Survey of marine wetland and estuarine water quality and ecological problems in Corps of Engineers field offices
Abstract: This report presents the results of a survey of Corps of Engineers (CE) field offices that have coastal zone responsibilities. The purpose of the survey was to investigate existing or anticipated water quality .and ecological problems associated with CE activities in marshes and estuaries. Emphasis was placed on identifying those problems amenable to analysis through application of predictive modeling techniques. The identified problems represent the perceptions of the field personnel as interpreted by Science Applications, Inc. In some cases, perceived problems have been extensively researched or are being presently studied. The survey was designed to identify problems perceived by the field offices and may not reflect current understanding. Three general problems were emphasized by all offices: (A.) the uniqueness of the specific environments in their District; (B.) water quality and environmental problems are functions of local concerns of the public; and (C.) there is a need to evaluate effects of a change in physical regime on an estuary. Specific problems identified are summarized below: (1.) Techniques are needed to predict the effects of Corps of Engineers activities on the hydrodynamics, dissolved and particulate transport, biological and chemical processes, and biota in coastal environments. Corps of Engineers activities include construction, channel deepening and widening, island creation and upstream projects leading to changes in freshwater flows. (2.) Selected marsh/estuarine areas need to be characterized in terms of physical, chemical, and biological structure and chemical and biological processes. Specific areas identified include the east and northeast coasts, infrequently flooded marshes, mangrove swamps, and buffer areas such as the saline flatlands of the western gulf. Included in the characterization would be a uniform methodology of classification and a means to assess the value of the wetland to the total ecosystem. (3.) The types and magnitudes of stresses the marsh/estuarine ecosystem may be subjected to in terms of structural stability and deviations in the rates of selected chemical and biological processes need to be determined. Included would be estimation of the assimilative capacity for effluents from diked impoundments, dredged material disposal sites, storm runoff, and agricultural runoff. Indices of structure and processes include fish and invertebrate nursery grounds, fish production, water quality, and import/export relationships of nutrients and detritus. (4.) Techniques to evaluate the cumulative impacts of dead-end canals, small boat harbors, and marinas on the adjacent coastal ecosystem need to be developed. Procedures are needed to assess the magnitude of perturbations of water quality due to point and nonpoint sources of contaminants entering the canals and small harbors. Design criteria to minimize adverse water quality degradation within the canals and harbors and in the adjacent ecosystem need to be formulated. (5.) An increased understanding is needed of the process of marsh creation through deltaic growth including habitat creation and species succession. (6.) Existing hydrodynamic models need to be extended by including selected water quality parameters in advection-dispersion equations. Priority of inclusion is salinity, temperature, dissolved oxygen, nutrients, phytoplankton, and toxicants.
Environmental Laboratory (U.S.)
Coastal zone management; Wetland conservation; Estuarine area conservation; Water quality management