Water levels in the Great Lakes are nearing record lows this year.
Jim Biddle, the owner of Biddle Marine Services in St. Williams, Ont. told The Star that boaters on Lake Erie were "playing Russian roulette", adding that "boaters are running into rocks a mile off shore."
According to Environment Canada, Lakes Michigan, Huron and Superior were already running below the 100-year average last year, and now all the Great Lakes are running below that average — Lake Erie at 22 cm below average, Lake Ontario at 23 cm below average, Lakes Michigan-Huron at 63 cm below average and Lake Superior at 34 cm below average.
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The main reason for the low water levels in the lakes this year is due to the warm winter and dry summer. Last winter was considered to be the warmest in decades according to Environment Canada, producing little to no snow pack around the lakes and the lowest 'total accumulated ice coverage' on the lakes since records began back in 1972-73, and this past summer was extremely dry from coast to coast.
The entire Great Lakes Basin is above sea level, with Lake Superior the highest at 180 metres above sea level, then Lakes Michigan and Huron at 176 m, Lake Erie at 174 m, and Lake Ontario lowest at 74 m above sea level. The St. Lawrence River runs downhill from there to the east coast. Any water in the Great Lakes will generally obey gravity and cascade down through the waterways until it reaches the Atlantic Ocean.
Water that would have normally been stored up in the snow pack and lake ice during the winter, for slow release during the spring melt, was instead free to run its course through the lakes. With very little rainfall making it out of the drought-stricken U.S. this spring and summer to replenish this lost water, levels have dropped to their current state.
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There is a human component to this, of course. The lakes have always had a natural way to limit the amount of water that can flow out of it at any time, in the form of the rivers that interconnect the lakes. Dredging of these rivers, to allow for larger commercial vessels to pass through them, have also opened up the way for more water to flow through them, thus depleting the lakes at a faster rate.
The low water levels may have been partially responsible for the mass deaths of thousands of fish in Lake Erie two weeks ago. Examination of the fish found that they died due to natural causes when oxygen levels dropped in the lake. This may have been caused by an algae bloom, or possibly a sudden 'lake inversion', where a cooling of the surface of the lake — by stormy or windy conditions — causes the oxygen-rich upper layer of lake water to exchange with the oxygen-deficit lower layer, suffocating any fish near the surface. In either case, the lower the water levels in the lake, the easier it would be for either of those scenarios to cause the die-off.