About 8,100 marijuana plants with a street value of about $28.4 million were seized in the coastal mountains of San Mateo County from late August to early this month, according to officials.
But authorities hauled away far more than just plants.
About 4 tons of garbage — some of which authorities described as potentially toxic to the environment — also were removed from the grow sites during the annual operation, officials added.
A 12-gauge shotgun and ammunition were found as well.
The grow operations were reportedly hidden in secluded areas and were equipped with sophisticated irrigation systems.
None of the weed farms’ operators had been located as of Tuesday, Sheriff’s Office officials said.