Backwater lake section of river diorama
Illinois State Museum
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Backwater Lakes

Hundreds of backwater lakes originally dotted the Illinois River floodplain. Each spring, the river filled backwater lakes as floodwaters spilled over the natural levees. These lakes were isolated from the river channel during the rest of the year. They held standing water and had soft, muddy bottoms composed of silt and decaying vegetation.

Invertebrate animals that live in the backwater lakes include the calico crayfish, marsh ramshorn snail, grass shrimp, and giant floater mussel.

Amphibians and reptiles that live in the backwater lakes include snapping turtles, painted turtles, and frogs.

Click on the "Animals" icon to see a gallery of river animal images and information.