CHARACTERIZATION OF A KARST SPRING LOCATED IN NORTH-CENTRAL, ARKANSAS

The Ozark cave crayfish (Cambarus aculabrum) is a federally listed endangered species. Threats to the crayfish include development and agriculture. To help protect the endangered species, the source, extent, occurrence, and age of the waters discharging from Nesbitt Spring Cave were characterized. Nesbitt Spring, located in north-central, Arkansas, lies in the Ozark Plateau physiographic province. The hydrogeologic framework of the area comprises karst terrain; hence, the cave is highly susceptible to contamination from surface sources within and outside its surface drainage area. The spring discharges from the Ordovician-aged Plattin Limestone but is recharged through the Mississippian-aged Boone Formation. Water-quality data including temperature, conductivity, pH, dissolved oxygen, turbidity, and major ions was collected. Continuous stage was measured and a stage-discharge relationship was developed. The source, age and recharge characteristics of Nesbitt Spring were determined by the use of radioactive and stable isotopes. The waters discharging from the spring have displayed the same water-quality characteristics as other wells and springs sampled within the Boone Formation of the Springfield Plateau aquifer system. Flow is mainly conduit dominated and is concentrated along joints. The cave passage that Nesbitt Spring discharges from trends at 105º which is consistent with other measured joint sets and lineaments in the area.