Beautiful thing about the Eugene area is there is good steelhead fishing nearly all year. I used to try for salmon up the McKenzie at the Greenwood area and below leaburg, I also fished the Willamette below Dexter, but that place is nuts, and most of the guys up there aren't too friendly, I've been cussed out numerous times for being in some guys "spot", and then again just for not being a member of the male populous, with a reference that i didn't belong on the river, but instead in a kitchen. Needless to say, I gave up on that fishery. Besides, the salmon are few and far between. I know guys that catch salmon on both rivers, but they're hideous fish by the time they get this far upstream, don't know about you but I'm not down for eating dark fish, not even in the smoker, and I really think that they need to just be left alone to try and preserve what is left of that fishery.
Steelhead are another story completely, you can pull them out of the rivers here year round basically. Whether it be the Willamette/McKenzie (picks up in may-November) or the Siuslaw/lake creek (december to end of march) systems.
Also if you want to take a jaunt towards florence, just south of there is Siltcoos and Tahkenitch lakes, and they have semi healthy populations of wild coho from october-december, you can take 5 wild coho a year. If you don't have a boat though, you're restricted to the siltcoos river to the 101 bridge, however every fish that comes into that lake has to pass you, and I think the odds of hooking up are higher
Of thaey consider that sustainable. Should be some summers starting to show up in the next few weeks.