Elephant Butte Reservoir, along the Rio Grande near Truth or Consequences, N.M., in August 2022. (Mitch Tobin/The Water Desk)
This program is no longer open to applications.
The Water Desk is excited to announce an in-person training and workshop for journalists interested in covering the Rio Grande watershed to be held in El Paso, Texas.
The Rio Grande faces significant challenges: climate change, aridification, pollution, development, population growth, invasive species and more. The river forms a portion of the U.S.-Mexico border and is a critical water supply for three U.S. states—Colorado, New Mexico and Texas. As supplies shrink and tensions ramp up, litigation among the river’s users continues to make headlines. Tense diplomatic relations between the U.S. and Mexico are affecting the Rio Grande as well.
To equip journalists to better understand the river’s current and future challenges, The Water Desk will host a training program for journalists in El Paso, Texas, on March 25-27, 2026. Participating journalists will hear from legal experts, tribal leaders, environmental advocates and other speakers who can shed light on the Rio Grande.
We will select up to 15 participants who represent diversity in geography, race, gender and journalistic medium. Travel, lodging, meals and other expenses will be covered for all attendees. Additional funding for story coverage after the training will be made available. The program will begin the evening of March 25 and conclude in the afternoon on March 27.
The Thornburg Foundation, a Santa Fe-based family foundation, is providing the financial support to make this training possible, while the program’s content is the sole responsibility of The Water Desk. Deadline for applications is Monday, January 12, 2026 at 11:59 pm Mountain.
Testimonials from journalist-participants at our 2025 Rio Grande workshop, held in Albuquerque, New Mexico:
“The most valuable part of the workshop was the boost of inspiration and support I got from spending 2.5 days with other passionate journalists and advocates.”
“I loved the collaboration opportunities, I loved the speakers, I loved the venue, I loved the opportunity. The whole thing was the best part of my journalistic year and was truly the jump start I needed.”
“I came for the information, but found that in the end the most valuable part of the workshop were the new relationships with fellow journalists I came away with.”
A welcome sign in Price reminds residents to save water, Sept. 30, 2025. Consistent messaging is likely one of the reasons Carbon County has become a leading county for conservation in Utah. (David Condos/KUER)
Water Desk Grantee Publication
This story was supported by the Water Desk’s grants program.
One size fits all. That’s great for hats in the Zion National Park gift shop but not for water conservation goals.
So at the start of this decade — and for the first time — Utah figured it would ditch that statewide approach and set goals that account for regional differences in water supplies and uses.
After all, life in Salt Lake County isn’t like living in the eastern rural counties along the Colorado border. Water, as it turns out, “is very hyperlocal,” said Candice Hasenyager, director of the Utah Division of Water Resources.
To meet a statewide conservation goal of 16%, the decade-long effort aims to reduce the water used in homes, schools and businesses. Individual targets were set for each county to make it happen. Farm irrigation isn’t part of it — there are other ways to save water there. While it’s true that most of Utah’s water goes to agriculture, “ag is not always where the people are,” Hasenyager said. So, how Utahns conserve in cities and towns still matters.
Halfway through the initiative, however, the results are mixed.
“There are some areas that have already exceeded the goals, which is great,” Hasenyager said. “Then there are other areas that we know need to do a lot more work.”
Fifteen of Utah’s 29 counties have reached their annual 2030 goals at least once in the past two years. That list of success stories ranges from the most populated county, Salt Lake, to the least, Daggett. Washington, Iron and Tooele counties hit their targets in at least one recent year, too. But 14 other counties have not, including Weber, Juab and Box Elder.
Four rural counties in Utah’s Colorado River Basin — Carbon, Duchesne, Uintah and Wayne — are a microcosm of the state’s successes and struggles.
Take Carbon County and its goal is to use an average of 239 gallons per person per day by 2030. That would be an 11% decrease from the 267 gallons it used in 2015, the state’s baseline year for the reduction targets.
In 2024, the county used 197 gallons per person per day, the fifth lowest rate in the state. That’s even less per capita than urban Salt Lake and Utah counties. So, they beat their goal last year.
Uintah met its goal in 2023, years ahead of the deadline.
It’s a different story for Duchesne and Wayne. Both are using more water than they did a decade ago.
Talking about saving water matters
Seemingly similar counties — like, say, Duchesne and Uintah or Salt Lake and Weber — have seen very different outcomes. The reasons behind such disparities range from money to lot sizes to local economies.
It also comes down to the priorities of local leaders and how they talk about saving water. Ultimately, that trickles down to influence people’s behavior.
“People need to be convinced there’s a need and a purpose for undertaking water conservation activities,” said Joanna Endter-Wada, a Utah State University water policy and sociology of conservation researcher.
It can take time — years — for the message to sink in and shift a community’s culture. So, how long and how vigorously a county has emphasized conservation can make a difference.
Wayne County uses more water per person than any other part of Utah, in excess of 900 gallons per capita per day.
That doesn’t surprise Mickey Wright, a retired software engineer who’s the mayor of Torrey. It’s a town of 332 people near Capitol Reef National Park.
“I think our focus hasn’t been enough on water,” Wright said. To him, the biggest barrier to conservation is shifting from an individualistic to collective mindset.
“We don’t think of ourselves as being that significant, that my little bit doesn’t have that much effect.”
Mayor Mickey Wright walks across a patch of grass near Torrey’s city office, Sept. 29, 2025. The town plans to replace the grass with desert landscaping next year to start setting a better example with water conservation. (David Condos)
Wright grew up in rural southern Colorado and remembers a life of water rationing. When he first came to Utah to meet his wife’s family, he was struck by all the green lawns.
Now, he wants Torrey to start setting a better example.
Outside the old fire station repurposed as the city office, Wright walked across a patch of grass whose days are numbered. By next spring, he said it’ll become a high desert garden with native grasses and flowers. The idea is to inspire residents and businesses to do something similar.
Wright remains hopeful Wayne County can turn things around and hit its goal in the next five years, but he acknowledges change can be difficult. When he pitched a grass removal rebate program earlier in his term, he had a hard time getting support.
But the alternative to conservation is expensive. Torrey will need more water as it grows, the mayor said, which would require pipeline projects to bring it in that could easily top $5 million.
“The less water we use, the less millions we’ve got to go find,” Wright said. “That’s the argument I’ve got to make.”
People are trying to start a similar conversation to the north of Wayne in Duchesne County. It uses the sixth most water per capita in Utah and would need to cut back by more than 40% to reach its 2030 goal.
They’re part of the Central Utah Water Conservancy District, which stretches from Orem to the Colorado border. That’s a lot of ground to cover, so Savannah Peterson, one of the district’s water conservation programs coordinators, knows she needs to speak everyone’s language.
“Using words like ‘xeriscaping’ or ‘waterwise’ in more urban areas is a really popular thing. But in our rural areas, we talk about ‘drought resiliency,’” Peterson said. “We’re trying to meet people where they are in terms of their understanding of the water situation.”
Savannah Peterson of the Central Utah Water Conservancy District checks on flowers growing in a waterwise garden outside the district’s office in Duchesne, Oct. 3, 2025. (David Condos)
The district already offers rebates to help Duchesne residents replace leaky toilets, upgrade sprinkler controls or remove thirsty lawns. But folks often think of those programs as a city thing, and they may not even realize it’s available to them.
“Water districts have sometimes been seen as the bad guy,” she said. “But we want to make sure that people know we’re a resource.”
Over the past decade, his team has worked to dispel common myths, like the thought that conserving locally means sending more water downstream to California. The reality, he said, is that saving water stores it in Uintah’s reservoirs.
As drought set in this spring, his district raised its rates and told customers why.
“People don’t like being told what to do, and so my message to that is: We don’t tell them what to do. We explain the situation and let them pick,” Goodrich said.
That meant choosing between paying a higher bill or trying to cut back, he said, “but if they don’t understand the underlying reason for it, they’re not going to do it.”
Uintah’s local efforts appear to be paying off. It hit the state’s 2030 goal in 2023 with 209 gallons per capita per day, before slipping back above the target line in 2024.
The district already offers rebates to help Duchesne residents replace leaky toilets, upgrade sprinkler controls or remove thirsty lawns. But folks often think of those programs as a city thing, and they may not even realize it’s available to them.
“Water districts have sometimes been seen as the bad guy,” she said. “But we want to make sure that people know we’re a resource.”
Over the past decade, his team has worked to dispel common myths, like the thought that conserving locally means sending more water downstream to California. The reality, he said, is that saving water stores it in Uintah’s reservoirs.
As drought set in this spring, his district raised its rates and told customers why.
“People don’t like being told what to do, and so my message to that is: We don’t tell them what to do. We explain the situation and let them pick,” Goodrich said.
That meant choosing between paying a higher bill or trying to cut back, he said, “but if they don’t understand the underlying reason for it, they’re not going to do it.”
Uintah’s local efforts appear to be paying off. It hit the state’s 2030 goal in 2023 with 209 gallons per capita per day, before slipping back above the target line in 2024.
Between the higher water rates and a new outreach plan of radio ads, text messages and flyers, Goodrich said his district has cut water use by roughly another 20% this year.
It’s great to see how far Uintah has come with conservation, Goodrich said, but it’s no time to rest on their laurels.
“We are doing a pretty good job. We can do better,” he said. “This year was the year that we said we have to do better, because we just don’t have the water.”
Ryan Goodrich of the Ashley Valley water district stands next to Ashley Creek, Oct. 2, 2025. This tributary of the Green River provides water for communities around Vernal, but it has run low this year because of drought. (David Condos)
The size of a community’s wallet matters, too
Clear, consistent communication isn’t the only thing that can help residents save more water. Small towns may have just one person managing their water system, Endter-Wada said, while bigger cities have a whole staff of water conservation experts.
The more resources a community has, the more likely they’ll be able to implement conservation efforts such as lawn replacement incentives and hiring employees to manage those programs.
“At the end of the day,” Hasenyager, the state water director, said, “conservation costs money.”
