U.S. States Battle to Share Diminishing Colorado River Water Supplies

The Colorado River, which supplies 40 million people in seven U.S. states with potable water, is drying up, straining a water distribution treaty in the midst of the greatest drought in 1200 years, which is compounded by climate change.

California left the six states of Arizona, Colorado, Nevada, New Mexico, Utah, and Wyoming on Tuesday in response to a U.S. government deadline requiring them to negotiate their own supply cuts or face the possibility of federally mandated reductions.

Kevin Moran, a specialist in water policy at the Environmental Defense Fund, described today's events as a step forward.

"After twenty years of drought and the effects of climate change, six of the seven basin states are playing catch-up to minimize water use from the Colorado River," Moran told Reuters.

When the states signed its pact a century ago, the river was expected to produce 20 million acre-feet of water annually. An acre-foot (1,233 cubic meters) of water is sufficient to supply two urban households with water for one year.

The real flow has decreased to an average of 12.5 million acre-feet over the past two decades, leaving state water managers with more rights on paper than actual availability.

California receives the greatest allocation, of which 80 percent is utilized by its $50 billion agriculture sector.

Many experts believe that the state's choice to opt out of the deal increases the likelihood that the water dispute will reach the nation's top courts.

David Hayes, a lecturer at Stanford University Law School, stated, "We have a scenario where certain water rights holders in California say, 'We're not willing to give up additional water, and we believe we have legal rights and are willing to go to court if necessary.'"

"And there is insufficient time to fight these issues," Hayes, a former senior climate adviser to President Joe Biden, warned.

He identified the need for significant conservation efforts to safeguard reservoirs from overuse and drought exacerbated by climate change, a condition that, if left uncontrolled, might threaten water supply to Las Vegas or California from the Hoover Dam.

Although California was deluged for weeks beginning in late December by seven atmospheric rivers that dumped up to 30 inches (76 centimeters) of rain in some regions, the Colorado River basin received little of this precipitation.

California cannot resolve its long-term crisis without substantial investments to capture more storm water, repair flood plains, and recycle wastewater, despite forecasts of more such atmospheric rivers of increasing magnitude and frequency.

In at least 1,200 years, 2000-2021 was the driest 22-year period for southwestern North America, according to a paper published in Nature in 2017.

Sharon Megdal, director of the Water Resources Research Center at the University of Arizona, stated, "Something will have to give."

As temperatures rise, mountain snows melt more rapidly in the spring, and the state lacks the storage capacity to accommodate the runoff.

She noted that a letter signed by the six states demonstrated that they all acknowledged the need for a change in operating protocols for the Colorado River and its supplies.

"I believe that people would like to believe that we can find a way to keep these economic activities, our type of businesses, and our livelihoods going," Megdal added.