Long Term Resource Monitoring Program 1993 Flood Observations National Biological Service, Illinois Natural History Survey, Iowa Department of Natural Resources, and Wisconsin Department of Natural Resources. 1994. Long Term Resource Monitoring Program 1993 Flood Observations. National Biological Service, Environmental Management Technical Center, Onalaska, Wisconsin, December 1994. LTRMP 94-S011. 190 pp. (NTIS #PB95-181582) ABSTRACT During the 1993 flood on the Upper Mississippi River System (UMRS), observational information was obtained by State and Federal agencies participating in the Long Term Resource Monitoring Program (LTRMP). The LTRMP is managed by the National Biological Service, with additional oversight provided by the U.S. Army Corps of Engingeers. The data summarized in this report focus on physical, chemical, and biological conditions occurring during the flood. Pre-flood data obtained through earlier LTRMP monitoring efforts provided (in some cases) a basis for evaluating preliminary observations made during the flood. In general, it appears that the species composition and distribution of aquatic and floodplain vegetation may have been significantly altered, at least over the short term. In some areas, historical patterns of sediment deposition/erosion may also have been altered. Water quality conditions during the flood were quite variable and were probably transitory. Over brief periods of measurement in 1993, the density and species richness of fish and invertebrate communities appear to have been influenced by flooding. For the most part, effects of the 1993 flood on the ecology of the UMRS are still unfolding. Thus, definitive conclusions at this time regarding flood effects are not possible. The purpose for compiling the information contained in this report is to provide a substantive basis for future reference. KEYWORDS Mississippi River, water quality, sediment, fish, aquatic invertebrates, aquatic plants, floodplain, flood