There are real barriers in places with fewer people and smaller budgets. That’s the case in Myton, a town of 662 in Duchesne County.
Water is so vital to life in this part of northeast Utah that Myton showcases a ragged wooden pipeline from the early 20th century in its museum. But even the pipes that carry Myton’s water into town today have problems. Many are nearing 50 years old and leak badly, Mayor Kathleen Cooper said. Those pipes routinely lost more than a fifth of the town’s water over the past decade.
But Myton doesn’t have the money to replace them.
“I don’t know who you blame,” Cooper said. “All I know is that I need water pipes, and we only have 600 people.”
Myton Mayor Kathleen Cooper stands next to an old water pipeline in the town’s historical museum, Oct. 1, 2025. She says many of the town’s current pipes leak badly, but Myton doesn’t have the money to replace them. (David Condos)
Around a quarter of the town’s residents live below the poverty line. That’s more than triple the state average. It also overlaps with Ute tribal land and around one-sixth of its residents are Native.
“We don’t have a bunch of oil barons living in Myton that could raise our property rates so that we would get more money,” Cooper said. “So, we have to rely heavily on grants.”
And those federal funds dwindle by the second, she said.
On top of that, small towns face a competitive disadvantage. If they apply for grants, Endter-Wada said, they’re often up against urban and suburban communities that hire outside consultants to juice up their proposals.
When rural areas do get their hands on the money, it’s easy to see the impact. Look at the town of Helper, in Carbon County, just south of Duchesne.
Along a highway in Price Canyon, Mayor Lenise Peterman rested her hand on a rusted pile of scrap from a pipeline that brought water to town for 70 years. Before they replaced it, the town of 2,680 people lost about half its water before it ever made it to someone’s kitchen sink.
Helper made it happen thanks to $3.4 million in federal post-pandemic funds. That’s nearly double the town’s entire annual budget, Peterman said.
“We were fortunate to get that funding and to make it happen,” she said.
“We knew we weren’t doing that well,” the mayor added. “It wasn’t that we weren’t trying, it was that the infrastructure was failing us.”
With the new pipe installed, Helper can focus on next steps for saving more water. For example, the mayor wants to start a program in the local schools to teach kids about conservation.
The project to replace Helper’s leaky water pipeline cost more than twice the town’s annual budget, said Mayor Lenise Peterman, seen here at the project site Oct. 1, 2025. The water-saving project might not have happened without millions in federal funds. (David Condos)
The nearby town of Price also has a leaky pipeline that’s nearly a century old. City council member Terry Willis said they recently snagged around $5 million in grants and $10 million in loans to replace it.
“When you have to say millions, it makes your heart beat a little bit and makes your stomach churn a little bit,” Willis said. “But it’s the reality of what it is.”
Price and Helper are both in Carbon County, which has already met its 2030 goal.
Between hotter, drier weather and concerns about the future of the Colorado River, there’s urgency for communities to keep going.
“We watch the climate change, and it has continued to change since I’ve lived here,” Willis said as she stood next to the Price River, which can dry up during drought. So, conservation has to be at “the forefront of everything we do. Because without water, the community will fail.”
Mayor Cooper said Myton has applied for federal and state checks, too. In the past couple of years, the town has gotten outside funds to replace water meters and launch an app for residents to check their water use.
She wants to do more, though. And hasn’t given up yet.
“I’m always hopeful,” Cooper said with a laugh. “You have to be in Myton. That’s all we have left is hope.”
Price city council member Terry Willis stands next to the Price River, Sept. 30, 2025. The river provides water for the city’s supply, but parts of it can dry up during drought years. (David Condos)
When water props up rural economies and larger homes
In 2023, homes were the top water users in Uintah and Carbon counties’ municipal districts. Most commercial, institutional and industrial customers didn’t come close.
Residential was also the leading user in every Wayne County district except one. That was in Torrey, Capitol Reef National Park’s gateway town, where the commercial sector used the most.
That likely points to one influencing factor: tourism. People staying at hotels, resorts and RV parks may use Torrey’s water, but they aren’t counted in its population.
Visitors spent $54.8 million in Wayne County in 2023, according to data from the Kem C. Gardner Policy Institute. That means tourism brought in $21,720 per resident — significantly higher than tourism’s relative impact in Duchesne ($2,581 per resident), Carbon ($4,309) or Uintah ($6,253).
Wayne has a small population, 2,543, and visitors could have an outsized impact on its per capita numbers. Still, a small number of residents hasn’t stopped neighboring Garfield County — home to 5,115 people and Bryce Canyon National Park — from decreasing its water use since 2015, while Wayne’s has gone up.
Duchesne may not have as much tourism, but it ranks high for fossil fuel extraction. In a 2021 letter to President Joe Biden, local leaders described the county as Utah’s top crude oil producer and No. 3 for natural gas.
In Duchesne’s Johnson Water Improvement District, industrial customers used 689,441,942 gallons 2023. That’s more than five times what the district’s residents used that year and nearly twice as much as all the homes in Roosevelt, the county’s largest city. On its website, the district says it provides a “substantial amount of water” to the oil and gas industry.
Other industrial uses, such as data centers and processing plants, can have similar impacts on water in rural areas, Endter-Wada said.
“So, it’s really not just a reflection on the individual behaviors of the residents in the area, but it reflects the economy as a whole,” she said.
When water props up the local economy, it is hard to cut back. That illustrates why it’s important to be cautious about the types of new industries Utah leaders welcome, Hasenyager said.
Large rural lot sizes also skew the data, Endter-Wada said, because more than half of Utah’s residential water gets sprayed onto lawns and gardens. If you have a family of five living on a small tract in the city, they’re likely to use less water than a family of five on a sprawling property in the country.
“Distribute that water use over a smaller population,” Endter-Wada said and “you’ll see greater gallons per capita per day numbers.”
Wayne has the largest average lot size in Utah, more than triple Salt Lake County’s, according to state data. Duchesne’s lot sizes are in the middle of the pack — similar to the average in Utah County and smaller than Uintah’s.
Another factor is that the state has to estimate much of Wayne’s water use, Hasenyager said, because there aren’t enough meters tracking the actual gallons. Installing measuring devices for all of Utah’s secondary water systems, which generally go to landscaping, is another state goal for 2030.
Until then, there may be some farm irrigation inadvertently counted with the county’s city water.
“I’m pretty convinced that [Wayne’s data] has agricultural water in it, and we need to try to dig into that,” Hasenyager said
The state is also digging into potential changes to the 2030 goals.
Right now, the target reductions are based on each county’s average water use from 2015. The state may soon use the average from 2015 to 2019 as the baseline instead. That change would bring Wayne and Duchesne closer to hitting the mark, but their 2024 water use would still be significantly higher than those updated goals.
Utah may also start using a percentage to reflect how close each county is to its goal, Hasenyager said, rather than the specific amount of water it uses.
Other changes have already happened. In 2025, the Legislature directed Utah’s five most populous counties to report their consumptive water use, rather than total water use. That allows a county to subtract return flows — the gallons that go back into the water system — from its sum and results in a lower per capita figure. This story relies on the total water use for those five counties rather than consumptive use to maintain a direct comparison with the counties’ data from 2015-2019 and with the data from the other 24 counties.
Despite around half the state’s counties falling short of their 2030 goals so far, Hasenyager said Utah is in a much better place than it was five years ago.
“There are more programs now than ever before that are encouraging water conservation from all different levels — from the state, from the districts, from the local water suppliers,” she said. “So, I’m really hopeful and confident that more of our counties will meet those 2030 goals.”
There’s no penalty for those who don’t meet their goals by the end of the decade. But communities who aren’t careful with their water, Hasenyager said, could face natural consequences in such a dry state.
Listen to this series by David Condos
Part 1
Utah has county-by-county water goals. Is your county hitting them?
Part 2
How we talk about conservation in Utah
Part 3
“At the end of the day, conservation costs money.”
Love storytelling? Curious about how water shapes life in the West? Want to work with a small team of journalists who are fascinated by the snowpack, rivers, reservoirs, and the stories behind them?
The Water Desk at the University of Colorado Boulder’s Center for Environmental Journalism is looking for a Spring 2026 Intern, and we’d love to hear from you.
As our intern, you’ll work alongside The Water Desk’s leaders, helping track water news, supporting reporting projects, writing your own stories, and contributing ideas to strengthen coverage of one of the West’s most important issues.
What you’ll do:
Dig into research for your own stories and our team’s special projects
Support our social media, website updates, and general communications
Help wrangle details for journalism training programs and workshops
Contribute to brainstorming sessions and team discussions
Bring curiosity and creativity to everything you do
What we’re looking for:
Strong writing skills and a sharp eye for detail
Genuine interest in journalism, water, climate, or environmental issues
A student who’s organized, comfortable working independently, and eager to learn
Bonus points if you’ve dabbled in reporting, photography, video, data analysis and visualization, or digital communications
This paid internship is open to CU Boulder students and offers flexible hours (approximately 10-15 per week) throughout the spring semester. It’s a great opportunity to build real-world experience in environmental journalism, storytelling, and digital media.
Ready to apply?
Fill out this online application, which asks for your résumé, a brief cover letter, and two work samples.
Come help us tell the story of water in the West.
Deadline for submissions: December 31, 2025 at 11:59 p.m. MT
A high-severity burn in Colorado’s Rocky Mountains. Wildfires are altering the snowpack, a crucial source of water in the West. Photo by Arielle Koshkin.
As the American West warms due to climate change, wildfires are increasingly burning in higher-elevation mountains, charring the watersheds where the region’s vital snowpack accumulates.
A new study has found that in the immediate aftermath of fires across the region, the snowpack disappears earlier in burned areas. This change can threaten forest health and affect the downstream farms, cities and species that rely on the snowpack for their water, according to other research.
Scientists who study the effects of wildfires on the snowpack and streamflows are finding that the story is complex and nuanced. The impacts can vary greatly across the West’s diverse ecosystems and topography. Plus, each wildfire burns differently, so the severity of the blaze is another critical factor.
