Portland Watersheds Salmon and steelhead are very sensitive to changes in the stream environment. Any human activity that degrades water quality, instream and riparian habitat, or affects natural patterns of flow in rivers and streams is a potential threat to salmon and steelhead. Habitat Streamside vegetation is extremely important to salmon and steelhead.
Trees shade and cool the water.
Branches fall into the stream to provide the woody debris that is such an important part of salmon and steelhead habitat. Streamside vegetation also provides habitat for the insects that are an important food source for salmon and steelhead. Human development in stream corridors often removes the riparian vegetation so important to steelhead and salmon. Development can also cause erosion, which dumps sediment into streams. Sediment covers the gravel required for spawning and rearing, and can harm the aquatic insects salmon and steelhead eat.