14 August 2007Felicity Barringer
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.
If the new estimates are correct, 2.5 billion gallons a year are being lost through the expanded parts of the St. Clair, roughly the equivalent of the amount diverted annually for Chicago’s needs.
Robert B. Nairn, a coastal and river engineer who is a principal at Baird, said in an interview Monday, “I was surprised that something of this magnitude could be happening.”
Although Mr. Nairn said the man-made changes were consequential, he was cautious about speculating whether they had played a greater role in the water loss than other factors, like climate change.
“I think we found that all of those contributed to some degree,” he said. “The big question that remains is how much is each contributing.”
Those questions are a central focus of a new study begun under the auspices of the International Joint Commission, a binational group whose members are appointed by the governments in Washington and Ottawa to monitor the boundaries and water quality of the Great Lakes.
Eugene Stakhiv, an official of the Army Corps of Engineers on loan to the commission, said the Baird group had raised significant questions.
“They raised concerns and came to conclusions that make sense within the information and models they used,” Mr. Stakhiv said. “But I think there are still many uncertainties.”
That the water levels in the upper lakes are falling is certain. Data from the corps’s Web site indicates that Lake Superior has almost reached its record low, set in 1926.
Roger Gauthier, a project manager at the Great Lakes Commission, an intergovernmental body representing eight states and two Canadian provinces, said water levels in Lakes Michigan and Huron had dropped three feet since 1999 and were about seven inches above the record low set in 1964.
The persistence of low water in Lakes Huron and Michigan has been out of keeping with the larger cycles of high and low water in the basin.
The level of Lakes St. Clair and Erie, more southerly lakes, has been slightly above average. These lakes receive the Huron and Michigan outflow. Intake of abnormally high amounts of water could raise their levels. But so could unusually high rainfalls.
Mr. Stakhiv said he would not prejudge the cause of these changing water levels before new measurements were taken.
But the Georgian Bay Association, the homeowners’ group that hired Baird, says it believes that its study has identified the problem, and its members are impatient for a solution.
“We obviously believe that the river is eroding,” said Bill Bialkowski, a homeowner who is an engineer and took the new measurements. “It would be nice to stabilize it where it’s occurring.”
Representative Candice S. Miller, Republican of Michigan’s 10th District, which includes shoreline of Lakes Huron and St. Clair, said she had tried, unsuccessfully, to obtain a $3 million to $5 million Congressional appropriation to pay for an Army Corps of Engineers study of the crucial waterways.
If the Baird hypothesis is correct, Ms. Miller said, “you’re diverting millions of gallons into the Atlantic Ocean.”
http://www.nytimes.com/2007/08/14/us/14lakes.html?_r=3&ref=us&oref=slogin&oref=slogin&oref=slogin
