Town officials in Windham have begun working with surrounding communities and several state departments to clean up the chloride levels in four local watersheds.

Policy, Dinsmore and Beaver brooks, along with a western tributary of Canobie Lake – part of the Policy Brook and Beaver Brook watersheds within the Interstate 93 corridor – have all come under scrutiny by the New Hampshire Department of Environmental Services after a yearlong study found significant water- quality violations.

Now officials at DES are asking local and state authorities to work together as part of a salt-reduction work group to find a solution to the unacceptably high level of chloride in the watersheds. see these readings, and, in order to get a handle on it, we did the year-long monitoring program. Automated samplers were put into the streams and took measures every 15 minutes,” said Eric Williams, watershed assistance section supervisor.

“Almost all of it is due to winter road and parking lot maintenance.”

While there are a few insignificant sources of chloride, like atmospheric deposits, food waste or water softeners, about 50 percent of the salt leaked into the watersheds is attributed to private roads or parking lots and another 30 to 40 percent from public roads. State highways contribute about 15 percent, Williams said.

The acceptable chloride level is 230 milliliters per liter. Over the past year, Policy Brook had chloride levels 25 percent over that limit on average, Williams said.

Though the high levels of chloride do not pose a significant health risk to humans, it does pose a threat to fish and other aquatic organisms.

To meet water quality levels, about 40 percent of the chloride found in the water would need to be removed, but because chloride in the runoff cannot be treated, there is no method of taking the salt out of the system, according to Williams. Reducing the amount of salt used to keep roads and highways clear during winter storms presents the most viable solution over time, he said.

The salt reduction work group – made up of municipal representatives from Windham, Salem, Derry, Londonderry and Chester, as well as the New Hampshire Department of Transportation – was an effort to begin pushing towns toward finding affordable ways to reduce the amount of salt used during the winter months.

“How do we do this thing is as a collaborative effort?” said David Poulson, transfer station manager and one of Windham’s representatives in the work group. “I think its too early to figure out how this is going to unfold. I just know we’re at the point that we’re going to have to implement these changes.”

DES officials are considering implementing total maximum daily limits on the amount of salt each community can use, Poulson said, which means Windham will have to explore new options to keep the roads free of snow, including using brine or sand rather than salt.

“Windham blends chloride and sand, unlike a lot of communities. We do our part to reduce chloride and that’s been our method for a long long time. We’ve tried the best available technologies. Is that enough? No,” Poulson said. “We did things on the sand-salt blends, alternative treatments, and it comes down to dollars and cents. There’s not a perfect solution, but there may be a blending of solutions.”

Poulson is optimistic that collaboration with other communities as well as with the DOT will present viable solution for Windham. In the meantime, the town has purchased two new sanders that allow more control over how much of the sand-salt mixture is dispensed at any given time and according to Highway Agent Jack McCartney, the town has reduced the amount of chloride used on the roads in the vicinity of the affected tributaries.

On average the town uses about 3,500 tons of the salt-sand mixture – one part salt to every three parts sand – over the course of the winter. McCartney said. They have also begun evaluating storms to determine the precise amount of the mixture needed.

While Williams said there does seem to be a “healthy amount of skepticism” towards finding a cost-effective solution to keeping roads clear without using salt on the part of town officials, the offer of potential state grants and the level of regional collaboration have propelled them in the right direction.

“The towns think that they’re currently being fairly careful with their salt, which I think is true. For one thing they’ve got to purchase their salt. It’s the cheapest way of maintaining the road, but its still an expense,” Williams said. “The way that we’re approaching it is that this is going to be a long term program to try and achieve these reductions. If we see sign reductions of chloride in water bodies ten years from now I think we’ll be doing a good job.”