Creek Restoration with Beavers


What we do to encourage beavers on Elder Creek:
• Never kill beavers and encourage others to join us in protecting them.
• Regularly comment to California Fish and Wildlife to prioritize restoration of beaver populations.
• Build small, beaver-like check dams and baffles in the creek in mid- to late spring (depending on flow).
• Leave cottonwood and willow along the creek, occasionally removing dead wood and coppicing some of the willow.

Why Beavers?
The pre-European contact population of beavers in North America was at least 60 million, and likely much more than that, some estimates reaching 400 million. This translates to 10 to 50 beavers per mile of stream! Before the 1400s, beavers inhabited almost all of what we now call Canada and the United States, plus a sliver of northern Mexico. Except for the driest western deserts and the alligator-rich swamps of Florida, they ranged from coast to coast and from just south of the Rio Grande to the Arctic treeline, as well as north along the Mackenzie and Coppermine rivers to the Arctic Ocean.

In the words of explorer and cartographer David Thompson, who crossed North America in 1784, the entire northern half of the continent was originally “in the possession of two distinct races of Beings, Man and the Beaver.” Thompson’s authority to make such statements came from surveying and mapping one-sixth of North America and talking with countless indigenous elders who had known of the beaver’s glory days.

Cherie Westbrook, an associate professor in the University of Saskatchewan’s department of geography and planning, corroborates Thompson’s anecdotal evidence and brings an ecohydrologist’s perspective to the discussion. According to Westbrook, 85 percent of all watercourses in the United States — and a comparable, though unquantified, percentage in Canada — are headwater streams and, therefore, small enough to be dammed by beavers. This continent-wide network of fine blue lines represents a wealth of potential beaver habitat. “We’re talking about beaver in nearly every headwater stream across North America prior to European colonization,” says Westbrook. (from Canadian Geographic)

This historical information gives us the ability to surmise the critical role of beavers in making this continent so incredibly fecund, as it was prior to European colonization. The ways they benefit the watersheds in which they live are numerous and well-documented. Here are just a few:

  • Reduced stream sedimentation and erosion
  • Stream temperature moderation
  • Higher dissolved oxygen levels
  • Overall improved water quality
  • Increased natural water storage capabilities within watersheds, including recharge of ground water aquifers
  • Reduced stream velocities, which means a decreased number of extreme floods
  • Removal of many pollutants from surface and ground water
  • Drought protection through increased year-round stream flow
  • Improved food/habitat for fish and other animals, including 43% (according to one source) of the endangered species that the US Department of Fish and Wildlife is mandated to protect

All of these improved hydrological effects locally, applied across an entire continent, add up to a significant factor in curbing the droughts and weather extremes of climate change:

In 2002, when University of Alberta biologist Glynnis Hood was in the middle of getting her PhD, the Prairies experienced the worst drought on record. She watched the wetland dry up “right before her eyes.” But where beaver dams existed, the pond water remained. Poring through 54 years of historic aerial photos, records of beaver populations and climate data, she discovered that the ponds with active beaver lodges had nine times more water during droughts than ponds without dams. In dry summers, the beavers kept water from trickling out and built channels to guide the water in; they had more impact than any rainfall or drought. Dr. Hood says this wasn’t a surprise to some of the older farmers, who often kept well-placed beavers on their land. Yet she would go to conferences where engineers would give presentations on river flow (with beaver dams in their photos) and never mention the animal. In wetland and river restoration, which in the U.S. has cost billions of dollars, the very creature responsible for shaping the landscape was largely absent from the discussion. (from the Globe and Mail)

Beaver: Back to the Future from Grand Canyon Trust on Vimeo.

Thanks to a high density of plant matter and a low rate of decomposition, wetlands may be the world’s best ecosystems for capturing and storing the carbon from CO2. Their destruction, on the other hand, releases lots of CO2 into the atmosphere as their soils dry out and oxidize. So the removal of beavers and their wetlands from most of North America has increased atmospheric CO2, while bringing them back would do just the opposite. At no charge!

Beavers on Elder Creek
At the most recent State of the Beaver Conference in Oregon (January, 2013), Michael Pollack, from NOAA Fisheries, showed a power point presentation that included a simple graphic (see below) depicting the cycle of stream/river beds through hundreds, even thousands, of years. Mr. Pollack’s accompanying descriptions of the point in the cycle that is farthest from most healthy–called incision–match what is observable on many stretches of Elder Creek. He stated that this type of degradation happens throughout the world, and that where beavers are absent, the cycle back to riparian health is the slowest, and longest lasting part of the whole cycle, sometimes taking millennia to rebuild stable sediment and the plants and animals it supports. However, with beavers present, this return to a “sponge-like” state can happen in a decade!