While streamflow volume typically increases after a wildfire, the peak flows come earlier in the season, and the water may be clogged with sediment that can harm wildlife and water infrastructure.
The new study, published in the September 17 issue of Science Advances, used satellite data to track when the snowpack disappeared each season and examined how that timing changed after a fire burned through forests. The research also concluded that warming temperatures due to climate change will further accelerate post-fire melting.
In the first year after a fire, the researchers found that under average winter conditions, snow melts earlier in 99% of the snow zone. “Postfire snow cover loss is more extreme in relatively low-elevation, warm environments compared to that in high-elevation, cold regions,” wrote the researchers from the Colorado School of Mines and the University of Colorado Boulder’s Institute of Arctic and Alpine Research.
The loss of the forest canopy due to a fire can actually increase snow accumulation on the ground below because scorched trees that are missing branches and needles intercept fewer falling snowflakes. But opening up the canopy changes the flow of energy in the forest by exposing the underlying snowpack to more solar radiation that can melt the snow.
Wildfires also cause soot and darkened debris to fall on the snowpack, which reduces its reflectivity, allows more heat to be absorbed and leads to quicker melting. Burned forests are also more susceptible to wind, which can further erode the snowpack.
“It’s basically just a big energy balance puzzle, but it seems like that increase in sunlight and decrease in the reflectivity of the snow are both leading to (an) earlier snow disappearance date,” said lead author Arielle Koshkin, a doctoral candidate in hydrologic science and engineering at the Colorado School of Mines. “Even if we do see more snowfall in the forest, it’s not overriding those energy balance changes.”
The study notes that previous research has found that the acreage of Western forests burned in the seasonal snow zone increased by up to 9% annually between 1984 and 2017, with the biggest rise in burned area occurring above an elevation of 2,500 meters (8,202 feet).
“Fire is burning higher and higher in elevation, which increases this overlap between where burned forests are and where it snows,” Koshkin said.
Stephanie Kampf, a professor of watershed science at Colorado State University who wasn’t involved in the study, said the findings are “pretty consistent with prior research” showing that snow disappears earlier after a fire and that lower-elevation locations with more “transitional” snowpacks are more vulnerable. “This study shows it really nicely with a big dataset,” Kampf said.
Climate change speeds up melting
Looking ahead, the authors project that post-fire melting will accelerate further as the West gets hotter due to rising atmospheric levels of greenhouse gases. If warming increases by 2 degrees Celsius—something that’s possible by the middle of the 21st century under some emissions scenarios—“73% of the snow zone would experience more extreme earlier postfire snowmelt compared to historically average conditions,” according to the paper.
“Under two degrees (Celsius) warming, the areas that already showed large changes are going to show even larger changes,” Koshkin said. “That warming is going to really have (an) impact on those warmer snow climates. So think maritime, Cascades, Sierras, comparative to the higher, colder, Rocky Mountain West.”
Previous research has also looked at what happens to the snowpack after a fire and found that the snow disappearance date moves up four to 23 days. Some of those studies have used ground-based observations, but the papers typically focused on one to three fires. Other research has examined snowpack readings from the automated SNOTEL network, but those snow sensors are usually placed in gaps in the forest canopy and may not capture the diversity of the West’s landscapes.
This new study relies on images captured by the MODIS instruments aboard two satellites to provide a Westwide look at wildfire’s effects. Currently, satellites cannot measure the water content of the snowpack, known as the snow water equivalent. But repeated satellite imagery can detect whether snow is present on the ground, allowing researchers to measure when the snowpack disappears during the year.
“I was really interested in seeing if we could leverage remote sensing to look at it on a pixel-by-pixel scale across the whole Western United States to really try to understand, are we seeing the same responses in the Pacific Northwest as in Colorado?” Koshkin said.
Each pixel in the MODIS satellite imagery represents a square on the ground with 500-meter (1,640-foot) edges. That’s a somewhat coarse resolution for measuring the snowpack, which can vary dramatically over very short distances, but the satellites provide daily or near-daily coverage.
While satellite data offers broad coverage of the region, it has significant limitations.
“The satellites can’t really peek underneath the forest canopy,” said Anne Nolin, a professor in the geography department at the University of Nevada, Reno, who wasn’t involved in the study. (Koshkin is a former student of Nolin’s.) “The other issue is that the satellite data can’t measure snow at times when there’s rain occurring or anytime there’s cloudiness. And so if you have a rain-on-snow event that’s changing your snowpack, which we’re having more and more, and which we would anticipate to occur more frequently, then you’re probably missing short-term changes in snowpack.”
Nolin said that the satellite-based estimates of the snowpack were “likely to be inaccurate in places where you have remaining forest, and especially in low-elevation snow zones and under warmer winter conditions.” That’s because previous studies have found that in warmer forests, the snow melts off under the canopy early, but it’s retained in the gaps between the trees, so the algorithm used to process the satellite imagery can overestimate the amount of snow in the pixel. “There’s less snow there than you think,” Nolin said.
Stark regional differences
Elevation, temperature, burn severity, vegetation type and the amount of incoming solar radiation are among the drivers explaining when the snow disappears. The variability of these factors across the West may help explain why previous studies have found such a wide range in the timing of the snow disappearance date.
“Everywhere we looked was disappearing earlier, but there were these kind of hotspots that disappeared way earlier,” Koshkin said. “I think the disruption in streamflow from these earlier melting-out pixels will be much more significant in Oregon, Washington and California.”
Wildfires had the biggest effect on the snowpack during the first five years after the blaze. In the first year after a fire, the snow disappearance date advanced by an average of 3.3 days. That might not sound like much, but the figure is just an average for the entire West—in some parts of Northern California and Oregon, the snow disappeared up to two weeks earlier.
Over time, the effects of fire declined. Ten winters after a blaze, for example, the average snow disappearance date moved up by less than a day.
While the advance of the snow disappearance date was most pronounced at lower elevations, the snowpack actually persisted slightly longer in some burned areas in Colorado and Utah, where the colder temperatures at higher elevations can insulate the snowpack from changes.
The finding that some higher elevation locations had a later snow disappearance date “would definitely be something to explore because everything that we know so far suggests that snow disappearance should be earlier after a fire,” Kampf said.
Higher elevations may be less vulnerable to an early disappearance of the snowpack due to late-season storms. “Here in Colorado,” Kampf said, “we get a fair amount of spring snow, and so that’s one of the reasons why we’re not as sensitive because sometimes that snow just comes in May and it resets everything and you don’t see the big change in snow disappearance date.”
Another factor in explaining the regional differences is the West’s diversity of vegetation. “The forests are different in places that are colder, so you have different tree species and different densities of forest and different ecosystems in general,” Nolin said. “The northern tier of states and the high country—that’s where you would be probably seeing the least amount of change. It doesn’t mean, though, that you have the least amount of fire because some of these places, especially in places like Idaho and Washington state, have significant amount of fire, and there’s some interesting studies that have shown earlier snowmelt in those locations as well.”
A large burn scar in the Northern Rocky Mountains. Post-fire changes to the snowpack vary significantly across the West’s diverse landscapes. Photo by Arielle Koshkin.
How wildfires change streamflow
Previous research has found that wildfires can significantly alter the timing and magnitude of runoff in burned watersheds, but scientists are still unraveling the details.
“If you burn down the forest, you don’t have as many trees that are using that water,” Nolin said. “You probably expect the streamflow to be earlier because the snow’s melting off earlier.”
Fires can not only kill trees and ground cover that would absorb water—they can also eliminate organic material in the soil, which causes the ground to become more water repellent and makes the snowmelt more likely to run off into streams.
A 2022 study that examined 72 forested basins that burned across the West found that average streamflow was significantly higher after a wildfire for an average of six years. The increase in streamflow was greater in areas where the extent of wildfire was larger. That study also found that the annual acreage burned by wildfires in the West skyrocketed by more than 1,100% from 1984 to 2020.
Kampf said more research is needed to understand how streamflow changes after a fire. “We don’t have all those interactions figured out yet, but there have been some studies that have shown that streamflow actually decreases after fire,” Kampf said. “We certainly know it will affect streamflow timing, but the amount of streamflow we’re less sure.”
Fire intensity is one key determinant of subsequent streamflow.
“If the forest is totally torched, then the increased solar radiation that’s coming into the snowpack is going to have a much bigger effect than if the trees still have live branches on them,” Kampf said. “Similarly, when you get down to the soil, if the soil is totally burned to a crisp, then its infiltration impacts will be much greater than if a lot of the litter and other stuff in the soil is still there.”
Nolin said she would have liked to see the authors distinguish between areas of high, moderate and low burn intensity.
“When you see photographs of burned areas, we tend to show the photos that are most dramatic with just charred trunks that have (been) left behind, but in fact, most fires are mainly low to moderate burn severity that maintain the forest canopy,” Nolin said. “To not distinguish between different burn severities and to indicate that it’s all about the canopy being burned off and all of this carbon shedding on the snow—I think that stretches the results.”
The speed of vegetation recovery also shapes how the snowpack and streamflows respond to wildfire over time.
“If it’s a forest type where the vegetation can respond quickly and come back, that’s going to be a really different response than if the vegetation is slow to grow,” Kampf said. “Here in Colorado, we have some fires where it’s not coming back as forest at all, and where there are just no seedlings, and so we would expect the fire effect on snow to persist for a long time because we just don’t have trees coming back.”
The post-fire effects on streamflow tend to be localized, so it can be difficult to detect their effects on major river basins.
“Even though the fires we’ve been experiencing have been really large, they’re still not huge compared to the size of the watershed as a whole,” Kampf said. “If you looked at something like the Colorado River Basin, it might be hard to detect the fire effect on the flow because there’s such a huge area that’s contributing to that flow. So in terms of how water is managed in forecasting and dam operations, I don’t think we’re there yet in terms of knowing how to account for fire.”
