Citing public safety issues and protection of a nearby pond and stream, the Aquinnah zoning board of appeals this week unanimously approved a variance that will allow a portion of Old South Road to be paved.

The variance was allowed with a series of conditions.

Dukes County and the Wampanoag Tribe of Gay Head (Aquinnah) sought an exception from a town bylaw which protects Old South Road, Old Lobsterville Road and Old Church Road as historic places and prohibits paving on them.

Two permanent speed bumps on the new strip of pavement and a proposed maintenance plan to be approved by the town selectmen, county commissioners and tribal council are conditions of approval.

Bret Stearns, natural resource director for the tribe, argued paving the road will prevent further sediment runoff into Occooch Stream and Pond, and the board agreed.

“We need good reasons to give variances,” board chairman Jim Vercruysse said at Tuesday’s hearing. “The way the road is now, it’s causing environmental damage and this is a remedy for it. It’s not the only remedy but it’s the best remedy according to the engineers . . . we understand the character issues and concerns of people but we’re also concerned about the environmental issues here in the stream and the pond and that’s an important part of town,” he said.

“And it also makes a section of the road safer,” added board member Peter Ives. “When it washes out it’s impassable.”

The project is a joint effort involving the town, the tribe and the county, the owner of the road. Old South Road dates back to 1870 as one of the principal byways of the town. It is home to both tribal and nontribal families as well as the site of several affordable homes.

The project involves paving the road and installing vegetative swales on each side of the road. A 320-foot section of road that slopes down toward Occooch Stream will be paved and be 10 feet wide; a series of interconnected catch basins have already been installed to hold the runoff. A small leaching area will be installed at the end of the road to prevent overflow into a protected wetland.

The vegetative swales were dug the first week of June, and are expected to be planted in the fall.

Construction stopped late last month when an abutter raised the bylaw issue with building inspector Jerry Wiener.

Residents were split over keeping the dirt road as a part of the rural character of the town and paving it to protect the ecosystem of the pond. A number of Old South Road residents attended a public hearing two weeks ago to voice their concerns.

The speed bumps were one of the requests to deter drivers from using the road as a shortcut to the beach.

In a letter to the board, residents Lisa and Buddy Vanderhoop said they supported the project.

“We hope to see the sediment removed from Occooch Stream in the future,” they wrote. “We believe the pavement is the best option for the project and the narrow width will not detract from the rural character of Old South Road.”

The tribe received a $200,000 grant from the EPA for the project, but Mr. Stearns estimates it will take an additional $600 for maintenance in the first two years and $400 in the third year. Mr. Stearns said the reason for the short-term plan is to see what work will be needed to monitor the catch basins and empty them and how much sediment will build up. After three years, the town will have to pay for the upkeep.

Included in that cost is annual trimming of the vegetative swales. Board member Vern Welch said the road has been getting wider and the swales would stabilize it.

The town will continue to be responsible for plowing the road.

Mr. Stearns also said they would be willing to fill in with crushed stone the section of road that leads to Church street.

The maintenance plan will now go before the selectmen, county commissioners and tribal council for approval.