Local, state and federal agencies shut down an illegal marijuana grow operation in Pike National Forest Thursday.

Agents uncovered the 18,300-plant operation on 5 acres off Rampart Range Road, almost 7 miles outside Woodland Park, according to the U.S. Forest Service, which manages the land.

About 2,000 pounds of infrastructure, including irrigation pipes, camping gear, tarps, trash, chemicals to deter wildlife, and multiple 50-pound bags of fertilizer had been installed, the Forest Service said.

No arrests have been made, the Forest Service said.

Details were sparse on how the grow operation was uncovered, and the Forest Service said the find is under investigation. But it drew the attention of numerous agencies, including the Colorado National Guard, Drug Enforcement Agency, Department of Homeland Security and Homeland Security Investigations.

The El Paso County Sheriff’s Office’s SWAT team also assisted in securing the property, spokeswoman Jackie Kirby said.

The production of marijuana and other illegal drugs on National Forest System lands is forbidden, but not uncommon. Under federal law, marijuana possession, use, or cultivation remains illegal on national forest lands.

In recent years, officials have discovered a slew of large-scale marijuana growing operations on national forest lands across the state.

The list of drug busts has included 4,400 plants in Pike National Forest in September 2010, 11,700 plants in the San Isabel National Forest in September 2015, 4,000 in Pike National Forest and 1,000 in Routt National Forest in August 2015, and 6,400 in San Isabel National Forest in November. Another 13,000 plants were discovered Aug. 4 in the San Isabel National Forest near Cuchara.

It can damage sensitive riparian areas, lead to environmental problems, and is harmful, sometimes fatal, to wildlife, the Forest Service said.

One outdoor marijuana plant can produce 1-2 pounds of marijuana product annually, according to the U.S. Drug Enforcement Administration’s Denver Division.

The Forest Service said charges against people connected to the growing operation may include the following federal offenses: conspiracy to distribute marijuana; depredation against property of the United States; cultivation on federal property; environmental damage from illegal manufacturing; and knowingly and intentionally manufacturing, distributing, dispensing, or possessing with intent to manufacture, distribute, or dispense a controlled substance.

The minimum sentence for trafficking 1,000 or more marijuana plants is 10 years for first-time offenders and 20 years for second offenses. Convicted individuals may be fined up to $10 million for a first offense and $20 million for a second offense, under federal drug trafficking penalties.