Of Corn and Cancer: Iowa’s Deadly Water Crisis

But in 2025, several events changed the situation. The first is that on May 30, Central Iowa Water Works, a utility conglomerate responsible for providing drinking water to 600,000 people in the state’s largest metropolitan area, Des Moines, and surrounding cities, asked residents to reduce lawn watering by 25 percent. The reason was not extreme heat or drought. Quite the contrary. After a few years of drought, central Iowa experienced an extremely wet spring, and all that rain triggered a massive transfer of nitrates and other chemicals from agricultural soils into waterways. The utility’s two main water sources, the Des Moines and Raccoon rivers, were so full of nitrates that Des Moines’ nitrate removal machine, among the largest in the world, couldn’t keep up. In less than two weeks, demand for a reduction rose to 50 percent. And on June 12, Central Iowa Water Works banned lawn watering altogether. “CIWW made the decision to enact the first-ever lawn watering ban to ensure that treatment facilities can produce enough water for essential needs amid water supply problems caused by high nitrate concentrations in raw water,” the agency said. Operating at full capacity, Des Moines’ denitrification system can cost about $16,000 per day.

During the summer of 2025, heavy nitrate pollution exceeded the system’s ability to provide a full supply of water meeting EPA standards. As of mid-June, the Des Moines and Raccoon rivers both had nitrate levels near 15 parts per million, Central Iowa Water Works reported in daily updates to its users. Levels fluctuated until the end of July, mostly above limits. On July 30, when levels in both rivers were just below the threshold of 10 parts per million, the agency ended the watering ban and allowed residents to water every other day.

Even though Central Iowa Water Works has carefully avoided naming Iowa’s agricultural industry in its daily web updates, all the brutal news about high nitrate levels in source water sets the stage for another shake-up. On July 1, at the height of the furor over the water ban, a water quality report commissioned two years earlier by Polk County, home to Des Moines, was released. This was not your typical, boring “report on county problems” story. He dominated media front pages and radio reports because he broke Iowa’s veil of comfortable silence about the state’s dire water situation to speak out. Its authors were a team of 16 scientists from across Iowa and the country, including Larry Weber, Chris Jones’ former supervisor at the University of Iowa Hydraulic Research Institute and co-author of several water quality papers.