In September, the U.S. Congress revised and ultimately upheld a policy that will continue to allow freighters to dump traces of cargo such as iron ore, wood chips and limestone (a process called “cargo sweeping”) into the Great Lakes.

Cargo sweeping is illegal in U.S. waters, though carriers on the Great Lakes have operated under an Interim Enforcement Policy since 1993, which allows for “the incidental discharge of non-toxic, non-hazardous dry cargo residues (DCR).” The policy was set to expire on September 30, 2008, following a two-year environmental impact assessment.

According to an August report from the U.S. Coast Guard (USCG) and the Environmental Protection Agency, freighters dump nearly 500 tonnes of waste into the Great Lakes water system annually. Although the USCG states that the environmental impacts of dumping this amount of residue into the Great Lakes are negligible, there are major concerns in conservation circles about the long-term effects of such practices. Much of the detritus – especially iron ore and taconite – contain toxic metals such as mercury that have the potential to contaminate wildlife as well as people.

“Legally, it is difficult to prove that one act of cargo sweeping or one act of discharging ballast water is responsible for the decline of the Great Lakes,” says Mark Mattson, president of Lake Ontario Waterkeeper. “Collectively, these acts are ravaging the entire ecosystem.”

September’s revisions include interim rules that will require ships to keep records of DCR discharges and use control measures designed to minimize the amount of residue entering the Great Lakes. New prohibitions also mean that sweeping DCR into certain protected areas, which was previously permitted, is now illegal.

“As long as the U.S. Coast Guard sanctions the practice of sweeping waste into the Great Lakes, we cannot be confident that our lakes are being protected,” says Mattson. “The USCG’s interim rule is out of step with existing environmental protections for the lakes in the United States and Canada, and internationally.”

The USCG is asking for public comments on the need for additional restrictions that can be added to future cargo sweeping policy. Comments can be submitted on the U.S. government’s regulations website ( The comment period ends January 15, 2009.

by Jim MacInnis