Beaver & Wetland Survey

Beavers were hunted to near extinction by the European fur trade with their arrival in Oregon in the 1800s. While populations in low-lying areas have begun recovering, beavers continue to be killed in large numbers by individuals, federal and state wildlife agencies. For the past 3 years, Bark has been working to bring beavers back to their rightful place on Mt. Hood.

Beaver are a keystone species, meaning many other species rely on the beaver to thrive. Beaver can build complex pond systems that provide important wetland habitat while simultaneously slowing the movement of water over the landscape. These resulting beaver ponds help to recharge aquifers (groundwater) while also protecting juvenile fish and preventing erosion during high flow events. 

Mt. Hood National Forest is the source of domestic water for more than one million people, as well as being a critical freshwater habitat for a suite of aquatic species, including the culturally-iconic and threatened salmon and steelhead.

The presence of beaver can improve water quality, mitigate effect of climate change, and restore habitat for many animal species including andromonous (migratory) fish like salmon and steelhead. 

Bark began working to restore this keystone species to the forests surrounding Mt. Hood in 2018 with Portland State University senior capstone projects.  Since then Bark has continued work surveying potential beaver habitat, mapping wetlands in Mt. Hood National Forest, and working to estimate water capacity of wetlands to understand which wetlands can provide the most restoration with reintroduction of beavers. 

Bark is also working with several groups across the state to end beaver hunting and trapping on federally managed public lands, so this ecological engineer can do the work necessary to increase water security in our region. You can learn more about this effort here. 

How do beavers change their environments? 

Beavers change their habitats to make suitable homes from themselves. They use mud, silt, and sticks to create dams and build lodges.  Beaver dams create ponds which can increase the surface area of water several hundred times. This increases riparian areas and wetlands and from streams and can restore riparian areas and watersheds by increasing the complexity of those systems.

Diagram courtesy of Cascadia Wildlands

What effects do these changes have? 

  • Erosion Control: Beaver ponds expand riparian (river & stream) vegetation by expanding water available for wetland and riparian plants.  This increased vegetation along stream banks protects against erosion leading to better water quality for human use and better habitat for the salmon and steelhead in those streams. 
  • Improve stream temperatures: Currently ODEQ has thousands of stream miles listed as water quality impaired for temperature. The rise in water tables in beaver dominated meadows results in increased groundwater contributions to streams and ponds. When combined with deeper pond water depths, the result is a decrease in stream temperatures. This decrease can, in some cases, result in the stream or a segment of the stream being delisted. 
  • Habitat Creation: The ponds and meadows created by beavers enhance habitat for game species like ducks, deer & elk as well as improve migratory bird habitat.  Expanded beaver ponds, wetlands, wet meadows and structurally complex and diverse riparian habitat across the state provide increased food sources, habitat resting areas, and rearing areas including snags for cavity nesting species. Benefits threatened, sensitive, and declining species like the Willow Flycatcher, Yellow Warbler, Song Sparrow and Yellow-breasted Chat. 
  • Salmon Recovery: The abundance of adromous fish, including salmon and steelhead, has been adversely affected by dams, overharvest, hatchery practices, habitat degradation, and will soon be affected by climate change.  The late-run coho salmon Clackamas River along are considered the last remaining viable wild coho population in the Columbia Basin.  The changes beavers make to their habitat can aid in salmon recovery in a number of ways: 
  • Improves Andromonous (migratory) Fish Habitat: Andromonous fish benefit from clean and clear water, deep pools, low water flows, and woody material in water.  Beaver presence contributes to all of these factors. 
  • Improves rearing habitat:  Rearing habitat has been identified as a hey limiting factor to salmonid species and beaver ponds have been identified as a key source of rearing habitat.  As they provide, adequate food and a protective environment for salmon growth and survival 
  • Beaver’s effects on the environment are similar to the work that many agencies have done to restore riparian habitats and improve water quality and quantity.  Beaver-created restoration is self-maintaing and self-enhancing as beavers continue to be around to repair dam breaches.  Using this approach to restoration minimizes spending on the repetitive and reoccurring costs of maintaining restoration efforts so that dollars would be available to focus on species and restoration efforts in areas not influenced by beavers. 

