The hay fields in summer were lush and green, and heavy rains had broken the beaver dams on David Trew’s farm. When I called to get directions, he tried to convince me not to come. “Not sure if you’d still be interested,” he said. But of course I was; change was the whole point. Trew’s hundred acres lay along the Mora River, about an hour’s drive over the mountains from Taos, New Mexico, in an isolated valley settled by Spanish colonial farmers before the U.S. public land survey. The long, thin parcels are stacked perpendicular to the river, oblivious to the national grid. Mora was a pocket of resistance in the Mexican-American War and, a century and a half later, the first U.S. county to ban oil and gas operations, starting a nationwide movement. 1 They do things differently here.
I was beginning a road trip through the Mountain West, studying the return of the North American beaver, which has lately gained something of a cult reputation as an environmental engineer. 2 I had heard stories about humans and beavers working together to restore wetlands and river systems, and I wanted to see for myself. That might sound weird — working together — but as a landscape designer you have to be open to unusual collaborations. 3 If farmers and ranchers were turning into “beaver believers,” I could respect that.
When beavers returned to the Mora Valley, David Trew harnessed their activity to bring more water to his farm.
I drove past a small Catholic church, down a dirt road, across the river shrouded by coyote willows, to reach the farm that Trew manages. A thin irrigation ditch had overflowed, inundating the hay fields. Agriculture is complicated in Mora. The valley gets about 22 annual inches of rain and snow, more than twice the state average, but it falls unevenly. Between the spring snowmelt and the late-summer monsoons, there are dry spells, and farmers draw water from the river through community-managed acequias, an intricate network of historic canals.
Growing up in the parched Texas Panhandle, Trew had helped his family experiment with water harvesting techniques that produced eight new live springs on their ranch. 4 So when beavers moved to his part of Mora Valley, he decided he would leave their dams undisturbed and observe the impact on the land. In that first season, the river held more water late into the summer and fall, and groundwater levels rose. High pressure drew water upslope to seeps and springs that had been dry for years. That gave Trew the idea of harnessing the beavers’ activity to bring more water to the farm. To keep the dams from getting out of hand and flooding his fields, he installed a pond leveling system known as the “beaver deceiver.” Invented by wildlife conservationist Skip Lisle, it involves a caged pipe placed upstream of the beaver dam, so that water rising above a certain level flows into the pipe to be released downstream. 5
Left alone, beavers modify the environment more extensively than pretty much any other animal — except humans — and they fit their designs to the site context. Sometimes they build a single dam and maintain it for years. Elsewhere they create dozens of structures, shaping a watery world of ponds, shallow wetlands, and meadows. They eat the leaves, buds, and inner bark of trees, preferring soft woods — aspen, poplar, cottonwood, willow, alder, birch, maple, cherry — though they are highly adaptable and will use other species, too. And, of course, they fell trees and bring the logs and cuttings back to their home pond to build dams and lodges, using rocks to stabilize the bottom and sediment to strengthen the walls. Beaver dams can be as large as ten feet tall and 1,500 feet long, but in the small tributary streams where I did my field research, they were typically ten to 30 feet long. I saw deep, well-established ponds up to an acre in size, usually with a lodge in the middle.
Ahead of my trip to the Mora Valley, a monsoon had caused flooding that breached the two main dams on Trew’s farm. But while the failure of a beaver dam is violent and destructive, it is part of a cycle that makes hydrologic systems more resilient. The sudden rush of water produces wider, braided streambeds and meanders, and it renews the meadows with sediment and nutrients. After checking out the broken dams, Trew and I walked a half mile upstream to see the beavers’ reconstruction project, where they were building a series of weirs to slow the current so they could build a new main dam. We counted about ten of these smaller structures, at intervals of 50 to 100 feet along the river, and we saw young willow shoots growing in the hay field, twenty feet from the bank, indicating that the groundwater had expanded to effectively double the river’s width.
While the failure of a beaver dam is violent and destructive, it is part of a cycle that makes river systems more resilient.
