Researchers studying the historic strain on water supplies in the American West have found a simple solution that could put parts of the Colorado River basin on a more sustainable path.

In a new paper published today, a consortium of scientists and water experts, including Julianne Quinn, assistant professor in the University of Virginia’s Department of Civil and Environmental Engineering, and Peter Debaere, professor at the UVA Darden School of Business, conclude that closing Colorado’s Free River Conditions gap should be an important first step in reducing water scarcity in the region.

In Colorado, if the river has enough water to meet everyone’s needs, everyone can take as much from the river as they want – regardless of whether they own water rights or not. This arrangement is a relic of the water-sharing agreements between the seven states, 25 Native American tribes and parts of Mexico – a total of about 40 million people – for whom the Colorado is a lifeline.

“Closing this gap in Colorado’s water rights system could save millions of cubic feet of water. This would be the state’s modest contribution to solving the water shortage in the Colorado River basin,” said Debaere, a water management and markets expert.

A region thirsting for solutions

Quinn leads the National Science Foundation project that conducted the analysis and specializes in optimizing water resource management through mathematical modeling to help water managers balance competing objectives.

“The goal of our project is to combine supply-side water management through the operation of reservoirs with demand-side management through fallow programs where farmers are paid not to irrigate their land,” Quinn said.

The article “Closing loopholes in water rights systems to save water: The Colorado River basin” appeared in the journal Water Resources Research, published by the American Geophysical Union (AGU).

The 2,330-kilometer-long Colorado River irrigates some of the country’s most productive farmland and generates hydroelectric power used in the Upper and Lower Basin states of Colorado, Wyoming, Utah and New Mexico, as well as Arizona, Nevada and California.

But the river’s water volume is shrinking as rising temperatures increase evaporation and the snowpack that feeds the river shrinks, while demand from farms and cities is increasing.

In mid-2022, water levels in the river’s two largest reservoirs, Powell and Mead lakes, dropped enough to jeopardize water withdrawals for hydropower, prompting a federal “shortage” declaration and the Biden administration’s call for reduced use. After the West experienced historic “atmospheric river storms” in 2023 and early 2024, the lakes have recovered to 37% of capacity. In 2000, they were nearly full.

The costs of “free flow conditions”

While trying to determine appropriate payments for a dormant program, the team discovered the Free River gap, Quinn explained.

“It jeopardizes the success of any payment program,” she said. “If the water ‘saved’ by paying farmers not to irrigate causes rivers to flow freely more often, someone else can legally divert the saved water, defeating the purpose.”

For example, when the river was free-flowing in 2017 – despite a decade and a half of drought – Quinn’s team estimated that 108 million cubic meters of water were diverted that could have been stored in Lake Powell.

In addition, the lower basin states have the right to issue a “compact call” if the upper basin states exceed their sharing commitments under the century-old Colorado River Compact. This could lead to sudden use restrictions and put those states, including Colorado, in a bind they could have avoided.

As some existing sharing agreements expire at the end of 2025, the seven states are renegotiating their rights to the Colorado River.

Debaere said closing the loophole was a small step but opened doors for future reforms.

“This is not a technological solution,” Quinn added, “but a pragmatic solution to closing a legal loophole in the management of water in the system.”

publication

Co-authors of the papers include T. Li (International Business School Suzhou, Xi’an Jiaotong-Liverpool University, Suzhou, China); S. Fox and K. Bennett (B3 Insight, Denver); P. Block and K. Hietpas (Department of Civil and Environmental Engineering, University of Wisconsin-Madison); M. Mekonnen and S. Sharma (Department of Civil, Design and Environmental Engineering, University of Alabama, Tuscaloosa, AL); B. Richter (Sustainable Waters, Crozet, VA; and S. Singh (Department of Systems and Information Engineering, UVA).

This article was edited by the Original version published by the UVA Darden School of Business.