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Colorado River study means it's time to cut water use now, outside experts say

A ring of light minerals delineates the high water mark on Lake Mead, the source of much of Tucson’s drinking water. Arizona has committed to leaving up to 720,000 acre-feet of its CAP supply in Lake Mead if it falls low enough.

Less water for the Central Arizona Project — but not zero water.

Even more competition between farms and cities for dwindling Colorado River supplies than there is now.

More urgency to cut water use rather than wait for seven river basin states to approve new guidelines in 2025 for operating the river’s reservoirs.

That’s where Arizona and the Southwest are heading with water, say experts and environmental advocates following publication of a dire new academic study on the Colorado River’s future.

The study warned that the river’s Upper and Lower basin states must sustain severe cuts in river water use to keep its reservoir system from collapsing due to lack of water.

That’s due to continued warming weather and other symptoms of human-caused climate change, the study said.

The study from Utah State University said Arizona and the other two Lower River Basin states may have to slash their take from the river up to 40% by 2050 to keep reservoirs from falling too low. The other Lower Basin states are California and Nevada.

The study also says the four Upper Basin states must dramatically scale back or kill plans to divert more water from an already depleted river. Those states are Colorado, New Mexico, Utah and Wyoming.

The study appeared as the seven states are preparing to renegotiate the operating guidelines that expire at the end of 2025.

More immediately, the first cutbacks in Central Arizona Project deliveries from the river — primarily to Central Arizona farmers — appear likely for next year.

Here’s the outlook of some experts:

CAP cuts: Officials of Arizona’s two biggest water agencies, the Arizona Department of Water Resources and the Central Arizona Project, declined to comment specifically on the study. They responded with more general, emailed statements acknowledging the need to adapt to continued drying and stating their readiness for the upcoming negotiations.

Outside water experts pulled no punches, however, on what they think this study means for Arizona.

Water policy analyst Kathryn Sorensen said she agrees with “everything” in the study, adding that it means “without bonus snowpack on a near-constant basis, some will have to use less water or go without.

“We are going to have to take a much harder look at how water is used in the basin,” said Sorensen, research director of Arizona State University’s Kyl Center for Water Policy and a former Phoenix water utility director.

Arizona leaders must start a serious conversation of how to deal with less water, and stop thinking about how to make other places take cuts, said John Fleck, author or co-author of two books on the river and head of New Mexico’s Water Resources Research Program.

“We have to be honest about this now and have serious conversations rather than sort of clinging to the past. Now, we need to be looking seriously at how much water is used in various sectors of the economy and looking at how the reductions can be absorbed,” Fleck said.

Arizona ducked these questions in negotiating the three-state river drought contingency plan that was approved in 2019, he said, even though it did commit to leaving up to 720,000 acre-feet of its CAP supply in Lake Mead if the lake fell low enough.

Except for Pinal County farmers, who stand to eventually lose their CAP water, other sectors of the state’s economy won’t be significantly affected by those cuts.

That’s largely because the Gila River Indian Community and other tribes agreed to leave large amounts of water in Lake Mead to prop it up — a practice that may or may not continue after 2025.

CAP future: Fleck and most other water experts don’t expect that all of the CAP’s supply will disappear, no matter what.

The 1968 federal law authorizing the project makes that legally possible, saying California won’t lose a drop of its river water until CAP loses everything.

“No matter what they agreed to in 1968, you can’t completely dry up the CAP canal,” said Brad Udall, a co-author of the new Utah State study and a veteran water researcher in Colorado. “That would be politically infeasible, economically stupid and incredibly harmful to Arizona.”

It seems inconceivable that any one place will be driven to a crisis-level water supply, while everyone else goes along using water unperturbed, said Jennifer Pitt, a National Audubon Society activist.

“What president, what Congress would allow that to happen?” asked Pitt, Audubon’s Colorado River program director.

The 2019 drought plan calls on California to take up to 350,000 acre-feet in cuts once Lake Mead drops low enough, despite the 1968 law.

That plan offers a model for how the next round of negotiations are likely to proceed, with Arizona and Nevada taking bigger cuts early and California taking cuts later, said Bill Hasencamp, Colorado River Resources Director for Southern California’s six-county Metropolitan Water District.

“There’s two balances at play here. One recognizes a priority system ... but there’s also a reliance on the fact that there is a shared risk on the river,” Hasencamp said.

Overall, Hasencamp called the study’s findings “pretty grim.”

While there’s a general consensus that the future will be drier, “the real question is what is a good future to plan for?” Hasencamp said, adding, “How long and how dry is still going to be a big question.”

Farms vs. cities: Longstanding tension between the two sides over water will only worsen if the new study’s forecasts pan out, the experts said.