A major worry for water managers is the threat of high-intensity fires burning through dense stands of forest in the watersheds above their systems.
“Those are places that water managers are concerned about because if the forest burns, then they experience problems with post-fire erosion and sedimentation and harms to water infrastructure, so it’s kind of a different side of the water management issue,” Kampf said.
Impacts on ecosystems
Besides posing challenges for water managers, wildfires can have profound effects on wildlife and forest health.
For aquatic ecosystems, “having a shift in the timing of when flow is coming in could also have an impact,” Kampf said, but “probably the greater impact is when that flow is bringing in with it a lot of sediments that are changing the habitat more profoundly.”
More rapid melting of the snowpack after a fire can also lead to a longer dry season for forests.
“If the snow disappears earlier, plants will start greening up sooner,” Kampf said. “If they’re not getting a lot of summer rain, they may find drier conditions later in the growing season that can stress plants.”
In addition to snow disappearing earlier due to fires, Nolin said the weather in November is getting drier. “If you have an earlier snow disappearance date and a later snowfall date, that dry season’s really getting quite a bit longer, and so it means that you have a decline in forest health and you also have an increase in the potential” for a longer fire season, Nolin said.
How burned ecosystems will respond to fire remains an open question as the climate continues to warm. In many parts of the West, decades have passed since flames swept through a forest, but trees have yet to return.
The burned trees may be centuries old, “and the climate was different than when those little seedlings sprouted and became the big trees that ultimately were involved in the fire,” Nolin said. “They grew initially under a different climate, and we don’t have that climate anymore, so we might see a lot more shrubs.”
Nolin said the paper “used a very simplistic approach to looking at future impacts on snow” by only examining what will happen under 2 degrees Celsius of warming. Climate change will also alter such factors as relative humidity and precipitation, so including these other effects “would’ve been more nuanced and perhaps a little more supportable,” Nolin said. She would have liked to see the results for various temperature increases up to 4 degrees Celsius, noting that mountains are warming faster due to climate change, and a key question is whether rain or snow will fall under warmer conditions.
“Just having a single temperature change to look at helps us understand the impacts of temperature, and that’s great, but there is a lot more to be done in this area,” Nolin said.
This story was produced and distributed by The Water Desk at the University of Colorado Boulder’s Center for Environmental Journalism.
Ice forms on the banks of the Crystal River a few miles south of Redstone, Colorado on October 29, 2025. (Caroline Llanes/Rocky Mountain Community Radio)Rocky Mountain Community Radio’s Caroline Llanes reports from western Colorado
Tree rings can tell a story. Wide bands signal a wet period, while narrow ones show a drought. Whole ecosystems can be encoded in trees. In Western Colorado, scientists are examining trees to find out more about the environment’s story in an effort to protect the river they stand along.
On the banks of the Crystal River, a few miles south of the small town of Redstone, David Cooper surveyed a spruce tree with its roots exposed.
“OK, our first victim,” Cooper said as he examined the roots and directed volunteers where to start digging.
Sheehan Meagher (left) and David Cooper (right) figure out the best place to start digging to uproot a large spruce tree. (Caroline Llanes/Rocky Mountain Community Radio)
Cooper has been a professor at Colorado State University for over thirty years, focusing on wetland and riparian ecology. For this study, he’s been working with Dave Merritt of Functional River Ecology and Peter Brown of Rocky Mountain Tree Ring Research. The group is trying to get to the root of how this tree and the river are connected.
Using clippers, shovels and metal poles, volunteers like Sheehan Meagher helped unearth the tree completely.
“For me, it was kind of hard the first day because I was like, ‘Oh, we’re digging up these trees,’” Meagher said. “And I was like, ‘I don’t know how I feel about it. I’m a tree hugger.’”
Despite Meagher’s initial hesitation, he’s enjoyed getting to see science in action. And, he says it’s for a good cause.
“I was like, ‘Alright, where’s the spruce that wants to give its life for science so that we can study this river and hopefully prevent this river from ever being dammed,’” he said.
This spruce tree on the banks of the Crystal River already has its roots exposed, giving volunteers a head start in digging it up. (Caroline Llanes/Rocky Mountain Community Radio)
The Crystal River is one of the few rivers in Colorado that doesn’t have any major dams; large stretches of it are still pristine. As demand for water increases amidst a warming climate, policy makers often scan the landscape looking for new supplies. A free-flowing river like the Crystal can be an attractive option to supplement fast-growing communities.
Proposals to dam the Crystal and create a reservoir have cropped up over the years, most recently in the early 2010s. Those have been shelved due to cost concerns and local opposition, but locals say it’s only a matter of time before someone else tries. They want to secure federal protections from Congress to protect the Crystal in perpetuity in the form of a “Wild and Scenic” designation.
Peter Brown and David Cooper examine the cross-section of a spruce tree, and estimate its ring count. (Caroline Llanes/Rocky Mountain Community Radio)
At the heart of what Cooper, Brown and Merritt are trying to do with this study is establish the relationship between the trees and the Crystal’s natural hydrologic rhythm, which wouldn’t exist if it were dammed or diverted.
“For most of the work we’ve done over the last 30 or 40 years, we’ve shown that it’s mostly big floods that disturb the ground and create habitat for establishment and allow these trees to get established,” Cooper said.
Once the group got the tree out of the ground, they used a chainsaw to cut near the roots to get a cross-section. Brown and Cooper examined the cross-section.
“You can see the rings real well here,” Cooper said, pointing with his finger. “Look how small they are. So that tree might be 25 or 30 years old.”
The trees that Cooper, Brown, and Merritt uproot are cut into smaller pieces and labelled, before being transported to a lab for further analysis. (Caroline Llanes/Rocky Mountain Community Radio)
But according to Cooper, these rings don’t tell the full story. These trees have been cut by beavers. They’ve been knocked over and buried by rockslides in this narrow valley. The stem itself doesn’t reflect the tree’s true age. Cooper is looking for the very oldest part of the tree, called the pith. Once that is exposed, researchers can compare the cross section to the Crystal’s water record. Cooper says they’ll go year by year, and see whether each ring correlates with a wet or dry year.
“There’s big floods and dry years and so if you’re just within one or two years, you have really no idea what kind of flow regime was required to establish the plant,” he explained. “So that’s why we need to know the year. Not, not plus or minus one, the year. There’s really no room for error.”
In the same way that the river shaped the trees by spurring or constraining their growth, Cooper says these trees in turn shape the river, and make it what it is.
“You see that the trees grow around the rocks and then sediment accumulates above them,” he said. “The roots of these plants hold this bar together. Without tree roots, this whole thing would be mobile. So the roots are building the floodplain and creating all of this habitat.”
Volunteer Sheehan Meagher looks around the banks of the Crystal River for a good tree to dig up on October 29, 2025. (Caroline Llanes/Rocky Mountain Community Radio)
It could be awhile before a proposal to secure protections for the Crystal goes before any federal agency. But for locals like Sheehan Meagher, the time spent on this research is well worth it.
“Hopefully the research shows that these mass flooding events are critical to establishing this type of habitat,” he said.
Any future dam would disrupt that, he said. Getting the science to back up that claim is worth taking a tree or two, he said.
“Please give your life to science, cottonwood,” he said, laughing.
If there’s the will and the funding, Cooper and his team will be back next year, documenting the story of the river and its trees, and building the case for its preservation.
This story was produced in partnership with The Water Desk at the University of Colorado Boulder Center for Environmental Journalism.
Copyright 2025 Rocky Mountain Community Radio. This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah, and New Mexico, including Aspen Public Radio.
The Colorado River fills Glen Canyon, forming Lake Powell, the nation’s second-largest reservoir. The reservoir could drop to a new record low in 2026 if conditions remain dry in the Southwestern watershed. (Alexander Heilner/The Water Desk with aerial support from LightHawk)
Heavy autumn rains brought relief to drought-plagued portions of the Southwest, but across the Colorado River basin ongoing water supply concerns still linger amid tense policy negotiations and near record-low reservoir storage.
Even after accounting for the heavy rain, 57% of the Colorado River watershed remains in severe drought, according to the U.S. Drought Monitor. More than 11% of the basin is in extreme drought.
A less than average upcoming snow season combined with a dry spring or early summer in 2026 could create conditions for another low runoff year. The Colorado River’s headwaters saw a weak snowpack last winter, which contributed to one of the worst spring runoff seasons on record in 2025. Drought conditions spread and worsened into summer throughout the southern Rocky Mountains.
Peter Goble, Colorado’s assistant state climatologist, explained that the recent rainfall “certainly recharged soils,” in some watersheds.
Streamflow in the Animas River and Rio Grande increased significantly following the October rains and flooding. Rain in southwest Colorado, particularly around Pagosa Springs, brought flooding that damaged homes and downtown businesses. Rain gauges near the San Juan Mountains recorded 7 to 10 inches of precipitation from October 9-15.
“We would love to see this rain come over a more steady incremental period,” Goble said. “But oftentimes it is these flooding events that kind of put the kibosh on a drought more locally.”
The flooding erased drought designations on the Drought Monitor map in those localized areas, but basinwide drought conditions tell a different story. Dry soils, depleted reservoirs and winter weather forecasts continue to cause water managers to worry.
Even with the recent rain, soils in many parts of the Colorado River basin remain dry. Soil absorbs moisture almost like a sponge. When the soil moisture is low, spring runoff soaks into the soil, saturating the ground first. Soils that are more saturated lead to more water filtering into streams and reservoirs when runoff occurs, making the process more efficient.
“We’re still going to need a good snowpack in order to be set up nicely, but this (rain) improves our outlook for the efficiency of that snowpack,” Goble said.
Federal forecasts show the possibility of a mild La Niña through February. The climate pattern occurs when Pacific Ocean waters cool down and alter global weather conditions. La Niña patterns often impact the amount of snowpack accumulation in the coming year. The southern part of Colorado is often drier in a La Niña year while northern areas, around Steamboat Springs, typically see snowier conditions.
