Cows or People? Fecal Sources and Risk Factors Associated with Private Well Contamination in Northeastern Wisconsin
Dr. Mark Borchardt, Research Microbiologist for the USDA – Agricultural Research Service and Program Leader for the Laboratory for Infectious Disease and the Environment
Monday November 26
12 – 1 pm
27 Cryeke Road, Ilam
The quality of the Silurian dolomite aquifer in northeast Wisconsin has become a contentious issue as dairy farms and exurban development expand. During groundwater recharge in the spring, “brown water” events (i.e., fecal contamination events) prevent homes from having access to clean water. We addressed two questions: 1) What is the primary fecal source of well-water contamination, cattle or people? 2) Which risk factors (land use, meteorological, hydrogeological) are associated with well contamination events. Land use practices surrounding each study well (e.g., number of septic systems, acres of agricultural fields,) were obtained from GIS layers managed by local governments. Meteorological data (e.g., precipitation) were provided by NOAA radar estimates and on-the-ground measurements. Groundwater recharge was calculated by the water-table-fluctuation method using data from a local monitoring well. Well construction data (e.g. casing depth, well age) were abstracted from reports filed at the Wisconsin Geological & Natural History Survey. Associations of risk factors with 1) the probability of well contamination; and 2) well concentrations of microbial contaminants were evaluated by logistic and gamma regression models, respectively. Agricultural-related land uses such as the acreage of agricultural fields within 3,000 feet of a well or the proximity of manure pits are important risk factors. Groundwater recharge and depth-to-bedrock are also important. This information is useful for developing policies to minimize contamination of private wells in the fractured dolomite aquifer.
Dr. Mark Borchardt is a Research Microbiologist for the USDA – Agricultural Research Service and Program Leader for the Laboratory for Infectious Disease and the Environment, US Geological Survey, Upper Midwest Water Science Center. Dr. Borchardt’s expertise is on the measurement, fate, transport and health effects of human and agricultural zoonotic pathogens in the environment. Recently, he received the Dr. John L. Leal award from the American Water Works Association for his work on improving water quality and protecting public health in the United States.
Waterways Center for Freshwater Management
University of Canterbury and Lincoln University
Monday – Friday 9 – 3, Wednesdays at Lincoln
369-5834 UC, 423 4050 LU