The Lake Carriers' Association says the measures will reduce the threat of viral hemorrhagic septicemia entering the lake or spreading there. The virus has been found in the other Great Lakes and in some inland lakes.
The group says freighters will try to take on ballast water in deep water away from shore and will re-circulate ballast water in their tanks to chop up any fish it may contain.
Wisconsin state fisheries official Mike Staggs says the measures could help but says ballast water still could contribute to the spread of disease and exotic species.
