Low Water Levels Not Linked to Erosion of St. Clair River

TORONTO _ The first results from underwater video studies of 30 miles of the St. Clair River show no evidence that the riverbed is eroding and contributing to low water levels on Lakes Huron and Michigan, researchers said Thursday.

Bommanna Krishnappan, research scientist with Canad a’s National Water Research Institute, said pictures show that the riverbed has a layer of coarse gravel pieces, pebbles and stones that range in size from one-sixth of an inch to nearly 10 inches in diameter .

That makes the riverbed stable, he said, and means it can’t be eroding .

The findings contrast with those of a private Canadian study in 2005, funded by a group of homeowners on Georgian Bay. That study claimed the riverbed was continuing to erode as a result of past dredging, making the river channel larger and draining water rapidly from Lakes Michigan and Huron.

The researchers argued that the river had become, in effect, a larger bathtub drain hole.

The homeowners group said Lake Erie remained near its normal long-term levels, while the upper lakes were far below theirs, and the answer to that puzzle was that the speeding river was letting more water into Lake Erie.

Climate alone, not dredging, can explain the difference in levels among the three lakes, said Frank Quinn, a climatologist who also spoke Thursday at a conference on the climatology of the Great L akes.

Quinn said rather than more water going into Lake Erie from the upper lakes, data going back to the 1960s show less flow than in past decades. Erie’s level is relatively higher than those of its northern neighbors because the drainage basin that feeds it is wetter.

More rain and runoff are reaching the lake than in the past, and Lake Erie has had less evaporation than Lakes Michigan and Huron. Those two lakes had a sudden, rapid uptick in evaporation starting about 2005, Quinn said.

The video results don’t necessarily mean the river isn’t flowing faster than it did in the past, but they do say that the river is not eroding and becoming deeper, said Eugene Stakhiv, co leader of the International Joint Commission’s study, which involves U.S. and Canadian researchers.

“What we’re saying is the assumption that the river bottom is sand and clay is incorrect,” Stakhiv said.

Roger Gauthier, a hydrologist for the Great Lakes Commission, said Thursday that he was unconvinced erosion is not a factor.

“What they found is a piece of a complex puzzle,” he said of the video. “It’s not the answer. For them to say there is no erosion, based on the video, is premature.”

The study, which will end by June 2009, still has more work, he said.

Gov. Jennifer Granholm, Sen. Debbie Stabenow and Rep. Candice Miller of Michigan have urged the Army Corps of Engineers to consider a quick fix for the river bottom, such as concrete speed bumps or boulders, to slow the river’s flow. That should be done before the study is finished, they said.

Not everyone nearby supports that idea. Mayor Mike Bradley of Sarnia, Ontario, at the head of the St. Clair River, wrote a letter to officials Monday urging them to oppose any attempts to make a quick fix to the river.

More man-made changes “have the potential to create many more problems than they resolve,” he said. “The idea of adding a flow inhibitor at this time, not based on science or engineering but on politics, is appalling.”

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