Scientists have seen it in Lake Erie and the bay of Green Bay. But the last place they expected to find plumes of toxic algae is in Lake Superior.
That's because Superior is cold, deep, and mostly surrounded by forest, not agriculture. Runoff from agriculture fuels toxic algae.
But sporadic blooms have appeared in Lake Superior, mostly along its southern shore. This summer, scientists are trying to figure out why, and whether science can help control what so far has only been an occasional nuisance before it becomes a bigger problem.
