I like what’s been happening at Mac. Run for developing builders and educating people about sustainable trails. Many of the volunteer builders are not mountain bikers, and have never built or maintained trail before. Having volunteers build trail gives more people a stake in the trail. Education about what it takes to build and maintain trail helps open eyes to the damage that can be done. If a trail is done right, it kind of looks like it’s been there forever, and the uneducated user may not appreciate what it took to build it, and not worry about damaging it.
Signage at the trail head might help a bit. Let people know some trail etiquette, and warn them not to ride or walk wet trail.