The Great Lakes contain 21% of the world's surface fresh water: 5,472 cubic miles (22,810 km3), or 6.0×1015 U.S. gallons, that is 6 quadrillion U.S gallons, (2.3×1016 liters). The lakes contain about 84% of the surface freshwater of North America;[53] if the water were evenly distributed over the entire continent's land area, it would reach a depth of 5 feet (1.5 meters).[54] This is enough water to cover the 48 contiguous U.S. states to a uniform depth of 9.5 feet (2.9 m). Although the lakes contain a large percentage of the world's fresh water, the Great Lakes supply only a small portion of U.S. drinking water on a national basis.[55]
The total surface area of the lakes is approximately 94,250 square miles (244,100 km2)—nearly the same size as the United Kingdom, and larger than the U.S. states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, and New Hampshire combined.[56] The Great Lakes coast measures approximately 10,500 miles (16,900 km);,[15] but the length of a coastline is impossible to measure exactly and is not a well-defined measure. Canada borders approximately 5,200 miles (8,400 km) of coastline, while the remaining 5,300 miles (8,500 km) are bordered by the United States. Michigan has the longest shoreline of the United States, bordering roughly 3,288 miles (5,292 km) of lakes, followed by Wisconsin (820 miles (1,320 km)), New York (473 miles (761 km)), and Ohio (312 miles (502 km)).[57] Traversing the shoreline of all the lakes would cover a distance roughly equivalent to travelling half-way around the world at the equator.[15]
The source of water levels in the lakes is tied to what was left by melting glaciers when the lakes took their present form. Annually, only about 1% is "new" water originating from rivers, precipitation, and groundwater springs that drain into the lakes. Historically, evaporation has been balanced by drainage, making the levels of the lakes relatively constant.[15]
Intensive human population growth began in the region in the 20th century and continues today.[15] At least two human water use activities have been identified as having the potential to affect the lakes' levels: diversion (the transfer of water to other watersheds) and consumption (substantially done today by the use of lake water to power and cool electric generation plants, resulting in evaporation).[41] Fluctuation of the water levels in the lakes has been observed since records began in 1918.[42] The water level of Lake Michigan–Huron had remained fairly constant over the 20th century[43] Recent lake levels include record low levels in 2013 in Lakes Superior, Erie, and Michigan-Huron,[44] followed by record high levels in 2020[45] in the same lakes. The water level in Lake Ontario has remained relatively constant in the same time period, hovering around the historical average level. [42]
The lake levels are affected primarily by changes in regional meteorology and climatology. The outflows from lakes Superior and Ontario are regulated, while the outflows of Michigan-Huron and Erie are not regulated at all. Ontario is the most tightly regulated, with its outflow controlled by the Moses-Saunders Power Dam, which explains its consistent historical lake levels.[46]o
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The big questions are: (1) What would Canada say; and (2) What would the people of the MidWest say; and (3) what would the environmentalists say. These are the people that have to be placated to divert Great Lakes Water to the Western region.
The idea is not so uncommon as you might think. I live on a North Carolina lake system that provides water for the Virginia shoreline and deals are cut to compensate North Carolina appropriately. Drinking water delivered to 445,000 Virginia Beach citizens comes from the Lake Gaston Water Supply Pipeline. It's a 76-mile-long pipeline leading from Lake Gaston, in Brunswick County, to Lake Prince, a reservoir located in Suffolk, but owned and operated by the City of Norfolk.
