EAGLE — Just before hundreds of young athletes descend on Eagle for the Colorado High School Mountain Bike League State Championships on Sunday, local riders have found a popular mountain bike trail sabotaged with spikes.

Riders this week found spiked boards buried on an unnamed section of trail near the Dirt Surfer trail above Eagle, prompting a multi-agency investigation involving the Bureau of Land Management, Eagle County Sheriff’s Office and the Eagle Police Department.

“We are definitely taking the threat of potential harm very seriously,” Eagle County Sheriff’s spokeswoman Amber Barrett said. “We don’t want anyone retaliating over this. We want everyone to get along on the trails. It’s hunting season and we’ve got trail joggers who have issues with mountain bikers who have issues with hunters and horseback riders. But setting a malicious trap like this, we are not going to take lightly.”

Every once in a while, local riders find branches dragged across trails, said Charlie Brown, whose Mountain Pedaler bike shop in Eagle has served as the town’s cycling hub since 1999.

“But I’ve never seen anything malicious like barbed wire or nails,” said Brown, who a month ago found logs and branches strewn across the Redneck Ridge trail above town.

In May, mountain bikers found spike-embedded bricks buried on the Little Scraggy Trail in the Buffalo Creek area of the Pike National Forest, prompting an investigation. It was the second time in as many years that the Forest Service investigated trail traps that could endanger bikers, hikers and horseback riders in the Pike National Forest.

These instances bubble up every so often. A biker in June 2014 discovered spiked boards buried in the Prince Creek trails outside Carbondale. A 64-year-old woman was convicted of criminal mischief in January after wildlife cameras caught her dragging tree limbs across popular trails in North Vancouver, British Columbia. A 57-year-old psychiatrist was sentenced to jail in 2013 for stringing ropes across popular bike trails. In 2011, a vocal critic of mountain bikers renowned for vitriolic diatribes was sentenced to jail for attacking cyclists near his Oakland home. Mike Vandeman, who continues to rail against mountain bikes in the woods, in an e-mail to The Denver Post last spring following articles on the Little Scraggy sabotage, asked: “Why are nails a safety hazard, but speeding mountain bikers are not a hazard?” and “What is good about trail building?” and “Why the shallow journalism?”

Cyclists hope these events are isolated instances involving crazy people but the increasing regularity is troubling. Especially when the booby traps emerge in the backyard.

“I’ve heard of reports from across the country, but never here in Eagle,” said Yuri Kostick, the former Eagle mayor who was instrumental in developing the town’s network of mountain bike trails that have established Eagle as one of the state’s hottest biking destinations.

Kostick said there wasn’t vehement opposition when Eagle began sculpting plans for a network of trails spinning out of town. They routed trails around environmentally sensitive areas. They worked to accommodate horseback riders.

“But we didn’t see any opposition to building or maintaining trails,” he said.

The Eagle County Cyclists and Friends Facebook page bristled with fiery comments after a local cyclist posted snapshots of booby traps on Dirt Surfer. Many commenters suggested hunters, who are gathering in the public lands surrounding Eagle, are behind the proliferation of deer and elk legs lined up along popular trails like Boneyard, Pool & Ice and Dirt Surfer.

Police went up to the area where Dirt Surfer, Boneyard and Redneck Ridge meet late Thursday and removed eight boards spiked with nails and several sections of trail laced with barbed wire, Barrett said.

“At this point it seems a pretty isolated case,” she said.

Anne Pence, who discovered the spiked boards on a trail near Dirt Surfer, brought police to the location of the boards. She said on Thursday they found evidence that the spikes were targeting mountain bikers.

“Found written in the dirt in big letters,” she said. “NO BIKES.”