Randy Waters can spot the telltale signs: foot paths eroded into steep gullies devoid of plants or trees.
"They're circumventing our barricades, and a lot of our roads are already chopped up," the U.S. Army Corps of Engineers ranger said.
Thurmond Lake's 70,000 acres of public lands are heavily used by hunters, hikers and campers. But off-road vehicles in unauthorized areas are beginning to take an environmental toll.
"We have one area near Plum Branch that was once a horseback riding trail," Ranger Waters said. "Now we have ATVs literally destroying the ground, running through creek beds. It's not even fit for horses now."
Public lands in Georgia and South Carolina are increasingly vulnerable to erosion caused by the use of four-wheelers, or all-terrain vehicles.
"People are concerned about them, obviously, because they like to be able to ride them," said Stephanie Neal, spokeswoman for the U.S. Forest Service, which manages Sumter National Forest near Augusta.
To accommodate growing demand for off-road vehicle trails, the Forest Service has begun designating special areas for riding four-wheelers, she said. But even the designated trails can be a problem.
"Last year, because of heavy rains, we did actually have to close our trails during the winter months," she said. Such a closure is under consideration again this year.
But illegal use of off-road vehicles is on the rise on federal lands, according to U.S. Forest Service figures.
This year, 829 citations were issued by federal rangers for offenses relating to off-road vehicle use in Sumter National Forest's Long Cane area, which includes 80,000 acres in Edgefield and McCormick counties alone.
In the entire 360,000-acre Sumter National Forest, more than 1,300 citations were issued this fiscal year, according to the Forest Service.
Most ticketing occurs for offenses such as riding in undesignated areas, riding on closed trails, riding off trails or resource damage. Penalties average about $100 per violation.
Ms. Neal said the majority of four-wheeler users are law-abiding. The increase in citations is due to the addition of law enforcement personnel and a dramatic jump in the popularity of the machines.
According to the National Survey on Recreation and the Environment, last conducted in 1997, about 14 percent of the nation's recreation-oriented population drive off-road vehicles or four-wheelers.
The previous survey, conducted in 1982, indicated 7 percent drove four-wheelers, meaning their use has at least doubled, Ms. Neal said.
"Our goal is to provide the opportunity to meet that demand, but at the same time we have to preserve our forest resources," she said.
Georgia's abundant wildlife management areas also are popular among four-wheeler owners.
"Sometimes they're a problem for us, but they're probably not a frequent problem," said Georgia Department of Natural Resources biologist Vic VanSant.
"Our rules are that they can be used wherever a road is open to any other kind of vehicle," he said. "Other than that they can't be used."
DNR has issued numerous citations for improper use of four-wheelers, but Mr. VanSant said the primary users of wildlife management areas -- the hunters -- are for the most part law-abiding.
"But we do have problems with folks who live close to public land, where youngsters take the machines through the woods and ride anywhere they please."
Most complaints about the machines come from hunters, he said.
"They (four-wheelers) irritate people who are legitimately using the forest, but they can also destroy vegetation when people continually ride them in one place."
Private property complaints about the machines are common as well.
"We get a lot of complaints about them, but we probably get just as many complaints about golf carts," said Lt. Steve Morris of the Columbia County Sheriff's office.
Georgia Power Co. rights of way, road shoulders and semirural subdivisions are the most common areas damaged.
"Some subdivisions have more problems than most," Lt. Morris said. In Columbia County, Haverhill off Harlem Grovetown Road and Sugar Creek near Interstate 20 have been particular problem areas, he said.
"We try to educate the driver, or more likely, the driver's parents, about where these machines are allowed," he said. "But the repeat offenders are ticketed."
Robert Pavey covers environmental issues for The Augusta Chronicle. He can be reached at 868-1222, Ext. 119, or firstname.lastname@example.org.