Amidst public scrutiny of NStar’s vegetation management practices, senior arborists from the utility company addressed concerns of Tisbury residents at a meeting on Tuesday of the board of health.

The company’s procedures, which include targeted application of herbicides, have raised alarm among Cape and Islands residents who worry about the environmental effects of the chemicals.

NStar representatives answered questions for nearly two hours in attempts to reassure the town about herbicide practices. They discussed their chemical application schedule and technique, the toxicity levels of the herbicides used and opportunities for public comment on the issue. But trust remained tenuous. Attendees described, often passionately, their qualms about the use of herbicides under the utility lines in town.

“I am really terrified, I guess is the best I can come up with,” said Lyndsay Famariss, a Tisbury resident whose son often searches for lost sports balls in the right of way near her home. “The idea of people coming out and spraying in my neighborhood is something that doesn’t feel safe.”

“From my perspective, nobody knows the consequences of applying these chemicals,” said Paul Lazes, also a Tisbury resident.

Arborists Bill Hayes and Paul Sellers, who direct NStar’s vegetation management, which has after a four-year moratorium reinstated the application of herbicides, assured attendees that their program was considered best practice in the field.

Further, they said their plans did not currently include any vegetation management within a three to five year window. But while they committed to very limited spraying, if any, on the Vineyard in the next three years, the paperwork is more ambiguous. The company’s annual plan for 2014 allows for “touch-up” work in West Chop and off the Edgartown-Vineyard Haven Road.

The town had concerns about the practice in general, including the spraying that has already taken place between Nov. 18 and Dec. 3.

When pressed to defend the safety of the products used on rights of way, the NStar representatives emphasized that the chemicals were both approved by the state for use in sensitive areas and registered with the Environmental Protection Agency. They also reassured the town that company policy dictates that herbicides are not applied within 400 feet of wetlands areas.

Melinda Loberg, president of Tisbury Waterways, said she’d been told that the chemicals were dangerous to invertebrates.

“Some of the rights of way come close to the Tashmoo area,” she said.

Mr. Hayes said the chemicals were applied to plant foliage, and never to the ground where runoff might occur if applied in excessive doses.

“There is no runoff,” he said. “There is no getting down to the groundwater and coming up in the pond.”

On windy days, drift control agent is applied to the tank mix, he said.

Craig Saunders, a groundwater consultant, asked if the company might commission a study of the effects of the chemicals on the groundwater.

“Generally when we have projects on the Vineyard, we require some monitoring,” Mr. Saunders said. Adding later, “It would give us a lot more confidence that in truth, these products don’t have an effect on the groundwater.”

Ultimately, the arborists said they were not chemists, and functioned as the end user of the products. “We don’t want to hide behind that, but we are licensed to apply these herbicides,” Mr. Hayes said. They directed specific safety questions to the state, which could answer them more “precisely,” they said.

Mr. Lazes asked about the use of grazing animals to keep vegetation in check. Public Service, a utility company in New Hampshire, used as many as 1,200 sheep to maintain their utility rights of way in the early 2000s. Vineyarders wanted to know Tuesday whether a so-called grazing power project could be replicated here.

“I have watched them decimate plant life; they are very effective,” said Jefferson Munroe, a resident and farmer.

But the arborists said that after a study of the grazing technique had deemed this strategy ineffective by Northeast Utilities (NU), the parent company of NStar. They added that the use of mechanical controls, or cutting vegetation back, was not effective on its own.

The most recurrent issue was unease about the lack of communication surrounding the vegetation management.

Mr. Sellers said 48 hours before the application starts, the company places an advertisement in a newspaper of record, which the state had determined to be the Cape Cod Times.

Islanders lobbied instead for notification of sprayings to appear in the local papers of record, and not the Cape Cod Times, which they said was little read on the Vineyard.

“I have lived here for 21 years, and I have never once read the Cape Cod Times,” Ms. Famariss said. She added that she didn’t know anyone else in her age group who did. “I feel like the first step, if you do want to open up the lines of communication, is to communicate with us.”

The representatives said they would strongly recommend the shift to their management.

NStar also repeatedly referred comments to the department of agricultural resources (MDAR), a state agency that oversees the creation and implementation of their vegetation management plans. MDAR is currently reviewing the yearly operational plan for 2014, which allows NStar to apply herbicides in three Island communities including Tisbury, Oak Bluffs and Edgartown.

The agency accepts comments on the plan until January 5, and may extend this deadline as they did for the 2013 plans.