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Great Lakes Article:

River erosion cutting into Great Lakes' water levels, report finds
By Hugh McDiarmid Jr.
Knight Ridder Newspapers
Published in the Kansas City Star January 24th, 2005


DETROIT - (KRT) - Lakes Michigan and Huron have permanently lost a foot of water because of erosion in the St. Clair River caused by dredging and other man-made meddling, according to a study released Monday.

The decline will continue for the foreseeable future, it warns, battering boaters, marinas, property owners and the shipping industry struggling with water levels at the bottom of historical cycles.

The low water was troublesome, but temporary, experts had assured those struggling with dried-out boat canals.

Now, they're not so sure.

The reason: Erosion created gouges in the river bottom up to 19 feet deep between 1970 and 2000, enlarging the bottleneck at the bottom of Lake Huron where water drains into the lower Great Lakes and Niagara Falls.

"It's like a drain hole at the bottom of a bathtub," said Rob Nairn, a principal with W.F. Baird & Associates Coastal Engineers of Toronto, which conducted the study for the Georgian Bay Association, a civic organization representing about 4,200 Canadian families who live on Georgian Bay islands and shores. "The drain hole is getting bigger, and the water is going out faster. It's something very alarming that no one has talked about or reported until now."

Jim Weakley, president of the Lake Carriers' Association, which represents domestic shipping companies, said he had not seen the report Monday, but that a solution must protect both commerce and the environment: "Any loss of Great Lakes water is of concern for us. Each additional inch allows between 250 and 270 tons of cargo" on a larger freighter, he said.

Experts agree that dredging to deepen the St. Clair River for commercial ships reduced the volume of water in Huron and Michigan. Three such projects, the last one completed in 1962, account for a 19-inch reduction in lake levels, Nairn said.

That was believed to be a one-time drop. Until now.

Monday's report found Lakes Michigan and Huron - considered one body of water because they are connected at the Straits of Mackinac - have lost an additional 12 inches since 1970 because of erosion that has gone undetected since the 1962 dredging.

All told, the dredging and erosion has accounted for a water loss from the lakes equivalent to 28 Lake St. Clairs, according to the Baird report.

Because the extra water moves so quickly through Lake St. Clair, the Detroit River and Lake Erie on its way over Niagara Falls, it has not raised the levels of those waters appreciably, Nairn said.

A modest resurgence in Great Lakes water levels during the past two years is part of a natural cycle, but doesn't mask the fact that the Huron/Michigan waters are still a foot below where they would be without the erosion, Nairn said.

And the problem can't be explained by natural forces, he said. Geologists say erosion in the St. Clair River basin stopped between 2,000 and 3,000 years ago. But it began again in the 1900s because of man-made factors including:

Dredging of the channel to 27 feet deep to accommodate ships.

Erosion at the sites of sand mining that took place in the river in early part of the 1900s.

Erosion control structures protecting beaches on lower Lake Huron that deprive the St. Clair River of sediment that normally would have washed into it and filled holes in the river bottom.

The lakes' water loss went unnoticed because it was masked by high water levels of the 1970s and 1980s, the report suggests. But when Lake Huron receded in the 1990s and early 2000s, residents of the archipelago of Canadian islands in Georgian Bay suspected more than just the usual 30-year, high-to-low water levels cycles were in play.

"In recent years, we have had a significant number of wetlands dry up on Georgian Bay, and the aquatic life forced out onto steep granite shorelines," said Mary Muter, the Georgian baykeeper who monitors the area's natural resources.

They commissioned the study at a cost of about $163,000 to find out.

The results have alarmed scientists and policy-makers across the region.

"We take it very seriously," said Dennis Schornack, U.S. chair of the International Joint Commission, which oversees boundary waters linking the United States and Canada. "It's definitely of concern and the kind of thing that is supposed to be part of an Upper Great Lakes study that has not been funded yet by Congress."

Schornack said the potential for dredging-related trouble was apparent as early as 1921, when a deepening of the St. Clair River was approved by the IJC, with one condition: that weirs - underwater barriers - be installed to slow the velocity of water that would be increased by the channel deepening.

Those barriers were never built, said Schornack.

Underwater barriers or other methods to combat the erosion need to be considered quickly, Nairn and a coalition of environmental groups said Monday. The report did not suggest solutions, however.

The data also must be part of an ongoing bi national study of the future of commercial navigation on the Great Lakes, said the environmental groups.

"The Great Lakes are more than simply a navigation corridor, and the time has come for the management of the lakes to reflect that," said Jennifer Nalbone, habitat and biodiversity coordinator for Great Lakes United, a bi national lakes advocacy group.

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