Levels of nitrate observed in roughly 1,100 groundwater systems and more than 13,000 private wells are still low enough to meet federal guidelines. But because drinking tap water with even small amounts of nitrate in it may be a risk factor for cancer and birth defects, the Environmental Working Group called in its report for an “aggressive policy and programmatic approach” to address the situation in Minnesota.
Under the federal Clean Water Act, drinking water that contains less than 10 milligrams of nitrate per liter is considered to be safe for human consumption. In past research, however, the Environmental Work Group found thresholds of half that amount and less may increase the risk of illness.
“It is clear that protecting public health requires keeping the contamination level far below the legal limit,” the report reads.
Nitrate, a compound found in fertilizer and manure, can be washed away from crop fields and seep into groundwater sources by rain and irrigation. Many of the contaminated water sources identified in the Working Group’s report are located in rural Minnesota.
Based of state and federal data, the Working Group estimates that