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Q&A: Snow droughts imperil the American West’s water supply

By
Mitch Tobin
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A thin snowpack covers Engineer Mountain, in the San Juan Mountains of southwest Colorado, on February 2, 2025. The region suffered a significant snow drought this season. Photo by Mitch Tobin/The Water Desk.

In recent years, scientists and water managers have started using the term “snow drought” to describe meager snowpacks in the American West. 

A snow drought can come about in two main ways. A “dry” snow drought happens when not enough snow falls, leading to a diminished snowpack. A “warm” snow drought occurs when precipitation is near or above normal, but higher temperatures cause raindrops to fall instead of snowflakes, or when warm weather causes the snowpack to shrink rapidly.

Because a lack of snow has such profound implications for the West’s water supply, wildfire risk, recreational activities and ecosystem health, the federal government now regularly tracks the severity of snow drought across the region.

The reports rely on data from hundreds of SNOTEL stations—a network of automated sensors that use “snow pillows” to weigh the snowpack and calculate its water content—but federal budget cuts may hamper that system going forward. 

To learn more about snow droughts, I recently spoke with one of the authors of those reports: Dan McEvoy, regional climatologist at the Western Regional Climate Center and the Desert Research Institute.

The Q&A below contains excerpts from my conversation with McEvoy, edited for clarity and brevity.

Dan McEvoy, regional climatologist at the Western Regional Climate Center and the Desert Research Institute.

What is a snow drought? How is it defined?

Snow drought, in its simplest form, is just a snowpack deficit, or less snow than there should be for a given time and place, and it all is relative to that local place, wherever it might be. 

This concept of snow drought is not new. There’s been a connection for a long time in the Western U.S. between snow and water and drought. But I think what is new is (that) the term snow drought was not really used commonly for a while, up until maybe six, seven years ago, when the research really picked up. 

I will say there’s not really a single agreed-upon definition of what a snow drought is. If you look in the literature, there have been several different ways to define it. 

Some studies will use April 1st snowpack or the peak snowpack and look at the anomaly during that time. Other work that I’ve contributed to took a different viewpoint and brought up this idea that we should be looking at snow drought daily as it evolves throughout the season, so tracking snow droughts from the beginning of the season to the end of the season through time. And so, in that sense, you could have an early-season snow drought and come out of it in the middle of the year, or the opposite: start off well and then go into a snow drought later in the year.

Something fairly common to use in terms of defining snow drought is a percentile-based method—where does the snowpack value fall in the historical distribution? And this is common in other definitions of drought, particularly the U.S. Drought Monitor uses a percentile threshold. So, for example, anything below the 20th percentile would be considered in a snow drought, and then there’s varying categories. 

I guess I should step back and say that the variable that is the most common thing with a snow drought is the snow water equivalent (SWE), which is the amount of water that is in the snowpack at any given time.

Is it a problem or a challenge that different researchers are using different definitions?

I don’t think it’s a problem. I think we’ve seen this in other areas of drought, especially. I don’t know if you’ve heard of the term “flash drought,” but that’s another one that’s a bit older in terms of the research that’s been done, where there was never really a single agreed-upon definition. And I think that’s because the research is still ongoing to fully understand what a snow drought is and what it means. 

It is good to have an agreed-upon definition if it comes down to using it for something like operational monitoring or a trigger for a drought emergency or a water shortage or something like that. But I think what we’re seeing in the literature is that the varying definitions are trying to get at different aspects of snow drought. And so I think it’s a good thing in a way. Perhaps down the road a bit, there might be a more agreed-upon singular definition, but it’s been very interesting to see how different research groups are trying to look at snow drought.

What are the practical implications of a snow drought? Who and what is affected?

I think the clearest connection with snow drought is related to water supply in the Western U.S. Snow drought is less snow than you should have, and our snowpack provides the majority of our freshwater surface water supply in the Western U.S., and so very often snow drought years are associated with lower-than-average runoff into streams and reservoirs, and then that can lead to further drought development in the summer months. In those snow drought updates, we try to pinpoint any specific impacts. 

I think the research community is trying to unpack what a lot of these other impacts are. One that I’m interested in is in a snow drought year, you’ll often have a shorter snow season and the snow will melt out earlier than it would in an average year. And so that leaves the landscape and the ground and the vegetation exposed longer, when it would normally be covered in snow longer. And so this gets to the soils drying out quicker, the vegetation either greening up earlier and then drying out earlier, or just drying out quicker, and connecting that to wildfire danger impacts later in the summer. I think there’s a general consensus on the agreement that lower snow tends to increase fire danger in the summer, but there hasn’t been extensive work really getting into the weeds on that. 

Another question that has come up that there haven’t been a lot of answers to is the more ecological impacts related to snow drought. I guess vegetation is one of those, but things like animals that depend on snow cover—that hibernate or depend on that snow cover for protection and insulation—and kind of understanding more about the ecological impacts related to snow droughts. That’s also something I’m interested in that I don’t think there’s a good answer to. So there’s some known impacts and I think still quite a few unknown impacts related to snow droughts.

We’ve seen all of these federal cutbacks in terms of monitoring and science agencies. Is that affecting your ability to monitor the snow drought?

The short answer is not right now, not immediately, but there’s a lot of concern. The biggest one is around cuts to NRCS [Natural Resources Conservation Service], which have already happened in some places. They’re the ones that install and maintain the SNOTEL network. The stations themselves aren’t going to just completely disappear. No one’s going to go out there and remove them. Of course, that would require staff to even do that. But the concern is that every single one of those gets at least maintenance once a year, if not twice a year by these NRCS staff. And that maintenance is what keeps the data high quality, making sure the stations are calibrated, functioning properly. 

The other aspect is (that) the NRCS (does) manual QC [quality control] of the data. So people at the various offices actually look on a daily basis at the data streams coming in. They have an automated QC process, but they know that doesn’t catch everything, and so they actually have people going through these data streams, because the data transmits at hourly timescales and they actually look through that to make sure the daily values that show up are accurate. There’s people on a daily basis doing that data QC, and so a big concern is that we will see degradation of the instrumentation and the quality of the measurements as well as the data streams and the QC, basically leading to less reliable and less accurate snow measurements. So that’s a big concern. I haven’t seen an immediate impact yet, but we know that there have already been big losses at NRCS. The maintenance season is the summer, after the snow melts and they can get out there, so we may not see those impacts until the start of next winter when we go to start looking at the snow data again.

A SNOTEL station on Coal Bank Pass in the San Juan Mountains of southwest Colorado on October 21, 2024. Federal cutbacks could affect the maintenance of the automated sensors and the quality of data they produce. Photo by Mitch Tobin/The Water Desk. 

What is the connection between snow droughts and climate change? 

There’s a general consensus and there’s good literature showing that since 1950, overall, the snowpack in the Western U.S. has been declining—more so in some places than others. That’s primarily due to warming and climate change. And so just that alone suggests that we will continue to see more frequent snow droughts, because again, a snow drought is less snow than you normally would have at any given time. There has been some research showing future projections that go out to the end of the century. Adrienne Marshall has a really nice paper that shows the peak SWE is projected to continue to decline, and there’s a much higher likelihood of seeing two snow drought years in a row.

(See my 2024 Q&A with Marshall on snow deluges, which are the opposite of snow droughts. McEvoy also cited an influential 2021 paper with an ominous title—“A low-to-no snow future and its impacts on water resources in the western United States”—that projected steep snowpack declines due to climate change.)

If we kind of continue on this warming path that we’re on, the snowpack is likely to continue to decline. That includes more rain and less snow in the mountains. So that would mean probably more warm snow droughts as opposed to just dry snow droughts as annual and water-year precipitation trends aren’t necessarily changing all that much, depending on where you are. And so a lot of that decline is going to be due to warming temperatures and more rain.

“Relative to today’s climate, I think there’s definitely an expectation of seeing more snow droughts in the future.”

What about predicting snow droughts? Are there early-warning systems or are there ways to look ahead to know that one is coming or building?

I think explicitly predicting snow droughts is still not being done right now. An early-warning system gets to kind of the elements of what we’re doing with the snow drought updates. It’s kind of staying on top of tracking it throughout the season, so water users or land managers aren’t just caught off guard when you get to midseason or late season and realize that the snowpack’s much lower than it should be. 

Long-range and seasonal temperature and precipitation forecasts are commonly looked at, although once you get beyond about two weeks, there’s not a whole lot of reliability there. And so I think it really is still a huge challenge in trying to predict the snow drought even at the start of a season.

When flows are low, river recreators seek out new allies and avoid making enemies

By
Luke Runyon
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The Yampa River meanders outside of Craig, Colo. on May 12, 2025. The city is one of a few small communities that line the mostly rural waterway. (Luke Runyon / The Water Desk)

What used to be a calm stretch of the Yampa River near Craig, Colorado, now boasts a new set of rollicking whitewater rapids. 

They’re not the result of some new rockslide. The boulders in these rapids were selected to create just enough splashy holes to attract kayakers, and they act as the focal point of the city’s new effort to draw residents and tourists down to the river’s banks. 

On a breezy spring afternoon Melanie Kilpatrick, the project manager overseeing the construction of the new Yampa River park, stood along its banks as large earthmoving machinery prepped more large boulders for placement in the river channel. 

