Central Iowa Water Works (CIWW) banned lawn watering June 12 to keep drinking water from exceeding the Environmental Protection Agency’s (EPA) standard for nitrate. It’s the first time CIWW has ever implemented this kind of ban.
The action is part of the Stage 3 Water Shortage Plan. As the watering ban continues, customers who violate the policy may have their service turned off and possibly face fines.
In this case, the problem isn’t about the amount of water coming in; the problem is about the nitrate levels in the Des Moines and Raccoon rivers. The nitrate levels are the highest they’ve been since 2013.
The EPA limit for nitrate levels is 10 mg/L. On June 16, the Des Moines River was at 15.6 mg/L and the Raccoon River is at 15.3 mg/L.
Why are nitrate levels so high right now?
Des Moines Water Works CEO and General Manager Ted Corrigan said that crop fields are the primary source of nitrates in the rivers.
“We're going to need your continued support. This … is likely going to be measured in weeks, not days,” he said.
Rain is another factor in an already dynamic situation. If it rains in the Des Moines metro area, that might provide some relief, Corrigan said. But if it rains in the watersheds, runoff from the landscape may end up increasing nitrate levels.
“Sometimes our nitrate removal facility doesn't run for months, or even years, at a time because nitrate concentrations in our source waters are low,” Corrigan said. “We don't need to use those facilities to meet the standards, but right now, we are facing a very significant nitrate challenge.”
Christina Murphy, the general manager at West Des Moines Water Works, said central Iowans have complied with the mandatory ban. Demand for water has decreased by 30%. However, water treatment plants are still working at maximum capacity.
CIWW is implementing a long-term plan to add treatment capacity. Over the next seven years, staff will add the capacity to treat 34.2 million gallons a day — a 25% increase. Using membrane technology, the plants will not only filter out nitrates, but other potential contaminants, as well.
The projects are estimated to cost $344 million in addition to the cost of delivering the water, according to Murphy.
How can high levels of nitrate be harmful in drinking water?
Water that exceeds 10 mg/L of nitrate can cause blue baby syndrome in infants under 6 months. A baby’s skin turns blue because nitrates take away oxygen in the blood. The water cannot be boiled because boiling intensifies the nitrate concentration.
Pregnant women should not drink water that exceeds the maximum contaminant level.
Contact your health care provider or county health department if you have any concerns.
