SALT LAKE CITY — As groups and governments across seven states in the West grapple with how to best manage the ever-challenged resources of the Colorado River, scholars are calling for a science-based review of a study being carried out by the U.S. Bureau of Reclamation.

The scholars want the bureau's 2012 Colorado River Basin's Supply and Demand Study to get an analysis by the National Academy of Sciences that specifically probes key areas they assert aren't getting adequate attention.

In a letter sent Tuesday to Interior Secretary Sally Jewell, the scholars cite lack of information regarding groundwater depletion, flood management, water demand forecasts, ecology, water quality and climate change.

"If ever there was a time to undertake the first basinwide independent review of this vital natural resource, that time is now," said John Weisheit, conservation director of Living Rivers and Colorado Riverkeeper. "Decisions should be based on the best available information and the National Academy is well positioned to ensure that."

The letter's signatories include six faculty members from the University of Utah, among them Pat Shea and Dan McCool, who have argued for less diversions on the river and fewer water development projects.

The bureau's supply and demand study, initiated in 2010 and released at the end of 2012, addressed both current and future supply and demand imbalances on the river in light of growing populations, increasing urbanization and potential climate shifts.

An estimated 40 million people depend on the Colorado River for water supplies, a number that could nearly double to 76.5 million by 2060. By that time, the bureau projects the shortfall on the river could reach 3.2 million acre-feet, conservatively, or as much as 6.8 million acre-feet annually.

More than 150 study proposals were submitted to counter that shortfall, and the bureau is in the midst of another phase of implementing strategies that embrace environmental considerations, agricultural use, and municipal and industrial supplies.

The letter indicates that as this phase moves forward, there are key concerns that need to be addressed.

"Clearly (the Department of Interior) should seek the best available science for the management of this critical natural resource while taking a comprehensive look at the processes by which this important information will be integrated into Colorado River management."

As an example, the signatories to the letter say they are fearful there are supply options on the table that fail to adequately consider growing conservation trends throughout the basin states. The letter stressed the need to more fully understand stream flow forecasts in light of a changing climate and the vulnerability of the Colorado River system as a whole.

"The National Academy of Sciences, through its National Research Council, has assisted the (Department of Interior) in the past on several Colorado River management issues," the letter stated. "As scientists, we appreciate the peer review methods of the (National Academy of Sciences)."

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