New report reveals prevalence of well contamination in Iowa


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Click here to explore new findings on well contamination from the Environmental Working Group and Iowa Environmental Council. 

Julia Poska| April 25, 2019

If you own a private well in Iowa, it’s likely contaminated with dangerous bacteria, nitrates or both, according to a new report from the Iowa Environmental Council and the Environmental Working Group.

“Wherever Iowans test for these contaminants, they have a pretty good chance of finding them,” the report’s primary author, economic analyst Anne Schechinger said in a press release.

The report was released yesterday as an interactive map, using dots in three colors to indicate the relative levels of contamination between counties based on state testing from 2002 to 2017. Because the EPA does not require testing for private wells, the vast majority of Iowa’s private wells are never tested. Only 55,000 of Iowa’s estimated 290,000 wells were tested during the study period.

Over 40 percent of those wells contained fecal coliform bacteria, considered unsafe in any amount. Twelve percent had nitrate levels above the EPA’s 10 parts per million safety standard. Twenty-two percent had nitrate levels above 5 ppm, which recent studies have linked to increased risk of numerous health problems, according to the report. The average nitrate level rose to 5.7 ppm over the years of study.

Over that entire period, eight counties tested fewer than 10 wells, meaning this report tells an incomplete story. Findings indicate that those counties, which appear the cleanest on the map, may actually be among the most at risk.  Only one-third of wells were tested more than once. Those that were tested repeatedly often showed continued contamination, indicating lack of action.