A series of drastic consumption cuts and difficult management decisions will be necessary to stabilize the Colorado River system amid a 23-year-long “Millennium Drought,” regional experts argue in a new policy paper.
The paper, published in Science on Thursday, dissects how lawmakers and agency administrators might save a cross-border resource that supplies water to more than 40 million people and irrigates nearly 5.7 million acres of agriculture.
Stabilizing the system could occur by accelerating certain policy changes that right now might “seem like a political impossibility” but could become inevitable if current conditions continue, the authors state.
Scientists expect that by the end of this year, the combined storage of Lake Powell and Lake Mead — the two largest reservoirs in the U.S., which are fed by the river — will plunge to 25 percent of their capacity due to the combined effects of climate change and mismanagement.
Only 10 percent of the Colorado River’s natural flow, which is diverted entirely along its 1,400-mile course, now reaches Mexico, and rarely does the river ever get to the ocean, the authors noted in a statement accompanying their paper.
But realizing a wetter future for the Colorado River system would require upending years of ingrained policy: rethinking the “institutional and political divisions” that have defined the so-called “Law of the River” and dictated water allocations for decades, according to the authors.
“Although current policies are inadequate to stabilize the Colorado river if the Millennium Drought continues, various consumptive use strategies can stabilize the system,” the researchers, from Utah State University, Colorado State University and the University of Oxford, said in a statement.
“However, these measures must be applied swiftly,” they continued. “Although these concessions by both basins may seem unthinkable at present, they will be necessary if recent conditions persist.”
Today, the Colorado River system is divided into Upper and Lower basins, the former of which includes Colorado, New Mexico, Utah and Wyoming, and the latter of which includes Arizona, Nevada and California.
For 100 years, the authors explained, the Law of the River has governed the system’s management — comprised of interstate compacts, a binational treaty and relevant amendments. But the law is not set in stone and has been revised over the years.
Nonetheless, as the Millennium Drought becomes the “new normal,” researchers warn that an incremental approach to adaption is no longer practical.
“The risks of drought and climate change are both uncertain and potentially severe,” the authors wrote in an executive summary of their 90-page paper. “However, our ability to control these futures is extremely limited compared to our ability to control the future demands for water.”
Modeling 100 potential scenarios and management strategies, the authors determined that dramatic steps must be taken to stabilize the river’s resources, including changing measuring strategies and tactics.
Researchers cast doubt on projections indicating a significant increase in consumption in the Upper Basin, calling them “unrealistically high.” Water use in the upper region has remained essentially unchanged since 1988, and no such forecasts exist for the Lower Basin.
Water-supply management plans based on such increased use therefore both “mislead the public about the magnitude of the impending water supply crisis and make identifying solutions to an already difficult problem even harder,” the researchers contended.
Today, cuts in water use in the Lower Basin occur when Lake Mead declines to certain elevations, while the amount of water released from Lake Powell depends on the elevations of both reservoirs.
The researchers maintain that the current approach clouds the public’s perception of water conditions and “convolutes management responses to critical situations.”
Moving forward, authors suggested using the combined storage contents of Lake Powell and Lake Mead as the primary metric for water management in the Colorado River.
Their proposed metric would reveal “status of the actual resource being managed — the stored water supply,” according to the paper.
But implementing such a measure, the researchers acknowledged, would challenge both historic compact obligations and existing divisions between Upper and Lower basin states.
A stable path forward would also require increased limitations on Upper Basin water use, as well as significantly larger Lower Basin reductions in supply, the authors noted.
“The Colorado River can be sustainably managed only if consumptive water uses are matched to available supplies,” they said.
Such a shift, however, would require “aggressive commitments to water conservation by both the Upper and Lower Basins, according to the paper.
“The Law of the River will need to be adapted more dynamically than ever before,” the authors added.