A recently established national monument in Southern California is being overrun—not by people, necessarily, but by feral cattle and pit bulls.

President Obama created the Sand to Snow National Monument outside of Palm Springs in February 2016. Since then, visitors have reported frightening encounters with unbranded cattle—including bulls weighing as much as a ton.

To make matters worse, a rogue pack of pit bulls has been roaming the monument’s slopes.

The Sand to Snow National Monument includes more than 150,000 acres of steep terrain near Palm Springs, Calif.

Officials with the Forest Service and the Bureau of Land Management, which jointly manage the 154,000-acre monument, plan to convene a team of land managers and wildlife biologists this month to devise a strategy for eradicating the animals.

The monument, which stretches from the desert floor to the top of 11,503-foot San Gorgonio Mountain, includes a 30-mile stretch of the Pacific Crest Trail. In the two years since it was established, annual visitation has jumped from about 90,000 to nearly 150,000, increasing the chances of conflict with the animals.

Land managers believe the cattle are descendants of herds that grazed throughout the region a century ago. The origin of the pack of pit bulls is unknown.

The feral cattle have carved new trails through the monument and consumed a variety of native vegetation crucial for the survival of native species, which include rare creatures such as arroyo toads, California desert tortoises and Nelson’s bighorn sheep.

The California Department of Fish and Wildlife tried last year to capture the feral dogs in traps, according to a report in the Los Angeles Times, but were unsuccessful.

Terry Anderson, a board member with the Society for the Conservation of Bighorn Sheep, told the newspaper that the feral cattle, believed to number about 150, are “ripping up this monument and scaring the heck out of folks who cross paths with them.”

He said he supports “lethal removal” of the animals, noting they can transmit disease to native bighorn sheep.