Given the plant communities of our watershed, it is likely that beaver dams were once found at a rate of at least 6 to 24 per mile of creek throughout all of the valley floor and far into the foothills and the gentler tributaries in the mountains. If we use a conservative figure of 15 dams per mile for the stretch of creek from its convergence with the Sacramento River to the point near the edge of the foothills where the three major forks come together, that would mean nearly 300 dams, each one slowing, spreading and sinking water. Assuming this went on for tens of thousands of years, it is no wonder that springs were abundant, riparian trees reached massive sizes, and animal numbers were staggering. Imagining that conjures up a massive, long wetland, full of tules and cattails and giant valley oaks, cottonwoods, willows, and yes, its namesake, elders.

Just as the presence of beavers can accelerate the aggredation (building up of stable sediment and riparian plants) of streams, their sudden absence accelerates the degradation of streams. In fact, stream incision can happen extremely quickly, washing away thousands of years of fertility in just a few years. The story around here, even repeated by the Resource Conservation District is that the west side creeks are much more flashy in nature, with extreme variation in flow. They say this is primarily because of topography and soil type.

But somehow, even with topography and soil that accelerate run-off, the riparian habitat along Elder Creek used to boast willows with girths of four feet across, and a few valley oaks still exist that are double that. This kind of growth happens when wide swaths of the land along a creek or river become sponge-like. Most likely, beavers created and maintained these semi-wetlands, and their sudden removal by fur trappers in the 1820s-1840s would have lead to a rather quick shift toward faster moving water in the rainy season and less flow through the dry season, thus deteriorating salmon and trout habitat due to warmer and shallower summer water.

So here we are 175 years since the beaver was either exterminated locally, or nearly so. By the time the creek started being monitored, beavers were effectively absent. No wonder west side creeks are known to be flashy and have small summer flows. It is not just the low amounts of snow in the Yolla Bolly Mountains (and all the other factors named on this site), it is also the loss of beavers, for without them, the water runs downstream much more quickly. Beavers were here long before humans and co-created the fecund world into which the Nomlaki were born. We would do all life in the watershed—including us humans—a big favor by encouraging their proliferation.

Also at the 2013 State of the Beaver Conference, Dr. Mary O’Brien from the Grand Canyon Trust, told how she has been working with ranchers to restore riparian habitat in a more arid (10 inches rain per year) climate than ours, and the aerial photos she showed said it all. Formerly narrow bands of vegetation along creeks after a century of grazing have returned to wide swaths of willows, cottonwoods and grasses after only a decade or two of improved grazing practices, particularly removal of the cattle during the dry season. And of course, beaver reintroduction plays a big role in this rapid transformation. Even in this arid land, restored creeks boast beaver dams that number from about 2 to 24 per mile.
Beaver BMPs
We really need to bring beavers back. Lots of them. Please write or call the California Department of Fish and Wildlife (use the link at lower right to email the Director’s Office), and tell them you want them to encourage the proliferation of beavers, specifically citing their critical role in stream restoration and salmon and trout recovery. You can also ask that they add a section on beavers to their “Living with Wildlife” page, citing the thorough example from Washington State’s Department of Fish and Wildlife. You could also mention that the New Mexico state senate recently passed a memorial recognizing the busy rodent’s value to water supplies and ecosystems—especially in times of drought. The beaver memorial acknowledges that the dams, ponds and associated wetlands created by beaver are known to increase groundwater percolation, which raises local groundwater tables and increases water storage. The memorial also recognizes the critical role that ecosystem restoration could play in protecting and recovering many imperiled species. As great as the New Mexico memorial is, Oregon and Utah already have statewide beaver management plans, both of which recognize the climate adaptation benefits beaver can offer. Let’s get California on board: tell Fish and Wildlife to protect and encourage beaver population restoration.

If you have issues with beavers, there are a number of inexpensive ways to work with them to avoid potential damage to your property or favorite trees. Download this Best Management Practices guide from the Grand Canyon Trust for details, or for a personal tale and even more detailed instructions, see this.

For a wealth of historical, anecdotal, and factual information about beavers, as well as the story of how the City of Martinez, CA has accommodated the return of beavers to their downtown, see Worth a Dam. Or, for a single article that summarizes the value of beavers to watersheds and this continent, see this from the Permaculture Activist or this from the Quivira Coalition.

Finally, the Wikipedia page on North American beaver is well-researched and accurate. The sections on beaver effects on stream flows, birds, anadromous fish and vegetation sufficiently capture why beavers are critical, not only to regenerating riparian communities of life, but also to our own long-term existence, for without them it would be much more difficult to truly live sustainably on this continent.

For a very good video demonstrating the benefits of beavers on a river with similar issues to our own creek, watch this.