...been going every year for about 20 years for coho in Sept. Good stuff. The Situk and other area rivers, streams, lagoons and roadside ditches full of fish. The coho run gets top billing and for good reason. There are also all other species available too. Best part is that it is remote even for Alaskans...but luckily a 737 gets you there direct. Great salt action too for Kings in May-Jul and monster Halibut May-Sept. This action is only 5 miles off the end of the dock. Beautiful scenery.
The Situk was dying as a steelhead river until they imposed C&R a few years back (think you can keep one trophy fish). I think the Situk is now regarded as the best steelhead river in AK since the run has rebounded in a big way and they say 20 fish days are not uncommon. The Situk is a beautiful river and some say it is the perfect salmon/trout/steelhead environment (lake headwater controls the flow, lots of cover for the fish, river bottom of marl which looks like it was screened!).
I have never done steelhead, but sure would like to. Season peaks Apr-May. The drift is about 14 mi. from the put-in to the ocean. No whitewater to speak of, just river obstructions that sometimes require a chain saw or portaging. The steelhead are supposed to be big and feisty, they say plan on losing lots of gear! Weather is wildly unpredictable that time of year!