“I’ve always felt like the Yampa has been an underutilized asset in the area,” Kilpatrick said, noting that the river hasn’t always been seen as a recreation amenity. It flows to crops and through the nearby coal plant. But its ability to generate tourism dollars was underplayed, she said. Just getting down to its banks has been a challenge. 

“I may have come to tube the area, but access is very rough and rustic,” Kilpatrick said. 

Craig, a city of 9,000 residents in Colorado’s northwest corner, is facing a big transition. The local coal plant is slated for closure in a few years. The ensuing economic anxiety sent its leaders looking to diversify and establish a new draw for tourists. They decided to double down on becoming a recreation hub for the region, centered on the Yampa River, which flows through town. 

The Yampa River Corridor Project is set for completion in October. It boasts new rapids, an established boat ramp and improvements to the city’s drinking water infrastructure.

But unlike officials in other Colorado communities, Craig officials have so far chosen not to pursue a water right to support this new recreation amenity.

The city of Craig’s Melanie Kilpatrick oversees construction of the new Yampa River Park on May 12, 2025. It’s slated to open later this summer. (Luke Runyon / The Water Desk)

The Yampa’s flows are notoriously hard to predict, and rather than ruffle feathers with other local users, the city has tabled discussion over what is known as a recreational in-channel diversion, or RICD. The right can hold a place in line in Colorado’s water appropriation system and gives legal standing to the cities and towns that invest in whitewater parks. If exercised, an RICD could force another water user on a stream to stop diverting in order to preserve flows for recreation alone. 

In the arid West, a hierarchy of water users has long favored agricultural and municipal uses, some of the first major uses to come online during the region’s colonization. Newer uses that embody the Southwest’s changing values — uses such as incorporating water to support ecosystems or to boost recreation — have had to weave their way into that more traditional, inflexible system. And recreation advocates are often trying to forge new alliances with traditional users to further their aims or to avoid causing undue friction among their fellow users. 

In the design and construction of the city’s new whitewater park, Craig’s leaders considered obtaining an RICD but aren’t ready to pull the trigger, Kilpatrick said.

“We were very mindful about flow levels, but also just, you know, concerned about what’s happening on the horizon,” Kilpatrick said. “We can’t design this massive park if we don’t have the flows to support it. And that’s not what we intended to do. We wanted to build something that would naturally integrate in the flows that we anticipate to see now and in the future.”

Part of the city’s calculation is that in the short term, there’s a good chance that the existing water rights structure on the Yampa will end up benefiting the park even without any additional protections. Large users with older water rights sit downstream of Craig. When those farmers and ranchers call for water through the river channel, it ends up flowing past the city anyway, boosting its flow. The same goes for additional flows to protect endangered fish species farther downstream that can happen throughout the spring and summer months.  

But even with a rosier short-term outlook for flows, Kilpatrick said there is growing concern about the Yampa’s viability in a warming, drying world. Eventually, she said, there could be a good reason to apply for a recreational water right. 

“I think at least keeping that dialogue going is going to be an important factor as we kind of determine, as a community, whether that’s something we approach or not,” she said.

The Yampa River Park begins to take shape in Craig, Colo. on May 12, 2025. Facing an impending closure of its nearby coal plant, the city has invested more in recreational opportunities to draw tourists and new workers. (Luke Runyon / The Water Desk)

Meeting multiple needs at once

It’s a similar story a couple hours’ drive south in Grand Junction, where a meandering side channel flows off the Colorado River, ready for tubers and stand-up paddleboarders. Over Memorial Day weekend, dozens of people splashed and swam along the banks to cool off amid temperatures in the mid-80s. 

“It’s a great amenity for the city of Grand Junction and the whole valley to get to come down and experience the river in a way that wasn’t really accessible before,” said Hannah Holm, associate director for policy for the advocacy group American Rivers. 

The side channel is relatively new and gives residents a safer way to come play in the swift-moving Colorado. The river through town can drop very low in the summer — too low to comfortably raft it at times — as farmers draw water away to grow crops. Here, too, recreational use often holds a lesser legal standing. Water isn’t guaranteed to flow all summer long through this side channel, even in very wet years.

A reach of the Colorado between the large diversion structures that take water off its main channel to its confluence with the Gunnison River has long been a focal point for recreation advocates who want to see more robust flows through town in the summer. 

“So, we do have some water rights that are supposed to protect those values, but they’re very junior, and sometimes, sometimes, they come up short,” Holm said. 

Hannah Holm of the advocacy group American Rivers stands along a slow meader of the Colorado River in Grand Junction, Colo. on May 13, 2025. (Luke Runyon / The Water Desk)

But much like portions of the Yampa, additional flows happen here for other uses — and recreation just happens to benefit as well. The reach through Grand Junction often is boosted to help endangered fish habitat or to generate hydropower at a nearby plant. That extra water also makes for good floating in rafts, kayaks and tubes. Getting limited water to benefit more than just one type of water user requires cooperation among all of them, Holm said. 

Holm says it’s possible for the strained Colorado River, and its main tributaries, to meet multiple needs at once — it just requires all of the different groups who use its water to talk to one another.

“We need to avoid a crisis on the river first of all, because when you get into a crisis, you just, you know, make decisions on the fly,” Holm said. She added that emergency releases from some large reservoirs in 2021 to boost levels at Lake Powell could have been optimized to take place at the height of the summer recreation season or to have environmental benefits. 

Abby Burk of Audubon Rockies stands on the banks of the Colorado River in Grand Junction, Colo. on May 13, 2025. (Luke Runyon / The Water Desk)

But even with good cooperation, at a certain point with rapidly changing water levels, river recreators need to take matters into their own hands. 

Abby Burk, a kayaker in Grand Junction and a river policy expert with Audubon Rockies, said that since snowmelt causes rivers to rise and then fall, sometimes it’s a matter of matching the vehicle to the flow.

“We see the transformation from maybe getting out on a raft to maybe getting out in an inflatable kayak, and then maybe in really low waters, getting out on a tube and just enjoying your local river at its water level,” Burk said.

In Craig, Kilpatrick said such a mindset is present in the design of the town’s new river park. Even without a specific water right on the Yampa right now, she said she’s confident about making sure it’s fun at all levels, and could spur a whole new recreation-based economy to take off in town. 

“It really gives us an opportunity to kind of reinvent ourselves as what we want to be as a community,” Kilpatrick said. 

This story is part of a series on river recreation in Colorado, produced by Aspen Journalism, KUNC and The Water Desk at the University of Colorado Boulder. 

Colorado communities have spent millions of dollars on whitewater parks. Are they worthwhile?

By
Heather Sackett, Aspen Journalism
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Early-spring runoff flows through the Roaring Fork River whitewater park in May. The park has been adjusted to make some features safer in higher water. (Heather Sackett / Aspen Journalism)

There’s an old catchphrase that Colorado kayak park proponents used in the early 2000s to sell the idea that keeping water in streams mattered just as much as water for big farms or new housing developments: “The greater the flow, the greater the dough.”

“You would have thought it was an Economics 101 class,” said Glenn Porzak, a Boulder attorney who worked on behalf of the city of Golden and the towns of Breckenridge and Vail to secure the state’s first water rights for recreation. 

Some towns saw these recreational in-channel diversions, or RICDs, as a way to boost tourism dollars and spur economic development by drawing kayakers and spectators to a whitewater park. So, giving legal standing and recognition to a growing sector of Colorado’s economy — outdoor recreation — was the argument that legal experts focused on.

“The Golden course started somewhat of a transformation of downtown Golden, bringing people into the downtown area, and so we really went in and talked about the economic benefit,” Porzak said.

Unlike other traditional uses of water that require taking water out of streams — such as irrigated agriculture, cities and industry — a RICD isn’t really a diversion at all. It is meant to keep water in rivers by tying a water right to a manmade river feature, most commonly the waves in whitewater parks. 

More than two decades after Porzak helped the city of Golden acquire the state’s first RICD, 21 local governments in Colorado now have water rights for recreation. About half of these towns have built whitewater parks around these water rights. The Town of Vail’s RICD has been an integral part of the GoPro Mountain Games, an early-summer celebration of mountain sports competitions, with four kayaking events in the whitewater park in Gore Creek. 

Vail’s RICD, which the town secured through the Eagle River Water and Sanitation District, dates to 2000. Instead of building immovable concrete structures in the river, as many other communities have done, the Vail Whitewater Park has a series of adjustable, inflatable bladders that create waves at different flow levels. The games draw thousands of athletes and spectators to Vail each June. And a popular Tuesday night race series brings kayakers from around the region.

But determining the value that these RICDs — or river recreation in general — bring to the state’s outdoor economy is difficult. According to the Colorado River Outfitters Association, the total industrywide economic impact for 2023, the most recent year for which data is available, was $215 million. But that figure is only from commercial river trips.

“We don’t have good numbers on economic benefit data coming from private use,” said Nathan Fey, former director of the Colorado Office of Outdoor Recreation and former Colorado stewardship director at American Whitewater. “People come from all over the West to spend money on gas and food and beer and ice, and those numbers are never captured in an economic impact report.”

Kayakers paddle down Slaughterhouse Falls on the Roaring Fork River on June 15, 2021. Changes to Colorado water law in the early 2000s gave river recreation advocates a stronger voice in keeping streams flowing. (Heather Sackett / Aspen Journalism)

Protection from future water development

Some say the value of a recreation water right can’t be measured in dollars, but it’s a legal tool that can be used in other ways. One could be to prevent future water development on a particular stream. 

