The sites containing a total of 5,070 marijuana plants growing in various stages were found in secluded areas in the San Francisco watershed and Skyline Ridge Open Space area, officials said.
Suspects maintaining the grows were not found, but at the sites officials found what they called sophisticated irrigation systems and campsites. At two of the grow sites officials found sleeping bags, hammocks and food. At another area a loaded .22 caliber rifle was found, officials said.
The annual operation was a multi-agency effort that included the California Department of Justice, San Mateo County Sheriff's Office and San Francisco Water Department.