Changes in Level of Great Lakes Natural, Not Manmade

Published August 1, 2009

The International Joint Commission, which addresses issues concerning waters that border the U.S. and Canada, has released a report explaining why Upper Great Lakes water levels recently have been lower, relative to Lower Great Lakes water levels, than they’ve been in the past.

The report puts to rest environmentalist claims that human activity has been responsible for the shift.

Three Factors

The May 1 report, Impacts on Upper Great Lakes Water Levels: St. Clair River, found three primary reasons for the recent disparity in Great Lakes levels.

First, the report observed, a major ice jam in the spring of 1984 gouged the bed of the St. Clair River, increasing the water discharge from Lake Huron into the Lower Great Lakes.

Second, regional weather patterns reduced rainfall in the Upper Great Lakes watershed relative to the Lower Great Lakes watershed.

Finally, the continuing rebound in the Earth’s crust as it recovers from the last ice age also contributed to the changing relationship between Great Lakes water levels.

No Remediation Needed

The report concluded remedial measures need not be taken to address the water level differentials.

That conclusion is not sitting well with GBA Foundation, a Canadian environmental group that funded its own study in 2004 putting the blame on human activity.

Said GBA Foundation President Roy Schatz in a May 1 press statement, “The fact that [the report] completely dismisses such an enormous increase in outflow and recommends that nothing be done about it is very disturbing.”

For years many environmental activists blamed the U.S. Army Corps of Engineers and dredging work the agency preformed on the St. Clair River bed in the early 1960s, work designed to broaden and deepen the channel to allow better navigation. The work, they allege, created an excessively large “drain hole.”

The joint commission’s report, however, finds the dredging and subsequent drain hole most likely did not cause a significant amount of water to drain away.

While some increased flow from Lake Huron through the St. Clair River occurred in recent decades, mainly after the April 1984 ice jam, the report concludes the river bed seems to be naturally stabilizing.

Limited Effect of Regulation

Although the study essentially cleared the St. Clair River as a cause for future concern and did not recommend remedial measures, John Nevin, spokesman for the agency that sponsored the study, does not rule out future efforts to restore the prior water level relationship between the Upper and Lower Great Lakes.

“Further review of the climate, in the second part of the study, may be a reason to consider a mitigative step to putting a structure in the river,” said Nevin.

Lakes Superior and Ontario are already regulated with power dams and control gates, but the effectiveness of that kind of regulation with respect to Lakes Michigan and Huron is doubtful, Nevin said, considering the combined size of the latter two lakes.

“Science can only take you so far, then we need the public to say if they want some regulation or more or less leave it to Mother Nature,” said Nevin.

Penny Rodriguez ([email protected]) writes from Parrish, Florida.

For more information …

“Impacts on Upper Great Lakes Water Levels: St. Clair River, Report 1 of the International Upper Great Lakes Study”: