Beaver Restoration & Coexistence
Think like a beaver! There are many ways to reap the benefits that beaver (and beaver-inspired processes) provide – while avoiding potential nuisance and conflict – through non-lethal management, enhancement, mimicry, and more.
Why Beaver?
Beaver are nature’s great ecosystem engineers. They are native to and were once prevalent throughout California. As we grapple with our water woes in the arid West, we can take inspiration from their behavior to recharge and restore our degraded watersheds.
Beaver dams improve water quality, repair eroded channels, reconnect streams to their floodplains, and create ecological complexity and diversity in otherwise simplified or degraded stream systems. Beaver dams, canals, bank lodges, and discarded stick piles greatly expand wetland and wet meadow habitats and provide many other ecosystem benefits to imperiled fish, birds, and amphibians by prolonging critical summer streamflow in degraded streams that would otherwise run dry. The scientific literature indicates that beaver dams and associated ponds help mitigate the impacts of climate change, drought, and wildfire through sequestering carbon, increasing surface water and groundwater storage, attenuating flood waters, and creating what Dr. Emily Fairfax calls green “ribbons of fire-resistant riparian corridor” that serve as critical “refugia” for species to escape fire. By creating conditions that keep beaver on the landscape and/or taking our cues from their engineering skills (also known as “mimicry”), we can put their fastidious work to good use!
Beaver restoration is considered a form of process-based restoration: low-tech, nature-based solutions that harness natural energies and cycles to accomplish restoration goals.
Coexistence through non-lethal management
While some landowners appreciate beaver’s presence, others are frustrated by what they can do to the landscape. The most common complaints come from beaver dam-building in streams or blocking culverts, irrigation ditches, or water conveyance structures, causing flooding and/or flow disruptions. They also burrow into levees and dam walls and cut down trees and other valuable vegetation. Most of these activities can be managed with low-cost, easy-to-install strategies that prevent property damage and avoid the need to kill beaver, while retaining the many benefits beaver bring.
Here’s how to manage some of these common problems:
As beaver build dams, the rising water can cause flooding. Notching and/or removal of dams are ineffective responses as beavers will typically attempt to rebuild. Additionally, these activities encourage the beaver to harvest more vegetation, causing greater impacts on the riparian habitat.
To manage water height, property owners can build or install a flexible pond leveler. This device prevents a beaver’s dam-building behavioral cue – the sound and feel of running water. Because beaver have an instinct to build when they hear running water, it is a losing battle to simply remove their dams. Instead, putting a pipe through the dam prevents water from noisily spilling over the top, which discourages the beaver from building the dam any higher. A welded wire cage around the submerged upstream inlet keeps beaver from blocking the pipe. The pipe releases water below the dam crest on the downstream side, reducing dam-building cues. The installer can then lower the pond to the level that reduces flooding, ideally while retaining the beaver and their associated benefits.
For more information, visit The Beaver Institute’s page on dam flooding.
When culverts are installed in waterways in their habitat, beaver will often block the flow of water through the culvert. There are several strategies to prevent blocked culverts:
- Trapezoidal fence: An easy way to prevent beaver from blocking the culvert is to build a trapezoidal-shaped fence that is narrowest at the culvert and widens upstream. This forces the beaver to dam a much larger area, and as the dam grows along the fence, it gets farther and farther from the stimulus of water rushing to the culvert. Keeping the culvert open this way prevents the roadbed from becoming oversaturated or the road from washing away completely. A pond leveler pipe can also be run through the fence if needed.
- Fence and pipe device: This device is the same as a pond leveler.
- Starter dam: A starter dam can be built with fencing or natural materials such as rocks, wooden posts, and branches. Starting a dam 10 to 15 feet upstream of the culvert encourages the beaver to build on the starter dam instead of the culvert.
For more information, visit The Beaver Institute’s page on blocked culverts and drains.
The Beaver Back Saver eliminates the need to constantly clear out of twin track weirs of debris from beaver activity. The retrofit slides onto an existing weir, drawing water through a perforated pipe capped with a metal grate, allowing the weir to convey water without beaver hearing or sensing the flow, thus deterring them from plugging it up. For more information and a how-to, see our Beaver Back Saver project.
