Sheriff's Sgt. Bill Gazza says the man, who has not been identified, was part of a four-member public works crew that was clearing brush on Monday morning. Gazza says he died at the scene.
County spokeswoman Dinah Phillips says the man had worked for the county since 1969 and that his co-workers are shaken by his death.
The county public works and sheriff departments and the California Division of Occupational Safety and Health are investigating.