Later, on the walk back to my car, we passed one of the 17th-century acequias, and Trew explained the complexity of settlement in the valley. If the beavers are new here — or new again — so are many of the farmers. Mora County has some of the state’s least expensive irrigated cropland, and when Trew arrived in 2007 it was rapidly being developed; the number of farms and ranches had grown by 44 percent in five years. 6 The gravity-fed acequias create a shallow wetland network across the valley — a novel ecosystem in its own right — but the open ditches are less efficient than pipes and culverts, and in the current climate there is not enough water to go around. 7
Trew wondered whether the destruction of the dams on his farm might have been helped along by a vandal with a crowbar.
With the river at their front door, Trew has encouraged his neighbors to lessen their reliance on the acequias by using natural surface and groundwater flows. He sells organic hay at a premium as specialty feed, and he talks up the economic benefits of managing the land holistically. But not everyone has come around to his point of view. Some of his neighbors see the beavers as pests and say the ponds invite mosquitos and floods. Trew wondered whether the destruction of the dams on his farm might have been helped along by a vandal with a crowbar.
As I left the farm, I thought about the how the hard lines of the acequias and the braided, shifting stream channels offered a contrast between two ways of thinking about a landscape over time. Destruction, abandonment, and renewal are so important to the beavers’ cycle, and to the way they build and inhabit space, which is contrary to human values like linearity and constancy. Adaptations like Lisle’s pond leveler have helped the two species live side by side, but if people and beavers are truly going to work together to restore water systems in the Mountain West, there will need to be a greater reconciliation.
Once hunted nearly to extinction, North American beavers have recovered to a population of about 10 to 15 million. That sounds impressive, until you realize that they were once ten times as numerous. Before the colonial fur trade, beavers outnumbered humans and played nearly as big a role in shaping the environment. 8 Still: imagine how many millions of beaver dams are out there right now, occupied or abandoned, on the back acreage of untended fields or in steep, hidden valleys. Subversive animals are rewriting the landscape, changing its topography, without hardly anybody registering the change.
Subversive animals are rewriting the landscape, changing its topography, without hardly anybody registering the change.
There is no map of beaver habitat. Many people I talked to on my tour across the dry Colorado Plateau were surprised to learn there were any wetlands around at all. I called ecologists and state land managers to identify potential beaver building sites, and I pored over aerial images looking for clues. Heading north on Highway 84, through a national forest named after the fur trapper Kit Carson, I pulled over to check out a beaver lodge I had spotted on Google Earth along Canjilon Creek. It was a bust. The lodge had collapsed, probably months ago, and the pond was a puzzle of cracked mud and sand.
I camped that night among the magnificent mesas at Georgia O’Keefe’s Ghost Ranch, listening to a thunderstorm and thinking about flash floods. 9 Collectively, beavers may have a large impact on the land, but individually their efforts are easily erased. Before we compare their works to those of landscape designers or engineers, we have to acknowledge the differences in scale. Starting around the turn of the 20th century, the hydrology of the American West was dramatically altered by the Bureau of Reclamation and the Army Corps of Engineers. How did O’Keefe feel when the Army Corps diverted a river and flooded 5,000 acres to create the Abiquiu dam and reservoir near her ranch? Built in 1959, for hydroelectricity, water supply storage, and flood control, the reservoir was the result of a flawed technocratic imagination; it has never been fuller than 30 percent capacity, and lately that figure has been closer to five. 10
Before we compare beavers’ works to those of landscape designers or engineers, we have to acknowledge the differences in scale.
