Portland’s fluoridation debate has been overshadowed in recent months by other policy battles, from the Legislature’s struggle to control PERS costs to the city’s controversial adoption of a sick-leave mandate. That will change soon. The May 21 election is right around the corner and, as if to reintroduce the matter, the City Club of Portland released a committee report last week indicating that fluoridation is a pretty good idea.

Which, of course, it is.

City Club committees don’t always get it right on ballot measures. A panel considered Portland’s proposed arts tax last fall, for instance, and a slim majority of its members deemed the tax worthwhile. Support was nearly unanimous this time around, however, and panelists had the luxury of weighing numerous studies examining decades worth of data.

More than 70 percent of Americans served by public systems drink fluoridated water. The practice’s benefits are well-documented, and they’re particularly important to lower-income kids who might not have great dental care. Its risks are well-known as well. They’re minor relative to the benefits of fluoridation and consist primarily of fluorosis, a discoloration that doesn’t affect a tooth’s integrity.

It’s a wonder, really, that people are arguing about fluoridation at all. But argue Portlanders have, for decades. In fact, the most interesting component of the City Club report has nothing to do with the benefits or drawbacks of fluoridation itself. Rather, it’s a brief history of Portland’s fluoridation efforts, and it reveals just how persistently controversial the issue has been since the 1950s, when voters first weighed in. They said “no” at that point, but have said both “yes” and “no” since.

In 1978, for instance, voters supported a measure directing the city to fluoridate its water. Opponents responded immediately by producing their own ballot measure, and in 1980 voters said, “Nah, we didn’t mean it after all.”

The City Club’s history lesson isn’t merely interesting. It’s also predictive. Get ready for 1980 all over again.

Portlanders will vote in May on Measure 26-151, which would require the city to fluoridate its water. But the matter won’t end there, no matter which way the vote goes. Fluoridation opponents have begun gathering signatures for an amendment to the city charter that would appear on the May 20, 2014, primary ballot.

However, “the intention is to win this vote,” says Kristen Robison of opposition group Clean Water Portland.

Those who don’t like fluoridation are entitled to take their case to voters again and again, and they deserve credit for doing the necessary work. They’re on the wrong side of the issue, though. Barring the emergence of credible evidence that fluoridation’s drawbacks exceed its substantial benefits, Portland voters should support the practice as often as necessary.