What the Beaver Can Teach Us About Innovative Conservation

Engineering That Views Nature as a Model, Not an Obstacle

The man appeared suddenly, out of the darkness and around the bend. He was standing to the side of the asphalt, near the edge of the floodlights illuminating a barricade of orange traffic barrels and, beyond, a great pile of dirt disappearing into the night. Half of the mountain road was blocked off—was, in fact, no road at all past the barricade and the pile. I drove closer and slowed to a stop. As I did so the man made some unhurried steps toward my car. It was past midnight, late summer, in the northeast corner of California, where the Sierra Nevada peter out and the volcanic Cascade Range begins. 

My car windows were down. My radio already off. There had been no other traffic, no other living thing for an hour at least, aside from the oaks giving way to pines. The choking, relentless heat of the Central Valley had loosened its grip as the altitude climbed. I was headed to a meadow called Childs, just outside of Lassen Volcanic National Park.

In the meadow was something I wanted to see, a very particular type of dam—a series of dams, in fact. They were beaver dams, but they weren’t built by beavers. The technical term for these dams is beaver dam analogs (BDAs), and they were built by biologists, ecologists, and land-management experts. The previous autumn, these BDAs had been placed in a little creek named Gurnsey that winds through Childs Meadow, well before the snows filled the meadow and the spring melt flooded it. Now, I’d been told, it was a different sort of meadow—a bit marshy in spots, its soil spongy, the land undergoing a dramatic transformation back to a time before we killed off nearly every beaver on the continent. A more waterlogged time. 

The man—big, bearded, a florescent-green vest over his flannel—broke into a friendly grin as he neared. “Hope you’re not in a hurry,” he said. I told him I wasn’t. He stepped back a few paces and we let the buzz of the floodlights fill the silence for a minute until a crackle came over the radio clipped to his belt. “Lemme see how long this could be,” he said, then walked back to his post at the edge of the light. I could hear him talking with a crew that must have been farther up the mountain, at another stop for traffic heading down.

“Maybe 15, 20 minutes,” he shouted over to me. More time passed under the buzzing lights, my windows down, the man staring up the road at the big pile of dirt and whatever lay beyond. Finally, I cut my engine, and the man returned. “Not a lot of traffic on the mountain this time of night,” he said, waiting for me to explain myself, so I told him I was there to see a few beaver dams some folks had built. He looked up into the night sky for a moment, then asked me why they would do that. It was a good question, and I hoped to have an answer for him on the way back if I saw him again.

People were building all kinds of crazy things on these mountains, he said. This road, for example—and he gestured toward the looming pile of earth: They were widening it, straightening it, adding more buttresses; and they’d have to do it all over again one day, when the road again started sliding down the mountain. Was it the road sliding down the mountain, or the mountain sliding down upon the road? It was, of course, both. 

Just then a car’s headlights appeared. A moment later, a truck’s, then another truck’s, and soon a whole line of vehicles—a dozen or so—rumbled by, and just as suddenly the man began waving me on past the barricade and pile, through the construction zone, up the road, up the mountain, to see yet another strange human construction, this one arguably more useful and transformative than even a road. 

The people of the Haida Nation, of the northwest coast of North America, tell a story about the beaver. It begins with a young woman marrying a great hunter and traveling with him to his hunting grounds, far away from her people. They build a home, alone together in the wilderness. The woman becomes pregnant. The hunter goes away on his hunts but always returns. His hunts grow longer and longer: One night becomes two, two nights becomes a week. The woman is bored, so she takes up swimming in the pond by the cabin. Her husband is gone for ever-longer stretches, and she gets better and better at swimming and teaching her children to swim until the pond is too small for them, so she builds a dam out of branches and mud, expanding their pond. She then dams up another section of river, and another, creating a whole series of ponds. You see where this is going. 

One of the most important things the dam would be doing was trapping carbon in the murky, silty, slow river bottom behind it.

She builds a structure out in the middle of her original pond, the biggest pond, and this is where she now spends some time sleeping. Finally, her hunter-husband returns from his very long hunt. But he can’t find his wife. He searches all over until he decides she was probably eaten, and he sits down beside the big pond with the little island structure in the middle of it, and he weeps and sings a mournful tune as he remembers his wife.

As he’s singing, an animal swims up to him. The animal is furry, and it carries a stick in its mouth. Behind the creature are two more, smaller, also swimming, also carrying sticks in their mouths and chewing on them. The biggest of the three speaks to the man. “Do not be sad,” the animal says. “It is I, your wife, and your two children. We have returned to our home in the water.” 

I first encountered the Haida’s beaver tale in the book Beaver by Rachel Poliquin. “The legend gives voice to all that is captivatingly human and implausibly true about beavers,” Poliquin writes. Beavers are familiar, knowable, and domestic. They build homes—lodges—for their families. And they are, apparently, companionable. Fur trappers sometimes kept orphaned baby beavers as pets after murdering their mothers. The conservationist Grey Owl described baby beavers as “small and willing captives, with their almost childlike intimacies and murmurings of affection, their rollicking good fellowship with not only each other but ourselves … They seemed to be almost like little folk from some other planet, whose language we could not yet quite understand.” 

