On an early October morning in 2025, a group of BeaverCorps trainees lugged a 40-foot-long section of plastic pipe with a 7-foot-wide wire cage on one end into a stream in El Dorado Hills, near Sacramento. They had built this device, called a pond leveler, as part of their training to become beaver coexistence professionals. Beavers had moved into a subdivision, and the local community service district was concerned that their dam would cause flooding. But instead of sending someone out to euthanize the beavers, the CSD had decided to try a new approach: living with them.
After decades of viewing beavers as pests, California is finally beginning to welcome them home. And not a moment too soon. With perhaps the world’s most intensely modified hydrology, the state leads the country in acres burned by wildfires and number of homes at risk from them, and according to one study, it is second only to Nevada for drought risk. California’s vaunted biodiversity is also imperiled. But these legendarily industrious architects are primed to help us out.
“Beavers are tough neighbors—I think they might be more stubborn than people. When they want to build a dam, they are an unrelenting force,” says Emily Fairfax, an ecohydrologist who has dedicated herself to quantifying the benefits of beaver dams. “The beaver doesn’t pull permits or submit design plans, so it’s very hard for us to use our structured environmental-conservation workflows with an animal that is best described as ‘chaotic good.’ But I think we’re finally ready to stop jogging on this treadmill of being at war with beavers and figure out how to work with them. Because now we have a much larger common enemy: climate change.”
This article appears in Issue 35 of Alta Journal.
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Like humans, beavers have learned how to transform their environments to suit themselves. They build dams to create ponds that are deep enough to allow them to escape from predators. These ponds and surrounding wetlands are vital ecosystems that nurture numerous species, including endangered salmon, and can reduce water pollution. Now, important environmental efforts that have been siloed in the past are coming together around this ecosystem engineer. “Beaver conservation is important because it gets people talking who haven’t talked to each other before,” says Kate Lundquist, a director at Occidental Arts & Ecology Center, in Sonoma County, who works on policies for healthy watersheds and how beavers can contribute to them.
RODENT OR AQUATIC DYNAMO?
By the early 1900s, beavers in North America had been hunted for their fur almost to the point of extinction, and humans lost a self-supporting system of ecological richness that we’ve slowly come to recognize. Over millennia, beavers had engineered valleys filled with rich soil that became highly productive farmland for humans. In his 2018 book, Eager: The Surprising, Secret Life of Beavers and Why They Matter, environmental journalist Ben Goldfarb describes the loss of this ecosystem as causing an “aquatic Dust Bowl.”
Critical for California, beaver dams create spongy land that is resilient in the face of wildfires, resists erosion, and retains precious groundwater. Fairfax, an assistant professor at the University of Minnesota, was the first to measure the impact of beaver dams in wildfire-stricken areas, showing that sites with dams were three times less damaged than those without. “It’s similar to trying to start a fire with a pile of wet leaves versus with dry kindling,” she states in a 2020 paper titled “Smokey the Beaver” (deftly summarized in a viral stop-motion animation).
Beavers are exquisitely adapted to do this job: They split off from ancient rodents 54 million years ago, becoming specialists in burrowing and eventually adopting a semiaquatic lifestyle. Alas for the giant six-foot-long beaver, it didn’t have the ability to chew wood, and scientists think it may have gone extinct when it lost its diet of soft aquatic plants at the end of the most recent ice age. But the beaver species that did survive have a diverse diet that includes tree bark, and they stash branches in a mud “refrigerator” for sustenance during freezing winters. They have iron-reinforced teeth that let them power through wood, paws with opposable pinkies for lugging branches, webbed hind feet for fast swimming, and third, clear eyelids that let them see underwater.
Yet these multitalented creatures have been as rare as zebras in places that should be their natural territory. In the early 1800s, Russian and American fur traders began despoiling coastal California of sea otters, beavers, and other furry mammals, and overland trappers hunted most of the remaining beavers thereafter. Early biologists concluded incorrectly that beavers were not native to large swaths of California, which helps explain the state’s ambivalence toward the animals.
Beavers raise concerns, real and perceived, about flooding. In addition to damming natural waterways, they opportunistically dam human-made systems for flood control and irrigation. When they dam a culvert—a pipe that runs under a road to prevent flooding—the ensuing chaos is particularly costly. Beavers also don’t distinguish between trees in the wild and trees in landscaping. Traditionally, when beavers and landowners have come into conflict, the landowners have arranged for the beavers to be lethally trapped. The CSD in El Dorado Hills had removed beavers at least twice before. “They always come back,” says CSD president William Grava. “We can’t keep pouring money into getting rid of dams.”
Enter the pond leveler, one of various devices that have effectively reconciled beaver and human infrastructure. Inserted into a notch in the El Dorado Hills beaver dam, the pipe brought the water level down by nine inches, ensuring that any excess stormwater would drain through it while keeping the pond at a beaver-friendly depth of at least three feet. The BeaverCorps trainees also learned how to wrap wire fencing around trees to protect them from being chewed.
