SCITUATE - Town officials say a malfunction at Scituate’s wastewater treatment plant Wednesday night caused partially treated sewage to be dumped into the North River.

The town alerted residents to the spill Thursday afternoon, saying that that it had corrected the problem and was working to test water in the North River. Town officials were still waiting for those results Friday.

"I’m hoping that the amount that came out was very minimal and we don’t have anything major," said Kevin Cafferty, Scituate's public works director.

Cafferty said the malfunction occurred in a bank of ultraviolet lights meant to keep any bacteria in treated water from reproducing. He said the water released Wednesday had been through three other stages of treatment.

"It was by no means raw sewage or anything like that," Cafferty said.

Cafferty said the bank of lights went out for around three hours Wednesday night, perhaps because of a power surge. Officials don't yet know how much water was released into the North River without receiving the ultraviolet treatment, but Cafferty said sewer flows at night are typically low.

While officials await the water test results, the North and South Rivers Watershed Association is advising people to avoid parts of the watershed near where the sewage was dumped, which includes the Herring River and the mouth of the North River, home to a beach known as "the spit."