Chapter 8C: St. Lucie and Caloosahatchee River Watersheds Annual Report
2019 South Florida Environmental Report – Volume I Chapter 8C Chapter 8C: St. Lucie and Caloosahatchee River Watersheds Annual Report Cassondra Armstrong, Fawen Zheng, Anna Wachnicka, Amanda Khan, Zhiqiang Chen, and Lucia Baldwin SUMMARY A description of the estuaries and the river watersheds is followed by a summary of the conditions of the hydrology (rainfall and flow), water quality (salinity, phosphorus, nitrogen, and chlorophyll a [Chla]), and aquatic habitat (oysters and submerged aquatic vegetation [SAV]) based on results of the Research and Water Quality Monitoring Programs (RWQMPs). Following the summary for each estuary, significant findings during the Water Year 2018 (WY2018; May 1, 2017–April 30, 2018) reporting period are highlighted. In addition, the St. Lucie and Caloosahatchee river watersheds’ water quality monitoring results for total phosphorus (TP) and total nitrogen (TN) by basin are presented in Appendix 8C-1 of this volume as supplemental information. ST. LUCIE ESTUARY WY2018 total annual rainfall across the Tier 1 Contributing Areas (Lake Okeechobee, St. Lucie Basin, and Tidal Basin) to the St. Lucie Estuary (SLE) was more than the long-term average from WY1997 through WY2018. Although 74% of the annual rainfall usually occurs in the wet season, this value increased to 80% in WY2018. The relatively high amount of wet season rain was the driver for increased discharge to the SLE. The total annual freshwater inflow to the SLE in WY2018 (1.6 million acre-feet [ac-ft]) was higher than the long-term average of 1.0 million ac-ft. The inflow and percent contribution from Lake Okeechobee in WY2018 (0.6 million ac-ft and 37%, respectively) were greater than the long-term averages (0.3 million ac-ft and 26%, respectively).
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