I both agree and disagree.

Habitat destruction, logging, loss of spawning gravel/siltation, etc., does impact anadromous fish poputations. However, I have not seen less available spawing habit (on rivers with striped watersheds) than than I've seen wild steelhead, i.e. there are still more gravel beds than there are steelhead to spawn on them. I'm not sure about the hydrology on the Cedar or Puyallup or other rivers you speak of, but I know the Forks rivers may actually be a stronghold for native steelhead because of the annual floods caused by logging. It's a catch 22 situation.