Sampling Purpose: The Illinois State Water Survey (ISWS) designed a project to characterize the conditions of selected backwater lakes in Illinois after the 1993 flood and to evaluate whether or not the flood affected the sediment deposition rate and pattern in the lakes. Sediment core or grab samples were obtained from 5 backwater, were dated by Cs-137 decay, and analyzed for carbon (total, organic, and carbonate) and metals. All sediment samples were analyzed by the Illinois State Geological Survey (ISGS) lab for the purpose of comparing results with previous ISGS studies on the Illinois and Mississippi Rivers. Each sediment sample was analyzed by four different methods (x-ray fluorescence spectrometry, atomic absorption spectrometry, energy dispersive x-ray fluorescence spectrometry, and photographic optical emission spectroscopy). The data from all four methods are presented in the database, to illustrate that different contaminant concentrations can result depending upon the rigor of the digestion method. Additional or split sediment samples were also analyzed at the Illinois Environmental Protection Agency-certified ISWS chemistry laboratories (refer to data set no. 40). Sample coordinates were not provided with this study; however, coordinates were approximated in ArcView using detailed maps and descriptions of sampling sites.