Water Levels in 3 Great Lakes Dip Far Below Normal

Water levels in the three upper Great Lakes are wavering far below normal, and experts expect Lake Superior, the northernmost lake, to reach a record low in the next two months, according to data from the international bodies that monitor the Great Lakes, the world’s largest freshwater reservoir.

Although the cause of the falling levels is in dispute, the effects in Lakes Michigan and Huron are visible everywhere. Ship channels are overdue for dredging. Wetlands in some areas like Georgian Bay, east of Lake Huron in Ontario, have dried up, leaving fish and birds without accustomed places to reproduce.

Beaches around Saginaw Bay in Michigan have reverted to marshes as shorefront reverts to wetlands. One-third of the Michigan boat ramps are unusable.

Although the drop in levels in all three lakes is variously ascribed to climate change or new rainfall patterns, evidence is growing that people caused some losses in Lakes Huron and Michigan.

Gravel mining early in the 20th century by private companies and dredging by the Army Corps of Engineers, particularly in the mid-1960s, may have widened and deepened the St. Clair River, through which those two lakes drain into Lake Erie.

The flow may be eroding the riverbed. The erosion may in turn result in increased outflow, more than can be replenished by rain or snowmelt, according to a study by a group of Canadian coastal engineers.

Data being released this week by a group of Canadian homeowners, supplementing an engineering study from 2005 by W. F. Baird and Associates, a Canadian business, indicates that the outflow is undiminished and may be significantly greater than earlier estimates.
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