cbec conducted a feasibility study, on behalf of Florida Fish and Wildlife Conservation Commission, to investigate the dynamics of sediment transport / deposition in the main channel of the Apalachicola River, Swift Slough and the Chipola Cutoff.

The hydrologic connectivity of Swift Slough has been reduced by the incision of the main channel generally as a result of decreased sediment supply from the Jim Woodruff Dam and locally by historic navigation and maintenance activities (dredging and spoil disposal) that have been performed by the U.S. Army Corps of Engineers. Since the mouth of Swift Slough is located 1.3 miles downstream of the Chipola Cutoff (a natural area for sediment deposition) and is in the vicinity of significant dredge disposal sites that serve as a local sediment source, the deposition of sediment into the slough during high flow events has further reduced its hydrologic connectivity during low flow periods. Swift Slough has been established as the primary habitat on the Apalachicola River System for several threatened and endangered (T&E) mussel species. Its hydrologic connectivity to the mainstem of the river during low flows periods (< 6,500 cfs) is essential to the long-term viability of these species. The study involved the collection of water surface elevation data, sediment transport data, and bathymetric survey data that was used to develop a 2-dimensional hydrodynamic sediment transport model. This model tested the feasibility of three design alternatives and determined how long each alternative would promote a hydrologic connection to Swift Slough through an improved understanding of sediment dynamics within the project reach. The study results were used in the selection a preferred design alternative that improved the hydrologic connectivity of Swift Slough during low-flow periods in a manner that minimized future maintenance needs, while maintaining the habitat characteristics essential to the viability of T&E mussel species that inhabit Swift Slough.