Designing large-scale wetland restoration for Delaware Bay

Perimeter dikes around Delaware Bay salt marshes, many installed more than 50 years ago, have reduced marsh plain elevations, obliterated tidal channels, reduced Spartina alterniflora and increased Phragmites australis. Restoration goals included a salt marsh ecosystem dominated by S. alterniflora with significant areas of Spartina patens and to increase the detrital production and contribution of these areas to the marsh/estuary food web and to provide refuge, feeding habitat, and nursery grounds for various estuarine fish. The first step in the design process was to obtain consensus among regulators, ecologists, engineers, and the public as to marsh structure and function. Second was to reach agreement on the essential sedimentary and hydrodynamic characteristics needed to achieve the desired ecosystem. Third was to develop a two-dimensional hydrodynamic numerical model to design marsh channels that would not erode, would have typical channel cross-sections, and would have a hydro-period on the marsh plain to allow growth of the desired species. The process for design that met the restoration goals and was acceptable to the regulatory agencies and the public was complex. We discuss the social/political and the scientific/engineering steps used to reach a final design acceptable to all involved parties.