Andy Mueller, the general manager of the Colorado River District, delivered a strong message at the organization’s annual seminar in September. It was time, he declared, for Colorado to plan for potential curtailment of Colorado River diversions as necessary to comply with the compact governing the river among the seven basin states.
Compact curtailment, sometimes described as a compact call, means that those with water rights junior to or filed since the Colorado River Compact of 1922 would be vulnerable to having no water. That could potentially include most of Colorado’s Front Range cities, which get roughly half of their water from the Colorado River and its tributaries. It could also include some towns and cities on the Western Slope and even some farmers and ranchers on the Western Slope as well as some agricultural users reliant upon transmountain diversions.
The precise trigger for such a call, reduced flows to lower-basin states, is open to argument. An ambiguous clause in the compact could be hotly debated, and likely will be, if river flows continue to decline. Mueller spoke of legal saber rattling by lower basin states.
This is not entirely a new subject. Colorado has been talking about the potential for compact curtailment for about 20 years but has not pursued it. The state government disputes the immediate need. What almost everyone can agree upon, however, is that it will be foolish to assume that the near-average or better river flows of the last two years will prevail.
Reservoir levels in the basin have been sagging for most of the 21st century. Most dramatic was the runoff in 2002 when the river yielded only 3.8 million acre-feet. Delegates of the seven basin states who had gathered near Santa Fe in 1922 to apportion the river assumed average flows of at least five times that much.
Flows in 2003 and 2004 were only marginally better. Slowly, there was acceptance of extended drought unknown in the 20th century. In 2017, a study by Brad Udall and Jonathon Overpeck identified warming temperatures as just as important as drought in explaining the declines. They called it ‘aridification’.
By May 2022, the situation looked grim at Powell, the reservoir that the upper basin uses to fulfill its commitment to lower basin states as specified by the compact to the lower-basin states. Water levels had receded so much that tracks laid into the canyon wall to construct Glen Canyon Dam emerged. They had been underwater since the reservoir began filling in the mid-1960s.
It might have worsened. Modeling evaluated the risk of Powell having too little water to generate electricity by the next year. Some talked about potential for the reservoir to have too little water to pass any downstream, what is called dead storage.
Instead of further decline, snow fell in prodigious quantities during the next winter of 2022-2023 across parts of Colorado, which is responsible for 55% of total flows in the river, as well as in Wyoming and other upstream locations. Stock fences were entirely buried in some places of the Yampa Valley.
The runoff that resulted was the third-best in the Colorado River in the 21st century. Five more consecutive runoffs of the same magnitude would fill Powell and all the other reservoirs in the Colorado River Basin, according to Utah State University’s Jack Schmidt.
What if, instead of epochal snows in the Rockies, pitiful runoffs parallel to those of 2002 to 2004 return?
“Let’s hope for the best and plan for the worst,” Mueller said at the seminar in Grand Junction held by the River District. The Glenwood Springs-based district — its official title is the Colorado River Water Conservation District — was created in 1938 to represent the interests of 15 of the 20 counties on the Colorado River drainage.
Several people who heard Mueller’s remarks applauded them. Colorado, they say, should not wait until the very last minute before devising a strategy. Curtailing water use will be a very difficult and lengthy process. Better to get on it now.
But there is also another level to the discussion, one of moral and ethical questions, according to one long-time Colorado Rive observer
“How do we, as a community of two nations, seven states and Mexico, and 30 sovereigns (Native American tribes) — how do we come together to recognize that this is a shared resource, and climate change is changing the resource. We need to understand how to collaboratively share the resource in a way that will be necessary to live in a climate-altered world,” says John Fleck, an Albuquerque-based author of several books, including “Water is for Fighting Over: And Other Myths about Water in the West.”
Colorado and other upper basin states, he observes, are saying it’s not their problem because they have met their commitments.
”That is morally wrong to me,” he said in an interview. As a practical matter, it’s also “seems really dumb” because in the political and legal system the upper basin states are unlikely to win that argument in a drier 21st century. “That just ain’t gonna work.”
The 1922 compact apportioned 7.5 million acre-feet for the upper basin states – Colorado as well as New Mexico, Utah and Wyoming — and 7.5 million acre-feet for the three lower basin states of Arizona, California and Nevada. The compact assumed deliveries to Mexico would be required by a future compact, and they also realized significant evaporation. Altogether, they assumed more than 20 million acre-feet flows in the river. That has rarely happened.
