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Georgian Bay level to remain low


kickingfrog

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http://www.thebarrieexaminer.com/2014/03/02/georgian-bay-water-levels-expected-to-remain-low-despite-snowy-winter-official

 

Georgian Bay water levels expected to remain low despite snowy winter: official

 

 

 

A snowy, cold winter has brought winter water levels in Georgian Bay back up to where they were in 2012, but an adviser to the transnational body that oversees the Great Lakes says they’ll likely remain below average this season.

“The average rise from winter to spring is about 30 centimetres. With everything else being equal, we expect water levels to be still roughly 30 centimetres below average,” said David Fay, engineering adviser to the International Joint Commission.

The determining factor, he said, will be how much rain we get in the spring.

“Right now, with the increase in snow accumulation, the ice cover on the lakes, things are suggesting that we’re going to have a greater-than-average rise,” Fay said.

For more than a decade, water levels in Georgian Bay and in lakes Michigan and Huron have steadily dropped and reached an all-time record low of 175.57 metres above sea level in January 2013.

While the long-term average in the summer is about 176.57 metres above sea level, the long-term mid-February average is about 176.28 metres above sea level. Right now, the water level in Georgian Bay is sitting about 175.95 metres above sea level.

“We’re roughly 40 centimetres higher than the lowest point that we reached last year,” Fay said. “It’s still well below average, but it’s a nice recovery.”

The Great Lakes are 82% ice covered. Lake Huron, including Georgian Bay, is about 92% ice covered.

It’s twice as much as normal, Fay said, and more than it has been since 1994.

“It’s unusual, especially compared to the past few years, which have had much below-normal ice coverage,” he said.

So far this year, Fay said the total amount of precipitation for January and February is actually below average, but the winter has been exceptionally cold, which means more snow has accumulated because it hasn’t been thawing and melting.

“We reach the low point of the seasonal cycles in the winter, in January, typically. It’s because there’s evaporation on the falls, there’s basically very little runoff to the lake in the winter because of accumulation of snow. Then, of course, in the spring, if the snow melts and we get summer rains, there’s quite a bit of runoff from the rivers into the lakes and the lakes’ levels rise the most that they do,” he said.

“People’s memories tend to be rather short. A decade of relatively low, below-average water levels actually goes back to 1999, when water levels crossed from above average to below average on Lake Huron. Basically, we’re at the 15-year point now of below-average water levels and people are forgetting what average water levels are,” Fay said.

An April 2013 report by the International Joint Commission attributed a significant portion of the decline in Georgian Bay water levels to dredging that took place between 1920 and 1960 to widen the St. Clair River, which connects Lake Huron and Lake Erie, so freight ships could fit through. The commission formally recommended the Canadian and American governments investigate installing water-control structures — like dams or sills or dikes — in the river stop the water from rushing out of Lake Huron.

Neither government has issued a formal response to the recommendation.

“That’s just one of the factors that’s affecting lake levels, especially on Michigan and Huron. The biggest one is the variability in the climate and the possibility of climate change,” Fay said.

Generally, climate models project Great Lakes water levels will climb because there will be more evaporation from their surfaces, he said.

“Why it’s so difficult to say with much confidence as to what’s going to happen in the long term with Great Lakes water levels is, generally, with the warmer climate, there will also be more water vapour in the air and more precipitation,” he continued. “There’s a lot of uncertainty in all that science, so it may be that there’s more evaporation from the lakes that would not be offset completely by the precipitation or it might be in the future that there’s greater precipitation that more than offsets the increase in evaporation so the net effect might be more water.”

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That's quite a misleading report. Of course they will remain below average! As the article says, they have been falling below average for the last 15 years. You'd hardly expect levels would recover in 1 year. But if you read further down you can see that they are predicting quite a nice rebound this year.

 

It also says the study commissioned by the IJC recommended that gov'ts 'investigate installing water control structure, They did not recommend that because they be specifically told in their mandate not to make recommendations re these structures.

 

It also says that that dredging of the St. Clair river produced a 'significant' drop. While that may be true in the most literal sense, the study showed that the effect was minor compared to others such as evaporation.

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