Fooling Nature's Engineers: Beaver Deceiver 101

installed beaver deceiver

Beavers are an essential part of many North American forest and wetland communities. They are ecosystem engineers, meaning they play a role in altering the landscape and increasing biological diversity with the impoundments they create by building dams.  

A typical view upstream of a beaver dam found in Durham, NH.

While they are beneficial to so many other species, one other ecosystem engineer has taken issue with beavers and their impacts: humans. For centuries, settlers trapped beavers for their fur and hunted them down to less than 1% of their current population. With reintroduction and management efforts, beavers have rebounded, but now have a new conflict with people. Beavers are hardwired to dam up flowing water and sometimes that is problematic when it infringes on areas that we’d prefer to stay dry –like the roads and trails we use every day. 

Enter - The Beaver Deceiver

fence in water
At Thompson, a path was being flooded right next to the dam, so this H shape is PVC with holes and a pipe running under the path was chosen to use and be less disruptive to foot traffic.

Breaking down dams is tiring, muddy, and unsustainable. Rather than killing these beavers or relocating them, there is another way to resolve this situation so beavers and humans can coexist: the beaver deceiver. There are different designs, but each consists of a pipe that runs from one side of the dam to the other with a mechanism that will block beavers from plugging it up. Ideally, the pipe will be underwater so the beavers can’t hear the trickle that usually would call them to action. This allows the water level to be maintained so it won’t flood roads or trails while the ecosystem the beaver built can also endure. This summer, we (the Nature Groupie Interns) got to help fix one at Thompson Farm in Durham and install a new one upstream of Mendum’s Pond in Barrington. 

beaver deceiver on truck bed
At Mendum's Pond a road was flooded by beavers so this larger pipe was used.

Installing the Deceiver

There are a few steps to installing a beaver deceiver. First, it must be constructed. The design should be chosen based on the site and goals. 

intern using tool to remove beaver dam
Before doing work in the pond it helps to break the dam to lower the water using a shovel, rogue hoe, or Pulaski.
people standing at beaver dam talking
Once the pipe fills with water it will become nearly impossible to move, so you must spend some time envisioning rather than doing trial and error later. Here is our team discussing the installation before.

Once the pond is drained, you will need to keep your digging tools handy and bring in wire, wire cutters, pliers, fencing, fence posts, sledgehammers, and waders. Then it’s time to get in the water and start getting materials in position. Once everything is in place, you will have to secure it with posts and wires.  

people installing pipe
Make sure that the beaver can't get at the pipe - whether that means fencing it off like the H design above or covering the open end of the culvert with fencing like in this photo.

Done Deceiving

The level of the pond should not exceed the level of the output side of the pipe if everything goes according to plan. At the end of the process, the beaver will fix the hole in their dam, the water level will stabilize, and it will be business as usual in a pond that is at a happy medium for everyone.