IUGLSB Says No Action Needed On St. Clair River Water Loss

Dec 15: Since 2007, a binational team of experts, with extensive public input, has been investigating whether there are ongoing changes in the St. Clair River that might be affecting water levels in the upper Great Lakes [See WIMS 5/5/09]. The International Upper Great Lakes Study Board (IUGLSB), of the International Joint Commission (IJC), released its final report and found that: (1) There has been no significant erosion of the channel in the upper reach of the St. Clair River bed since at least 2000. (2) Based on 15 different analyses, an increase in the river’s conveyance capacity accounts for 7 to 14 cm (2.8 to 5.5 inches) of the decline in head difference between Lake Michigan‐Huron and Lake Erie from 1963 to 2006; however, this change is not ongoing and there has been a slight decrease in conveyance capacity since 2000. (3) Climate is the main driver of lake level relationships over time and accounts for 9 to 17 cm (3.5 to 6.7 inches) of the decline in head difference.

In particular, hydroclimatic change contributed to a substantial decline in net water supplies to Lake Michigan‐Huron in the most recent decade. Overall, the Study Board also found that the difference in water levels between Lake Michigan‐Huron and Lake Erie (head difference) declined on average by about 23 cm (9 inches) between 1963 and 2006. They also found that shifts in the earth’s crust as it continues to adjust to the retreat of glaciers account for 4 to 5 cm (1.6 to 2 inches) of the decline in head difference with the apparent resulting decrease in water levels being more pronounced in the Georgian Bay region of eastern Lake Huron.

Given that the change in conveyance capacity is not ongoing, is small relative to the degree of scientific uncertainty associated with the various analyses and data measurements and appears to be decreasing, the Study Board did not recommend remedial measures in the St. Clair River at this time.

The organization Georgian Bay Forever (GBF), a Canadian environmental charity which has been the leading voice in raising concerns about the impact of low water levels on the unique ecology of Georgian Bay said the IUGLSB "missed a historic opportunity to recommend environmentally sound solutions to the serious water levels situation facing the middle Great Lakes." The group is now calling on IJC Commissioners to reconsider and overrule the 'do nothing' recommendations" of the IUGLSB.

GBF said, "The main recommendation of the IUGLSB final report -- that no remedial measures are needed to slow down the outflow of the middle Great Lakes -- ignores the consequence of the continuing and irretrievable loss of water from the Lakes Huron/Michigan and Georgian Bay." They indicated that, "The IUGLSB has previously conceded up to six billion more gallons (almost 23 billion litres) of water per day are flowing out of the Middle Lakes compared to 1971, but have decided the amount is too insignificant to justify any action."

Access a release from IUGLSB (click here). Access links to the complete scientific report, a summary for the public, 34 scientific reports that form the foundation for the main report and additional information (click here). Access a release from GBF (click here). Access the GBF website for links to a critique of the report and extensive background information (click here).