SONOMA COUNTY (CBS SF) — Law enforcement agents for California State Parks uncovered multiple illegal pot grows at Robert Louis Stevenson and Sugarloaf Ridge state parks over the summer, leading to the arrest of three Santa Rosa men.

Park officials said the three men, who were not identified, were charged with illegal cannabis cultivation, carrying a loaded firearm in public, possession of an assault weapon, unlawful water diversion and polluting a state waterway.

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What State Park Peace Officers discovered in state parks over summer (California State Parks)

During one operation targeting a pot grow — a collaboration with the California Department of Fish and Wildlife — agents seized four guns, and discovered illegal pesticides were being used. Also, a water diversion was polluting a nearby waterway. Park employees returned to the site, tore up the grow system and eradicated all the remaining marijuana plants.

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For the past 150 years, State Park Peace Officers (SPPOs) have policed state parks, which are quite large: Robert Louis Stevenson State Park is 5,200 acres, while Sugarloaf Ridge State Park has 21 miles of hiking trails.

Park officials did not reveal when the SPPOs discovered the three illegal pot grows as of press time.

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Several massive illegal marijuana grows have been discovered in Sonoma County over the years. Most notably, county officials shut down two illegal grows last September that housed over 63,000 plants, making it the llargest illegal grow found in the area.