A divided Chilmark conservation commission voted last week to approve a project to install a new culvert in Mill Brook headwaters off North Road.

Proposed by the Sheriff’s Meadow Foundation, the project has kicked up a cloud of controversy among neighbors and abutters, who have registered concern about the impact on neighboring wells and bordering wetlands in a long string of correspondences.

First proposed by the foundation in 2016, the project will remove two small metal culverts at the headwaters of Mill Brook — an up-Island stream that originates beside Old Farm Road — and replace it with a larger concrete culvert to encourage fish and wildlife passage in the brook.

The project would also drain 30 cubic yards of sediment from the brook area and construct a new pilot channel upstream of Old Farm Road, according to the Sheriff’s Meadow proposal.

Concern over impacts to abutter Frank Dunkl’s property, which contains a spring water source designated as a possible emergency water supply for the up-Island towns, has become a focal point in the debate.

At a hearing last Tuesday, the conservation commission continued discussion on the culvert replacement.

Mr. Dunkl reiterated his strong objections to the project, engaging in exchanges with project engineers about possible damages to bordering wells and wetlands, and calling for additional study.

“As I’ve been screaming since the beginning of this project . . . we need to do groundwater temperature measurements and value of flow,” said Mr. Dunkl, who formerly owned and ran the Chilmark Spring Water Co. “I’m trying to do what I think is right for the environment and also trying to protect the water supply, which I believe could be a beneficial interest to the community, not just to some fish.”

Rebecca Haag, executive director of Island Grown Initiative, which owns Mr. Dunkl’s property as part of a life estate, also spoke against the project, noting concerns about jeopardizing the emergency water supply.

“The one issue that continues to be not addressed by Sheriff’s Meadow has to do with the idea that we do have a public water source,” Ms. Haag said. “There’s no guarantee that if that well is ruined that we can get state certification on a different well.”

Ms. Haag also raised worries about potential damage to neighboring wells.

Sheriff’s Meadow has agreed to redrill any wells affected by the project to a deeper depth, and plans to offer a $100,000 bond to neighbors in the event of well damage, but Ms. Haag called the offer insufficient. Steve Bernier, Thomas Bena and lawyers from the West Tisbury firm Brush Flanders and Moriarty all spoke against the proposal as well.

But Nicolas Wildman, who spoke on behalf of the state Division of Ecological Restoration, defended the project and the feasibility studies that were done.

“I think we’ve made it perfectly clear how this project fits in with state and local regulations, despite assertions otherwise,” Mr. Wildman said. “Our our work and analysis on this . . . is perfectly in line with modern professional standards.”

Nick Nelson of Inter Fluve — a company assisting in project planning — pointed to the culvert upgrade as a bulwark against climate change.

West Tisbury resident Prudy Burt echoed the sentiment. “This is about restoring natural function to this historic wetland system,” she said.

Commissioner Pamela Goff endorsed the project’s ecological benefits, and while other members had questions about environmental studies and available protection for abutters in the event of well damage.

After more than an hour of discussion, commissioners voted 4-2 to approve the project pending a final review of the plan’s impact on the emergency water source by the Massachusetts DEP.

Ms. Goff, Russell Maloney, Sandy Broyard and Candy Shweder voted yes, and chairman Chris Murphy and Joan Malkin voted no.