No Action Necessary Now For St. Clair River Erosion

May 1: The International Upper Great Lakes Study (IUGLS) issued a draft report nearly one year ahead of its original schedule, indicating that erosion of the St. Clair River is not ongoing and recommended that “remedial measures not be undertaken at this time.” The report -- Impacts on Upper Great Lakes Water Levels: St. Clair River -- is the product of intense effort by a 10 member binational Study Board of experts and public members, who commissioned 42 research projects that engaged over 100 scientists. Fourteen public meetings have been scheduled throughout the region where residents can learn about the findings and provide comments.

The Study Board was appointed by the International Joint Commission (IJC) to determine whether the conveyance capacity of the St. Clair River has changed, to assess if there is ongoing erosion in the river bed and to identify other factors that may be affecting water levels. Specifically, the independent panel examined the change in head drop (or difference in water levels) between Lake Huron and Lake Erie, estimating the decline to be 23 centimeters (cm) or 9 inches (in) between 1962 and 2006. After an exhaustive effort to collect and verify historical data, conduct new research and analyze results, three key factors were identified as contributing to the decline: A change in the conveyance of the St. Clair River; Changes in climatic patterns; and Glacial isostatic adjustment.

The report emphasized that, “Climate is the main driver of the lake level relationships between lakes and over time. There has been a persistent decline in net total supply of water to Lake Superior and Lake Michigan-Huron over the past two decades that has resulted in declining lake levels and a change in the relationship to Lake Erie.” The Study Board also recommended that, “The need for mitigative measures in the St. Clair River continues to be examined as part of the continuing Study that will include a comprehensive assessment of the future effects of climate change on water supplies in the upper Great Lakes basin on Lake Superior regulation.”

Access a release from the IUGLS (click here). Access an overview and summary of the report (click here). Access links to the complete report, upcoming public meetings, commenting procedures and more (click here).