Perhaps the people building beaver structures were closer to an understanding of the little folk’s language. The next morning, after my drive up the mountain, at the Mineral Lodge Restaurant, I met Kristen Wilson, an ecologist at the Nature Conservancy and one of the overseers of the BDA project. Soon we’d be heading out to Child’s Meadow to see the beaver dams she was looking after. Over breakfast, she outlined the broader implications of the project. What I had to understand, Wilson said, was that something seemingly as simple as a small dam constructed out of woven willow branches, blocking up a thin creek, was not quite so simple.

The dam was meant to perform several tasks. A few of these, such as habitat restoration and water retention, were fairly obvious. But one of the most important things the dam would be doing was trapping carbon in the murky, silty, slow river bottom behind it. This task—carbon capture—was what paid for the dam’s existence. The BDA pilot project in Child’s Meadow had received the bulk of its funding via California’s cap-and-trade program, which in 2018 paid out $1.4 billion to fund a huge range of projects, everything from rebates for buying environmentally friendly cars and buses, or for solar panels, to grants for planting trees in urban areas, to simply buying up land to preserve and restore it. 

 

The BDAs were, Wilson explained, a newer and cheaper form of meadow restoration. The usual process of restoring a wetland in a meadow was simple construction: dig a pond, plug up the downstream end, watch the water fill it in. Pond-and-plug, it’s called. Of course, this requires some big machinery, but using big machines—engineering our environment—is something we are good at, and it results in a picture-perfect mountain meadow with a pond at its center. One problem with pond-and-plug is that it is expensive, easily four or five times the cost of BDAs, if not more.

The bigger problem is that it in no way replicates any natural process. Backhoes, it turns out, don’t have an ecological equivalent. So, while the pond in the meadow looks picturesque for a season or two, after four or five years the river has usually broken through or, worse, silted up so badly behind a concrete dam that the pond is no longer a living system. BDAs, by comparison, create “natural alluvial plains,” Wilson said. “They trap silt but don’t lock it up like a human-built dam. The silt sifts down, the amount changes with the seasons and rainfall, distributing a healthy but different amount of sediment throughout a region. It manages the soil, the water, the whole ecosystem.” 

Wilson is obsessed with rivers. She has studied them for years—photographing them, giving presentations about them, sitting silently next to them and just watching and listening to them move. And rivers, even little creeks, even arroyos that are dry most of the year, do move constantly, jumping banks, altering course, cutting new paths. We have this idea of how a river meanders, that perfect, serpentine turn.

“Why are we restoring our streams to the same line of beauty?” Wilson asked me. She handed me a napkin and asked me to draw out what a river should look like, and sure enough I drew a line, a repeating S. She looked at my drawing. “When you look at real rivers, not the textbooks, it’s not symmetrical. The bends are never perfect because nature is messy.” 

The server came by to drop off the check. “It was $18  even,” she said. “That’s good luck. Y’all should buy a lotto ticket.” 

Wilson, still staring at my meander drawing, finished her thought. “What you’ll see, out in the meadow, isn’t going to look like the ideal vision of a mountain meadow. It’s chaotic. But it needs to be that way. In the chaos is opportunity.” 

Nature is a problem we can’t engineer our way out of. But, like the beavers, we might engineer our way back into it.

To reach the chaos, we had to squirm carefully under a barbed-wire fence, then take a long walk across the open plain of the browned meadow, until the creek revealed itself. On the walk out, we’d seen what appeared to be a Cooper’s hawk in the distance, and Wilson stopped. When she’d been out in the meadow the day before, she’d watched a pair of sandhill cranes defend their young from a golden eagle, and she worried over 

the cranes. She wanted to make sure the eagle hadn’t returned. Once she’d confirmed the hawk was a hawk, and that it wasn’t near where the cranes were nesting, we pressed on. The ground grew muddy long before we reached the overgrown creek bank, and by then my shoes were soaked, so we plunged in and trudged through the water until we reached the first BDA. 

It looked like something humans had built. The willow reeds were too nicely woven into a thick mesh between tall, straight, deeply sunk wood pilings that anchored the dam. But, in places, the wild had won out: Bits of the dam were listing and, here and there, the water was pouring over the woven willow’s top. The creek, soon after the snowmelt, had swelled and pummeled the structure, plugging up parts with detritus, and opening up others. Though the dam was still there, the creek wasn’t fully stopped up, just slowed in places.

Wilson was delighted by this outcome. The structural failures were natural successes. The creek pooled behind the dam while also spilling over and around it: pouring, churning, stirring, reshaping, tilling—renewing the land itself. An environment shaped by beavers is often described as dynamic, and you could actually hear it in the water’s trickles, splooshes, and silence—a symphonic waterway. 

Farther down the creek was a strand of dead trees. I asked Wilson what was going on down there and she told me that’s where the real chaos was, because a family of beavers lived there. We walked down toward the dead trees and, as we neared, Wilson and I spotted a woman hunched over a section of creek bank, staring intently at the water. The creek here was indeed chaotic. The beavers had dug channels, as they do, to avoid awkward passage over land. The waterways cleaved the landscape into jigsaw-puzzle pieces. It was easier just to stick to the waterways, rather than chance it on land and trip into an unseen channel. 

Ryan Bradley
Ryan Bradley
Ryan Bradley is a writer and editor whose work also appears in the New York Times Magazine, Popular Science, the Guardian, Fast Company, Fortune, and GQ. He lives in Los Angeles.





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