Sedimentation is high, and backwater lakes on the river have lost much of their depth.
Barge traffic and manipulation of water levels below the dams complicate the ecology of this watershed. When road building runs into wetlands, the law requires restoration or replacement. The Illinois Department of Transportation depends on the Surveys to assess the biology and hydrogeology of wetlands, then predict the impacts of roadways on these vulnerable sites. Multiyear projects are active at 35 sites throughout the state, including Champaign, Clinton, Du Page, Lake, Marion, McHenry, Will, Perry, and the Metro-East St. Louis counties. The concern is to avoid building over, or polluting, the natural resources so valuable for today and the future.