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When the West’s rivers surge each spring, older groundwater dominates the runoff

By
Mitch Tobin
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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. 

With wildfire-prevention work, Flagstaff seeks to avoid the next devastating flood

By
Brett Walton, Circle of Blue
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A detention basin under construction in Flagstaff, Ariz., will store excess water coming from Spruce Wash, an area that flooded in 2021 after the Museum Fire. (Brett Walton/Circle of Blue)

FLAGSTAFF, Ariz. – Five large wildfires have burned tens of thousands of acres in the forests around this northern Arizona city in the last 15 years. Monsoon floods after those fires closed roads, wrecked homes, and took the life of a 12-year-old girl. 

But it is the fire that has yet to burn that most worries City of Flagstaff and Coconino County leaders. 

A large blaze in the Upper Rio de Flag watershed, which crosses the heart of the city, would be a deep wound. If it were coupled with intense monsoon rains, a fire that burned the entire 21,500-acre basin could trigger a flood catastrophe. 

In a worst-case scenario, the fire-flood combo could cause at least $2.8 billion dollars in economic losses, according to a 2023 assessment from Northern Arizona University’s Economic Policy Institute. Those estimates, which are conservative, include property damage, fire suppression, illness, loss of business revenue, and repair costs. They do not account for potentially expensive impairments to a major BNSF railway and Interstate 40 or effects on Grand Canyon tourism or multiple storms. Even a smaller fire that burns only 15 percent of the watershed could carry a $535 million price tag.

“If that watershed really burns, Flagstaff is in a world of hurt,” said Joe Loverich, who worked on the flood models that supported the economic analysis.

A disastrous outcome, however, is not preordained. With the right mix of data-informed foresight, proactive measures to reduce fuel loads by thinning dense stands of ponderosa pines, and luck, city and county officials hope to avoid the severe wildfire that would wreck the watershed and trigger the dreaded cascade of flood and debris. The risk cannot be eliminated. But it can be estimated. And it can be reduced.

The condition of western U.S. forests has climbed to a matter of national importance as megafires churn through millions of acres annually. The U.S. Forest Service has developed a wildfire strategy to protect critical infrastructure, wildlife habitat, recreation areas, communities, and headwater streams that are the source of drinking water for tens of millions of people. In that strategy, the Flagstaff area was designated a high-risk landscape. At the same time, the Trump administration is promoting logging as risk reduction while also cutting federal programs that help communities prepare for climate hazards.

Though the federal government is experiencing the whiplash of new administration priorities, durable, collaborative models to dampen the risks of severe wildfire and post-wildfire flooding still exist. In the last 15 years, Flagstaff and Coconino County have emerged as leaders in developing these strategies. They are joined in this watershed-focused work by organizations like Denver Water, Rio Grande Water Fund, and Placer County Water Agency. 

The playbook developed in Flagstaff includes financial models to fund forest thinning and risk models to inform decision-making. Converting knowledge and money into projects on the ground requires partnerships that extend across local and federal agencies to connect with the private sector and NGOs. And it involves physical restoration of the landscape, both before and after a fire, so that fires are less destructive and floodwaters less perilous.

“The numbers are so clear,” said Lucinda Andreani, administrator of the Coconino County Flood Control District. “You spend so much money post-wildfire and you lose key assets and you lose communities that I think people are more and more understanding that we’ve got to keep investing in forest restoration.”

As more of the American West burns, Flagstaff’s experience is akin to a cairn in the wilderness, a waypoint showing where the rest of the region is heading.

Understanding Risk

As with most public policy shifts, the reckoning in Flagstaff and Coconino County was borne from calamity.

Post-fire flood risk came to the fore after the Schultz Fire, in 2010. Burning about 15,000 acres along the San Francisco Peaks, it was the first large fire near the city in more than three decades. 

The fire damage was compounded by subsequent downpours. This area of the Southwest is subjected to stacked hazards: a fire season that overlaps with monsoon season. These punchy rainstorms are short-lived but potent. They can dump several inches in an hour or less. When they occur over a burn scar, which was the case after the Schultz Fire, 20 to 30 times more water can be flushed down a stream channel. If an area is burned again – the 2022 Pipeline Fire, for instance, reburned parts of the Schultz scar – the watershed is even more vulnerable to floods and erosion. 

The Pipeline Fire burned in Coconino National Forest in 2022. City of Flagstaff and Coconino County officials hope to avoid a similar severe fire in the Rio de Flag watershed. (Brett Walton/Circle of Blue)

After the Schultz Fire and subsequent floods, Coconino County received a FEMA grant to conduct a countywide assessment for flood and debris risk. JE Fuller, a firm that analyzes landscape hazards in the Southwest, was hired to do the modeling work. In the model, “we basically burned everything,” said Joe Loverich, a project manager at the firm. Then Loverich and his colleagues looked at where debris and water flows would do the most economic damage.

Society has been constructed as layers of fixed assets – roads, bridges, houses, water supply pipes, wastewater treatment plants, landfills – atop a landscape that flexes more than we’d like. When the environment changes, the risk to these assets also changes, Loverich said.

That happens after a severe wildfire, which transforms a watershed into something more dangerous. It shakes society’s physical foundation, not just for weeks but for years. The landscape becomes threatening in a way that it wasn’t before.

“We’re developing the science of understanding what the risk is,” Loverich said. “What it is, who it affects, why you should be concerned about it. And what that can do is then lead to an understanding of what we should do about it.” 

In JE Fuller’s model several areas of Coconino County stood out as particularly susceptible to post-wildfire landscape transformations. One was Williams, a town some 30 miles west of Flagstaff. Williams has two water supply reservoirs that could be inundated with debris from post-fire floods originating in the Bill Williams watershed above town. In this flood scenario, the reservoirs could be rendered inoperable until they were dredged. The water supply would be cut off. Downtown Williams, meanwhile, could see “a wall of six feet of water,” Andreani said.

Other high-risk areas are clustered around the Upper Rio de Flag watershed, which crosses Flagstaff from north to south before turning eastward. 

Responding to Risk

Most of the year, the Rio de Flag is a dry, narrow channel. Only rainfall and snowmelt give it life. On a July day earlier this summer, the section through Thorpe Park, near the city center, was covered in seasonal grasses and brush that hid subsurface drainage structures installed as part of a $122 million Army Corps flood-control project.

The relative calm of a dry channel could be disrupted if the right combination of fire and rain were to hit higher in the watershed.

Some of those punches have already landed in the Flagstaff area. The Schultz Fire, which caused some $100 million in damages, was the first caution sign.

More warnings came later. The Museum Fire, in 2019, burned only about 2,000 acres. But the fire occurred upstream of one of the areas identified as a high flood risk in the countywide modeling assessment. Two years later, ferocious monsoon rains swept through the area and caused substantial flooding in the Sunnyside neighborhood along Spruce Wash, a Rio de Flag tributary. Today, work crews are in the midst of a $26 million project to expand flood channels and retention basins in the neighborhood.

The San Francisco Peaks rise above the Rio de Flag, which crosses the center of Flagstaff, Ariz. A severe fire in the upper watershed would increase flood risk in the city. (Brett Walton/Circle of Blue)

Knowing these potential outcomes, how is a place like Flagstaff to react? The city decided to ask its residents to pay for fire-risk reduction efforts that would take place on national forest land. 

Flagstaff residents understood the need. In 2012, city voters approved a $10 million bond proposal to fund the Flagstaff Watershed Protection Project, one of the first such efforts in the country. 

Cal Joyner, former Southwestern regional forester for the U.S. Forest Service, called the bond’s passage “a great example of civic environmentalism” that led to a close partnership between the Forest Service and the city.

More funding and collaborations would follow. The Four Forests Restoration Initiative, a project to reduce catastrophic fire risk on 2.4 million acres of national forests in northern Arizona, contributed money and led an environmental assessment that cleared the path for large-scale thinning and prescribed fire projects across the project’s footprint. The state stepped in to facilitate development of a timber mill that could make use of the small-diameter trees that were being cut. 

In 2020, Flagstaff increased its contribution by levying a Water Resources and Infrastructure Protection Fee on water bills. The fee of 52 cents per 1,000 gallons (now increased to 53 cents) helps to fund fire mitigation projects in upstream forests. In 2022, voters approved a $26 million bond for the Spruce Wash repairs. Three months later the City Council voted to increase stormwater fees by 12% annually for six years to pay for flood-control infrastructure and maintenance.

