Who causes more pollution to lake ontario the americans or the canadians?

I'd say the Americans (USA type Americans that is) are the worst. See these three quotes from the noted articles for substantiation of this. Detroit was long regarded as the worst offender for sending sewage into the Great Lakes. From 2006 - Milwaukee has long been painted by environmentalists as a villain for its chronic sewage spills into Lake Michigan, but a report released Wednesday by a Canadian conservation group shows the city is far from the worst polluter in the Great Lakes. One of the biggest pollution threats of the moment is a proposed U.S. Army Corps of Engineers plan to boost dredging operations for harbors and shipping channels everywhere from Ohio’s Toledo Harbor to Detroit’s River Rouge to the port at Gary, Indiana, increasing the amount of dredged silt by 167 million cubic yards yearly.  more