For Pitkin County Healthy Rivers, the main goal of securing a RICD water right for two manmade waves in Basalt was always to keep water in the Roaring Fork River. 

Boater and retired science teacher Andre Wille has been on the Healthy Rivers board, whose mission is to improve water quality and quantity, since its inception in 2008.

“It is true that we weren’t looking to build a whitewater theme park that was just to draw in boaters,” Wille said. “Our primary goal was to get this water right that would keep water in the Roaring Fork in perpetuity.”

The Pitkin County River Park was one of the biggest and most expensive multiyear projects that the board has undertaken. Keeping water flowing west is an especially important goal for Pitkin County and the communities along the Roaring Fork because about 40% of the river’s flow is taken from the headwaters in what’s known as a transmountain diversion, to be used by cities and farms on Colorado’s fast-growing Front Range. 

“The transmountain diversions are one of the biggest threats because of the amount of water that they can divert,” Wille said.

Securing a RICD saves a place in line for recreational water use in Colorado’s system of prior appropriation where the oldest water rights get first use of the river. Therefore, Pitkin County’s RICD could limit how much additional water transmountain diversions can take from the Western Slope in the future because this water is already spoken for.

Pitkin County Healthy Rivers Board member Andre Wille stands on the banks of the Roaring Fork River in May. The county’s recreational water right was an attempt to keep more flowing in the river. (Heather Sackett / Aspen Journalism)

Challenges and limitations

But the road to a RICD hasn’t been easy for Pitkin County. The county has spent more than $3.5 million on the park, an amount that included, among other things, building the waves and then modifying them twice after high flows turned them into dangerous holes that regularly flipped boats. 

“We’re doing our best to make it safe,” Wille said. “But at high water, the river changes dramatically, and things that you would never think are dangerous suddenly become dangerous.”

Part of this is simply the unpredictable nature of building concrete features in a dynamic river channel. But it also highlights the limitations of a RICD water right, which must be tied to an artificially constructed wave instead of a naturally occurring rapid or stretch of river. If communities want water for recreation, they must build the costly waves themselves. 

“I think the current statute is a bit archaic,” Fey said. 

In 2021 and 2022, American Whitewater and other groups twice lobbied the state legislature to expand this narrow definition. First, they proposed tying a RICD to an already existing natural river feature such as a rapid; the next year, they sought to allow municipalities to create a “recreation in-channel values reach,” where they could then lease water to boost flows in the segment during certain times.

These were attempts to adapt the RICD statute to new forms of river recreation — mostly day floats on sections of rivers — that have outpaced the popularity of kayak playboating in whitewater parks.

“The early aughts to, like, early 2010s was where that type of whitewater recreation was popular, this rodeo surf river feature,” said Hattie Johnson, southern Rockies restoration director with American Whitewater. “We’ve seen kind of a big shift away from that.”

But Colorado lawmakers weren’t convinced that the RICD statute should be changed. Both bill proposals failed.

American Whitewater’s Hattie Johnson stands along the Crystal River in May 2025. (Heather Sackett / Aspen Journalism)

In some cases, if a local government wants to secure a RICD, it must also make concessions to future water users by agreeing to allow a certain amount of development before they can exercise their legal authority to call for water. In Pitkin County’s case, officials agreed to allow 3,000 acre-feet of additional water development to cut them in line. That cap was reached in 2024, effectively pushing the county’s priority date back 14 years from when it filed for the rights in 2010.

Fey said these types of “carve-outs,” which allow for future water development, go against the cornerstone of Western water law: the system of prior appropriation, also called first-in-time, first-in-right.

“There is a subordination clause in many of the decrees associated with RICDs,” he said. “That’s a point of contention for a lot of people in the river conservation space that look at RICDs as a tool for long-term protection.”

Besides limiting future water development, the main way a RICD can keep water in rivers is by using its legal authority to force others to stop using water. When a water right isn’t getting all the water to which it is entitled, it can place what’s known as a call and force upstream junior water users to cut back. The problem is there aren’t that many big water rights younger than RICDs — which carry dates from the late 1990s to 2013 — that could cut back enough to make a difference. 

None of the 13 RICDs on the Western Slope have ever placed a call, according to the state Division of Water Resources.  

“[RICDs] are very, very close to the end of the line, which means all other uses that are more senior to that date get their water first,” Johnson said. “So the utility of a recreational in-channel diversion really comes in to protect that reach of river from further development.”

Are RICDs worth it?

With all these expenses, challenges and limitations of RICDs — and the difficulty of directly quantifying their economic benefit — it’s worth asking whether they have proved worthwhile for the communities that have gone to the trouble of securing them.

Johnson said the real value of RICDs is in giving a voice to the river recreation community. They may be an imperfect tool, but they are an important one. For the first 150 years of Colorado water management, agriculture and cities held all the decision-making power when it came to how water was used. That may be slowly changing as outdoor recreation becomes more important to Colorado’s culture, identity and economy. 

RICDs have expanded cultural perceptions of how Colorado’s water is best used, and water for recreation is now an acknowledged beneficial use of a public resource.

“Both the environment and recreation are extreme newcomers to that table, but have a seat now,” Johnson said. “I think RICDs have helped to do that.”

Despite the challenges and limitations of a RICD water right, Wille said building the Pitkin County River Park was still worth the expense to taxpayers. He feels good about the county’s effort to protect river flows as it confronts a warmer and drier future, and water becomes scarcer.

The project also included upgrades to the Fisherman’s Park boat ramp, a new boardwalk and tiers of large streamside boulders where people can lounge or eat lunch next to the waves. The park represents a connection between the community and its local waterway. 

“It’s been, I think, a very wise investment and a very good use of our fund that we have for protecting rivers,” Wille said. “That’s one of our goals: to try and acquire water rights and keep water in the river. This is one of the few ways that we’ve been able to do that. So, yes, I think it’s been money well spent.”

This story is part of a series on river recreation in Colorado, produced by Aspen Journalism, KUNC and The Water Desk at the University of Colorado Boulder.

The Water Desk announces grants for coverage of the Colorado River Basin

By
The Water Desk
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The San Juan River, a major tributary of the Colorado, snakes through canyons in southern Utah. (Mitch Tobin / The Water Desk)

The Water Desk is now accepting applications for grants of $5,000 to $10,000 to support media outlets and individual journalists covering water issues related to the Colorado River Basin.

The deadline for applications is Monday, June 16, 2025, at 11:59 pm Pacific.

This grantmaking program is only open to journalists (freelance and staff) and media outlets.

The Water Desk is interested in supporting a wide variety of media and journalistic approaches: newspapers, magazines, websites, video, television, radio, podcasts and other channels.

The Water Desk will support journalism that focuses on water issues involving the seven states of the Colorado River Basin—Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming—as well as the borderlands of Northwest Mexico.

Proposals related to areas that lie outside of the hydrologic boundaries of the Colorado River Basin’s watershed must have a strong connection to the basin and its water resources.

Because water is intertwined with so many issues, we are open to proposals covering a broad spectrum of topics: climate change, biodiversity, pollution, public health, environmental justice, food, agriculture, drinking water, economics, recreation and more.

Funding for these grants comes from the Walton Family Foundation. As a journalistic initiative, The Water Desk maintains a policy of strict editorial independence from our funders, as well as from the University of Colorado Boulder. Funders of The Water Desk have no right to review nor influence stories or other journalistic content that is produced with the support of these grants.

Our grantmaking page has more details about the program. You can apply on this page.

Questions? Please contact Water Desk co-directors Mitch Tobin (mitch.tobin@colorado.edu) or Luke Runyon (luke.runyon@colorado.edu).

Colorado has unique protections for river recreation, but do they have enough legal muscle?

By
Alex Hager, KUNC
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David Hajoglou paddles through the Clear Creek Whitewater Park in Golden, Colorado, on April 21. Recreators hold special legal protections in the state, but some say it’s time for the law to evolve. (Alex Hager / KUNC)

David Hajoglou sat on the rocks next to a rushing stretch of river in Golden, Colorado. As he scouted a kayak route through the riffles and waves, he thought back to the first time he visited this spot, the Clear Creek Whitewater Park, nearly 20 years ago. 

“Boy howdy, did it kick my butt,” he said. “I swam a few times. I chased a kayak probably all the way to 10th Street there, whatever the cross street is, and it was just a riot.”

Hajoglou — better known as Hojo in the local kayak scene — has come back to this stretch of Clear Creek more times than he can count since that first rowdy run through the waves. And since then, the park has grown in stature. 

It’s a series of rocks strategically placed in the river to create waves, pools and eddies that form a watery playground for kayakers such as Hojo. It holds a legendary status among Colorado’s paddlers and river advocates. This stretch of Clear Creek was the first to receive legal protections that guarantee a certain amount of water will always flow through it. That was the result of a high-profile legal battle nearly 25 years ago.

Those protections gave recreators some legal footing — the same kind of status long held by cities and farms. As a result, they helped put Colorado on the map as a destination for people who want to play in rivers.

That rings true for Hojo and other kayakers. 

“The second you get hooked on it,” he said, “you look at this park and you get excited for the prospect of getting on moving water. It’s very addicting.”

In the more than two decades since the courtroom showdown that set up protections for water used by recreators, more than a dozen whitewater parks have been built across the state. Now, river advocates are asking if those protections should change to meet the moment.