“There’s no one organization or municipality or county or anybody that can do all of this by themselves,” said Neil Chapman, wildland fire captain for Flagstaff Fire Department. “And so, partnerships are the way we scale up.”

All told, a mix of public agencies, private firms, and NGOs are raising funds, assessing risks, using computer models to test and refine their designs, and ultimately restoring forests. 

“Having efficient organization at the local level to leverage the federal money and the state money that’s available is really key,” Loverich said. “And that’s something the City of Flagstaff and Coconino County have been really good at.”

Just last month the Coconino County Flood Control District partnered with The Nature Conservancy and Coconino National Forest to begin work on a 2,045-acre tree thinning project in the Upper Rio de Flag. The district contributed $2 million while the national forest chipped in $2.5 million.

Investing in Forests

Fire will occur in these high-elevation southwestern forests. The ecosystem has evolved that way. The aim for city and county officials is to prevent the high-intensity, catastrophic blazes that cook the soil and transform the watershed into a high-hazard flood risk.

Reconstruction work after a massive flood, as Andreani knows, is expensive. Some $130 million is being spent on flood-control projects after the Pipeline Fire, which occurred in 2022 and reburned portions of the Schultz Fire. The reconstruction there is a two-part strategy: repair and expand alluvial fans on national forest land. These slow down water and trap sediment and debris. Then, in the neighborhoods, build pipes and culverts to direct water away from homes, roads, and other high-value infrastructure.

That steep cost is why preventative work in the forests is so important, Andreani said. Things like restoring alluvial fans and cutting smaller trees or setting small, low-intensity fires to reduce forest fuel loads.

Though these measures can save money in the long-run, thoughtful action on the front end is not as highly valued. The Coconino County Flood Control District has identified an area in the Upper Rio de Flag that has eroded and could be proactively restored. Rejected for one federal grant, the district is still seeking funds to do the mitigation work. 

“I’ll tell you it’s a lot harder to get that money than it is to get the disaster money,” Andreani said.

What money is available for preventative work should go toward forest restoration and forest thinning, Andreani and others said. That provides the most value per dollar. But translating that into a reliable funding stream to match the scale of the problem remains a challenge.

“There are so many benefits that come out of the forest,” Andreani said. They provide water, carbon storage, recreation, and habitat for endangered species. Though Flagstaff is at the forefront of using creative financing to fund forest restoration work, in general the opportunities are limited. 

“How do people contribute to this work?” Andreani added. “If you put that across the millions of electric ratepayers, water ratepayers, recreationists, I mean, you add up all the different economic benefits that come from having a healthy forest. I frankly think there’s a lot of money, but we haven’t got the mechanisms in place.”

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.

As flames scorch western forests, Flagstaff area offers roadmap for post-wildfire flood prevention

By
Brett Walton, Circle of Blue
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Ivan Pacheco stands next to the flood-control system that was built in his family’s backyard following the Pipeline Fire. (Brett Walton/Circle of Blue)

FLAGSTAFF, Ariz. – In July 2022, for the second time in a month, the landscape above the Wupatki Trails neighborhood took a beating. 

The first blow was the Pipeline Fire, which ignited on June 12, 2022, and burned 26,770 acres mostly in Coconino National Forest including the slopes above Wupatki Trails and eight other forested drainages flowing into residential areas of Coconino County a few miles north of Flagstaff.

Danny Cobb, who had moved to the high desert of northern Arizona six months earlier from Anchorage, captured video of towering smoke plumes as he evacuated with his family. Ivan and Christy Pacheco, who live down the block, left as well. 

Both families returned to the neighborhood with a feeling of relief. Their homes were still standing.

But then, weeks later, the second disruption in the forest occurred – borne not of fire but of water.

The southwest monsoon is an annual feature of Arizona weather. In the summer months, the punchy precipitation pattern delivers short, drenching cloudbursts – as much as several inches of rain in an hour. In Coconino County, the summer 2022 monsoon was a conveyor belt of destruction. A series of storms inflicted wave upon wave of property and infrastructure damage downstream of the Pipeline Fire burn scar. Lucinda Andreani, administrator of the Coconino County Flood Control District, counted 45 major flood events that summer that closed roads and flooded properties.

The summer storms whisked water off slopes and soils now charred by the fire. They flooded U.S. Route 89, a main highway heading north, some 13 times. They carved deep channels in the land, transported huge volumes of sediment, and pummeled homes with boulders larger than basketballs.

Christy Pacheco, a kayaker, called the murky torrent moving through their backyard a “class eight” whitewater. The top of the scale for Grand Canyon rapids is 10. “It was pretty powerful,” she said. The Pachecos stacked four layers of sandbags atop a berm on their property. When that wall started to fail, they grabbed wood panels and other supplies from their garage to act as makeshift levees.

“We were within half an inch of having all that mud and water coming in the house,” Ivan said.

A landscape coming apart at the seams that summer became the principal challenge for Andreani, other Coconino County and City of Flagstaff officials, and their long-time watershed restoration collaborators in the private sector. In the frantic months after the fire, they had a single, unifying mission that would shape the next year of their professional lives and become a $130 million endeavor:

Fix the watershed before it breaks again.

The disaster after the disaster

The western United States is experiencing an era of wildfire. From the ponderosa pine forests of Arizona and Colorado to the chaparral of Los Angeles County, wildfires are burning more acres with greater intensity. Recent research indicates their growth rate has accelerated, spreading flames with worrisome speed. 

The shift is happening for several reasons. The region’s forests, owing partly to the U.S. Forest Service’s 20th century policy of fire suppression, are artificially crowded with kindling. A warming climate due to the accumulation of heat-trapping gases in the atmosphere is roasting the landscape and drawing moisture out of its vegetation. Bark beetles have killed or wounded tens of millions of acres of timber. The result is dense forests riven with dead and drying plants that are primed to burn.

Wildfire damage is immediate and obvious. Denuded forests, noxious smoke that drifts across continents, destroyed homes, lives lost.

The Pipeline Fire burned in Coconino National Forest in 2022. (Brett Walton/Circle of Blue)

What Flagstaff and many western U.S. communities are also struggling with is the long reach of a wildfire, the slow disaster that expresses itself months, years or even decades after the flames are extinguished. The recovery in Flagstaff is instructive – a testament to the risks of an altered landscape, the coalition-building and public outreach required to address them, and the high cost of reconstruction.

The deadliest and most destructive of these post-wildfire hazards are the floods, landslides, and debris flows that are wrought by water. The hazards are particularly acute in the monsoon-influenced regions of the Southwest.

Last month in Ruidoso, New Mexico, the monsoon deposited several inches of rain over an area that burned the previous year in the South Fork and Salt fires. The Rio Ruidoso swelled five feet higher than its former record peak, killing three people.

Important infrastructure threads through these forests and watersheds. It is often in harm’s way. The Ruidoso flood hobbled the town’s wastewater system. In Washington state, the Yakima-Tieton Irrigation Canal was punctured by debris flows after the Retreat Fire last August. The irrigation district that operates the canal is seeking a $240 million replacement for a leaking water-delivery structure that serves 35,000 acres of mostly orchards.

The Hermit’s Peak-Calf Canyon Fire, in 2022, inflicted so much injury on the Gallinas River watershed that Congress granted Las Vegas, New Mexico, $140 million for a new water treatment plant to filter higher levels of sediment in its drinking water source. As more acres succumb to wildfire, the U.S. Forest Service expects one-third of western U.S. watersheds to experience a doubling of post-fire sediment flows in rivers by mid-century.

Even in Flagstaff such assets have required emergency repair. The Inner Basin pipeline, one of several city water sources, can fulfill as much as 20 percent of summer demand, said Brian Huntzinger, the water production manager for Flagstaff. After monsoon floods following the Pipeline Fire, the water supply pipeline was cracked in three places by debris and rocks, he said. The $16 million repair project included stabilizing some 45 sites where the structure crosses drainages.

“When you have rain occur on top of a burn scar,” Huntzinger said, “you have these just devastating floods where the whole slopes of a mountainside, these drainages, everything comes down the mountain because there’s nothing to hold that soil in.”

