Beaver Dam Analog Building
Busy as a Beaver?
Yes I was, along with a dozen or so other volunteers led by Hans Stehenson of Dakota Angler & Outfitter at the Back Hills Beaver Dam Analog (BDA) project on July 20-21. Because there are beavers on our property south of Denver and I have watched them build dams here for the last 20 years, as well as watched those dams wash out in spring storm events, I am fascinated by these structures.
BDA’s are used for many purposes, including mimicking the benefits real beaver dams bring to an ecosystem and enticing beavers to continue the work. Building BDA’s is both art and science and there is no substitute for experience and practice. I was able to spend only one full day at the site but learned a tremendous amount. A few of my key takeaways were:
Primary components are vertical wood posts, chunks of sod about one cubic foot each, and coniferous branches 4-8 feet long. The posts are in parallel rows and closely spaced. The branches and sod chunks are placed in alternating layers.
It takes a tremendous amount of raw material to make even a small BDA, and therefore volunteer labor is essential.
The number of vertical posts needed is far more than I would have assumed. I counted approx. 40 Douglas fir posts in one dam that was about 25 feet wide.
Our location south of Denver would require a very different design because we don’t have abundant fir and spruce saplings that we can cut and incorporate. Our supply of available sod is also much more limited.
I think it’s safe to say that all of us who participated on this BDA project in the Black Hills near Lead, SD, felt a sense of satisfaction at the end of our workday. As I reflected on it later, I realized that it was a perfect example of Regenerative Design in action. Although I have written about and spoken on Regenerative Design, it can be difficult to point to actual examples of human activity that lead to net improvement in the natural environment. Building BDA’s in the Back Hills and restoring a healthy balance between land and water, may be the closest I have come to it!