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Florida Lake Management Society Annual Conference, Naples, Florida, June 4 – 7, 2007

absorbed by soils. Compounds like Nitrate and Chloride behave differently, they are hydrophilic and percolate through the soils without attenuation.


Atmospheric deposition studies indicate that oxidized nitrogen does not have a major effect on groundwater nitrate nutrient concentrations. Phosphate deposition was insignificant because the sandy soils contain enough clay for the soil water equilibrium concentrations of phosphate to dominate groundwater concentrations. Septic tank systems did not have dramatic effects on the surficial aquifer Mesocosm experiments indicate that approximately 50% of the nitrogen was attenuated and phosphorus was completely attenuated. Dye studies, some covering over 16 miles, showed that open karst features transport surface water directly into area springs. Background water comes from across the Georgia border. Extensive conduit systems in the central and western WRB carry nutrient rich water to Wakulla Springs. Nitrogen is largely derived from a wastewater sprayfield and phosphorus from sinking streams and lakes. Extensive conduit systems in the eastern WRB carry the waters that are low in nutrients to the St. Marks Rise. This area is relatively undeveloped. Stormwater flows into Sinkholes from Karst Lakes and Sinking Streams and passes directly to the aquifer without being attenuated. Deep wells indicate that groundwater flow may be facilitated in the WRB by a dipping impervious dolomite layer between 100 and 200 feet. A rubble zone above the dolomite behaves as a pseudo conduit. Saline waters were encountered at depths of 300 feet within the WRB. Lake Jackson, May 2007

This Study was funded by the U.S. Environmental Protection Agency. Greg Mauldin (Tallahassee-Leon County GIS), Frank Lesesne, PG. (MACTEC) and Steve Reese, PE. (Ardaman) contributed to this report.


Session 8B – Page 6

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