Sunbathers and kayakers enjoy Clear Creek Whitewater Park in Golden, Colorado, on April 21. The park was the first in the state to receive protections for river recreation after a high-profile legal battle in 2001. (Alex Hager / KUNC)

Making room for boaters

If you have ever questioned how seriously Colorado takes its water, let attorney Glenn Porzak tell you about the time he went to the Colorado Supreme Court in 2001. He was arguing for the protections that would make today’s Clear Creek Whitewater Park possible

“When I walked in, every seat in the Supreme Court chambers was taken,” he said. “They brought in a whole host of extra chairs. There were people just standing in the aisles.”

Porzak, now a veteran in the Colorado water law scene, was there to push back on the state’s attempt to outlaw recreational water rights. Cities around the state were looking at a sharp rise in the popularity of whitewater kayaking, and they were trying to draw people to their rivers. But first, they needed to make sure the water wouldn’t stop flowing because someone upstream wanted to pull that water away. 

The Colorado Water Conservation Board (CWCB) was worried that adding recreation into the already contentious arena of water ownership would upset the status quo.

“They really saw this as a threat,” Porzak said. “You would think, in a state like Colorado, water for these various recreation uses … would be something that the state would really embrace. But I’ve never believed that that was the case.”

Porzak’s side won, enabling a boom of those so-called whitewater parks. If a Colorado city wants to bring kayakers and their money to town, they can throw some big rocks in the river and apply for a “recreational in-channel diversion,” or RICD. Basically, if the river is ever close to flowing too low for boaters, they could have the legal muscle to force upstream users to leave some water in the stream.

Time to evolve

These legal rights are limited in their capacity. They cannot add water to the river. They can tell other users to stop taking water out of the river. An RICD does not necessarily improve river conditions for recreational water users, but it makes sure they don’t get worse in the future. 

Basically, it can play defense, but not offense. 

Despite that ability to play defense, RICDs rarely flex their legal muscles. In the two and a half decades since recreational water rights holders have had the option to force another user to leave some water in the river, only three of Colorado’s 21 holders have ever done so.

Taking that option is called “placing a call.” The Clear Creek park in Golden did it for about two weeks in 2005. Longmont did it in 2023 and 2024, and Littleton has placed a call for at least a few days every year since 2016. None of the RICDs on the Western Slope have done so.

Kids play in the Poudre River Whitewater Park near downtown Fort Collins, Colorado, on Oct. 20, 2023. Some river advocates say legal protections for Colorado’s rivers should be expanded to include types of recreation that don’t hinge on whitewater features. (Alex Hager / KUNC)

Hattie Johnson, southern Rockies restoration director at the advocacy group American Whitewater, called the RICD designation a “necessary and important first step.”

“I would really like to see the state continue to evolve to really meet the realities of what recreation is like on Colorado’s rivers,” she said. “And I think there’s plenty of room for that evolution to happen.”

Johnson and other river experts think that evolution could happen in a few ways. Most of them have to do with making it easier to get a recreational water right.

Right now, for a nonstate entity to get any kind of water right, there is a legal requirement to divert the river or somehow change the flow of water. That’s why recreational water rights in Colorado are tied to whitewater parks, where rocks are used to modify the river’s course.

Kate Ryan, who has worked in Colorado water law for more than a decade, said putting boulders in the water in order to establish a protected stretch of river “seems like a legal fiction.”

“You just have to do something to the river in order to get a water right,” she said. “That just doesn’t seem practical, and it’s really expensive. I think that could go away.”

These river parks often attract more than kayakers. Visit any one of the stretches of river protected by a RICD and you will probably see swimmers, tubers, toe-dipping sunbathers and the occasional angler.

Those people are able to access protected stretches of river as a convenient side effect of the RICD laws. Ryan, now executive director of the Colorado Water Trust, said protections should be expanded to include a broader definition of “recreation.”

“You can go put your foot in the stream in lots of places,” she said, “But you don’t have a way of preserving that right into the future.”

Ryan and others also suggest lowering the barrier to get a RICD in the first place. Currently, anyone looking to get legal protection for their water needs to go to the state’s water court. That’s a standard practice for any kind of water user in the state – whether they’re hoping to open a kayak park, irrigate crops or send water through their town’s kitchen faucets. 

Kayakers gather at the float course in Longmont, Colorado, on May 9. Although legal protections for river recreation are relatively weak now, experts say they will probably get more powerful in the future. (Alex Hager / KUNC)

But there’s an extra hurdle that most types of water users don’t face. Applicants for a RICD also have to answer a long list of questions for the CWCB — the state’s top water regulator.

“We haven’t had RICD applications in a pretty long time,” Ryan said. “So there must be a pretty high bar that’s been established to keep more of the entities who could apply for them from applying for them. … Nobody wants to go to water court for anything. It’s just incredibly expensive and time consuming. I think adding an administrative layer onto that is too much — possibly unconstitutional.”

Saving a spot in line

Despite the relative legal toothlessness of RICDs, river experts say they will get more powerful in the future. 

Water law in Colorado and much of the arid West is governed by the concept of “prior appropriation.” It basically means that the first person to use water will be the last to lose it in times of shortage. If you were first in line, your access to a specified quantity of water is almost legally untouchable. People who were granted the right to use water more recently are at the end of the proverbial line and are required to stop using their water first. 

RICDs give their owners a place in that line. 

Although most RICDs are relatively junior to other users in the state, more new users will probably get in line behind them as time goes on. 

The city of Steamboat Springs owns an RICD to protect some popular river recreation spots along the Yampa River. It has never put out a call, but it knows that it might have to if someone new wants to take water from the river. 

“I think that the RICD will become a more important tool in the toolbox and an option that the city could potentially exercise in the future,” said Julie Baxter, Steamboat Springs’ water resources manager.

Baxter also pointed out that the RICD will become more powerful if another force removes water from the river: namely, climate change. With less water to go around, anyone with a legal claim to the river will have some added muscle to keep their water flowing.  

“I think it will become more important down the road with a hotter and drier future,” she said.

This story is part of a series on river recreation in Colorado, produced by Aspen Journalism, KUNC and The Water Desk at the University of Colorado Boulder. KUNC’s Colorado River coverage is supported by the Walton Family Foundation.

Scientists use cosmic rays to study the snowpack

By
Mitch Tobin
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Researchers prepare to take readings of the snowpack in Colorado’s San Juan Mountains to ground-truth a cosmic ray neutron sensor. Photos by Mitch Tobin.

Red Mountain Pass, Colorado – 

Cosmic rays come from outer space.

These high-energy particles, which emanate from the sun but also from beyond our galaxy, travel across the universe, nearly at the speed of light, to reach Earth. 

Our atmosphere and magnetic field shield us from cosmic rays, but secondary particles shower down and reach ground level. These particles are harmless to us, but some of them interact with water at the Earth’s surface and can provide important data on how wet or dry the local conditions are. 

For years, cosmic rays have been employed to measure soil moisture. Now, high in the San Juan Mountains of southwest Colorado, scientists have been investigating how to use cosmic ray neutron sensors to calculate the water content of the snowpack, known as snow water equivalent (SWE).

SWE (pronounced “swee”) is of keen interest to water managers, irrigators, rafters and many others downstream from these high-country frozen reservoirs, which serve like mountain water towers but are vulnerable to warming temperatures due to human-caused climate change.

On a recent snowy morning, I tagged along with three researchers who were taking readings of cosmic ray neutrons with a mobile sensor known as a rover. They also ground-truthed the nearby snowpack by measuring its depth and density to calculate its water content. 

Using cosmic rays has the potential to provide much more data on SWE than traditional approaches that measure the snowpack at a single point because this novel method gauges the water content over a far larger area.

The researchers gauge the water content of the snowpack by measuring its depth and density (click to enlarge photos)

In the prior 24 hours, nearby Silverton Mountain ski area had reported 14 inches of new snow. Up around Red Mountain Pass, there was at least that much, and the fresh layer made it tough to get around, even on snowshoes. The temperature on my dashboard read 10 degrees, and the snow sometimes blew sideways, sending the wind chill well below zero. 

“Basically, the goal of our project is kind of to see how well this rover is at estimating SWE,” said Christina Chow, a graduate student at Colorado State University whose thesis is looking into the benefits and limitations of the rover for use in water resource management. 

Nearby, the $70,000 cosmic ray neutron sensor sat in metal cabinets in the back of a hatchback, quietly doing its thing.

The cosmic ray neutron sensor fits in the back of a hatchback and provides data on the water content of the nearby snowpack.

The researchers drove the system along U.S. 550 at a steady 25 mph to take readings of the snow surrounding them. The scenic road, also known as the Million Dollar Highway, attracts tourists from around the world, especially during the warmer months when driving conditions on the serpentine path are less of a white-knuckle affair. 

At a few points along the highway, the trio of researchers stopped to take measurements of the surrounding snowpack.

One of the crew’s tasks was using an app on their phones to measure the dimensions of the snowbank beside the highway so that it could be factored into the calculations derived from the sensor. In some places, snow plows and heavy machinery had concentrated the snow into towering masses that were downright challenging to climb. 

The researchers had to navigate and map tall snowbanks along U.S. 550, also known as the Million Dollar Highway

The researchers also fanned out from the road to take readings of the snow depth and used a hollow tube to extract a core of the snowpack. That snow was then emptied into a plastic grocery bag and weighed in order to calculate its density and the SWE.

The tasks seemed challenging given the working conditions–my fingers were frozen even inside gloves–but the trio seemed in high spirits. 

