Ballast Water Management on the Great Lakes
The authors of a three-year study recommend that "saltwater flushing," the practice of rinsing a ship's ballast tanks with deep-ocean water before it enters the St. Lawrence Seaway, be added to a set of requirements called the Code of Best Practices for Ballast Water Management. In 2002, the St. Lawrence Seaway corporations in the United States and Canada adopted rules making compliance with the code mandatory for entry into the seaway.

In 2005, the U.S. Coast Guard issued a policy statement encouraging mid-ocean ballast tank flushing. Last year, Canada adopted management regulations requiring that ballast water---including residual water in NOBOBS---be treated with saltwater or salt---before the water is discharged in the Great Lakes.

Ballast Water is a Global Issue
Ballast water has received considerable attention globally over the past several years. When ships uptake ballast water, small marine organisms and sediment suspended in the water can be captured in the ballast
water. Ships could then transport these organisms, often in a viable condition, across natural biological barriers to other areas where they are released and may become invasive. Efforts to prevent and curb the
introduction of aquatic nuisance species (ANS) are taking place at international, national and local levels. The Marine Environment Protection Committee (MEPC) at the International Maritime Organization (IMO) and
other related subcommittees have made significant progress toward an international ballast water management policy which includes a ballast water discharge standard.

Even when fully loaded with cargo, ships commonly referred to as NOBOB’s (No Ballast on Board) are rarely completely empty of ballast water. There is clearance below the bell mouths of the ballast lines in the ballast tanks to avoid clogging that makes some water un-pumpable using standard ballast pumps. This residual ballast water can be a mixture of water and sediment from ports recently visited around the globe. The residuals may be transported to the next port of call and become resuspended in the ballast water during subsequent ballast uptake.

Ballast Water Management on the Great Lakes Seaway System
When ships declare “Ballast Water on Board” (BOB ships) they are inspected during each Seaway/Great Lakes transit. BOB ships are inspected prior to entering the Seaway/Great Lakes on their initial transit each shipping season. The inspection is done before the ship is granted permission to transit the Seaway/Great Lakes system. Every subsequent transit of a BOB ship that does not intend on stopping at a St. Lawrence River port is inspected between the two US Locks (Snell and Eisenhower) to ensure compliance with ballast water regulations.

Regulatory bodies test the salinity in certain ballast tanks in order to confirm that the salinity meets the minimum required salinity of 30 ppt (parts per thousand). Ships that do not comply with the minimum salinity of 30 ppt are required to retain all non-compliant ballast water onboard, return to sea and conduct a full ballast water exchange or treat the non-compliant ballast water with an approved treatment.

On arrival in the Great Lakes Seaway System, ships declaring “No Ballast on Board” generally off-load cargo in ports in the lower lakes and thereafter take on ballast water and proceed to a series of Great Lakes ports in the upper lakes to pick up and/or off-load additional cargo (and ballast water). During these short voyages, the residual un-pumpable ballast water from overseas ports is mixed with Great Lakes ballast water and can be discharged into the ports of call in the upper lakes where cargo is generally loaded.

The trading patterns of transoceanic ships (“salties”) to the Seaway reveal a possible route for the introduction of ANS. For example, cargos such as iron and steel products carried by “salties” generally arrive from ports in Belgium, the Netherlands, Brazil, France, Germany, Russia, Poland, Spain, Turkey, and the United Kingdom.

It is common for ships to discharge part of their cargo at lower-lakes ports as they travel farther west in the Great Lakes basin, taking on more ballast water as they unload cargo. From their final discharge port, the “salties” normally transit in a ballast condition to pick up cargo for their outgoing voyage. The cargo is then transported to overseas ports, in Belgium, the Netherlands, Algeria, Italy, Spain, Venezuela, and the United Kingdom, amongst others.