I'm unsure how you would enforce a fine (upfront deposit?). I would guess most would result in the offender being ejected and not welcome to return but as far as a fine I don't believe you would have the legal right to do so. I'm completely for the warning and ejection of the offenders. We don't own a dog but do realize there are wonderful owners and owners who are abismal. This summer we watched a young family next to us allow their terrier to off leash do running attacks at every leashed dog that walked by. Later I saw both the boy and girl (8 or 9) on top of the class c swinging toys on a rope. Dad was inside busy not caring. We were just floored.