“It’s awesome to be out here,” Chow said. “We’ve had a couple cold days, so that’s been challenging, just to kind of warm up and everything, but, yeah, it’s been a blast.”

The rover takes a weighted average of the snowpack with a radius of about 200 meters (656 feet), so it provides data on a large area compared to traditional methods of measuring the snowpack at individual points, both by hand and with automated sensors known as SNOTEL stations. 

“This is actually measuring SWE,” Chow said. “Not a lot of things can do this at this scale . . . it’s not at a point scale. It’s at this big, big footprint.”

SNOTEL stations remain the backbone of monitoring the mountain snowpack in the West and may have decades of data to analyze, but they’re fixed in space and don’t register how wind, shade and other factors may alter snow accumulation nearby. 

While it’s convenient to drive with the rover on a highway, “the road has a signal that we have to account for,” Chow said. 

Was the snowfall we were experiencing influencing the activity of the cosmic ray neutrons?

“We’ve been thinking about that a little bit. I’m not entirely sure,” Chow said. “Snow in the atmosphere will slow neutrons as well, so I’m sure it has some sort of signal.”

Another challenge? The complicated science behind cosmic rays.

“I’m still trying to get my head around all the nuclear physics,” Chow said. 

From cosmic rays to soil moisture, by IAEA

So about those cosmic rays. They were first discovered in 1912 through experiments using a high-altitude balloon that earned physicist Victor Hess the 1936 Nobel Prize. The term “cosmic rays” was coined in 1925 by Nobel laureate and former University of Chicago faculty member Robert Millikan, according to this piece by the school, which notes:

“In the 20th century, cosmic rays helped scientists discover antimatter and the muon—the first evidence for subatomic particles beyond the proton, neutron and electron. Cosmic rays can also tell us about the chemical and physical makeup of the universe; about how the universe has changed over time; and what happens around supermassive black holes and in the hearts of exploding stars.”

The word “ray” is a misnomer because they’re actually high-energy particles. Here on Earth, the sun is considered the main source, but scientists have also documented them coming from galaxies beyond the Milky Way.  

An artist’s rendering of a cosmic-ray air shower, developed in connection with a 2017 paper in Science. The paper argued that some cosmic rays come from beyond our galaxy. Source: EurekAlert!

The cosmic rays that hit our atmosphere produce fast, high-energy neutrons that are able to reach the snow and underlying soil. There, they interact with water molecules, in particular the hydrogen atoms, causing some of the neutrons to be slowed. If the sensor detects fewer fast neutrons, that means there’s more hydrogen–and water–in the area.

“In simplified terms, the lower the neutron count, the higher the presence of water,” according to a summary of the project in the San Juans by one of the partners, the Center for Snow and Avalanche Studies in Silverton.

This year, the researchers are driving the rover along 45 miles of U.S. 550 and periodically stopping to take readings at 10 sites. Next year, they’ll shift to pulling the rover behind a snowmobile in the backcountry on unpaved roads, which will eliminate the effects of pavement and snowbanks. The year after that, they’ll use the technology in southwest Colorado’s Dolores River watershed, part of the larger Colorado River Basin.

“This study will be the first to extensively test a Cosmic Ray Neutron rover for SWE estimation,” according to the Center for Snow and Avalanche Studies.

Using cosmic rays to measure the snowpack could occupy the space between two technologies that are currently employed: fixed SNOTEL stations that provide data on a single point, and flights by Airborne Snow Observatories, which can measure snow depth and SWE over a whole watershed. 

“This cosmic ray approach might be the middle guy where it’s not expensive, you can drive it at any time, you can get the data at any time,” said Jeff Derry, executive director of the Center for Snow and Avalanche Studies. “So if you had a wet spell or dry spell or whatever and you want to see changes over time, you can just go out and drive any old time you want.”

Next year, the rover will be towed behind a snowmobile on unpaved roads, eliminating the effects of the highway and snowbanks. 

Taking stock of the spring snowpack

By
Mitch Tobin
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State of the West’s snowpack on April 1, 2025. Source: Natural Resources Conservation Service.

April 1, the midpoint in the water year, is an important milestone for scientists, water managers, and others who track the American West’s snowpack.

Each watershed has its own typical peak date for the snowpack, but in many places, April 1 has been a traditional moment for taking stock of how the spring snowpack is stacking up.

Accordingly, I’ve collected a variety of maps and charts below that illustrate the state of play on April 1.

Snowmelt accounts for the majority of the flow in many Western rivers, so the current status of the snowpack has major implications for the runoff that will supply downstream ecosystems, agriculture, and communities.

That said, the weather over the next couple of months will play a crucial role in the story of this year’s snowpack. There’s still plenty of time for more flakes to fall in the high country—snow is in the forecast for the next few days—while warm, sunny, and dry conditions could accelerate the meltout.

The map I shared at the top of this post shows a summary of conditions across the West, and it paints a variegated portrait. All of those green areas are close to the 30-year median, but there are also basins with less than 50% of normal (red) or more than 150% of the median (deep blue).

Last year around this time, I did a similar update on the April 1 snowpack and included the graphic below, showing conditions for the last three seasons:

Source: my compilation of April 1 maps from the Natural Resources Conservation Service.

The map below shows precipitation since October 1. As with the snowpack, the Southwest has suffered while portions of Northern California, Oregon, Nevada, and Montana have done well.

Source: Natural Resources Conservation Service.

Overall, this season’s precipitation patterns “bore the telltale signs of a La Niña influence,” according to a recent post on NOAA’s ENSO blog:

“In particular, most of the southern U.S. and northern Mexico were predicted to be and turned out to be drier than average, with record-dry conditions in southern Arizona and parts of New Mexico. Wetter conditions were forecasted and did prevail over the northern part of the continent, particularly in Alaska and parts of the Pacific Northwest, as well as much farther south in Central America.”

Drilling down to the level of individual states, I looked through a slew of graphics and found a lot of places around average and not worth writing about. But below are a few different types of visualizations from the Natural Resources Conservation Service that caught my eye.

After a dreadful season, March storms were a blessing in Arizona, causing the black line in the chart below to spike upward, but the statewide snowpack was just 44% of the median (green line) on April 1.

Source: Natural Resources Conservation Service.

Shifting from snowpack to overall precipitation, Arizona was at the 5th percentile on April 1 with just 54% of the long-term median.

Source: Natural Resources Conservation Service.

In New Mexico, the meltout is underway after a dismal winter, with the statewide snowpack on April 1 at just the 5th percentile and 49% of the median.

Source: Natural Resources Conservation Service.

The chart below, which visualizes the snowpack’s growth by month, shows that 2025 is New Mexico’s worst year for snow since 2018.

Source: Natural Resources Conservation Service.

In Colorado, which supplies water to 19 states downstream, conditions in the northern portion of the state are near normal, but in the south, it’s a different story: the Arkansas, Upper Rio Grande, Gunnison, San Miguel, Dolores, and San Juan basins are all struggling.

Source: Natural Resources Conservation Service.

The skimpy snowpack in southern Colorado has pulled the statewide snowpack into below-normal territory. In the chart below, the dotted lines indicate possible trajectories for the rest of the season—a reminder that spring weather remains a wildcard.

Source: Natural Resources Conservation Service.

In California, where the state runs its own system for tracking the snowpack, conditions are close to normal, but there’s still the same north-to-south gradient that we’ve seen all season. The statewide snowpack was at 96% of normal on April 1, but the northern region was at 118%, and the southern region was at 83%. This is the third year in a row with near- to above-average snowpack in California—something that hasn’t happened in 25 years.

Source: California Department of Water Resources.

If you’re curious about where there’s still snow on the ground, the two maps below from the University of Arizona’s SnowView interactive show the estimated snow water equivalent across the country and around the West.

Source: SnowView.

The map below displays snowfall accumulation since the start of the water year on October 1. What stood out for me was the unusual swath of snow that fell across the Southeast in January, including a major winter storm in New Orleans.

Snowfall accumulation so far during the 2024-2025 water year. Source: Pivotal Weather.

The map for the U.S. Drought Monitor shows that dry conditions prevail over a large portion of the lower 48 states, with some areas in the West now recording “extreme” and “exceptional” drought.

Source: U.S. Drought Monitor.

The graphic below shows how the U.S. Drought Monitor has changed over the past six months. All that yellow, orange, and brown in the Southwest indicates that conditions have degraded so far this water year.

Source: U.S. Drought Monitor.

Looking ahead, the Climate Prediction Center says the odds are titled toward drier weather across much of the West during the April-June timeframe.

Source: Climate Prediction Center.

Data centers a small, but growing factor in Arizona’s water budget

By
Brett Walton, Circle of Blue
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Buckeye, at the western edge of the Phoenix metro region, is the location of a new data center development. (Brett Walton/Circle of Blue)

BUCKEYE, Ariz. – It was supposed to be called Cipriani, a master planned community with more than 9,700 homes at the western fringe of this sprawling desert city in central Arizona.

Plans have changed. One regional growth industry – housing – is being supplanted by another – computing. Even as both carry questions about efficient use of water in one of the driest, fastest-growing areas of the country.

Last August, Cipriani Holdings sold the 2,069-acre land parcel west of the Buckeye Municipal Airport to Tract, a Denver-based data center developer. Instead of housing people, the Cipriani site, now part of the Buckeye Tech Corridor, will incorporate up to 20 million square feet of commercial space to house the cloud.

