Bow’s municipal water wells in some areas are turning salty due to ice-melt runoff, raising concerns for residents with health conditions.

At last week’s select board meeting, Tom O’Donovan, chair of the Drinking Water Protection Committee, said that the best way to curb this contamination is by reducing salt usage in the wellhead protection area, a zone where groundwater flows to municipal wells.

This critical area spans approximately two and a half to three square miles, from Vaughn Road to Briarwood Drive.

Around 100 residents, along with about 100 other users including employees and visitors, could be drawing from the same groundwater as the Bow Municipal System.

“If we don’t do anything, it’s possible that the salt contamination in our water system will continue to rise,” cautioned O’Donovan. “The worst case would be that they continue to rise and the other case possible is they stay high.”

Currently, the salt content in these wells averages 440 milligrams per liter, far exceeding the EPA’s recommended advisory level of 20 milligrams per liter for those on a “no salt diet” due to high blood pressure or specific health conditions. The EPA also suggests a secondary standard of 250 milligrams per liter for chloride, which can cause a salty taste in water.

Despite the town’s Green SnowPro Certification and its efforts to use a sand-salt mixture to minimize road salt application during winter storms, salt levels in the wells have continued to climb.

Water testing data also revealed that the salt content spiked to 580 mg/L between 2022 and 2023.

O’Donovan attributed some of the spikes in salt levels to the increasing frequency of ice and snowstorms affecting New Hampshire. Currently, the town uses a mix of salt with sand to provide effective traction on roads during snow and ice storms, ensuring safety while reducing the overall amount of salt applied.

O’Donovan proposed additional measures, such as the use of brine spreaders, which apply saltwater more efficiently and require less salt for effective deicing.

Another issue is the significant amount of road salt applied on Route 3A, which falls under state jurisdiction rather than the town of Bow.

“There’s a lot of salt on Route 3A,” said Donovan. “We don’t know if the Route 3A operator is Green SnoPro certified and that’s one thing we’d like to find out.”

Other potential sources of salt include local businesses using salt on parking lots and sidewalks, as well as water softeners, which contribute minimally but are still a factor.

The committee has ruled out natural salt deposits as a significant source of the contamination because in south and central New Hampshire it is rare.

Other recommendations from the committee include continuing to test wells for sodium and chloride and monitoring, seeking funding for water protection and salt mitigation strategies, verifying that the salt’s grain size and distribution meet specifications and collaborating with state and federal agencies.

This issue extends beyond Bow, affecting many towns and cities across New Hampshire.

The next steps involve the select board reviewing the recommendations and meeting with the State Department of Transportation.

“It sounds like a very complex issue,” said Angela Brennan, select board chair. “I want to make sure we as a town are within our capacity to handle it in the best way we can but perhaps there are other ways.”