Habitat is more than just the freshwater stream. It is the whole watershed, top to bottom, ridge to ridge. It is the water, both surface and ground. It is the runoff. Then, habitat is the estuaries and following that the ocean. Habitat is also, as Jeff Cederholm said, the salmon.

Your little stream section may look pretty good, and may be in reasonable condition, but if there is no food in the ocean, if the estuary is converted to ports and marinas, then the fish still get screwed.

I believe that there is no one big magic silver bullet that, if implemented, fixes everything. Banning all fishing everywhere will still not restore the Columbia due to the dams. Taking every dam out of the Columbia will not restore it due to the fisheries and watershed development. But, since we can show how bad gill nets are or how bad dams are or how bad dairies are we can deflect blame from our favorite activity.