These are boom times in central Arizona for data centers, particularly in Maricopa County, which is one of the country’s largest data center markets. Factors in its favor, according to Alan Howard, an industry analyst at Omdia, a research firm, include relatively cheap land, tax incentives, low power rates, and proximity to the computing needs of the 5 million people in the Phoenix metro area.

Data centers house the servers and advanced graphics processors that are the foundation of the contemporary internet – and modern life in general. Their purposes range from the small-scale and mundane (storing your beach photos) to the hyperscale and potentially world-changing (training AI models). In aggregate, their power demands and water consumption for cooling have increased exponentially, prompting concerns about the sustainability of data center growth in the Southwest.

Despite the environmental anxieties, there is reason for optimism on water. New data centers are more efficient than older models. Some are using reclaimed water to reduce potable water demand. If the local climate is right, they can use ambient air to cool their servers. Companies like CyrusOne and Microsoft are pioneering cooling systems that consume little or no water in their direct operations, not counting water used to produce their electricity. Though there are tradeoffs involved with energy use, water consumption is increasingly becoming less an absolute constraint and more about the choices companies make.

“I’m far more concerned about energy than water,” said Glenn Williamson, CEO of the Canada Arizona Business Council and chairman of EPCOR Water, a private utility that operates in the state. “For water, we know what we need to do. We just need to pull the trigger.”

New ‘C’ in Arizona’s Economic Geography

The server fervor extends to the highest reaches of government. On January 21, just a day after his inauguration, President Donald Trump hosted a trio of tech industry executives at the White House. Larry Ellison of Oracle, Masayoshi Son of SoftBank, and Sam Altman of OpenAI stood at the president’s side while Trump announced private sector investment in AI infrastructure that could approach $500 billion. For this Stargate Project, he promised the construction of “colossal data centers” to keep America leading the AI race against China.

“I’m going to help a lot through emergency declarations because we have an emergency, we have to get this stuff built,” Trump said.

More and more of this data center “stuff” is being built in Arizona.

School kids learn Arizona’s economic geography via alphabetic repetition. Five C’s were dominant in the state’s early years: cattle, citrus, climate, copper, and cotton. As those industries decline in relative importance, it might soon be time to add a sixth C: computing. Metrics vary, but according to Howard at Omdia, the Arizona data center market is between the fourth and eighth largest in the country. All the big tech companies – Amazon, Google, Meta, and Microsoft – have a presence in the state, as do the less visible names Centersquare, CyrusOne, and QTS.

Arizona encourages the growth of data centers through a sales tax exemption that was approved in 2013. The Arizona Commerce Authority, the regulating agency, says that 64 data centers have received the exemption that covers purchases of hardware and software.

Growth has been accompanied by guardrails. Chandler was the first municipality in the state to regulate data centers. An ordinance adopted in 2022 established siting and noise-reduction requirements, but it did not mention water. The city regulates data center water use through a 2015 policy that limits these facilities to 115 gallons per day, per thousand square feet of space. For additional water needs, the company operating the data center must find an outside source.

Marana, a town 20 miles northwest of Tucson, adopted an ordinance in December that prohibits the water department from supplying data centers with potable water. Companies must find an alternative source and file an application with the town that estimates annual water consumption. No data centers are currently operating in the Marana service area, said Heidi Lasham, the town water director.

In Buckeye, Tract is laying the foundation for a development that could house 40 data centers occupying 20 million square feet at full buildout. Tract’s business model is not to build the data centers, but to acquire land and develop water, wastewater infrastructure, and energy access for the site so that tech companies have a turnkey option for quicker entry into the market.

Tract would not discuss its water plans for the Buckeye development. Graham Williams, chief investment officer, did provide a written statement when asked whether Tract would set water-use requirements for tenants.

“We secure enough water for our sites for a solution that optimizes energy and water use,” Williams wrote. “This is built into our approval process so that our end users are incentivized to maintain these standards since relevant stakeholders have signed off on them.”

In effect, Tract will attempt to balance energy and water demands, since low-water cooling often increases energy consumption.

Terry Lowe, Buckeye water manager, said Tract intends to drill wells on the site to self-supply with groundwater. In the future, he said, Tract will transfer the water system to the city when it no longer wants to be in charge of operating it. A city planning document restricts the site’s groundwater use to 2,000 acre-feet per year.

Tract’s forthcoming groundwater use highlights a loophole in Arizona water law. The state, in 2023, placed a moratorium on new housing developments outside Buckeye whose water source is local groundwater. Existing housing developments that pump groundwater must pay to recharge what they use. Neither provision applies to industrial developments like Tract’s data centers that are located in areas without a renewable surface water supply. This irritates the homebuilding lobby, which complains of unequal treatment.

Amber Walsh, an analyst with Bluefield Research, said that data center water use is a complex topic because of rapid technological change in the industry. Total water demands at present have accelerated, even as individual data centers become more efficient. When viewed nationally, all those drops, in effect, have turned into a flood.

At the state level, data centers are a modest water user, even if they can put pressure on individual utilities. Walsh’s research at Bluefield indicates that data center water consumption in Arizona in 2025 will be roughly 905 million gallons, or 2,777 acre-feet. In the Phoenix area, this is enough water for nearly 10,000 homes annually. It’s less than a tenth of one percent of the state’s annual water use.

Site-specific water data is hard to come by because companies guard the information. Still, researchers and analysts have put together national and regional estimates.

According to Lawrence Berkeley National Laboratory, data centers accounted for 4.4% of U.S. electricity use in 2023, up from 1.9% in 2018. All that power creates heat that needs to be removed. The trend toward hyperscale data centers – the largest of the large, those from the tech titans that are involved in AI computing – has had a similar inflationary effect on water use. Nationally, water consumed in data center operations grew from 21 billion liters in 2014 to 66 billion liters (53,500 acre-feet) in 2023. Indirect water use – the water consumed by the power plants that provide electricity to data centers – amounted to another 800 billion liters.

Sterling Park in Loudoun County, Virginia, is part of the state’s “Data Center Alley,” the country’s largest data center market. (J. Carl Ganter/Circle of Blue)

Water demands are not set in silicon and they involve tradeoffs. They depend on three main factors: type of cooling system, climate conditions, and operational practices. These vary based on location and data center. In favorable climates, using ambient air to cool the equipment results in no water use, but it does require more energy. Evaporative cooling, in which water is the medium for transferring heat, is less energy hungry but consumes more water. Older, water-intensive cooling system designs are being phased out in many places in favor of more efficiency. The Berkeley Lab report, however, notes that the growth of hyperscale data centers using liquid cooling could reverse the efficiency gains.

“Unlike energy, using water to cool a data center is a choice, not a requirement,” according to Alex Setmajer of Equinix, a data center operator. “While all data centers require energy, the decision to use water or not is a decision we make intentionally based on the local climate and long-term sustainability of available water sources.”

Water is becoming a hotter topic in the data center world, but it is still not the main driver for industry decisions, Walsh said. “It’s more or less they select the site that they want and then they’re like, ‘Okay, how can we make whatever water requirements work?’”

For desert areas like Maricopa County, water limits are being met with technological innovation. The eight facilities in the Chandler data center campus operated by CyrusOne do not use water for cooling, and they use a negligible amount overall, only 180,000 gallons a year for humidification. All of the company’s new data centers from 2024 onward will use zero-water cooling.

There are other examples. In December, Microsoft, a computing giant, announced a similar operational innovation for its data centers: a closed-loop cooling system that recycles water, effectively cutting water consumption to zero. The company said in a post on its website that it will pilot the technology in 2026 in data centers in Phoenix and Mount Pleasant, Wisconsin, as it works to make zero-water cooling the “primary cooling method across our owned portfolio.”

The shift to less water-intensive cooling is not without a penalty. The tradeoff is more energy use. Microsoft says this energy increase will be “nominal” due to more efficient cooling equipment. The company declined to respond to questions about how it would implement the new zero-water cooling system designs.

Shutting the Bedroom Door

For Buckeye officials, the Tract development is another step in its rapid demographic evolution. At the turn of this century, Buckeye was a quiet farm town of 8,000 people. Now, it holds almost 120,000. By the turn of the next century, city officials are planning for more than 1 million.

Every weekday morning Buckeye witnesses an exodus. Workers flow out, leaving for jobs elsewhere. City officials reckon that 90 percent of working residents leave town to earn a paycheck, many joining the Interstate 10 caravan east into Phoenix. Peak drive times can be 30 minutes longer than in the off hours.

In the evening, the flow reverses. This is the standard definition of a bedroom community: sleep there, work elsewhere. Eric Orsborn, the mayor, said he wants to change that pattern. Buckeye’s future is aimed at developing not only its residential plots but also its business sector.

The Tract development, though it will generate only a modest number of non-construction jobs, is part of this plan.

“If you’re going to build a city of let’s say 300,000 by 2040, we don’t want everybody leaving the city every day to go to work,” Orsborn said. “So it is one of our highest priorities is to attract those jobs out this way.”

This story was produced by Circle of Blue, in partnership with The Water Desk at the University of Colorado Boulder’s Center for Environmental Journalism.

Dwindling water supply, legal questions push Colorado River into ‘wildly uncharted territory’

By
Heather Sackett, Aspen Journalism
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Lake Powell at Wahweap Marina as seen in December 2021. Dwindling streamflows and falling reservoir levels have made it more likely that what some experts call a Colorado River Compact “tripwire” will be hit in 2027. (Heather Sackett/Aspen Journalism)

Time is ticking for states that share the shrinking Colorado River to negotiate a new set of governing rules. One major sticking point, which has the potential to thrust the parties into a protracted legal battle, hinges on differing interpretations of a few sentences in a century-old agreement. 

