California Released 28 Beavers Into Mountain Streams — One Year Later, the Water Surface Grew 23%

[00:00:00]In the spring of 2025, a field biologist working for the California Department of Fish and Wildlife walked along a creek bed in Plumis County that she had last surveyed 18 months earlier. The last time she had been here, the creek ran shallow and narrow through a scarred valley, still recovering from the Dixie Fire. Charred stumps lined the banks.

[00:00:20]The water moved fast and thin, barely wetting the gravel beneath it. Ash still dusted the stones where wild flowers should have been growing. Now she was standing at the edge of a pond that had not existed before. Behind a dam stretching more than 328 ft across a channel that had once been barely a trickle, the water spread out in every direction. Willows had taken root along the margins, their branches dragging the surface. A sandill crane lifted off from the far edge of what was now a functioning wetland. The biologist checked her satellite imagery against the readings on the ground. Surface water at this site had increased by approximately 23%, not over a decade, not with millions of dollars in engineered infrastructure in roughly one year. And the engineers responsible for all of it weighed about 40 lb each. This is the story of how California released 28 beavers into mountain streams for the first time in nearly 75 years, and how those animals began rebuilding a landscape that humans had spent two centuries destroying. To understand why this matters, you need to know what was lost. Before European settlers arrived in what is now California, the North American beaver occupied the vast majority of the state's watersheds.

[00:01:32]Scientists estimate that between 60 million and 400 million beavers once lived across North America. Their dams and ponds covered more than 300,000 square miles of the continent. That is an area roughly the size of Texas. A tenth of the total land area was rich, ecologically diverse wetland, a vast mosaic of habitat for insects, amphibians, fish, birds, and mammals that stretched from the Arctic to Mexico. These were not just patches of standing water. They were biological engines. Beaver dams slowed the movement of water through valleys, forcing streams to spread across flood planes instead of cutting deep, narrow channels. The ponds behind the dams stored water during wet periods and slowly released it during dry spells, [music] creating what hydraologists now call drought buffers. These buffers kept streams flowing when they would otherwise have run dry. Sediment settled behind the dams, filtering water naturally and creating layers of rich organic soil that built up over decades and centuries. The still water raised the water table, which in turn fed meadow grasses, willows, and aspens that held the banks together and cooled the streams enough for trout and salmon to thrive. The dams created pools of deeper, slower water where juvenile fish could shelter from predators and grow.

[00:02:50]Fallen branches incorporated into the structures offered refuge from strong currents. Every beaver dam was simultaneously a small-scale water treatment plant, fire break, fish hatchery, and carbon sink. All running on willow bark and instinct. No electricity required, no maintenance contracts, no environmental impact reports. Then the fur trade arrived.

[00:03:11][music] Beginning in the early 1800s, trappers swept through California's rivers and mountains with devastating efficiency. The California fur rush preceded the gold rush by decades and was arguably more transformative to the landscape. Before 1825, seagoing trappers had already been harvesting beaver along the northern and central California coast. Mountain man Jedodiah Smith arrived overland from the east in 1826, opening new trapping routes.

[00:03:39]Within a few decades, the beaver population across the state was decimated. The damage was not limited to California. Across North America, the fur trade killed tens to hundreds of millions of beavers over the course of roughly two centuries. The industry drove westward expansion more than any other single factor. By 1912, fewer than 1,000 beavers were estimated to remain in all of California. The ecological consequences cascaded immediately and relentlessly. Without beaver dams, streams began to cut downward, a process called channel incision. Water that had once spread across broad flood plains now rushed through narrow trenches.

[00:04:18]Wetlands drained. The water table dropped. Meadows that had been saturated for centuries dried out and were colonized by upland plants and encroaching conifers. Fire which had once been slowed and stopped by moist beavermaintained wetlands now ripped through dry valleys with nothing to check it. Rivers that had once meandered through complex braided channels became more like canals or sewers. Water pollution worsened. Erosion accelerated.

[00:04:44]The land itself began to forget what it had been. Making things worse, a scientific mistake hardened into policy.