Assemble the team

In the aftermath of the Pipeline Fire, Coconino County embarked on an ambitious plan to hold in that soil and protect – within reasonable limits – the safety of the public works and roughly 1,500 private properties downstream of the burn scar.

The plan’s outline – a mix of natural and concrete systems – was relatively simple in concept. The ideas about stream channel restoration had been developed in Colorado by the hydrologist Dave Rosgen and proven in Coconino County in response to previous fires. But the restoration and engineering work required after the Pipeline Fire had not been deployed at such scale across so many watersheds, Andreani said.

The first objective was to retain as much soil and sediment on the forested uplands as possible. This would be done by repairing drainage channels that had been scoured into deep gullies. Then, in tandem, calm fast-moving water and spread it out across the landscape. Finally, down in the neighborhoods and along the highway, use hard infrastructure like pipes, culverts, and channels to direct the now-diminished flows away from homes, roads, and the local landfill.

Andreani knew who to call. By this time, Flagstaff and Coconino County had already been through watershed restoration and flood-control work after the Schultz Fire, in 2010, and the Museum Fire, in 2019. Like the Avengers in the Marvel movies, Andreani had people in place with expertise and experience. This restoration project would be her team’s “third rodeo.” It would be the largest yet.

JE Fuller, an engineering company, would do the flood modeling. One of its employees was drafted as part of the U.S. Forest Service team evaluating the fire’s burn severity. Natural Channel Design Engineering, a Flagstaff-based firm, would sketch the watershed repairs. These treatments would be carried out on Forest Service land with the goal of protecting assets downstream. Civiltec Engineering would contribute the engineering work within the neighborhoods. Tiffany Construction, a contractor, would move the earth. 

Andreani, meanwhile, was in contact with congressional representatives and local, state, and federal agencies to drum up financial support. The county needed outside money to cover a price tag that would rise into the low nine figures.

“If you’ve never been through it, you get so wrapped up like we did in just trying to figure out how to mitigate impacts to people’s homes, right?” Andreani said about flood hazards in the weeks and months after a wildfire. “So people have somewhere to go home at night, and they can at least try to get some sleep.” But funding is the grease that turns the wheel. “And so I just said, ‘No, we’re going to really hit the ground running. We’re going to make this ask.’”

The windfall that Andreani sought came through in December 2022 in the form of a congressional appropriation totaling about $100 million in an omnibus spending bill. About $30 million from other state and federal sources would trickle in later. But the major restoration work in the nine drainages could begin.

Slow it down, spread it out

The Pipeline Fire is one of several wildfires – including the Schultz Fire – that have remade the forests and watersheds northeast of Flagstaff in the last 15 years.

Before Schultz, the watersheds were “complacent,” to use a hydrology term. Rainfall did not produce much runoff. The water soaked into the ground. Allen Haden, an aquatic ecologist with Natural Channel Design, pulled up satellite photos from 1985 of the east side of the San Francisco Peaks, where the Pipeline and Schultz fires burned. No big channels are visible.

Allen Haden of Natural Channel Design Engineering stands next to a restored alluvial fan in Coconino National Forest, where the Pipeline Fire burned in 2022. Haden was part of the team that designed the post-fire watershed restoration. (Brett Walton/Circle of Blue)

The Pachecos felt this, even if they didn’t notice it when they moved to Wupatki Trails in 2005. Not living in a valley or near a river, “we didn’t even think about flooding as an issue,” Ivan said.

After the Schultz Fire, the watershed was transformed, Haden said. “That complacency is eradicated overnight.”

The fire burned so hot in places that it cooked the soil, changing its chemical properties. “Once that happens, it becomes like a parking lot,” said Haden, who helped design the watershed repairs after the Pipeline Fire. These hydrophobic soils are common after severe fires in ponderosa pine forests like those around Flagstaff, he said. 

The parking-lot effect showed up downstream. Peak stream flows after the Pipeline Fire increased 20-fold in some drainages. High-volume, fast-moving flows bite into the channels, eroding them and producing a firehose of sediment that moves downstream. “Once the gully process starts, things fall apart,” Haden said.

The goal of the restoration work was to reintroduce laziness to the watershed. That would be accomplished primarily using alluvial fans. These are natural features in stream channels, composed of loose sediment and rock. Though they look like a field of rubble, the post-Pipeline Fire fans were highly engineered for specific slopes and depths, Andreani said. Some of the reconstructed fans are massive, the largest measuring 40 acres. Nine fans were restored or expanded and 10 new ones were built. They are the first line of flood defense, intended to trap larger materials washing down the forest slopes and blunt the speed of the water.

Without the fans, any hard infrastructure within the residential areas would fill with sediment and be rendered useless, Andreani said. Not just immediately, but repeatedly. “In these burn areas, the debris and sediment doesn’t go away. It’s going to take decades.”

While the fan restoration work was happening, construction crews were working in the neighborhoods and within the Route 89 corridor to install channels and culverts. A 10-foot diameter pipe was placed in a tunnel bored beneath the highway. On Campbell Avenue homes were connected to the road by tiny bridges across a flood channel.

Constructing the neighborhood drainage structures was an exercise in patience. County officials and their partners held meetings and went door to door to secure easements from homeowners in the nine watersheds to build across their land, if necessary. Computer modeling was done to show that installing an engineered structure would not flood any home more than it would have flooded without the project. 

The restoration work, broadly speaking, was intended to protect homes from two inches of rain in 45 minutes, an event that has a 4% chance of occurring each year. The modeling was conservative, though. And the alluvial fans, which are difficult to incorporate into the flood models, seem to be doing a better job than expected. 

“We don’t over promise,” Andreani said. “But we see almost every system performs beyond what the modeling tells us it will do. And it’s because of those on-forest measures, the fan restorations in particular.”

An immediate test

Of the nine watersheds that were restored after the Pipeline Fire, some of the most creative problem solving took place in Wupatki Trails, Haden said. A single channel would not be enough to handle the expected flows. Instead, they converted an existing vegetated channel into a concrete structure that could withstand higher stresses and more water. They then split the flows coming from the tail of an expanded alluvial fan upslope of the houses. Water would go two directions around the neighborhood.

An engineered channel along Campbell Avenue, in Coconino County stands ready to receive flood waters. The San Francisco Peaks, where the Pipeline Fire burned in 2022, rise behind the channel. (Brett Walton/Circle of Blue)

The contractors finished their work in Wupatki Trails in July 2023, just 12 months after the fire. And not a moment too soon. The flood-control work was put to an immediate test. 

The next day a monsoon storm dumped roughly three inches on the slopes above Wupatki Trails, equivalent to a 100-year storm. Would the fix hold? Neighbors gathered anxiously on the banks of the engineered channel. Resident Danny Cobb recorded video of the water hurtling by. But it did not overtop.

Cobb’s property is near the spot where the channel splits. “It’s nothing short of amazing,” Cobb said about the flood-control work in the forest and neighborhood. “To have help within a year – that’s big.”

Down the block Ivan and Christy Pacheco also see the benefits. They gave up a small corner of their property for a drainage pipe. In return, the county added a berm to their backyard and regraded a four-foot-deep fissure that had been gouged by floods the previous summer.

Though the flood-control work has held so far, it has limits. The interventions likely cannot protect homeowners from the biggest floods, those generated by more than three inches of rain in an hour. Even as a warming planet is producing larger cloudbursts, engineers must work within the constraints of cost and existing infrastructure. 

“You only have so much room,” Haden said.

Christy Pacheco recognizes that flood risk, though substantially reduced, is still present. The family’s horse that used to roam the backyard remains in Colorado, where it was sent after the fire.

“I still do not feel 100 percent safe,” she said.

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.

The Water Desk supports journalists covering the Colorado River Basin

By
The Water Desk
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The Water Desk is excited to announce the recipients of new grants to support water journalism connected to the Colorado River Basin.

The grantees will be reporting on a range of critical water issues facing the region, including climate change, biodiversity, pollution, groundwater, ecological restoration, water conservation, tribal water issues and more.

The nine awards, up to $10,000 each, are being funded thanks to the support of the Walton Family Foundation. A total of $70,900 has been awarded in this round of grantmaking.