In a recent letter, the river’s Lower Basin states – California, Nevada and Arizona – asked federal officials to analyze the effects of a hypothetical legal concept known as a “compact call.” 

The problem? The 1922 Colorado River Compact says nothing about a compact call. And although the phrase often looms like a threat over Colorado River discussions, there is no agreed-upon definition of the term, what would trigger a compact call nor how one would play out. In fact, the Upper Basin states – Colorado, New Mexico, Utah and Wyoming – don’t believe the laws governing the river even contemplate it.

The February letter comes as water managers from all seven Colorado River Basin states are in the midst of deciding how Lake Powell and Lake Mead will be operated and cuts will be shared after 2026 when the current guidelines expire. In March 2024, each basin submitted competing proposals to the U.S. Bureau of Reclamation. In January, federal officials with the outgoing Biden administration released their analysis of five different potential ways forward and did not include either basin’s proposal, but a “basin hybrid” that incorporated elements from both. 

In essence, the Lower Basin states have identified a potential opening with the Trump administration, and asked new leaders at the Interior Department to adopt the Lower Basin’s view on some of the most contentious and disagreed-about parts of Colorado River management.

“I believe that under the law, the compact requires delivery of 7.5 million acre-feet of water on a 10-year rolling average, plus one-half of the Mexico Treaty obligation to the Lower Basin,” said Tom Buschatzke, director of Arizona’s Department of Water Resources. “So we want to see Reclamation, as our request indicated, incorporate that outcome into the modeling for any alternative to look at. That includes how reductions in the Upper Basin states might have to occur.”

Over a century ago, the compact split the river’s water evenly, with half (7.5 million acre-feet a year) going to the Upper Basin and half to the Lower Basin. Another 1.5 million acre-feet a year was later allocated to Mexico.  

The crux of the dispute comes from how the Upper Basin states and the Lower Basin states each interpret a key phrase in the compact: “The States of the Upper Division will not cause the flow of the river at Lee Ferry to be depleted below an aggregate of 75,000,000 acre-feet for any period of ten consecutive years…”

To the Upper Basin states, “will not cause” means that their use won’t be the reason the Lower Basin doesn’t get its allocation. They see it as a “non-depletion” obligation. 

According to Colorado officials, they’re not delivering water downstream, but rather  they’re not causing the flows to be depleted. 

“What this means is that if the flows were to drop below 75 million acre-feet over a ten-year period, there would be an inquiry into what caused that to occur,” Michael Elizabeth Sakas, Colorado River communications specialist with the Colorado Water Conservation Board said in a written response to questions from Aspen Journalism.  

On the other hand, the Lower Basin states say they’re owed the water, with the Upper Basin states required to send the 75 million acre-feet over 10 years, plus half of the Mexico Treaty obligation (which works out to 82.5 million acre-feet every 10 years) downstream to the Lower Basin. 

(Graphic credit: Laurine Lasalle/Aspen Journalism)

Compact “tripwire” threatens to complicate

Colorado River expert Eric Kuhn says that the latest report from the U.S. Bureau of Reclamation is a major caution sign for the basin. An anemic snowpack this past winter could be setting the basin on the road to a compact call (as defined by the Lower Basin). The most recent federal forecast predicts that in 2027, the 10-year cumulative flow at Lee Ferry could drop below 82.5 million acre-feet, a threshold Kuhn calls the first “tripwire” for a compact call. 

“If flows were to go below 82.5 million, then that’s the first time, in theory, the lower division states could point to the Upper Basin and say, ‘You’re not complying with your compact obligations,’” Kuhn said. “This is not going to sneak up on us. I think most of the modeling shows that it’s almost inevitable we will drop below 82.5 in the next three or four years.” 

But Upper Basin officials disagree. In their interpretation, this tripwire doesn’t exist. A compact call is a concept recognized only by the Lower Basin. 

They also point out that calls for water apply to situations where there is a senior rights holder and a junior rights holder. Under the prior appropriation system, the oldest water rights get first use of the river, and senior rights can force junior rights to stop using water so seniors can get the full amount they are entitled to. But Upper Basin officials say there is no priority between the two basins; they are on equal standing.

That may be true, but the three Lower Basin states are also home to the basin’s biggest water users and cities, with more political power than the sparsely populated Upper Basin states.

Navajo Bridge spans the Colorado River downstream from Lake Powell near Lee Ferry, the dividing line between the upper and lower basin. Some federal forecasts predict that in 2027, the flow at Lee Ferry could drop below a critical threshold that some experts call a “compact tripwire.” (Heather Sackett/Aspen Journalism)

River headed for “wildly uncharted territory”

So what would happen if and when the river shrinks enough to trigger the first compact tripwire?

In practice, a compact call could mean the Lower Basin states would sue the federal government to get them to send more water downstream from Lake Powell. (The U.S. Bureau of Reclamation is responsible for making releases from Lake Powell and Lake Mead.) The Lower Basin states could also demand that the Upper Basin states implement cuts to get more water into Lake Powell. But the Upper Basin states will almost certainly argue they are in compliance with the compact and don’t need to make cuts. The Supreme Court could then decide whether the Upper Basin states are in compliance with the compact.

“It’s wildly uncharted territory,” said Chuck Cullom, the executive director of the Upper Colorado River Commision. “It’s not a straightforward path to say: ‘We need you to release more water out of Glen Canyon Dam and curtail uses.’”

The Upper Basin’s argument hinges on what is causing the flows at Lee Ferry to drop. The four states say it’s not their fault, because they only use between 3.5 and 4.5 million acre-feet a year, far less than their allocation of 7.5 million acre-feet. The culprit, they say, is climate change, which according to scientists has contributed to a 20% decline in flows from the 20th century average. They have also shown that every 1 degree Celsius of warming results in a 9% reduction in flows. 

With a fixed number for how the river is shared, and a slowly dwindling amount of water available, the Upper Basin has been bearing the brunt of the effects of climate change, a phenomenon that Kuhn calls the “Upper Basin squeeze.” But the climate change argument could open a can of worms.

“There are numerous other water compacts between states,” Kuhn said. “Are we reopening every one of those? It could mean that other states do not have to comply with their compact obligations.That would be a precedent decision that would affect every compact in the western United States.”

How would cuts work?

Water users on Colorado’s Western Slope are eager to know how cuts could play out and over the past few years they have asked state officials repeatedly for more clarity on this issue. One reason is because most of the big transmountain diversions that take water from the mountainous headwaters of the Colorado to Front Range cities date to after the 1922 compact, meaning they would likely be cut first. But as the population centers and economic engines of the state, it’s unlikely a plan to cut water use would include turning off the taps to Denver.  

In a crisis situation where cuts are mandatory, the strict prior appropriation system would probably not hold.

“They’re going to have to make hard decisions, and they are going to primarily meet the human health and safety needs of people first,” Kuhn said. “It’s an open secret that the priority system works under normal conditions; it doesn’t work in emergencies.”

Western Slope water users also want to know the state’s plan for cuts, because some areas may be more at risk of forced cutbacks than others. The Yampa/White/Green River basin in the northwest corner of the state, for example, developed later than other places, with lots of more junior water rights. Would they be first on the chopping block? 

“We believe that regardless of where things stand on the river, clarity can’t hurt water users,” said Peter Fleming, general counsel with the Colorado River Water Conservation District. “In the long run, clarity will help people to plan better.”

But state officials have been reluctant to provide clarity about how cuts could be implemented, saying now is not the time to plan for it and that the Upper Basin states have always been in compliance with the compact.

“Colorado is not at risk of any compact curtailment scenario in the near future,” Sakas said in a written response to Aspen Journalism. “For the last 20 years, the Upper Basin has been using half of what we are allowed to use under the 1922 Compact while our downstream neighbors use significantly more than their apportionment.”

Figuring out who would be the first to take cuts and tracking that water to the state line would not be an easy task, said Colorado River expert Jennifer Gimbel. Gimbel is the senior water policy scholar at the Colorado State University Water Center and is the former director of the Colorado Water Conservation Board. 

“It would be a tremendous headache and a huge undertaking,” she said. “But I don’t know if that means we shouldn’t be doing it.”

The Colorado Division of Water Resources, in a first step, has been developing measurement rules and requiring measurement devices for water users across the Western Slope. According to state officials, the goal of this effort is to accurately measure diversions so that if necessary, Colorado sends downstream only the water that is required to maintain compact compliance and not a drop more. 

Trying to stay out of court

One thing most water managers agree on is that finding a seven-state consensus is better than the potentially protracted litigation possible under some kind of compact call scenario. Some are hoping for the best but preparing for the worst. The Arizona Department of Water Resources requested about $1 million last year for Colorado River litigation from the state budget. Buschatzke said the Upper Basin states might fare worse under a compact call than they would by adopting the Lower Basin proposal.

“Because there are a lot of moving parts, litigation — a compact call — is a possibility,” he said. “It’s not a possibility I want to see occur. But I’ll have to do what I have to do to protect the state of Arizona.”

