7/1/16 - 6/30/18
- Laura Suppes, UW-Eau Claire
This research explores sources and risk factors of nitrate contamination in private wells in Eau Claire County, Wisconsin. Nitrate is a naturally occurring compound found in groundwater, but also has anthropogenic sources. It can be harmful to human health if ingested above 10 mg/L. Nitrogen-containing fertilizers, manure, and septic tank effluent are potential sources of nitrate contamination in groundwater. For this project, 110 private wells in Eau Claire County were tested for seven indicators of agricultural contamination and three indicators of septic contamination. Data on nitrate contamination risk factors (well depth, water level, distance from agricultural fields, etc.) were also collected. Project aims were: 1) To gather and analyze data to determine trends and risk factors associated with nitrate contamination in Eau Claire County, WI; 2) Evaluate the relationship between nitrate and indicators of ag or wastewater impact on groundwater; 3) Create methods to make this study reproducible by other health departments to continue research on high nitrate in private wells in Wisconsin, and 4) Gather and analyze data to provide meaningful information for decision makers. A significantly higher average nitrate concentration in wells with agricultural indicators was found, suggesting agriculture is a source of nitrate contamination in private wells in Eau Claire County. Septic systems were not found to be a significant source of nitrate in Eau Claire County. Using this analysis method, the results suggest atrazine is the most appropriate agricultural indicator of nitrate contamination in corn-dense regions where atrazine use is not prohibited. None of the risk factors hypothesized to have associations with nitrate contamination in private wells did except casing depth. Eau Claire County has 12% more private wells above the USEPA nitrate drinking water MCL than the state of Wisconsin, suggesting there is a nitrate contamination problem in Eau Claire County private wells. Direct action is needed to protect homeowners from the adverse health effects associated with consuming water with nitrate ≥10 mg/L.