The recipients of The Water Desk’s 2025 Colorado River grants (in alphabetical order):

  • Melissa Bailey, independent
  • David Condos, KUER
  • Jonathan Goodman, independent
  • Ian James, Los Angeles Times
  • Elizabeth Miller, independent
  • Jim Robbins and Ted Wood, independent
  • RJ Sangosti, The Denver Post
  • Debra Utacia Krol, The Arizona Republic/azcentral
  • Janet Wilson, The Desert Sun

The Water Desk maintains strict editorial independence from its funders and the University of Colorado. Funders of The Water Desk have no right to review or to otherwise influence stories or other journalistic content that is produced with the support of these grants. For more about our editorial independence, please see our funding page.

Congratulations and best of luck to our grantees. We look forward to seeing the water journalism they produce!

Indigenous youths finish historic journey down Klamath River after dams removed

By
Eleanor Bennett, Aspen Journalism & Aspen Public Radio
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Indigenous youths with Ríos to Rivers’ Paddle Tribal Waters program head toward the shore where the Klamath River meets the Pacific Ocean in Northern California on July 11. The young kayakers were joined by a flotilla with dozens of tribe and community members on the final days of their monthlong, 310-mile journey. (Erik Boomer / Courtesy of Ríos to Rivers)
Eleanor Bennett reports for Aspen Journalism and Aspen Public Radio

KLAMATH, Calif. — In a thick forest along the remote northern California coast earlier this month, a group of mostly young Indigenous kayakers pushed off into the clear-emerald waters of the recently undammed Klamath River. 

The 13- to 20-year-olds from more than six tribes in the Klamath Basin, along with several instructors, had been paddling for a month, covering over 300 miles. 

In just a few hours, they would reach the Pacific Ocean, making the group among the first in over a century to descend the river from its headwaters in southern Oregon to its mouth in northern California. The expedition began in early June after the largest dam-removal project in history was completed last fall to restore salmon populations, improve water quality and support tribe-managed lands. 

In the group was 15-year-old Hoopa Valley tribe member Carmen Ferris, who comes from a long line of fishing people along California’s Trinity River. 

“The Trinity is the biggest tributary to the Klamath,” she said. “So I feel like I have a deep connection and ancestry with both of the waters.”

Carmen and about 40 other Indigenous kayakers had spent years training for the expedition with the help of Ríos to Rivers. Founded by Aspen resident Weston Boyles, 38, the nonprofit organization works with Indigenous youths around the world to protect rivers through advocacy, education and exchange programs. 

Thirteen-year-old Scarlett Schroeder, left, and Coley Miller, 14, who belong to tribes on the Upper Klamath, stand with their paddles on the banks of the Klamath River. The Paddle Tribal Waters group of 13- to 20-year-olds from more than six tribes in the Klamath Basin, along with several instructors, were among the first in a century to paddle the free-flowing river after several major hydropower dams were removed last year. (Erik Boomer / Courtesy of Ríos to Rivers)

Historic paddle

In anticipation of the removal of four of the Klamath’s six dams, Boyles teamed up with local Indigenous youths and kayak instructors to launch the Paddle Tribal Waters program, with the goal of supporting young tribal members aiming to be the first to paddle the mostly free-flowing river since the first dam was built in 1918. 

Although Carmen had heard about the dams growing up, it wasn’t until joining the program that she learned the full history of the decades-long effort by tribes and environmentalists, including her own Hoopa Valley people, to remove the dams from the Klamath and restore the salmon that local tribes once depended on. 

“I was like, ‘Oh, my God, that is happening, and it’s nearby,’” she said. “I was in shock, and I learned about the history and what my ancestors and people before me have gone through for these dams to finally come out.” 

Carmen spent two years in the Paddle Tribal Waters program — taking tribe-led classes on river ecosystems, advocacy and cultural knowledge, as well as learning to whitewater kayak both in her own backyard and on exchange trips to Chile. 

“I built a love for kayaking,” she said. “And then I was like, I’m definitely doing the descent, like I can’t stop kayaking now.” 

The journey from the river’s headwaters to the Pacific Ocean wasn’t easy, from camping in a remote, rugged wilderness to tackling a number of Class 4 rapids on the upper Klamath, including one called “Big Ikes.”

“I got battered into this hole for a little bit, and if I didn’t know how to roll, I’d probably swim that day, which wouldn’t have been fun, because there were a lot of rocks,” she said. “I ended up being OK, but everyone was like, ‘Carmen, what happened?’”

Ruby Rain Williams of the Karuk tribe, who turned 18 on the trip, said the paddle group faced other challenges beyond navigating technical and dangerous rapids. 

“There were definitely some hard parts, like getting up every morning around 6:30, and also the flat-water days on the lake with the headwind were quite treacherous,” Ruby said. 

They also learned some valuable river-trip lessons, including the importance of sun protection. 

“I remember the first couple days, we’re all like, ‘Oh, we don’t need sunscreen. We never wear sunscreen,’” Ruby said. “You know, we’re swimming in the river all day and I put pink Zinc on my face just to look cool and I had polka dots burned all over my cheeks and my ears were burnt, and even my eyes because I didn’t wear sunglasses. It was just gnarly.” 

A map of the Klamath River Basin shows the four hydroelectric dams that were removed last year: Iron Gate, Copco 1, Copco 2, and J.C. Boyle. The two remaining dams in the upper river basin (located west and northwest of J.C. Boyle Dam and depicted as gray dots) are mostly used for farming irrigation. (Courtesy of Cal Poly Humboldt)

Reshaped landscape 

Along the river, the young kayakers saw how the dam removal and restoration effort had started reshaping landscapes and communities as they paddled through former reservoirs and dam sites, including Northern California’s Kikacéki Canyon, where for decades the water had been diverted to a power station, leaving a dry stretch of riverbed. 

The four recently removed hydropower dams, which were built between 1918 and the mid-1960s, were still producing relatively low amounts of electricity. According to PacifiCorp, which operated the dams and is owned by Warren Buffett’s company Berkshire Hathaway, the sites were producing less than 2% of the operator’s total power generation — enough to power about 70,000 homes when they were running at full capacity.

The recently undammed Klamath River runs through the site of the former Copco Lake reservoir, named for the Copco 1 dam, in Northern California. Restoration efforts have begun above the former dam site, but signs of the former reservoir still remain on the landscape. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

In addition to losing a relatively low amount of power generation, there were other concerns about removing the dams. These included potential impacts of drained reservoirs such as exposed sacred burial sites that had been previously submerged, increased fire risk, loss of tax revenues for nearby counties, and decreased property values for former lakeside homes. 

Still, scientists and advocates for dam removal maintained that the dams and their reservoirs worsened water quality in the river and that removing them would reduce the likelihood of sediment buildup, toxic algae blooms and diseases that thrive in warmer, stagnant waters and are harmful to salmon. They also maintained that the dams blocked salmon from returning to their upstream habitat where fish lay eggs and babies grow before migrating to the ocean. 

Eventually, local tribes and other dam-removal advocates came to an agreement with PacifiCorp and federal regulators, and in 2022, the four dams on the lower Klamath were approved for removal. 

In order to alleviate some of the community concerns, the Klamath River Renewal Corporation (KRRC), which helped broker the dam-removal deal, and Resource Environmental Solutions (RES) are now overseeing restoration efforts. These include working with fire officials concerned about the loss of a wildfire-fighting resource once the reservoirs were drained to set up dry-hydrant systems that allow crews to pull water directly from the river. 

They also worked with the Shasta Indian Nation to mitigate the risk of damage to newly exposed cultural sites. Last year, the state of California also transferred some of the land near one of the former reservoirs back to the group. 

Other restoration projects include excavating sediment that had built up behind the dams and planting billions of native seeds along the riverbanks and former reservoir sites. 

The two dams that remain in the upper section of the river in southern Oregon are primarily used to divert water for irrigation and farming. During their monthlong river trip, which began in Chiloquin, Oregon, the Paddle Tribal Waters group carried their kayaks on land and portaged around these remaining dams.

Tribal Paddle Waters youths kayak below the Keno dam, one of the two remaining dams on the upper Klamath. The expedition group carried their kayaks on land and portaged around both of the remaining dams. (Erik Boomer / Courtesy of Ríos to Rivers)

Salmon returning

Brook Thompson, a scientist and Yurok and Karuk tribe member, researches salmon life cycles and water quality, and joined the paddlers for the last few days on the river. 

