It depends on what site you want to stay at. I believe you can stay for up to 7 days. You should be able to Google the park and find the prices. It is a beautiful place. Lots of hiking trails.
Not sure Contact the State of Washington about their prices on the web. Beautiful park, old large trees, shady most of the time, about 5 miles East of exit 68 on 5, 20 miles south of Chehalis, WA.
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