NO DISCHARGE AREAS (NDAs): ELIMINATING THE LAST MAJOR SOURCES OF SEWAGE DURING DRY WEATHER

A No Discharge Area (NDA) is a federally approved state designation for a water body that prohibits the discharge of all sewage – treated or untreated – from any vessel. Under Section 312 of the Clean Water Act, a state can petition the Environmental Protection Agency to approve a NDA designation for some or all of its waters. EPA's primary responsibility is to determine whether adequate facilities for the safe and sanitary removal and treatment of sewage from all vessels utilizing the proposed NDA are reasonably available. This designation provides an added layer of water quality protection because it is already illegal to discharge untreated sewage in US waters.

Boats equipped with toilets are required to have a Coast Guard-approved Marine Sanitation Device (MSD). MSDs are designed to either hold the raw sewage in a holding tank (Type III) or to treat the sewage and discharge this effluent into the coastal waters (Type I and II). A NDA designation is intended to prevent the discharge of MSD Types I and II within the designated area. (Discharges from Type III MSDs are already prohibited within state waters). Effluent from properly functioning Type I and II MSDs has bacteria concentrations well above water quality standards set for swimming or shellfish harvesting. If the MSD is not properly maintained or operated, concentrations may be even higher. Sewage effluent from MSDs degrades water quality by introducing disease-causing microorganisms, nutrients, and chemicals. During dry weather, sewage discharges from vessels often represent the only possible source of sewage that can cause beaches and shellfish beds to be closed.

Maintaining pumpout infrastructure and educating boaters and marina operators are the foundation for the success of any NDA. In fall 2008, an evaluation of the Casco Bay NDA program was performed. At the time of this study, Casco Bay was the only NDA in Maine. The methodology for the evaluation was a multi-method approach utilizing three program evaluation instruments 1) mail-survey of Casco Bay boaters, 2) in-person survey of pumpout facility operators, 3) site visits of the Casco Bay pumpout facilities. Recommendations for the Casco Bay NDA program were made based on the overall research findings. The results from this study can be applicable to NDAs in any area – whether one wants to improve an existing program or to establish a new designation.