[00:04:52]20th century zoologologist Joseph Grenell published an influential assessment in 1937 that defined the beaver's native range in California as a narrow strip limited to the central valley and parts of the Clamoth and Colorado River basins. His conclusion excluded the Sierra Nevada entirely. For decades after, wildlife managers cited Grenell as justification for treating any beaver found outside that narrow lowland range as a non-native pest. The policy was straightforward. Kill them, remove them, they do not belong here.

[00:05:26]From roughly 1920 to 1950, the state had actually run a program to relocate problem beavers to mountain areas, and the population rebounded from 1300 in 1942 to 20,000 by 1950. But after World War II, the push for development largely won out. Brock Dolman, co-founder of the accidental arts and ecology center and co-director of its water institute in Soma County, described the prevailing attitude bluntly. The approach was to get them out of our way because they were an impediment to progress. If they were not native, all the better, because then there was no reason not to kill them. By the early 2000s, California had what Dolman's colleague Kate Lungquist called a massive beaver blind spot.

[00:06:10]Other western states like Oregon, Washington, and Utah were already investing in beaver restoration and seeing results. California was still issuing depradation permits to kill an estimated 1,000 to 3,000 beavers per year. Here is the key insight that changed everything. It did not come from a government agency or a university laboratory. It came from a rock wall on the Tuli River Indian Reservation in the southern Sierra Nevada foothills.

[00:06:35]Kenneth McDarant, a member of the Tuli River tribe and a former tribal councilman, had passed by an ochre red pictograph at a site called Painted Rock his entire life. Four paws, a distinctive paddletail, unmistakably a beaver. The painting was estimated to be between 500 and 1,000 years old. One of many images of people, geometric designs, and wildlife created by the Yokutz people on the walls of a rock shelter beside the South Fork of the Tuli River. McDarant had seen it countless times, but it took a crisis to make him really look at it. Around 2014, a succession of drought years parched the reservation's 55,000 acres, streams thinned to trickles, the [music] land baked. Tribal leaders were searching for ways to conserve water and shore up their watersheds. McDarant looked at that pictograph and saw something he had never considered before. If beavers had lived on these lands for centuries, if they had been significant enough for the Yokuts people to paint them on sacred walls, then maybe bringing them back was the answer. In Mcdarin's own words, the answer was in our pictographs. Sometimes you need to just look at things more often. The Tuli River tribe began advocating for beaver restoration in earnest. They were told flatly by state officials that there was no legal way to move beavers in California. They kept pushing. McDarant later said that all the tribes had words for beaver from San Diego to Mount Shasta, which was an indication that these animals existed across those territories. The pictograph was not just art. It was a thousand-year-old water management plan.

[00:08:10]Meanwhile, nearly 400 m to the north, a parallel story was unfolding. The Maidu Summit Consortium representing nine member organizations of mountain Maidu Indians in Lassen and Plumis counties had been fighting since 2003 to reclaim their ancestral homeland. A valley in the mountains of Plumis County that settlers had named Hanbug Valley was known to the mountain Maidu as Tasmam Coyom, meaning tall [music] grass. It sits in the upper Feather River watershed at an elevation of roughly 5,371 ft above sea level. It had been a major Maidu population center for generations before Euroamerican settlers appropriated it during the gold rush and established the now abandoned town of Longville. [music] For over a century, the land passed through the hands of various power companies, eventually ending up with Pacific Gas and Electric.

[00:09:00]On September 20th, 2019, as part of a California Public Utilities Commission settlement agreement with the utility, 2325 acres of Tasmam Coyom were transferred back to the Maidu Summit Consortium. It was the first time that ancestral lands in California had been returned to a tribe not recognized by the federal government. Ben Cunningham, chairman of the consortium, said simply that it was good to have them back where they belong, but the land they reclaimed was wounded. The meadow ecosystem had been degraded by decades of logging, grazing, and water diversion. Streams ran insized and narrow through channels that should have been broad wetlands.