The stakes for an above average runoff next year are high. The two biggest reservoirs in the country, Lake Powell and Lake Mead have steadily declined over the last 25 years. Powell is currently at 29% of its capacity and Lake Mead is at 32%. A lessened runoff could push them dangerously low.
While the rain slightly alleviates local drought, it’s “only a drop in the bucket when it comes to refilling Lake Powell and Lake Mead,” Goble said. “We’re still going to see those regional water shortages persist.”
Glen Canyon Dam holds back the waters of Lake Powell, which has reached critically low levels in the last three years. The reservoir serves downstream water use in Arizona, California, Nevada and Mexico. (Mitch Tobin/The Water Desk)
If water levels continue to decline in these larger reservoirs, the dams’ infrastructure is threatened and the hydropower turbines can’t be used. Lake Powell, for example, has different outlets installed so water can be released in low conditions, however they are not designed to be the main outlet source. New federal projections show it’s possible Powell’s levels could drop low enough to cease hydropower production as early as October 2026, if conditions remain dry.
“They could reach levels they have never reached before and potentially reach catastrophic levels,” said John Berggren, regional policy manager for Western Resource Advocates.
In response to extremely low water conditions, it’s possible water from upstream reservoirs in Colorado, Wyoming and New Mexico could be released to support Powell’s hydropower turbines.
“We are seeing a new normal because of climate change, because of aridification,” Eric Kuhn said, former general manager of the Colorado River District, on the state’s Western Slope. In 2022, the basin saw similar drought conditions.
“We are back where we were just a few years later,” Kuhn said. “The system is slipping away.”
The basin states are also engaged in negotiations for new operating guidelines for the Colorado River, set to be in place by 2027. Given the ongoing drought conditions, water experts say the two reservoirs cannot wait for new guidelines.
“Don’t forget the short term problem while you are focused on a long-term agreement,” Kuhn said. A recent research paper, co-authored by Kuhn, highlights the need for urgent consumptive cuts basinwide. “We have got to figure out what’s going to happen next year if next year happens to be dry.”
This story is produced and distributed by The Water Desk at the University of Colorado Boulder’s Center for Environmental Journalism.
Colorado Parks and Wildlife invasive species specialist Maddie Baker looks for zebra mussels near the shore of East West Lake in Grand Junction, Colorado. (Caroline Llanes / Rocky Mountain Community Radio)
On a bluebird day at West and East Lake in Grand Junction, Maddie Baker throws a plankton tow net into the water, and drags it back to her.
“This is made of a 64 micrometer mesh, so that allows us to trap the veligers in their juvenile form, where they are microscopic and invisible to the eye,” she said.
Baker is an invasive species specialist for Colorado Parks and Wildlife. A veliger is the larval form of many kinds of mollusks, including the invasive—and pervasive—zebra mussel.
Baker doesn’t have to tow the plankton net to know the mussels are here. She picks mussel after mussel off of a concrete platform that gives anglers access to the lake. These zebra mussels are small, about the size of dimes (though they can grow bigger) and the little brown stripes that give the species their name are only just visible.
“It sucks,” she said. “It’s a very unfortunate realization for us to come to. And it shows us that this population is already well established in this body of water, if we can find adults with relative ease.”
Part of the reason water and wildlife managers hope to avoid zebra mussel infestations is how durable they are. Baker said they attach to hard surfaces using bissell threads.
“It’s organic material that they secrete from their body that forms both a physical and chemical bond with whatever hard surface they’re attaching to,” Baker said. “So this does last for their life and beyond.”
Maddie Baker, Colorado Parks and Wildlife invasive species specialist, holds five adult zebra mussels in her hand. (Caroline Llanes / Rocky Mountain Community Radio)
Zebra mussels are bad news for western waterways. Spread mainly by hitching rides on watercraft, the fast-reproducing mollusks clog water infrastructure, cling to marinas and docks, and outcompete native species. Colorado has taken costly measures to keep its lakes and rivers free of the mussels, but recorded the first official infestation in the state’s portion of the Colorado River this year.
Quagga mussels, zebra mussels’ close relatives, and other aquatic nuisance species, have made their presence known at reservoirs in the Colorado River Basin, like Lake Powell and Lake Mead. Lake Mead has been infested with quagga mussels since 2010, and Lake Powell was officially considered infested in 2012.
“At places like Lake Powell, where the water level fluctuates pretty often, you will see mussels that are still attached to canyon walls even after they’re already dead,” Baker said of the strength of bissell threads. “Just because those bonds are really lasting.”
Another alarming zebra mussel trait is how fast they reproduce.
“Each one of these can produce a million offspring and then each of those million offspring produces a million every single year,” Baker said, showing off a handful of zebra mussels, freshly plucked from the concrete platform.
“The notion of these attaching inside of our pipes or hydroelectric infrastructure–dams–is very concerning,” she says.
Zebra mussels originally came to North America from Eastern Europe through shipping vessels travelling in the St. Lawrence Seaway. In the Great Lakes region, they’ve wreaked havoc on water infrastructure, and caused millions of dollars in damage.
Bruce Johnson is an Aquatic Invasive Species Lieutenant with the Utah Division of Wildlife. He said prevention and education programs at popular recreation areas like Lake Powell have been crucial in keeping quagga mussels contained.
Data from Lake Powell shows just how far boaters are traveling, and therefore, how widely contaminated vessels potentially carrying the microscopic veligers can spread the invasive species, Johnson said.
“Approximately 40% of our boaters that we document at Bullfrog (Marina) are Colorado-registered watercraft,” he said. “We have a high percentage of boaters that are coming from Colorado down to Lake Powell—an infested water body—and then traveling back into Colorado.”
Back in East and West Lake in western Colorado, Morgan Hoffmann holds up a little piece of pipe that stays in the water for mussels to attach to in their juvenile stage, when they’re still too small to see with the naked eye. It’s a method to detect when a water body might be infested. Hoffmann is an Early Detection and Rapid Response specialist with the state.
“On these, we’re really targeting the settler stage of the zebra mussels,” Hoffman says. “So when we pull these out of the water, we feel the pipe and we’re looking for a sandpaper-like texture on that stage of the mussel.”
East West Lake in Grand Junction connects to the Colorado River via a nearby canal. Zebra mussels have already attached to the concrete infrastructure that connects the lake and the canal. (Caroline Llanes / Rocky Mountain Community Radio)
There are five bodies of water in Colorado that are officially considered “infested,” which means that the zebra mussels have established a reproducing population, with multiple life stages detected. In addition to West and East Lake, the list includes Highline Lake, Mack Mesa Lake, the Colorado River from the 32 Road bridge to the Colorado-Utah state line, and a private body of water in Eagle County.
The Colorado River is considered mussel-free from its headwaters to the confluence with the Roaring Fork River in Garfield County. Downstream of that point, until the river flows through the Grand Valley, CPW hasn’t found any adults, but they have found the veligers.
West and East Lake drains into the Colorado River, via a nearby channel. The Colorado River is already under tremendous pressure. Climate change is contributing to a historic drought, and there’s a lot of demand for water from both agriculture and growing communities throughout the Southwest.
Zebra mussels add another layer of stress to the river’s increasingly fragile aquatic ecosystems, said Rachael Gonzales, a CPW Public Information Officer.
“(Zebra mussels) also have an impact to the environment, and specifically to the water because they’re filter feeders,” she said. “So they are filtering every good nutrient that our native fish need to survive.”
It’s because of these threats that CPW is taking zebra mussels so seriously, and has increased its sampling efforts all the way to the river’s headwaters. Hoffmann oversees the program, along with the agency’s testing lab in Denver.
Morgan Hoffmann holds up a piece of pipe that functions as a landing pad for the juvenile stage of zebra mussels. Because they’re still too small to see, she and other CPW specialists feel for the sandpaper texture that indicates the mussels’ presence. (Caroline Llanes / Rocky Mountain Community Radio)
“I’m feeling confident in our program overall,” she said. “Since we found them, it’s kind of proven that our sampling and monitoring program is effective and the way we’ve designed it is working. So we’re detecting these pretty quickly, which is what we want to do.”
Robert Walters, CPW’s invasive species program manager, said that because of the severity of the threat, they’ve been able to access additional resources, including from the federal government.
“Because we are collaborating with them so regularly, we’re not only able to do what we know or are more traditional sampling technologies, but we are also able to utilize those that are out there on the cutting edge to give us the highest probability of finding these things out in the environment,” he said.
He said they worked directly with the federal Bureau of Reclamation to develop testing methods to detect zebra mussel DNA, and they worked with the U.S. Geological Survey to deploy an autonomous sampler on the Colorado River—a new piece of technology.
In 2026, Walters said, CPW has plans to install a dip tank at Highline Lake in Grand Junction to clean boats and watercraft. It allows more complicated vessels to be decontaminated without CPW staff needing to understand how the boat works.
It’s the result of ongoing regional collaboration and knowledge-sharing between Colorado and other states on how to best respond to this emerging threat. Utah has six such tanks, the first installed at Lake Powell in 2021.
Bruce Johnson, with the Utah Division of Wildlife, said there are three more on the way, in addition to the one in Colorado.
“We’re the only ones in the world to build dip tanks for decontamination,” he said.
Johnson said that sharing knowledge is critical for big projects like the dip tanks, but regional leaders are in frequent communication about day-to-day operations when it comes to preventing the spread of aquatic invasive species.
“Talking about new developments, boater contacts, information, biological advances, options for conducting inspections on those watercraft and any issues that we’re having with their different registered boaters,” he listed.
Johnson said that he regularly talks with regional partners in Colorado, Arizona, Idaho, Nevada, and Wyoming, along with federal partners like the U.S. Fish and Wildlife Service, the National Park Service, and the Bureau of Reclamation.
“That’s the beauty of the program, and why we’re so strong, and why we have held new discoveries, detections, and infestations to such a limited number here in the Western U.S. is because of that,” he said.
And it goes beyond just data and knowledge.
