A Deschutes County drug enforcement team raided and dismantled a 30-acre illegal marijuana grow operation in Alfalfa that detectives say was operated by a Mexican drug cartel. The team seized 9,227 plants and 2,800 pounds of processed marijuana in what is considered the largest drug bust in county history. Two pistols and an AR-15 rifle were also seized.

Detectives, along with the Deschutes County Sheriff’s Office SWAT team, arrived Thursday at the property at Dodds Road and Alfalfa Market Road. The officials detained and released about 21 people, mostly Mexican residents illegally trafficked into the United States to work in the illegal marijuana trade, said Deschutes County Sheriff’s Office Sgt. Kent Vander Kamp.

“We did not arrest any of the migrant workers,” Vander Kamp said. “Most of them were there to pay off debt for being smuggled into the country.”

The workers were found living in wooden structures and dome tents with limited clean water sources, Vander Kamp said.

“We didn’t know we would be walking into a humanitarian aid situation,” Vander Kamp said.

Several suspects in charge of the operation have been identified, but their names have not been released by the sheriff’s office. A Bend woman who oversaw the workers and the property was arrested and released with a citation to appear in court, Vander Kamp said. Other local people are suspects, and detectives expect to make more arrests.

Through the investigation, which began two years ago, detectives found the illegal operation diverted a significant amount of water from nearby homes and farms struggling with drought conditions.

The illegal site used underground water and maintained a complex watering system that supplied several 15,000- to 20,000-gallon tanks, Vander Kamp said.

“Because of the lack of resources and water, we weren’t expecting to see a grow that size,” Vander Kamp said.

In addition, the site used pesticides and insecticides that threaten residential water supplies, and used a large amount of electricity for lights and fans.