[00:09:38]And then in July of 2021, the Dixie Fire came, sparked by Pacific Gas and Electric Equipment. It became the largest single fire in California's recorded history, burning nearly a million acres and destroying over,200 structures. The fire tore through Tasmam Coyom, burning down a historic stage coach stop, destroying fencing used for cattle grazing and ravaging culturally significant planting areas. A tribal leader described the damage in terms of generations. It will be generations before we even get back to what we lost.

[00:10:10]He said, "I will not see that in my lifetime." The meadow that the mountain had waited over a century to reclaim was charred and scarred within 2 years of their getting it back. After the fire, restoration work accelerated. The accidental arts and ecology center was invited by the consortium to develop a beaver recruitment strategy for the valley, which was completed by June of 2020. As a first step, teams installed beaver dam analoges, low tech structures made from logs and branches designed to mimic the hydraological effects of real beaver dams and attract actual beavers back to the area. In 2022 and 2023, the California process-based restoration network hosted build like a beaver workshops at Tasmam Coyom, where participants installed 50 structures using materials from encroaching conifers and increased the stream length by 75%. Meanwhile, the science was settling the historical debate. [music] Researchers from the Water Institute found a remnant beaver dam in nearby Red Clover Valley that was carbon dated to 1270 years ago, proving that beavers had occupied these high elevation Sierra Nevada streams for over a millennium.

[00:11:22]Grenell's narrow range assessment was simply wrong. In 2022, Governor Gavin Nuome signed Assembly Bill 1757, creating the state's initiative to expand nature-based solutions. The California Department of Fish and Wildlife established the Beaver Restoration Program with dedicated funding of $1.67 million in fiscal year 2022 to 2023 and $1.44 million annually thereafter. The state hired five dedicated scientists. For the first time in decades, California was officially treating beavers not as pests but as partners. The logistics of the first transllocation were precise and deliberate. The team identified problem beavers in lowland areas, primarily in the Sacramento and Sanwaqin River wersheds where their dam building was causing flooding and conflicting with agriculture and municipal infrastructure. Rather than killing these animals, the new approach was to trap them safely and transport them to sites where their engineering instincts could serve restoration goals. On October 18th, 2023, the first beaver conservation transllocation in nearly 75 years took place. A family of seven beavers, a breeding pair, and five offspring were released into Yellow Creek in Tasmam Coyom. They joined a single resident beaver already living in the valley. CDFW director Charlton Bonham was there for the release. He said that we can make our future different from our past. Our past is one where we treated these animals and others as varmints, as nuisances, and our culture over time ran them off the landscape. Shannon Salem Williams, a Mountain Maidu woman and program manager for the consortium, watched the beavers slip into the water that day. She described it as a full circle moment.

[00:13:09]The Mountain Maidu consider Beaver, which they call Hihm, to be family.

[00:13:15]William said it was like a big welcoming home. A CDFW staff member who was present recalled the moment one of the smallest kits rode on the back of a sibling's tail, surfing into the creek.

[00:13:26]He said he did not think it set in for days afterward, but that moment would go down as one of the highlights of his entire career. Over the following year, the program expanded. Five more beavers went to a second site on Maidu Summit Consortium land. [music] 16 beavers were transllocated to three sites on the Tuli River Reservation in Tari County. By September of 2024, 28 beavers had been placed across five release sites in the Sierra Nevada. Each animal was fitted with a tracking tag. Trail cameras captured nighttime activity. Satellite imagery tracked changes in surface water. Biologists measured water temperature, sediment load, vegetation coverage, and species presence. They measured everything they could, and then they waited. Scientists expected modest results at best. Transllocation survival rates for beavers are historically uncertain. The sites had been degraded.

[00:14:19]Tasm Coyom had been scorched by the Dixie fire just 2 years earlier. The Tulle River sites had known predation risks, including black bears and wolves from the Yolomni Pac that had first appeared near the reservation in 2023.

[00:14:32]The models were not encouraging. Nobody was predicting dramatic landscape transformation within 12 months. What they found defied every projection. At Tasm Coyom, the beavers did not just survive. They engineered on a scale that stunned the monitoring teams. The colony constructed a primary dam stretching 100 m over 328 ft across a creek channel at the edge of their pond. They dug a network of canals radiating outward from the pond into the surrounding flood plane, pushing water across terrain that had been dry since the fire. They blocked off a nearby rivullet, redirecting its flow to expand their wetland complex. They burrowed into the banks of a creek further downstream.

