ROCKLAND — The Island Institute has announced its intention to oppose the construction of an 84-slip marina on Bass Harbor’s working waterfront at the southern tip of Mount Desert Island.

In a letter sent to Maine’s Bureau of Public Lands and Department of Environmental Protection, Philip W. Conkling, executive director of the Island Institute, presented evidence demonstrating that the proposed marina would “cause irrevocable changes on a valuable marine habitat.” Conkling went on to say that the proposal would violate the state’s public trust doctrine as well as the standards of the Natural Resources Protection Act regarding navigation and coastal wetlands impact.

The institute’s intervention comes at the request of Bass Harbor fishermen and the Citizens for Tremont, an organization of concerned residents. On June 26, the Tremont Planning Board voted 4-1 to approve the marina as permissible within the town’s present shoreland zoning ordinances.

According to Pattie Tierney, a Citizens for Tremont spokesman, the intervention has the broad support of the local fishing community, 40 of whom signed a petition July 12 expressing opposition to the marina and whose interests would be most directly affected by the marina.

On June 21, the Tremont Harbor Committee voted to oppose the project on the basis of the impact the marina would have on navigation in the narrow harbor channel and traditional mooring areas.

In accepting the invitation to enter the case, Conkling said, “The Bass Harbor decision underscores the inequality of the odds when local citizens’ boards and weak ordinances come up against developers’ strong-arm tactics. The scenario in Bass Harbor could just as easily be played out in any of a number of island working harbors, such as Carvers Harbor on Vinalhaven, or Burnt Coatcq Harbor on Swans Island.

“In turning to the state regulatory process for assistance,” said Conkling, “the Island Institute hopes to establish an additional set of safeguards for island communities struggling to preserve traditional island lifeways and the character of their working waterfronts.”

In addition, Conkling said that the proposed marina was another major instance in which mainland issues directly influence island communities. In this case, the proposed marina would have an immediate impact on neighboring Swans Island and Frenchboro, because the site is directly adjacent to the already narrow and congested ferry-access road.

Moreover, according to Conkling, in an inevitable ripple effect, the development of a major marina within easy striking distance of these two islands would intensify the pace of recreational boating development already under way in these embattled working harbors.

The summer residents of nearby Gott’s and Black islands also would feel the pressure from this recreational expansion, he said.