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We’ve posted before in these pages news about the Great Lakes’ own drought. Of course it isn’t the same as the drought in the South East which is putting the drinking water for Atlanta in peril but it is a decrease in water levels nonetheless.

Water levels in the Great Lakes are falling; Lake Ontario, for example, is about seven inches below where it was a year ago. And for every inch of water that the lakes lose, the ships that ferry bulk materials across them must lighten their loads by 270 tons — or 540,000 pounds — or risk running aground, according to the Lake Carriers’ Association, a trade group for United States-flag cargo companies.

The water levels in all five Great Lakes — Superior, Michigan, Huron, Erie and Ontario — are below long-term averages and are likely to stay that way until at least March, according to the Army Corps of Engineers. (The same is true at Lake St. Clair, which straddles the border between the state of Michigan and the province of Ontario and is between Lake Huron and Lake Erie; it is not considered one of the Great Lakes, although it is part of the Great Lakes system.)

Most environmental researchers say that low precipitation, mild winters and high evaporation, due largely to a lack of heavy ice covers to shield cold lake waters from the warmer air above, are depleting the lakes. The Great Lakes follow a natural cycle, their levels rising in the spring, peaking in the summer and reaching a low in the winter, as the evaporation rate rises.

In the past two years, evaporation has been higher than average, and not enough rain and snow have fallen in the upper lakes — Superior, Michigan and Huron — which supply water to the lower lakes, to restore the system to its normal levels…

Great Lakes Shrink