You can drive right to the Barrier Dam. It's just passed the campground. You can stop at the campground store and ask directions...they're pretty nice there.

You drive into Salkum, follow the signs to the Cowlitz Salmon hatchery (not the trout hatchery...that's blue creek) and that's where Barrier is.

It will be Combat Fishing but if you can deal withthe crowds, that't the best place to hook fish.

Good Luck