Beavers are Eager to Help Us Restore Our Watersheds

There’s a growing movement across Oregon to encourage beavers to return to our streams and rivers

By Scott Laird

The state of Oregon has a unique relationship with a local rodent. Beavers were here when the first white men moved across the wild and untamed territory in the early 1800s. They’re Oregon’s state animal, the mascot of our largest university, and hold a prominent place in the center of our state flag. We even call ourselves the Beaver State!

After almost being completely eliminated from North American rivers and streams during the 1800s, today wildlife biologists are recognizing the numerous benefits beavers provide in the areas they colonize. Oregonians have also begun to appreciate their beavers more in the last several years, especially the way beavers can help the Northwest’s struggling salmon populations.

But it’s a love/hate relationship, especially in some parts of the state, because beavers, while known for their industrious nature, have a tendency to cause trouble when they get to work. As we all know, beavers build dams, and dams control and constrain water. Done in the right location, beaver dams can produce great benefits – improving water quality, expanding fish habitat, providing water storage for agriculture, and saturating and recharging natural water tables. But, construct a dam in the wrong place, and a beaver can be more than just a nuisance – they chew down valuable trees to build their dams, create wetlands where they didn’t exist before, often cause flooding that damage farmland and residential property, and block culverts causing damage to roads.

So, how do we as Oregonians, living in the Beaver State, find ways to coexist with these neighbors, and encourage their proliferation so we can reap the many benefits they can provide? That’s a question many Oregonians, including those working in the Nehalem River watershed, are trying to answer.

Creating Beaver Dams

The rest area on the Sunset Highway, west of Timber Junction, was a convenient meeting spot. It was the middle of April, 2019, so the weather was cold, damp, and overcast, with an ever-present threat of rain showers, and most of us wore several layers of warm clothing.

Our trip was organized by Upper Nehalem Watershed Council (UNWC) Executive Director Maggie Peyton and included staff members from Oregon Department of Fish and Wildlife (ODFW), several other directors of regional watershed councils, and a few interested citizens.

The April weather didn’t seem to bother Steve Trask, our leader for the day, who wore just a down vest over a t-shirt, jeans, and rubber boots (he later gave in and added a flannel jacket). Trask would guide us into the Tillamook State Forest to inspect Beaver Dam Analogue (BDA) structures he installed the previous summer on several small streams located on Oregon Department of Forestry controlled lands.

Steve Trask during BDA field trip in April 2019.

Trask, who lives in Alsea, Oregon, operates Trask Consulting, Inc, a company that works with local partners to develop and install stream restoration projects in the Coast Range and the Willamette Valley. He is lean and rugged looking, and well spoken. You can tell he’s smart and capable, and he sports unusually tanned arms and face for April in Oregon – you can tell this guy spends a lot of time in the outdoors.

BDAs are man-made dams designed and constructed to replicate naturally built beaver dams, with the intention of encouraging beavers to repopulate a specific area. This new restoration technique is starting to be used across the country, often with very successful results.

Beavers are considered a keystone species – a plant or animal that plays a critical role in how an ecosystem functions – a species which would drastically change that ecosystem if it were removed. Beavers tend to live where they have good access to their preferred foods, which include the bark and twigs of willows, alder, and other deciduous trees, as well as ferns, grasses, blackberries, aquatic plants, and agricultural crops, but they’re also pretty adaptable. They live along rivers and small streams, in ponds, marshes, and lakes, and even ditches that have a year-round water flow. If they don’t have deep enough water available, beavers will build dams across a water flow to create their own water impoundment, using nearby trees.

Beavers build lodges in their ponds – mounds of branches and logs plastered with mud that have underwater entrances. They also dig dens into stream banks, and under logs or stumps.

Beavers breed between January and March and litters of between one and eight kits are born between April and June. Kits generally live with the adults for two years and then head off to mate and start their own colonies. Colonies usually contain one breeding pair of adults and recently born kits.

