Replicating the ecosystem benefits of beaver dams

Farmer bending over, pulling and piling plants

6M-12 M

The current North American beaver population, which has shrunk since the 1600s.

When beavers construct dams that partially block streams and rivers, the diverted water collects in ponds in which these animals can build safe homes away from predators. Beaver dams also cause the saturation of nearby land, where a multitude of wetland species can thrive. But the North American beaver population, which exceeded 100 million in the 1600s, has fallen to between 6 and 12 million today; with fewer beaver dams, fewer streams in the western US are connected to their surrounding landscape.

For Montana-based rancher Amber Smith and seven other ranchers, the remedy to this situation was to create Beaver Dam Analogs, or BDAs—with help from the Montana Conservation Corps and WWF’s Sustainable Ranching Initiative. On Smith’s ranch, stabilizing posts hold sod and conifer and willow branches in place across the width of streambeds. The result: More water remains on site, fostering greener grazing grass and a more stable environment for pollinators and native endangered species.

And although true beaver dams would be the best, Smith says, “Implementing BDAs allows us to extend the time of green growth. And anytime you have photosynthesis taking place on your property, it’s a good thing—whether it’s for horses, cows, or the deer who just walk by.”

Explore More

World Wildlife magazine provides an inspiring, in-depth look at the connections between animals, people and our planet. Published quarterly by WWF, the magazine helps make you a part of our efforts to solve some of the most pressing issues facing the natural world.

View all issues