For years, Wisconsin farmers and residents in rural subdivisions in places like Kewaunee County have pointed the finger of blame at each other when it comes to contaminated groundwater. Were coliform bacteria and nitrates in local wells coming from cows or septic systems? No one seemed to know for sure, and as a result, no one took action, and the problem got gradually worse. Now, however, a USDA study seems to have found a definitive answer. It’s the cows. The Wisconsin Center for Investigative Journalism’s Coburn Dukehart helped to break this story.