Curiousg

Just have a few questions for anyone familiar with the area. I'm looking at doing a weekend trip to Frenchman Coullee the weekend of May 30/31, and speaking to some guys I know in Seattle a few issues popped up that no one I know here could answer. Where's the best close by spot to camp? In the parking lot? Across the river in the state park? I don't need a full built campsite, but I don't want to run afoul of any unwritten rules for the area. What are some of the better books/sites with route info? This should be pretty easy to answer for anyone who has been there. When is rattlesnake season? I've heard this is something I should at least be AWARE of, so figured I would ask. Thanks.