Western Dry Forests and Fires Stories
Measures of Snow
How Research is Connecting Forest Restoration to Western Water Supply
By Kate O’Neill, Writer/Editor for The Nature Conservancy
One crisp winter day on a forested hillside in south-central Wyoming, a camera strapped to a tree clicks, capturing an image of a snow-covered measuring stick. A simple set-up that is easy to miss, this technology is starting to appear in dry forest ecosystems across the West. It’s part of a growing network seeking to answer a common question: how do forest thinning and prescribed burning affect western snowpack, water supply and forest resilience?
Much of our water begins its journey in the forest, where snow accumulates, melts and soaks into the forest floor, then flows downstream, sustaining rivers, wildlife and communities along the way.
“Our forests in the western United States are natural water towers,” says Carli Kierstead, forest program director for The Nature Conservancy in Wyoming. “They play a key role in capturing and holding snow, then releasing it as snowmelt well into the summer as the water we use in our homes and that farmers use to grow our food.”
But forests in the West are changing. A century of fire suppression, paired with a shifting climate, has left them overgrown and vulnerable to increasingly severe wildfires, as well as drought. Severe wildfire can devastate water supplies, changing forest soils so they repel, rather than absorb, water and causing flooding and erosion that contaminates watersheds and reservoirs that store water for downstream communities.
To mitigate these risks, we need to increase the pace and scale of forest restoration treatments, activities like ecological thinning and prescribed burning that are designed to reduce overgrowth and increase forest resilience.
Enter snowtography—a method that uses cameras, measuring stakes and sensors to track snow depth over time. These images reveal how snow accumulates and melts under different forest conditions, from dense stands to areas that have been treated to reduce overgrowth. It’s inexpensive, replicable and surprisingly effective.
As researchers deploy snowtography across the western U.S., they’re uncovering new potential in time-tested forest restoration techniques. Thinning, the practice of removing small, overcrowded trees to support healthy forests, and prescribed fire don’t just reduce wildfire risk—they can also help forests hold more snow and release it slowly, keeping water on the landscape longer and helping trees stay healthy during dry months.
Building a Network for Answers
People have been using photography to track snow levels for decades in one form or another. But the question of how forest management techniques affect snow is a new one.
Snowtography can help tell us how to make necessary restoration activities, like thinning and prescribed fire, even more effective at helping forests hold onto more water.
Every forest has a different relationship with snow. Elevation, tree species, canopy density and slope orientation can change how snow falls, accumulates and melts. In Arizona’s dry forests, which are dominated primarily by ponderosa pine, snow might linger for just 60 days, while among Wyoming’s lodgepole pines it can stay for nearly five months. And snow depth doesn’t tell the whole story: density, or how much water the snow holds, matters too.
To account for these differences, a network of snowtography sites has grown across the West. TNC, the U.S. Department of Agriculture’s Agricultural Research Service and a wide variety of academic and local partners are pooling funding and expertise to gather rich data at these sites.
In Wyoming, Kierstead’s team leads snowtography monitoring in collaboration with the University of Wyoming. For the past two winters, the pursuit of data has sent researchers to two remote sites in the Sierra Madre mountains, traveling by car, then snowmobile and finally cross-country skis to access cameras and equipment.
Their snowtography sites are just two of many areas focused on the relationship between forest restoration and the water that feeds the Colorado River Basin and supports 40 million people.
“We’ve put out over a thousand snowtography measurement points across the Colorado River Basin,” says Joel Biederman, a research hydrologist with the Agricultural Research Service. “And every place we study is different, with different fire seasons and different water needs.”
The Agricultural Research Service collaborates with Wyoming and other state programs, playing a coordinating role in this effort due to the agency’s focus on scientific research and the important role of national forests in our water supply and agricultural production.
“Forested lands produce a major fraction of the fresh water that's available for farms, ranches, homes and businesses nationwide,” says Biederman. “Especially in the West, the biggest source of water for agriculture, for rural communities and even for urban communities is snowmelt from forested lands, and in many cases, it's from USDA National Forests.”
Quote: Joel Biederman
Forested lands produce a major fraction of the fresh water that's available for farms, ranches, homes and businesses nationwide.
Designing Forest Restoration Treatments From Snow Data
To turn the insights gleaned from each snowtography site into action, researchers are pairing snowtography with advanced modeling and machine learning to predict snow retention under different restoration scenarios across an entire forest. The effort also factors in topography and sun exposure to account for snow lost to evaporation or sublimation, the process where snow turns directly into water vapor without melting first.
