I submitted an update based on the website stated coordinates. Somehow the original coordinates in the dyrt put this campground just north of Leavenworth. The campground is actually about 1/2 way (as the crow flies) between Mt. St. Helens and Mt. Adams in the more southern part of western Washington.
The coordinates to google are 46.15664,-121.878452.
We really enjoyed our visit to this state park. We were centrally located to explore Whidbey island, see the tulips in La Connor, and even do a day trip to San Juan Island. The campground bathhouses were adequate, clean, and good hot water pressure. Per usual, the showers required tokens ($0.50 ea) for a 3 minute shower. Be sure hot is all the way on and cold off when you put the token in to ensure it gets hot fast! We camped in the Lower Loop, site 148, Apr 24 - May 2, 2021. It rained the first day, and never dried out by the motorhome. However, this site did have plenty of level area to accommodate our 32’ Class A easily, along with our tow dolly, and space for 2 cars in front of the RV on the slope down to the paved road.