Fluoride Action Network

Roughly 8,000 Sun Prairie residents informed of fluoride water quality violation

Sun Prairie Star | April 11, 2023 | By Chris Mertes
Posted on April 11th, 2023

Roughly 8,000 near west side Sun Prairie residents are reacting to a letter sent last week by Sun Prairie Utilities describing a Department of Natural Resources violation for fluoride in their drinking water.

The letter, entitled “Important information about your drinking water,” described a Tier 2 violation in which Sun Prairie Utilities exceeded the fluoride maximum contaminant level (MCL), which is a violation of state and federal drinking water standards.

Samples collection on Feb. 24 showed 13.23 milligrams per liter and on March 6 the sample showed .56 milligrams per liter. The MCL is 4 milligrams per liter, according to the letter.

“This is not an immediate risk,” the letter reads. “If it had been, you would have been notified immediately.”

The letter also pointed out that some people who drink water with fluoride levels in excess of the MCL over many years could get bone disease. And, fluoride in drinking water at half the MCL or more may cause mottling of children’s teeth, usually in children younger than 9 years of age.

Cause explained

Sun Prairie Utilities Manager Rick Wicklund and the letter both explained that the fluoride pump valve in a west side high-pressure zone well was identified from SPU’s daily inspection as damaged on Feb. 24, resulting in the excess fluoride being siphoned into the adjacent 500,000 gallon storage reservoir.

In collaboration with the DNR, the well and reservoir were isolated and taken offline. The reservoir was then flushed and fluoride levels dropped to normal levels of less than 2 milligrams per liter.

“Action was immediately taken upon discovery on February 24th. The DNR wrote the language in the paragraph that indicated two test results, the second of these measuring back to normal levels (.56 mg/L is in the range of a normal test) and was taken after the well and its adjacent reservoir was brought back online, in essence a verification that everything was good,” Wicklund explained in an email to the Sun Prairie Star.

“The Maximum Contaminant Level (MCL) is 4.0 mg/L for fluoride. Exceeding the MCL at the entry point of the well into the distribution system is what created the violation,” Wicklund added. “We isolated and flushed the well/reservoir until getting it to normal levels of below 2.0 mg/L on February 24th. At the same time, we were flushing five locations on the westside of Sun Prairie, until all locations on the distribution system also tested below 2.0 mg/L.”

Because SPU does daily well testing and inspection, Wicklund said, the fluoride chemical valve problem was one that was identified within a 24-hour period.

“The DNR was pleased with our quick response to alleviating the issue. The chemical feed pumps were plumbed to code, but we have now placed them above the chemical tank to prevent the possibility of future leaking into the reservoir should a chemical feed malfunction occur,” Wicklund explained.

“In addition, we are working with are SCADA provider to send an electronic alarm should an identification of chemical feed malfunction occur,” Wicklund said. “Overall, I think the water operations crew made a nice response to the issue. They notified and collaborated well with the WDNR from the time of identification until levels were returned to normal.”

The letter also states that for the entire week after the discovery, samples were taken to assure the distribution system continued to have normal levels. Samples taken at Broadway Drive, for example, never saw any elevation. Levels were also not believed to be elevated north of Windsor Street.

“As a water system operator,” the letter concludes, “Sun Prairie Utilities measures the chemical contents being distributed into the system daily and assures that the problem was expeditiously resolved.”


Some residents completely disagree with the letter’s assessment of the way the excess fluoride notification was handled.

“This happened in February and they are informing us in April?” one angry resident wrote in an email to the Sun Prairie Star.

“I received the letter yesterday in the mail and as I was reading the letter it was telling me that the fluoride in the water now is safe to drink,” Sun Prairie resident Tyrees Scott told WMTV NBC-15. “I didn’t even know it was a problem here. They didn’t let us know that it was a problem so now that I know that it’s drinkable.”

A Sun Prairie woman who received the letter but wanted to remain anonymous told NBC-15 that she wished SPU had a policy where they would notify the public immediately. She said her biggest concern is her children’s safety, being a mother of two young children and having a baby on the way.

“It does make me feel less safe going forward knowing that a contamination could happen again and we might not hear about it until later on,” she told NBC-15.

“When it comes to people’s health, it’s not SP Utilities’ decision to delay notification to over 8,000 homes, apartments, and business owners,” wrote Del Mineard Jr., a Weybridge resident who received the letter.

“A good utility company would have released one press release with the basic information, then followed up immediately with a mailing to the 8,000 addressees of the issue, followed by a second press release when the issue was resolved and then finally the letter, we received on April 5 summarizing the issue(s) and corrective actions,” Mineard added.

“That would be excellent communications to their customers and would showed they place a high level of transparency with their customers which would have given those people with unique medical issues the opportunity to switch to bottled water and talk to their doctors,” Mineard wrote in an email to the Sun Prairie Star (see Friday’s Letters to the Editor for Mineard’s letter).

SPU is assuring residents the water is safe to drink and no precautionary measures are needed, such as purchasing water from a different source.

Individual customers with concerns should contact SPU by phone at 608-837-5500.