Heres what I think; Deschutes, Snake, Clearwater, Salmon rivers will see the majority of those fish. The Clearwater has the largest steelhead hatchery in the world. Someone may correct me on that...
Youve probably heard the terms A-run, and B-run, when people are talking about Steelhead. IMO, most of the fish crossing the Dam now are A-run fish, and are headed to the Snake, and Salmon rivers. These A-runs are mostly 1-2 salt fish, which means they spend 1 or 2 years in the ocean before turning tail and heading upriver. A-runs are generally 5-10lb fish.
B-runs are headed to the Clearwater, and a few other tribs. B-runs are 2-4 salt fish and weigh in between 10 and 20+lbs.
But what do I know....
Fishtopher, you nailed that one right on the head...........I used to fish the John Day River in hopes of catching a B run fish that made a wrong turn. Some of those Idaho bound B run fish make that mistake but not a lot.
The Grande Ronde and Wallowa rivers will get their share of those summers as well!