The California Highway Patrol arrested Tom Newell, 53, of Freestone after an off-duty firefighter saw him allegedly driving his 1998 Mercedes recklessly on westbound Bodega Highway around 3 p.m. Friday.
The firefighter was concerned the Mercedes was about to cause a collision, and he turned on his red emergency light to get the driver to pull over, according to the CHP.
The firefighter also flagged down a Sonoma County sheriff's deputy who was driving east on the highway. The deputy contacted Newell and suspected he was driving under the influence of drugs or alcohol, the CHP reported.
A CHP officer then determined Newell was driving under the influence of a drug and arrested him, according to the CHP.
A subsequent evaluation by a drug recognition evaluator confirmed the CHP officer's determination and Newell was booked into the Sonoma County jail on suspicion of DUI. He has since posted bail and been released.
Gino Giannavola, director of the Department of Health Services' Alcohol and Other Drug Services division said in an e-mail, "Mr. Newell is on leave and not at the worksite. It is a personnel matter and therefore no further comment at this time."
Newell also performs case management for treatment programs that serve drug users referred to them by the courts, according to the Web site.