Cows and People Can Pollute Groundwater
In a new study of ground water pollution in northeast Wisconsin, both cows and people can be to blame for bacteria reaching water wells, reports the Milwaukee Journal.
The study, done in Kewaunee County on the peninsula jutting into Lake Michigan northeast of Green Bay, was done in an area of high dairy cattle concentration, lots of homes and topography unique to that part of the state. The county has fractured bedrock that is often overlain by a shallow layer of top soil.
Study results suggest human septic systems tend to be a constant source of contamination while manure from cows tends to seep into groundwater following rain events. The study, done in April, August and November, pulled water samples from 82 homes. Bacteria from cows was found in 26 wells and bacteria from humans was found in 18.
In April, 11 samples were traced to humans while five came from cows. In August, six samples came from humans while another five came from cows. But in November, after a huge rain event (and likely after manure was applied to land), 16 samples were traced back to cattle while just one came from humans.