At an average size of 40 pounds, beavers in Oregon only have a few predators, including bears, coyotes, and cougars. They generally live for five to 10 years in the wild.

The benefits of beaver dams on streams can be profound. Their dams slow the flow of water in streams, and cool it down in the process, creating enhanced habitat for fish and drinking water for other species, especially in dry summer months. During heavier winter flows, beaver ponds provide shelter for both adult and juvenile fish. They help control flood conditions during severe rainfalls. They also recharge ground water supplies.

In August 2018 Trask Consulting was hired by the UNWC to work on a pilot project to install 27 BDAs on four different streams in an attempt to encourage beaver repopulation and influence coho salmon recovery in Oregon’s Coast Range.

The BDAs Trask and his crew constructed in the Tillamook Forest involved pounding in a row of vertical, nine-foot lengths of Douglas fir, ranging in diameter from five to 12 inches, across a stream. The posts are then interwoven with vine maple or Doug fir limbs. Ideally the BDA will catch more debris flowing downstream, retain more water, and will provide a prime location for beavers to naturally colonize, and maintain the dam the humans started for them.

At many of the installation sites, Trask left food caches, constructed cover and denning opportunities, and removed trees to provide sunlight to willow plantings, in order to encourage beaver colonization.

Trask explained that prior to the installation of the BDAs, an assessment was made of stream reaches in the region, looking for potential sites. Those identified sites were then “ground truthed” to show evidence of a historical beaver population in the area. Other criteria that make good BDA sites include a series of low terraced stream profiles and confining hillslopes that will easily create a floodplain and develop into a pond behind the dam.

Because this is a pilot project, the hope is to answer several questions:

  • Will beavers naturally colonize an area if a BDA is installed?
  • How effective will different BDA designs be?
  • Will human installed BDAs provide winter habitat for salmon even if beaver don’t colonize a BDA site?
  • Does the installation of BDAs improve the survival rate of salmon?

Trask led us to several BDAs on one creek, took us to see a large natural beaver dam at another location for comparison, and then took us to see several more installations on a different stream.

The results of this BDA project are mixed, but after just nine months and one winter, it’s still too early to tell just how effective they will be.

Beaver Believers!

Interest in beavers and their impacts on ecosystems has been growing during the last several decades, and has really accelerated in the last several years, particularly in the Pacific Northwest.   The search for more ways to effectively restore salmon habitat has been one of the main reasons, as fish counts of returning salmonids continue to fluctuate. Watershed councils and conservation groups have focused efforts on improving fish passage in streams by replacing impassable culverts, but those projects are often very expensive. Recently they’ve been enhancing fish habitat through the placement of large woody debris back into streams, after years of humans purposely clearing waterways. The large logs slow the stream flow, create pools and hiding spots for fish, and most importantly, capture mobile gravels that lift the stream channel back up to its historic flood plain.

There seems to be little question that beavers, and their dams and ponds, have historically been beneficial for salmon. They obviously have successfully survived together in the same streams for centuries – a recent bumper sticker may have said it best – “Beaver taught salmon to jump.”

That being said, some wildlife biologists and fish passage experts have retained a healthy skepticism about reintroducing beavers into known salmon bearing streams.

Greg Apke is the state-wide Fish Passage Program Coordinator for ODFW who took part in our BDA tour led by Trask. “In my role I get to see projects across the whole state,” said Apke at the start of the tour. “Beaver Dam Analogues have become the new restoration tool, not just here in the Nehalem basin, but particularly on the east side of the state. We’re seeing hundreds of these being applied. I have a lot of faith in Steve and he has a perspective I don’t have, so when Steve talks, I try to listen. I’m not an opponent, because I think these are wonderful treatments. But my perspective is more state-wide, and I’m really concerned that, while these projects have good intentions, they may, in some areas, have some implications that folks aren’t thinking about.”

Beavers and humans have a tendency to populate the same areas. “We both like low-gradient, fertile river valleys,” says Ben Goldfarb, an environmental journalist with a master’s degree in environmental management. “That’s where we’ve built our towns and our farms and our infrastructure. Today, we’re occupying a lot of the habitat that beavers would like to use.”

