Great Lakes at Record Low Water Levels
In August, Lake Superior, the largest of the five Great Lakes, set a record for low water levels over the last century, and is heading for a record in September. Water flow out of the lake is also down 30% over averages. Lakes Michigan and Huron are at the level of Chart Datum, below their all-time average levels for this time of year. Lakes St. Clair, Erie and Ontario are below their all-time average levels for this time of year, but above Datum. The water level at Montreal Harbour is below average for this time of year and below Datum. (Kingston, Ontario levels are the lowest we've recorded in our log in 21 years - and still dropping.)
The Georgian Bay Association is advancing its 2005 theory that excessive dredging near Sarnia and gravel mining many years ago have been the equivalent of pulling a drain plug, now causing loss of 10 billion litres a day, three times more than previously thought.
The five Great Lakes form the world's largest interconnected body of fresh water, containing one-fifth of all the fresh water on Earth. 99% of the lake waters are considered a legacy of the last ice age. Only about 1% is replenished each year through precipitation, which must offset evaporation and water flowing through the St. Lawrence River into the Atlantic Ocean.
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