STAYTON, Ore. – As a heated battle rages in Portland over whether it should add fluoride to its water for the first time, the city of Salem has fluoridated its water since 1964.

And since 2001, it has used liquid fluorosilicic acid, which is the same chemical that Portland will use to fluoridate its water if voters approve the plan on May 21. Before that, Salem used sodium silicate fluoride.

Snowmelt from the Cascade Mountains transforms into the pristine waters of the North Santiam River, which is then used as drinking water for the city of Salem.

Nestled into the foothills of the mountains, and surrounded by numerous cottonwood trees, is the Geren Island Treatment Facility, which is about 20 miles southeast of Salem.

It is there the fluoride is added to the city’s drinking water at about 0.7 ppm (parts per million), the recommended amount by the U.S. Department of Health and Human Services for optimal fluoridation to prevent tooth decay.

• Watch a video of Geren’s fluoride treatment facility (The photo gallery also has more images of the facility and information.)

In a room at the facility, two 5,000-gallon tanks store the fluorosilicic acid.

From the tanks, the chemical is pumped out at about 4.5 gallons per hour and then mixed with the water diverted from the North Santiam River. There is an instrument attached to the south wall that continually monitors the flow.

Tim Sherman, the facility’s operations maintenance supervisor, says the chemical is 25 percent solution strength of fluorosilicic acid and the rest is water. It is trucked in from a distributor, Univar, based in Redmond, Wash. Sherman says the chemical is produced in Rock Springs, Wyo. by a company called Simplot.

At the concentration at which the chemical is stored in the tanks, it is toxic to the environment. For that reason, the room is self-contained. That ensures that if the tanks leak, the chemical drains through grating in the floor and is caught in a large sealed tank beneath.

Sherman describes fluorosilicic acid as a “co-product of the phosphate fertilizer industry (that’s) derived from a phosphate rock.”

And therein is one of the main controversies for many Portlanders opposed to adding fluoride to the city’s water, which is piped in from the pristine Bull Run Watershed east of the metropolitan area.

Clean Water Portland, the group opposed to fluoridation, is concerned not about fluoride itself but about the fluorosilicic acid.

“We have no issue with fluoride whatsoever,” says Clean Water Portland’s campaign manager, Kristen Robison, adding that they are OK with topical uses of it or with prescriptions. “Our concern with fluorosilicic acid and in addition to the fact it’s not a natural fluoride, and it’s not a natural mineral, it’s a byproduct of fertilizer production. It’s also frequently contaminated with arsenic, sometimes lead and sometimes mercury.”

Sherman acknowledges trace amounts of some of those contaminants are detected through tests of the fluorosilicic acid Salem uses. But he says the presence of those contaminates, like lead, are “very low concentrations.”

And when the fluorosilicic acid is mixed with the diverted river water for human consumption, “the dosage (of fluorosilicic acid) is a very low dosage,” he says, adding that from his knowledge about the chemical and from his experience, “it is safe.”

Still, for opponents like Robison, assertions such as that is no consolation.

“At a time when we know how many toxins are all around us – we’re trying to decrease the burden of toxic chemicals all around us, so it doesn’t make sense to purposefully add this chemical to the water.”

Proponents of fluoridation from the group Healthy Kids, Healthy Portland say that tests indicate there are no detectable increases in contaminants after the fluoride is added and dilutes in the water.

“Fluoride is a natural mineral that comes from rocks. Several products are produced during the same process including phosphoric acid, used to carbonate drinks. Fluoride added to water has been shown to be extremely pure,” says Mel Rader, co-Director of Upstream Public Health, through a statement released to KATU.com through Healthy Kids, Healthy Portland.

Rader is a fluoride advocate with a background in water engineering.

“Fluoridation has been thoroughly studied for over half a century. Thousands of credible studies, including a review by the CDC just last month, have confirmed that fluoridation is safe and effective,” he says. “Drinking water is frequently monitored and tested for contaminates, and those tests – including ones right here in Oregon – show no detectable difference between fluoridated and unfluoridated water.”

***On a visit last Friday to the Geren Island Treatment Facility, a rectangular black box hummed along inside the facility’s onsite lab with the same sound as a coffee maker. On that day it registered the amount of fluoride being injected into the water at about 0.61 ppm.

An alarm will trigger if the flow drops below 0.5 ppm and if it surpasses 1.0 ppm, Sherman says. But the alarm rarely fires, and when it does, it usually is when workers calibrate the instruments, he says.

Those instruments are calibrated about once a quarter, and the water is tested for fluoride levels in the lab daily by water treatment operators. It’s a human touch to constantly ensure the proper amount of fluoride is being added to the water.

All data from the monitors is recorded automatically by computer and test data is also recorded by hand in log books.

There is redundancy throughout the system, including backup pumps and monitors.

Since Portland’s $5 million proposed water fluoridation facility is still pending public approval, it’s difficult to know how a Portland fluoride treatment facility will parallel Salem’s. But Tim Hall, with the Portland Water Bureau, says it will be much bigger than Salem’s because of the need to fluoridate more water for more customers.

If Portland does approve fluoride, Hall says it will be a public process to pick a vendor to supply the fluorosilicic acid, which is the case with all city contracts.

“It would have to meet the needs of the plant that we would have to construct,” he says. “We’re planning a facility and we would have to make absolutely sure that the vendor we choose is able to provide the quantities and the amounts that are necessary to fluoridate the water.”

Small amounts of fluoride are already found naturally in Portland’s water but aren’t at the levels to prevent tooth decay. Hall says Portland would fluoridate the water to bump it up to the optimal level of 0.7 ppm if voters approve fluoridation.

If approved, Portland’s fluoridation facility will be built at the Lusted Hill facility in Gresham where there is already a facility that adds ammonia to the water to help keep the chlorine – which the city also adds to the water to disinfect it – from evaporating.

In addition to those two chemicals, sodium hydroxide is added to cut down on corrosion in the plumbing.

***Back at the Geren Water Treatment Facility, about 3,000 cfs (cubic feet per second) of water flows past its intake system. About 1 percent will be diverted for water treatment, which at the end of the day will amount to about 34 million gallons.

The facility spends about $120,000 to treat about 10 billion gallons of water a year with fluoride.