where do the great lakes get their water
Great Lakes In 2009, the lakes contained 84% of the surface freshwater of North America;[40] if the water were evenly distributed over the entire continent's land area, it would reach a depth of 1.5 meters (5 feet).[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 level of the lakes constant.[15] While the lake levels have been preserved, intensive human population growth only 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]
Lake Michigan Lake Michigan has a surface area of 22,404 sq.mi (58,026 km2); (13,237 square miles, 34,284 km2 lying in Michigan state,[2] 7,358 square miles, 19,056 km2 in Wisconsin, 234 square miles, 606 km2 in Indiana, & 1,576 square miles, 4,079 km2 in Illinois) making it the largest lake entirely within one country by surface area (Lake Baikal, in Russia, is larger by water volume), and the fifth-largest lake in the world. It is the larger half of Lake Michigan–Huron, which is the largest body of fresh water in the world by surface area. It is 307 miles (494 km) long by 118 miles (190 km) wide with a shoreline 1,640 miles (2,640 km) long. The lake's average depth is 46 fathoms 3 feet (279 ft; 85 m), while its greatest depth is 153 fathoms 5 feet (923 ft; 281 m).[2][20] It contains a volume of 1,180 cubic miles (4,918 km³) of water. Green Bay in the northwest is its largest bay. Grand Traverse Bay in its northeast is another large bay. Its deepest region, which lies in its northern-half, is called Chippewa Basin (named after prehistoric Lake Chippewa) and is separated from South Chippewa Basin, by a relatively shallower area called the Mid Lake Plateau.[21][22]