The plants were found at five sites on the east slope of Bolinas Ridge that borders Kent Lake, Lt. Barry Heying said.
The Marin Municipal Water District, National Park Service, California Department of Justice and U.S. Drug Enforcement Administration also participated in the eradication effort between 6 a.m. and 2 p.m.
The pot garden raiders also found living areas with lean-to tents, garbage and pesticides at the grow sites. No one was present in the camps and there were no arrests, Heying said.
The sheriff's office has been monitoring two-dozen known grow sites in the area since 2006, Heying said.
This year, rather than wait until the plants were grown, 12,900 immature plants without marijuana buds were cut so they could not be planted again, saving the cost and effort of hauling them out by helicopter, Heying said.
The growers seemed intent to keep the gardens small and spread out as more than one site was tended from one campsite, Heying said. There were also several small grows with only 10 plants, Heying said.
The illicit and clandestine marijuana gardens have typically been found in the Mt. Tamalpais Watershed, Heying said.
Heying said the growers have little regard for public safety or concern for ecological damages they create.
"These types of criminal enterprises result in erosion damage created by the clear-cutting of indigenous plants as well as hazardous trash left behind by the lawless operators," Heying said.
Dangerous chemicals used by the growers also seep into the watershed and create additional hazards, Heying said.
"Increasingly, citizens and visitors are becoming afraid to use public parks due to these individuals invading public lands," Heying said.
In 2009, the California Campaign Against Marijuana Planting seized 4.5 million marijuana plants in the state.
Mendocino, Lake and Sonoma counties are typically among the top 10 counties where the seizures occur. Marin County was not among the top 40 counties in 2009.
