Chehalis Basin Beaver Dam Analogs


Beaver Dam Analogs (BDAs) are simple artificial structures designed to mimic the form and function of natural beaver dams. Wetland filling and declines in beaver populations have reduced the number of slow water habitats important for natural flow regimes, salmon, and waterfowl. Installation of BDAs is intended to increase the quality and quantity of these important habitats to benefit streamflow and buffer native fishes and other aquatic species from the impacts of climate change.

A Beaver Intrinsic Potential model was developed to identify sites with the highest potential to sustain beaver damns and store surface water based on several geographic and hydrologic factors (including channel gradient, width and valley width). Once sites with a high likelihood of success were identified, the land owners were contacted. If the land owners expressed interest in having a BDA on their property the site was inspected for potential infrastructure challenges.

The BDA structures use untreated wood posts driven into the stream bed spanning the channel. Vegetation is woven between the posts to slow the flow of water. The structure will continue to collect more debris that are drifting downstream and will provide a jump start on a dam to beavers reintroduced to the area.

To evaluate the success of the BDAs, a reach was divided into thirds, the first was a control with no structures, the second had 6-12 BDAs, and the third was downstream of the BDAs and had no structures. In each of the three sections water temperature, hydrological changes, physical changes and biological changes were evaluated. Water temperature was collected continuously and other measurements were taken at intervals ranging from monthly to yearly and during various times of year to fully evaluate the changes to the ecosystem. It is expected that in the impact site, downstream of the BDAs, the water levels in the BDA pond and channel will increase, the large woody debris and fish presence will increase, and water temperature will decrease. All of which are considered improvements to the ecosystem.

This project is ongoing.

Start Date
Chehalis Basin
Project Type
Completion Date
Habitat Restoration

Goals & Objectives


  • To apply the Beaver Intrinsic Potential (BIP) Siting Model to identify suitable sites for BDAs with willing land owners.
  • Complete BDA designs and permits and evaluate the effectiveness of BDA techniques for future endeavors.
  • To see enhanced wetland habitat, increased diversity of aquatic habitat, and improved water quality and storage from the completed BDAs.
Primary Habitats Impacted By Project:
Managing Agency/ Organization:
Urban and Rural Riparian Stream Channels
Wild Fish Conservancy
Project Contact:
Budget or Project Cost:
Jamie Glasgow
Funding Sources:
Project Effectiveness Program of the Aquatic Species Restoration Plan and the Chehalis Basin ASPR
Washington Department of Fish and Wildlife