Beaver, Castor canadensis

And like humans, beavers like to modify their environment, which can lead to conflicts between the two.

In 2018 Goldfarb published Eager, The Surprising, Secret Life of Beavers and Why They Matter, a book documenting stories of beaver habitat restoration and beaver relocation projects across the United States, and even in Scotland. Goldfarb talked with beaver activists, including wildlife biologists, hydrologists, environmentalists, and beaver trappers, and explores how they are all working together to develop unique, non-lethal strategies for dealing with troublesome beavers that come into conflict with humans. Goldfarb talked with several consultants who, like Steve Trask, are working to restore beaver habitat. He examines in detail a very successful project on Bridge Creek in Oregon’s John Day River Watershed that has been ongoing since 2007.

According to Trask there are currently no efforts to quantify beaver populations in Oregon. “Biologists that spend a lot of time in the field, like myself, agree that beaver have severely declined in the Coast Range. This is strictly anecdotal, and based on a reduction in the number of beaver dams observed during stream inventories,” said Trask.

When beavers and humans come into conflict here in Oregon, there are several options on how the situation can be handled. One recourse is to try and remove them. Beavers on private land are considered a Predatory Animal under Oregon statutes, the same as coyotes, rabbits, and other rodents who may be destructive to agricultural crops and activities. If a beaver dam is causing localized flooding, a landowner can remove a dam, although ODFW does not recommend it, as it is usually futile because beavers will quickly rebuild, sometimes overnight. The removal of a lodge is also not recommended, and does require a permit from ODFW. It is illegal to move a beaver in Oregon without a permit from ODFW. Lethal control is recommended as a last resort and private landowners may lethally remove a beaver without any type of permit.

One successful technique Goldfarb explores in his book, is the installation of “flow devices” that can’t blocked by beavers and allow water to pass through dams and reduce water levels so flooding does not occur.

Goldfarb notes that a nationwide network of beaver enthusiasts has emerged, calling themselves “Beaver Believers,” sharing information, tactics, and contacts. A feature documentary The Beaver Believers, released in 2018, has recently been making the rounds of Oregon communities and receiving rave reviews. At a recent meeting of the ODFW Board of Commissioners in St. Helens, I spoke with Danielle Moser, Wildlife Program Coordinator for Oregon Wild, who told me numerous people in Salem involved with wildlife issues are currently talking about beavers. “It’s the hot topic right now,” she said.

The Beaver and the Salmon

Historically it is believed that the North American continent was once home to several million beavers. Lewis and Clark continually mention them in their journals from their epic journey in 1804-05, noting the large trees the beavers cut down, and their success in hunting them for food. Even before Lewis and Clark, beaver pelts were a valuable commodity, as they were turned into felt for hats, and were highly sought-after. Europeans started harvesting North American beavers almost immediately upon their arrival in the new world – as early as the mid 1600s. Later trappers moved across the plains and into the Rocky Mountains, harvesting beaver pelts everywhere they went. The British controlled Hudson’s Bay Company, who shared joint occupation in the Pacific Northwest and the Oregon Territory with the fledgling United States, decimated beaver populations south of the Columbia River in the 1800s; in 1875 alone the Hudson’s Bay Company traded 270,000 beaver pelts. Beavers were cleared by trappers from streams and rivers across the west, and when farmers and ranchers, and then loggers, moved in behind them to settle, the beavers were not made any more welcome.

The settlement of the continent and the elimination of the beaver’s habitat by cutting down forests and filling in wetlands, then replacing them with farms, as well as the continued removal of the beavers themselves, transformed the American landscape. Wherever beavers colonized they altered the geography, the hydrology, and the ecology. Remove the beaver and over time things changed from a fully functioning ecosystem to one that doesn’t support as much biology. Including salmon.

