Beaver Dam Analogs (BDA): A Hands-On Approach to Iowa Steam Restoration
Beaver Dam Analogs (BDA’s) are a human-made structure that mimics a beaver dam. These can be used to attract beavers to an area, or mimic beaver behavior (improving aquatic ecosystems) in an area that may not be accessible or suitable for beaver to live and thrive.
Beavers play a critical role in maintaining healthy wetland ecosystems by creating ponds that support rich biodiversity. BDA’s are not a replacement for beavers, but a stream restoration tool we can use to help us help the beavers do what they do best!
It goes without saying, human activity has led to many streams losing their natural beaver populations and along with them, the benefits they provide like filtering runoff and providing habitat for fish, ducks, snakes, muskrats, herons (the list goes on!).
That’s where beaver dam analogs (BDAs) come in, allowing us a new method to help restore our waterways. In my practice, I use BDA’s to attract beavers to a stretch of stream where they currently are not present. I included the graphic below, which does a beautiful job of briefly summarizing the groundwater benefits and why we need them and the wetlands they create!
What are Beaver Dam Analogs made of?
BDA’s are constructed using the same materials a beaver would. I usually start with wood posts, and then the rest of the material can be found nearby, like mud, sticks, and logs. There are two ways we make BDA’s. The first, being by hand, and the second, with a mini excavator. They will each look a little different, as the by-hand method will have posts and be filled with sticks, and the excavating method will likely grow more vegetation and be more dirt-based.
Why Use Beaver Dam Analogs?
Erosion Control: By slowing down water flow, BDAs reduce erosion, stabilizing stream banks and preventing loss of valuable topsoil.
Water Storage: These structures help retain water during dry periods, improving drought resilience for surrounding ecosystems and plants. BDA’s encourage backwatering and frequent overbank flooding, which over time recharges shallow groundwater and increases storage of groundwater. BDA’s (same as beaver dams!) work to detain floodwaters and spread higher flows across a floodplain.
Habitat Creation: BDAs promote wetland ecosystems that support a diverse amount of amphibians, birds, and insects. We are learning more each year about different endangered plants that also benefit from beaver presence.
Improved Water Quality: By allowing sediment to settle and filtering pollutants, BDAs enhance water quality in nearby streams and rivers.
Constructing Beaver Dam Analogs
I always start by doing a careful site assessment. Any time you are working on a stream, it is important to understand how the water moves at it’s highest.
Gathering and Organizing Materials: We use locally sourced branches, logs, and stones to ensure that the structures harmonize with the existing habitat.
Building the Structure: Using a method similar to what beavers would do, we stack and weave materials in a way that creates a sturdy barrier. This involves getting pretty muddy, so make sure you have a pair of waiters and a good pair of gloves unless you want mud under your fingernails for the next two weeks!
Monitoring Success: After construction, we monitor the site to assess the BDA. Depending on the site, sometimes we use BDA’s in areas where beaver will never be able to access. Therefore, the BDA will need to be maintained by a non-beaver human :-) Other times, we monitor until we find sign that a bachelor swam upstream and found our BDA as a worthy project to maintain for us!
Get Creative: Every site is a little different! Read below about how Gordon has gotten creative on his property.
Success Stories: The Impact of BDAs
Gordon of Emmet County has successfully built and maintained over three BDAs on his property. Some of which, beavers have moved in to maintain. Others, he hopes they will begin to maintain soon. Gordon can implement BDA’s skillfully in areas he knows he wants or needs ponds. By working with beaver in this way, you can strategically plan ponding/wetland habitats rather than the beavers fully deciding for themselves. Which, they are the true wetland ecology experts so even with BDA’s, they may decide you need a wetland in exactly the spot you least expected.
One of Gordon’s BDA’s (now maintained by beavers) in the winter. As you can see, beavers are great at weaving sticks in.
“My BDA’s are somewhat different in that I use dirt with spillways protected with brush or hay bales. The object is that the main dam will remain protected by vegetation during extreme rain events and the smaller, easily repaired spillway will suffer the damage instead. Peak flows do not last long because this is a headwater creek.” Gordon explains.
Gordon has a truly impressive property rich with beaver habitat. The amount of wildlife on Gordons property is truly astounding. Where beavers are, wildlife follows. Odds are if you found this blog or are on this website, you are also a wildlife lover. If you have a stream on your property, reach out to us about installing a BDA to increase specifies diversity. Having a beaver pond, down the road, can open the door to many other conservation projects like installing threatened wetland plants and working to have an active wetland on your property! And the best part is: beavers will do most the work for free!
Getting Started with Your Own Beaver Dam Analog
BDA’s is absolutely something you can implement on your own on your property. However, before beginning, consider seeking our professional guidance to ensure the effectiveness and to stay in line with local regulations.
Beaver dam analogs are a testament to how we can leverage a beaver’s ingenuity to help restore and protect our Iowa ecosystems!
If you're interested in learning more about effective stream restoration techniques, please reach out to info@sownecologicalsolutions.com
