U.S.-Canada Panel finds that St. Clair River is Stable

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U.S.-Canada Panel finds that St. Clair River is Stable

Board sees no need for Remedial Measures

 

 

January 4, 2010 / www.great-lakes.org

 

 

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. In a report released December 15, 2009, the International Upper Great Lakes Study Board found there has been no significant erosion of the channel in the upper reach of the St. Clair River bed since at least 2000.

 

 

Other findings included:

 

►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.

 

►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 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.

 

►As directed in its mandate, the Study Board also reviewed past proposed remedial works and new innovative approaches to modifying flows in the St. Clair River and identified a range of options that might be employed if remediation were deemed necessary. The Study recognizes that there have been a number of dredging projects in the past and the governments made commitments for remediation. The implications of these past dredging projects are beyond the scope of the Study. The complete scientific report and a summary for the public are posted at: www.iugls.org. The 34 scientific reports that form the foundation for the main report are also available online.

 

 

Key Recommendations

 

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 Board also recommended that the governments of Canada and the U.S. undertake cooperative efforts to improve the monitoring and analysis of Great Lakes water supplies and connecting channel flows.

 

 

Independent Peer Review

 

Throughout the Study, both methodological plans and technical work products including key chapters and the full draft report were reviewed by independent experts chosen by the American Society of Civil Engineers (ASCE Environmental and Water Resources Institute) and the Canadian Water Resources Association. These expert reviewers have given generally positive ratings and provided many constructive recommendations that have resulted in improvements to the final report, ranging from the need for additional analysis to the need to better quantify scientific uncertainty. All reviews and Study Board responses are available at the ASCE website, http://content.ewrinstitute.org/committees/IUGLS.cfm

 

 

Public Input

 

A binational Public Interest Advisory Group (PIAG) with expertise from a wide range of interests has provided advice to the Study Board on public involvement and outreach issues. The U.S. and Canadian co-chairs of PIAG both serve on the Study Board, providing direct involvement by the public in key decisions. Since 2007, the Study has held 34 public meetings hosted by PIAG members throughout the upper Great Lakes basin, including 17 meetings during a 90-day consultation period following release of a draft report on May 1, 2009.

 

All public comments received by the August 1 deadline and Study Board responses are posted on the Study website as well as a detailed report on PIAG activities over the past two years, including a synthesis of the public views provided during the consultation. Generally, it appeared that the public found that Study outcomes were acceptable with respect to the mandate, resulted from an open and unbiased process and reflected sound science. However, it should be noted that many commenters with interests in Georgian Bay disagreed with the Study’s recommendation against remediation. The International Joint Commission has announced it will hold public hearings regarding the report in 2010, allowing the public ample time to review the report, related technical studies and the independent peer reviews.

 

The International Joint Commission is inviting the public to submit comments on the final report until April 9, 2010. The IJC will hold public hearings during this period at times and locations to be announced early in the new year.

 

 

What’s next?

 

The examination of the St. Clair River is part of a broader evaluation of the regulation of Lake Superior outflows that is expected to produce recommendations in 2012 regarding improvements to the control orders for the international compensating works and power dams on the St. Marys River in Sault Ste. Marie. The Study Board also recommends that this phase of the Study examine whether mitigative measures in the St. Clair River might be necessary based on its assessment of the potential future impacts of climate change on upper Great Lakes levels.