(Dayton, OR) -- The Yamhill County Sheriff's Office has shut down the largest illegal marijuana growing operation ever found in the county. It was happened on two rural properties near Dayton. There were 99 greenhouses used to grow the pot. Police destroyed over 22-thousand plants and 10-thousand pounds of dried marijuana. 12 people were arrested. Yamhill County Code Enforcement is investigating solid waste concerns, electrical code violations, and illegal use of water from a nearby creek. 13 other police agencies and the Oregon National Guard helped secure the property while the search was underway.