More recently, designers have proposed (and sometimes built) site-specific landscape infrastructures, adopting a “living systems” approach that embraces nature’s dynamic fluctuations, incorporates living materials, and even employs other species as agents of change. 11 Meanwhile, land managers coping with drought and climate change have sought ways to retain local water efficiently and cheaply. Here beavers make their star appearance. Across North America and Europe, public agencies and private actors have reintroduced beavers through “re-wilding” initiatives. In California and Oregon, beavers are enhancing wetlands that are critical breeding habitat for salmonids, amphibians, and waterfowl. In Nevada, Utah, and New Mexico, environmental groups have partnered with ranchers and farmers to encourage beaver activity on small streams. Watershed advocates in California are leading a campaign to have beavers removed from the state’s non-native species list, so that they can be managed as a keystone species rather than a nuisance. And federal policy is shifting, too. The U.S. Fish and Wildlife Service sees beavers as “partners in restoration,” and the Forest Service has supported efforts like the Methow Beaver Project, which mitigates water shortages in North Central Washington. Since 2017, the USDA Natural Resource Conservation Service has funded beaver initiatives through its Aquatic Restoration Program. 12
Ecologist Glynnis Hood, at the University of Alberta, set the stage for much of this work in her 2011 cri de coeur, The Beaver Manifesto. “We drain a landscape; beavers build a dam and bring the water back,” she wrote. “There is something in that persistent drive to sustain water on the landscape that is a clue for our own survival as a species.” 13 In a way, beavers are the perfect companions for a D.I.Y. generation of design-build enthusiasts. “No other species do what beavers do, except humans,” Hood told me. “They are extremely adaptive.” When I mentioned that I was surprised to see beavers making sagebrush dams in Utah, she noted they have been known to use PVC pipes, rocks, and even beaver skulls. They are an urban species, too, taking up residence not just in pastoral suburbs but in cities like Vancouver, Calgary, Pittsburgh, and New York City. In Berlin, officials built a floating river platform to provide a “rest stop” for beavers swimming through an area where the embankments are completely hardscaped. 14
How are water rights affected by a beaver dam? How is risk managed? These are social and political questions.
Hood helped me see that restoring beaver habitat is not just an ecological challenge but a social one. When beavers modify the environment through their constructions, the effects are felt downstream, outside wetlands and other conservation areas. 15 How are water rights affected by a beaver dam? How is risk managed? These are social and political questions. In fact, when the Scottish government started a beaver reintroduction program, it hired sociologists to work alongside ecologists. 16 People complain that beavers are destructive, they’re unpredictable, they cause flooding. These things are all true. Living with such a willful species requires careful negotiation. Humans have to recognize the ecological benefits beavers bring, and be willing to give up some control.
Continuing my field research, I met Dr. Rory Cowie, a hydrologist who once held the position of “Town Beaver Monitor” in Telluride, Colorado. The community was so proud of its beaver pond (and yet so eager to build housing) that they hired Cowie to install flow devices so they could keep the pond from flooding million-dollar real estate along the San Miguel River. Cowie is now a research director at the Mountain Studies Institute, and he works with the U.S. Environmental Protection Agency to remediate highly polluted mining sites in Southwestern Colorado. He took me to see contaminated wetlands along the Animas River, where human access has been restricted since the last mine closed in 1991. Left alone for three decades, beavers have created extraordinary pond systems, filling entire valleys with water from side to side. Cowie believes those wetlands could help remediate heavy metals and other mining waste without fuel-intensive processing plants, and he’s trying to convince the EPA to back a study. As we watched a moose wade across the saturated valley floor, Cowie noted that beavers rarely get credit for creating the habitat that has made Colorado’s public lands a magnet for tourism. Everyone sees the moose, he said, but no one sees the pond, or thinks about how it got there.
Our cultural ideal of the stream as a thin blue line is so different from the streams where beavers live: wide and sinuous, with irregular emergent zones.
Beavers live where they are allowed: at ecological restoration sites, behind game fences that keep out grazers like cattle and elk, or on inaccessible land with low value to humans. Visiting these places, I began to understand our collective image of a stream — that thin blue line on maps — as a cultural construction that emerged after the fur-trade era. It is so different from the streams where beavers live: wide and sinuous, with irregular emergent zones. As European settlers moved west in the 18oos, the beavers were already mostly gone, their swampy mazes dried up. Homesteading pioneers found narrow, fast-moving streams without ponding or marshes, and they went on to build irrigation ditches, dams, reservoirs, farms, cities, and open grazing lands, which have completely transformed riparian systems. But it was the removal of beavers that turned those streams into lines in the first place.
A week later, I was bumping along a washboard road through Utah’s semi-arid canyonlands toward the Moonshine Wash research site on the San Rafael River. From a distance the river seemed a lush oasis, a green ribbon fringed by willow and cottonwood, winding between brown and red dunes. But up close the view was bleak, dominated by dead tamarisk bushes killed by beetles the state had released to limit the spread of the invasive plant. With the tamarisk under control, the state uses this stretch of river to test watershed restoration practices, in partnership with the federal Bureau of Land Management and Utah State University.
