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Hennepin-Hopper Lakes, May 2008
Putnam County
A variety of bottomland lakes occur along the Illinois River. These shallow lakes, from less than an acre to a few thousands acres, occur along the river's wide floodplain, by definition a flat expanse of land. Flood waters may be exchanged between the river and the bottomland lakes depending upon the various water levels of each lake and the river. Because the river's floodplain provides deep, flat, rich soil, it is ideal for farming...except when it floods. So like many rivers in the Midwest, much of the Illinois River's floodplain has been protected from the river by a system of levees. Hennepin-Hopper Lakes have been restored from farmland, but are still separated from the Illinois River by a levee system. Because of this, the lakes are fed only from groundwater, precipitation, and runoff, but not directly from river water.