The Great Lakes of the United States are the largest collection of freshwater on Earth, providing the region with plenty of freshwater as a resource for drinking, farming and even recreation. Despite the plentiful amount of freshwater in this system, there are still many reasons hydrologists are protective of the Great Lakes. Collectively, the Great Lakes have plenty of water to support the Midwest region, but individually, some of the lakes are being stressed and the water supply is being threatened. Also, invasive species have found their way into the lakes and have further stressed the ecosystem. Contamination, even from long ago human activity, still persists today.
The Five Great Lakes
The Great Lakes are so named because they are large in both area and volume, holding 21 percent of the world's surface freshwater. The total surface area of these five lakes is the largest on Earth at 94,250 square miles. The total volume is 5,439 cubic miles, coming in second behind Russia's Baikal Lake. Lake Superior is the dominant lake in surface area, water volume and average depth, with a maximum depth of over 1,000 feet in some places.
The five Great Lakes and their physical dimensions are:
- Lake Superior - 31,700 square miles; 2,900 cubic miles of water; 1,335 feet maximum depth.
- Lake Ontario - 7,340 square miles; 393 cubic miles of water; 804 feet maximum depth.
- Lake Michigan - 22,300 square miles; 1,180 cubic miles of water; 925 feet maximum depth.
- Lake Huron - 23,000 square miles; 1,180 cubic miles of water; 748 feet maximum depth.
- Lake Erie - 9,910 square miles; 116 cubic miles of water; 210 feet maximum depth.
Approximately 30 million Americans and Canadians live within the Great Lakes Basin. Not only do they depend of the freshwater from these lakes, but also waste water from human activities in the region is returned to the basin.
Studying the Great Lakes
There are many programs that sponsor scientific research of the Great Lakes. These programs are funded by the federal government and by local communities who depend on natural resources from the Great Lakes ecosystem. Two of the major federal programs for studying the Great Lakes are the U.S. Geological Survey's Great Lakes Science Center, headquartered in Ann Arbor, MI, and the Great Lakes Restoration Program, which is sponsored by the EPA. Both of these programs require coordination with local communities, tribal communities, and other local, state or federal agencies that are able to identify potential hazards to the lakes and ways to mitigate those hazards.
One major hazard to the Great Lakes is contamination from human activities. In 2002, the Great Lakes Legacy Act was signed into law which would make federal funds available for cleaning up "Areas of Concern," or AOCs. Although discharge of toxic substances has decreased in the last 20 years, thanks to government regulation of pollution, many of the toxic substances that were released prior to regulation are still trapped within the sediment of the Great Lakes and its tributaries. There are 43 AOCs throughout the Great Lakes, and 31 of them are located on the U.S. side of the Great Lakes. Contaminants in these AOCs have been known to cause harm to humans and wildlife, and there are even warnings against consuming fish from these AOCs. Invasive species are also a major concern for the Great Lakes, and many scientific programs are dedicated to finding solutions to the invasive species problems.
Sources:
The Great Lakes Legacy Act, epa.gov
USGS Great Lakes Science Center, usgs.gov
Alexandra Matiella Novak - With a PhD in Geology and expertise in science education, Alexandra is passionate about increasing the public's Earth science literacy.