[00:15:14]According to the CDFW's April 25 status report, the surface area of water at Tasm Coyom had increased by more than 22%. At another site, the figure reached 23%. Let me put that in context. This was a valley that had been drained, grazed, logged, and degraded for a century and then hit by the largest single wildfire in California history.

[00:15:38]Within roughly one year of beaver activity, more than a fifth of the lost surface water had been reclaimed by 28 animals working with sticks, mud, and instinct. The beavers had produced two litters of kits, meaning the population was not just holding, it was growing.

[00:15:55]The cascade effect was already visible and accelerating. As water spread behind the dams and through the canals, willows began colonizing the banks. Wetland grasses returned to areas that had been dry since the fire. Biologists documented willow fly catchers arriving in the restored habitat. That matters enormously. The willow fly catcher is listed as endangered in California.

[00:16:17]Sandill cranes appeared in the shallows.

[00:16:19]River otterters were spotted in the expanding waterways. The silt trapped behind beaver dams was filtering water, improving quality downstream. The deeper pools created by the dams held cooler water temperatures, [music] which is critical for fish survival during California's increasingly brutal summers. Each outcome triggered the next. Beavers store water. [music] Stored water raises the water table. A higher water table grows vegetation.

[00:16:44]More vegetation cools the stream. Cooler streams support fish. More fish attract predators and scavengers who distribute nutrients through the surrounding forest. The system was rebuilding itself. Not the way engineers rebuild things, the way nature rebuilds things.

[00:17:00]Slowly, then suddenly, Emily Fairfax, an ecohydraologist and assistant professor of geography at the University of Minnesota, put the results in scientific context when she spoke to Mongabay. She said that beavers are really powerful ecosystem engineers, [music] and the number of services they provide and the ways they build resilient landscapes is honestly too much to just rattle off all at once. Fairfax's own landmark 2020 study published in the journal Ecological Applications had already demonstrated that beaver damned riparian corridors stay green during wildfires across the western United States. Her research showed that the decrease in vegetation greenness during fire in areas without beaver was 3.05 times as large as in beaver damned areas. The implication for California, a state that loses billions of dollars to wildfires annually, is extraordinary. Beaver wetlands do not just store water, they fireproof the landscape. And here is a detail that rarely makes it into the conversation. Man-made mitigation wetlands cost from 10,000 to $100,000 per acre to build. Each beaver family creates and maintains several acres of wetlands for free. The beavers work around the clock every day of the year without salaries, without equipment budgets, without engineering contracts or environmental review processes. They maintain their own infrastructure instinctively and rebuild it when storms or floods damage it. A 2025 study led by Jesse Morave and published in Ecological Applications modeled potential beaver dam building capacity across the Sierra Nevada and found that beaver dams have the potential to store a total of 120 million cub m of surface water and create 2200 km of fire resilience in high fire risk areas. The study estimated that the Sierra Nevada can currently support about 440,000 beaver dams, but that only 51% of historical dam building capacity remains compared to pre-EU European settlement levels.

[00:19:02]That means the region has lost half its natural water and fire infrastructure.

[00:19:07]This is not romantic nature worship.

[00:19:09]This is hard-nosed math. The infrastructure is free, the engineers reproduce, and the potential for scale is enormous. Now, here is the part of the story that most coverage leaves out, and it is the part that matters most if this model is going to work beyond two pilot sites. Not every release went well. On the Tulle River reservation, the results were sobering. All seven beavers from the first release may have been killed by predators. The CDFW's April 2025 report noted that overall survival across all sites was estimated at 40 to 60% with the primary causes of mortality being predation, illnesses including pneumonia, and capture related stress. At one Tuli River site, monitoring equipment was tampered with by humans. An adult male beaver's tracking tag was recovered nearly 200 m from the stream channel, almost certainly indicating predation. For the beavers that did not make it, this was not a success story. It was a grim reminder that transllocation is a blunt instrument applied to a complex problem.

