Wisconsin is among 10 states that have seen growing problems with nitrate contamination in drinking water, according to a new report by Environmental Working Group (EWG).

Nitrate contamination stems from a variety of sources, including farm runoff and leaking septic tanks or sewage. Long-term exposure to excess nitrate levels can cause blue-baby syndrome — a condition that affects how oxygen is transported through the blood. Nitrate exposure in infants under six months can cause serious illness or death...