The fates of beaver and salmon have long been interconnected. Both are the subject of many Native American legends, hold an important place in native culture, and feature prominently in Pacific Northwest native artwork. According to native traditions, Beaver is a builder who symbolizes creativity, creation, cooperation, and harmony. He teaches people to be productive and persistent, and work in harmony with their surroundings. Salmon are sacred to Pacific Northwest native tribes and helped shape their culture, diets, societies, and religions. Both have struggled to flourish in a developed western landscape.

The reasons for the decline of northwest salmon is multi-faceted but can be traced to several major sources – all man-made. The over-harvest of salmon began in the early 1900s until the historically gigantic salmon runs were depleted. The introduction of hatchery bred fish, initially introduced to increase numbers, have instead weakened the gene pool. The installation of hydroelectric dams across northwest rivers, the original renewable energy source, also block fish passage and have played a big part in their reduced numbers. The loss of forest habitat and changes to the streams where they return to spawn every year, and where their hatchlings begin their life before migrating out to sea, has contributed to their decline.

The 1980s saw the beginning of efforts to address the declining fish runs. Under the Endangered Species Act, recovery efforts have brought together many diverse interests. That has included local watershed councils who have been at the forefront of habitat restoration efforts.

The beaver’s road to recovery has taken a different path. Starting in the early 1900s a combination of natural resource agencies across the country began reintroducing beavers into their lakes and streams. Laws protecting beavers from trapping allowed them to multiply. Efforts in New York state, which had just a single colony of beavers left within their borders in the 1890s, saw their beaver population explode to 15,000 by 1915. Beavers saw similar success in other places across the country. But as beavers returned to their former haunts, they found a changed landscape, now inhabited by humans. And that’s when the problems started. As beavers moved back into areas they had historically populated they found they had to share those areas with highways, railroads, farms, ranches, drainage ditches, and suburban sprawl.

Salmon recovery efforts have led wildlife biologists and others working in the field to recognize the connection between salmon and beavers and how their fates are intertwined.

If You Build It, The Salmon Will Come     

Back in the Tillamook State Forest with Steve Trask this April, we get to see the early results of the UNWC’s BDA project, which hopes to encourage beaver colonization, and as a result, help more salmon survive and return to Oregon each year.

Trask has spent many years surveying streams in the Coast Range and Willamette Valley. He has spent a good portion of his career studying coho salmon and what they need to survive and prosper – he has snorkeled through almost 13,000 miles of streams and salmon habitat. “It’s really helped guide me in making restoration decisions,” he told us at the start of our tour.

Trask says the main stem of the Nehalem River has “serious temperature issues” in the summer across most of its entire 120 mile length – salmon have difficulty surviving in temperatures above 75 degrees and the Nehalem River recorded temperatures of up to 85 degrees last summer. Trask says tributaries, and particularly headwaters of rivers, are generally cooler, and provide important refuge for salmon. Beaver dams help keep that water colder for a longer period of time. “Beaver Dam Analogues can help expand the production potential of these headwater streams that are naturally steeper and more narrow, and where the fish habitat and pool areas are smaller,” explained Trask.

Having worked in the region for several decades, Trask says the specific sites he chose to install BDAs for this project in the Coast Range show historical use by beavers, even as recently as the 1990s, but today those populations have decreased for unknown reasons. There were no functioning beaver dams on any of the four stream reaches where this pilot project constructed BDAs. The sites tended to be high in the headwaters of the basin where the habitat itself isn’t ideal for providing rearing habitat for young salmon. “The benefit of a BDA in these locations is exponential when you put it into a location like this,” says Trask.

Beaver Dam Analogue

Of the 27 BDAs installed by Trask, three had already been colonized by beavers after just one winter. Five that were not colonized by beavers were functioning as if beavers were there, with four of those showing enough of an increase in water level to be considered a success. Of the 24 BDAs that were not colonized, six had a new, natural beaver dam built above the BDA post line, an occurrence frequent enough to suggest a significant causal relationship to the BDA, said Trask.

