During the last decade, Florida Bay has experienced ecological deterioration that has been partly attributed to an increase in salinity. Salinity is directly related to the amount and quality of water that enters Florida Bay from the mainland and to flow patterns within the Bay. Restoration of the Florida Bay ecosystem requires a better understanding of the linkage between the amount of water flowing into the Bay and the salinity and quality of the Bay environment. As sheetflow is reestablished by flow management in the wetlands of the Everglades, it is expected that these changes will be reflected in the amount of water exiting the mainland through the principal streams or as sheetflow into Florida Bay. Several agencies, including the U.S. Geological Survey, U.S. Army Corps of Engineers, and the South Florida Water Management District, are now developing and calibrating models to simulate and predict the movement of water in the mainland, flows in to Florida Bay, and circulation patterns within the Bay.

The U.S. Geological Survey is conducting a study to determine flows into northeastern Florida Bay. This study will provide essential flow and salinity data for models along the mangrove zone, where data have not been previously available. Flow through the mangrove zone in northeastern Florida Bay is naturally controlled by the wet and dry conditions of the Everglades wetlands, regional wind patterns, and, to some extent, by tidal action in the Gulf of Mexico toward the western part of the Bay. The flow of water from the mainland into northeastern Florida Bay is confined to several streams or creeks, except during extreme high-water conditions, when significant sheetflow can be observed through low-lying mangrove areas between the streams. Acoustic technology is being used to determine the flows in streams that discharge water into Florida Bay.

Ten sites located between U.S. Highway 1 to the east and Terrapin Bay to the west are being studied in northeastern Florida Bay in Dade and Monroe Counties. These sites are: Jewfish Creek, culverts under U.S. Highway 1, East Highway Creek, West Highway Creek, a small unnamed creek in Long Sound, Trout Creek, Mud Creek, East Creek, Taylor River, and McCormick Creek. Velocity and water-level data collected from the sites indicate that flows through creeks draining into northeastern Florida Bay are greatly affected by regional wind patterns and do not present tidal signatures typical of most estuarine streams. Salinity data indicate that, at times, there is a vertical stratification; however, this does not occur frequently nor does it last for extended periods of time. Analysis of discharge data suggests that low-pass filters, commonly used to calculate "net flows" by smoothing the tidal effects, are not suitable for use at these sites, given the "noisy" flow patterns. Further study of the effects of wind and the "storage" factor of uplands is needed to better understand the flow system along the mangrove zone of northeastern Florida Bay.

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