At Moonshine Wash, researchers have built ‘beaver dam analogs’ to test the effect on stream meandering and vegetation.
One of the researchers on that project is Wally Macfarlane, an associate in Dr. Joe Wheaton’s Ecogeomorphology and Topographic Analysis Laboratory at Utah State. They’ve taken a literal approach to the prospect of animal collaboration, building “beaver dam analogs,” or BDAs — post-and-wicker-weave dams that mimic the function of natural beaver dams — in order to test the effect on stream meandering and vegetation. In some cases, they’ve managed to attract local beavers to adopt these BDAs, or to build natural dams nearby. In other cases, they’ve relocated beavers from elsewhere to repopulate a watershed. Macfarlane said the goal is to design restoration projects that are process-oriented and self-sustaining, and ultimately maintained by the beavers themselves. He claims their methods could be used to revive degraded wetlands and streams at a tenth the expense of conventional restoration, which costs an average of $130,000 per mile. 17
Macfarlane said that when he leads restoration workshops for landowners, he asks them first to draw a river. They draw the same straight blue line, and they are surprised when he shows them photos of a more complex, multichannel system. Beavers drag logs through streams and ponds, creating complex textures in the land surface. The water pressure behind dams causes micro-scale erosion, generating channels and ridges of different depths. All that mixing of materials and variability in environmental conditions creates niches for various animals and plants to get established, which enhances biodiversity and makes the system resilient to seasonal or climatic shifts. The channeled floors also improve groundwater recharge and retain sediment that would otherwise wash away. Over months and years, beavers intentionally manipulate the topography in ways that produce a richer food supply and source of building materials. In this sense, they are not just architects or engineers, but also farmers.
Over time, beaver activity produces a richer food supply and source of building materials. In this sense, they are not just architects or engineers, but farmers.
Macfarlane and I had talked by phone, and I thought I’d be alone at Moonshine Wash. But as I was standing at the rim, trying to figure out how to get down to the stream 40 feet below, I met a team of research ecologists out for the day to conduct plant surveys. I introduced myself to Justin Dolling of the Utah Division of Wildlife Resources, who pointed out the eight locations where beaver dam analogs were installed along the river. At each spot, 20 to 30 wooden posts were set in an arc from bank to bank, and branches were woven between them. Beavers on the San Rafael don’t typically build dams, Dolling said, because of the “flashy” nature of the landscape —its susceptibility to flash floods — and because of the ease of burrowing into the sandy banks. But researchers believe the BDAs could play a valuable role in stream restoration. The idea is that as sticks and dead grass build up along the posts during high water or flash floods, the water is forced around the side, eroding the steep and incised channel edge, and producing more varied channels of different depths for the water to flow through. This, in turn, enhances plant biodiversity and habitat for fish, insects, amphibians, and birds. 18
Once a successful wetland is established in the shallow, slow-moving water, it can expand up or down stream. Researchers can track those expansions and modify their dam-building techniques, as they observe and learn from beavers. Macfarlane said his team was recently inspired by beavers to start building dams without posts, by weaving wood with mud and clay. This works especially well in smaller streams with a lower gradient. They found that juniper is one of the best plants to use for this type of construction. It’s flexible, and the needles create a textured web for holding mud, and it can stay green for months in the water without rotting. It turns out that beavers are teachers, too.
