Water from the Colorado River sustains nearly 40 million people across seven Western states — and a legal fight over who gets to keep how much of it is intensifying fast. Arizona and Nevada have now taken their grievances to federal court, and the outcome could reshape water policy across the American West for decades.
The Arizona Department of Water Resources filed a motion to intervene in Nevada’s existing lawsuit against the federal government over its new Colorado River management plan. The Central Arizona Project — which operates a 336-mile canal delivering Colorado River water to the Phoenix and Tucson areas — did the same less than two weeks later. Together, the moves mark a significant escalation in a long-running and increasingly contentious dispute over how to divide a river that is shrinking due to drought and climate change.
At the center of the conflict is a federal plan that gives the Interior Department authority to cut Colorado River water supplies to Arizona, California, and Nevada — the three Lower Basin states — by up to 40% per year. Arizona would take the hardest hit. State officials have been quick to call that plan unfair, and now they’re arguing it’s also illegal.
Arizona’s top water official, Tom Buschatzke, said the plan would “devastate” Arizona’s economy and “ignores basic elements of the law of the river.”
Brenda Burman, general manager of the Central Arizona Project, added:
“It fails to adequately assess the devastation, the economic harm, the harm to everyday communities, the harm to the canal itself. There were many problems there.”
How the States Got Here
The seven states that rely on Colorado River water spent years in closed-door meetings trying to hammer out a shared plan for reducing water use as the river’s flows declined. The Lower Basin states — Arizona, California, and Nevada — proposed voluntary cutbacks. The Upper Basin states — Colorado, New Mexico, Utah, and Wyoming — pushed back, arguing they are already cutting back because they receive less snowmelt but are still required by law to send a fixed amount of water downstream.
Talks blew through major deadlines with no agreement reached. With states at a standstill, the federal government reluctantly came up with its own plan — one that imposed new cutbacks only on the Lower Basin, leaving the Upper Basin untouched.
Arizona and Nevada’s lawsuit argues that federal authorities were legally required to fully assess the environmental and economic harm caused by water cuts of this scale for millions of people and major industries before finalizing its plans for cutting back water use. They want the Interior Department to start over with a new plan that more evenly distributes reductions across the region.
Cynthia Campbell, a longtime water lawyer and former water advisor for the City of Phoenix, summed up the immediate goal plainly:
“What they’re looking for is they want it redone. And I suppose Nevada believes that if that happens, there might be a different outcome.”
The Bigger Threat Lurking Behind the Lawsuit
But getting the plan redone isn’t the only thing Arizona is after. Embedded in the legal filing is a more sweeping argument: that the Upper Basin states are violating the foundational 1922 Colorado River Compact, which has governed water rights on the river for more than a century. By putting that argument in writing now, Arizona is signaling it may be preparing to take one or more Upper Basin states directly to the U.S. Supreme Court.
Water policy experts overwhelmingly agree that a Supreme Court showdown would not be a good way to resolve Colorado River disputes — but the possibility is becoming harder to dismiss.
Elizabeth Koebele, an associate professor at the University of Nevada, Reno who specializes in water policy, has described that potential case as “the nuclear option.” She sees the current lawsuit as a way for states to begin laying the groundwork.
“I kind of see it as almost like a low-hanging fruit option to get some of those quote-unquote complaints, concerns, evidence, different perspectives on the table,”
Koebele said.
“For that reason, it makes sense that Arizona jumped on board.”
Buschatzke said Arizona tried hard to avoid legal action, but felt it had no other choice given the scale of the proposed cuts.
“An outcome in which that burden falls on the Lower Basin and specifically on Arizona is an unacceptable outcome,”
he said.
“And while we tried for almost four years to find a collaborative path forward with the Upper Basin, that didn’t happen.”
There is a slim hope the lawsuit could push all seven states back to the negotiating table. If states manage to craft their own agreement, the federal plan could be scrapped entirely — and no one would need to go to the Supreme Court. But Koebele is skeptical that will happen.
