I have caught them in Washington, but it was incidental to steelhead and salmon fishing. Some of the lakes out there have them and when they spawn, which I believe is in the fall, they'll run up the tribs in decent numbers.
I don't know if you'll get any replies with an X marks the spot in Idaho or Oregon. I believe that if you do the research, find the streams that hold them, maybe look for ones that are out of the way and hard to get to, you'll find some fish.