By IUGLS
Nov 10, 2011
Photo from Lake Superior. Credit: Randen Pedersen
According to the latest data from Environment Canada, the October water supply to the Lake Superior basin was below average for the third month in a row. On the Lake Michigan-Huron basin, however, the basin supply was well above average for October, up from below-average levels in July and September. Supplies also were above average for Lakes Erie and Ontario in October, for the third consecutive month.
Regulated outflows from Superior to the lower lakes also were below average for October. Still, the below-average supplies that Superior received caused the lake’s level to drop by 5 centimeters (about 2 inches), about a centimeter more than is average for the month. Declines on Michigan-Huron levels were below average, along with declines in Lake Erie and Lake Ontario levels.
As of this writing, the levels of Superior and Michigan-Huron are below their long-term averages (1918-2010), while Erie and Ontario are above their averages.
However, the levels of all the Great Lakes are higher than at this time a year ago. The basin, as a whole, received about 12 percent more precipitation than average during October, according to preliminary data from Environment Canada.
All of the lakes are now in a period of seasonal decline. During November, Superior and Michigan-Huron are each projected to drop 2 inches (about 5 centimeters) from their current levels, based on forecasts from the U.S. Army Corps of Engineers. The water levels of Erie and Ontario are expected to decline by 4 inches during the next month.
The regulated outflow from Superior for November is scheduled to remain unchanged from October, at 1,560 cubic meters per second, Environment Canada officials say. That’s 29 percent below the long-term average outflow for the month.