how much for a small scout troop and where do we make reservations?

I'm not sure about groups but it's a municipal park so you'll need to call the City during office hours.

It was $20 a night when we went two months ago. First come, first served, but it filled up quickly.

There is some information online is you search for it. I think it might be first come, first served and $20 or so for a night