NOTE: The complete SWIGG survey is available on the Midwest Farm Report’s news feed.
Rural residents from Wisconsin’s southwestern counties rely on private wells for their water. Contaminants from septic systems, fertilizer, and manure can contaminate the groundwater that residents use, and a Wisconsin survey of private wells showed how land use, geology, and construction can also affect drinking water quality.
The Southwest Wisconsin Groundwater and Geology (SWIGG) study tested 978 samples from 816 private wells across Grant, Iowa, and Lafayette counties. 32% of the private wells sampled in 2018 and 2019 tested positive for total coliform bacteria and/or nitrate greater than the Wisconsin and EPA health standard of 10 mg nitrate-nitrogen per liter.
This study sought to identify the causes of contamination, not just the presence of it.
Ken Bradbury, Director and State Geologist for the Wisconsin Geological and Natural History Survey, helped conduct the SWIGG survey, which he says is one of the most comprehensive studies of this type ever done in the US.
He says he was not surprised by the results of the study, which indicated the presence of human, cattle, and swine fecal matter in select private wells across Southwestern Wisconsin. The contamination varies across all three counties that were tested, and was not limited to just one spot or area.
Bradbury attributes the presence of contamination to the condition of the wells in the area. They found that the older the well, and the more shallow the well, the more likely it is to be contaminated. He says the bottom line is if you are a homeowner, pay attention to your surroundings, as all three forms of fecal contamination can get into groundwater.
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