Ballast Water Exchange: A Complex Problem

According to U.S. Coast Guard data, NOBOBs represent over 70 percent (74 percent in 1999, 72.1 percent in 2000 and 68.5 percent in 2001) of incoming ships to the Great Lakes - St. Lawrence River system. These NOBOB ships are fully loaded with cargo and as a result their ballast tanks contain minimal (generally less than 3 percent) residual untreated ballast water and sediment. Yet even these small residues can be contaminated with alien invasive species. Both a Transport Canada study and a more recent study presented at the 11^th International Conference on Aquatic Invasive Species in 2002 reported finding live organisms in virtually all ships that reported as NOBOB.¹³ Clearly, current ballast water regulations are not sufficient to eliminate the risk these vessels pose.

Transit of a NOBOB Steel Carrier The yellow arrows indicate the path of a NOBOB ship on an inbound trip, showing points where the ship unloads steel and takes on Great Lakes water as ballast (stability). The blue arrow indicates the final inbound leg of the trip on the Great Lakes. The ship is now empty of cargo and fully loaded with Great Lakes ballast water. Taking on ballast water on the lower lakes provides an environment for cysts or eggs of invasive species remaining in residual ballast water and sediment to hatch.

• Chart: NOBOB Ships on the Great Lakes
  
  The Great Lakes receive ballast water discharged from ships transiting the system. Fully loaded ships carrying only residual ballast water (NOBOBs) unload cargo and take on ballast water for stability and trim. When these ships take on new cargo, they discharge ballast water to attain stability. Lake Superior has increasingly become more important as the initial site of ballast water discharged to the lakes from ships transiting the system.

In addition to the U.S. regulations requiring ships bound for the Great Lakes to exchange ballast water in the open ocean, Canada and the U.S. also have voluntary guidelines designed to minimize the uptake and release of harmful aquatic organisms, pathogens, and sediment in ballast water.¹⁴ The guidelines suggest precautionary practices to avoid the uptake of ballast water in areas near sewage outfalls, in areas with known outbreaks or infestations, near dredging operations and where tidal flushing is poor, and suggest avoiding shallow water, turbid water, and darkness, when benthic (bottom-dwelling) organisms may be up in the water column. The guidelines provide advice on the timely and routine cleaning of sediment from ballast tanks and include recommendations to avoid unnecessary discharge of ballast water, to retain or minimize release of improperly exchanged ballast and, where applicable, to discharge to appropriate reception facilities. Some guidelines also address anchor-chain washing and removal of hull fouling. The guidelines also recommend maintaining ship ballast water management records and plans and providing training in ballast water and sediment management for ships' personnel.

Making such ballast water management practices mandatory for all ships capable of carrying ballast water, including NOBOBs, into the Great Lakes - St. Lawrence River basin could greatly reduce, though not eliminate, the threat of introduction of alien invasive species in the Great Lakes. Along these lines, agencies have made some progress. For example, the St. Lawrence Seaway Development Corporation (SLSDC) in the U.S. and the St. Lawrence Seaway Management Corporation (SLSMC) of Canada jointly administer the Seaway Regulations and Rules. The SLSDC, in agreement with the SLSMC, has amended its regulations to require compliance with Great Lakes shipping industry codes for ballast water management practices for a ship to gain permission to transit the seaway.¹⁵ While this step is encouraging, the amendments appear to lack sufficient means to measure compliance and support enforcement. The SLSDC and SLSMC have indicated they will assess the effectiveness of this action after the 2002 seaway navigation season.

Improved mandatory ballast water management practices could use procedures approved by the Coast Guard, or a classification society authorized to act on its behalf, to ensure that the best practices are incorporated for each vessel's particular operational constraints. Owners and operators of ships could also be required to address other possible pathways for unintentional transfer of alien invasive species not connected to ballast systems, such as hull fouling, biofilms and anchor chains. And customers for shipping could be encouraged to contract with owners and operators of shipping lines that apply best management practices.