|How is Water Used in Illinois?
Water is used for many diverse purposes. In-stream uses include sustaining fish and
wildlife habitats, maintaining water quality, generating power, navigating the larger rivers,
recreation and aesthetics, and overall biological integrity of rivers and streams. Water quantity,
quality, and riverine health are all closely connected. Groundwater is withdrawn for public,
industrial, and commercial uses and is also a major source of water for irrigation. Withdrawals of
groundwater in Illinois average about 1 billion gallons per day (bgd) and serve about a third of the
In the 1990s, Illinois used 20 bgd, and 95% (19 bgd) came from surface water sources.
Thermoelectric power generation, easily the state’s greatest water user, used 17 bgd, and much of
this was recycled. Four other major uses of water in Illinois (see graph) amount to 3 bgd, with
public water supplies being the second largest user of water. Usage of public water supplies has
grown substantially: from 36% of nonpower plant usage in Illinois during 1950, to 63% in 1998.
Northeastern Illinois, the state’s major consumer of water, depends heavily on water from
Lake Michigan. Groundwater pumpage is also a large source of water for many Chicago suburbs.
Diversion of lake water averages 3,200 cubic feet per second (about 2 bgd); about 1.1 bgd is for public water supply which represents 41% of
Illinois’ total water withdrawals for all purposes, excluding power generation. Water usage values for
Illinois must be used with caution because reporting is voluntary, and many users do not report
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This graph shows the water withdrawals by category, 1950 to 1998 (excluding power generation). Sources include mining, self-supplied
industry, rural (domestic, livestock, irrigation), public water supply.
This table show fresh water withdrawals during 1995, in millions of gallons per day. Topping the list is thermoelectric, followed by domestic
and public supply, self-supplied industries, and livestock and irrigation.
This graph displays Illinois contemporary water withdrawals by source (excluding power generation). Sources of withdrawal include ground water,
surface water, and Lake Michigan.