Surface water input to karst springs: Comparison of methods for identifying surface influences and spring vulnerability

Karst springs and aquifers are generally considered to be highly vulnerable to contamination but this is not equally true in all cases. The degree to which surface contamination impacts a karst aquifer depends on the nature of recharge (sinkholes vs. dispersed infiltration), the type of subsurface transmission (conduit, fracture or matrix), how much storage water exchanges with newly-introduced water, and the type of contamination. The critical first step in the identification of vulnerability is to evaluate how closely the springshed is tied to surface activities and input. In this study we compare several methods for evaluating surface connections to four springs in Monroe County, WV. The surface connection is evaluated using multiple methods: (1) the WV Dept. of Health and Human Resources microbial-based criteria for groundwater supplies under direct influence of surface water; (2) organic carbon concentrations; (3) seasonal temperature cycles; and (4) variability of carbonate geochemistry. Each spring is evaluated for each criteria and ranked from most-to-least vulnerable; the sum of the ordinal ranks provides an relative score of vulnerability. Although no spring was consistently the highest or lowest ranked for all criteria, there were general trends regarding which springs were most and least vulnerable. This comparison illustrates the importance of using multiple means for evaluating the vulnerability of spring waters from surface impacts.