This depiction shows water moving through the water cycle in Illinois and is based on 30-year (1971-2000) averages calculated by Illinois State Water Survey scientists. Values are in billions of gallons of water per day (BGD) and include: atmospheric moisture passing overhead (2000 BGD), precipitation (104 BGD), evapotranspiration (73 BGD), surface water flow (31 BGD), and groundwater recharge (11.6 BGD, of which 11.5 BGD is returned as groundwater discharge to surface streams). Additional surface water flows into Illinois from rivers in Indiana and Wisconsin, and water is imported into Illinois through the diversion from Lake Michigan at Chicago. Much of the water in the Mississippi, Ohio, and Wabash Rivers originates upstream of Illinois.
Except where indicated, all photos/graphics have been taken/produced by Water Survey staff.