The EPA-designated No Discharge Zones (“NDZ’s”) refer to the areas where the discharge of sewage even after it is treated using MSD I and II type waste management systems. In concert with the relevant states, the EPA has created NDZ’s to protect particularly vulnerable areas from even treated discharges. And it is expanding the number and coverage of those NDZs as sufficient pump-out stations become available.
MSDs are onboard Marine Sanitation Devices. Type 1 and Type II MSDs are macerator-type waste treatment systems that grind up the solids and disinfect the waste – by reducing the coliform count to levels low enough to not pose a health hazard. These MSDs use chlorine-based products that need regular replenishment. Type III MSDs are just blackwater holding tanks without any treatment - what one finds on most pleasure craft. Portable toilets found on very small boats are just mini holding tanks that need to be physcially dumped ashore.
