PS,
I agree with your last point, but I don't believe that economic interests will ever be willing to sacrifice profits for habitat. They must be made to. That's why it was sad to see Measure 7 pass in Oregon. If this thing holds up to court challenges it will pretty much negate what regulatory progress has been made in streamside protection.
Obsessed, there is currently a large body of evidence suggesting that decaying fish, and the nutrients that are released during decay, are hugely important in stream ecosystem function in these latitudes. Regular nutrient inputs are perhaps more critical in streams than in lakes, because, as you said, stream water flows and nutrients exit the systems relatively quickly. They may not be as fully exploited as they would be in lakes but the temporary nature of nutrient availability in streams makes regular inputs absolutely necessary.