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258 J. R. SHUMAN significant portion of the information necessary for preparing an EIS. At the time this paper was written, all the research efforts listed in Table V were still underway. Consequently, a decision on dam removal had not been made at that time. The following describes the intent of these various research efforts and their importance in an overall assessment of the dam retention and removal alternatives. The river transect surveying project (Table V) will provide the baseline elevation data necessary for the hydrological and hydraulic modelling. Hydrological and hydraulic modelling results are necessary to assess river flow dynamics during and following dam removal, and to assess reservoir water level management options under the reservoir retention alternatives. Bathymetric and sediment depth mapping will provide the data required to develop drawdown scenarios for either dam removal or reservoir management. Sediment depth data are necessary to calculate the volume and mass of sediments accumulated in the inundated floodplain which might be resuspended or entrained during a drawdown and potentially transported downstream. Sediment transport modelling will provide predictions not only on the amount of sediment in the river channel which would be transported downstream and where it would likely be deposited, but will also assess river channel stability following dam removal. This is critical for Rodman Reservoir because the CFBC, which was dredged to a depth of 3-0m, intersects both the main river channel and tributaries to the Ocklawaha River. The water quality assessment project will provide data on river and impoundment water quality to describe the existing environment and to form the baseline for predicted changes to water quality as a result of sediment transport during drawdowns and dam removal. The impacts of a complete drawdown for dam removal on groundwater levels will be assessed, including effects on water levels in residential wells, discharge from springs and water levels in nearby lakes and wetlands. The inundated floodplain analysis project will provide information on the nature of the inundated floodplain and the physical and chemical characteristics of its sediments. An assessment of whether toxics and other pollutants are present in the sediments, and their risk if resuspended into the water column and transported downstream, will also be performed. The physical characteristics of the sediments, including particle size composition, critical sheer stress, settling velocity and erosion rate, will be measured to estimate the resuspension potential of these sediments during a drawdown. Nutrient concentrations and the density of sediments will also be measured and coupled with sediment resuspension and sediment transport predictions to calculate potential downstream nutrient and sediment loading. The seedbank in the floodplain sediments will also be assessed to predict the initial plant species inhabiting the exposed floodplain soils after drawdown. As much of the floodplain forest was simply pushed into the soil by large `tree crushers' when the reservoir was constructed, we will utilize divers to videotape the inundated floodplain. This will help determine the extent of coverage of the inundated bottom by downed trees, which may influence revegetation characteristics if the river is restored. Fish populations, including migratory fish, will be monitored in both the reservoir and in the river both upstream from the reservoir and downstream from the dam (Table V). These data will complement historical information to assess current conditions, historical trends and to predict fish populations and migratory fish usage of the river and reservoir under the four alternatives. The bird communities in both the river and reservoir are being surveyed to determine species composition and density. Information on threatened and endangered species and species of special concern is being reviewed, and additional surveys for particular species are being performed to assess both the positive and negative impacts under the four alternatives. Other species of wildlife are also being considered through reviews of existing information. Aquatic plants, especially Hydrilla verticillata, are typically dense in the reservoir and inhibit the free movement of boats. These aquatic plant populations will be surveyed to provide current information on coverage, and control and management strategies will be developed for the reservoir retention alternatives. The assessment of habitats (Table V) will describe past, current and future ecological habitats in the river and reservoir sections of the Lower Ocklawaha basin. The impact of habitat fragmentation by the reservoir on wildlife movements will be addressed. Historical vegetation communities will be described from photogrammetric interpretation of historical aerial photography before reservoir construction. Similar photogrammetric interpretation will be performed from current aerial photography. Under the partial dam retention and both river restoration alternatives (i.e. dam removal), predictions will be made