“We’ll actually coordinate our funding efforts,” Johnson said. “If there’s a new grant or funds that come into play, we’ll discuss our options and decide, ‘Okay, does this better fit Colorado? Is Colorado a better option to take a higher percentage of these funds?’ And Utah, we’ll take less funds because we know they can put it to better use than we can. And so we don’t fight over that.”
Colorado offers tools for recreationists looking to clean, drain, and dry their gear. They also offer free towels reminding people of the steps involved to properly remove any mussel remnants. (Caroline Llanes / Rocky Mountain Community Radio)
But Gonzales, the CPW spokesperson, wants to emphasize that it’s not just professionals out in the field that can make a difference. Zebra mussels spread from one body of water to another primarily through people recreating on the state’s waterways.
“We see a lot of fall fishing, we also see waterfowl hunting,” Gonzales said. “Taking a couple extra minutes when you’re done and cleaning your waders is going to go a long way to protect our bodies of water.”
The more the public can help with the risks, Gonzales says the better they can protect Colorado’s infrastructure, its native species, and a way of life that depends on healthy waters.
CPW lists gear-cleaning station locations across the state on its website, and the agency is asking the public to report any potential sightings of zebra mussels in local bodies of water.
Copyright 2025 Rocky Mountain Community Radio. This story was shared via Rocky Mountain Community Radio, a network of public media stations in Colorado, Wyoming, Utah, and New Mexico, including Aspen Public Radio. It was produced in partnership with The Water Desk at the University of Colorado Boulder.
In late May, as the outside temperature approached 100 degrees, Arizona’s top water policy officials gathered in an air-conditioned Phoenix conference room. Their purpose that day was to decide whether the state should extend a longstanding drought emergency declaration. The standard indicators – minimal precipitation, low reservoirs, the second-hottest 12-month period on record – were not encouraging.
Halfway through the 90-minute meeting, gallows humor lightened the mood.
Ed Gerak, executive director of the Irrigation and Electrical Districts Association of Arizona, which represents power providers that receive federal hydropower from Colorado River dams, had the mic. Gerak shuffled through a matter-of-fact slide deck that explained how hydropower output from those dams, particularly the two largest, Hoover and Glen Canyon, has been diminished by shrinking reservoirs.
In the middle of the presentation, Tom Buschatzke, director of the state water agency, noticed a misspelling on the screen. He asked Gerak to scroll back to the previous slide.
“Is that Freudian?” Buschatzke asked. “Or did you put ‘Hoover Doom’ on purpose?”
For the millions of water and power customers in the Colorado River, it certainly feels that way. The typo, which received a knowing laugh from those in the room, cuts close to the truth.
The mood in the Colorado River basin is dreadful. River forecasts consistently overestimated runoff this year. Reservoirs are on a knife’s edge. The basin, on the whole, is drying. That’s frightful for the 40 million people and 5 million acres that the river supplies with water. But it’s also worrisome for electricity generation. Lakes Mead and Powell, the basin’s two largest reservoirs, are approaching critical levels in which hydropower from their dams (Hoover and Glen Canyon, respectively) would be severely curtailed or altogether cease.
Losing a power source at a time of life-threatening heat, rapidly rising electricity demand due to data centers and population growth, and a changing energy mix would be a blow to the region, though hydropower is a small portion of overall regional electricity supply. The impact of a hydropower cut would be unevenly distributed.
The mood in the Colorado River basin is dreadful. River forecasts consistently overestimated runoff this year. Reservoirs are on a knife’s edge. The basin, on the whole, is drying.
Small utilities have the most to lose. They operate with tiny customer bases,rely primarily on the dams and are at the mercy of market rates to cover hydropower shortfalls..
“We’re absolutely concerned about Mead dropping more,” said Dane Bradfield, general manager of Lincoln County Power District, in eastern Nevada, one of those at-risk small utilities. Hoover provides about 70% of its power, down from 100% two decades ago. “It’s on our minds every day.”
At the other end of the spectrum is the Gila River Indian Community Utility Authority, which serves the Arizona tribe whose lands surround the Gila River. Federal hydropower is only about 12% of its supply and its solar generating assets are growing rapidly.
“We’re not too put off,” said Kenneth Stock, the utility authority’s general manager, about less electricity from Hoover and Glen Canyon.
Acting like responsible asset managers who value diverse portfolios both Lincoln County Power and Gila River Indian Community, not to mention other utilities in the basin, are changing with the times. As the power of flowing water becomes less reliable, they are turning to an energy resource that is almost always on in the Southwest during the day: the sun.
Opened in 1936, in the midst of a national economic calamity, Hoover Dam was an expression of American optimism, worker desperation, and engineering prowess. Everything about its construction was monumental, from the 135 vertical feet of river bed that was excavated for the dam’s foundation to the creation of a town and rail lines that housed workers and ferried supplies to the remote and inhospitable Black Canyon work site, some 25 miles southeast of Las Vegas.
Walking inside Hoover’s labyrinth of tunnels, visitors today feel the dam vibrate with the impounded force of the Colorado River moving through its turbines.
Ever since these turbines started spinning, Hoover Dam electricity has flowed to irrigation districts, Native American tribes, cities, and industries. One of those original recipients is Lincoln County Power District. The tiny utility serves about 5,000 people across more than 10,000 square miles of rural eastern Nevada.
Until 2005, when the Colorado River reservoirs were in the early days of their 25-year plunge, Hoover Dam was the only power source Lincoln County needed. The dam provided all the district’s electricity.
Lincoln County is getting less hydropower because the dams have less to give. Since the turn of this century, Hoover’s electrical output has dropped in tandem with Lake Mead’s decline. Annual generation is down by about half since 2000, the last year the reservoir was full.
Graphic by Geoff McGhee/The Water Desk
Since the turn of this century, Hoover’s electrical output has dropped in tandem with Lake Mead’s decline. Annual generation is down by about half since 2000, the last year the reservoir was full.
More reductions might be in store. According to the Bureau of Reclamation, the federal agency that manages the basin’s large dams, if Lake Mead falls another 23 feet – to elevation 1,035 feet – Hoover Dam’s capacity to generate electricity would be slashed by 70% from its current level.
The huge drop in hydropower output is due to physics. A higher column of water behind a dam provides more pressure to spin the electricity-generating turbines. Less water, less pressure, less hydropower.
Twelve of Hoover’s 17 turbines are older units that were not designed to operate at low water levels. They could be damaged in a process called cavitation.
Twelve of Hoover’s 17 turbines are older units that were not designed to operate at low water levels. They could be damaged in a process called cavitation. This happens when miniscule air bubbles form due to water pressure changes. When the bubbles rupture, they gouge the turbine blades. Reclamation estimated this summer that replacing these older turbines with low-head units that are not prone to cavitation would cost $156 million.
Power customers, whose rates pay for dam operations and maintenance, hope Congress will come to their aid. One option would be an appropriation for the turbine upgrades. Another, unlocking some $50 million in funds set aside for pension benefits for federal employees. Power customers argue that the pensions are funded through other means and that Reclamation needs congressional approval if it were to spend the money on new turbines.
A severe curtailment of Hoover power is not implausible. Every month, Reclamation updates its projection of reservoir levels over the next two years. The June update shows a 10% chance that Lake Mead dips below 1,035 feet in spring 2027.
Glen Canyon Dam, the other big hydropower asset in the basin, is also in trouble. According to Reclamation, hydropower there will cease when Lake Powell falls below elevation 3,490 feet. The latest Reclamation projections indicate a 10% chance of that happening by September 2026. The agency is considering its options for the low-water scenario, but not publicly saying much more.
“Reclamation is in the early stages of developing and comparing alternatives for producing power below 3,490 feet and providing additional water delivery flexibilities,” Jennifer Erickson, a Reclamation spokesperson, wrote in an email. “It would be premature at this time to speculate on those results.”
Solar power is growing as a share of utility electricity regionally and nationally, even as solar faces stiffening headwinds from the Trump administration
Amid the gloomy hydropower projections, one power source in the basin is producing real and measurable progress. Solar power is growing as a share of utility electricity regionally and nationally, even as solar faces stiffening headwinds from the Trump administration. The White House has pulled funding for renewables and cancelled projects.
Lincoln County Power District, attempting to diversify from hydropower, is one of several electric power cooperatives that will benefit from Apache Solar II, a solar and battery storage project of Arizona Electric Power Cooperative that is expected to go online in December. Lincoln County will receive 5 megawatts.
The power district is also building its own 2-megawatt solar project thanks to a congressional earmark in the 2023 budget bill. Dane Bradfield, the district’s general manager, expects construction to begin next spring and electricity to begin flowing in the third quarter of 2027.
Solar is helpful for the power district because it will reduce its purchased power costs, which tend to be more expensive. When hydropower shortfalls occur, the district has to buy electricity on the market. It does so a year in advance through something called a power hedge. Market purchases also take place during the year if hydropower is less than expected or demand is higher than forecast. If electricity demand is high, market prices can be expensive. The district instituted a surcharge on customers starting in 2022 that provides reserve funds for when purchased power costs exceed the district’s forecast.
To the south, Gila River Indian Community Utility Authority is in an even stronger solar-power position, one that developed rapidly.
In the last three years, solar in Gila River went from almost zero – “extremely minimal rooftop solar,” said Kenneth Stock, the general manager – to 30% of the utility’s supply.
Gila River is not stopping there. The utility just broke ground on a nearly 21-megawatt solar project that should be completed in 18 to 24 months, Stock said. That’s in addition to smaller developments such as installing a half-mile of solar panels atop the Casa Blanca Canal. The 1.3-megawatt project was funded by the Biden administration’s infrastructure bill.
Even Boulder City, the community that was founded to house workers who built Hoover Dam, is moving in that direction.
Federal hydropower from the Colorado River provides about half of Boulder City’s electricity, according to Joe Stubitz, the city utilities director. But the city picked up 5 megawatts of solar and battery storage in 2022 through a power purchase agreement, and it wants more.
