Results from water tests at all Iredell-Statesville Schools earlier this month found high levels of an unregulated contaminant in Lake Norman High School’s drinking water, although officials say the test may have been flawed.
According to an ISS press release, water tests showed LNHS had higher levels of perchlorate than neighboring schools.
According to the water test report, LNHS water had 137 micrograms of perchlorate per liter of water. It was one of three schools to have perchlorate in the water. Shepherd Elementary School had 2.5 micrograms. Coddle Creek Elementary School had 1.8.
According to EPA documents, high doses of perchlorate can disrupt thyroid function. The EPA has a screening level of 14 micrograms per liter for perchlorate in tap water. Several states have their own screening levels ranging from 0.8 to 71 micrograms.
North Carolina does not regulate perchlorate.
The ISS Board of Education voted Monday to provide bottled water to students at LNHS.
ISS superintendent Brady Johnson said the school district had been considering a water test since the summer after another school district found lead in their water.
“We wanted to be proactive, so we weren’t caught in the same situation,” Johnson said.
Johnson said all but two schools in ISS are on municipal water, so he was not expecting any negative results. LNHS uses municipal water.
More confusing, the water line serving LNHS supplies water to six other schools, Johnson said.
“We speculate a skewed test or a human error,” Johnson added.
Reliant Environmental retested the high school’s water Tuesday and will do so again Wednesday. Those results are not yet available.
According to N.C. Department of Environmental Quality records, earlier this year the heavy rains of Hurricane Florence exposed coal ash at a site adjacent to LNHS. On Sept. 6, coal ash was exposed again by grading construction.
Following those reports, ISS said it would immediately begin testing the water at all of its schools in the county.
The LNHS test results do not show where the contamination may have come from, and it’s unknown if the nearby coal ash is a factor. It isn’t clear if coal ash contains perchlorate.
Johnson said there are three ongoing health-related concerns the public may have in the Mooresville area: a possible cluster of thyroid cancer; the coal ash structural fills; and the water test’s findings for LNHS.
“I hope the public will not see the three issues as comingled yet,” Johnson said.
From 1995 to 2016, Iredell reported to a state registry sometimes double – and even triple – the state average of thyroid cancer cases. That trend is under review.