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DAM REMOVAL 255 Rodman Dam was constructed on the Ocklawaha River in 1968 as part of the Cross Florida Barge Canal (CFBC) project, envisioned as a navigation corridor across the state of Florida connecting the Gulf of Mexico with the Atlantic Ocean. This navigation corridor was to consist of canals and locks interconnecting the Withlacoochee, Ocklawaha and St Johns Rivers. Construction of the canal began in 1964 with Rodman Dam and Reservoir. Buckman Canal and Lock were also constructed, connecting the St Johns River with Rodman Reservoir. Rodman Dam is an earth-filled structure approximately 6.7 in high and 2073 m long. The dam contains a concrete spillway with four bottom withdrawal gates. The reservoir is maintained at 5-5m, National Geodetic Vertical Datum (NGVD), for navigation purposes, thereby creating a 3642 ha impoundment. The lacustrine and transition zones of the reservoir have a mean depth of 2-5m and maximum depth of 9-4m. In 1971, a Federal injunction halted further construction of the CFBC. At this point, Rodman and Eureka dams and Buckman Canal and Lock had already been constructed, but only the river above Rodman Dam had been impounded. In 1991, the CFBC project was officially deauthorized. All Federal lands and structures within the CFBC project were transferred to the State of Florida in 1992. In the spring of 1993, the Florida Legislature decided that current scientific information on Rodman Reservoir and the Lower Ocklawaha River was insufficient for an accurate assessment of whether to retain Rodman Dam and Reservoir or to restore the Lower Ocklawaha River. The Legislature provided $930 000 for the St Johns River Water Management District to conduct scientific studies comparing four river restoration and reservoir retention alternatives. The four restoration and retention alternatives are: (1) full restoration-to restore river hydrology and floodplain function and remove all structures and return topography to pre-construction conditions; (2) partial restoration-to restore river hydrology and floodplain function with limited removal of structures and alteration of topography; (3) partial retention-reducing the size of the impoundment while restoring a portion of the now-impounded river; and (4) full retention-retaining the dam and reservoir with active management for fish and wildlife resources. Rodman Reservoir does not currently provide flood control, water supply or hydropower benefits. Its main economic attributes are as a recreational resource and as a navigation corridor between the St Johns River and the Ocklawaha River via the Buckman Canal and Lock. This canal lock would be unnecessary for navigation, of course, if the dam were removed. Two boat ramps, a fishing pier, walkways, parking areas and a day-use area are located near the dam. Three active recreation sites and campgrounds are located on the reservoir. Issues specific to the retention of Rodman Reservoir or restoration of the Ocklawaha River have been voiced by both retention and restoration proponents over the 25 year controversy surrounding this dam and the CFBC project. Rodman Dam blocks migratory fish runs and movements by manatees, although the significance of these impacts is unknown. Supporting claims are made by both retention and restoration proponents regarding fish and bird populations and threatened and endangered species under the four alternatives. These and other issues have been voiced at numerous public hearings. The most common environmental concerns during and following dam removal are sediment transport and floodplain dynamics (Table 111). The dam removals discussed here and in published papers attest to the potential problems related to sediment transport, particularly the Fort Edward Dam removal in which toxics and sediments were transported downstream. It should be noted that although sediment transport invariably occurs following dam removal, its severity is determined by the volume of sediments impounded by the dam and by the dam removal procedure utilized. The proposed Elwha and Glines Canyon Dam removals and the Newaygo Dam removal all utilized sediment transport modelling to predict the move- ment of sediment following dam removal (modelling was conducted after dam removal for the Newaygo Dam). Significant efforts are being expended for the proposed Elwha and Glines Canyon Dam removals to predict the extent of sediment transport and the methods for drawdown and dam removal which would minimize it (FERC, 1991). Other physical and chemical issues relevant to the removal of dams include changes to river channel morphology both above and below dams, recontouring of the floodplain to assure beneficial floodplain