Despite an unexpected salmon die-off after the first of four dams came down last year, Thompson said hundreds of miles of fish habitat on the Klamath and its tributaries have now opened up and dwindling salmon populations are already returning to spawn in greater numbers.

“We really did not know what was going to happen with the salmon and if they would return right away, or if it would take years,” Thompson said. “So the fact that they immediately started going past where the dam sites were is so exciting for me as a tribal member.”

Researchers have also found lower rates of disease-carrying parasites and toxic algae since the dams were removed last year, according to Thompson. 

Young Indigenous kayakers lead a flotilla of rafts and canoes on the final stretch of the Klamath River before reaching the Pacific Ocean on July 11. The 310-mile journey marked the end of a decades-long effort by tribes, environmentalists and fisher people to remove four major dams on the river in order to restore salmon habitat, improve water quality and support tribe-managed lands. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

Thompson decided to study environmental engineering, water infrastructure and ecosystems after tens of thousands of dead salmon clogged the lower reaches of the river during a major drought in 2002, after a decision by the Bush administration that reversed environmental protections and allowed upper Klamath farmers to divert much of the remaining water.

“Witnessing thousands of fish die on the river firsthand as a 7-year-old really devastated me, personally, because these salmon are not just a food source for my family, they weren’t just our income — I paid for all my school clothes and supplies through selling fish as a kid — but they’re also a connection to family, they’re my connection to my ancestors and they’re really the lifeblood of the tribes here,” Thompson said.

Now that the dams are out, Thompson hopes reconnecting with the river, including through salmon fishing and recreation opportunities, can help address a rise in health concerns such as cardiovascular disease and diabetes, as well as mental health challenges faced by tribes in the region, including addiction and suicide.

“When you lose out on that culture, you’re having all these issues health-wise, and you’re having people die because of it,” Thompson said. “I know for me, if I’m not by the river, and I don’t get a chance to fish and pray and be thankful for this food that feeds my body, that connects me to my ancestors, then I don’t feel as well mentally either.”

Although the Klamath was once the third-largest salmon-producing river on the West Coast, young people such as Ruby, the Karuk tribe member, had only heard stories about those days. 

Carmen Ferris, in the red kayak, of the Hoopa Valley tribe, and Ruby Rain Williams, in the blue kayak, of the Karuk tribe, float on a peaceful stretch of the Klamath River the day before reaching the Pacific Ocean. The two young paddlers grew up hearing stories from their elders about a time when the undammed river was plentiful with salmon. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

“My grandma and my dad always told me how there used to be so many salmon in the river, you used to be able to walk across their backs and almost make it across,” Ruby said. “There was such an abundance of them that my grandpa would go spearfishing and be able to see them swimming through the river, because it was so clean and healthy.” 

During a fall scouting trip before their monthlong journey, Ruby and another young kayaker were some of the first to witness the salmon migrate past one of the former dam sites in Kikacéki Canyon. 

“We looked down, and then there’s these salmon just flying up the river, and you could see their heads at the top of the river’s edge,” Ruby said. “I’ve never seen that before. And to be able to say that I saw some of the first set of salmon make it up above where the dams used to be was incredible.”

‘Only the beginning’

John Acuna, a Hoopa Valley tribe member and Ríos to Rivers kayak instructor, helped lead the group of young people on the Klamath just a few years after being introduced to the sport. 

Despite nearing the end of a long expedition with only a day left on the river, Acuna sees the monthlong descent as the beginning of something bigger. 

“This is the biggest dam removal in history, and kind of the question is ‘What do we do next?’” Acuna said. “The hope is that this sets a precedent for other dam-impacted rivers and dam-threatened rivers, and I think our work has kind of just begun.” 

Young kayakers with Paddle Tribal Waters embrace a loved one on the beach July 11 after completing a 310-mile journey to the Pacific Ocean. Community members welcomed the paddlers home with a traditional prayer ceremony on the beach. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

Ríos to Rivers board member and river guide Jaren Roberson, who grew up in Arizona, agrees — and he hopes the recent dam-removal can be a model for how his own Diné (Navajo) and Hopi tribes can have a greater say in how water is allocated in the Colorado River basin. 

“Indigenous people should be figures in these resource management areas because they’re the ones who have been taking care of them and have been living in these places for generations and generations and generations,” Roberson said. 

During the last few days of the trip, Boyles, Ríos to Rivers’ founder, invited Indigenous groups from Bolivia, Chile and New Zealand to join a flotilla with dozens of local tribe and community members, which accompanied the long-distance paddlers as they neared the end of their journey. 

Paddle Tribal Waters youths run to touch the ocean at the mouth of the Klamath River aft9er finishing their monthlong journey July 11. Some of the young paddlers have already started their own kayak clubs in their communities to help other Indigenous youth reclaim their rivers. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

Afterward, the visitors were invited to share their experiences with dams in their own communities during a two-day symposium on the Yurok Reservation, near the California towns of Requa and Klamath, where the river meets the ocean. 

“In other basins, the mistakes of building dams, of destroying habitat, destroying culture, can be avoided if we learn from the past,” Boyles said, addressing the symposium crowd July 12. “And that’s a goal and a vision of ours, is to make sure that folks in river basins that have yet to be impacted or could avoid having the big impacts of dams, can come here to the Klamath and other parts of the world and learn from all of your lived experiences.”

Reaching the ocean 

On July 11, the final day of the monthlong paddle, dozens of community members lined the beach and cheered as the flotilla, with the young kayakers leading the way, emerged from the mist and paddled toward the Pacific Ocean. 

Clarence Hostler, of the Hoopa Valley, Yurok and Karuk tribes, and two younger men brought traditional drums to welcome the paddlers. 

He grew up swimming on the river as a kid in the 1950s, but he had to stop after he got a rash from the toxic algae. 

“So I hadn’t been on the water on the Klamath since 1965, and just a couple of days ago, I joined the paddle group and it was a stretch of river that I’d never been on because I didn’t want to get that rash again,” Hostler said. “And then being with the group, it settled with me that this was a triumph of a spirit coming back to the river, that we get to live with the river again after so many of us had to stay away from the river because of the contamination.” 

Seeing the young kayakers paddle the river, after experiencing decades of violence, protests and legal battles over fishing and water rights on the Klamath, brought him to tears. 

Clarence Hostler, of the Hoopa Valley, Yurok and Karuk tribes, waits on the shore at the mouth of the Klamath River to greet the young Indigenous paddlers as they reach the ocean. Having grown up on the river in the 1950s, Hostler witnessed decades of violence, protests and legal battles over fishing and water rights before the dams were removed last fall. (Eleanor Bennett / Aspen Journalism & Aspen Public Radio)

“A lot of the early warriors had to do the difficult work, and there are some of us, older ones, who carry the knowledge of old ways,” Hostler said. “But now, some real work starts with these young people who are activists on the water because there’s more contaminated water yet that needs to be worked on.”

As Carmen and her fellow kayakers reached the ocean and splashed in the waves, she felt the weight of that history. 

“We shouldn’t be having to do this — like, there shouldn’t have been dams in the first place — but we fought a lot for nearly a century, for decades and decades, and now dams are finally out,” Carmen said. 

Even with feelings of sadness and frustration over what her people endured, Carmen is proud of what she and her peers accomplished. 

“We’re making history,” she said. “This is something I never thought I’d ever do, but I’m doing it today.”

Now that the dams are out, Carmen and several of the other young kayakers who have already started their own kayak clubs, are looking forward to returning to their communities to help the next generation of young paddlers reclaim their rivers and their ancestry.  

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

As Gross Reservoir rises, Boulder County residents grapple with project’s legal turmoil

By
Cassie Sherwood, The Water Desk
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Cranes and construction equipment line the shore at Gross Reservoir on June 19, 2025 in Boulder County, Colorado. The construction is part of an expansion project that will supply water to Denver’s residents. (Cassie Sherwood/The Water Desk)

Pieter Strauss used to love hosting stargazing parties at his house in the Lakeshore Park neighborhood up Flagstaff Road southwest of Boulder. The hobbyist astronomer would fire up the barbecue and spend hours showing his neighbors the night sky through his observatory and telescopes. 