Already in Arizona, farmers and their allies along the river are fighting plans by the rapidly growing town of Queen Creek to buy 2,000 acre-feet of Colorado River rights held by farmland in the town of Cibola in La Paz County.

The Arizona Department of Water Resources has endorsed this water rights transfer, which ultimately must be approved by the U.S. Bureau of Reclamation, over objections from riverfront residents that this purchase will set a precedent for larger-scale purchases along the river for the Phoenix and Tucson areas.

In Colorado, rural communities are organizing to fight such transfers that they fear would “buy and dry” their areas.

Eric Kuhn, one of the new study’s co-authors, speculated that over time, the Central Arizona Project will make a bunch of deals with irrigators along the river to buy water rights, following the footsteps of Colorado and Southern California water transfers.

“CAP water flows uphill to the money. Municipalities in Central Arizona have political power and money. How many votes are there along the river vs. how many votes there are in Maricopa County?” said Kuhn, retired director of the Colorado River Water District in Glenwood Springs.

It’s pretty clear the Imperial Irrigation District, the river basin’s largest water user by far, will also be a target for future water transactions to help cities, Udall said. Imperial takes more than one-third of the Lower Basin’s 7.5 million acre-feet annual supply from the river.

“California would have to contribute to keep some water in that canal. That’s the only place that water would come from. Because Imperial is so big, people will be looking to Imperial to contribute to this,” said Udall.

He added, “As you can completely imagine, this is all verboten to talk about,” because the subject is so politically sensitive. Farmers in Imperial, who have felt for years that cities have a “target on our backs,” will go crazy when this subject comes up, he said.

A spokesman for the Imperial district in El Centro, west of Yuma, responded by saying it won’t agree to new cutbacks. The district is already conserving and transferring about 500,000 acre-feet a year to other users, totaling more than 7 million acre-feet a year since the late 1990s, said district spokesman Robert Schettler.

Upcoming negotiations: Arizona’s top water officials and some outside water experts and activists are taking different stances toward the impending seven-state river negotiations.

Those talks should start sometime this year, although the Bureau of Reclamation, which runs the reservoirs, isn’t being specific on when.

It’s working on developing a plan “that ensures that all of our partners on the river are able to participate and contribute in a collaborative and meaningful way,” bureau spokeswoman Patricia Aaron said.

Reacting to the negotiations and the new study, a CAP official said that agency has long understood risks to the Colorado River system associated with a hotter, drier future, and realizes that more work is needed to address them for the longer term.

“To that end, we are continuing our work with the Arizona Department of Water Resources, Bureau of Reclamation, CAP customers and stakeholders, including tribal partners to prepare for the development of post-2026 Colorado River operating rules,” said Chuck Cullom, CAP’s Colorado River program manager.

He added that CAP is preparing to carry out the next phase of cuts under the drought contingency plan affecting farmers and some Phoenix-area cities, “in the increasing likelihood” of shortages next year.

The state has a good start in preparing for the seven-state talks, thanks to the structure of water interest groups the state assembled to put together the 2019 drought plan, said ADWR Director Tom Buschatzke.

“We anticipate looking at a variety of hydrologic futures, how they might impact lake levels, how we might protect those lake levels under those hydrologic scenarios, as well as how our efforts might equate to the frequency or magnitude of reductions,” Buschatzke said.

When, how to cut water use? Others say Arizona shouldn’t wait five years for a fix.

“Caution is the better part of valor in this case. There really is no agreement about what happens if reservoir levels fall below 1,025” feet, ASU’s Sorensen said, speaking of the elevation at Lake Mead where major cuts in deliveries to Arizona cities and tribes could begin.

“At a minimum, there needs to be discussions and clarification about what actions to be taken if that’s the case. If water levels continue to fall, we could find ourselves in a place where we are looking at very, very serious scenarios with real consequences,” she said. “We could be in a place where we’re living in those shortages for much longer periods of time than we anticipated.”

There is a whole host of conservation measures that local and state officials could work on now besides agricultural water use, said Sandy Bahr, director of the Sierra Club’s Grand Canyon chapter.

Why, for instance, isn’t every home plumbed for gray water use? Why not, she asked, design and build “net zero” homes that use no more water than they generate in wastewater that is reused? That’s an idea the Sierra Club tried unsuccessfully to promote a few years back in the Arizona Legislature.

Retiring coal-fired power plants faster than now planned can save water because they use a lot, Bahr said.

Having water priced more “appropriately” — charging more for water use beyond what homeowners need for drinking, cooking and bathing, is also advisable, she said — something Tucson already does in its water rate structure.

Val Little, who chairs a state water advisory panel in Tucson, said she can’t suggest conservation solutions because “we don’t know how much water we are going to get and how solid those numbers are going to be.”

Contact reporter Tony Davis at or 520-349-0350. On Twitter@tonydavis987

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