Beaver Dam Analogue on Myers Creek, Okanogan County, Washington State Photo by Julie Vanderwal, Okanogan Highlands Alliance

WYOMING – Okay, most of us know or can guess why beavers build beaver dams. But why do biologists build beaver dams?

Game and Fish Department Aquatic Habitat supervisor Lara Gertsch explained the benefits of a time-tested stick jam on moving water.

Lara Gertsch

Beaver dams are important for streams. But, because some places aren’t good beaver habitat, biologists will build their own beaver dams. These are call beaver dam analogs, or BDAs for short, and they are a tool used by habitat biologists to mimic natural beaver dams.

These structures hold water, trap sediment, and stabilize the water flow. A beaver dam, whether analog or real, can help a stream that might only flow at certain times of the year keep water year-round, which is good for habitat, both in the water and on land, and is especially good for trout.

Biologists build the beaver dam analogs using wooden fence posts pounded into the stream bed with a mattress of willow or cottonwood limbs woven through the posts and mud.

“It’s almost like how a beaver would do it,” Gertsch said. “If the area is too remote for hauling in fence posts and post pounders, we just build it like a beaver. We use limbs, sod, mud, and logs collected from the site.”

Like a real beaver dam, analogs are temporary and can get breached if the water flows high and fast. Depending on the stream system and situation, the analogs should be expected to last up to five years or until the pool behind the dam fills with sediment and grows lots of woody plants.

Beavers do important work for the environment in reshaping habitat. (Wyoming Untrapped)