“What we’re doing now is we’re looking for other options, preferably renewables, to supplement that loss of capacity at Hoover,” Stubitz said.
Peak Value
Though solar is blunting the pain from Hoover’s power decline for individual utilities, less hydropower has broader ripple effects.
Hydropower’s value is measured not just in megawatts. It’s measured in its ability to rapidly turn on and off to respond to changes in electricity demand. This ramping power is important for today’s electrical grid in helping weave increasing amounts of solar and wind into the power mix.
In the early evening, power demand spikes as people return home from work and turn on appliances. At the same time, the sun is setting and solar generation is dropping. Utility-scale batteries typically have only four hours of storage. In these situations, hydropower can be flipped on, ready to generate power in minutes.
“We really count on [hydropower] to help us meet our peak demand,” said Grant Smedley, director of resource planning, acquisition, and development at Salt River Project during a meeting in August of the Glen Canyon Adaptive Management Program work group.
Graphic by Geoff McGhee/The Water Desk
What happens if Glen Canyon stops producing hydropower? Utilities will need to rely on a more diverse power mix.
Salt River Project provides water and energy to 2 million people in central Arizona. Solar, wind, and batteries today are less than a quarter of its power portfolio. By 2035, that number is expected to reach three quarters, Smedley said.
What happens if Glen Canyon stops producing hydropower? Utilities will need to rely on a more diverse power mix, including, in some cases, fossil fuel resources, to ensure the reliability of the system.
“I think that’s just a reality that we’re going to have to operate in,” Smedley said. “And so we recognize that we may be in that future for a bit, but to the extent that it’s available, [hydropower] is a very important part of our portfolio.”
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.
Due to the megadrought, the boat ramp at Lake Powell’s Hite Marina lies far from the Colorado River in this October 2022 aerial view. Photo by Alexander Heilner/The Water Desk.
The American Southwest has been gripped by an epic drought that has lasted decades and strained the fast-growing region’s naturally limited water resources.
The megadrought—thought to be the worst in at least 1,200 years—has caused reservoir levels to plummet on the Colorado River and shriveled the Rio Grande. The dry times have also stressed imperiled ecosystems, heightened wildfire risks and curtailed outdoor recreation.
While the drought’s consequences are easy to see, its causes and prognosis are trickier to disentangle, requiring scientists to look deeply into precipitation deficits, rising temperatures and changing patterns in the atmosphere and ocean.
Long before humans began altering the climate with greenhouse gases and other air pollutants, the Southwest was subject to feast-or-famine weather featuring extreme dry spells, raising the possibility that this current drought is just part of that natural variability.
What scientists are exploring now is how the human touch is imprinted on the drought due to our ongoing transformation of the climate, atmosphere and oceans.
Three recent scientific studies identify human emissions as a key driver in the precipitation declines that have helped cause the Southwest’s current drought, which has been made much worse by rising temperatures due to climate change.
The papers, published in the July 9 issue of Nature Geoscience and the August 13 issue of Nature, focus on what’s been happening in and above the Pacific Ocean to help explain recent precipitation deficits in the Southwest. As carbon emissions continue to rise, all three papers conclude that human-caused warming is likely to make drought a more persistent feature in the decades ahead.
The three recent studies examine why changes in and above the ocean have shifted storm tracks and made the Southwest’s weather drier, but that’s not the whole story about the drought. The picture is even bleaker when we account for what’s happening to the region’s warming landscape and an increasingly thirsty atmosphere.
Another line of research has found that higher temperatures alone are causing the Southwest to “aridify” by drying out soils, boosting evaporation rates and shrinking the snowpack. Known as a “hot drought,” this aridification due to warming would be troubling enough for the Southwest’s water resources and society. But the three recent studies, which focus on precipitation shortfalls, add another level of worry: relief falling from the skies as raindrops and snowflakes appears increasingly unlikely.
The Southwest continues to experience drought conditions, according to this September 16 map from the U.S. Drought Monitor.
The PDO is a natural rhythm in sea-surface temperatures in the North Pacific Ocean that has warm and cool phases. The cycle, which is similar to the El Niño/La Niña pattern in the tropical Pacific, was thought to last about 20 to 30 years, but in recent decades it has predominantly been in the cool or “negative” phase, which tends to make the Southwest drier.
“The PDO has been locked in a consistent downward trend for more than three decades, remanding nearby regions to a steady set of climate impacts,” according to the study. “The ongoing, stubbornly persistent, cold phase of the PDO is associated with striking long-term trends in climate, including the rate of global warming and drought in the western United States.”
The conventional scientific understanding of the PDO holds that the pattern waxes and wanes largely due to natural “internal” variability. But this recent study, which relies on 572 climate simulations processed on supercomputers, argues that the PDO is, in fact, very much influenced by human activities and our air pollution. These external forces account for 53% of the variation in the PDO.
“Overall, we find that human activity is a key contributor to multi-decadal trends in the PDO since the 1950s,” according to the paper.
It wasn’t always this way. Between 1870 and 1950, the PDO’s changes were internally generated, with external forces explaining less than 1% of the variability.
“It seems like as long as emissions continue, we’re going to be stuck in this current phase of drought,” said lead author Jeremy Klavans, a postdoctoral associate in the Department of Atmospheric and Oceanic Sciences at the University of Colorado Boulder. “If emissions were to abate, we think that the PDO would be able to vary freely again, and drought would be, again, a thing of chance. There would be the chance to end the drought.”
The researchers say they used an “extraordinarily large ensemble” of climate simulations to isolate the signal of human-caused climate change from the noise of natural variability.
“It takes a really large ensemble to find this signal, and that’s because we think that the signal-to-noise ratio in climate models is too low,” Klavans said.
That’s distressing news for the region’s water managers, who are already grappling with limited supplies. “We expect there to be reduced water supply in the form of precipitation, including snowfall, in the next 20, 30 years, so as they’re making planning decisions for how to allocate water resources or what infrastructure to build, they should expect less precipitation,” Klavans said.
“It certainly seems that in the near term, given the choices that we’ve made, the PDO will continue to be stuck in drought,” Klavans said.
Study 2: Deep drought long ago offers insights for today
This isn’t the first time the Southwest has faced a megadrought.
During the mid-Holocene, there was a different external force at play: an increase in the amount of solar radiation hitting the Northern Hemisphere during the summer, which also altered vegetation patterns on the land.
In a process known as the Milankovitch Cycles, the Earth’s orbit and movement change regularly over the span of tens of thousands to hundreds of thousands of years. Like a spinning top, the planet wobbles. The tilt of its axis also oscillates back and forth. And Earth’s orbit around the sun alters from a near-perfect circle to a slightly more elliptical path.
The Milankovitch Cycles caused more sunlight to hit the Northern Hemisphere in summer during the mid-Holocene warming. One of the effects was a more vigorous West African monsoon and the greening up of the Sahel and Sahara deserts, which caused those areas to absorb more heat as the land surface darkened. Similar processes happened elsewhere. The paper concludes that this external forcing had a major impact on the Pacific Ocean and the PDO, similar to how human-caused warming is playing out today and into the future.
“People used to think that droughts in the Southwest were just occurring kind of like as a random roll of the dice, and now we can see that actually it’s like a pair of loaded dice,” said lead author Victoria Todd, a Ph.D. candidate at the University of Texas studying paleoclimatology. “This drought is occurring in wintertime, which is really important for snowpack in the Rockies and its role in Colorado River flow and Western U.S. water resources in general.”
The authors write that “our results suggest that these precipitation deficits will be maintained by a shift to a more permanent negative PDO-like state as long as hemispheric warming persists.”
“Such sustained drying and intense reductions in winter precipitation would have catastrophic impacts across the Southwest United States, particularly in the Colorado River Basin,” according to the paper.
Todd and co-authors investigated what happened during the mid-Holocene by using an analysis of leaf waxes extracted from the cores of lake sediments in the Rocky Mountains. Plants create waxy coatings on their leaves to minimize water loss and protect themselves. These hardy waxes can persist for ages when they’re deposited into sediments, allowing them to reveal critical clues about what the Earth was like when the plant was alive. By analyzing the leaf wax’s isotopes—special forms of chemical elements—researchers can paint a picture of precipitation patterns long ago.
The findings about the mid-Holocene and their analysis of modern climate projections led the researchers to conclude that current models underestimate the size of the precipitation deficits caused by warming. Both in the past and the present, the warming impacts the PDO and steers storms away from the Southwest.
If the Southwest’s drought were just due to natural variability—a fair roll of the dice—we’d expect the PDO to get unstuck eventually and for the dry spell to break. But the research concludes that pure chance is no longer governing the system. Humans are tilting the odds.
“If global temperatures keep rising, our models suggest the Southwest could remain in a drought-dominated regime through at least 2100,” co-author Timothy Shanahan, associate professor at the University of Texas’ Jackson School of Geosciences, said in a press release.
“Many people still expect the Colorado River to bounce back,” Shanahan said. “But our findings suggest it may not. Water managers need to start planning for the possibility that this drought isn’t just a rough patch—it could be the new reality.”
Lake Mead’s elevation has fallen as the region endures a megadrought. Photo by Alexander Heilner/The Water Desk.
Study 3: The effects of aerosols and tropical ocean warming
The study identifies two human-caused drivers for the shortfall in winter-spring precipitation in the region: the effects of aerosol pollution in the atmosphere and global warming’s impact on ocean temperatures in the tropical Pacific. These forces have weakened the Aleutian Low, the semi-permanent low-pressure system in the North Pacific that directs storms toward the Southwest when it’s stronger.
The study concluded that the post-1980 period in the Southwest has seen record-fast drying of soil moisture due to the precipitation declines and human-caused warming. Natural variability still plays a significant role in the Southwest’s precipitation, according to the researchers, but humanity is making its mark.
“We are not saying 100% it’s because of climate change or because of human emissions, but there’s a role from human emissions,” said lead author Yan-Ning Kuo, a Ph.D. candidate in atmospheric science at Cornell.
