Dr. Lynn Silver Chalfin, Sonoma County's health officer for about a year and a half, announced her resignation this week in e-mails to co-workers and health care colleagues.
Silver Chalfin, 55, said Friday she was taking a public health job in the Bay Area but was not at liberty to disclose the position.
"I love the county. It's an amazing place," she said, adding that she hopes to collaborate with Sonoma County on health issues in the future.
Silver Chalfin's last day in the job that pays $202,555 a year will be Dec. 5.
Silver Chalfin said her departure has nothing to do with her strong advocacy for a controversial plan to put fluoride in most of the county's drinking water.
"I'm definitely not leaving because of fluoridation," she said, calling it "an absolutely correct and important public health policy."
Silver Chalfin, who previously served as assistant health commissioner in New York City, started work for the county part time in April 2012 and became the full-time health officer about four months later.
In New York, she pushed for a ban on artery-hardening trans fats in food establishments — the first such initiative in the nation — and a law requiring calorie labeling at fast-food restaurants.
Public health has been her life's work, including 15 years as a professor of public health in Brazil.
"She's highly skilled, has an amazing background," county spokesman Peter Rumble said. "It's a loss in the sense those skills aren't going to be here."