If your talking about the one in Montesano, here is the info from their website (I googled it for you)
Camping is allowed from mid-March through mid-November and one may picnic any time of the year.
FEES: ARE AS FOLLOWS:
- TRAILERS AND/OR RV’S $25.00; Seniors OR disabled $22.00 per night
- TENT FEES: $15.00 per night
- PICNIC SHELTER EVENT FEES: $50 PER DAY OR $10.00 PER HOUR
RESERVATIONS ARE SUGGESTED, ESPECIALLY FOR HOLIDAY WEEKENDS AND MAY BE MADE BY CALLING 360-249-5117.