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vsdimg01Commercial 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.

vsdimg02 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.

vsdimg03The 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 6 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, 11 other States have segments of their surface waters designated as NDZs. Those States are: California, Florida, Georgia, Massachusetts, Minnesota, New Jersey, Nevada, New York, South Carolina, Texas, and Vermont. 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.

As of January 30, 1980, if a vessel has an installed toilet (technically referred to as a marine sanitation device (MSD)), it must be equipped with one of three types of MSDs (http://www.law.cornell.edu/uscode/33/1322.html). The MSDs (Type I, Type II, Type III) are designed to meet different needs and effluent level requirements. Since portable toilets can be moved on and off a vessel, they are not considered installed toilets; therefore, vessels that have portable toilets are not subject to the MSD regulations.

Types of Marine Sanitation Devices

Sewage Treatment Device Vessel Length Standard
Type I- Flow-through device (maceration and disinfection) equal to or less than 65 feet in length The effluent produced must not have a fecal coliform bacteria count greater than 1000 per 100 milliliters and have no visible floating solids.
Type II- Flow-through device (maceration and disinfection) greater than 65 feet in length The effluent produced must not have a fecal coliform bacteria count greater than 200 per 100 milliliters and suspended solids not greater than 150 milligrams per liter .
Type III- Holding tank any length This MSD is designed to prevent the overboard discharge of treated or untreated sewage.
  • Type I MSDs rely on maceration and disinfection for treatment of the waste prior to its discharge into the water.
  • Type II MSDs are similar to the Type I; however, the Type II devices provide an advanced form of the same type of treatment and discharge wastes with lower fecal coliform counts and reduced suspended solids.
  • Type III MSDs are commonly called holding tanks because the sewage flushed from the marine head is deposited into a tank containing deodorizers and other chemicals. The contents of the holding tank are stored until it can be properly disposed of at a shore-side pumpout facility. (Type III MSDs can be equipped with a discharge option, usually called a Y-valve, which allows the boater to direct the sewage from the head either into the holding tank or directly overboard. Discharging the contents directly overboard is legal only outside the U.S. territorial waters which is 3 or more miles from shore.)

For more information, contact James Woodley, United States Environmental Protection Agency, 4504F, Oceans and Coastal Protection Division, 401 M St., S.W., Washington, DC 20460, (202) 260-1998, FAX (202) 260-9920, woodley.james@epa.gov

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