In the harbor area. You can see it far below you from 101 in the east side of the bridge over the Noyes River. The "office" is the cashier on the second floor of Silver's at The Wharf across the parking lot. It's also great place to return to for a sunset beer. Very user-friendly place. Upstairs rooms are $10 cheaper, but they were full.
Glad I stopped here, really nice campground at a cool place, behind a State of Oregon trout hatchery. The campground is pretty deluxe, there are heavy wooden fences lining the roadway and each campsite, I guess to clearly delimit where people should walk and where they shouldn't. So the forest ares are pretty pristine. The campground is either new or recently renovated. The hatchery has been around for a while.