For more than a century, the Colorado River Compact has been the legal force setting up allocations of river water that persist even though all parties now realize the seven river basin states were promised for more water than the river normally carries.
But now, as drought and climate change have slashed flows in the already over-allocated river, the states including Arizona are getting “too close for comfort” to reaching what two river experts call a “Colorado River Compact tripwire.”
Simply put, in a few years the four Upper Basin states may no longer meet their legal obligations to deliver river water to the three Lower Basin states, including Arizona, say the two researchers, Eric Kuhn and John Fleck.
The concern arises as the seven states appear likely not to reach a federal goal of agreeing to a comprehensive, long-term settlement by the end of March on how to curb overuse of the river water.
If the states fail to reach agreement, it raises a possibility previously seen as unthinkable — a legal conflict over what the 1922 compact requires for delivery of water to the Lower Basin.
Divvying up water rights, the compact gave the Upper Basin states 7.5 million acre-feet, the Lower Basin states up to 8.5 million, and Mexico another 1.5 million.
Now, the U.S. Bureau of Reclamation wants to start analyzing by March how to cut water use, but it first wants the states to come up with their own proposal. That’s for an environmental review to help set new guidelines for how the river will be managed once the current guidelines expire at the end of 2026. The guidelines from 2007 are now universally called inadequate to deal with the Colorado’s continually declining flows.
But the Upper and Lower Basin states are so far from agreement on a seven-state plan that they’re now preparing separate plans.
“Given the complexity of the challenges and the short amount of time for an initial submittal, it is possible that a consensus 7-state alternative may not be achieved within the next month,” the Upper Basin states said in a joint statement.
After the initial submission, the Upper Basin states hope to work with Lower Basin states ""to refine the two basin alternatives into a single consensus alternative," the statement said.
Jeffrey Kightlinger, former general manager of a six-county Southern California water district, agreed a seven-state pact by March is unlikely although one could be reached by December.
But “I think the Lower Basin is very close to coming up with agreement among themselves on how it should be managed,” said Kightlinger, who consults for Southern California’s Imperial Irrigation District west of Yuma but said these comments represent only his views.
Many state officials, water researchers and legal experts have said an agreement is critical to avoid a protracted legal fight over the compact. Litigation, they say, could paralyze management of the river for years.
But in a blog post last month, Fleck and Kuhn noted that while the states agree the compact should be the foundation of a seven-state agreement, they can’t even agree on how much water the compact requires the Upper Basin states to deliver from Lake Powell to Lake Mead in the Lower Basin.
If the Upper Basin can’t meet its delivery obligations, the concern is that the Lower Basin states would put forth a “compact call.” That would try to force the Upper Basin to curtail its river water use, through litigation if necessary.
The compact is part of the Law of the River, a collection of laws, regulations, court rulings and historical precedents governing river operations, which the seven states also say should be a foundation for their ultimate agreement.
“The states agree that the Law of the River has to be the basis of what we do, but don’t agree on what the Law of the River actually says. Without an agreement on this fundamental issue, calling the 1922 Compact a foundation is nothing more than self-delusional wishful thinking,” Kuhn and Fleck wrote.
Who should take the cuts?
Today, the Lower Basin states have committed to conserving enough water to eliminate the river’s structural deficit. It represents a gap between water supply and demand that most experts have agreed would exist even if human-caused climate change hadn’t helped slash annual river flows 20% since 2000.
The Colorado River below Glen Canyon Dam from the Glen Canyon Dam Bridge, Page, Arizona, in May 2022.
Different parties have estimated the structural deficit’s size at 1.2 million, 1.5 million or 2 million acre-feet or more. The lower numbers aren’t far from what the bureau recently estimated in a new study is the amount of water the river loses annually to evaporation below Hoover Dam.
Since evaporation loss has never been compensated for by water users before, saving that much water would be considered a major accomplishment.
But most researchers and government officials agree that if the river continues its current “aridification,” or drying due to increased temperatures, more cuts will be needed. That’s where the disagreements start.
