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Enjoy Magazine

Scott River Watershed Council's Beaver Dam Analogs

08/21/2019 11:00AM ● By Enjoy Magazine

Leave it to Beaver

September 2019
Story by Megan Peterson



IN 1836, fur trapper Stephen Meek explored a swampy basin 50 miles northwest of Mount Shasta. It would come to be known as Scott Valley, but to Meek, it was Beaver Valley, named after the plentiful semi-aquatic, industrious rodents that populated it. Back then, up to 1,800 beavers were trapped each year to supply the avaricious fur trade, and by 1929, the last of Scott Valley’s beavers had been skinned and sold. Fast-forward to 2019, when a group of volunteer activists and ranchers, led by the local non-profit Scott River Watershed Council, are encouraging beavers – and their ecological benefits – to return to Scott Valley. “When you talk about beavers, people usually have a strong opinion one way or the other,” quips the council’s executive director, Charnna Gilmore.  

Beavers, or Castor canadensis, are the largest rodent species in North America. Ungainly on land and graceful in the water, they generally weigh 40 pounds, live up to 24 years in the wild and are monogamous. They can stay underwater for 15 minutes without surfacing and sport a set of transparent eyelids that work like goggles. Beavers are also only second to humans in their ability to manipulate their environment, falling trees and weaving sticks to transform simple streams into complex mazes of dams and ponds. That quality has also put them at odds with agriculture, since they instinctively want to plug irrigation pipes at the sound of running water. 

But while some consider beavers a pest, scientists classify them as a “keystone” species for the way their handiwork protects biodiversity and creates food-rich habitats for fish and wildlife. “Most people don’t see all the burrowing they do to help sustain the ecosystem. It moves water around and allows organic matter to settle in. Because if there’s no food, there are no fish.” 

Gilmore has always loved beavers but jokes she was “in the closet” about it until she witnessed beaver impacts on the watershed. “The drought of 2014, as catastrophic as it was, suddenly showed people in the valley that where there were beavers, there was water.” This observation triggered a fundamental change in the Council, which had been around since 1992. “We suddenly went from supporting other people’s work to doing our own work, and that came because of our interest in beaver dam analogs and what they could potentially do for Scott Valley,” explains Gilmore.

Beaver dam analogs are an instrumental part of the Council’s new efforts. In a nutshell, these are a human interpretation of a beaver’s dam. Humans fall the logs, pound them upright into the streambed, and weave a lattice of willow between them. Like beaver dams, the analogs help divert flows and trap sediment, thereby rebuilding the streambed and recharging groundwater. Analogs are one of the fastest-growing stream restoration techniques in the West, and the Scott River Watershed Council was the first to embrace them in California. “Every year we go out, acting like beavers and filling the holes, and we can see a response in the ground water table in 24 hours. It’s a win-win for the ranchers, too.” 

Gilmore confesses the first couple of years were a steep learning curve. “We were really just thinking this was a little local project where we do some habitat and look at the science, but it ended up thrusting us into this state quagmire of social and permitting issues around beavers. We weren’t really prepared for it mentally, emotionally or financially. But now, we’re involved in the permitting process at a state level.” 

In addition to helping interface between ranchers and federal agencies, the Council is also at the forefront of pushing federal policies toward adaptive management. “There’s this whole idea that as humans we’re going to build it and walk away, but adaptive management means having an ongoing relationship with your project sites. We do something, the system responds, we adjust,” Gilmore explains. In this way, the process reflects the natural ebb and flow of the environment. “Part of the problem is that most water systems have gotten so locked in because we built our house here and a road there so the creek can’t change course. That has super negative consequences for the biological habitat.”

To date, 22 beaver dam analog structures have been built at seven sites in the Scott River basin. Beavers have been active, or have taken over nine of the structures, and most of the locals, including ranchers, have a largely positive view of beavers and dams, according to Gilmore. “It’s been interesting to discover where this tool works in our system and where it doesn’t. But now I’ll get ranchers calling and saying, ‘Hey Beaver Lady, I’ve got a beaver.’ When I offer to come over and cage it they tell me to wait. They say, ‘First, let’s just see what he does.’”•

Scott River Watershed Council