In the afternoon, the trainees practiced soft skills: how to talk to landowners. By constructing residences on what had been oak savanna, developers had unwittingly created prime beaver habitat. What had likely once been a tiny intermittent creek had become a year-round stream, fed by irrigated lawns and runoff from impermeable roofs and roads. It had islands of tangled branches and lush vegetation growing in and around it—a wonderfully messy oasis in the midst of an orderly suburb. About 200 yards downstream from where the pond leveler had been installed, the beavers had built another dam (one beaver family can build a whole network of dams). The BeaverCorps instructor pretended to be a worried landowner and pointed at a culvert, which was partially filled with water. One of the trainees, a civil engineer, noted that having water in the drainage pipe was actually helping protect the bank from erosion during floods. (Throughout the West, the absence of beavers and overgrazing by cattle have caused streams to erode and become deep gullies: the opposite of wetlands.) Another pond leveler was in order.
Trainee Cathy Mueller, a biologist, installed the additional pond leveler a few days afterward. Mueller and 13 other trainees are the first BeaverCorps cohort in California and are key to the state’s new focus on beaver coexistence. Since 2023, when landowners have applied for depredation permits to remove beavers causing problems, the California Department of Fish and Wildlife has encouraged coexistence measures whenever feasible. And it connects landowners with consultants like Mueller who can be found via the California Beaver Help Desk, a new website developed by the Occidental Arts & Ecology Center.
As the stewardship manager at American River Conservancy, Mueller already had a firm appreciation of what beavers do. The nonprofit ARC protects open space in the American River and Cosumnes River watersheds, and one of its projects is to restore nearly 100 acres of degraded ranchland to native meadows.
In 2024, Mueller used a $333,000 Fish and Wildlife grant to install 125 beaver dam analogues—human-made beaver dams—to nudge the restoration forward. “People are walking in, using hand tools, and behaving as beavers,” she explains. “The material is taken on-site, so it’s mostly lodgepole pines but also some firs and willows. It’s like a lasagna of fine branches and heavier branches all woven together, some giant logs that hold the whole thing down, and then posts are driven through to further hold it in place. They create the starting frame for beavers to add on to.”
In June 2025, a year after the beaver dam analogues were installed, Mueller was walking through a meadow and suddenly found herself waist-deep in water. “The surface looked solid, but there was a pocket of water underneath that wasn’t there before. So that is evidence that the meadow is wetter than it was a year ago. I had to crawl out on my elbows,” she says, laughing.
WELCOME BACK TO CALIFORNIA
To continue the good work, Mueller hopes to import actual beavers. She’s applied to the state’s beaver restoration program, which also launched in 2023. Fish and Wildlife touted that it was the first time the state had reintroduced beavers in nearly 75 years—a reminder that California had tried this once before, transplanting beavers from other states “not only for the purpose of producing a valuable fur crop, but with the hope that full advantage may be taken of the water storage, erosion control, and aesthetic values that may be derived from…properly located beaver colonies,” according to a 1946 report by Arthur L. Hensley. The previous program had helped increase the range and numbers of beavers (some were dropped by parachute into the Sierra Nevada), but was also marked by conflicts; effective coexistence devices had not yet been developed.
This time around, Fish and Wildlife is relocating a limited number of “problem” beavers and prioritizing tribal lands to reestablish historic cultural connections to the furry creatures. The department also aims to release a statewide beaver restoration plan later this year, which will identify priority watersheds that could benefit from beavers (and from interventions like beaver dam analogues). Advocate Heidi Perryman, who led the movement to keep beavers in place after they showed up in downtown Martinez, in the Bay Area, in 2007, would like to see the state go one step further. “My fantasy is that California would institute environmental tax credits—you’re benefiting California so much by having beaver habitat on your land that you actually get a benefit on your taxes,” she says. “You’re changing fire risks and increasing biodiversity. These are the big things we should be thinking about.”
Like Hensley back in 1946, Mueller has been promoting the benefits of living with beavers. After the two pond levelers were installed in the El Dorado Hills subdivision, somebody breached a third dam. The beavers fixed the damage overnight and built the dam back taller and wider; a third pond leveler is under consideration.
“I tend to steer people towards the benefits and how lucky they are to have all the wildlife in their neighborhood,” Mueller says. “They don’t know that they have river otters and everything else that is there because of these beavers. There’s a kingfisher [a fish-eating bird with distinctive plumage] in that neighborhood, which I’ve only seen in wild places before. I have found kids a couple of times playing in the beaver ponds, which is really cool. They’re not looking at their screens. They’re out enjoying these ponds.”•
Lydia Lee writes frequently about design and architecture in the San Francisco Bay Area and is a local bicycle advocate.
