Rapidan Institute SoilKeepers Virginia Wildlife Habitat Cooperative

Building Beaver Dam Analogs (BDAs)

Beaver dam analogs, also known as BDAs, are man-made structures built out of wood and other natural resources designed to replicate the form and function of beaver dams. ACP began working on BDAs this year with the intent to help restore freshwater ecosystems and make possible habitats more suitable for beavers. Being that BDAs are mostly made of natural materials, they are a relatively simple and cost-effective restoration project. Before getting started with BDAs it is important to note these structures are not designed to last forever, they are merely temporary structures that may last anywhere from a year to a decade. Ultimately, the goal of BDAs is to help improve the quality of freshwater ecosystems while simultaneously attracting beavers to the area. Once beavers have settled in they take over the responsibilities of the BDAs and continue their work from there on out. 

The first step in establishing a BDA is to determine an appropriate location. Beavers prefer to build dams in slow-moving water that is surrounded by woodland and herbaceous vegetation. When constructing BDAs it is common practice to first build a larger BDA that can withstand more force with several smaller BDAs downstream. This helps form deeper pools of water and slows the overall movement of the water through the dams. When constructing BDAs it can be helpful to drive untreated wood posts into the bottom of the stream or river in an aligned fashion, if the geology in the area allows for it. From there, branches, sticks, logs, and rocks can be placed around the posts to help develop the structure of the BDA. In the BDAs pictured below, we used the log method to stack the untreated wooden posts in a V-shaped fashion. Both methods are equally effective when it comes to constructing BDAs. However, with this project, we felt it was best to use the log method as we were working in a stream with a rocky bottom. Additionally, it can also be helpful to incorporate vines as they can be weaved in between the building materials to help hold everything together. After the main structure is built the last thing to do is shovel mud and sand around the base of the BDA to help secure it in place. In my experience with BDAs I have found it’s a great time to be resourceful, so feel free to use and experiment with whatever natural materials are around you! 

BDA constructed by CNC in Marshall, VA
Dan Paparella standing next to a BDA we constructed