They say pot growers are expanding their operations in state and national parks -- knowing budget cuts are leaving fewer people to track them.
Authorities announced the seizure last week of more than a billion dollars worth of marijuana in Sierra Nevada forests.
They arrested 82 people, all of them with links to a Mexican drug cartel.
Federal agents say California is the top spot for growing domestic pot in America. Most of it is hidden in state and national parks, and harvested by illegal immigrants smuggled in to do the job.