Marine Vessel Sewage Discharge


Marine Vessel Sewage Discharge


The discharge of marine vessel sewage into waterways is a serious threat to the environment and to human health. Sewage may contain disease-causing micro-organisms (pathogens), such as bacteria and viruses that can cause diarrhea, dysentery, hepatitis and other serious illnesses or even death in humans.

Sewage discharged into water close to shellfish beds can result in public health concerns. Shellfish, being filter feeders, accumulate sewage pathogens in their tissues, so that when they are eaten, pathogens are transferred to the consumer at high concentrations. Some diseases associated with eating contaminated shellfish are dysentery, typhoid fever, infectious hepatitis, and gastroenteritis.

Sewage is very high in nutrients. High levels of nutrients in the water over-stimulate plant growth, depleting oxygen and resulting in algal blooms, foul odours, and fish kills. This problem tends to be more pronounced in enclosed waters with low flushing rates such as lakes, slow moving rivers, and marina basins – areas where boaters gather to anchor, swim, and fish.

Coral reef communities are particularly sensitive to the effects of improperly treated sewage. Prolonged overgrowth of aquatic plants and algae smother the coral and cause it to die. Fish and other creatures depending on the coral reef die off, resulting in a decrease in biodiversity and reducing the quality of the water for swimming and fishing. Even if the coral survives, it may become scarred and diseased by the pathogens in sewage.

What many boaters don’t realize is that marine vessel sewage is much more concentrated than domestic sewage because much less water is used per flush. According to the U.S. Environmental Protection Agency (EPA), the amount of bacterial pollution (fecal coliforms) from one weekend boater’s discharge of untreated sewage is equal to the amount from the treated sewage of 10,000 people during the same time period!

Vessel sewage discharged into waterways can be visually disgusting and renders the water unsafe to use for sports like swimming, snorkeling and water skiing. Nobody should allow vessel sewage to be discharged into recreational waterways. Violations should be reported so that clean water is available for all to use and enjoy.

Boaters can help by:

  • installing and using a Coast Guard-certified Marine Sanitation Device (MSD) appropriate for their vessel and the water body where it will be used. There are many types available. Some use holding tanks which require pumping out. There's also a hull-shaped composting toilet available which greatly reduces the need for pumping out.

  • learning to maintain and use their MSD properly

  • using on-shore restroom facilities whenever possible instead of onboard ones

  • encouraging marina owners and operators to provide adequate pump-out and dump facilities

  • learning how to use marina pump-out stations

Marina Owners and Operators can help by:

  • making boaters aware that sewage discharges can result in beach closures, shellfish contamination, and reduced opportunity for recreational activities

  • providing clean, safe on-shore restroom facilities for boaters

  • maintaining adequate pump-out and dump facilities and encouraging their use. The Ontario Marina Operators Association publishes a listing of working pump-out facilities (1-800-579-BOAT)

Everyone can help by:

  • reporting violations to their local Coast Guard station (in the phone book)

Written by: Nancy Harrington

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