The Illinois River is a large river ecosystem that runs entirely within the borders of the State of Illinois. The lower two-thirds of the river is the ancestral course of the Mississippi River, and, before glaciers changed the larger river’s course, it created a wide floodplain between limestone bluffs. When the smaller Illinois River assumed its current course, large areas of connected backwater lakes survived to foster abundant plant and animal communities.

The Illinois River has provided human communities with drinking water, natural resources, commercial river navigation, and served later to provide recreational opportunities for fishing, hunting, and boating. It once was a vibrant system, providing the nation with fish, waterfowl, and other commercial products, and was considered the second largest freshwater fishery in the United States. Man-made alterations to the floodplain, watershed, and the river itself, along with various forms of pollution, changed this resource and the legacy of these changes can be observed today.

The most significant impact and a dire threat to this system is the accumulation of sediment in the backwater lakes and in the river channel itself. Where many of these areas were six to eight feet deep in 1903, today most areas are less than two feet deep. Many backwater areas have vast acres of exposed mud flats in low water conditions. If action is not taken today, many of these areas will be lost to encroaching terrestrial plants and will not be easily reclaimed.