Assessment of Upper Taylor Slough water quality and implications for ecosystem management in Everglades National Park

This study addresses water quality conditions across several distinct hydrologic regimes in the Upper Taylor Slough (UTS) region of Everglades National Park and briefly considers implications for long-term water quality management. Due to upstream changes in water delivery and construction of a detention area, Taylor Slough has experienced a significant change in hydrology over a 27-year period, progressing from direct discharge at varying amounts to sheet flow via groundwater conditions. Cumulative flow and rainfall relationships at the inflow and outflow of UTS demonstrate distinct break points. These changes in water delivery and subsequent upstream water management have resulted in a change in water quality conditions within the UTS region. Since 1986, total phosphorus (TP) flow-weighted mean concentrations exiting UTS have significantly decreased from 10 µg/L in the late 1980s to 4 µg/L or less since 2010. Based on analysis of surface water ion ratios, saltwater intrusion is unlikely and rather hyporheic exchange could be occurring between the inflow and outflow of the UTS region. Based on the analysis of existing water quality data, the UTS region is a resilient oligotrophic wetland system retaining strong assimilation capacity in the face of major management changes. While TP concentrations remain extremely low, restoration is not complete for Taylor Slough and adjacent coastal basins will inevitably bring additional nutrient loading. Management of the Slough should recognize this and consider what water quality condition is best for long-term sustainability of Taylor Slough’s ecology.