Falling lake levels in the Great Lakes, especially Lake Huron and Lake Michigan, have generated considerable controversy and scientific debate. In 2004, a study by the internationally respected coastal consulting engineering firm Baird & Associates found that decades of dredging in the St. Clair River, shoreline alterations, and sand and gravel mining have led to an increased conveyance that draws more water from Lakes Michigan and Huron into the lower lakes (Erie and Ontario) and out the St. Lawrence River to the Atlantic Ocean. The Baird & Associates study was commissioned and paid for by the GBA (Georgian Bay Association) Foundation, with advocacy work led by the Georgian Baykeeper. In response to the work of the GBA Foundation and Georgian Bay advocates (and resulting political pressure) the International Joint Commission agreed to conduct a public, scientific study to determine why lake levels are falling.
The result of the IJC International Upper Great Lakes Study is a draft report “Impacts on Upper Great Lakes Water Levels: St. Clair River” released for public comment on May 1. The IJC draft report basically concludes that Lakes Michigan-Huron (which are really one water body) dropped more than 9 inches (23 cm) compared to Lake Erie between 1962 (the time of the last major dredging in the St. Clair River) and 2006. The IJC draft report blames the falling lake levels on three primary factors:
Changes in climate, accounting for most of the decline in the last ten years.
A relatively dramatic and rapid change in conveyance in the St. Clair River in the mid-1980s, possibly resulting from a major ice jam.
“Glacial isostatic adjustment,” which is the rebounding of the earth’s crust after the melting of the glaciers about 10,000 years ago (the draft report quantifies this as a relatively minor factor).
According to the IJC draft report, these three factors, and not the dredging of the St. Clair River by the U.S. Army Corps of Engineers or other human physical disturbances, account for the declining lake levels. The draft report concludes that there has been no ongoing erosion along the length of the St. Clair River bed since at least 2000, and thus remedial measures on the St. Clair River are not warranted at this time.
While many of us had hoped that the IJC’s work would provide a definitive answer to the question of falling lake levels to guide policy solutions, it may have created more controversy. As reported by Dan Egan of the Milwaukee Journal Sentinel, the IJC draft report has not yet been peer reviewed, despite previous claims by the study co-chairman. So the IJC has basically put the report and policy recommendations out for public comment without the benefit of scientific peer review. This was done to speed things along in response to public and political pressure, according to the IJC.
I appreciate the IJC’s responsiveness to growing concern over falling lake levels, but taking public comment before the study has been peer reviewed is putting the cart before the horse. As a member of the public, I want to trust the scientific work of the IJC (and that trust depends on peer review), then offer my input on what the policy response should be. Instead, the public won’t have the results of the peer review until the public comment period is almost over. There’s a simple fix to this problem – extend the public comment period for 60 days after the peer review is completed (assuming the peer review approves the draft report’s methodology and conclusions). Then we can have an informed and public debate about how to best protect Great Lakes levels from climate change, dredging, and other human impacts.