How Beavers Are Bringing Oregon' s Dead Desert Back to Life

This is Bridge Creek, in the high desert of North Central Oregon. And right now, it's a ditch. A narrow trench cut into the dirt, water racing through the bottom and vanishing, dry cracked ground on both sides. But 200 years ago, this exact spot was a wetland. Willows, beavers, fish, the whole thing. So, what happened? A foreign fur company wiped out every beaver here on purpose, just to keep American trappers off the land. And once the beavers were gone, the whole place dried up and broke down into the ditch you are looking at right now. Then a team of scientists showed up and did something strange. They drove fence posts into the creek and wove sticks between them. Fake beaver dams. And they waited. And the real beavers came back. Took over the fake dams and went to work. Three years later, the dead ditch was green again. So, how does a row of fence posts bring a whole desert back to life? To understand how they fixed Bridge Creek, you first have to understand how somebody broke it on purpose. So, let's rewind to the early 1800s. Back then, this whole region was called Oregon Country. And two countries both wanted it. Britain and the United States. In 1818, they signed a treaty to just share it for a while. Now, the British fur trade out here was run by the Hudson's Bay Company. And in 1824, their governor, a man named George Simpson, landed on an idea. A nasty one. He figured, look, if American trappers find out how much beaver is sitting in these streams, they'll flood in and Britain loses the whole territory. So, why not make the place worthless? Trap out every last beaver, strip the country bare, and the Americans take one look and turn back at the border. He called it a fur desert. And he put it in writing. The country, Simpson said, is a rich preserve of beaver which for political reasons we should endeavor to destroy as fast as possible. So, who actually carried it out? A man named Peter Skeen Ogden. From 1824 to 1830, he led brigade after brigade out of Fort Vancouver, working these streams over and over until there was nothing left to catch. He pulled the beaver out faster than they could ever breed back. And it worked. By 1830, the beaver here were basically gone. Then, the cattle showed up. All through the 1800s and into the 1900s, ranchers ran livestock across this high desert. And the cows ate the willows and the young cotton woods right down to the nub. Which, bad news, are the exact plants a beaver eats and builds its dams out of. So now the creeks lost both halves of the puzzle at once. The animal that builds the dams and the wood it builds them with. See, a beaver dam slows water down. That's its job. So, take the dams away and nothing's slowing the water down anymore. Every winter storm, every spring snow melt comes ripping down the creek at full speed. And fast water digs, so year after year the creek cuts itself deeper into the ground. A little deeper with every flood until the water's running way down at the bottom of a narrow trench, far below the land on either side. Back when the creek sat up near ground level, it could spill over its banks and soak the dirt on both sides. That's what kept the whole place wet and green. But a creek stuck down at the bottom of a trench can't reach its banks anymore. The water just races through the bottom and leaves. So, ground on both sides dries out. The willows die. And in summer, the little bit of water that's left just sits in the open and cooks. And in that hot shrinking trench is the only home left for the mid-Columbia steelhead. It's a trout that's born up in these creeks, swims all the way out to the And Bridge Creek is one of the streams it has to spawn in. So now you've got a protected fish trying to hang on in a creek that's falling apart. So why didn't people just go fix the creek themselves? Well, they tried. You can bring in machines, reshape the banks, drop in big man-made structures. But it's slow, it's crazy expensive, and half the time the creek just breaks all over again. Fixing a whole watershed by hand is a losing battle. So the researchers asked a smarter question. What if, instead of fixing the creek themselves, they got the animal that built the place in the first place to come back and do it? The beaver. There was just one problem. The beavers had already tried. A few of them moved back into Bridge Creek on their own, but the only thing left to build was skinny little willow shoots. So their dams were flimsy. The first big flood would come through and rip them right out, usually within a year or two. The beavers couldn't get a foothold. So that's the puzzle the team was staring at in 2007. The creek needs beavers, but the beavers need a creek that isn't constantly trying to wash them away. So how do you break that loop? How do you give a beaver a dam strong enough to survive its first flood? But first, who are these people trying to fix Bridge Creek? Mostly ecologists and fishery scientists. Nick Bowis from Ecological Research and Utah State. Michael Pollack over at NOAA's fisheries lab up in Seattle. Joe Wheaton, also Utah State. Nicholas Weber from Ecological. Plus folks from NOAA and the Oregon Department of Fish and Wildlife. In the same year, 2007, Bridge Creek got tagged as an intensively monitored watershed, which basically means they wired the entire stream up to count every fish and measure every inch of habitat for years on end. So Pollack's sitting there with this problem. The beaver can't keep a dam up on its own. So give it a head start. Build a wall that's tough enough to survive a flood and let the beaver come pile mud and sticks on top and finish the thing into a real dam. They called it a beaver dam analog, or BDA for short. And honestly, the build is almost stupidly simple. You grab untreated wooden fence posts and pound them straight down into the stream bed in a line across the channel, about a foot apart. Then you weave fresh willow branches between the posts in and out, in and out, until you've got this leaky little wall of sticks. Then you pack mud and rocks against the upstream side to plug it up. Set the posts about as tall as a beaver dam would sit and that's it. A small crew can knock one out by hand in a single day and using stuff that's basically lying around the creek. Now some of the groundwork