The best fishing will be in the reservoirs, Trillium, Clear lake, Harriet, Timothy, Promontory/North Fork, Faraday and a hand full of high mountain lakes in the Rock Lakes area. I've tried catching trout in the Clackamas, Sandy and Willamette but never had as much luck as in the reservoirs, I know people do catch trout and other species in the rivers though, you just have to know where to go and what to cast. Earler this year people were posting photos of nice trout taken from the Mollala river, but I never did any research to find out where the holes are on the Mollala that were producing.