In the early spring of 2014, two lab workers for the Des Moines Water Works climbed into a truck and drove north. They pulled over on Highway 20 where the road crosses Cedar Creek, made their way to the water’s edge, dunked a cup attached to a pole, then poured the contents into a container. It was the first of 40 outings over the next nine months to collect samples from creeks, ditches, and drainage outlets—72 locations in all—amid the corn and soybean fields north of Des Moines.
An analysis of the samples confirmed what the utility’s employees had long suspected: Nitrate from farm fields was flowing into the Raccoon River, one of the primary sources of drinking water for Des Moines. A form of nitrogen, nitrate is a source of nourishment for plants. Farmers apply it to crops through fertilizer or animal manure. Too much nitrate in drinking water can cause health problems, including a potentially fatal blood disorder in infants called blue-baby syndrome.