was already done. Back in 1988, the BLM had cut grazing along these banks and a few years later, Oregon shut the watershed to beaver trapping. So the willows had started creeping back, but pulling out the cows and the trappers still wasn't enough. The creek was cut way too deep down in its trench for a few willows to drag it back out. So in 2009, the crews waded into the lower 32 kilometers of Bridge Creek and started pounding posts. Over 120 BDAs. And they deliberately left big stretches totally untouched, so later they'd have something honest to compare against. And every single BDA was built to pull off four jobs at once. Slow the water so floods spread out over the floodplain instead of digging the trench even deeper. Trap sediment so the stream bed climbs back up. Hand the local beavers a wall so that they can actually build on and dig out deep slow pools for the young steelhead to live in. But nobody had ever tried this on an entire watershed before. Ever. So now there's a hundred plus fake dams sitting in a dead creek and really only one question left. Would the beavers even show up? Oh, they showed up. Within weeks. The crew would pound in a line of posts and within days there's a beaver out there at night, dragging out willow into the structure, jamming mud onto the gaps. Nicholas Weber, the guy running the project day to day, put it about as plainly as you can. Wherever we put structures, beavers came and set up shop. And once they had a wall that actually held, game on. By 2013, the beavers had grabbed nearly 60 of the BDAs and stuffed them so full of mud and sticks, they turned into real working beaver dams. And then they went and built 115 brand new dams of their own up and down the whole creek. Beaver actually jumped to about eight times what it used to be. And the creek just took off. The dams caught so much sediment that some of the original BDAs literally got buried in mud and vanished. All that trap dirt piled up and lifted the stream bed. So the creek starts climbing up out of its trench year by year, until finally the high water can spill out over the old floodplain again, instead of just blasting through the bottom of the ditch. The wet old area of the creek tripled. Side channels, those little branching threads of water coming off the main one, grew by more than 1,200 percent. Wet ground came back. Willows and cottonwood started popping up along the banks that used to be bone dry dirt. And behind every dam, the water pooled up deep and slow. Habitat changes they figured would take a decade, happened in one to three years. So the habitat came roaring back. Great. But that was never really the whole point. The point was that one fish, the threatened steelhead, still hanging on downstream in that trench. So the real question was simple. Did all this new habitat actually put more fish in the water? It actually did. The fish basically exploded. In the stretches with the BDAs, the number of young steelhead the creek cranked out jumped to about 175 percent over the untouched control stretches. Their survival, meaning the odds of a young fish actually makes it to the next stage of life, went up 52 percent. Put those together, and Bridge Creek was pumping out nearly three times the steelhead of the control. And the fish numbers really took off about four years after those first posts went to the ground. So Bowis and the team wrote the whole thing up and published it on July 4th, 2016 in the journal Scientific Reports. And it was a first. Nobody had ever run an experiment at the scale of a whole watershed and proven that the beavers and their dams could rebuild the population of a fish protected under the Endangered Species Act. They had the counts, reach by reach. And it wasn't just the steelhead cashing in. These new wetlands are exactly the wet meadows spreading off the creek feed greater sage grouse, a bird that's been quietly disappearing all over the west. So you slow the water down in one creek, and a whole list of other species come back riding along with it. Then there's the part that makes the accountants happy, the price. One BDA runs you a few hundred bucks, fence post, willow, and a crew with hand tools. Now compare that to regular river restoration, the kind with excavators regarding the banks and engineered structures craned in by machine. That'll run you hundreds of thousands, even millions of dollars for a single mile of stream. Bridge Creek got fixed for a tiny sliver of that. And then once the beavers took the wheel, they did all the upkeep for free. Every night. Patching dams, building new ones, forever. So of course, the idea spread. The Forest Service, the BLM, Oregon Fish and Wildlife, they all started using BDAs to fix beat up streams on public land across eastern Oregon. Soil and Water Conservation Districts and Watershed Council started walking private ranchers through the permits so they could go pound post into their own creeks. And get this, ranchers who'd spent a hundred years trapping beavers as strata pests were suddenly out there building fake beaver dams just to hold water on their land through the dry season. Right now there are crews pounding posts and weaving willow in Utah, Nevada, Idaho, Wyoming, Montana, and Northern California. All of it tracing back to that one creek in Oregon. And the reason it all works is almost dumb in how simple it is. The pieces were already there. The beavers were already in the landscape, just stuck. The willow seed was already sitting in the dirt. The steelhead was already swimming upriver every single year, looking for somewhere, anywhere, to spawn. And the animals walked through and did the rest themselves. So that's what a couple hundred bucks of fence posts can do to a dead creek. But the real proof is just what Bridge Creek looks like today. Today, you can barely find the trench. All around the dry, cracked pasture still rolls off into the distance, and it's labbed with birds. Beaver dams sit where the bare fence posts used to stand, packed thick now with mud and sticks. And in the cool pools behind them, young steelhead, the same threatened fish that were baking in a hot ditch 15 years ago. And at night, a beaver slips into the water, drags a fresh-cut willow branch across, and works it up into the top of the dam. That's it for this one. Drop a like, and I'll catch you in the next one.