NEWPORT — An unpleasant odor drifting from Newport’s wastewater treatment facility that permeated throughout the downtown earlier this week and closed the middle/high school Thursday is beginning to dissipate.

The smell stems from hydrogen sulfide in the facility’s two lagoons, which are used to treat sewage from the Newport’s roughly 1,100 users, Newport Town Manager Kyle Harris said in a phone interview Thursday.

“We had some bad weather issues,” which exacerbated the odor problem, especially on Tuesday, said Arnold Greenleaf, Newport’s wastewater superintendent, who has overseen the facility on Putnam Road for about 40 years. “We had cold and warm air, we had fog which held everything down.”

Donna Magoon, Newport’s school superintendent, decided to cancel classes at Newport Middle High School Thursday due to the odor.

“Many of you may already be aware, but earlier today, an odor from the Newport Wastewater Treatment Facility affected the Middle High School, leading to several students and staff experiencing nausea and headaches,” Magoon wrote in a letter to parents posted to the SAU 43 website. “While the smell has somewhat dissipated, it is still lingering throughout the school.”

Town officials said the odor has lessened since Wednesday.

“With a little bit of air movement you couldn’t smell anything at that point,” said Harris, who visited the lagoons Wednesday and Thursday morning. “It’s starting to work. The weather has been cooperative. We’ve got some cooler nights coming.”

In early October, the electric systems involved in the operation of blowers that power the aeration system failed. The system that faltered takes outdoor air and compresses it before injecting it into the two wastewater lagoons, which together can hold 21 million gallons. Aeration of the water keeps the water mixing and encourages the growth of aerobic bacteria that break down the waste.

Workers got the back-up blower running, but it later failed. They were left to chase down parts for the system, which is from the mid-1980s and was made by a manufacturer that is no longer in business, Greenleaf said.

The aerator system ordinarily runs 24/7. Greenleaf estimated that it was turned off for a total of two weeks during the last month as staff worked to repair it. Sometimes it would get up and running again, only for another part to stop working.

“It was like one of those projects you just can’t finish,” Greenleaf said. “You think you’ve got it and the next morning you learn you don’t have it.”

The issues that caused the odor started around Oct. 27, when a belt on the back-up system failed. It took until Tuesday to get the system working properly, Greenleaf said.

Because the lagoons sat undisturbed for the better part of a week, when the aeration was turned back on, all the settled sludge was stirred up and the resulting hydrogen sulfide gas created by anaerobic decomposition was released. It takes a while for the lagoons to catch up after sitting stagnant for a while.

The stench at its worst also coincided with Election Day: Newport Middle High School on North Main Street, a short drive away from the wastewater facility, is the town’s only polling location. Kate Luppold, who lives in downtown Newport, said she had noticed the smell over the last month, but it was only when she was volunteering at the polls that it became stronger.

“It hasn’t been bad, but on Tuesday it wasn’t pleasant,” said Luppold, who said she got a headache from the odor. “Since the fix has started, our town has done a really good job with social media and sharing updates. We all know it will take a few days to dissipate, but it has started dissipating.”

On Wednesday, Newport town officials notified the New Hampshire Department of Environmental Services about the odor, said James Martin, a spokesman for the department.

“We’re going to stay in close contact with staff up there, if they need any technical assistance from the state we’ll be there to help them with that,” Martin said. “Anyone concerned about any symptoms they may be having, the best thing they can do is to reach out to their health care provider.”

The town is also working on tracking down a better blower to help alleviate the pressure on the back-up system. New blowers cost around $60,000, Harris said.

“Even with that, there’s still significant lead time to get it,” he said. “We’re looking to see if we can find a used one. If we can find a used one, it could be here relatively quickly.”

The cost of the repairs will be covered by the town’s operating budget, Harris said.

There is also more help on the way. In September, Newport voters approved spending $5 million in state money to upgrade the wastewater treatment plant. Town officials told residents on the ballot that there would be “no tax impact from this article.”

The project is expected to begin later this month and be completed in November 2026, Harris said.

“I think, probably as unfortunate as it was that the smell got so bad on Tuesday, we did have a remarkable number of voters from Newport experience it by being so close to the smell,” said Luppold, who is also executive director of the nonprofit Library Arts Center in town. “I think that would definitely solidify that there definitely is a need to update the system.”

Valley News photographer James M. Patterson contributed to this report. Staff writer Liz Sauchelli can be reached at esauchelli@vnews.com or 603-727-3221.