said Thursday they expect less water to be available in the coming decades.

Without fundamental shifts in water management, the result will be shortages and difficult decisions about who in the seven states the river serves will get water and who will go without, said Dave Wegner, science director for the Glen Canyon Institute, which organized the one-day conference at the University of Utah.

"To me, it's not going to be a pretty debate," Wegner said.

The changes are already being seen in reduced water flows, higher air temperatures and an unrelenting demand on the Colorado, which snakes across more than 1,400 miles (2,252 kilometers) and provides water for farms, businesses, cities and homes. The river serves an area where 30 million people live, in Arizona, California, Colorado, Nevada, New Mexico, Wyoming and Utah.

Last year, officials from the seven states and Interior Secretary Dirk Kempthorne signed a far-reaching agreement aimed at conserving and sharing scarce Colorado River water. The 20-year plan formalized rules for cooperating during the ongoing drought.

A study released in February by the Scripps Institution of Oceanography in San Diego said there's a 50 percent chance that Lake Mead, which straddles the Arizona-Nevada state line, could run dry by 2021.

Several models by different groups of scientists have made predictions about the future flow of the Colorado; all of them predict less water, said Tim Barnett, one of the Scripps study's authors. The prospect of warming temperatures only increases the strain on an already strained system, he said.

"The current usage is simply not sustainable," Barnett said.

Udall quibbled with Barnett's predictions about 2021 but not the overall prediction that water in the Colorado River basin will become more scarce.

"It's a question of when," he said.