Beaver Campground is a great base for Washington gorge hikes deeper into the Gifford-Pinochet near Carson - including Falls Creek Falls (one of the prettiest waterfalls in the whole gorge area). If you're based in Portland and doing a weekend of hiking this is a good and easy base to keep you from having to make the 1.5 hour drive home and back to sleep. It's super accessible to get to after work for an evening camp and early start the next day.
There are a variety of sites available including group sites, single sites, double sites and 2 fully accessible sites. The campground takes reservations and also has walk ups. I was there in early June just after Memorial Day and the place was empty.
All sites have fire rings and picnic tables. Double sites have 2 tables. There is a limit to one car per single site, or you'll be charged an additional 10$ fee.
There are no showers, but it's pretty darn close to the baths at Carson Hot Spring Resort which feel nice after a long hike!