[00:20:10]Heidi Perryman, founder of the nonprofit Worth a Dam, raised pointed concerns about the Tuli River releases specifically. She argued in a letter to CDFW that more should have been done to prepare release sites, such as ensuring that the entrances to temporary lodges were fully submerged underwater to give beavers time to escape predators and adapt to unfamiliar territory. She estimated through public records requests that California still allows the killing of 1,000 to 3,000 beavers per year through depradation permits issued to land owners whose property suffers beaver damage. In her view, it remains remarkable how many times California turns down the opportunity to coexist with beavers. Even Brock Dolman, one of the most prominent advocates for beaver restoration in the state, tempered expectations. He cautioned against turning beavers into a silver bullet, saying that restoration must always return to the whole systems approach. And then there is the funding.

[00:21:07]In 2024, budget cuts hit the CDFW's newly hired human wildlife conflict staff, the very people tasked with helping farmers and ranchers coexist with beavers that the state was simultaneously asking them to tolerate.

[00:21:21]The tension is real and unresolved. A rancher in the Sacramento Valley whose irrigation canal gets damned by a beaver is not thinking about fire resilience in the Sierra Nevada. A walnut farmer whose orchard trees get chewed through is not interested in ecological cascade effects. Historical research confirms that this tension is not new. In the midentth century, ranchers in California's uplands generally viewed beavers favorably for their water table benefits. While lowland farmers complained bitterly about crop damage and flooding, the same animal was simultaneously a blessing and a curse depending on where it lived and whose livelihood it affected. For beaver restoration to work at scale, these people need practical help, not lectures about ecosystem services. The state created a $2 million program through the Beaver Help Desk, led by the accidental arts and ecology center to provide land owners with coexistence tools like pond levelers and tree wrapping. But the gap between aspiration and implementation remains wide, and the people who bear the costs deserve to be heard. Now return to Tasm Coyom. Walk the edge of that 328 ft dam in the early morning.

[00:22:31]The water behind it is still. The willows along the banks are green and thickening. A sandill crane stands motionless in the shallows. Somewhere beneath the surface, a beaver is reinforcing a lodge that did not exist 2 years ago. This valley was sacred to the mountain Maidu. For thousands of years, it was taken from them by settlers during the gold rush. It was owned by utility companies for over a century. It was burned by a fire sparked by the same utility's faulty equipment and it was returned to the tribe in 2019. Now through the quiet persistent work of animals that weigh less than a Labrador retriever, the meadow is coming back.

[00:23:08]The mountain word for beaver is hihm.

[00:23:12]They consider the animal family. When Shannon Salem Williams watched those first seven beavers slip into Yellow Creek in October of 2023, she was watching a homecoming. Not just the beavers coming home to the meadow, the meadow coming home to itself. What this project reveals runs deeper than hydrarology or wildlife management. It reveals what happens when humans stop trying to replace natural systems and start letting them work. 28 beavers relocated at a cost that would not cover the engineering feasibility study for a single conventional water project transformed a burnedout valley into a functioning wetland complex in roughly 12 months. They stored water. They filtered sediment. They raised the water table. They created habitat for endangered species. They built fire brakes that no bulldozer could match.

[00:24:00]And they will keep doing it generation after generation as long as we let them.

[00:24:05]The data refused to fit the models. The models said, "Modest outcomes." The models did not account for a 328 ft dam built by animals who have been perfecting this craft for 20 million years. This is happening across the Sierra Nevada and most people have never heard of it. It deserves to be one of the biggest stories in American conservation right now. So, I want to ask you, what part of this surprised you the most? Was it the 23% increase in surface water in a single year? Was it the fact that California spent 75 years refusing to do what a handful of 40 lb rodents could accomplish for free? Or was it the fact that the answer was painted on a rock wall a thousand years ago and nobody looked at it closely enough until the wells started going dry? Drop your answer in the comments. I read every single one. If you are not subscribed yet, now is the time. We cover stories about restoration and the people who are fixing what is broken.

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