Trees can be protected either individually or in groups. In most places, wrapping trees with a four-foot-high (two-inch by four-inch) galvanized welded wire is sufficient. Make sure the wire completely surrounds the tree and leave a 12-inch space all the way around the tree to allow for growth. In areas where it snows, using taller fencing that will reach about two feet above the average snow height is important to ensure year-round protection. Chicken wire is not strong enough to withstand rust and collapse. Some people use one or two strands of solar-powered, portable electric fencing set at beaver height to prevent them from accessing vegetation.
Another option for tree protection is to paint the tree trunks with a mixture of exterior latex paint and coarse sand. Paint does require more maintenance and reapplication but can be color-matched to the tree bark to blend in well and address aesthetic concerns. To every gallon of paint, add 20 ounces of mason sand (30-70 mesh). Mix well and make only what you can use. Remove debris from the tree bark before applying the paint, and be careful not to apply too thickly or the sandy paint will roll off. Cover the entire section of the trunk that runs from the ground level to two feet above the anticipated snow level.
Lethal management should only be considered the last resort, as it can cause bad public relations and be costly and ineffectual in the long run. No matter how many beaver you kill, if the habitat is favorable and there are other colonies nearby, they will continue to return. Recognizing the ecological and economic value of keeping beaver in place, the California Department of Fish and Wildlife (CDFW) instituted a new policy in 2023 that supports non-lethal strategies when possible. It also considers the impact beaver removal could have on endangered species. However, beaver dam removal is beyond the scope of its policy at this time.
Enhancement, Expansion, and Mimicry
Enhancement, expansion, and mimicry are key strategies in beaver restoration efforts, aiming to capitalize on the natural behaviors of beaver to promote healthy ecosystems.
Enhancement includes reinforcing beaver dams and adding human-made beaver dam analogs (BDAs) and other in-stream structures to increase the duration of dams and their benefits. In working landscapes, installing fencing to protect riparian areas and changing grazing regimes reduces competition for food. These actions support beaver in persisting and contributing their ecological benefits; more water in the landscape provides livestock more forage and water longer into the dry season.
One can entice beaver to increase the wetland area they create and maintain by removing obstacles such as levees and/or adding beaver dam analogs (BDAs) and other beaver-like habitat modifications. Planting foods beaver favor, including willow, cottonwood, aspen, cattails, etc., can entice them to expand into areas you would like them to occupy.
In places where beaver do not live, building beaver dam analogs (BDAs) and mimicking other beaver-like habitat modifications can accelerate efforts to create and maintain wetlands and restore meadows and streams. Without beaver, these structures and ecosystems can require a different level of ongoing engagement.
Relocation
Relocation involves trapping live beaver from places where coexistence methods have been exhausted and reintroducing them into suitable locations. Due to reduced chances of surviving the relocation process, beaver should only be moved from places where lethal management in response to damage would otherwise be unavoidable. CDFW is the only entity allowed to legally carry out beaver relocations.
California’s new Beaver Restoration Program completed its first relocation in October 2023. See the CDFW press release here. We were honored to be invited by CDFW and the Maidu Summit Consortium to participate in this momentous return of beaver back to Plumas County, in an area that is known to the tribal community as Tásmam Koyóm. In June 2024, we were honored once again to participate in a beaver release at the Tule River Reservation. CDFW carried out this historic beaver back moment in collaboration with our Tule River Beaver Project partners.
Case Studies
Below are examples of each kind of beaver restoration. Note that several examples use more than one type of restoration.
- Fryer Creek (coexistence)
- El Dorado Hills (coexistence)
- Caltrans District 5 (coexistence)
- Doty Ravine (coexistence, expansion, enhancement, mimicry)
- Scott River Watershed Council (mimicry)
- Tásmam Koyóm with the Maidu Summit Consortium (mimicry and relocation planning and implementation)
- Stemple Creek (mimicry)
