FINAL REPORT - International Joint Commission

Water Diversions
There are presently five diversions on the Great Lakes: the Long Lac and Ogoki diversions into Lake Superior,
amounting to 150 m3/s (5,300 cfs), the Chicago Sanitary and Ship Canal diversion from Lake Michigan,
amounting to 91 m3/s (3,200 cfs), the Welland Canal passing on average 241 m3/s (8,500 cfs) from Lake
Erie into Lake Ontario, and the New York State Barge Canal passing on average 28 m3/s (1,000 cfs) from the
Niagara River to Lake Ontario. The Welland and New York State Barge canals do not divert water into or out
of the Great Lakes, but rather provide navigation channels around Niagara Falls. Man-made diversions play
a minor role in the balancing of Great Lakes water levels when compared with natural forces. The cumulative
impacts of all five diversions have raised Lake Ontario levels by less than 0.4 cm (less than 1 inch).
FINAL REPORT
New diversions of Great Lakes water are restricted by the Canadian Boundary Waters Treaty Act, the
Great Lakes Charter (signed in 1985) and the supplementary implementing agreements of the Great Lakes
Charter: Annex 2001 (signed December 14, 2005). Consideration of any new diversions and their impacts
on the levels of Lake Ontario are beyond the scope of this Study.
Water Quality Concerns
Water quality is a major issue, but it was beyond the scope of this Study since it is only marginally affected
by water levels. The depth of water in near-shore areas around Lake Ontario and in shallow areas within
and along the St. Lawrence River has an impact on the growth of algae and concentration of toxins. But
algae and toxins result from other factors that would prevail regardless of water levels. This is appropriately
addressed by the Great Lakes Water Quality Agreement between Canada and the United States, which
strives “to restore and maintain the chemical, physical and biological integrity of the water of the Great
Lakes Basin Ecosystem.”
Options for Managing Lake Ontario and St. Lawrence River Water Levels and Flows
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