WASHINGTON (AP) – Federal officials have agreed to a request by two Indian tribes for special protections for Nantucket Sound, a move that could delay construction of a proposed offshore wind farm off Cape Cod.

The National Park Service on Monday said Nantucket Sound is eligible for listing in the National Register of Historic Places due to its significance as a traditional cultural property.

The Mashpee and Aquinnah Wampanoag tribes say the designation, which would come with new regulations for activity on the sound, is needed to preserve the tribe’s sacred rituals, which include a clear view of the sunrise across waters where the turbines for the Cape Wind project would be built.

Plans to build 130 wind turbines across a 25-square-mile swath of federal waters about five miles from the Cape Cod coast have generated a long-running public fight.