U.S. Water News Online
TORONTO, Can. -- 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
Water is permanently being sucked from Lakes Huron and Michigan
because of ongoing erosion caused by dredging and other human
activities in the St. Clair River -- the drain that funnels water out
of the lakes -- according to a study.
If the data are accurate, the lakes may have already lost 12
inches of water in addition to natural lake level fluctuations. The
data would also help explain the low water levels that have plagued
boaters and beachfront landowners during the last few years.
Policy makers may need to explore ways to slow the outflow to
protect the environment as well as Great Lakes shipping interests
that depend on deep river channels.
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 made 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 that
represents domestic shipping companies, said he had not seen the
report, 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.
The 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
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.
The residents commissioned the study at a cost of about $163,000
to find out.
The results have alarmed scientists and policy makers across the
"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. The report did not suggest solutions.
The data also must be part of an ongoing binational study of the
future of commercial navigation on the Great Lakes, said the
"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 binational lakes advocacy group.
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