Cooperative water quality testing and vulnerability factors for private rural wells in Central Indiana

A cooperative well-testing program was implemented in a 10-county region of central Indiana to determine the nature and extent of rural well contamination by agricultural chemicals. The program relied on volunteers and local officials for administration, and on individual owners of residential wells for collection of water samples and completion of questionnaires about well-vulnerability factors that could contribute to contamination. A total of 2,252 well-water samples was analyzed for total nitrogen, triazine, and alachlor. Drinking water from wells in the area had lower concentrations of total nitrogen, alachlor, and triazine than have been found in federal, nationwide, and various individual-state studies. Wells situated in sandy soils, as well as older and shallower wells, had elevated concentrations of nitrogen and pesticides. Dug wells had higher concentrations of contaminants than driven wells, and drilled wells were least prone to contamination. Close proximity of wellheads to cropland and feedlots also increased the likelihood of nitrogen and pesticide detection in well water. Like previous cooperative well-testing systems, this program provides extensive spatially-distributed data to state and local governments and allows comprehensive regional assessments of groundwater quality. Rural environmental health professionals can use the findings to educate well owners about factors that affect likelihood of contamination.