COLORADO Boulder, Colo., disc jockeys "Willie B" and "D Mack" were just looking for a good time when they invited KBPI listeners to join them with four-wheel drive vehicles at Caribou Flats, west of Boulder, on Sept. 23. But by the end of "Mudfest," their unofficial gathering, 200 off-road vehicles had driven through a 25-acre patch of alpine wetlands, wrecking eight acres of private land, rutting an acre of Arapaho-Roosevelt National Forest, and casting a long shadow over Colorado's growing off-road community.





"Unfortunately, it reflects poorly on everyone with a four-wheel drive vehicle," says Scott Reibel, president of the Colorado Association of Four-Wheel Drive Clubs.





While federal land managers admit that off-road vehicles are responsible for illegal damage on public lands every year, they say the majority of off-roaders respect rules and land.





But Roz McClellan, director of the Rocky Mountain Recreation Initiative, says Mudfest "is an example of similar incidents all over Colorado." To rein in four-wheelers, McClellan thinks money from off-road permits - which have increased fivefold in Colorado in the 1990s - should be used for heavier policing and trail closures.





Willie B and D Mack each received a $50 fine for their participation in "MudFest," and Boulder County authorities say other fines might be on the way, thanks to videotapes taken at the scene.