There are tons of resident cutts in there, all in the 5 - 12 inch range. It's probably a little early for searuns but there might be a couple there as well. I like fishing the upper river around Klootchy Creek County Park, which is less than a 10 minute drive from downtown Seaside. There's great fly water upriver and downriver from the one lane bridge. I'll be fishing that river Saturday morning, maybe I'll see you out there.
These 2 patterns have killed it on that river for me. The one on top is called a Muddler Minnow (I think) and I don't know what the one on the bottom is called but Don at River City Fly ties them and should have a few on hand if you have a chance to make it over there.