CEDAR CITY — Nature’s engineers — beavers — have an incredible impact on the environments they inhabit. The semiaquatic rodents’ influence doesn’t disappear from the landscape when they do and ecosystems can undergo major changes in their absence.
For this reason, multiple artificial beaver dams were built in Southern Utah this summer; but what are there potential benefits for local ecosystems?
While the North American beaver (Castor canadensis) was once common throughout the U.S., fur trapping “decimated” their population, making the rodents and their dams a rare sight, according to this Wild Aware Utah publication. In 1899, Utah closed its beaver harvest.
The keystone species supports various other plants and animals “through their dam building and hydrological engineering” and benefits humans by enhancing fisheries, steadying water flow, aiding flood control, and storing water and sediment, among their other impacts.
“Beaver have since recolonized a large portion of their former range, however, loss of habitat due largely to competing land uses, has severely limited populations in many areas throughout Utah,” the document reads.
“Beaver populations never fully recovered from the losses they incurred with widespread trapping in the 1800s,” Wild Aware Utah writes. “In their absence, much of their historic streamside habitat abundant with cottonwood, aspen, or willow has been repurposed or degraded by other land uses, such as water development and livestock grazing.”
To restore historic meadows and wetlands near Parogonah, the Utah Division of Wildlife Resources teamed up with the U.S. Fish and Wildlife Service and other public and private entities to build beaver dam analogs in Little Creek. Beaver dam analogs are artificial dams built by humans to mimic beavers’ impact on the landscape.
The work is part of the Partners for Fish and Wildlife Program, which provides free technical and financial assistance to partners to improve wildlife habitat, Fish and Wildlife Biologist Clint Wirick told St. George News.
The division and the Natural Resource Conservation Service funded the project, said Stan Gurley, a farm bill wildlife biologist with the Utah DWR.
Why build artificial beaver dams?
“We’ve got an erosion problem for a lot of reasons … but a lot of times, our water is just shooting down the mountain — not staying up there — and it’s gone,” Wirick said. “And our flood plains are disconnected from the stream, what soils used to hold water in them no longer do and are dry, and you’re seeing them converted to shrub lands.”
Beaver dams can cause sediment to build up where the stream previously downcut the earth, reconnecting the flood plain. This will allow water to percolate through the soil, recharging nearby springs, Gurley said.
Because the dams hold more moisture in the soil, they can prevent erosion and allow grass to grow. They cause pond formation, expanding wetland and meadow habitat. This increases access to food sources like grasses, insects and forbs, a type of flowering plant. Wild Aware Utah writes that dams increase stream complexity, creating better habitats for aquatic species.
As the landscape changes, Wirick said multiple species, such as pollinators and sagebrush songbirds, like greater sage grouse, sage sparrows or sage thrashers, which have been “declining pretty heavily,” stand to benefit, Wirick said.
“With wildlife, we call them (green areas) the ‘green groceries,'” Gurley said. “The longer you have greener vegetation, that vegetation is more beneficial to wildlife in this summertime period, where they’re trying to build fat reserves to get them through the winter.”
Insects are a “crucial part of the protein that (sage grouse) need to grow” and are naturally drawn to green areas, Gurley said. Additionally, the landowner’s livestock will benefit from additional forage.
By slowing water flow, more water moves downstream when it’s hot, Wirick said. The area acts as a sponge, holding water; when temperatures rise, the pressure causes it to leak back out.
“We’re not impounding water or holding water for wildlife or trying to take water away from ranchers or communities,” Gurley said. “But water is there to benefit the whole entire watershed, which in turn should benefit the downstream user.”
How to build the dam
The process is simple.
Workers pounded fence posts into the ground, starting at the bank. One woman used a chain saw to remove branches from a nearby juniper tree. The branches were then woven through the posts with the help of two others.
Then, they took sod from around the stream and packed it at the base of the dam to allow water to flow through, Gurley said.
“We’re not trying to create this perfect dam where it flows over one spot,” he explained. “We want it to leak a little bit. We want it to be like a natural dam would be.”
Each dam typically takes between one to six hours to build, depending on the size and availability of materials and workers, Gurley said. Then, a fence is built around the area to protect the dams from grazing cattle and other threats.
“It’s one of those techniques that have become really popular just because anybody can do it,” Wirick said. “And you get results pretty quick. Do I think we need to be doing them everywhere in every stream? No. I think that can be done in the right place at the right time.”
The agencies speak with nearby homeowners, irrigation companies and others to ensure that the dams won’t create issues. Wirick said the closer the stream is to civilization, the more complicated the work becomes.
“They aren’t a fit everywhere,” he said.
Land stewards try to visit the dams at least once a year, Wirick said, adding that they often do so several times annually for the first few years to ensure they’re intact and working as intended. The structures aren’t meant to be permanent and can disappear under sediment, begin allowing more water through one side, or otherwise cease functioning.
Still, Wirick said they can benefit the ecosystem far longer than they remain intact.
While not the case in Little Creek, sometimes beavers are released on-site. Or, the mammals travel down the mountain or downstream and build onto the artificial dams, Wirick said.
Project sites are often chosen in areas where beavers are located, Gurley said. They plant willows and other riparian vegetation, allowing the rodents to take over and begin maintaining the artificial dams themselves.
“That’s one thing we have found through using BDAs (beaver dam analogs) is we’re really good at putting them in, but maintaining them is a whole different story,” he said. “It takes a lot of labor to maintain them, but if you can get a beaver to do it — they are attracted. Beavers seek out the sound of flowing water, so we’ve seen them come in and essentially adopt, or annex, if you will, these BDAs and begin using them. … We want Mother Nature to take over.”
Photo Gallery
A beaver dam analog stands in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Little Creek flows into an artificial beaver dam, near Paragonah, Utah, Aug. 14, 2023 | Photo by Alysha Lundgren, Cedar City News A fence protects beaver dam analogs in Little Creek, near Paragonah, Utah, Aug. 14, 2023 | Photo by Alysha Lundgren, Cedar City News Wildlife biologist Stan Gurley explains how to make a beaver dam analog near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Grass grows by Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Little Creek flows freely, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Two women place fence posts to build an artificial beaver dam in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Two women place fence posts to build an artificial beaver dam in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News workers build an artificial beaver dam in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Fence posts stick out of the soggy ground by Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News A woman gathers juniper branches to build an artificial beaver dam in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Natural debris block water in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News Sage brush grows near Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News A beaver dam analog stands in Little Creek, near Paragonah, Utah, Aug. 2, 2023 | Photo by Alysha Lundgren, Cedar City News A North American beaver is gnawing on wood in this stock image | Photo by mitumal/iStock/Getty Images Plus, St. George News A North American beaver enjoying a meal in this stock image | Photo by exs/iStock/Getty Images Plus, St. George News
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