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When people in King County think of beavers, they often think of problems. Because beavers are a misunderstood group of rodents, we want to clear up some misconceptions. The following statements are all true for natural systems, contrary to popular belief:

Beaver by a pond

  • Beavers do not cause deleterious streambank erosion 
  • Beavers do not cause streams to silt up
  • Beavers do not cause salmon catastrophes
  • Beavers create excellent rearing habitat for some salmonid species
  • Beavers help form wetlands that attract wide varieties of plant and animal species
  • Beavers help reduce the extreme of both flash flooding and dry stream

The truth is beavers do a lot of really good things for the natural environment. Problems arise because humans live in and commute through areas where beavers still have an impact, such as where beaver ponds and roads come together.

How beaver problems develop

Normally when we build roads, if a stream passes through the area, we place a culvert under the road large enough to hopefully support the flow of the stream. But, enter one beaver and everything changes. Let's say it's a 2-year old male, he's just left his natal pond, and he is looking for a place of his own. He finds a nice low-gradient stream with no other beavers and with plenty of trees and vegetation for food, and he decides to start building a dam. The dam allows the water levels to rise so the pond is deep enough to provide cover from predators. The beaver's instinct is to stop any rushing water, because the sound of rushing water tells him precious water is escaping. He sets to work to stop the flow by damming up the culvert. And pretty soon he's got a nice pool deep enough to hide in, maybe build a lodge in, and maybe find a mate and start his own family. The stream continues to flow from the headwaters but no longer has a clear passage to exit under the road. The water eventually starts to flow over the road. And now we've got a public safety issue.

It is not the mere fact of beaver presence that creates problems. It is the combination of beaver and the infrastructure people rely on to make their lives run more smoothly.

Some relatively recent occurrences in Washington State include a voter-approved ban on all "body-gripping" traps. Revised Code of Washington (RCW) 77.15.194 provides definitions and penalties associated with use. By some accounts, the number of beavers trapped in the state of Washington has decreased by 80 percent since 2000. If we assume all other factors are equal, the reduction in trapping means there are lots more beavers in our systems than there were just 15 years ago.

More beavers in the Northwest means more potential problems. More problems will require a willingness on the part of more landowners to learn how to manage beavers. More problems will require more solutions. Beavers are excellent engineers, but people can be quite ingenious as well. And when problems with beavers arise, there are many approaches to take that might provide solutions that will allow man to live with beavers. 

What about Solutions?

If your problem is flooding, there are many engineering solutions available. For example, you may install a water level-control device, which allows the beaver to stay on location while water continues to flow downstream. If your problem is losing your trees and shrubs, there are a few approaches you might take so that you, your vegetation, and the local beavers may all co-exist. Now that we've covered problems, let's talk about solutions. It is far more gratifying to learn about solving problems!