The debated clause is called the “non-depletion obligation.” It says the upper basin states must allow river flows of 75 million acre-feet over a rolling 10-year average at Lee Ferry. Lee Ferry is in Arizona, just below Glen Canyon and a few miles above the Grand Canyon.
Colorado’s position is two-fold. It argues that the lower basin overuse remains the primary problem coupled with climate change. And Colorado and its siblings in the upper basin didn’t create either.
“We take the position that we are not the cause of trending lower flows over the past 20 years,” said Jason Ullman, the state water engineer in a statement from the Colorado Department of Water Resources in response to a query by Big Pivots. “Climate change and aridification impact snowpack and soil moisture, which in turn reduce flows into the Colorado.”
Colorado and other upper-basin states altogether use between 3.5 and 4.5 million acre-feet annually compared to roughly 10 million acre-feet by the lower-basin states.
“This is why Colorado believes that the responsibility to bring the river back into balance primarily lies with the lower basin and the need to bring uses within their compact apportionment with a plan to use less during times of shortage,” Ullman said.
Mueller, in his remarks at Grand Junction, didn’t disagree with that stance. But he insisted that Colorado needs to prepare a backup plan if the state must releases more water downstream, forcing the curtailment of its diversions.
“I think the best thing our state can do is, while continuing to make a very good case that we’re not the cause of this and that climate change is causing it, we need to be prepared in the event it occurs,” said Mueller
River District directors had recently asked Ullmann to “please get moving with compact curtailment rules,” he said.
The state needs to come up with the “right funds, have the right personnel, and get moving with our compact curtailment rules,” said Mueller.
This, he added, should not be seen as a sign of weakness by Colorado in the interstate negotiations, but rather as a sign “that we’re smart, that we’re helping our water users and our communities plan for the future.”
Colorado and other basin states are in the midst of negotiating new guidelines that govern operation of the two big reservoirs, Mead and Powell. The first set of guidelines were adopted by the states and the Bureau of Reclamation in 2007.
The regulations were abetted by the drought contingency plan, which brought cuts in water use to the lower basin and new water management tools to the upper basin.
The 2007 guidelines expire at the end of 2026. The states must come up with a new agreement that recognizes the shifted realities by the end of 2025.
State government does not absolutely reject the need for compact compliance rules, but the statement attributed to Ullman cites these negotiations.
“It would be imprudent to undertake any rule-making for compact compliance without knowing the terms of any seven-state consensus regarding operating guidelines that includes releases from Powell. Therefore, it is the position of the state engineer that undertaking compact compliance rule-making now would be premature.”
That sounds like “no”. But there’s more.
The state engineer has the exclusive authority to make and enforce regulations that enable Colorado to meet its compact commitments.
“Colorado recognizes that the first critical step in being able to administer to the compact, if necessary, is the ability to accurately measure diversions,” said Ullman in the written statement. “The state engineer is pursuing measurement rules for diversions to establish accuracy standards and better define where measurement is necessary. The goals of this effort include increasing the consistency of water right measurement so that Colorado sends only what is required to maintain compact compliance and not more.”
How much Colorado might have to curtail would depend upon findings of the Upper Colorado River Commission, which is governed by a 1948 compact. The state engineer has adopted rules for one of the four water divisions on the Western Slope, and work is progressing in a second district. The engineer plans to also adopt measurement rules in the other two districts.
What do the big Front Range diverters with post-compact water rights have to say?
Denver Water falls in line behind the state position. It has major diversions from the Colorado River tributaries in Grand and Summit counties.
“We recognize interest from some in rules for compact administration, but it’s very important that this effort be undertaken at the right time, with thoughtful collaboration among water interests statewide. We know that the State Engineer laid out a potential process a few years ago, with the first step being a focus on measurement rules. If and when it becomes necessary to take further action, we trust the State Engineer to so do. In the meantime, we think it’s critical that states, including Colorado, should keep their focus on the post-2026 guidelines being negotiated now, and not be distracted during a process of the greatest importance to Colorado’s future.”
Northern Water, operator of the Colorado Big-Thompson diversions from the Colorado River headwaters in Grand County, says it will defer to the state. “Northern Water looks to the State of Colorado as the leader on matters related to interstate water agreements,” said public information officer Jeff Stahla.
Colorado and other upper-basin states handily met their compact delivery obligation during the last decade — no matter how that clause in the Colorado River Compact is interpreted. With warming of 1 to 4 degrees baked into the climate in coming decades, rivers flows might well continue to decline, setting up a legal question about delivery obligations that would likely end up before the Supreme Court…
Allen Best publishes the e-journal Big Pivots, which chronicles the energy transition in Colorado and beyond.