‘A whole new reality’: Bolder measures needed to prevent extreme water shortages in cities like Phoenix and Las Vegas that depend on the Colorado River

A recent study found that even if cities in the region such as Denver, Phoenix and Las Vegas drastically cut back on water use, the 40 million people who live in areas served by the Colorado River would face catastrophic water shortages.

Water shortages could begin as early as this summer, experts told Live Science, as Lake Powell’s snowpack reaches record lows and spring runoff to the Colorado River is expected to be minimal. And while major cities in the region have already reduced per capita water consumption by up to 58% between 2002 and 2025, they cannot solve the problem alone.

“We can’t just impose everything on the residents of these cities and tell them to use less water, because it’s still not enough. [to prevent water shortages]Renee Oblinger, assistant professor in the Department of Energy and Mineral Engineering at Penn State University and lead author of the new study, told Live Science. “No matter what mitigation measures we take, we will have to adapt to a warmer world with more severe and more frequent droughts.”

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The findings make clear that bolder measures are needed to prevent disasters in the Colorado River Basin. But what exactly are those steps?

1 piece of the puzzle

Seven states draw water from the Colorado River: Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming, and the amount of water allocated to each region is controlled by a century-old document called the Colorado River Compact.

But the Colorado River Basin, like the rest of the southwestern United States, has been experiencing a 25-year drought. Between 2000 and 2019, the river’s flow decreased by 20% due to climate change and overuse of water to supply cities, agriculture, and industry.

Since finding new sources of water is unlikely, Oblinger and his colleagues analyzed what would happen if the three major cities that benefit from the river, Denver, Las Vegas, and Phoenix, reduced their water consumption by about 25% under a variety of climate scenarios ranging from global temperatures of about 2.9 degrees Fahrenheit (1.6 degrees Celsius) to 4.3 degrees Celsius (4.3 degrees Celsius) above pre-industrial levels.

Their results were published in Water Resources Research in December 2025. In most climate scenarios, demand management, including a wide range of strategies such as raising awareness, offering rebates, and subsidizing low-flow devices, has not been able to compensate for the decline in urban reservoir storage caused by rising temperatures and decreasing precipitation in the region. Although Denver isn’t technically located in the Colorado River Basin, it gets half of its water from the river, but it was the only exception. Demand management compensated for the reduction in river flow in the city’s two high-emission climate scenarios. But Oblinger believes some of these optimistic results may be due to the way the model handles uncertainty.

Cities affected by the Colorado River Basin have reduced water use through programs aimed at both demand and reuse. In Las Vegas, for example, residents receive cash rebates when they replace water-rich lawns with desert plants. The city, which gets 90% of its water from the Colorado River, returns 40% of the water it uses to Lake Mead after treatment, where it can be reused.

Brad Udall, senior water and climate research scientist at Colorado State University’s Colorado Water Center who was not involved in the study, said cities have taken significant steps to reduce their footprint, and improvements will continue. As a result, some of the region’s largest cities use less water per person than they did decades ago.

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But the more efficient cities become, the fewer opportunities they have to conserve and reuse water, Udall told Live Science.

more water users

The findings highlight a reality that scientists have known for years. Demand management alone won’t compensate for the Colorado River’s declining flows, said Sharon Megdal, a University of Arizona professor and director of the Water Resources Research Center who was not involved in the study.

While cities account for only 18% of the region’s water use, more than 70% of the basin’s water is consumed by agriculture. “Agriculture is the biggest user,” Megdal told Live Science.

“We’re not going to solve this problem unless we tackle agriculture in a big way,” Udall agreed. “Agriculture is 70 percent of the problem, so it has to be at least 70 percent the solution.”

Although individual farmers have preferential water rights to Colorado River water, meaning they receive their full allocation regardless of whether they are in short supply, Udall said there is growing political pressure to allocate more water to cities and reduce farmers’ consumption. For example, water managers may decide that Arizona farmers must give up water to feed the Central Arizona Project canal, which carries water from the Colorado River to the south-central part of the state, including Phoenix and Tucson.

