IOWA -- Iowa's problem with high nitrate levels in lakes and rivers is getting worse.
Iowa has 61 nitrate sensors in use on rivers across the state.
According to the Cedar Rapids Gazette, 40% showed an average daily concentration of nitrates in 2016 above the federal standard of 10 milligrams per liter. This included the Raccoon River, which is the source of drinking water for the Des Moines Water Works.
The average daily concentration for the Raccoon River was 11.5 milligrams per liter.