Then rocks, logs and root wads were installed at the water line to slow the velocity along the bank. Slower water velocity reduces channel and bank erosion and siltation, enhancing the quality of salmon spawning areas. After the water line was stabilized, the remaining bank was restored. Previously excavated soil was wrapped in erosion-control fabric and then layered with willow cuttings up the sides of the stream bank. As the willows have become established, they have provided shade that cools stream temperatures.
Insects falling from the willows also provide a food source for salmon.
Another feature of the project was the construction of a culvert on Cottage Lake Creek, a tributary to Bear Creek. The culvert was built to provide fish passage, and habitat features around the culvert were designed to further enhance salmon habitat. This restoration helped to offset impacts from the proposed project. A major challenge facing our firm in the design of the wetland mitigation plan was taking a degraded industrial area and restoring it to a condition that would benefit wildlife, including salmon. In the restoration process, a channel was constructed to connect the wetland to the Duwamish River.