Boats sailing through Pleasant Bay and Chatham Harbor are being banned from discharging sewage.
The Environmental Protection Agency has approved a request from the state to designate the waters a “no discharge area.”
Massachusetts Environmental Secretary Ian Bowles said the designation adds to the administration’s goal of barring the discharge of boat sewage in all of the state’s coastal waters.
Bowles said the ban protects one of the most diverse and productive marine habitats on the East Coast.
The EPA is considering a similar ban from Gloucester to Salisbury.
More than a dozen locations in Massachusetts have already been designated “no discharge areas” as have all state marine waters in Connecticut, Rhode Island, and New Hampshire.