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North America’s Great Lakes are the cleanest they have been in 50 years,
according to a report put out last week by the International Joint Commission,
which oversees transborder issues between Canada and the US. Although PCBs,
mercury, dioxins and pesticides are still found in the lakes, their average
levels have reduced by half or more since 1976. Four species of
fish—sturgeon, lake trout, lake herring and deep-water sculpin—have
in the past two years returned to the lakes after long absences.