Date Time Arsenic is more common in wells near fractured bedrock in southeastern Wisconsin Wells located near ancient folds and fractures in the bedrock beneath southeastern Wisconsin are more likely to contain arsenic, a dangerous contaminant in drinking water, according to research just published by the Wisconsin Geological and Natural History Survey. The findings come from an ongoing survey of the extent and causes of arsenic contamination in groundwater in eastern Wisconsin. By better predicting where arsenic will be found, the project could help municipalities and private well owners relocate or redesign wells or prepare to filter out the arsenic, which can cause cancer if ingested over time.