The Des Moines Water Works board on Thursday is expected to consider taking legal action against an undisclosed number of upstream livestock and crop farms that contributed to record nitrate runoff.

Nitrates, which occur naturally but also come from fertilizers and sewage, have been associated with a condition that suffocates infants and with a variety of cancers.

Waterworks General Manager and CEO William Stowe said the state’s voluntary program to cut farm runoff is a failure marked by record nitrate levels in local rivers in summer and now, unusually, in winter. The utility, which serves 500,000 customers, turned on  its $7,000-per-day nitrate-removal system Dec. 4, and may eventually have to spend tens of millions of dollars to update the 20-year-old system, Stowe said.

The utility decided to consider more direct action. If the board approves, waterworks would give the required 60-day intent to sue notice to polluters it has been watching daily for about a year. The action would be under the federal Clean Water Act.

“Realistically, we have for most of the past year been looking at a number of  polluters in northern Iowa that will be the focus of our discussion,” Stowe said. “The evidence is clear that these parties are groundwater polluters.” 

If the board approves action at its 3:30 p.m. meeting Thursday, the utility will release data showing how the livestock and crop farms contributed to the problem, he added.

Stowe said nitrates on the Raccoon River system have been as high as 19 milligrams per liter recently, nearly double the health limit.

The board meets at Des Moines Water Works headquarters, 2201 George Flagg Parkway.