What do you do, those people seem to be everywhere and have little respect for anything!! My friend even had to stop someone using an Explorer SE who was digging HUGE holes and little care about it. Find out who the jerk is and turn his name in, make sure you let him know what happens when they do that and tell them you are going to turn in name and license plate to the Park. Most time they don't return and some even try to do better!! Sorry to hear you had to do that!!