DES MOINES, Iowa (KCCI-TV) – High nitrates levels are back in the Des Moines and Raccoon Rivers, prompting Central Iowa Water Works officials to turn-on their nitrate removal facility again. KCCI reports the facility turned on three of their eight nitrate removal vessels last week, which is a rarity for January. Plant officials, however, said all the water the facility produces is below the EPA safe drinking water standard of 10 milligrams of nitrates per liter that public water systems are required to meet that.

Former University of Iowa researcher Chris Jones tells KCCI the recent weather is worth considering as a reason for the rise in nitrate levels. According to Jones, the warm weather we’ve had kept the ground from freezing, and with no frost below four-feet, it remains thawed down where the field tiles, the agricultural field tiles are found.

When rain comes, it washes the nitrates out. Jones said the high numbers aren’t just hitting central Iowa. He noted the Cedar River on Thursday was almost 10 milligrams per liter.

In spring and summer 2025, the nitrate removal facility ran in part of fully for 112 days. A wet July drove nitrates out of farm field drainage tiles and into lakes and rivers. That all led to an unprecedented lawn watering ban in central Iowa last summer. The nitrate removal facility, located in Des Moines but operated by Central Iowa Water Works, has been in used since the 1990s. This is the fourth time in the facility that it has run in the winter.