Growing up in Wisconsin the police would stop kids running stop signs, riding double, what have you, and make them attend a sort of traffic court/ sensitivity seminar for bikes. I don't know how it would affect public interest in trails, but being fined "man hours" (please forgive the sexist language) for damaging trails might empower people to be more sensitive to their impact on the world around them.
Side note: I went out hiking yesterday and the trails here where amazingly dry -- aside from a few heinous seeps we have.
(What are the best ways to facilatate seep drainage?)