Aerosols may conjure deodorant sprays, but in this context, they refer to a broad class of airborne particles that are emitted by human activities, such as burning fossil fuels, and natural causes, such as dust from deserts or sea salt from the ocean.
Some aerosols, such as the sulfates emitted when coal and oil are burned, reflect incoming sunlight and can have a cooling effect. Others, such as sooty black carbon, absorb solar radiation and have a warming effect. Aerosols can also affect cloud formation.
In this study, the authors argue that aerosols can have a significant effect on the atmosphere as they drift eastward from Asia, where booming economies and lax regulations in some areas have caused air pollution to soar in recent decades.
“We actually feel like there’s a hope for good news on the precipitation side because as we clean up aerosols, precipitation might rebound a little bit,” said co-author Flavio Lehner, assistant professor in Cornell’s Earth and Atmospheric Sciences Department.
But while reduced aerosol pollution might help the Southwest’s drought, the emissions of greenhouse gases, such as carbon dioxide, keep rising, and warming temperatures continue to aridify the Southwest’s landscape.
“From a precipitation perspective, we might see a recovery in the next decade or two, but together with the continued warming, that might not help much with the drought,” Lehner said. “In none of these scenarios, I think everybody would agree, does it look like the Southwest is not going to be in trouble.”
A mountain stream in the San Juan National Forest near Pagosa Springs, Colorado, on July 26, 2025. Video by Mitch Tobin/The Water Desk.
Every spring, high-country streams and rivers in the American West begin to swell with water as the region’s snowpack starts to dissipate.
It’s easy to assume that the liquid flowing in these water bodies is just fresh meltwater emanating from the preceding winter’s snowpack.
But a recent study of 42 sites across the West finds that both the conventional wisdom and some traditional hydrologic models are wrong.
Most of that vital runoff—which sustains both ecosystems and economies—is actually groundwater that is many years old.
In the headwaters they studied, the researchers found the average age of the water in streams during snowmelt runoff was 5.7 years. Overall, about 58% of the runoff was derived from older groundwater that had been essentially pushed into the stream by the newer snowmelt.
“Contrary to the common assumption that snowmelt quickly contributes to runoff, stream flow during snowmelt in western US catchments is dominated by older groundwater,” according to the study, published in Communications Earth & Environment.
The spring and summer flows in the headwaters are certainly shaped by how much snow fell during the prior months. But the researchers argue that water managers need to account for longer periods of precipitation, the underlying geology and the resulting groundwater storage if they are to make more accurate forecasts of the runoff that supplies both natural and human communities downstream.
“We think it represents a fundamental change in how we think of water resources in the West,” said lead author Paul Brooks, a professor of hydrology in the Geology and Geophysics Department at the University of Utah.
People may think the melting snowpack “runs off the surface like spilling water on your countertop,” Brooks said, but “we know it’s more complicated than that.”
Many existing models of mountain hydrology assume that shallow soils sit on top of bedrock that lies close to the surface and doesn’t let much water through. Models also assume there’s minimal change in groundwater from year to year.
But Brooks said the study shows “without a doubt, there’s large and variable amounts of groundwater storage in the mountains.”
Implications for water management
The role of groundwater recharge and storage has important implications for how the West’s limited water supply is managed. Multiyear groundwater deficits could help explain why runoff in some basins has been far below average in recent years despite decent snowpack readings. Incorporating groundwater into runoff models could make predictions more accurate and inform how water is allocated over several years, not just season by season.
For Lake Powell and Lake Mead, the two largest reservoirs on the Colorado River and in the nation, “if you had the ability to predict several years in advance, you would change your management,” Brooks said. “If we can predict when there’s going to be more or less (water) available based on how groundwater storage responds to climate, we can look at a multi-year planning cycle rather than just starting all over again every year.”
“I’m very excited about this,” Brooks said. “It came out far better than I ever could have hoped for a sabbatical project.”
Keith Musselman, an assistant professor at the University of Colorado Boulder’s Department of Geography who wasn’t involved in the study, said that hydrologists studying riparian areas in lowland valleys have long described a “piston effect” in which newer precipitation pushes older groundwater out into a river.
“What Paul Brooks and his co-authors have done is bring that to the mountains, and mountains are important because they are really where the majority of our water in the West comes from,” Musselman said. “This paper kind of ties together a number of really important studies and highlights that there is this storage system that is important to consider when we’re thinking about, particularly, water conservation, water supply planning and, ultimately, climate change impacts on our ability to provide water to society.”
Overall, snowmelt-driven streamflow and groundwater recharge in the West’s mountain watersheds are “the primary water sources for 70 million people” across 10 states in the American West, according to the study. “This water supports municipal, industrial, agricultural, hydropower, and natural ecosystems powering a $9.8 trillion economy, trailing only the entire US and China in global economic activity.”
Dating the age of runoff
During his sabbatical, Brooks pursued what he called a “high-risk, high-reward” project. He traveled across the region to collect water samples from five major river basins that were then analyzed using tritium, a radioactive form of hydrogen.
This map shows the locations of the 42 headwater catchments that were sampled across five major drainage basins. Red and blue dots indicate if the underlying geology exhibited high or low permeability, respectively. Source: Brooks et al., 2025.
Tritium is a hydrogen isotope that occurs naturally in small amounts, but its prevalence in the atmosphere spiked in the 1950s and 1960s due to the testing of nuclear weapons during the Cold War.
When precipitation falls, it contains tritium from the atmosphere, but the isotope decays relatively quickly, with a half-life of about 12.3 years, meaning around half of it transforms into a form of helium every dozen years or so. By measuring how much tritium remains in a water sample and comparing that to the expected level when the liquid fell as precipitation, scientists can estimate the water’s age.
“It creates a very, very precise clock,” Brooks said.
Brooks and other researchers collected samples of water in the middle of winter, when the flows were low and stable, and the tritium analysis confirmed that this baseflow was derived from groundwater storage; its age averaged 10.4 years from the time it originally fell as rain or snow.
Then the scientists gathered water samples during spring and early summer, when the snowmelt was running off, and they found that the water averaged nearly six years old, meaning that groundwater was still making a major contribution to the overall streamflow.
Importance of underlying geology
Looking across the diverse sites, the researchers concluded that the underlying geology played a key role in determining the age of the runoff. The sites with younger baseflows were underlain by hard rock and shale, which are relatively impermeable, so groundwater contributed less to the flows. Sites with older baseflows were characterized by more porous rock, such as sedimentary layers, that allowed the water to infiltrate far more effectively.
“If you have a subsurface underlying geology that has very, very low permeability, there really isn’t any place for that water to be stored,” Brooks said. “If you have high permeability and higher porosity, it’s easier to get water in and there’s more places for water to store.”
These two drawings show conceptual models of how streamflow is generated in mountain watersheds. On the left, diagram a) shows the system common in many prevailing models of mountain hydrology, with shallow soils and bedrock only able to store limited water. On the right, diagram b) shows what the new paper suggests is actually happening: there is far more storage of water in bedrock and a relatively porous layer of weathered rock known as saprolite. Source: Brooks et al., 2025.
Soil moisture is another key factor that explains runoff patterns. But the authors note much more water is held in groundwater storage, and a focus on soil moisture in modeling is “also due to the fact that soils are relatively easy to measure and monitor compared to deeper groundwater.”
Brad Udall, a senior water and climate research scientist at Colorado State University’s Colorado Water Center, called the paper “eye-opening.”
“Paul and co-authors have done a really comprehensive look at a part of the water balance that heretofore has been mostly, completely understudied,” said Udall, who was not involved in the study. “It turns out this part of the water balance is looking to be more and more important in a changing climate world.”
With other studies highlighting the depletion of underground aquifers in the West, the paper’s focus on groundwater has “some pretty scary implications for future runoff in the Colorado and other Southwestern rivers,” Udall said.
“The Southwest’s water cycle has been flashing warning signs for 26 years . . . and this is just yet one more big warning to pay attention to,” he said, noting that much more research is needed on the West’s groundwater.
“What really . . . spooks me is there’s a delayed aspect of this,” Udall said. “If we’re looking at water that’s almost six years old, it means we may not see a problem until it’s six years too late, and that is particularly worrisome.”
Predicting streamflows
In Utah, Brooks said that accounting for groundwater storage has previously enabled his team to make more accurate predictions about runoff and flooding.
In 2021 and 2022, for example, Utah’s snowpack was around average, but Brooks said he and colleagues were able to correctly predict “horrendously low runoff” because they knew groundwater storage was meager. Similarly, in 2023, after a record snow year in Utah, the researchers accurately predicted only minor nuisance flooding because of the buffer of relatively low groundwater storage.
Water managers often look to April 1 snowpack readings as a barometer for the coming runoff season, but Brooks said gauging local groundwater storage in January or February can yield important insights about what’s to come in spring and summer.
“That simple number—how much groundwater is stored there relative to the long-term average—reduces your uncertainty in streamflow prediction by 50%,” Brooks said.
Measuring groundwater storage can be tricky, with nearby wells recording vastly different figures. “It’s really hard to get meaningful information on storage,” Brooks said.
However, the underlying geology across the West is widely understood from mapping and can be used to approximate whether an area has the potential to store more or less groundwater.
The researchers also argue that water managers can get a better handle on streamflows by employing tritium sampling themselves during the winter and the snowmelt season.
Brooks said he hopes the findings can be incorporated into hydrologic modeling and runoff predictions, but significant cutbacks in the federal workforce mean “it’s a very challenging time for water resource managers.”
“In an ideal world, we would have a National Science Foundation or NOAA or a private foundation say, ‘Hey, this could be really important. If we can predict streamflow more efficiently and earlier, we can make better decisions about how to manage it.’”
Streams like this one in the San Juan National Forest near Silverton, Colorado, on August 2, 2025, help supply residents, businesses, farms, ecosystems and other water users downstream. Video by Mitch Tobin/The Water Desk.
