Visitors examine dinosaur tracks at Red Fleet State Park east of Salt Lake City. (Utah Division of Parks and Recreation via AP)

Josh Hansen, a state park manager in Utah, heard two distant thunks hit the water as he docked his patrol boat.

He quickly found the source: About 500 yards away, someone was throwing pieces of stone over a cliff and into the reservoir. Hansen sped his boat to the opposite shoreline, just in time to find a boy holding two toe imprints from a partial dinosaur track.

"I saved that one," Hansen told The Salt Lake Tribune last week. "He had already thrown multiple [tracks in the water]."

Opened to the public as a state park in 1988, the nearly 2,000-acre Red Fleet State Park is known for the dinosaur footprints, traces of the towering carnivorous dinosaurs that roamed what is now northeastern Utah about 200 million years ago. But over the past six months, visitors at the park have been dislodging tracks imprinted in the dusty red sandstone and hurling them into the nearby reservoir, according to the Salt Lake Tribune.

Devan Chavez, spokesman for the Utah Division of State Parks, told The Washington Post in an email that his conservative estimate is that at least 10 of the larger, more visible footprints, which range from 3 to 17 inches, vanished in the past six months.

Before it transformed into a desert, the park was once a bog, with wet, muddy grounds that dinosaurs trudged through. Paleontologists think that the dilophosaurus, part of the raptor family, attacked other dinosaurs who were resting or drinking from the swamp, according to the Tribune.

In a post on the Utah State Parks Blog, Hansen said he found the problem alarming, and believes the people throwing the tracks into the reservoir don't realize that they could be destroying the millions of years of history that attracts visitors to the park from around the world.

“Some of the tracks are very distinct to the layperson,” Hansen said,”but just as many are not. That is why it is important to not disturb any rocks at the dinosaur trackway.”

He also said he believes that people aren't aware that dislodging the tracks is considered a crime.

“Disturbing them like this is an act of vandalism,” he said.

Under Utah Code, three-toed dinosaur footprints are treated as fossils, and those who try to destroy are subject to a felony charge. Charges haven't been filed recently, though. In 2001, three Boy Scouts were charged in juvenile court for engaging in the same problem Red Fleet State Park faces today: Tossing dinosaur footprints into its reservoir, the New York Times reported at the time.

Volunteer divers were able to recover about 90 percent of the dinosaur footprints they thought would be lost forever. Now, the park is discussing the possibility of sending a team of divers into the reservoir to do the same thing, Chavez said.

The park is also putting up signs asking visitors not to touch the stones.

"This has been an ongoing problem that we really would like to stop," Chavez told The Post. "These tracks are an important part of what makes Red Fleet State Park such a beautiful and special place. Being able to walk, hike, and even swim or boat next to where dinosaurs once stood is an amazing feeling."

Read more: 

Exotic pet trade linked to invasive fungus that’s killing frogs globally

Mother of cod: We’re fishing exactly the wrong fish, scientists warn