One of our favorite campgrounds. It's a bit far from the PDX area, but we've never had a problem getting an unreserved spot on a Thursday (it tends to fill up by Friday afternoon). The south Santiam river is the perfect solution of a hot Oregon summer day. Cold enough to really bring the temperature down, but not so cold that you can't stay in. There are at least four really good swimming holes (one with a nice rock to jump off).
The composting toilets are kept clean daily, but with Covid around, there is only a single visit by park staff per day, so toilet paper can run low by the end of the day (so bring your own). Lots of places to buy camp firewood from locals on Highway 20. The park staff typically also sell firewood when they drive through the camp, but that seems to have stopped due to Covid.
Sites along the river side of the loop are the best both because you're near the river (white noise) and far from highway 20 (which can be a bit loud at night monday-friday). There are no RV hookups, power, etc. Just two hand pump wells. There used to be a host, but that was discontinued about 5 or 6 years ago. Finally, you will most likely be well out of cell range here (yay!). For Verizon, you need to drive almost all the way to Foster Reservoir to get a good signal.