Regulators in the United States have launched a formal investigation into Canada's plan to change the rules that govern shipping on the Great Lakes.
U.S.-based shippers say proposed new Canadian standards for the use and release of ballast water are unfair, overly costly and designed to drive them out of the business of cross-border shipping on the lakes.
The measures, proposed by Transport Canada to limit the release of invasive organisms, would require new water treatment systems on all vessels operating in Canadian waters, and impose stringent new performance standards.
The U.S. Lake Carriers' Association, which petitioned the Federal Maritime Commission for an investigation, says it would cost the industry C$1.1 billion to meet the new standards.
The trade association says Transport Canada has estimated the cost to their Canadian counterparts to be just $632 million.
Canada proposed the new rules last year in accordance with an international maritime treaty the U.S. hasn't signed.