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Scientists see higher demand for scarce water as inevitable

SALT LAKE CITY — Drought, climate change and a growing population in the West are pushing the Colorado River basin toward deep trouble in the coming decades, scientists said last week.

“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.

Despite some disagreement about when the most dire conditions will materialize, scientists at a conference Thursday in Salt Lake City said 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. The institute organized the one-day conference at the University of Utah called “Adjusting to Less Water: Climate Change and the Colorado River.”

“To me, it’s not going to be a pretty debate,” Wegner said.

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 and serves about 30 million people in Nevada, Arizona, California, Colorado, New Mexico, Wyoming and Utah.

The Las Vegas Valley gets 90 percent of its drinking water from the Colorado by way of Lake Mead.

Tim Barnett, a scientist with Scripps Institution of Oceanography in San Diego, was one of the authors of a study released in February saying there’s a 50 percent chance Lake Mead could run dry by 2021.

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

Several models by different scientists have made predictions about the Colorado’s future flow. All predict less water, Barnett said. The prospect of warming temperatures only exacerbates the strain on a strained system, he said.

“The current usage is simply not sustainable,” he said.

Udall quibbled with Barnett’s predictions about 2021 but not the prediction that water in the Colorado River basin will become more scarce. “It’s a question of when,” he said.

Even if the West’s climate doesn’t get as warm as predicted, the river system will likely be faced with shortages, said Gregory McCabe, a project chief at the U.S. Geological Survey’s water resources division in Denver.

He said building more reservoirs probably won’t be enough to mitigate changes to the system, especially warming temperatures.

One of the best approaches will be to drive down demand by finding more ways to conserve water, McCabe said.

The Colorado has been the source of controversy as states fight for their share.

As luck would have it, the 20th century was one of the wettest going back several centuries. But it shouldn’t be assumed that water levels will remain as plentiful in the future, researchers said.

Connie Woodhouse, a University of Arizona scientist, said tree rings indicate the amount of moisture has fluctuated widely over hundreds of years, but has tended to be drier than in the last 100 years.

It’s time to consider a “new normal” for shrinking water supplies in the Colorado River basin, Wegner said. That will require a re-evaluation of allocations, use, conservation, dams and legal obligations.

“We need to look at every part of the water management system out there.”

Review-Journal writer Henry Brean contributed to this report.

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