Sonoma County supervisors on Tuesday approved a trio of actions aimed at improving dental health in Sonoma County, including a contract to complete a study on fluoridation of the county’s drinking water.

The draft engineering study, which includes a cost analysis for adding fluoride to the county’s water system, was commissioned by supervisors in February 2013 for $103,000 but it has yet to be publicly released.

On Tuesday, the Board of Supervisors authorized paying an additional $10,000 to MWH Americas, a Colorado-based firm, to incorporate feedback from the county’s new public health officer and other officials into their analysis.

Before the vote, Supervisor Susan Gorin voiced some concern about allocating additional money to a study that she and her fellow supervisors have yet to see.

“This caught me a bit by surprise,” she said. “I have some serious concerns — this might be a bit premature because this board hasn’t made a final determination about where it’s going with fluoridation.”

Tuesday’s vote, originally slated for swift approval without public comment, was moved off the Board of Supervisors consent calendar to the regular calendar, offering the chance for a broader discussion.

Two people spoke in opposition, including Dawna Gallagher-Stroeh, an anti-fluoridation activist who is seeking to curtail the county’s push to fluoridate its drinking water, citing what she has characterized as faulty science and supposed health dangers.

But Supervisors Efren Carrillo, Shirlee Zane and David Rabbitt all said they were in favor of fluoridation, which medical experts insist is a safe and the most cost-effective way to prevent tooth decay. A county decision on the matter, expected this coming spring, would add fluoride to drinking water supplied by the county Water Agency to 600,000 people in Santa Rosa, Rohnert Park, Cotati, Petaluma, Windsor, Sonoma, Valley of the Moon and parts of Marin.

“I don’t want to give the impression of that we’re wavering in our support,” said Carrillo. “We’re just going to have to be creative with the funding.”

The board also accepted $162,475 in grant funding from the DentaQuest Foundation to increase access to dental care for county residents and allocated $145,000 to pay the California Dental Association Foundation to train county health care providers about the importance of fluoridation and prevention of dental disease.

The cost of adding the chemical compound to the county’s drinking water — estimated at between $459,000 and $587,000 per year — appears to be the primary barrier to supervisors’ approval of fluoridation.

“I still have questions about logistics of how we do this,” Rabbitt said. “Not about the science.”

Gorin said she has not yet decided whether to support fluoridation.

James Gore, who is replacing Mike McGuire as 4th District Sonoma County supervisor, has expressed skepticism about being able to pay for what he called the high cost of fluoridation. He also said he’s concerned about potential negative impact on the environment.

Zane said fluoride skeptics are misled. On Tuesday she held up a report from the American Dental Association highlighting 50 years of research documenting the benefits of fluoride.

“I’m happy to share this with you, Supervisor Gorin,” Zane said.