Beavers as Climate Change Mitigation 

Current research predicts that climate change will severely alter precipitation and temperature patterns in the Pacific Northwest by midcentury, resulting in both more flood events and drought in forested ecosystems. On the Clackamas watershed specifically, river flow has already shifted to greater rain-driven flows and less snow-melt driven flows. This combined with less summertime flow is a significant concern for both drinking water and salmon habitat. These changes are projected to be most prominent in the highest elevation watersheds, where flows are currently most dependent on winter snow accumulation. By working proactively to defend and restore the natural processes of the forest ecosystem, we can mitigate the local impacts of climate change on Mt. Hood’s watersheds. 

How do beavers mitigate the effects of climate change? 

  • Improves water security and quality for municipal, ranching, and agricultural users. Beaver dams, ponds and resulting wetlands and wet meadows increase temporary surface water and groundwater in the headwaters resulting in water being more slowly and sustainably released. This stabilizes river flows during droughts and damaging flood events, recharges aquifers, and helps to offset the impacts of drought and decrease the frequency and magnitudes of downstream flooding. Abundant wetlands and ponds lead to improved water quality (i.e. cooler stream temperatures, less sediment) because beaver ponds and dams act as a giant water filter, resulting in cleaner water downstream.  Restoring beaver populations is important as water coming from national forests is used as drinking water for a large percentage of Oregonians and contributes to water used for ranching and agriculture. 
  • Creates carbon capture and storage areas. Wetlands and wet meadows extract carbon from the air and store it in roots and decaying matter below ground, and in the abundant riparian vegetation above ground. Beaver ponds also capture and store carbon as dead vegetation is submerged under water.  This natural process of carbon capture and storage related to wetlands, wet meadows and ponds directly addresses climate change and is currently an underutilized climate change response strategy.   
  • Creates wildfire safe zones for wildlife and livestock and aid in post-fire recovery.  An increase in size, severity, and frequency of wildfires is expected and currently seen with climate change.  The increase in abundance, size, and distribution of wetlands, wet meadows, and ponds across the state creates safe zones during wildfire for wildlife and livestock to retreat to. Forage and habitat recover more quickly post-fire than upland vegetation because of the presence of abundant water and the fact that many riparian plants are fire-adapted and respond favorably to the disturbance. Beaver ponds and wetlands/wet meadows help maintain downstream water quality by trapping sediment that might erode off hillslopes post-fire. 

Bark is supporting the return of beavers to Mt. Hood in several ways: 

  • Bark is working with Portland State University and the U.S. Forest Service to identify & prioritize existing and potential habitat in Mt. Hood National Forest that could support the reintroduction of beaver. If you are interested in participating in this work, learn more about volunteering here.
  • Working to more accurately map wetlands in Mt Hood National Forest.
  • Estimating water capacity of wetlands to understand which wetlands could most benefit from beaver reintroduction
  • Endorsing the closing or decommissioning of unnecessary and ecologically damaging logging roads which could fragment beaver habitat or create future conflicts if deteriorating culverts (drainage tunnels) are instinctively plugged up by beavers attempting to create a new home
  • Working with the Forest Service to identify & replace undersized road culverts and installing beaver-friendly structures, which prevent unwanted flooding
  • Restoring distributions of beaver-preferred plant species like willows through informed re-planting in degraded areas (this vegetation is both eaten and used in beaver dam and lodge-building)
  • Advocating for an end to lethal removal of “nuisance beavers” in low-lying areas, and instead, making the case for re-location of these animals to areas they previously inhabited on federal forest lands
  • Advocating to end the recreational and commercial trapping of beaver on federally managed public lands in Oregon.

We need your support in our efforts to help beavers return to Mt. Hood!

Plug into Bark's volunteer opportunities for Beaver Habitat Survey and Restoration page. Also, please consider sending a letter to your state and federal legislators, urging them to end beaver trapping on federally-managed public lands.

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