Surface Water Management Division
Beaver Management Program
Surface Water Management's primary role in beaver impact management within Snohomish County is to protect County right-of-way and County properties. We accomplish this by the use of non-lethal control methods including temporary dam removal or notching, various types of water level control devices and/or exclusionary devices.
For problems occurring outside of the right-of-way, SWM may provide limited technical assistance to property owners - consistent with the division's mission and within funding and staffing constraints.
This assistance may include advice, referrals, recommendations, technical information, training or demonstrations, informational materials and, in some cases, provision of (loaned or purchased) damage abatement materials. The recipient of this assistance is responsible for implementation of control measures.
Beavers, themselves, are regulated and managed by WDFW. Additionally, all construction work in streams, including dam removal or modification, requires a permit from WDFW.
Note: Snohomish County does not provide animal removal services.
Short History of Beaver Management in the Northwest
Across North America, there was an historical average density of 1.5 beaver per square mile
Beaver density in the Stillaguamish was estimated to fall between 0.6 and 2.5 beaver per square mile.
1805 - Fur trade in the Northwest was in it's infancy.
1821 - British company encouraged maximum harvest of wild furs to destroy fur resources in southern part of Northwest. As an example, 405,472 pelts were taken between 1834 and 1837.
1850 - Significant decline in fur harvest, with trappers turning to gold in California
1909 - First laws protecting beaver passed in Washington State
1963 - Trapping season for beaver re-opened due to statewide population abundance
According to WDFW an estimated 200-300 beaver were removed annually by recreational trappers from the Stillaguamish.
2001 – Statewide ban on use of body gripping traps.
Today, beaver pond habitat within the anadromous zone of the Stillaguamish Watershed has been reduced by over 86% from historic levels.
Life histories can be found at these sites:
Living with Wildlife, link to WDFW website.
Beavers Wetlands & Wildlife, link to a non-profit organization formed to help people live in harmony with beavers and other wildlife
Beaver biology and behavior, link to Missouri Department of Conservation Water Level Control Techniques
Water Level Control Techniques
Flexible Leveler (PDF download) This is our most commonly used solution.
Beaver Deceiver Plans (PDF download)
Used to stop dam building at culvert inlet
Needs to be trapezoid-shaped w/40 foot + perimeter
Passes fish when constructed as designed
Need to also guard outlet, see plans for details
Clemson Pond Leveler (PDF download)
Beaver Pond Control Structure (PDF download)
Beaver Diversion Dam
- Used when concerned only with plugged culvert
- Allows beaver to build dam without plugging culvert
- Easy to install
- No control of water height
- Provides fish passage
Beaver Food Preferences
Red Osier Dogwood
Repellents thought to be effective with beaver browse problems:
NOTE: Our trials have not shown any chemical to be effective. The only thing that has worked for us, is chicken wire or metal wire three feet tall.
Abrasive Paint - use exterior latex paint (with a color to match the bark) mixed with Mason sand (30 mil or 70 mil) in a ration of 5 oz. sand to 1 quart paint. Mechanically mix on the day of application.
Not effective in deterring beaver
Non-lethal beaver management for culverts and other surface water management facilities - link to King County website
Living with Wildlife: Beavers - Washington Department of Fish and Wildlife (external link to PDF document)
Managing nuisance beavers along roadsides - a guide for highway departments - NY Department of Conservation (PDF download)
Washington Department of Fish and Wildlife Fact sheet on Initiative 713 - trapping (external link)
The Beaver Handbook: A Guide to Understanding and Coping with Beaver Activity, Northeast Science and Technology, Natural Resources Canada, Ontario, Canada. The most complete and practical management book currently available (text not available online).
Ben Dittbrenner, Biologist, 425-388-3923
Nuisance Wildlife Enforcement Program
Washington Department of Fish and Wildlife
600 Capitol Way N.
Olympia, WA 98501-1091