More than 40 percent of private wells tested positive for coliform bacteria at least once over a 16-year period, according to a new study of Iowa state records by the Environmental Working Group and the Iowa Environmental Council. Up to 290,000 Iowans rely on water from private wells, yet the state tested just 55,000 for nitrates or bacteria during the years of the study. The report points to farm operations as a main source of the contaminants.
“There’s a clear pattern of widespread private well contamination across Iowa that is growing worse for nitrate and staying steadily bad for bacteria,” said Cindy Lane, water program director for the Iowa Environmental Council, in a press release. “But we don’t even have information on the thousands of wells that were not tested during this period. That makes me worry that the problem is even more serious than documented.”
Three-quarters of the polluted wells were located in rural parts of the state. Consuming nitrates and bacteria can lead to an array of negative health outcomes, including increased risk of cancer, birth defects, vomiting and diarrhea.
The contaminants in the wells in many cases exceeded legal limits. The Environmental Protection Agency sets the legal limit for nitrates in drinking water at 10 milligrams per liter. More than 6,600 wells in Iowa had nitrate averages at or above that level.
Testing of private wells is left to the landowner. The Iowa Department of Natural Resources recommends that well owners test their water every year, but does not require it. As a result, testing data is spare. Almost two-thirds of the private wells in the state were tested just once over the span of the study.
If their wells are contaminated, landowners must dig a new well or have their water treated—both options that can cost thousands of dollars. The authors of the study recommend that the state allocate resources towards private well water treatment, as well as to “provide private well owners…legal recourse via nuisance lawsuits.”
A map of the contaminated wells accompanies the report. The location of the contaminated wells roughly map onto the locations of concentrated animal feeding operations in the state.
Water contamination has been big news in Iowa for years, as Des Moines Water Works has argued for better regulation of agricultural runoff into the state’s waterways. In response to its efforts, Republican legislators attempted to break up the agency.