There’s nothing Brad Smith enjoys more than a tranquil walk through the protected wilderness in Central Idaho.

“It’s pretty amazing,” said Smith, as he looked out over the Sawtooth Mountain Range from the Salmon Challis National Forest outside Stanley, Idaho. “This is why people live here.”

“It’s something I’ve been doing my entire life,” he said.

But just as Smith is waxing poetically about Idaho serenity, a motor bike unexpectedly interrupts the tranquility with a growing roar.

“When I grew up in Idaho we had less than 20,000 [off-road] vehicles,” he said after the noise died down. “Now we have more than 140,000.”

Smith, who works for the Idaho Conservation League, says off-road vehicles like motor bikes are tearing up the landscape of the Salmon Challis, the nation’s largest public park south of Alaska.

“If the trails aren't in the right location,” he said, “[they] can damage the water. [They] can damage the wildlife habitat.”

It’s a situation Smith believes demands federal action. “We need to manage their use,” he said. “Just like we manage hunting and fishing.”

Smith's organization, the Idaho Conservation League, is now suing the United States Forest Service for “mismanaging” the use of off-road vehicles inside the Salmon Challis.

“We want a better plan,” said Rick Johnson, ICL’s executive director. “The current one isn’t working.”

It’s a lawsuit that has Brian Hawthorne, executive director Blue Ribbon Coalition,  fearing for the future. His group lobbies for the rights of off-road vehicles.

“The fear is a death of a thousand cuts,” said Hawthorne. “Each year more and more lands become off-limits to motorized vehicles.”

He says he’s also lobbying for the rights of hikers like Smith, as well.

“As soon as they ban us, they’re going to be coming after them,” he said. “The first step is motorized users,” he explained. “Then they go after mountain bikes.”

Hawthorne says “some radical environmentalists” promote what he calls “human exclusion zones.” “Our fear,” he says, “is that they'll reach their goal.”

Johnson calls that fear “ridiculous,” saying the lawsuit is simply trying to preserve what’s there for future generations.

“We’re trying to protect a natural resource and a quiet recreation experience.”

Douglas Kennedy currently serves as a correspondent for FOX News Channel (FNC). He joined the network in 1996 and is based in New York.