Catherine Creek State Park

We stayed here one night on our way to Wallowa Lake. This is a walk-in only campground with no hook ups. The sites are pretty much open with a couple tucked under some trees. Most of the sites are big enough to handle large rigs. The campground is right along the creek on one side and the highway on the other. Really, it's literally backed up to the road. Luckily, the road is not too too busy however it was busy enough to notice. There are bathrooms with flush toilets but no showers. A couple of nice trails to get out and take a walk.

We camped in mid-October and had the place to ourselves. We left the Interstate at La Grande which is the closest sizable town, 22 miles from the park.
The closer you get to the park, the curvier and hillier the road becomes. I think out phones lost signal about 4 miles from park.
Although no electric, we loved it there. Camphost was gone for the season, so paid for site and firewood by honor system.
We were going to stay another night, but rangers came to shut off water and lock restrooms the next morning.
There is a day use area a short distance away, with a trail from the the CG. Possibly busy in summertime....busy with free when we stayed.

Quiet, peaceful late September. I like smaller campgrounds if I can find them.
Faucet, fire pit & flush toilets.
Bonus.
Some road noise/traffic before bed & early rise. Otherwise you sleep to the river white noise.
No cell service