The eradication of the illegal pot-growing sites began at 7 a.m., Barry said. The sheriff's office did not immediately release details on the operation.
Barry said the sheriff's office had noticed an alarming trend of law enforcement officers and private citizens coming into contact with armed individuals at the grow sites.
Five such encounters have occurred at marijuana gardens in the Bay Area and counties further north in recent months, Barry said.
During a raid on June 29, Napa County authorities shot and killed a Fresno man who was guarding a marijuana grow near Lake Berryessa.
"More and more citizens and visitors are becoming afraid to use public parks due to these armed individuals invading public lands," Barry said.
She said today's operation is a step toward eliminating that threat.