Strauss’s house sits looking directly over Gross Reservoir, which provides water to Denver residents.

But when a project to significantly raise the reservoir’s dam began construction in 2022, those moments of neighborhood tranquility were lost for some residents. For Strauss the biggest impact was the bright construction lights used to keep work moving overnight. 

“It became impossible to sit on the deck before sunrise and after sundown, astrophotography was impossible. They lit up the skies,” with powerful floodlights, Strauss said. 

For over 20 years, residents and various environmental groups have protested the project, which suffered a series of legal blows this year. Construction on the massive dam ground to a halt in April amidst the courtroom wrangling, and subsequent decisions have cast a new level of uncertainty over large-scale water projects that propose to draw on the beleaguered Colorado River.  

However, by the end of May, federal courts ruled that construction could continue due to concerns surrounding uncompleted construction and potential flooding possibilities, but that the reservoir could not be filled. 

Raising the dam 

Gross Reservoir’s dam is owned and operated by Denver Water. The utility built it in the 1950s, with two other building phases planned to accommodate future water needs. The current dam expansion will raise the height of the dam 131 feet, tripling the current capacity of the reservoir, and providing more water for Denver Water customers. 

The construction was spurred by “a combination of demands in our system, as well as concerns about climate and concerns about the needs for greater resilience in our system,” said Jessica Brody, general counsel for Denver Water. 

The need for the expansion is similar to a bank savings account, Brody said. Tripling the capacity of the reservoir is a savings account that can be drawn on in circumstances of an emergency.

“If we have an extreme drought event, we want to have more water banks that we can help smooth the impacts to our customers,” Brody said. 

When the utility initially announced plans to begin moving forward with a dam expansion, residents of the area were concerned. Environmental threats and the disruptions from the massive construction project topped the list of worries. They attended meetings at town halls with county commissioners. They organized with other residents in and around Coal Creek canyon.

While some residents fought the expansion, others anticipated it. When the dam was initially constructed, the utility planned to expand further down the line. 

Since construction began in 2022, residents have experienced noise and light pollution. Five neighbors have moved from the Lakeshore Park neighborhood. Pieter Strauss, at whose house they once held stargazing gatherings, was among them. 

Beverly Kurtz, member of TEG, on Pieter Strauss’s former porch overlooking Gross Reservoir on June 19, 2025. Once construction began, Strauss was no longer able to host neighborhood stargazing parties due to light pollution. (Cassie Sherwood/The Water Desk)

“The most valuable thing to all the people who have moved up here is that they had a quiet nature sanctuary. But then when you take that away, is it worth it?” said Anna McDermott, another resident of the area. 

“We sleep with our windows open. Not one house has air conditioning, so you sleep with your windows open in the summer months,” she said.  “You hear these giant backup beepers crashing, grinding all night long. Even with earplugs, I can’t sleep.” 

The Environmental Group (TEG) is an organization of residents in the Lakeshore Park neighborhood and surrounding residents, focused on engaging the community in action when environmental issues arise. Along with Save the Colorado, The Sierra Club, and other environmental organizations, TEG has fought the expansion. Beverly Kurtz, former president of TEG, has worked to hold Denver Water and the companies working on the dam, Kiewit Corp. and Barnard Construction Company Inc., accountable during construction. 

Heavy duty trucks are required to use a different road to access the dam rather than the paved road up Flagstaff Mountain due to fire concerns. Large semi-trucks have slid off the road due to the steep grade, which can cause traffic jams and road closures. 

“At one point they had one of the two roads down this mountain closed for five months,” Kurtz said. “It wasn’t until we called the sheriff out here and he realized the safety concern that they opened the road back up.”

Legal snares slow construction

In October 2024, two years after construction began, Save the Colorado, along with other environmental groups, won a lawsuit against Denver Water. U.S. District Court judge Christine Arguello found the utility’s dam construction permit violated the Clean Water Act and the National Environmental Policy Act. At the time, construction was able to continue and Arguello ordered the groups to work out an agreement regarding damages. 

In April 2025, the judge ordered a temporary halt on construction. The initial lawsuit argued that the U.S. Army Corps of Engineers, who provided the project permitting, did not fully consider climate change impacts when it approved the dam’s expansion. 

A month later, Arguello ruled that Denver Water could finish construction on raising the dam, but that the reservoir could not be filled until the Army Corps reissued the permits.

“If you stop the construction of a dam when it is partially built, the dam doesn’t function as it was ultimately designed to function,” said Denver Water’s Brody. “That was a big concern of ours and the Federal Energy Regulatory Commission.”

The utility has also been ordered to not remove any additional trees surrounding the dam until the proper permits are obtained. The project proposes the removal of over 200,000 trees. 

Arguello’s opinion also called into question the underlying water rights Denver Water would rely on to fill the newly enlarged reservoir when construction finished. Gross Reservoir is filled with water from the headwaters of the Colorado River, which has experienced steep declines in water supply amid a long-term warming and drying trend in the Rocky Mountains. 

“The Environmental Impact Statement didn’t even look at the fact that the flows of the Colorado River are in decline. Most of the science suggests they will continue to decline further,” said Doug Kenney, Western Water Policy Program director at the University of Colorado Boulder’s Natural Resources Law Center. Acquiring new permits will require Denver Water to redefine the project’s purpose and evaluate the environmental damage, he said.

The case is more than a local water project. Diverting more water across the western slope of Colorado has created concerns for ecosystems throughout the overappropriated watershed and for communities downstream in California, Nevada and Arizona. 

“It makes it more difficult to ensure that there’s sufficient flow downstream as a result,” Kenney said. “We have got to stop this practice of taking more and more water out of the upper reaches of the Colorado River because it just increases the stress on a river that is already under a tremendous amount of stress.”

By calling into question the project’s potential to have downstream impacts, the decision could add a new legal hurdle future water development infrastructure will have to clear. 

“Historically, agencies in recent decades have not done enough to consider climate change in decisions,” Kenney said. Cases like this one need to happen in natural resource law more generally, he said, as they help establish precedents for future projects that could potentially put the environment at risk. 

Denver Water is appealing the court decisions that bar the expansion. That could result in a reissue of the permits with a redefined purpose or a dismissal of the court rulings made earlier this year. 

“We think that the district court made some misjudgements or misinterpretations when it found the Army Corps committed these errors,” Brody said. 

Learning to live alongside it

Amid the stops and starts of Gross Reservoir construction, nearby residents are not ready to let go of what they used to have. 

Kurtz and McDermott recall their old activities along the reservoir’s north shore. A handful of neighbors would walk their dogs everyday along the hiking trail that connected the reservoir to their neighborhood. The trail has since been widened significantly, to allow for excavating equipment. They would host Memorial Day parties along the water’s edge. 

Beverly Kurtz and Anna McDermott, longtime residents of the Lakeshore Park neighborhood pose in front of Gross Reservoir on June 19, 2025. They are members of TEG, an environmental group involved in a lawsuit against Denver Water. (Cassie Sherwood/The Water Desk)

Now they minimize their excursions to the shore as much as they can. At this point they’re more than ready for construction to be completed, exhausted from the daily disruptions, explosions and drilling. 

“Now clearly, when the work is done, the things which negatively impacted my life would go away. But I couldn’t last them out,” Strauss said. He recently relocated to the Boulder area. “It was just my bad luck that my golden years coincided with the worst effects of the project.” 

Some residents found that the expansion project has renewed their sense of community in Lakeshore Park.

“In a weird way a lot of us have gotten even closer because we were in the battle together,” Kurtz said. “We feel like at this point we won the battle, but we’ve lost the war.”

“They will get the permits to eventually fill this reservoir following the expansion,” she said. 

However, federal courts requiring the proper permits to continue construction is a win in her and TEG’s book, as it sets a precedent for any large construction processes that occur in the future. It will ensure that the proper environmental permits are obtained before construction can begin on a project. 

“If nothing else, we hope that precedent still stands. Because it will help somebody else,” she said. 

This story was produced by The Water Desk, an independent journalism initiative at the University of Colorado Boulder’s Center for Environmental Journalism. 