Marcos Robles, TNC’s lead scientist in Arizona, is heading a study that’s applying the data to inform and scale forest management.
Preliminary analyses show that forest treatments could increase snow retention by 10 to 40 percent depending on forest type and how much snow falls in that year.
“The goal is that the data could be translated in a way that can help forest managers optimize how they do their treatments for water benefits,” says Robles. “Ultimately, we want to bend the curve so that forests and watersheds are more resilient under climate change.”
Biederman and local partners are testing this approach in Colorado’s Dolores River watershed, where snowtography sites have been collecting data for years.
“We’re at a transition point,” he says. “For the first time, we’re using snowtography data to help design forest management prescriptions at scales that matter for fire resilience and water supply.”
The project, supported by the Colorado Water Conservation Board and Colorado Strategic Wildfire Action Program, will use snow modeling to simulate how different thinning strategies affect snow retention and melt timing. The data will be used to plan restoration efforts, weighing water outcomes alongside wildfire risk reduction, wildlife habitat and scenic values.
The team will restore 40 acres of ponderosa forest adjacent to existing snowtography sites and monitor the results. Researchers are weighing questions like whether to accelerate snowmelt to reduce sublimation losses or prolong it to keep soil moist longer into fire season.
“If we can shorten summer for the trees, they may have more water when fire comes, helping fires burn less severely and boosting forest resilience to drought,” Biederman explains.
This pilot project lies in a critical region to address water scarcity. The Dolores River watershed is part of the Colorado River Basin; what happens in these forests ripples downstream, affecting reservoirs, hydropower and millions of people across the Southwest.
Successfully applying lessons learned here could help guide treatments on thousands of acres—helping managers design forests that hold more water, withstand fire and adapt to a changing climate.
From Treetops to Tide Flats
In Washington state, snowtography takes a new shape as it bridges the difference between the warmer maritime climate of the West Cascades and the drier region to the East. Emily Howe, a senior aquatic ecologist with TNC, has led studies here in collaboration with the University of Washington to examine snow retention and forest density.
Data from the team’s recent research has revealed that (similar to the temperate rainforests in the western Cascades) in the dry forests of the eastern Cascades, small gaps created in the forest canopy store nearly twice as much snow, compared to dense tree stands nearby. For the most part, the snow in these gaps melts within the same time frame as snow in denser parts of the forest. However, north-facing slopes are the exception. Here, snowpack can persist for up to 30 days longer in small forest gaps—a huge boost for spring flows.
The study was a rigorous effort, with the team climbing trees to strap cameras 15 feet off the ground, skiing into remote sites and scrambling over downed logs.
In recent years, this snowtography team has turned their attention to Cle Elum Ridge, where TNC is working with partners and the surrounding community to restore and steward nearly 10,000 acres of forest at the headwaters of the Yakima River basin. TNC staff worked with local foresters, together using ecological thinning to create a range of forest densities to test how critical restoration work could also help with water retention.
Overall, TNC’s forest treatments on Cle Elum Ridge increased snow storage by 12.3 acre feet of water for every 100 acres treated. The results could be pivotal for this fire-prone landscape, where the surrounding community is deeply invested in proactive restoration to avoid catastrophic wildfires, hold on to water resources, support the local recreation and large agricultural economy and protect threatened and endangered salmon.
As an ecologist who often works in coastal estuaries, Howe has seen the effects snowpack can have downstream firsthand.
“On bad snow years in the Cascades, our snow-fed rivers really struggle, too,” she says. “With less cold, fresh water pulsing into the river deltas in the late spring and early summer, the marsh plants and juvenile salmon start to fail as well. It’s all connected, from snow caps to white caps.”
Looking Ahead
The next decade will test the West’s ability to adapt to shrinking snowpacks, rising wildfire risk and water insecurity. Snowtography offers a scalable, data-driven approach: simple measurements combined with advanced modeling to guide forest restoration.
“We know active forest management will continue to be needed, whether it’s for wildfire risk reduction, timber stand improvement or wildlife habitat improvement” says Kierstead. “If we can provide some really robust science on how to do that in the best way possible for our water supplies, for our forests and for our communities, we want to do that.”
TNC’s Western Dry Forests Program is working closely with state programs throughout the West to advance and implement science-informed restoration, with the goal of improving dry forest health and resilience to threats like severe wildfires. Learn more.
We depend on forests. They depend on us.
Continue learning about The Nature Conservancy's Western Dry Forests program.
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