“I’m really pessimistic about that happening,”
she said.
“Just based on how slow and how conflictual the process was over the last five years.”
Nevada’s lead negotiator, John Entsminger, said in an interview with 8 News Now in Las Vegas that the new lawsuit “made things a little more tense” in multi-state talks, while also suggesting states are “maybe 70%” of the way to a deal.
“Major strides have been made. Significant agreements on how to operate the system have been agreed upon, but as with almost any negotiation at any human enterprise, it’s that last 10 percent that hold you up, right?”
Why a Supreme Court Fight Would Be Costly — in Every Sense
James Eklund, a water lawyer who served as Colorado’s top negotiator from 2013 to 2019, urged states to think carefully before going down the path of state-versus-state litigation. He laid out three major concerns.
The first is cost. Arizona lawmakers recently boosted the state’s Colorado River litigation fund to $9 million — but Eklund said that’s a fraction of what a prolonged Supreme Court battle would actually require.
“It would shape up to be a very expensive proposition to wage war in this way,”
he said.
The second concern is time. Other major water disputes offer a sobering preview: a dispute over water in Texas v. New Mexico and Colorado took 13 years to resolve. Kansas’s case against Colorado over the Arkansas River, filed in 1985, wasn’t settled until 2009. A Colorado River case would be even more complex, given that the river touches seven states, 30 federally recognized Native American tribes, and the country of Mexico.
“We don’t have that time,”
Eklund said.
“We don’t have two years, we barely have two months. We need to be managing a river right now, and it’s just not acceptable. It’s just a failure, and there’s no other real way to put it, if we end up waiting decades for resolution of these issues.”
Third, even after years in court, a Supreme Court ruling would not produce a comprehensive water management plan. It would answer specific legal questions, but leave the deeper problem of how to share a shrinking river largely unresolved.
“The Supreme Court will not answer everything to everyone’s satisfaction and put the whole question of the Colorado River management to bed,”
Eklund said.
“You’re not going to get what I think most people would want, what most Americans would want, which is just — tell us what the plan is.”
Still, Eklund held out hope that a court battle can be avoided.
“The question isn’t whether those states have legitimate legal disagreements. They do,”
he said.
“The question is whether we have the political courage and creativity to resolve the practical problem before we spend the next decade or decades litigating it. I believe we do. I’m an optimist on this.”
What Comes Next
Even the existing Nevada lawsuit — far less complicated than a full Supreme Court battle — is unlikely to produce quick results. The federal government has already filed a request for an extension until December 10 to respond to Nevada’s initial complaint, meaning significant court activity probably won’t occur for months.
Interior Secretary Doug Burgum pushed back on Arizona’s decision to join the suit. In an interview with Tucson news station KOLD, he said
“litigation doesn’t create more water”
and warned:
“If this thing ends up in court that would be a bad deal for Arizona. We believe that the Governor is wrong on this topic.”
Campbell noted that the Nevada lawsuit asks for a redo of the Interior Department’s 10-year river plan, but does not request an immediate pause on the current rules while the case proceeds.
“It does ask for a stop, but it’s not like a stop in the next couple months,”
she said.
“How long that takes to work through that — to get a court to address that issue of whether or not there are grounds for an injunction — that could take a little bit of time. How much time? Well, it’s hard to say.”
Meanwhile, the cities, farms, and businesses that depend on Colorado River water face mounting uncertainty. A separate side deal between the states appears to have stalled, leaving open questions about exactly how much water each state will be able to draw from the river as soon as 2027. The Lower Basin states have been working on a separate agreement among themselves to more evenly share the burden of cutbacks — sparing Arizona from bearing the brunt alone — but the process of determining which cities and farms specifically will use less water has slowed that effort.
About a month ago, Buschatzke told KJZZ that Arizona and Nevada have plans in place, and that California is “working out final details” on how to cut enough water across some of its largest users.
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