Surprisingly, Macfarlane’s team does most of its restoration work with private landowners. While almost half the land in the 11 western states is federally owned and managed, about 70 percent of riparian land is privately held. Farmers and ranchers along designated waterways can get federal grants for stream restoration projects, and the 2018 U.S. Farm Bill added funding for low-tech methods like BDAs. Jeremy Maestas, an ecologist with the USDA Natural Resource Conservation Service, said that since the bill passed, his office has seen more inquiries from ranchers eager to find low-cost ways to keep their pastures green. Grants offset 50 to 75 percent of the capital cost of building these systems, and the agency also provides a design manual and technical assistance. 19
Beavers can also play a role in managing wildfire risk, according to Macfarlane. When Idaho’s Baugh Creek watershed burned in 2018, Wheaton’s lab joined a group of state, federal, and private partners to expand a previously planned restoration project. Surveying the area with drones, they found that the fire spared parts of the creek where beavers were active. Now they hope to recruit more beavers to accelerate the land’s recovery. In one week last fall, they installed 139 BDAs and “Post Assisted Log Structures” over 5.5 miles of stream, to stay ahead of snowfall and spring runoff. The BDAs should help retain water and sediment and minimize the loss of nutrient-rich material. 20
On a tip from MacFarlane, I ended my road trip at a Walmart parking lot in Logan, Utah, where a family of beavers lives between curbs and culverts, in the heart of the Cache Valley, named after the fur caches of 18th-century trappers. When Walmart built the store in 2006, it agreed to maintain existing wetlands without realizing they were ideal beaver habitat. At first the company tried to remove the beavers, but the animals kept returning, and with all the media coverage the company decided to accommodate them. Just past the edge of the parking lot, obscured by a dense stand of cattails, willows, and cottonwoods, the beavers and Utah State researchers have collaborated to build a rich infrastructure, including a lodge and pond, as well as culverts and a flow device to keep the water level stable. Perhaps this is the ultimate sign of the beaver revival, that they’ve adapted to living at the center of corporate America. 21
And we’re all adapting with them. Brett Milligan has framed climate change as “landscape migration,” or the “accelerated reshuffling of just about everything.” Environmental conditions are changing faster than any of us can comprehend. As Milligan observes, “This is the landscape medium in which we will design.” 22 Beavers can help us make sense of that reality. They design for change, in the most practical sense, and they try to slow things down, quite literally. (“Beavers go crazy at the sound of running water,” Cowie told me. Their instincts drive them to stop it any way they can.) As beavers are “reintroduced” to more areas, we should remember that we cannot restore historic conditions. We must conceptualize a messier future for landscape architecture, accepting new ecological relationships between plants, animals, humans, and infrastructure. 23
Could the beaver’s low-tech, idiosyncratic building techniques make a comeback in an era dominated by parametric algorithms and modular design systems?
Beavers have specialized knowledge, not only about water and its storage, but also about how to adapt and thrive in degraded environments, and how to nurture habitat for fellow species. Could the beaver’s low-tech, idiosyncratic building techniques make a comeback in an era dominated by parametric algorithms and modular design systems? 24 The landscape journal LA+ recently invited speculative design proposals reimagining a post-apocalyptic Central Park. Honorable mention went to OPSYS/Landscape Infrastructure Lab, which proposed to “decolonize Manahatta” by giving the park over to beavers. The animals’ work is “anti-parametric,” the designers wrote, “and more than anything exhibits the impact of time as a repetitive cycle on landscapes.” 25
After spending some time at remote restoration sites, it’s not hard to imagine that such proposals will eventually move from the pages of design magazines to the realm of built projects — or anti-projects. Can we imagine tearing down walls and fences to live more collaboratively with other species, to let them be active landscape agents? Can we accept their measures of success, which differ from ours? Will we be able to predict and anticipate their activities, or be comfortable not doing so? How will we deal with uncertainty and destruction? Would I allow beavers to live in my own backyard?
In my field research, I shifted constantly between scales and technologies. I used Google Maps to pin beaver sites to road networks, mountain ranges, and drainages; and I hiked with a sketchbook, camera, and aerial drone. I recalled the words of Swiss landscape architect Gunther Vogt: “The focus that alternates between far and near, that positions the details of the life cycle of the autumn crocus in a larger context, also discerns patterns in a landscape that remain hidden from the superficial gaze conditioned by personal and cultural habits of seeing and thinking.” 25
Standing in the Lawn & Garden section of the Walmart lot, near stacks of fertilizer and gallon jugs of Roundup, I brought my drone back to Earth and packed it away. I had covered 1,800 miles in 16 days, and I’d seen beaver designs that were as inventive and ingenious as great works of landscape architecture. From the dry mountains of New Mexico, to the western slope of the Colorado Rockies, to the red sandstone and sagebrush hills of Utah, I’d witnessed dramatic landscape changes in real time. Soon I would return to my normal life, family. On the drive to the airport, I thought about how the emergence of animal agency could invert the story of the American West. We need to create a new legend of interspecies cooperation, and end the pattern of dominance and subjugation.
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