No Discharge Zones, or NDZs, are designated bodies of water where the discharge of all boat sewage, whether treated or not, is prohibited. All of Massachusetts waters are designated as “no discharge” for vessel sewage (see Massachusetts NDZ map [PDF 1 MB]).
The federal Clean Water Act (Section 312) requires the use of Marine Sanitation Devices on all commercial and recreational vessels that are equipped with installed toilets. Also called MSDs, these systems are the on-board equipment for treating and discharging or storing boat sewage. These Clean Water Act requirements do not apply to:
- Vessels with portable toilets ("porta-potties") or other portable sewage reception systems.
- Gray water from bath or kitchen sinks.
- Vessels beyond three miles from shore.
A Marine Sanitation Device or MSD is installed on vessels to treat, process, and/or store raw, untreated sewage for discharge overboard or collection by a pumpout. Any boat with an installed toilet must have one of the three types of U.S. Coast Guard approved MSD:
Type I - Provides on-board treatment for smaller vessels (<65 feet). After treatment the waste can be discharged overboard outside of an NDZ.
Type II - Provides on-board treatment for vessels >65 feet. After treatment the waste can be discharged overboard outside of an NDZ. Type II systems provide a higher level of treatment than Type I.
Type III - A holding/storage tank or similar device that stores raw sewage for collection by a pumpout.
Massachusetts State Law (323 CMR 2.07(6)) prohibits the discharge of untreated sewage from boats on or into waters of the Commonwealth—which typically extend three miles from shore. (Boaters should note that waters of the Commonwealth can extend beyond three miles from shore in areas of Massachusetts Bay, Cape Cod Bay, and Buzzards Bay—see NOAA Chart 13267 for the federal state boundary in Massachusetts Bay.) Boats with functioning Type I and Type II MSDs may discharge treated effluent in coastal waters unless they are in an NDZ. A Type III MSD or "holding tank" is the only type of MSD that can be used legally within an NDZ.
When traveling in NDZ waters, boaters with Type I or Type II MSDs must do one of the following:
- Close the seacock and remove the handle.
- Fix the seacock in the closed position with a padlock or non-releasable wire-tie.
- Lock the door to the space enclosing the toilet with a padlock or door handle key lock.
When traveling in NDZ waters, a Type III MSD (holding tank) must be secured in one of the following ways:
- Close each valve leading to an overboard discharge.
- Padlock each valve in the closed position.
- Use a non-releasable wire-tie to hold each valve leading to an overboard discharge in the closed position.
All of these methods of securing MSDs while in NDZ waters are approved by the U.S. Coast Guard.
Boaters with Type III MSDs can use any of the pumpout facilities located throughout the state. For the best service, boaters should call ahead to verify hours or to make an appointment for a pumpout.