The Great Lakes

With Great Lakes Comes Great Responsibility… for Canada and the U.S.

Understanding Lake Erie and its place in the Great Lakes system can only enhance understanding of the pollution and cyanobacterial problem.  Water flows into Lake Erie from the three larger lakes as well as some smaller lakes and rivers.  The Detroit River is the direct source, bringing water from the other lakes through Lake St. Clair into Lake Erie.[1]  The Maumee is another source of water, and although not as much water flows from it, the water that does contains a larger proportion of pollutants.

Physical Features

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Image courtesy of the EPA

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The above statistics give a great overview of the Great Lakes, and highlighted you’ll find Lake Erie’s stats.  The table shows how small Erie is compared to the others, especially Lake Superior.  While Ontario is also a small Lake, Erie is in many ways smaller, most significantly in terms of depth and retention time.

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The above image shows the 5 Great Lakes, their approximate watershed areas, the direction water flows through the system, and (added in green) the number of years the lake retains water.  From this we can see that Lake Erie gets water from three of the other lakes, as well as from the watersheds in the land directly around it.  We can also see how quickly the water flows through the lake (2.6 years), in comparison to the others at least.  The United States/Canadian border can also been seen cutting four of the lakes in half.

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This visual gives us a look at the sizes of the lakes as if from the side.  We see very clearly the depth and elevation of each lake.  Lake Erie is hundreds of feet shallower than the other lakes, at only about 200 feet deep maximum.  The minor lakes and the rivers are also seen here, giving us a more complete image of the system as a whole.

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This chart shows us the dimensions of all the lakes, and the size differences between Erie and Ontario are most apparent.  Erie is also at a slightly lower elevation than the three preceding lakes, and feeds Niagara Falls, which empty into Lake Ontario.  Though the maximum depth of Lake Erie is 210 feet, we can see here that the average depth is only 62 feet.  This is why dredging is both necessary and a risk for the lake: ships have to get through, but the dredging process can dredge up once-settled nutrients and promote the spread of invasive mussels.

Lake Erie Stats:

Bordered by: Ohio, Pennsylvania, Michigan, New York and Ontario.
Inflow from Detroit (and Maumee) River(s)
Outflow to Niagara River
Dimensions: 241 mi long by 57 mi wide by 210 ft deep max (62 ft av.)
Surface Area: 9.910 mi sq.
Water Volume: 116 mi cu
Islands: 31 total, 13 Canadian, 18 American
Water Cycle: 2.6 years[2]

While Lake Erie’s cyanobacterial problem affects Toledo and the surrounding area most prominently, the cleanliness of the lake is not just an Ohio problem.  In fact, it’s not even just an American problem.  Four of the Great Lakes (the exception is Michigan) are divided between the United States and Canada, and all the water that feeds the lakes (except Michigan) originates from Canada.  So while much of Lake Erie’s issues affect Toledo and other parts of Ohio, it is important to remember that Canada is on the other side of that lake, and actually has more shoreline than any US state.  This internationality affects those other three lakes (Superior, Huron, and Ontario) just as much, so the health of the Great Lakes is a concern of both countries.  This is reflected in policies regarding the lakes.[3]

While Lake Ontario is slightly smaller than Lake Erie in some ways, Lake Erie is significantly shallower and contains much less water.  It has a larger drainage area and a longer shoreline (islands included), which altogether means that Lake Erie is more susceptible to pollution than the other lakes.[4]  On the other hand, water moves through Lake Erie much faster than the other lakes, meaning that once the active pollution of the lake stops, it will be able to refresh itself rather quickly.

What this all means is that preventing pollution from entering Lake Erie in particular is really important, but cleaning existing pollution isn’t as big an issue because in less than three years the lake can replace all of its water.  However, this also means that keeping the whole Great Lake system clean is important, because the lakes flow into one another, and the other lakes don’t refresh as often – Lake Superior, for example, takes almost 200 years to replenish its water supply; and Michigan takes about 100 years.[5][6]

Lake St. Clair is a smaller lake just above Lake Erie, it is in the same watershed and shares a lot of the same issues.

For more information specifically on Lake Erie as well as Lake St. Clair an the surrounding area, see Lake Erie.

Great Lakes Drainage Basins

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