Great Lakes / Water Quality

The cancer of the Great Lakes

Every year, an untold number of foreign organisms find their way into the Great Lakes in shipping ballast water. (Credit: Garitzko / Wikipedia)

NEW YORK, NY — “On a map, Lake St. Clair looks like a 24-mile-wide aneurysm in the river system east of Detroit that connects Lake Huron to Lake Erie, and that is essentially what it is. Water pools in it and then churns through as the outflows from Lakes Superior, Michigan, and Huron tumble down into Erie, then continue flowing east over Niagara Falls into Lake Ontario, and finally down the St. Lawrence Seaway and out to the Atlantic Ocean.

…Water rushes so quickly through Lake St. Clair because it is as shallow as a swimming pool in most places, except for an approximately 30-foot-deep navigation channel down its middle. The U.S. Army Corps of Engineers carved that pathway in the late 1950s as part of the Seaway project to allow oceangoing freighters to sail between Lake Erie and the lakes upstream from it. When water levels were low or sediment high, sometimes that channel still wasn’t deep enough, forcing ships to lighten their loads to squeeze through. This often meant dumping water from the ship-steadying ballast tanks—water taken onboard outside the Great Lakes. Water that could be swarming with exotic life picked up at ports across the planet.

…Nobody gave it much thought at the time, but in the years following the Seaway’s opening in 1959, species not native to the Great Lakes, ranging from algae to mollusks to fish, started turning up at a rate never before seen.”

— Dan Egan, Nautilus

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