Frequently Asked Questions about Beavers
There are a lot of questions people have regarding beavers. The pages of this website cover many topics, such as the benefits of beavers and solutions to problems, so that information is not repeated here. This page is intended to capture questions that we hear frequently that are not otherwise addressed in this website. Have a question that's not here? Let us know.
Top 3 Concerns Related to Beaver Dams
Beavers and salmon have co-existed for thousands of years. One of the reasons the relationship works is because the timing of the spawning runs typically coincide with fall and winter increases in rainfall, which increase stream flows. Before the rains increase flows, salmon may hold in front of a beaver dam waiting for the flows to rise. During fall rainstorms, water often flows over beaver dams, and that’s the ideal time for the fish to pass them. Smaller salmon have also been known to get through holes in the dams.
How do we know salmon get past beaver dams? Not only do we see adult fish above known dams, but beaver ponds are well-documented rearing habitat for juvenile coho salmon. The only way juvenile salmon could get in the ponds is if the adults made it past the dams in the first place.One significant exception to this rule occurs when beavers plug culverts. A culvert is essentially a hole in a large, solid, man-made dam. When beavers plug a culvert, it does likely block fish passage. Culvert fencing may be used in combination with flow-control devices to keep beavers from being able to block culverts. For more information on these types of engineered solutions, see Problems and Solutions.
Contrary to what may seem logical, beaver ponds do not increase water temperatures downstream. At least not in some parts of Western Washington. Even though beaver ponds constitute relatively large, shallow open water areas that often cannot be fully shaded because of their size, the hydrologic processes occurring between the pond, groundwater, and the stream serve to lower water temperatures in many instances in the Pacific Northwest.
One local study showed that because of the influence of groundwater, the water temperatures below beaver ponds was 2.3 degrees C lower than the water temperature of the same stream above the beaver pond.
Yes. Beavers build dams to raise water levels and create ponds. When the water from the newly raised pond flows over land with human infrastructure, agriculture, lawns, and other human uses, that's what we call flooding.
Fortunately, there are ways that humans can manipulate the dams in many instances to control water levels and keep them from flooding adjacent areas. These “beaver management devices” have various names: flow-control devices, pond levelers, flexible levelers, and more. They all have the same purpose: to allow some water to flow undetected (by the beavers) through the dam and to maintain the pond height during ordinary flow conditions at a level acceptable to concerned people. (The devices are not designed to maintain water levels during high flow conditions.)
The pond levelers are typically made of a corrugated PVC pipe running from the pond through the dam to the stream below. The upstream end of the pipe is fenced to keep it from being plugged by the beavers. The height of the pipe controls the height of the water in the pond at normal streamflow. It is a simple and effective technique, but the devices must be maintained. Maintenance schedules vary widely depending on site conditions. Additionally, there may be instances when the resident beavers decide to build another dam upstream or downstream of the device. Every situation is unique. View the Resources page to learn more about your options.
This answer does not address beaver dam failures and flooding that results from them. When dams get old enough, the material they are made of may become rotted or unstable. If you are concerned about the potential failure of a beaver dam on or near your property, contact King County Drainage Services.
Yes, you may, but there are permits required by Washington State Department of Fish and Wildlife and possibly from King County Department of Permitting and Environmental Review.
To remove or modify a beaver dam you must have a Hydraulic Project Approval (HPA)—a permit issued by WDFW for work that will use, obstruct, change, or divert the bed or flow of state waters (RCW 77.55). A permit application can be obtained from your WDFW Regional Office or from the Hydraulic Project Approval (HPA) web page.
A King County Clearing and Grading Permit is likely required by the Department of Permitting and Environmental Review. Currently, a determination is made on a case-by-case basis. In the future, additional guidance will be established. But until then, if you are in King County, contact DPER at 206-296-6600.
The beaver is classified as a furbearer by WDFW. A trapping license and open season are required to trap or shoot a beaver. The trapping season is set from November 1 to March 31.
Yes, and in fact, according to WDFW, “Persons purchasing a state trapping license for the first time shall present certification of completion of a course of instruction in safe, humane, and proper trapping techniques or pass an examination to establish that the applicant has the requisite knowledge.” Visit this WDFW Trapper Education webpage for more information about when and where. WDFW has also provided this informational booklet on Trapper Education in Washington State.
Yes. Typical baits are freshly cut tree sprouts or branches, as well as commercial scents and lures.
When the trapping season is closed you may not use any bait or scent.
A list of Wildlife Control Operators may be found at the WDFW webpage
A wildlife control operator (WCO) is an experienced and professional trapper who has successfully completed WCO training and obtained one or more levels of certification from the Washington Department of Fish and Wildlife (WDFW) in order to handle nuisance wildlife issues and charge a fee. Wildlife Control Operators are certified through WDFW and must conform to its regulations, but they are not state employees and operate as private entities.
Trappers charge a set-up fee plus a fee per caught beaver, and trappers set their own prices. A colony typically has 2 to 6 beavers. If all the beavers are not removed then the remaining individuals will continue to fell trees and maintain their dams. There is no guarantee that even if you remove all the beavers from a site it will not be recolonized within the next 2 to 12 months.
A list of Wildlife Control Operators may be found at the WDFW webpage
Wildlife Control Operators “provide direct assistance to landowners who are willing to pay for the cost of certified individuals to resolve their wildlife problems. Under the authority of their permit from WDFW, WCOs are able to use specified types of traps to capture and dispose of certain wildlife year-round,” including the following small game/furbearer species when causing damage to private property: raccoon, fox, bobcat, beaver, muskrat, mink, river otter, weasel, hare, and cottontail rabbits.”