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Aspen Journalism: U.S. Forest Service presents results of beaver inventory

Heather Sackett
Aspen Journalism
Beavers have constructed a network of dams and lodges on this Woody Creek property. Pitkin County funded a two-year beaver inventory in the headwaters of the Roaring Fork and its tributaries.
Heather Sackett/Aspen Journalism

Thanks to Pitkin County, local land managers now have more information about beavers and their habitat, which could eventually lead to projects aimed at improving stream conditions.

Over the summers of 2023 and 2024, technicians with the U.S. Forest Service covered roughly 353,000 acres of land throughout the headwaters of the Roaring Fork River and its tributaries, surveying 296 randomly chosen sites on 66 streams for beavers, their dams and lodges, or other signs they had once been there, like chewed sticks. The surveys, which were funded with $100,000 from Pitkin County Healthy Rivers, found that 17% of the sites were currently occupied by beaver, 34% of the sites had some signs of beaver, and 37% of sites had evidence of past beaver occupation. 

Clay Ramey, a fisheries biologist with the White River National Forest, presented the findings of the two-year inventory to the Healthy Rivers board at its regular meeting on Thursday evening. 



“At almost one out of five sites, there were beavers actually living there,” Ramey said in an interview with Aspen Journalism. “We have beavers on the forest, and they are spread out all over the place. I thought that was good news, that we’re not starting from some place of zero beavers.”

Still, the inventory confirmed that there are not as many beavers as there used to be, and that they prefer certain areas over others: streams that are not too steep, with lots of willow, aspen, alder, and other riparian vegetation they can use for food and to build dams and homes. Steep streams or areas with lots of conifer trees did not seem to support beaver populations. 




“We found there were clear patterns with these beaver,” Ramey said. “We find them in very specific places. They are not just willy-nilly spread out across the landscape.”

The stream with the highest percentage of sites currently occupied by beavers, at 58%, was Mill Creek/Cattle Creek on the northern flanks of Basalt Mountain. The next-most beaver-rich streams were Hunter Creek, Deeds Creek (a tributary of the Fryingpan River), Thompson Creek and Maroon Creek, where 20-23% of the sites surveyed currently support beavers.

The headwaters of the North Fork of the Fryingpan River and Lime Creek did not have any sites currently occupied by beaver, and only 4% of sites on the headwaters of the Fryingpan River were home to beaver. 

“It would seem that while beaver were once common there, the vegetation has shifted from aspen to conifer, and therefore that area doesn’t appear to have a lot of potential for beaver in its current state,” the inventory report reads.

Another interesting finding from the inventory is that there is less willow found in areas where cattle graze. But what that means for beavers is unclear. 

“The beavers are occupying grazed areas and ungrazed areas basically to the same extent,” Ramey said. “So there was nothing to suggest that beavers are avoiding or being excluded from grazed areas.”

Samantha Alford, right, and Stephanie Lewis, technicians with the U.S. Forest Service, measure the slope and width of Conundrum Creek in summer 2023. A two-year inventory of beavers in the headwaters of the Roaring Fork watershed recorded where beavers currently live and where they lived in the past.
Heather Sackett/Aspen Journalism

The information gleaned from the inventory will now help the Forest Service decide where to do prescribed burns and stream restoration projects in an effort to create more and better beaver habitat. Ramey said the Forest Service is undergoing a National Environmental Protection Act process for projects on Fourmile Creek and Middle Thompson Creek. Both creeks had evidence of extensive use by beavers in the past, but Fourmile in particular is currently under-utilized by the animals, with only 3% of sites currently occupied by beavers. Growing more willows may entice beavers back.

Pitkin County Healthy Rivers, whose mission includes improving water quality and quantity, has been working over the past few years to educate the public about the benefits to the ecosystem of having North America’s largest rodent on the landscape. Funding the Forest Service beaver inventory is part of the organization’s “Bring Back Beavers” campaign. 

Prized for their pelts by early trappers and later seen as a nuisance to farmers and ranchers, beavers were killed in large numbers, and their populations have still not fully recovered. But there has been a growing recognition in recent years that beavers play a crucial role in the health of ecosystems. By building dams that pool water, the engineers of the forest can transform channelized streams into sprawling, soggy floodplains that recharge groundwater, create habitat for other species, improve water quality, and create areas resistant to wildfires and climate change. 

Healthy Rivers Board Chair Kirstin Neff said the ultimate driver of the organization’s commitment to bringing back beavers is an interest in the health of the Roaring Fork watershed. 

“Our goal is to get good habitat work done on the ground,” Neff said. “The things we’re concerned about are water availability for wildlife and downstream users and things like wildfire risk.” 

Aspen Journalism, which is solely responsible for its editorial content, is supported by a grant from the Pitkin County Healthy Community Fund.

Aspen Journalism
Aspen Journalism

This story is provided by Aspen Journalism, a nonprofit, investigative news organization covering water, environment, social justice and more. Visit aspenjournalism.org.

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