Like any body of water, over the years Georgian Bay water levels have gone up and down. Since records have been kept, it was at it’s highest in 1986 when it reached 177.50 meters above sea level. The lowest watermark was in 1964 when it was almost 2 meters lower. 2012 may surpass the lowest record - last summer the Island Queen was unable to sail through the Rose Point Road channel.
Why worry about the water levels? Lower water levels affect the Parry Sound area as it impacts on the coastal wetlands and fish spawning; the impact on local property owners over changing shorelines and connecting channels between land masses; and, the impact on the local economy in tourism and marinas (whose business is primarily recreational boaters). Just check out all the different activities that depend on the water.
In the past, theories put forward for explaining the drop in water levels were the dredging and other man-made changes done in the 1960’s to the St. Clair River. However, the latest reports indicate it is the changing climate and low water supplies that are having the biggest impact.
Precipitation ad/or the lack of it plus evaporation can have a big impact on water levels. During the winters of 2009 - 2011, we have experienced much less snowfall in Parry Sound; it has melted sooner than usual, and we have had a very dry summer, leaving a lower than normal water table level.
However, there is another factor that is not in the control of man, and that is Glacial Isostatic Adjustment. During the last Ice Age, the ice was more than a meter thick and depressed the Canadian Shield. Once the glaciers melted, the earth began to rise. Using GPS, scientists can measure the uplift. However, the primary issue is that some areas are rising faster than others, creating a tilt in the Great Lakes Basin.
So, while Parry sound is experiencing lower water levels, those at the south end of Lake Michigan are dealing with a sinking shoreline and the threat of serious flooding and shore erosion. As over 10 million people live in that area, do the people of Georgian Bay have the right to complain? I think not.
*(Adapted from Wed. Sept 7, 2011 Parry Sound North Star article written by David Foote.)