Leave it to beavers to help restore streams in the Black Hills

Beavers may not realize it, but they’re at the heart of a project in the Black Hills National Forest to restore areas adjacent to creeks. 

These spaces, called riparian zones, are crucial in maintaining water quality, preventing erosion, regulating water flow and providing habitat for aquatic and land animals. 

Black Hills National Forest officials say that beavers help keep riparian zones healthy, and their absence can contribute to problems including biodiversity loss and declines in water quality. 

To restore these riparian zones, Forest Service and Game, Fish and Parks workers are installing some human-made beaver dams, which the Forest Service calls “beaver dam analogs.”

The structures are constructed with logs, willow branches and chunks of sod – mimicking beaver dam-building.

Beaver dams slow down the flow of water and create small ponds or wetland areas upstream. This slowing of water velocity allows sediments to settle, leading to improved water quality. It also helps in groundwater recharge in the soils nearby, which benefits vegetation. And the wetlands provide habitat for a wide range of species, including fish, amphibians, reptiles and invertebrates.

Additionally, beaver dams trap organic matter and nutrients, such as leaves and woody debris, in the wetlands they create. This accumulation of organic material contributes to increased nutrient availability for plant growth. 

And the wetlands created by the dams store water during high-flow periods and gradually release it during drier periods. This process helps maintain soil moisture in a floodplain ecosystem.

While the beaver dam analogs serve as a crucial step toward restoring the riparian ecosystem, the ultimate goal is the return of beavers themselves. 

Some factors affecting Black Hills beavers’ natural habitats are development, deforestation, wildfires, trapping, pollution and the damming and channelization of creeks. And some landowners see beavers as pests, given they can cause flooding issues, block drainage systems and damage valuable timber.

Improved conditions in the targeted riparian areas could facilitate the natural recolonization of beavers; alternatively, reintroduction efforts could be conducted in collaboration with the South Dakota Department of Game, Fish and Parks. 

Recently, when GF&P found a beaver at its West River Outdoor Campus in Rapid City, the department decided the critter needed a better environment. Meanwhile, the Black Hills National Forest had already been working to restore an area in Schoolhouse Gulch with beaver dam analogs in the northwestern Black Hills, so the GF&P transported the beaver to the project area.