Water Quantity The Great Lakes are "the dominant hydrologic feature in midcontinental North America." The Great Lakes System extends over 2,000 miles, has a surface area of 95,000 square miles, and is the largest freshwater lake system in the world. The large surface area and storage volume of the Great Lakes System act as a natural regulator of lake water levels. The range from the highest quantity stored to the lowest quantity stored is only about 1.3% of the average volume of water contained in the lakes. The modulating effect means that a change in water supplies to the upper part of the system remains within the system for as long as 15 years before the full effect is felt downstream. Lake Michigan is the only one of five Great Lakes which is not a boundary water between the U.S. and Canada. The lake lies solely within the United States and is shared by Michigan, Wisconsin, Illinois, and Indiana. Lake Michigan is 307 miles long and 118 miles wide, with an average natural depth of 279 feet. The Straits of Mackinac connect Lake Michigan and Lake Huron, the two lakes respond to precipitation and changes in levels and flows as if they were one. Although the net flow is eastward, the direction of current in the straits changes depending upon barometric pressure and wind conditions1. Toward the end of the nineteenth century, the nation's population was rapidly moving westward. Industrialists followed this wave and moved their plants closer to Midwest markets. Chicago had become the "great city of Middle America;" more railroads converged there than any other point in the world. In addition, Lake Michigan provided cheap water transportation and abundance of water for industrial purposes2. As Chicago grew, areas along the Chicago River became too valuable for industrial interests. Land in this rapidly urbanizing area was unavailable to companies with plans for expansion. Industries looked to the areas south of Chicago for relocation. Major industries found the land, transportation, and water, in Indiana. The Standard Oil Company opened the largest refinery in the world in 1890 in Whiting. In 1901, Inland Steel Company obtained land along the lakeshore in what is now East Chicago. The United States Steel Corporation received its first shipment of iron ore in 1908.3 Northwest Indiana became a major industrial center of the country as more and more industries found their home near Lake Michigan. Farther south in the Lake Michigan basin, ground water was the primary source of water for drinking and agricultural purposes. The availability of ground water is associated with the nature and type of aquifer materials present in a given area. In the southern portion of the basin, closer to the Kankakee River valley, outwash sand and gravel deposits are present yielding high quantities of ground water4. Total withdrawals in the Lake Michigan area, including the St. Joseph River basin, totaled 1,096 billion gallons during 1994. The total withdrawals for the same area during 1996 decreased to 1,058 billion gallons. Registered water withdrawals for industrial purposes claimed 54.7% of the water withdrawn in 1994, and 58.7% in 1996. Energy production, the second highest water-use category, accounted for 37.8% of the total withdrawals for the area in 1994. In 1996, energy production accounted for 35.4% of the total withdrawals. Most water withdrawals for industrial purposes and for energy production are returned to Lake Michigan. Public water supply water-use was 5.0% of the total water use in the area during 1994 and 5.3% in 19965. Based on 1990 census data, the estimate is 14% of the Lake Michigan basin residents obtain their water from nonregistered wells, accounting for about 0.2% of all water withdrawals. Registered water withdrawals for agriculture and other miscellaneous purposes constitute approximately 0.2% of the total water withdrawals in the Lake Michigan area6. 
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