International Upper Great Lakes Study:
Lake Huron-Michigan levels falling more steadily than those
on Lake Erie
By WILLIAM HRYB
March 15, 2010
Water, water every where ... but not enough in the right places, according to some residents along the upper Great Lakes Basin.
It’s no secret that water levels in Lake Superior, Lake Michigan and Lake Huron, including Georgian Bay, have fallen more steadily over the past decade than those on Lake Erie. Nearly 100 Canadian and American scientists and engineers began studying the reasons three years ago. Their conclusions are part of the International Upper Great Lakes Study (IUGLS), which recently generated a report entitled Impacts on Upper Great Lakes Water Levels: St. Clair River.
With an estimated budget of $4 million, the IUGLS worked with independent peer reviewers and the public to answer three basic questions posed by the International Joint Commission (IJC) regarding the St. Clair River that runs between Lake Huron and Lake Erie:
• Has the conveyance or water-carrying capacity of the St. Clair River changed, and if so, why?
• What effect could an altered flow have on water levels in the upper Great Lakes?
• What actions, if any, should be taken by governments to remedy concerns about low water levels?
The report was published eight months after the release of a draft and a 90-day public comment period. Seventeen public meetings were held throughout communities in the Great Lakes Basin.
After an exhaustive examination, the IUGLS points a finger at climate change and shifting weather patterns for changing water supplies and water levels. However, the report also notes that physical changes in the St. Clair River, possibly associated with high-water levels in the mid-1980s, have affected the head difference (or disparity in elevation) between Lake Huron and Lake Erie.
The report indicates that the total decline in the head difference between Michigan-Huron and Erie between 1963 (following the last major navigational channel dredging in the St. Clair River) and 2006 is about 23 centimetres or almost a quarter metre.
Primary reasons for the difference include less precipitation in the northern portion of the upper Great Lakes Basin, compared to Lake Erie, along with chronic long-term decline of ice cover during winter months. Michigan and Huron have experienced almost drought-like conditions since the last high-water period in the 1990s.
Unlike Lake Superior, whose outflow can be partly adjusted, Michigan and Huron depend on rain/snowfall and runoff for about 75 per cent of their water inflow, with the balance coming from Lake Superior. By contrast, about 80 per cent of Lake Erie’s water supply comes from Lake Huron. Only 20 per cent of its water supply comes from precipitation and runoff. Consequently, Lake Erie has not been affected as severely by less precipitation.
The report on the St. Clair River is part of a broad study and evaluation process that now shifts to the regulation of Lake Superior outflows, with a final report expected to provide recommendations in 2012.
Public submissions and comments to the St. Clair River report can be forwarded to the IJC until April 9 of this year.
Funded equally by the U.S. and Canadian governments, the $17-million IUGLS (total spending for both the St. Clair and Lake Superior phases) was sanctioned by the IJC under the authority of the Boundary Water Treaty. The IJC is a bi-national organization mandated to resolve boundary water issues and disputes that the two countries may have.