Upper Basin officials, led by Colorado River Commissioner for Colorado Becky Mitchell, won’t yet commit to water use reductions. That’s partly because Upper Basin states use much less river water every year than Lower Basin states. They say they welcome the Lower Basin’s willingness to tackle the structural deficit but want more details on how those cuts will be parceled out.
As those states’ officials see it, Upper Colorado Basin users already take regular cutbacks, losing some of their allocated river supplies in many years due to natural shortages on the river’s tributaries. That’s where many farmers there get river water.
By contrast, Arizona and other Lower Basin states’ supplies are stored in reservoirs and are delivered in amounts set by contract. Upper Basin supplies vary yearly, based on how much melted snow flows down tributaries.
“Upper division states are willing to do our part. We’re willing to conserve water in ways that work for water users,” Mitchell said on a public webinar Colorado officials organized on Feb. 15. “But folks across the basin need to understand that our own users don’t have certainty of supply. They (often) get less than what they need.
“This is how it goes when you rely on snowpack instead of reservoirs. We can’t expect certainty for others when we don’t have certainty ourselves,” Mitchell said. “We have not had the benefit of knowing exactly what we are gong to get the following year.”
She also said Lower Basin state officials have sought a reduction in Upper Basin usage to match whatever the Lower Basin agrees to cut.
“You’ve probably heard lower basin states call for a 1 to 1 reduction. That’s not possible in the Upper Basin. We’re living way below the compact allocation. I don’t think anyone should be rewarded for overdeveloping when others are not. It sounds like a simple and compelling message, but it’s misleading.”
As for cutting beyond the structural deficit, Mitchell said, “How do we move beyond that? What is the mechanism to do that? What does it look like? What we do know is that if more than 1.5 is needed, chances are we in the Upper Basin are already taking a hit. Senior water rights already being cut. … If the water is not there it can’t be delivered.”
Don’t just cut us, Lower Basin says
In response, J.B. Hamby, Colorado River commissioner for California, recently told the Desert Sun of Palm Springs that a successful plan can’t put all the pain on one basin or another, or one user or another.
“The only successful path forward is for everyone to compromise.”
For 19 million Southern Californians, millions of acres of prime irrigated farmland, Lower Basin tribes, Las Vegas and Central Arizona to exclusively bear the weight of drought and climate change is “not only not equitable, that’s iniquity,” Hamby told the Arizona Daily Star.
Said Kightlinger, “What I’m seeing right now is that the Upper Basin is not trying to reach a deal. They’re looking for arguments to bolster their position.
“They’re trying to make this about the Lower Basin. so they don’t have to do anything,” said Kightlinger, former general manager of Metropolitan Water District of Southern California.
The other Lower Basin representatives to the negotiations — the Arizona Department of Water Resources and the Southern Nevada Water Authority — won’t comment.
The Interior Department, Reclamation’s parent agency, offered only a very general statement about the negotiations.
“The Biden-Harris administration remains committed to ensuring the long-term sustainability of the Colorado River Basin for decades to come based on the best-available science and with robust input from stakeholders across the West,” the statement said.
"We continue to work with Basin states, tribes, and other stakeholders to support the exploration and development of a broad range of alternatives and foster collaborative, consensus-based approaches to alternative development.”
When do compact violations exist?
The 1922 compact requires the Upper Basin states to deliver at least 75 million acre-feet of water to the Lower Basin over a decade. All parties to the dispute agree to that.
No agreement exists as to whether the Upper Basin must deliver another 750,000 acre feet over 10 years to help satisfy the feds’ obligation to deliver water to Mexico. That’s how the Lower Basin states have long interpreted the compact, Fleck and Kuhn wrote.
The Upper Basin says their obligation stops at 75 million acre-feet over a decade, Fleck and Kuhn wrote. That issue and the question of how to deal with Colorado River tributaries in Arizona “have been disputed for decades,” Kuhn wrote in a separate post Feb. 22.
