I fished that area some time back maybe 20 years ago and did good using wet flies. I think the river was the Grand Ronde.
Anyway there is lots of water in that area. Below is a couple of links that you might find useful:
1 WWW.Westfly.com. This site has a forum on Oregon and there was a post about that area recently.
2. http://www.dfw.state.or.us/ They have a weekly fishing report on Oregon fishing you might find useful.
Tim