State Attorney General Jerry Brown says Mexican drug cartels are planting the massive pot farms in places like Yosemite National Park or forest service land. 

 “This is not a few guys growing a few plants.  This is massive criminal syndicates raping the lands of California.”

He says they use pesticides and redirect streams – hurting the environment.  And they’re armed – often with AK 47’s, says U.S. Attorney McGregor Scott.  He says they’re worried about backpackers running into a pot-growing operation:

“Unfortunately I think we may end up with a lethal encounter between a recreator – someone who’s out hiking, taking advantage of Yosemite national park and an armed drug dealer.”

A marijuana advocacy group criticizes the crackdown – saying it drives growers to use suburban pot houses instead.