One site we viewed on Rock Creek was fully functioning and showed signs that beaver were living in the pond, they just weren’t actively adding to the BDA. “You can see all the alder that was growing here has been gnawed off. They’ve adopted this site, they’re here, but they’ve decided the dam is good enough and they don’t need to maintain it,” explained Trask.

At the sites we viewed, Trask noted that in summer, prior to installation of BDAs, these small streams in the headwaters would be reduced to just a trickle, with very small pools of water that don’t have the capacity to rear juvenile salmon. “But a successful BDA will create a pool that will stay full much later into the summer and provide an incredible amount of rearing area,” says Trask.

To show the impact of installing BDAs, Trask said the seven sites that are functioning have the potential to produce an additional 1,830 coho smolts that would survive to escape to the Nehalem River – which is more than one of these entire small creeks was currently producing. On average, of those 1,800 smolts, about 114 adults would survive to return to the creek to spawn.

According to Trask, last year a total of about 5,000 coho salmon escaped from tributary streams to the Nehalem River. Based on historical cannery records it had been about 130,000. The best year in the last 20 years showed escapement of about 30,000. “The goal he

re, with these BDAs, is to increase productivity so in those good years when conditions are right in the oceans and river temperatures aren’t too bad, we have coho getting out of the Nehalem and into the ocean,” says Trask.

Bringing Beavers Back to the Beaver State

As part of our tour, Trask took us to visit a massive natural beaver dam on a small unnamed tributary of Rock Creek, built from large old growth trees that survived the Tillamook Burn. When those trees eventually died and fell across the stream, beavers moved in and built a dam against them; they also utilize the old trees in the area as cover from predators. The site had numerous meandering side channels, a wide and deep pool, and the land below the site was wet and spongy to walk on due to saturation. Trask said when he previously snorkeled this stream they counted 10,000 coho. “It’s just a mega producer,” says Trask. “And that was when we realized that all these little headwater streams that are just three and four feet wide have beautiful gravels and nice cold water, but it’s really the beaver that expand the potential by setting up shop and staying here for the long term.”

Beaver Dam Analogue seen during April field trip.

After viewing one of the BDAs, Apke, ODFW’s Fish Passage Coordinator, had this to say: “The Department does not consider natural beaver dams as an impediment to most fish species. Pacific salmonids have been co-evolving with beaver for a long, long time and we certainly have distribution of native fish above beaver dams on the record.” He noted that fish passage in specific locations can be a complicated issue that involves knowing what types of species use a stream, the time of year passage might need to occur, the ability for juveniles to navigate in the stream, and what other native fish need passage in those streams.

While the results of this initial pilot project might seem limited, we need to keep in mind that many of the designs implemented were experimental with the intention of seeing what works and what doesn’t work. Trask is extremely pleased with the results he is seeing and the success rate of the BDAs after just one winter. The seven successful sites produced an average lift of the stream channel of 9/10 of a foot. Trask learned that posts woven with fir branches were more likely to succeed in impounding debris and water than those where vine maple branches were used. In several locations there were salmon fry where they had not been seen before.

This summer the UNWC will once again work with Steve Trask and install another set of BDAs.

Apke says he still needs to see proof that BDAs work in Oregon streams before he can completely get behind them. “I’m fully supportive of these pilot projects and the science that we’re going to learn from the reporting we get,” says Apke.

Could a large rodent be the answer to a number of tough questions we, in the Pacific Northwest, are searching for – how to save the salmon, how to replenish our water tables, how to slow down fast moving winter streams? Hopefully Steve Trask, Maggie Peyton and the UNWC, and other beaver believers around Oregon can help us find out.

“The recovery of beaver is the number one attainable solution for restoring ecosystem function in Coast Range watersheds,” says Trask. “It’s really less about the recovery of salmonids than it is about restoring the functionality of the aquatic systems where salmon spawn and rear. Beaver, as a keystone species, are more important to the recovery of ecosystems than probably any other single species.”

This article was originally published in the Vernonia’s Voice issue on 6/6/19 and is used here with permission from the author.