The two-week operation to purge the Mendocino National Forest of illicit marijuana gardens uprooted 460,000 cannabis plants and led to more than 100 arrests, US lawyer Melinda Haag said.
About 680kg of processed marijuana, 27 guns and 11 vehicles were also seized.
The 364,225-hectare forest spans six counties in a region of mountains and forests known as the Emerald
Triangle for its high concentration of marijuana farms.
Agents raided more than 50 gardens teeming with rubbish, irrigation pipes and chemicals that damage
forestland and waterways, authorities said.
"The Mendocino National Forest is under attack by drug traffickers,'' Haag said.
The operation was part of an annual summer effort to eradicate marijuana from public lands across the state.
Six sheriff's departments, the state anti-drugs bureau and at least half-a-dozen federal agencies took part in the effort in the forest.
Spearheading the raids was Mendocino County Sheriff Tom Allman, who in his years on the job has had to balance county medical marijuana ordinances with state law and the complete federal ban on the drug.
Allman said none of the gardens raided showed any sign of being used to grow medical marijuana.
Environmental impact
Each summer for the past several years, authorities report seizing millions of cannabis plants from local, state and national parks, forests and other wilderness areas.
Public lands are often favoured by clandestine growers for their remote locations and rugged terrain.
In previous years, officials have blamed Mexican drug cartels for some of the state's largest growing operations.
Haag declined to comment on where those arrested in the current operation were from but said 25 are already facing federal charges.
This year's decision to focus on Mendocino National Forest stemmed from citizen complaints a year ago about an increasing number of confrontations with armed guards protecting areas where cannabis is grown, Allman said.
Forest Service officials and county leaders have also long complained about the environmental consequences of illegal marijuana farms on forest ecology.
California national guard troops, forest service workers and volunteers have removed 46,000 pounds of rubbish, 120 propane tanks, 116,000 feet of pipe, 13 manmade dams, 57 pounds of pesticide and tonnes of fertilizer from sites raided in the forest, Haag said.
