Salmon Falls has a fish ladder, so the steelhead and salmon can get past. According to the Regs, it open to fin-clipped steelhead all year. The Marion Forks Hatchery would probably have some info on the runs. I know coho have made their way up into the Little North Fork.
The ODFW is concerned about declining Chinook runs on the stream. I was told the Spring Chinook are holing up in deep pools all summer long but swimmers have been spooking them and the Chinook are having a hard time finding a safe spot to hole up. Makes sense.
the little north fork has never had a good run, its too low in the summer for steelies...in places its almost stagnent, and naitive nook numbers have never been very high. They will transplant "ripe" naitives in the upper end trying to get them to spawn and bring the return up but it just has never happened well there.