Stayed here for a night of camping. I had high expectation given its remote location closer to a river but I was a bit disappointed. The campground entrance sign asks that everyone must register first even if they had reservation. There was no host at the office and it was had a sign that said "closed". We headed straight to our site but before setting up our tent, decided to head out for some boating. When we returned another party had started to set up tent at our site. I had to show them the reservation confirmation and they packed up and left. They couldn't find their site number and it appears that there was no one to help them.
As others have noted, this place has a lot of spiders so be aware because the spiders will be crawling all of the table as you eat. In addition to spiders there are lots of mosquitoes and tiny flies that are attracted to light. They flood your tent at dawn unless you keep it closed. This should not be an issue because camping is all about being in nature and with nature comes insects and spiders too. I'm just giving fair warning to people planning to camp here.
Lastly, we were anticipating but didn't really hear much of train noise as others mentioned. Our camp site was #30, closer to the lake so it's possible that we didn't hear the trains. Trains do pass by every hour or so. I think we also didn't hear the train because the party right next to us was blasting loud Spanish music well past 10 PM.
There is a trail going along the river but it’s really not interesting enough for hiking. The same goes for biking; there are far better places for boating, kayaking, hiking or biking than this area.
We don't plan to visit this campground again as it was definitely not worth the long drive from Seattle, given that there are so many camping options available that are far better.