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 Commercial and recreational boating play an important role in American society. Unfortunately without proper management, these activities can contribute to water quality degradation. One type of degradation is the increased concentration of fecal coliform bacteria (found in the intestinal tracts of all warm-blooded animals). The discharge of untreated or partially treated human wastes from vessels can contribute to high bacteria counts and subsequent increased human health risks, and these problems can be particularly bad in lakes, slow moving rivers, marinas and other bodies of water with low flushing rates. When concentrations of fecal coliform bacteria rise above safe levels, local health boards act to close swimming areas. A fecal coliform bacteria count of 14 (or greater) MPN per 100 milliliters of water results in the closing of shellfish beds.
 The impact of sewage on delicate coral reef communities is also a concern. Excessive amounts of nutrients from improperly treated sewage can harm coral reef ecosystems by overstimulating the growth of aquatic plants and algae. When the stimulation of algal growth is prolonged, the corals are smothered and die beneath the thick cover of algal growth. This, in turn, affects the fish and other organisms using the area, leading to a decrease in animal and plant diversity and affecting use of the water for fishing and swimming. Pathogens, which are disease-causing microorganisms such as viruses, bacteria, and protozoans, can scar and cause disease in many species of corals. These microorganisms can enter water bodies through the discharge of inadequately treated sewage from vessels (as well as from other sources such as runoff or inadequately treated effluents from sewage treatment facilities).
EPA, the Coast Guard, and States work together, under Clean Water Act Section 312 (hereafter referred to as "Section 312"), to protect human health and the aquatic environment from disease-causing microorganisms which may be present in sewage from boats. Section 312  provides States with a tool to protect their citizens and aquatic habitats through standards for marine sanitation devices (MSD) - boat toilets or heads - and no-discharge zone designations for vessels.
 The availability of sewage pumpout stations, the importance of the waterbody for human health and recreation, and the desire for more stringent protection of a particular aquatic ecosystem are important considerations in the designation of no-discharge zones (NDZs) for vessel sewage. A graphic pumpout symbol is often placed at docks and marinas to show boaters where a pumpout facility is located. In some cases, small boats are used as mobile pumpout facilities. These boats carry the waste to an onshore reception facility.
Vessel sewage discharge is regulated under Section 312 . A State can have all or portions of their waters designated as a no-discharge zone for vessel sewage to achieve any of the following 3 objectives: (1) to protect aquatic habitats where pumpout facilities are available; (2) to protect special aquatic habitats or species [the State does not have to show that there are reasonably available pump-out or dump stations]; and (3) to safeguard human health by protecting drinking water intake zones [the State does not have to show that there are reasonably available pump-out or dump stations].
Currently 7 States have all (or nearly all) of their surface waters designated as NDZs. Those States are: Michigan, Missouri, New Hampshire, New Mexico, Rhode Island, and Wisconsin. In addition, 14 other States have segments of their surface waters designated as NDZs. Those States are: Arizona, California, Connecticut, Florida, Georgia, Maryland, Massachusetts, Minnesota, New Jersey, Nevada, New York, North Carolina, South Carolina, Texas, and Utah. Approximately 50% of the NDZs are in fresh water and the other 50% are in salt or estuarine waters. See the table on Types of Marine Sanitation Devices.
For more information, contact the
US Environmental Protection Agency, 4504T,
Oceans and Coastal Protection Division
1200 Pennsylvania Avenue NW
Washington, DC, 20460
or call 202/566-1200.
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