By Daniel Macfarlane
Lake Huron and Lake Michigan recently reached record lows. The other Great Lakes are also below average levels. Headlines such as “Two Great Lakes hit lowest water levels in history” or “Low water levels in Great Lakes cause concern” have been splashed across browsers and newspapers. Docks barely reach water, boats can’t get out of marinas, and beaches have seemingly doubled in size. What is causing these lows? There are a range of human efforts that influence lake levels: diversions out of the Great Lakes basin (e.g. Chicago Sanitary and Ship Canal or Ogoki-Long Lac); dredging in connecting channels (e.g. St. Clair and Detroit rivers); regulating works (e.g. dams in the St. Mary’s and St. Lawrence rivers), or consumptive uses ranging from agriculture to exporting bottled water, beer, pop, etc.
These dams and diversions certainly have negative ecological effects. But, compared to natural causes, they have only minimal impacts on water levels. Natural factors and cycles are the main causes of water level variability, although the recent extremes are almost certainly attributable to climate change and altered precipitation levels. Continue reading




