A “do not drink” order issued for the village of Williams Bay due to dangerous levels of nitrite in its drinking water supply has been lifted.
Residents in the small community near Lake Geneva in Walworth County had been urged to avoid their tap water since Aug. 27.
“After several days of diligent work, testing, and temporary mitigation efforts, the Wisconsin Department of Natural Resources has confirmed that water quality has returned to safe levels for all residents,” village president Adam Jaramillo wrote in a statement Sept. 5, lifting the order.
Exposure to high levels of nitrite can contribute to health problems in people of all ages, such as increasing risk for thyroid disease and colon cancer. But it is especially harmful to babies, who can develop methemoglobinemia — commonly known as blue baby syndrome — where deficient oxygen levels in the blood cause an infant’s skin to turn blue. If not spotted and treated appropriately, it can lead to death.
What tipped off authorities that there was a problem?
The timeline of the problem began on Aug. 20, when the county health department was informed two Williams Bay children had received a diagnosis of methemoglobinemia. Those children had been taken to the hospital, Sarah Yang, a toxicologist and hazard assessment section manager for the state health department, told residents during a Sept. 2 village board meeting.
After tests showed nitrite levels in their home’s water more than twice the safe level of 1 mg/L, the DNR expressed concern that it could be a system-wide problem, said Steve Elmore, program director of the DNR’s Bureau of Drinking Water and Groundwater. On Aug. 26, samples were taken from six locations in the village and sent to a certified lab.
When those samples returned Aug. 27 showing elevated nitrite throughout the water supply, the DNR issued the “do not drink” order and the village board unanimously authorized $100,000 to provide bottled drinking water for all residents.
Little has been shared about the children who became ill. Walworth County Health Officer Erica Bergstrom declined to describe their symptoms. A spokesperson for the Wisconsin Department of Health Services said the cases are part of an ongoing investigation and as such, the agency could not share more.
The village was about two months away from starting a new treatment to tackle elevated ammonia in its water supply, which can result in high nitrite levels. After the DNR alerted village officials to ammonia trending upward in 2021, they secured permits and funding for a treatment that would automatically add chlorine gas into the system to keep ammonia levels down.
How did nitrite get into the village of Williams Bay’s water?
Ammonia, which is typically produced by the decay of plant and animal matter, naturally occurs in the area’s groundwater, Elmore said. Bacteria that live on the insides of pipes in a water system convert that ammonia to nitrite in a process called nitrification.
These bacteria build up over time, growing faster in warmer weather and in areas of the water system’s underground pipe network where water doesn’t move around much, such as a dead-end street, Elmore said. The home where the two children became ill was on a dead-end street, he said.
If iron is present in the water, the process goes a step further to convert the nitrite into nitrate, which still carries health risks but is safe in higher amounts than nitrite. That didn’t happen in Williams Bay.
“That’s the worst part of it,” Elmore said. “That’s the chemical in all this … that is the most problematic.”
How did the water become safe to drink again?
Chlorine is the main defense against bacteria growth that could result in elevated nitrite levels.
Williams Bay adds chlorine to its water and flushes its lines twice a year, once in the spring and once in the fall, officials told residents during the Sept. 2 meeting. Immediately after the illnesses were reported, village staff flushed the line by the home, Elmore said.
In the past week, water lines throughout the village were strategically flushed to sweep away bacteria and circulate extra chlorine added to the system, said Lt. William Kostock of the Williams Bay Police Department.
On Sept. 3, water samples were collected at nine locations across the village and all showed nitrite levels had returned to below 1 mg/L. The DNR and state health department ordered a second round of testing to confirm, which came back Sept. 5 showing the same results.
At that point, the “do not drink” order could be lifted.
What happens next?
The village will re-sample areas throughout the water system for nitrite in 10 days, according to its “Water Plan Forward” document. That will ensure levels are still in the safe range. The automatic chlorination treatment will begin in November.
Elmore said the DNR can do more moving forward to assist municipalities with elevated ammonia in their groundwater to prevent this from happening elsewhere.
Because ammonia is not regulated under the Safe Drinking Water Act, which sets standards for drinking water in the U.S., there isn’t a clear picture of which communities across Wisconsin have high levels of naturally occurring ammonia, Elmore said. However, communities near Williams Bay, like Delavan and Elkhorn, have it too.
He said he’d like to better understand where those places are, as well as help municipalities with higher ammonia levels to tailor their water line flushing to keep the nitrification process at bay.
Madeline Heim covers health and the environment for the Milwaukee Journal Sentinel. Contact her at 920-996-7266 or mheim@gannett.com.
This article originally appeared on Milwaukee Journal Sentinel: DNR lifts ‘do not drink’ order for Williams Bay water after nitrite scare. What happened?
Reporting by Madeline Heim, Milwaukee Journal Sentinel / Milwaukee Journal Sentinel
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