BATTLE LINES in the fight to treat Portland's much-lauded municipal water supply with fluorideā€”a controversial idea pushed secretly in city hall over the past several monthsā€”fell into sharp focus this week.

After Commissioner Randy Leonard secured crucial support from two of his colleagues, Commissioner Nick Fish and Mayor Sam Adams, he served notice on Tuesday, August 21, that the city council would move forward with fluoride next month. A hearing is now planned for Thursday, September 6, with a vote the following Wednesday.

"It is one of the most positive things I have ever done in office," Leonard said to the Mercury, calling fluoridation of water an essential antidote to the high rates of tooth decay facing Oregon children, especially in poor and minority families. "I will have done nothing I am more proud of."

But at the same time as Leonard was talking, emails, calls, and petitions by the hundreds kept pouring into city hall offices, urging the council to say no. And down in the city hall plaza on Tuesday, several dozen opponents of fluoride had gathered for an impromptu rally, clutching signs expressing their anger.

Some were moms. Some were clean-water advocates. Others came from Occupy Portland, whose social media pages have emerged as a potent hotbed of outrage over the fluoride push. Together, they stood as a clear warning that this fluoride proposal, like three others in Portland's history, will likely end up on the ballot.

And given that voters have said no three times before, that makes it anyone's guess if we'll actually have fluoride in our water or not.

"Some of these groups have been fighting fluoride for decades. We're all interested in the same thing," said Angel Lambart, a concerned mom who described fluoride as a "toxic" industrial byproduct.

Lambart, like others at the rally, was actively soliciting volunteers willing to help with a ballot push. Once the council approves fluoridation, opponents will have 30 days to gather nearly 20,000 signatures in a bid to ask voters to overturn it.

But is fluoride really that dangerousā€”or is it that opponents are preternaturally uncomfortable with the idea of putting things in the water?

It's well established that getting too much fluoride, in concentrations above what Portland would be adding to its water, can be harmful: weakening teeth instead of fortifying them against cavities. But fluoride foes also point to more dramatic negative studiesā€”some that purportedly link fluoride with reduced IQs (although those are disputed by nonpartisan scientists and fluoride supporters).

"We're all terrified. It's toxic waste," said Neriman Sagar, who stopped by the rally on her lunch break.

Portland is the largest American city yet to embrace fluoridationā€”Leonard made sure to point out that the federal Centers for Disease Control and Prevention ranks fluoridation among the 20th century's 10 best public health developments.

The current push is backed by a broad range of health care nonprofits and advocates who first approached Leonard for help close to a year ago. Leonard said he told them he'd take it on only if they did all the political workā€”pressuring city commissioners and hiring consultant Mark Wiener to help with messaging. But, said Leonard, "They actually did all the things I asked them to do."

As of press time, the only major Portland politico who hasn't signaled his feelings on fluoride was Dan Saltzman. Commissioner Amanda Fritz, while still undecided on whether to fluoridate, has said she supports leaving the decision not up to council, but to voters.

That puts her at odds with her opponent in her hard-fought reelection race, State Representative Mary Nolan. Nolan joins every other aspiring political candidate in this year's city racesā€”Charlie Hales, Jefferson Smith, and Steve Novickā€”in supporting fluoridation. Fritz's stance also echoes fluoride foes who wonder why the city is forcing fluoride on them when they can get it through so many other sources: toothpaste, tablets, and mouthwash, for example.

Leonard scoffed at the notion of a public voteā€”equating fluoridation with schools' requirement for immunizations and the city's decision, years ago, to add germ-killing chlorine to water.

"We didn't have the public vote on that," he says. "And we don't give out little chlorine tablets, either."