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. Activities like channelization, dredging, and bank stabilization also harm salmon and steelhead because they alter streambeds and change flow patterns. Hydropower Dams can block adult salmon and steelhead migrating up river to spawn and juveniles migrating down river to rear in the ocean. Dams that do not allow fish passage have resulted in the extinction of some salmon and steelhead runs. Dams that provide some type of passage, such as fish ladders, improve the survival chances of migrating fish, but are still potentially harmful.