UNDERSTANDING WAKULLA SPRING

An exceptional spring exists at Wakulla Springs State Park in Wakulla County, Florida, where a navigable river rises from depths exceeding 100 m, via a massive conduit. In addition to being a unique natural resource worthy of protection, this spring has several unusual features of scientific interest. The main conduit feeds water to the spring from the south, directly opposite to the regional gradient and flow. The water emanating at the spring has nearly a constant temperature year-round, indicating an old and deep source. However, the water, which is usually very clear, turns dark within several days following a significant rainfall. Also, the spring is very flashy, with variations on many timescales. Small variations in temperature are positively correlated with discharge; a lunar tidal signal is seen in both discharge and temperature (on a scale of hundredths of a degree).

In this presentation we will describe our plan to determine the source waters of Wakulla spring, using water as a tracer. Specifically, time-series measurements of discharge will be correlated, using wavelet analysis, with the data on rainfall in Wakulla and Leon counties. Currently we have five years of discharge data taken in the main vent. Further, with funds provided by the Florida Department of Environmental Protection, a set of meters has been purchased and soon will be placed at strategic locations in the conduit system by volunteer divers of the Woodville Karst Plains Project. Access to these meters for power and data acquisition will be provided by a set of boreholes drilled into the conduits. The first such borehole was successfully drilled on October 14, 2003.