Yep thats what I have heard about the Salmon from my east coast friends. Thought it had changed though , but I guess not.
Better to go there after hunting season starts in October, crowds start to thin out then like out here in Michigan and Wisconsin country. Just make sure you wear some hunter orange though when walking the river because many of those guys that were snagging salmon in September are now carrying guns in October and November, hunting.
I bet December would be good up on the Salmon from what I have heard.
Salmon stop biting the closer they get to their spawning grounds. A much lesser percentage will bite then when they first enter the rivers. But some of them will. I have had dying ones bite a fly and others in great shape totally ignore it. Hard to figure out which ones will bite.