Pool 25: Water level alternatives and their effects on habitat Wlosinski, J. H., and J. Rogala. 1996. Pool 25: Water level management alternatives and their effects on habitat. National Biological Service, Environmental Management Technical Center, Onalaska, Wisconsin, October 1996. LTRMP 96-T004. 85 pp. + Appendixes A D. (NTIS #PB97-134738) ABSTRACT The effects of changing levee and water level management practices on present habitat types and amounts on the Upper Mississippi River floodplain at Pool 25 were predicted. The intent of the study was to investigate a broad range of plans that would provide coarse resolution information and the tools needed to study specific plans in the future. Two conditions were investigated for levees: the present levee system and all levees removed. Five water level management plans were studied: the present plan, two plans that would increase water levels, and two plans that would decrease water levels. The levee and water level management variables resulted in a total of ten unique management alternatives. Each was studied at four discharge regimes for a total of 40 scenarios. A geographic information system (GIS) was used to investigate the amounts and types of habitat that would be affected for each scenario. Tools developed for the study were a discharge elevation relation for the tailwater of Pool 25; estimates of water levels throughout Pool 25 for each scenario; GIS coverages of water levels, floodplain elevations, levees, and habitat types; and a technique to compare alternative scenarios. All GIS analyses were performed in a raster environment. KEYWORDS Discharge, GIS, habitat, habitat changes, land cover, levee, Mississippi River, Upper Mississippi River, water level