Lake Erie is the most productive of the Great Lakes. Located along the southern fringe of the Precambrian Shield of North America, Lake Erie has been ecologically degraded by a variety of anthropogenic stressors including nutrient loading; extensive deforestation of its watershed that caused severe siltation and other effects; vigorous commercial fishing; and pollution by toxic chemicals.

The watershed of Lake Erie is much more agricultural and urban in character than are those of the other Great Lakes. Consequently, the dominant sources of phosphorus (the most important nutrient causing eutrophication) to Lake Erie are agricultural runoff and municipal point sources. The total input of phosphorus to Lake Erie (standardized to watershed area) is about l.3 times larger than to Lake Ontario and more than five times larger than to the other Great Lakes.

Because of its large loading rates and concentrations of nutrients, Lake Erie is...