“(These issues) are, of course, totally inter-related, and when one peels back the layers of each, the problems get so complicated that the only real solution may be for the basin’s states and other stakeholders to ignore their past positions and grievances and negotiate a river management approach that works on the river we have today,” even if that means changing the compact, Kuhn wrote.
In this aerial photo, a bathtub ring of light minerals shows the high water mark on the shore of Lake Mead along the border of Nevada and Arizona in March 2023.
There’s also no consensus over whether the Upper Basin is actually close to failing to meet a legal obligation. Upper Basin officials and some scholars argue that a key reason for the decline in flows from lakes Powell to Mead is climate change — not because Upper Basin states are depleting them. Other scholars disagree.
“Neither one of us are lawyers, and when I think of that position as a non-lawyer, put yourself in the shoes of the Supreme Court,” Kuhn told the Star. “If you do, you’re gonna recognize if they have to reinterpret the compact because of climate change, it’s going to be every water compact in the West (that could come under legal scrutiny). That would be a huge precedent.
“One side or the other will be looking at it and say, ‘I’m not getting what I thought I would get due to climate change,’” Kuhn said, adding he assumes cooler heads will prevail before litigation occurs.
A distant threat draws closer
Until now, the issue of possible compact violations seemed distant.
For many years, the river delivered nearly 8.25 million acre-feet on average, annually, to the Lower Basin. From 2015 through 2019, 9 million acre-feet a year rolled down the river to Mead, spurring charges from Upper Basin officials that the Lower Basin was “draining” Lake Powell.
For comparison, 9 million acre-feet is what the Central Arizona Project canal system at its peak sent from the river to Phoenix and Tucson over six years.
The 10-year flow to the Lower Basin from 2014 through 2023 was 86.4 million acre-feet, far above what the compact requires, Fleck and Kuhn pointed out.
But releases have generally withered of late, save for a very wet 2023. For the next three years, Reclamation expects to release only 7.48 million acre-feet a year to Mead. If that trend holds, the Lower Basin will be getting 83 million over the 10 years ending in 2026 -- only 500,000 acre-feet above the minimal delivery as the Lower Basin states see it.
Until new federal guidelines are adopted, it’s not known what the annual release will be in 2027, but if it’s even below about 8.5 million acre-feet, the 10-year flow through that year “could drop below the tripwire,” triggering compact issues, their blog said.
That trend could worsen if heavy releases of 2018 and 2019 are replaced in the 10-year picture by much lower releases in 2028 and 2029, Fleck and Kuhn said.
“If the river’s hydrology stays dry, it’s very safe to say it will happen,” said Kuhn of releases dropping below their possible legal minimum.
The possibility of compact issues arising in the near term “could and should influence how we share this river” through the seven-state negotiations, Fleck added.
“In the past we got away with avoiding this problem. There was a bunch of extra water,” he said.
“The reality is that we are either going to negotiate in the next 3 years a water sharing solution among the 7 states, or, if we cross the tripwire, we end up with disastrous litigation.”
No agreement on how much water is used
A possible way out of the current morass would be for the Upper Basin to agree to some additional cuts in their water use, the two researchers said. In return, Lower Basin states would agree to cut their use further than they’ve already agreed to do, and to not litigate over the compact.
“It’s a compromise where both sides have to give in some on their entrenched legal positions,” Fleck said.
If the Upper Basin “wasn’t constantly being threatened with a compact call, maybe they would be more willing to participate” in taking cuts, said Elizabeth Koebele, an associate political science professor and water researcher at the University of Nevada-Reno.
But today, the states can’t even agree on how much water the Lower Basin states use — or overuse.
Colorado commissioner Mitchell’s office has been regularly circulating a slide showing the Lower Basin used at least 10.39 million acre-feet annually from 2020 through 2022. She compared that to Upper Basin use of no more than 4.5 million acre feet annually in those years.
She counts 1.1 million acre-feet of annual Lower Basin evaporation as strictly Lower Basin use. Some Lower Basin researchers say all states should account for evaporation in their use because they all share benefits of the river and its reservoirs.