If the states can come up with new guidelines that fairly share the river, the threat of a compact call, which has long hung over Colorado River management discussions, could evaporate like water from the surface of Lake Mead. Cullom said that in 2007 when the seven states implemented the soon-to-expire guidelines that are currently in place, they agreed that if the two basins made good on their commitments outlined in those guidelines, they would set aside the issue of compact compliance — at least until after 2026.

“If they can figure out a way to live within the means of the river in such a manner that both the Upper Basin and Lower Basin agree, hopefully addressing a compact call again won’t be needed because it’s been addressed,” Gimbel said. 

This story was produced by Aspen Journalism, in partnership with The Water Desk at the University of Colorado’s Center for Environmental Journalism. 

9 graphics that visualize EPA’s climate change indicators for snow

By
Mitch Tobin
-
Teton Range and Snake River near Jackson, Wyoming, in March 2018. Photo by Mitch Tobin.

I can’t vouch for its shelf life in the Trump administration, but the U.S. Environmental Protection Agency continues to publish a revealing set of indicators of climate change impacts, including 14 connected to snow and ice. 

These data sets, many of them visualized with simple maps and time-series charts, show the unmistakable effects of warming and cover a wide range of subjects, including public health, ecosystems and oceans. 

Below I share and describe nine graphics that focus on snowfall, snow cover and the American West’s snowpack. All of these measures document concerning trends about this corner of the cryosphere—the frozen portion of the Earth’s surface.

The downward trajectory for snow carries serious consequences, including reduced water supplies, increased wildfire activity, imperilment of species and harm to outdoor recreation.

I’ve been meaning to write about these indicators for a while, but the task took on added urgency when I started to read about scientists and others scrambling to download data and other resources from federal websites before the information was removed by the Trump administration (see stories here and here for more). 

On February 26, Trump said during a cabinet meeting that he planned to slash EPA’s staff by 65%, with aides later clarifying that this number referred to budget cuts. 

Curious about whether these indicators will continue to be published, let alone updated, I emailed EPA’s press office, but the agency declined to comment for this story.

These climate change indicators have gone through layers of scientific peer review and involve partnerships with more than 50 data contributors, including government agencies, academic institutions and other organizations (see this FAQ on the EPA website for more). I’ve listed sources at the bottom of the post.

“EPA’s indicators are designed to help readers understand observed long-term trends related to the causes and effects of climate change. In other words, they provide important evidence of ‘what climate change looks like,’” EPA says. “Together, these indicators present compelling evidence that climate change is happening now in the United States and globally.”

Snowfall

This indicator looks at snow in the contiguous 48 states using two measures: the total amount of snowfall and the fraction of precipitation that falls as snow rather than rain. 

EPA notes the many ways in which snowfall is critical, both economically and ecologically: snowmelt provides the bulk of the water supply in many Western communities, snowfall underlies winter recreation activities and snow keeps some species alive. Snowfall is the major driver of the two indicators discussed below: snow cover and the snowpack. 

Overall, warming leads to increased evaporation of moisture into the sky and more resulting precipitation, but higher temperatures are causing more of this precipitation to fall as rain, rather than as snow. “Some places, however, could see more snowfall if temperatures rise but still remain below the freezing point, or if storm tracks change,” according to EPA. “Areas near large lakes might also experience more snowfall as lakes remain unfrozen for longer periods, allowing more water to evaporate. In contrast, other areas might experience less snowfall as a result of wintertime droughts.”

As shown in the map below, snowfall from October to May decreased in many parts of the contiguous 48 states from 1930 to 2007, with 57% of stations declining. More than 400 stations are included in the data set, and their average change was a decrease of 0.19% per year. EPA says the stations were selected for their high-quality, long-term data, but it’s not clear why the data ends in 2007; it would be interesting to see updated figures.

The graphic below shows a pronounced shift in the rain/snow mix for precipitation: more than 80% of the stations saw a decrease in the percentage of precipitation falling as snow from 1949 to 2024. This data set runs from November through March, but in some regions, that time period doesn’t capture the entire snow season.

EPA highlights some regional differences in the snowfall trends. In the Pacific Northwest, there has been a decline in both total snowfall and the fraction of precipitation falling as snow. Some areas in the Midwest have seen a decrease primarily due to changes in the snow-to-precipitation ratio, but other locations, such as those near the Great Lakes, have received more snow than in the past. 

The process of measuring snow depth is familiar to anyone who has used a yardstick in their backyard, but EPA notes that precisely measuring snowfall is challenging because it’s subject to human error, and snowfall can vary dramatically across short distances due to wind, trees and other factors. Snow gauges may catch less snow than rain because of the wind, and many of the stations in mountainous regions are in lower-elevation valley towns that may not reflect conditions higher up.   

Snow cover

One important measure of snow’s prevalence is the amount of land it covers. With this indicator, the depth or water content of the snow doesn’t matter: this metric only concerns whether there is snow or not. Thanks to satellite imagery, scientists can look back many decades to study trends in snow cover; in this case, the time series extends back to 1972.

Changes in both precipitation and temperature affect snow cover. Dry times mean less snow on the ground, but even with normal precipitation levels, the snow cover may be reduced if it’s too warm to snow, causing rain to fall instead. 

Climate change is influencing snow cover around the world, and the reverse is also true: the fraction of land covered by snow affects the Earth’s climate because snow is so much more reflective than bare ground or open water. Snow’s high “albedo” means that it exerts a cooling effect, but if snow cover is reduced, the planet’s surface absorbs more energy from the sun.

“On a more local scale, snow cover is important for many plants and animals. For example, some plants and animals rely on a protective blanket of snow to insulate them from sub-freezing winter temperatures,” according to EPA. “Snow cover also keeps the soil moist, so if the snow melts away earlier in the spring, the soil may dry out sooner, which can stress plants and increase the risk of wildfire.”

The chart below shows the average area in North America (minus Greenland) that was covered by snow each year, based on an analysis of weekly maps. 

Although the line in the graphic above looks flat, snow cover decreased slightly at a rate of about 2,083 square miles per year. 

In the most recent decade (2014-2023), the annual average area covered by snow was 3.25 million square miles, which was about 3% less than during the first 10 years of the time series (1972-1981). That’s nearly 93,000 square miles less, or an area slightly smaller than Michigan, according to EPA. 

The graphic below shows how snow cover has changed during each of the four seasons. “Decreases in snow cover have largely occurred in spring and summer, whereas winter snow cover has remained fairly steady over the time period studied and fall snow cover has increased,” according to EPA. “Spring and summer snow cover can have a particularly important influence on water supplies.”

EPA’s final indicator for snow cover concerns the length of the season, as shown in the chart below. This measure ends in 2013 and only covers the contiguous 48 states and Alaska, rather than all of North America. 

“Between 1972 and 2013, the U.S. snow cover season became shorter by nearly two weeks, on average,” EPA says. “By far the largest change has taken place in the spring, with the last day of snow shifting earlier by 19 days since 1972. In contrast, the first date of snow cover in the fall has remained relatively unchanged.”

Snowpack

The snowpack—the seasonal accumulation of snowfall—plays a critical role in the West’s water supply and ecosystems. The annual melting of the West’s snowpack fills rivers, reservoirs and irrigation canals, providing vital water to crops, residents and wildlife while also generating hydropower at dams. “In most western river basins, snowpack is a larger component of water storage than human-constructed reservoirs,” EPA notes. 

This indicator is based on snow water equivalent (SWE), the key measure of the snowpack’s water content. The SWE at a location is equivalent to the depth of water you’d get by melting a column of snow.

Some trees rely on the snowpack for insulation from freezing temperatures, and EPA says that “fish spawning could be disrupted if changes in snowpack or snowmelt alter the timing and abundance of streamflows” (see EPA’s streamflow indicator for more on this issue). A diminished snowpack can also “accelerate the start of the wildfire season and promote more wildfire activity in the western United States and Alaska,” according to EPA. 

The map below shows trends in the American West’s snowpack from 1955 to 2023: red circles indicate declines, blue circles show increases and the circles are sized according to the magnitude of the change. Overall, April SWE declined at 81% of the sites, with an average decrease of about 18%. “Large and consistent decreases in April snowpack have been observed throughout the western United States,” according to EPA. “Decreases have been especially prominent in Washington, Oregon, northern California, and the northern Rockies.” 

Although SWE increased at some stations, the overall trend was downward in all 12 states included in the indicator. In the Pacific Northwest region (Idaho, Oregon and Washington), all but four stations saw decreases in the snowpack. 

The map above is based on nearly 700 measuring sites, but the graphics below are based on a smaller subset of 340 stations that have daily data stretching back to 1982.  

One metric examines changes in the timing of the West’s peak snowpack from 1982 to 2023, as shown in the map below. Red triangles indicate earlier peaks, blue triangles show later peaks and the triangles are sized according to the size of the change. 

“Almost 80 percent of sites have experienced a shift toward earlier peak snowpack,” according to EPA. “This earlier trend is especially pronounced in southwestern states like Colorado, New Mexico, and Utah.”

EPA also reports the date at which the West’s snowpack peaked from 1982 to 2023, as illustrated in the chart below. There is considerable year-to-year variability in this measure, but based on the long-term average rate of change, peak snowpack has come earlier by an average of nearly seven days since 1982.

Finally, EPA reports how the snowpack season’s length has changed from 1982 to 2023, as shown in the map below. At about 80% of the sites, the snowpack season decreased (red circles), with an average decline of about 15 days. 

Data sources and studies

Snowfall 

Snow cover  

Snowpack

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