Expansion plans for the historic Shearer Cottage in Oak Bluffs remain undecided, as longtime family owners of the inn attempt to balance a stated need for economic survival with environmental impacts in a fragile watershed.

The Martha’s Vineyard Commission closed a public hearing Thursday night on the plan to substantially renovate and expand the historic inn situated in the Highlands section of Oak Bluffs. The newest plan calls for increasing the rooms from six to 15, among other things gut renovating the main cottage with five new bedrooms, replacing a separate one-story building with two new buildings, one with eight rooms, the other with two rooms.

Highlands inn is the first stop on the African American Heritage Trail of Martha's Vineyard. — Ray Ewing

Total square footage would increase from roughly 3,000 square feet to roughly 9,000 square feet. Extensive landscaping and some regrading is planned.

The applicant is Eric Van Allen, whose family has owned and operated the cottage for more than 100 years. The architect is Chuck Sullivan. The project is under review by the MVC as a development of regional impact (DRI).

The chief sticking point with the project is wastewater. Because the property lies in the watershed for the Oak Bluffs harbor and uses on-site septic disposal, nitrogen outputs are strictly limited. A plan to use some kind of innovative/alternative septic system remains under active discussion between MVC water quality planners and project engineer George Sourati. But even with a high-technology nitrogen-removing septic system and use of the property limited to six months a year with no outside public events, the nitrogen output would be slightly over what is allowed, according to Mr. Sourati.

As in the first public hearing held in October, history was on display Thursday night, with more than one impassioned speech about the deep historical significance of Shearer Cottage, which is featured in the Smithsonian’s National Museum of African American History and Culture, and is the first stop on the African American Heritage Trail of Martha’s Vineyard. The inn has been housing African American guests since 1912.

“It’s extremely important to stress the vital role Shearer has played in the Highland area for 100 years, and the need for it to continue to be economically viable,” said Elaine Cawley Weintraub, who is heritage trail executive director. “Every year people ask us, where can we stay in an African American place . . . there is never enough room at Shearer . . . This is African American history in our midst, and to ensure its survival the building does need modernization.”

Lee Van Allen, mother of Eric, also spoke in impassioned tones about continuing the long legacy of the cottage for future generations.

“It’s very important to us and who we are as a family for over 100 years,” she said.

Mr. Van Allen echoed the thoughts.

“My family goal is to preserve the legacy,” he said simply.

The MVC has received dozens of letters about the project, most of them supporting the expansion.

In the end commissioners closed the hearing but kept the written record open for two weeks to allow septic discussion to continue between the applicant and staff.

“I think we can work this out between staff and applicant,” commissioner Linda Sibley said.