Since 2019, the Colorado River has shrunk significantly and is now 35% smaller than its 20th century average. “I’ve never seen anything like this,” Udall said. “If these flows continue to decline, I think downstream agriculture will not be able to get supplies.” 1777073561 Those supplies will then be redistributed to the city. ”

The problem is that downstream farmers grow crops that economically benefit the region through export, such as alfalfa, cotton, vegetables, and citrus. In Arizona, approximately 20% of agricultural land is used to grow alfalfa for cattle feed. The state is also the largest producer of cotton in the Colorado River Basin and grows up to 90% of the leafy vegetables consumed in the United States and Canada.

To reduce water consumption, farmers can change irrigation techniques and crop patterns, Megdal said. Drip irrigation, which delivers water directly to the roots, reduces evaporation and reduces water use by up to 50% compared to methods such as flood irrigation used for cotton and alfalfa. Thirsty crops such as alfalfa can be replaced with low-moisture feed mixtures consisting of wheat, barley, oats, rye and peas. Lately, Megdal said guayule, an alternative to rubber, has been attracting attention as an alternative crop for farmers.

However, farmers may respond to demand and enter into long-term contracts with buyers. “It has to be economical,” Megdal says.

While agriculture needs to switch to more efficient irrigation, Udall said it’s also important to recognize that seemingly wasteful methods, such as furrow irrigation and flood irrigation, can still replenish depleting aquifers.

Megdal added that some farmers are leaving their fields fallow, but this is likely to happen more and more as water shortages worsen.

Renegotiation of water rights

The Colorado River Compact is up for renewal this year, meaning there is an opportunity to devise a more sustainable agreement, Oblinger said. But negotiations have stalled among the Upper Basin, which includes Colorado, New Mexico, Utah and Wyoming. and the Lower Basin, which includes Arizona, Nevada, and California. Officials are debating the exact wording of the document, but the underlying problem is that the upstream region is already using less water than is allocated in the agreement, while the downstream region needs more water than it gets.

Upstream officials argue that future cuts should only be imposed on downstream regions. But that won’t happen, Udall said, because changing the situation would require digging deep trenches throughout the Colorado River Basin. No matter what upstream communities think they are entitled to, they must accept reduced water use, he said.

reality check

The future of the Colorado River is bleaker than ever, and solutions must be found and implemented immediately.

With little snow in the winter, and what little snow that did fall melted in early March instead of April, river flows could reach record lows this spring and summer. “This is unprecedented. It’s human-made. It’s horrible, it’s horrible, it’s terrible,” Udall said.

Udall estimates that Lake Mead, which is home to about 25 million people in cities such as Las Vegas and Los Angeles, and Lake Powell, which supplies Lake Mead and Native American tribes, will only be about 20% full in the coming months. If the reservoir’s release rate is not adjusted, water levels could drop and Glen Canyon Dam would no longer be able to produce energy. The dam typically produces enough electricity to power more than 350,000 homes.

“We’re getting closer to Deadpool,” Udall said. The water level in the reservoir has fallen so low that it cannot flow downstream. “That has never happened and it is very serious.”

Megdal said it will take years to recover from the current conditions of unusually high rainfall and runoff. “It’s a difficult situation,” she said. “We really have to adapt to a new normal.”

To make matters worse, “data centers are popping up all over the region,” Oblinger said. Medium-sized data centers use up to 300,000 gallons (1.4 million liters) of water per day for cooling, and this amount will only increase as temperatures rise. Much of the water flowing through the system can be reused, but some is consumed to power the data center.

Some small steps are already underway to alleviate this problem. Megdal said some municipalities purchase water rights and groundwater from rural areas in the region. For example, the fast-growing town of Queens Creek, Arizona, buys groundwater from farmers and investors in the sparsely populated Halquahala Valley. Arizona is also developing agreements with California and Mexico to obtain desalinated water.

“I think the ability to adapt is very high,” Megdal said.

But for a more durable solution, Udall said existing agreements and water rights would need to be overhauled to reflect reality.

“We need to agree on how to share the water we have without pretending to live in the past,” he said. “We have to adjust this system to deal with a whole new reality of significantly reduced water flow. We have to make ends meet here.”