Why is the water dropping in the Great Lakes?

If you walk along the shores of any of the Great Lakes these days, you notice that the water levels have dropped significantly.

This morning I was down at the Lake Ontario waterfront and saw for myself that the water line is about a foot-and-a-half lower than last year. Moorings and pilings are getting higher and drier.

Scientists and environmentalists are not sure what's causing this drop in water levels. It may be a change in rainfall patterns, it may be related to global warming or, as others suggest, it may be related to human activity, like dredging and industrialization in the Great Lakes basin.

Whatever the cause, it's disturbing. We can only hope it's temporary. According to the U.S. National Oceanic and Atmospheric Administration, between 1998 and 2000 the levels of Lake Michigan and Lake Huron fell at the fastest pace ever recorded and the situation is similar to the drop that occurred during the Great Depression in the 1930s.

Earlier this year, residents on both sides of the Canadian and U.S. border pushed for an investigation into whether erosion in the St. Clair River, between Lakes Michigan and Huron, was causing a big drop in the water level in Lake Huron. The Georgian Bay Association wondered whether dredging had caused erosion significant enough to cause nine billion liters of water per day to drain from Lake Huron into the lower Great Lakes and out into the ocean.

A few weeks ago, the International Joint Commission, which provides information to both the American and Canadian governments, concluded that there's no evidence that erosion is the cause. The findings are still preliminary, but video pictures from the bottom of the channel seem to indicate a stable rock bed. However, many questions remain to be answered and more studies, over longer periods of time, will need to be done.

We've seen lots of related stories in recent months. Residents of Atlanta went through a difficult summer, as a prolonged drought in the Southeast led to significantly reduced water levels in Lake Lanier, a primary reservoir for the city.

Let's hope science provides some clues to the cause of these changes. It really would be a sign of trouble, I think, if the Great Lakes were to continue drying up.

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