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Savannah Harbor Dredged Material Containment Areas
Savannah Harbor, Jasper County, South Carolina, United States
The Savannah Harbor Navigation Project’s (SHNP) Dredged Material Containment Areas (DMCAs) are confined disposal facilities for dredged material. The material is collected by the U.S. Army Corps of Engineers (USACE) Savannah District (SAS) on an on-going basis during Savannah Harbor maintenance operations and from SHNP activities currently underway in Savannah, Georgia. The DMCAs are managed to mitigate for lost wetland habitat that results from these USACE activities in the Savannah Harbor and for modifications to the DMCAs themselves. A long-term management strategy (LTMS) was developed to maintain specific quantities of wetland and openwater habitat to benefit seasonal waterbirds. A series of five DMCAs are subject to a deposition of dredged material rotation program; some DMCAs receive the material for a period of three years while other DMCAs remain dry. This rotation pattern serves to create open water habitats for waterfowl and other waterbirds on the DMCAs receiving dredged material, while mudflat and wetland habitats are available for shorebirds on the dry DMCAs. The rotation approach also promotes settling of material that helps extend the life of individual DMCAs. Additional material can be added to enhance levees around those DMCAs scheduled to receive dredged material. Four- and eight-acre islands created in the DMCAs provide nesting habitat for numerous shorebirds and colonial waterbirds.
Cover photo: American white pelicans are frequent users of the DMCAs. (Photo by Stevan Calver, USACE Savannah District [retired])
Producing Efficiencies
Engineering and construction of the DMCAs in the Savannah Harbor increases efficiency of maintenance dredging operations by providing nearshore dredged material disposal options. Open water and wetland habitats provided by the DMCAs serve to meet mitigation compliance requirements and allow for the ongoing operational efficiency of local and regional operations. A series of five DMCAs are on a rotation schedule to receive dredged material. The DMCAs receiving dredged material function as open water habitat for waterfowl and other waterbirds, while dry DMCAs serve as mudflat and wetland habitat for shorebirds.
Using Natural Processes
Due to human development, the meandering nature of the Savannah River has diminished and coastal sedimentation processes have been impaired. The result is lowered availability of shallow open water and wetland, mudflat, sandspit, and island habitats. The LTMS maintains a rotation schedule for dredged material disposal operations that has been successful in maintaining year-round availability of over 200 hectares of open water and 260 hectares of wetland/ mudflat habitats. Consequently, LTMS maintains habitat that would have been available if there were no human development in the area. In addition, islands created with dredged material in the DMCAs provide avian breeding sites that are separate from the mainland and that offer some protection from mammalian predators of shorebirds and colonial waterbirds.
Broadening Benefits
The construction of the DMCAs and the implementation of the LTMS increase the social and economic benefits provided to the local, regional, and national economies by enabling important harbor and port infrastructure construction that promotes national and international commerce. Long-term monitoring of the seasonal waterbird communities from 1994 to 2012 revealed that the DMCAs provide important habitat to many regionally identified waterbird species of concern, including state- and federal-listed species, such as the least tern.
Promoting Collaboration
During construction of the DMCAs and implementation of the LTMS, USACE Savannah District personnel consulted with state and federal agencies, such as the U.S. Fish and Wildlife Service (USFWS) and the National Marine Fisheries Service, to ensure incorporation of all stakeholder concerns. The USFWS approved the final mitigation plan and provided input about and approval of the seasonal avian community monitoring effort.
