How beaver problems develop

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:

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

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. Let's look at the combination of beaver ponds and roads as an example.

Normally when we build roads, if a stream passes through the area, we put a culvert under the road big enough for the flow of the stream. Enter one Beaver. Let's say it's a 2-year old male, just left his natal pond and is looking for a place of his own. He finds a nice low-gradient stream without other beavers and with plenty of trees and vegetation for food, and he decides to start building a dam. After all, he needs water deep enough to provide cover. His instinct is to stop the rushing water, for it is the rushing sound that tells him his precious water is escaping. He sets to work to stop that flow: he dams 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. It eventually starts to flow over the road. Now we've got a public safety issue.

As we hope to make clear, it is not the mere fact of beavers that creates problems. It is the combination of beaver with man. The following article gives a broad overview of the impacts of humans on beavers, beavers on the land, and the loss of beavers in natural systems. The Benefits of Beavers by the National Parks Conservation Association is a great article for information about historical beaver populations and their ecology.

Some more 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% 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 a mere 5 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 are pretty 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.