A bigger flash point is that Mitchell’s numbers include 2.2 million acre-feet a year in Lower Basin — mainly Arizona — use of Colorado River tributaries. Those include the Gila, Salt and Verde Rivers in central and eastern Arizona. Both cities and farms in those areas draw upon them for much of their supplies.
The Colorado Water Conservation Board pulled that figure from a Bureau of Reclamation report about river water uses and losses for 2001 through 2005 — the most recent report the agency said was available.
“Provisional data” that Colorado received verbally from the bureau shows similar Lower Basin tributary use from 2006 through 2015, the slide says.
The Star asked the bureau on Monday if this statement can be verified. On Friday, Becki Bryant, a bureau spokeswoman, responded, “We haven’t had a chance to review the document and compare numbers.”
Imperial’s Hamby’s response to Mitchell is that the U.S. Supreme Court ruled in its landmark, 1963 Arizona v. California decision over river water supplies that Arizona didn’t need to count the tributary water use toward its allocation.
Colorado’s Kuhn, however, said that decision looked strictly at the meaning of the 1928 Boulder Canyon Project Act that authorized Hoover Dam’s construction — not the 1922 compact.
The Upper Basin states are using tributary use figures to try to bring water use of the Salt River Project — a Phoenix utility that serves Salt and Verde river water to cities and farms — into the negotiations and try to force cutbacks there, Kuhn said.
“When you start bringing SRP into the negotiations, it becomes an enormously complicated issue,” Kuhn said. “If SRP’s use is at risk, it’s the kind of thing that would set politics in Arizona upside down.”
In Colorado, Mitchell uses the slide “with a great deal of success, as a communications strategy,” Kuhn said. “The bottom line is that the messaging is effective.”
But newer data from the Bureau of Reclamation shows that generally, the SRP water use has been “trending” downwards over the past few decades, said Kathryn Sorensen, research director for Arizona State University’s Kyl Center for Water Policy.
“The numbers (from Colorado officials) don’t make sense to me. They are based on extrapolations of data that is twenty years old,” Sorensen said.
“Playing games with the numbers”
Kightlinger accuses Colorado’s Mitchell of “playing games with the numbers.”
For one, he noted that in the last couple of years, the Lower Basin’s diversions from the river — not counting tributaries — were closer to 6 million acre-feet a year, and it dropped slightly below that in an unusually wet 2023.
As for her use of tributaries, “She’s not following the law or protocol. She’s just coming up with a way to boost this number up. It’s a lot of rhetoric. It’s not honest.”
Mitchell’s office didn’t respond to these comments.
Could a compact call happen?
The Upper Basin states said in their statement that.
"We remain optimistic that the 7 Basin States will be able to reach a consensus on a 7 State alternative."
Kightlinger isn't so sure of that A year ago, Kightlinger would have said that an Upper-Lower Basin struggle over the compact that could head to court was highly unlikely, he said. Now, “I think there’s a reasonable chance it could happen,” he said.
“Based on the rhetoric I hear from the Upper Basin, I see them drawing a fairly firm line,” he said.
The Green River, a tributary of the Colorado River, flows in January 2024 in Green River, Utah.
But, “a lot of times people posture till the brink, then in the heart of hearts they know they need to make a deal,” he said. “They’ve always managed to resolve things over the last couple of decades.”
For now, there’s not even a formal process for the Lower Basin to initiate a compact call or to participate in a decision carrying one out, said Fleck, Kuhn and Sarah Porter, director of ASU’s Kyl center.
Under a 1948 compact signed by the Upper Basin states, the Lower Basin states could ask for a water use cut from the Upper Colorado River Commission, which has four members representing Upper Basin states and one representing the feds. But Kuhn said he doesn’t see the commission agreeing to one unless members thought it would lose in court.
Otherwise, “a call is basically unenforceable,” Porter said.
Longtime Arizona Daily Star reporter Tony Davis explains what "dead pool" means as water levels shrink along the Colorado River.
