Arizona joins Nevada lawsuit over Colorado River cuts

Arizona has joined Nevada in a lawsuit challenging the federal government’s plan to drastically cut Lower Basin states’ share of Colorado River water.

The Arizona Department of Water Resources and Arizona Gov. Katie Hobbs announced Friday they filed a motion to intervene in a lawsuit filed by the state of Nevada in August challenging the U.S. Interior Department’s plan to impose mandatory water cuts in Nevada, Arizona, and California.

In August, the federal government finalized a new operating plan for the river that requires Arizona, California and Nevada to reduce their water use by 1.25 million acre-feet in both 2027 and 2028, more than twice the largest reductions required under the current guidelines that expire at the end of the year.  

Upper Basin states – Colorado, New Mexico, Wyoming and Utah – would not be subject to mandatory water reductions under the plan. 

Nevada Gov. Joe Lombardo welcomed Arizona’s decision to join the lawsuit, calling it “an important step in challenging a federal plan that unfairly burdens the Lower Basin and fails to require the Upper Basin to make meaningful reductions.”

“Nevada will not accept a framework that puts our water supply and the future of our communities at risk,” Lombardo said in a statement. 

Under the federal government’s plan, Nevada would have to give up 50,000 acre-feet of its Colorado River allocation over the next two years. An acre-foot is equal to 325,851 gallons — the amount of water needed to cover an acre of land a foot deep or enough water to supply two to three households for a year.

Additionally, Arizona would be required to reduce its water use by 760,000 acre-feet, while California will have to cut about 440,000 acre-feet under the plan.

But if conditions worsen, Nevada could have its 300,000 acre-foot Colorado River entitlement cut by more than 213,000 acre-feet or about 71% of its allocation. Nevada already has the smallest allocation of Colorado River water among the three Lower Basin states. 

In a statement, Hobbs called the proposed cuts “draconian” and said Arizona “will not accept a forced federal plan that solves this crisis on the backs of our families, farmers, and businesses.”

Nevada filed the lawsuit three days after the Trump administration released its 10-year plan for managing the Colorado River, and the nation’s two largest reservoirs, Lake Powell and Lake Mead, amid ongoing drought and record low water storage.

Tom Buschatzke, director of the Arizona Department of Water Resources, said in a statement that “Intervention in the Nevada lawsuit is necessary at this time for Arizona to protect its legal rights to Colorado River water while preserving a path forward to achieving a collaborative outcome with California and Nevada to protect the Colorado River system.”

John Entsminger, general manager of the Southern Nevada Water Authority, echoed that criticism saying that “Like Nevada, Arizona recognizes significant flaws in the federal government’s Environmental Impact Statement and the National Environmental Policy Act process used to develop the framework for post-2026 Colorado River operations.”

Lower Basin states have argued that the Upper Basin should be required to share mandatory water cuts in order to spare downstream states from taking steeper cuts. Upper Basin states argue they don’t have the infrastructure to store water during dry years like Lower Basin states, and are already restricted by available supply every year.