Wyoming’s crowded Lonesome Lake tops EPA’s national survey for fecal contamination

By
Mike Koshmrl, WyoFile
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Dogs are permitted and regularly accompany human hikers into places like the Cirque of the Towers, but the domestic animals leave behind waste that may be contributing to water quality issues. (Mike Koshmrl/WyoFile)

LONESOME LAKE, WYOMING—Whit Coleman belly flopped with style into some of Wyoming’s most famous alpine waters on a summer day.

Out on a father-son backpacking trip with friends, the Salt Lake City man took the plunge with an incredible backdrop: the Wind River Range’s Cirque of the Towers, a semi-circle of big-walled granite peaks that all top 12,000 feet. The dip was pleasant, he recalled later in the day. 

“It’s probably better that we didn’t know,” Coleman said. “We enjoyed ourselves. I’m not too worried about getting sick.” 

Coleman learned of a potential health concern after the fact while hiking out from Lonesome Lake, which sits at the bottom of the cirque and forms the headwaters of the North Popo Agie River. 

Lonesome Lake has long been reputed to be unfit for drinking and even swimming. That’s due to contamination presumed to be from the hordes of humans who poop while traveling through the popular backcountry basin. Now there’s a datapoint to back it up. 

On Aug. 9, 2022, during the height of the recreation season, environmental regulators gathered a water sample from a foot below the surface near the outlet of Lonesome Lake.

The concentration of Enterococci — bacteria indicative of fecal matter — jumped off the page. 

The U.S. Environmental Protection Agency didn’t make the results public for two years. When they were published, heads turned. 

Lonesome Lake’s sample contained 490,895 calibrator cell equivalents of Enterococci for every 100 milliliters. The EPA’s safety threshold for swimming is 1,280 CCE/100 mL. 

The concentration of fecal bacteria, in other words, was 384 times greater than the EPA’s criteria. Not only that, but the fecal bacteria were more concentrated in Lonesome Lake than in any of the other 981 lakes that were surveyed around the country for the federal agency’s National Lakes Assessment, which gathers data for randomly selected ponds, lakes and reservoirs every five years.

A group of backpackers from the Salt Lake City area cross the outlet of Lonesome Lake on July 9, 2025.  (Mike Koshmrl/WyoFile)

Arguably, Lonesome Lake was the most spectacular, remote waterbody in the broad study examining lake health all around the United States. Its snowmelt-fed 35 acres of crystal clear water, located within the Popo Agie Wilderness, are just a half mile off the Continental Divide along the spine of a mountain range that hosts more than two dozen glaciers and the highest peak in Wyoming. 

And yet the data also suggested that Lonesome Lake’s water was the most polluted by poop. That’s especially remarkable given that the assessment also looked at lakes and ponds in urban areas and agricultural regions more typically associated with feces-related pollution. 

Early in the process

The sky-high Enterococci concentration found during the EPA’s 2022 survey — sampling conducted by the Wyoming Department of Environmental Quality — set off a chain of events.

Because of its location in a designated wilderness area, Lonesome Lake is classified by Wyoming as a “Class 1” water. That’s a designation that protects uses like “primary contact recreation,” and demands that “nonpoint sources of pollution” be controlled through “best management practices.” 

The DEQ and the Shoshone National Forest decided they needed more data to understand the scope of what’s going on. 

“A single datapoint doesn’t necessarily tell us much of anything,” said Ron Steg, DEQ’s Lander Office Manager. “We need to get some real data to understand if there is a problem. If there is, we’ll react to the results of the data.”

Jackass Pass sits along the Continental Divide, and also marks the dividing line between wilderness areas in the Bridger-Teton and Shoshone national forests. The pass descends east into the Cirque of the Towers, which surrounds Lonesome Lake. (Mike Koshmrl/WyoFile)

In October 2022, weeks after the EPA results came out, staffers with the federal and state agencies trekked into the cirque to conduct follow-up testing. Gathering water samples outside of the busy backpacking and climbing season — trail-counter data shows that use virtually shuts off entirely come mid-September — they weren’t able to detect any levels of another fecal indicator bacteria, Escherichia coli (E. coli).

That sample was collected “well past peak recreation season, from a source standpoint,” said Jeremy ZumBerge, who supervises DEQ’s Surface Water Monitoring Program. “You’re also past peak exposure time — when people are most likely to be exposed.” 

Water near popular recreation areas in Lonesome and Big Sandy lakes is being sampled five times during the busy summer backpacking season in 2025. The Wyoming Department of Environmental Quality probe could precede an impairment designation in one or both lakes, if regulators detect dangerous levels of E. coli bacteria. (Wyoming Department of Environmental Quality.)

This summer, a much more extensive effort is underway to suss out what exactly is going on in Lonesome Lake. Between July 14 and Sept. 11, DEQ and U.S. Forest Service officials will take five samples near the south and west shore, where trails come down off of Jackass Pass and the North Fork and concentrate use. While they’re at it, the team of hydrologists and watershed protection specialists will also take water samples from Big Sandy Lake, located on the Bridger-Teton National Forest.

“That was of interest to the Forest Service, knowing that Big Sandy is also a very popular destination — and it is very convenient, as it’s off the main trail used to access Lonesome Lake,” ZumBerge said. 

The specifics of the joint state-federal investigation are laid out in a “sampling and analysis plan” for Lonesome and Big Sandy lakes that Wyoming DEQ published in March. The results will be published in a subsequent DEQ assessment report.

The scientific inquiry has the potential to elucidate an environmental hazard that frequent Wind River Range travelers have long been aware of. It’s no secret: Lonesome Lake’s diminutive watershed — just 2 square miles — is thought to be overrun with poop that makes its water unsafe. The guidance is all over the place online, and is also frequently passed along word of mouth. 

The south and west reaches of Lonesome Lake are visibly shallow in this July 2025 photo taken while descending from Jackass Pass. Long reputed to have quality issues related to human waste, the Shoshone National Forest lake is being examined for an E. coli impairment after regulators initially detected fecal bacteria levels several hundred times more than is believed to be safe. (Mike Koshmrl/WyoFile)

Poop lake

“I tell people definitely do not swim in there, I tell people definitely do not drink the water,” said Brian Cromack, an employee of Pinedale’s Great Outdoor Shop who often advises Wind River Range travelers. “It’s been heavily contaminated for a long time, just via the negligence of outdoor recreation enthusiasts over the years.” 

Fecal bacteria readings 384 times the safety threshold “sounds about right,” Cromack said. 

“Hopefully, people are more mindful,” Cromack said. “I think the big problem why Lonesome Lake is so bad is because of the serious climbing prevalence there. Generally, backpackers are a little bit more conscientious about how to dispose of their waste. Not to rag on any one group — I love to climb.” 

The Shoshone National Forest has imposed special regulations to protect the water and resources near Lonesome Lake, one of the most-visited interior destinations in the Wind River Range. The restrictions may not be enough to protect the lake from contamination from human feces. (Mike Koshmrl/WyoFile)

Regardless of who’s doing the pooping, there’s a lot of it and it’s easy to find. 

WyoFile visited Lonesome Lake in July and within minutes found seven makeshift latrines in likely areas — in the trees, not far off the trail. Most were loosely buried to varying degrees. In other places, toilet paper and excrement had become exposed. 

And it’s not yet peak busy season. Early July, according to the trail-counter data, attracts 100 people or fewer to Lonesome Lake weekly. By early August, the weekly counts crest 250 wilderness travelers, and by the middle of August, a whopping 400 people are trekking into the Cirque of the Towers every seven days. 

The Shoshone National Forest has imposed special regulations to protect the water and resources near Lonesome Lake, one of the most-visited interior destinations in the Wind River Range. The restrictions may not be enough to protect the lake from contamination from human feces. (Mike Koshmrl/WyoFile)

Collectively, it’s a lot of biomass. A decent chunk of it gets left behind. Back-of-the-napkin poop math suggests that, at roughly a quarter pound per stool, perhaps 100 pounds of human feces are getting squished under rocks or buried in the shallow soil that rings Lonesome Lake on a weekly basis during the height of summer. 

“I don’t know specifically how that [fecal bacteria] transport to the lake could occur,” said ZumBerge, the Surface Water Monitoring Program supervisor. “I imagine there’s a few different ways that transport can make it to the lake — if it’s happening.” 

