Hydrologic Conditions in West and Seven Palm Lake Drainage Systems in the Florida Everglades

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A major component of the Comprehensive Everglades Restoration Plan is to enhance the management of freshwater delivery to Taylor Slough and ultimately northeastern Florida Bay, in an effort to restore a salinity regime necessary to support the local ecosystem.  The additional freshwater deliveries may also benefit a system of interconnected lakes, creeks, and wetlands located to the west of southern Taylor Slough that are also connected to Florida Bay. The research presented here is being conducted in the mangrove lakes region bordering Florida Bay, west of Taylor Slough. The lakes comprise two distinct drainage systems; the Alligator Creek (West Lake) System and the McCormick Creek (Seven Palm) System. In order to understand the impacts of restoration efforts and natural change in this region, current hydrologic conditions must be established. A possible hydraulic connectivity between southern Taylor Slough and the mangrove lakes region to the west via overland flow and/or groundwater flow may provide additional unforeseen benefits of current restoration efforts to improve the drastically diminished water quality in this region.

Preliminary data for this study suggests that the McCormick Creek drainage system to the east has a much greater fresh groundwater delivery than the Alligator Creek drainage system to the west. In addition, total phosphorus concentrations in the surface waters of the McCormick Creek system (<1 µM) are far less than those of the Alligator Creek system (1 – 6 µM). Brackish coastal groundwater discharge in this region has been shown to be enriched in total phosphorus, suggesting that increasing sea levels and reduced freshwater inflows are having a great effect on the Alligator Creek system (Price et al. 2006; Price et al. 2010). Surface water and groundwater salinities vary seasonally in this region, although groundwater salinity in each of the lakes in the Alligator Creek system is consistently higher than surface water salinity, regardless of season. Further investigations within this project include the use of geochemical tracers to determine groundwater – surface water interactions and complete water balance calculations for each drainage area on a daily, weekly, monthly and annual basis. The suite of techniques used within this study will provide a complete understanding of the current hydrologic conditions in this region, which will be used to determine the ultimate impacts both sea level rise and restoration present to the lake systems.