I think it's more accurate to say that all communities must contribute, but each in their own way. That's because the nature of the problem is not the same everywhere. For example, in some areas of Eastern Washington, the focus is on making sure the streams don't run dry while other areas need to focus on preventing erosion, or keeping manure and chemicals out of the river, or growing shady trees along the river bank, or transporting salmon more effectively around dams. Well, this is absolutely true. Without trees to provide shade along the waters where salmon live and travel, water temperatures are too warm many months of the year for salmon to survive.
Trees also are key to an adequate food source for fish.
Trees and other vegetation also help stabilize stream banks to prevent erosion. For spawning salmon, this is crucial. Eroding banks dump soil into streams, smothering spawning habitat. It adds to flooding problems. And it dumps silt into rivers that have to be dredged for shipping.