LAKE MICHIGAN IS 1 of the 5 original Great Lakes, which are located near or along the border between the United States and Canada; a sixth lake, Lake Champlain, was added to the Great Lakes category in 1998. The Great Lakes are the largest group of freshwater lakes in the world, and Lake Michigan is the only 1 located entirely within the United States; its waters are contained within the states of Indiana, Illinois, Wisconsin, and Michigan.
This body of water is 22,300 square mile (57,800 square kilometer). It has the third-largest surface area of the Great Lakes, and is the sixth largest lake in the world. It connects to Lake Huron through the Straits of Mackinac and the 2 lakes are, hydrologically speaking, inseparable. The lake’s drainage basin, the area of land where streams and rivers that drain into the lake exist, nearly doubles the lake’s scope at 45,600 square mile (118,000 square kilometer). Rivers such as the Fox-Wolf, Grand, Kalamazoo, Menonimee, Muskegon, and Saint Joseph are among the most notable. Via the Chicago River, Lake Michigan also connects to the Mississippi River basin and then the Gulf of Mexico.
Lake Michigan is 307 mile (494 kilometer) long and 118 mile (190 kilometer) wide, with an average depth of 279 foot (85 m and a maximum depth of 925 foot (282 meter). It contains 1,180 cubic mile (4,920 cubic kilometer) of water, and averages 577 foot (176 meter) above sea level. The shoreline is 1,638 mile (2,633 kilometer) long when its island shorelines are considered.
Lake Michigan’s name also went through a series of changes. Explorer Samuel de Champlain named it Grand Lac in the early 17th century. Later names included Lake of the Stinking Water, and Lake of the Puants, after people living nearby, as well as Lac des Illinois, Lac St. Joseph, and Lac Dauphin. Explorers Louis Jolliet and Père Jacques Marquette gave this body of water the name by which we know it today, which is derived from a Native American designation, Michi-guma, meaning “big water.”
The Sleeping Bear Sand Dunes, a spectacular feat of nature located in a national park, hovers 465 foot (142 meter) above Lake Michigan and extends 35 mile (60 kilometer) along its eastern shoreline. At this site, visitors can observe windswept dunes and other glacial formations.
A wide variety of fish live in Lake Michigan, including salmon, perch, bass, and walleye. Trout and whitefish are especially prized. By the late 1950s, many fish had been killed by an eellike creature called sea lamprey; although that problem has been alleviated, another greater problem still exists: pollution.
Lake Michigan’s waters have been polluted from sewage and industrial waste, in part because its large surface area is a ready target for toxins falling from the atmosphere. At 1 time, Chicago’s waste was dumped into the Chicago River, which flowed directly into Lake Michigan, and many other towns also dumped their raw sewage into the lake. Lake Michigan has a retention time of 99 years, which means that a molecule of water that enters the lake will, on average, take 99 years to leave its confines. Clearly, then, the contaminants entering the lake were accumulating; aggravating the problem was the fact that Lake Michigan was a closed ecological system. Although many rivers flowed into the lake, none flowed out. To alleviate the pollution problem, engineers reconfigured the course of the Chicago River in 1900 so that it actually flowed away from the lake, thereby reducing the surge of sewage and chemical waste into Lake Michigan. Stricter environmental laws have also reduced the amount of industrial pollutants entering the water. In 1990, Congress passed the Great Lakes Critical Programs Act, which mandated more programs to reduce toxic pollutants so that Lake Michigan and other Great Lakes can be restored to a more healthful and stable condition.
BIBLIOGRAPHY. Ann Armbruster, Lake Michigan (Grolier Publishing, 1996); Harry Beckett, Lake Michigan: Great Lakes of North America (Rourke Corporation, 1999); Lake Michigan Federation, www.lakemichigan.org (April 2004); Great Lakes Information Network, www.great-lakes.net (April 2004); Lake Michigan Forum, www.lkmichiganfo rum.org (April 2004).
KELLY BOYER SAGERT