Lake Mead is barreling faster than ever toward ‘system crash,’ top experts say

The Colorado River Basin faces a complete “system crash,” with little chance that a wet winter will fully prevent a worst-case scenario, a leading group of experts says in a new academic paper.

That is, unless water managers can get serious about cutting water use fast.

Study author Anne Castle, a fellow at the University of Colorado, Boulder, served as the assistant secretary for water and science at the Interior Department from 2009 to 2014. In an interview, she said the nation’s two biggest reservoirs, Lake Powell and Lake Mead, are rendered useless in providing accessible water storage below certain elevations.

“If the reservoirs drop to that level, we’re not getting any benefit from them anymore,” Castle said. “If that happens, it’s like the Colorado River is running free. We get what we get, what nature provides, and we have no ability to buffer dry years.”

At Lake Mead, Southern Nevada’s primary water source, that crucial number is 975 feet above sea level. On Friday, the reservoir sat at about 1,049 feet, though the Trump administration’s recent decision to reduce flows out of Lake Powell could see Lake Mead drop some 28 feet by July 2027, far past any previous record low.

The story at Lake Powell is far more complicated. Below 3,500 feet in elevation, long-ignored plumbing problems at Glen Canyon Dam could mean that federal water managers cannot send any water downstream at all.

Thus came the emergency decision to prop up Lake Powell with reduced outflows and water moved in from an upstream reservoir in order to avoid near-term catastrophe.

Rhett Larson, a water law professor at Arizona State University, said in an interview that the paper highlights the lack of options water managers will be left with to even out the system if snowpack shortages persist.

“They’ve already shot that bullet, and you can’t unshoot it,” Larson said. “Unless Mother Nature bails us out, I don’t see what emergency measures the federal government can take next year.”

Southern Nevada’s water savings account

A more favorable snow season could buy the nation’s two biggest reservoirs and their hydropower dams about two years before crisis conditions return, according to the study, which was released June 1. With a supercharged El Niño season on the way, that’s possible.

The researchers say a system crash would not have immediate effects for residents of larger cities in the Southwest.

“A system crash doesn’t necessarily mean that people’s taps go dry because there are other sources to rely on,” Castle said. “But not every water user has that potential of using other sources. That’s why we’ve expressed concern that agricultural water users, and maybe some rural communities that don’t have other supplies available, could be in a world of hurt.”

That’s true, too, for residents of the Las Vegas Valley.

Water managers have claim to 10 years of water available for use in the Las Vegas Valley stored in different areas, Southern Nevada Water Authority spokesman Bronson Mack said. That’s about 2.2 million acre-feet of water; last year, the region’s water use came in at 198,000 acre-feet after accounting for credits from water recycling.

An acre-foot of water, by most estimates, is enough to sustain two single-family households for one year.

Groundwater aquifers in the Las Vegas Valley, Arizona and California account for some of that banked water, Mack said. Out of state, it functions as a water transfer, where other jurisdictions would use the groundwater while Southern Nevada takes more from Lake Mead.

The low-level, third intake at Lake Mead — a massive infrastructure project completed in 2013 — allows Southern Nevada to access the 900,000 acre-feet of water it has stored in the reservoir.

Southern Nevadans’ sacrifice in contributing to conservation in multiple ways, whether that’s ripping out grass in their front lawns, removing decorative grass or complying with a ban on evaporative cooling systems, have all been to accommodate to the river’s new reality, Mack said.

“What we have been doing has been with the foresight that conditions on the Colorado River could get worse, and that is exactly what we have been seeing over the past 25 years,” Mack said in an interview.

Cuts could not be enough

The desperately needed cuts in use are likely to come first from the Lower Colorado River Basin states of Nevada, California and Arizona. Nevada’s sister states produce the lion’s share of the country’s winter leafy greens and vegetables; agriculture accounts for more than half of all water used from the river, while cities only use about 18 percent.

On or before Oct. 1, the Trump administration is expected to impose new guidelines for how all seven states share the river because state officials tried and failed for multiple years to come up with an updated, 20-year operating regime.

While the Upper Basin states of Colorado, Utah, New Mexico and Wyoming stonewall any admission that they could take mandatory cuts in water use, the Lower Basin has stepped up with a plan to spare 1.25 million acre-feet in both 2027 and 2028.

Nevada alone could face an annual cut anywhere between a sixth and a third of its allocation under the plan, which would need to go before the Arizona Legislature and governing water agency boards in California and Nevada for approval.

Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University, said in an interview that the Lower Basin’s efforts are not enough to solve the crisis.

It’s difficult to absolve the Upper Basin of the responsibility of shouldering some of the pain of cuts to water use, she said.

But while she agrees that it is complicated to ensure that a cut upstream doesn’t impact a downstream user with more senior water rights, Porter said the makeup of the reservoir system plays a role, too. Upper Basin users, without major reservoir storage and not dependent on dam infrastructure, can continue to use their water as it flows down through the headwaters.

“Negotiators in the Upper Basin don’t have a strong incentive to push deep, deep cuts on their water users right now, unlike the Lower Basin, for whom it’s existential,” Porter said.

Have state officials ‘failed’?

The study’s authors make their dissatisfied position on how state officials approached the interstate dealmaking process clear. Castle said the existing system did not allow for much room for progress.

“It becomes very difficult to compromise for the benefit of the whole system,” Castle said. “You can stand on your legal rights and fight to the death for the interests of your particular water users, all while the system crashes around you. And those water users get hurt, too.”

Both Porter and Larson, the water law professor, said in the wake of how bad conditions are, all signs point to the U.S. Supreme Court. Until now, officials have presented that as a last-ditch effort that could cost taxpayers millions and delay progress several years.

“I’ve started correcting people when they say the negotiators failed, because I think the word ‘fail’ presupposes that there was a possibility of success,” Porter said. “ I don’t think this context of a consensus-based agreement really ever had a chance.”

However, Larson said it’s not clear what laws or interpretations of those laws will apply. All modern laws governing the Colorado River system assume the functionality of dams and reservoirs, he said.

“It’s either going to catalyze a radically new imaginative deal, which is what I hope it would do, or it is going to catalyze a rapid run to the courthouse,” Larson said.

Larson, unlike Porter, said he believes it’s prudent to say state negotiators have failed to deliver on their promises of a seven-state deal. He said he likens the Colorado River dilemma to a family affair.

“Mother Nature is sick in bed; she will not bail us out, and she’s not a part of the solution. We shouldn’t count on her,” Larson said. “Dad, the federal government is drunk in the garage. He has failed. He hasn’t led us to a solution.”

And the family’s children, or state officials, have failed to pull themselves together, too, Larson said. That leaves local governments and the private sector to step up with solutions.

While the authors’ definition of a system crash won’t immediately affect urban residents, Larson said it’s imperative for everyday people to hold their leaders to account on the issue of water, especially as voters head to the ballot box.

“It’s highly unlikely that any time in the next few years you’re going to see this actually hit your taps in your home, so you shouldn’t panic,” Larsons said. “Panic is a liability. Panic doesn’t do us any good, but concern is an asset that should be cultivated.”