Maybe contact the City of Longview? If needed for a special event, maybe just call and ask if they have any ways of giving special permission for use. All I can think of for now. Good luck.
I would call Cowlitz County and speak to their Parks division for information on the lake and park. If they are not responsible entity, they surely can tell you where it is.
It most likely will be open because it has said it would be closed in the past & well it wasn't
Most likely will be open however, I would inquire with the city of Longview to ensure and also if you're looking for a special event.
Call the parks department
Call City of Longview
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