No Discharge Zones
The following is taken from Mass.gov: No Discharge Zones
Boat sewage can contain bacteria and viruses, nutrients, and chemicals that can be harmful to water quality and public health. No Discharge Zones, or NDZs, are designated bodies of water where the discharge of all boat sewage, whether treated or not, is prohibited. In 2014, the U.S. Environmental Protection Agency (EPA) approved the state’s designation of all of Massachusetts waters as an NDZ—capping 22 years of extensive work by the Massachusetts Office of Coastal Zone Management (CZM) and coastal communities and their partners to ensure the necessary waste pumpout facilities are available for boaters to use.
No Discharge Zones (NDZs) directly address the human health and environmental concerns created by the release of boat sewage into coastal waters. Sewage wastes discharged from boats can contain microorganisms (bacteria, viruses, and protozoans), nutrients, and chemical products—all of which can have harmful effects upon aquatic life and water quality.