For the first time Capitol Land Trust is employing Beaver Dam Analogue (BDA) technology for stream restoration on the Tilley East Preserve.
BDAs are constructed of wood poles, dirt, hay bales, rocks and small native trees. Wood fence posts are planted in two to three foot intervals in two lines that are ten feet apart. Small native trees are cut into ten to fifteen foot sections and woven through the posts. Dirt and rocks are piled along the post line and hay is spread among the poles to create filtered drainage. The hope is that the BDA will fill with sediment, riparian vegetation will establish and native beavers may move in and take over.
On the Tilley East Preserve, an old culvert with a one foot pipe has been pulled out and replaced by the BDA. The culvert has been blocking water flow and wildlife opportunities. The porous BDA allows water to flow through while also creating pools behind each one. This will preserve the water level in the adjacent wetlands creating wildlife habitat and helps to control drainage and damage to the downstream wetlands located on an adjacent property during flooding events.
Funding for this project has come from the Washington Coastal Restoration Initiative through the Recreation and Conservation Office.