The water treatment facility on Little Simond Pond still pumps some water into the mostly well-fed system in Tupper Lake, causing the uptown water to exceeded state safe zones. (Enterprise photo — Aaron Cerbone)

TUPPER LAKE — Residents of this village received a notice last week that the municipal water, which was switched over to well water sourcing in June, exceeded the safe zone of by-products of the disinfection process.

While all village customers received the notice, which is mailed out every year, only the uptown area exceeds the limits, according to the village water department Superintendent Mark Robillard. This is because uptown is still getting its water supply supplemented from Little Simond Pond while the Junction is purely on well water. The station taking water from Big Tupper Lake has been closed.

Robillard said uptown water, though deemed to be over the safe zone by the state Department of Health, is the same water villagers have been drinking for years and is not any more dangerous. (Correction: An earlier version of this article incorrectly said the Department of Environmental Conservation deemed the water to be over the safe zone.)

“It’s not ‘not acceptable’ limits,” village Mayor Paul Maroun said. “It’s not water you have to boil, but you have to put people on notice.”

The water from the wells is fine, and the Junction’s water tested clean; however, the water from the wells gets mixed in with the surface water in the uptown lines and water tank, and tests over the limits. It is the treatment of the water that causes its levels to exceed the limits.

The reason the village switched to well water was because in 2014 the Health Department determined the village water was over the safe zone for by-products of the disinfection process. Organic materials such as leaves or algae can form trihalomethanes and haloacetic acids as water is treated with chlorine disinfection. Both these by-products have been linked to harmful side effects after prolonged exposure, including an increased risk for cancer.

Robillard said the water department is flushing lines out through hydrants to reduce the amount of pond water in the lines on the north end of town and to get more well water into those lines. Robillard said it may take a year or two to get all the pond water out of the pipes and that it will gradually dilute over time.

He added that freezing temperatures make it hard to flush in the winter and that the department will begin to flush the lines in earnest again in the spring.

Maroun said the village will re-test the water three times in next two months, and if the levels don’t come down, the village can temporarily shut down the Little Simond Pond intake plant to make sure the problem is coming from there.