KCCI Investigates: Central Iowa Water Works' nitrate removal facility runs for 107 days in 2026

The nitrate removal facility of Central Iowa Water Work partially has been running for 107 days so far this year.The facility goes on when levels of the contaminant nitrate go high in the Des Moines and Raccoon rivers, the two main sources for drinking water in central Iowa. In recent years, the levels have trended upward, says David Cwiertny, a professor at the University of Iowa. “It’s this time of year, we know that our highest nitrate levels usually come later in the year. We’re thinking like May, June,” Cwiertny said. “To see them this high now, I know, is probably causing a little bit of worry amongst water providers that we’re having to sort of play the games that we played to provide safe water.”The nitrate removal facility uses a powder-like resin to help bind to the nitrates to remove them from the water. It ran Jan. 6 through March 2. Operating resumed March 9 and continues through today. The Environmental Protection Agency guideline allows 10 milligrams per liter of nitrate in all treated drinking water.Central Iowa Water Works continues to meet that standard despite the higher pollutant levels seen at most times this year.CIWW conducts testing to monitor the levels. Data this year show the Raccoon River has had levels of 10 mg/l 100 days this year, while the Des Moines River has logged 88 days above that mark. Treated drinking water from CIWW is at about 8 mg/liter. On Feb. 4, the reading was at 9 mg/liter.”I think the concern that many Iowans have is that’s pretty high, and some science has suggested those levels can still be problematic,” Cwiertny said. The EPA set the standard in 1991. It has not set a timeline for revisiting the topic.”I think it is important to understand that treatment really is just lowering the levels, just usually just below where they feel confident that they can make sure they’re under the standard,” Cwiertny said.