The U.S. Forest Service has closed an ATV trail system in Botetourt County, where erosion caused by four-wheeling has created high levels of sediment in nearby streams.

After completing water-quality monitoring, the Forest Service decided to close indefinitely the Patterson Mountain ATV Trail System, a 16-mile network that consists of a main route and 10 side trails.

"There are a lot of issues with this system," District Ranger Cindy Schiffer said.

Built in the early 1990s, the network has some trails that are too close to streams. Regular use by all-terrain vehicles has reduced some the trails to shallow trenches, routing dirt and mud into the waterways during times of heavy rain and snow.

After learning that the Forest Service had not tested the streams in recent years, Schiffer ordered monitoring that found trail conditions did not comply with the Jefferson National Forest plan.

The network will remain closed while the Forest Service develops a plan for its future, which will not be completed until at least this summer, Schiffer said.

Located in a remote section of northwestern Botetourt County that is accessible only by Forest Service roads, the Patterson Mountain ATV trail system is one of four such attractions in the George Washington & Jefferson National Forests.

When the trail was first proposed, environmentalists complained about noisy and polluting ATVs in the national forests, while hunters worried they would scare off the wildlife.

As a compromise, the forest service decided to close the trails annually from Oct. 1 through Dec. 8 and from March 15 through June 15.

Under Virginia law, ATVs are not allowed on public roads, which include Forest Service roads.

In recent years, the Forest Service has seen an increasing problem with rogue four-wheelers who like to veer off the roads to spin their tires in mud holes and creek beds.

For the most part, damage by these "mud boggers" has been caused by jacked-up pickup trucks and SUVs, Schiffer said. While there have been some problems with off-trail ATV use, the lighter vehicles don't cause as much environmental harm.

But even in designated areas, the impact is being noticed.

Recent tests "indicated a high level of sediment loading in a tributary of Patterson Creek that bisects the ATV area," Schiffer said. "Based on that, we took a detailed look at each of the drainage structures on the ATV system and found that most were not adequately functioning."

The closing is not expected to have an immediate impact on ATV enthusiasts, who usually frequent the trails during warmer weather. And even on summer weekends, the Forest Service counted few more than a dozen users.

As for the mud boggers, Schiffer said beefed-up law enforcement -- more than 40 people were charged last year with damaging federal resources -- and publicity about the issue seem to have reduced the practice.

After the Forest Service repaired the damaged areas, it heard from more than 100 people who appreciated the improvements, Schiffer said. With the appreciation came a lower tolerance for mud bogging.

"People are not as willing to turn a blind eye to it," Schiffer said.