Recharge area delineations and hazard and vulnerability mapping in Perry County, Missouri

Eight recharge areas have been delineated in the sinkhole plain of Perry County, MO, USA. The groundwater systems delineated were the Moore Cave system, Keyhole Spring, Ball Mill Spring, the Crevice Cave system, the Mystery Cave system, the Rimstone River Cave system, Thunderhole Resurgence, and Running Bull Cave. These systems include four of the five longest caves known in Missouri and two of the top four in having the most globally rare species. The delineations were done in support of the grotto sculpin ( Cottus specus ) which is a fish adapting to cave environments, and because these cave streams seem to be the source of impairment in their receiving streams. Seventeen springs, including overflow springs, are associated with these groundwater systems. The results of a total of 87 dye introductions were used to complete the delineations, and the sampling network included 93 sampling stations. The tracing showed that the Mystery Cave system overflows to several springs under high flow conditions. Almost 94 km 2 of land were included in the delineations. Hazards and vulnerability were also mapped. All of the recharge areas have potentially ineffective private septic systems, agriculture without universal application of best management practices, roads with poor water quality runoff and the threat of spills, and sinkhole dumps. The Crevice Cave system recharge area also has the City of Perryville, numerous underground storage tanks, and several facilities with national pollutant discharge elimination system (NPDES) permits, and hazardous waste generators, making it the least likely system to be a practical target for conservation. All of the recharge areas were mapped as highly vulnerable due to the rapid recharge of groundwater through discrete karst features. The data generated from this investigation can be used to direct efforts to conserve the grotto sculpin and improve water quality in the cave streams and in their receiving streams.