Chemical limnology of Georgian Bay and the North Channel between 1974 and 1980

Abstract

Intensive surveys of Georgian Bay and the North Channel were done in 1974 and 1980. This paper reviews the main findings of the surveys and describes the main factors that determine the chemistry of the two water bodies. Georgian Bay is oligotrophic. Its chemistry is determined chiefly by natural phenomena, specifically the geology of the drainage basin and the river runoff in the spring, and by exchange with Lake Huron and the North Channel. Localized eutrophication is found in the bays along the southern shore. The chemistry of the North Channel is determined by its very short residence time — about two years — caused by the large inflow from St. Mary’s River. The water quality in the river reflects that of Lake Superior and the inputs of nutrients and contaminants from Sault Ste. Maire. Because of the short flushing time, the Channel remains oligotrophic despite the large loadings of phosphorus.