Until the drought, water engineers at the Des Moines Water Works had to make a difficult choice every morning between two rivers that supply the 600,000 people in Iowa’s capital city with clean drinking water. Would it be the Raccoon River, flowing from the northwest and often laced with levels of nitrates in excess of federal safety standards, or the Des Moines River, flowing from the north and often carrying dangerous concentrations of cyano-bacteria in burgeoning populations of algae? It’s a no-win choice: Extended exposure to nitrates in drinking water has been linked to a range of cancers, the consumption of algae to kidney and liver damage and an array of acute symptoms.
But there’s been a twist to this unappealing choice, some version of which is playing out in cities across the Midwest that lie astride major rivers. For much of the fall, the drought in Iowa made the decision easy for Ted Corrigan, a water engineer and CEO of the Des Moines Water Works. Less rain meant less nitrogen seeping from the fertilizer applied across the state’s millions of acres of farmland and running off the tiles that undergird many fields into the Raccoon.