More than 16,000 marijuana plants worth an estimated $48 million were destroyed as law-enforcement officers from nine agencies raided a marijuana farm in the Ross Lake National Recreation Area.

More than 16,000 marijuana plants worth an estimated $48 million were destroyed as law-enforcement officers from nine agencies raided a marijuana farm in the Ross Lake National Recreation Area of the northern Cascades on Thursday.

Lt. Rich Wiley, head of narcotics for the Washington State Patrol, said it was the first known marijuana grow operation found in a National Park Service site in Washington.

The farm was located by the pilot of a helicopter working on a maintenance project for the Park Service. Investigators said the appearance and techniques used at the site resemble those used by Mexican drug-trafficking organizations which have been cultivating marijuana in national parks in California.

In addition to the marijuana, agents removed more than 1,000 pounds of garbage, fertilizers, pesticides and herbicides, irrigation piping, and propane canisters.

Damage to the park done by the growers included cutting trees, terracing land, diverting creeks and installing irrigation systems, spreading chemical fertilizers, harassing and trapping wildlife, constructing living quarters and fences, and spreading garbage and human waste.

More than 50 officers were involved in the raid.