Sediment sources analysis For Peoria Lake along the Illinois River Bhowmik, N. G., W. C. Bogner, and J. A. Slowikowski. 1991. Sediment sources analysis For Peoria Lake along the Illinois River. In Proceedings of the 1991 National Conference of the American Society of Civil Engineers, Nashville, Tennessee, July 29-August 2, 1991. Reprinted by the National Biological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, March 1994. LTRMP 94-R006. 6 pp. (NTIS #PB94-176344) ABSTRACT The modern-day lower Illinois River flows within a greatly oversized valley formed by an old course of the Mississippi River and glacial outwash events. As a result, the section of the Illinois from its mouth near Grafton to Henry, Illinois is characterized as a low-gradient, aggrading bed stream with large backwater areas. Sedimentation in the river threatens to convert the system from one of river/backwater areas to one of channel/marshes. The sediment budget of Peoria Lake, a major backwater lake along the river, includes input and output through the Illinois River and inputs from several small direct tributaries. Results after two-year monitoring of these small tributaries indicate that they are a significant factor in the sediment budget of Peoria Lake. KEYWORDS Peoria Lake, Illinois River, sediment, sediment source tributary, suspended load, bed load