The Canada-U.S. agency investigating claims that the Great Lakes have sprung a giant leak on the St. Clair River near Sarnia says preliminary research doesn't support the idea that recent erosion on the river's bed is causing nearby Lake Huron to lose increasing amounts of water.
The International Joint Commission said yesterday in an interim report that extensive videotaping of the deepest parts of the river's bed by Canadian scientists showed it to be stable, with large rocks and gravel protecting it from washing away.
There have been concerns about water losses from Lake Huron ever since the Georgian Bay Association, a Canadian environmental group, made the claim in 2005 that the Great Lakes had developed a larger drain hole on the St. Clair River. Last summer, the group updated its claim and said the losses could be massive - nearly 10 billion litres a day, or enough for 4,000 Olympic-sized pools.
But the commission's report concluded that "the armour layer [of rocks] in the upper part of the St. Clair River is considered to be stable. Therefore, the bed cannot be eroding."
Those working on the report told a news conference yesterday in Toronto that they are not yet in a position to definitively reject or prove the assertion that the river is draining abnormal amounts of water because they haven't checked its flow across its entire depth. But the finding of stability at its deepest parts, where the current tends to be strongest, is a good sign because there had been fears that the river bottom was composed mostly of clay and fine sand, which is more susceptible to washing away.
"We feel that this bed is fairly stable but we still have to look at the cross-section," said Ted Yuzyk, a co-director of the agency's effort charged with investigating water flows in the river.
The commission normally doesn't issue preliminary reports such as the one released yesterday, but the question of whether the Great Lakes are becoming a little less great due to shrinkage has become a burning political issue in areas of Canada and the U.S. adjacent to the giant water system.
The agency also released pictures of the rocks at the bottom of the river to prove its point about the lack of erosion.
The levels of the three upper lakes - Superior, Michigan and Huron - are at some of their lowest readings in decades. Superior is low in part because of a drought and lack of wintertime ice. But the suggestions of extra drainage on the St. Clair have led to fears that Michigan and Huron, which are connected and share the same water level, are lower than they should be. Many near-shore areas around the two lakes have recently dried up, alarming residents.
The Georgian Bay Association made its claim about increased drainage based on an independent hydrological evaluation. It said it is too early to refute its allegations. "I think this is premature," said Mary Muter, a spokesperson for the group.
The association blames dredging conducted in 1962 for causing increased water flow out of Lake Huron. That dredging, done by the U. S. Army Corps of Engineers, was supposed to be accompanied by protection against erosion, but this work was never done because of high water on the lakes in the 1970s and 1980s.
It is possible that the dredging has led to outflows that are now greater than they would otherwise be, even though the riverbed now looks relatively stable. In its future research, the bi-national agency will examine this possibility. It is expected to complete its review by February, 2009.
The agency, run by the Canadian and U.S. governments, is unable to answer questions about changes to the flow out of Lake Huron in part because there hasn't been regular monitoring with hydraulic flow meters of the amount of water entering the St. Clair River. Mr. Yuzyk said new meters are to be in place soon.