At between 10,000 feet and nearly 13,000 feet in elevation, the Cirque of the Towers and the basin it surrounds are buried by feet of snow each winter. It melts off in the spring and summer, bound for the low point of Lonesome Lake.  

Possible fixes?

Hiking along Lonesome Lake’s southern shoreline on a July afternoon, Glenwood Springs, Colorado, resident Carl Meinecke, an arborist, wasn’t so shocked by the fecal phenomenon.

“It’s not completely surprising,” Meinecke said. “Things aren’t like they used to be. We’re getting such high use in some of these areas, it becomes tricky.” 

Carl Meinecke, a Roaring Fork Valley, Colorado arborist, reflects on human use-related water quality issues suspected to be plaguing Lonesome Lake, in the background. (Mike Koshmrl/WyoFile)

The regulations on many western rivers, he pointed out, require that campers carry out their waste in specialized containers known as wag bags or a groover. 

“That would be pretty tough here, carrying it out,” Meinecke said.

It wouldn’t be unheard of. 

As nearby as Grand Teton National Park, poop-removal regulations are in place. Portable toilet systems are required for backcountry camping on Jackson Lake and all overnight users of Garnet Canyon must pack out their human waste in EPA-approved containers, according to the park regulations. 

Steg, at the DEQ, emphasized that it’s tough to know what the future holds. But if the data bears out, he said, the fecal bacteria concentrations will “certainly need to be addressed.”

“It’s a very unique situation to have a water quality issue this many miles into a wilderness area,” Steg said. “It’s not something that any of us have regularly dealt with. We’ll see where the data points us.” 

ZumBerge, his DEQ colleague, was unaware of any other Wyoming waters where human use has been implicated in a fecal bacteria problem. During the 2022 EPA assessment, there were 27 total lakes randomly sampled in the state, including six in the Wind River Range. 

“Lonesome was the only one that rose to our attention as being potentially elevated,” ZumBerge said. 

Environmental regulators do have tools at their disposal designed to address water quality problems. “Total maximum daily load” [TMDL] plans, for example, are years-long strategies commonly used to bring waterways into compliance with the Clean Water Act. In Wyoming, they’ve been used to attempt to address livestock feces-related E. coli bacteria pollution in places like Star Valley’s Salt River. 

Steg, who supervises that program, said it’s way too early to say if a TMDL will be necessary for Lonesome Lake. 

“That’s a pretty big tool for a pretty simple problem — if, in fact, there is a problem,” he said. 

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

Once a showcase of American optimism and engineering, Hoover Dam faces new power generation declines

By
Brett Walton, Circle of Blue
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Hoover Dam holds back the waters of the Colorado River at the Arizona-Nevada state line. (J. Carl Ganter/Circle of Blue)

The long-term drying of the American Southwest poses a gathering and measurable threat to hydropower generation in the Colorado River basin.

Should Lake Mead, the reservoir formed by Hoover Dam, continue to shrink, a substantial drop in the dam’s hydropower output is on the horizon. 

The diminished state of the lake and the potential severe drop in electricity supply illustrate the consequences of a warming climate for the region. Built in the throes of the Great Depression, Hoover was the signature project of a country displaying its grit and engineering prowess to tame the West’s mightiest rivers to irrigate farmland and build cities. Today the dam is an aging asset buffeted by hydrological change and generating half the power that it did just a generation ago. 

According to the Bureau of Reclamation, the federal agency that manages the basin’s large dams, if Lake Mead falls another 20 feet, Hoover Dam’s capacity to generate electricity would be slashed by 70 percent from its current level. 

If there is a reason not to be especially alarmed it’s this: Hoover is just a small piece of the region’s electric power infrastructure. Federal dams along the Colorado River account for just over 4 percent of Arizona’s generating capacity, for instance. 

Still, the cheap electricity is a lifeline for tribes and small rural electric providers. And the dam’s ability to be quickly turned on and off helps regulate the peaks and troughs of electricity demand. Curtailing this source of inexpensive electricity would raise the cost of power in the region while also challenging the integration of renewable energy into the electric grid.

A hydropower shortfall will be “bad news for us,” said 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.

Lake Mead now sits at an elevation of 1,055 feet. The break point for hydropower is 1,035 feet. At that level, 12 older turbines at Hoover that are not designed for low reservoir levels would be shut down, Reclamation said. Five newer turbines installed a decade ago would continue to generate power.

Hoover Dam, at the center of the photo, forms Lake Mead, which is currently just 31 percent full. (J. Carl Ganter/Circle of Blue)

The threat is real, especially as this year’s runoff forecast for the basin continues to worsen. Every month, Reclamation updates its projection of reservoir levels over the next two years. The June update shows a 10 percent chance that Lake Mead breaches 1,035 feet in spring 2027. 

In a worst-case scenario, the breach would happen at the end of 2026, just when current operating rules for Lake Mead and Lake Powell expire. The modeling indicates a similar chance that Lake Powell drops low enough in 2027 that Glen Canyon Dam, another key hydropower asset in the basin, stops producing electricity.

The probability that Lake Mead drops that far is small and laden with uncertainties about weather and water use. But it is large enough that Hoover’s power customers are signaling their concern.

Reclamation, for its part, acknowledges the problem at Hoover and is evaluating its options. The agency estimates that replacing the 12 turbines would cost $156 million.

“Reclamation is assessing the cost-benefit analysis of replacing some of the older style turbines and the timeline for installation,” the agency wrote in a statement to Circle of Blue. “Ordering new turbines is a lengthy process as they have to be designed, model tested, built and ultimately installed.”

The dozen older turbines are not designed to operate at low reservoir levels. Dams like Hoover, which was completed in 1936, function based on the principle of hydraulic head, which is the difference in elevation between the top of the reservoir and the intake pipes for the dam’s powerhouse. When the hydraulic head drops, so does the water pressure. That can trigger the formation of air bubbles in the water, which can gouge and damage the turbines in a process called cavitation.

The five turbines that would not be shut down are low-head units that can accommodate lower reservoir levels. Installed a decade ago at a cost of $42 million in response to a previous rapid decline in Lake Mead, they can operate down to 950 feet. (One of those five turbines is currently offline, and Reclamation does not have an estimate for when it will resume operating.)

Hoover is already hobbled by low water. Power generation in 2023 was roughly half the output of 2000, the last year that Lake Mead was effectively full.

When Lake Mead is full, Hoover has a generating capacity of 2,080 megawatts, equivalent to a large coal-fired or nuclear power plant. Today its capacity is 1,304 MW. If the dozen older turbines go offline, it will drop again, to 382 MW.

These declines in hydropower generation have been felt by the customers who buy Hoover Dam’s electricity, Gerak said. In a shortfall, they have to buy market-rate electricity. Depending on the season and power demand, market rates can be considerably more expensive.

Eric Witkoski is the executive director of the Colorado River Commission of Nevada, which manages the state’s allocation of Hoover’s power. Witkoski said that rural electric companies in his state have a higher share of their electricity coming from the dams and would be most affected by a shortfall.

The value of Hoover’s electricity is measured not just in raw megawatts and dollars. It is a flexible power source that can be ramped up and down to match the region’s daily and seasonal rhythms. Energy use rises in summer afternoons when air conditioning units are blasting and electricity-consuming household chores are at hand. It falls at night when cooler air prevails and washing machines are silent.

“The beauty of hydropower is that it’s great for helping to stabilize and regulate the grid,” Gerak said.

IEDA and other interest groups are pursuing a number of fixes. They are encouraging Reclamation and its parent agency the Interior Department to use federal infrastructure funds to install new low-head turbines or to request appropriations from Congress.

They are writing their congressional representatives in support of the Help Hoover Dam Act, a bill that would unlock some $50 million in ratepayer funds that had been set aside for pension benefits for federal employees. The trade groups claim that Congress funds the pension benefits through other means and that the funds could be spent on dam upgrades if Reclamation was given the authority to do so.

They also want to set up an organization modeled after the National Parks Foundation that can accept donations for dam operations and maintenance, including the visitor center, which is supported by power sales.

These fixes will take time. But as Lake Mead declines, the urgency to achieve them will intensify.

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

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

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

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

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

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

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

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

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

What is a snow drought? How is it defined?

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

What is the connection between snow droughts and climate change? 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Meeting multiple needs at once

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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