A high level of nitrate in the Raccoon and Des Moines rivers is threatening drinking water in the Des Moines area.
Central Iowa Water Works (CIWW), a regional utility that supplies around 600,000 people, is prohibiting businesses and residents from watering their lawns so there is enough water available for necessities, such as drinking and bathing.
The root of the problem is that nitrate levels in the rivers that supply the water system are at their highest since 2013.
This is the first time the metro’s water system has put mandatory restrictions in place because of nitrates.
“We have ample source water, but the source water is so high in nitrate that it’s difficult for the plant to treat it at the same rate that customers are demanding it on the other side,” said CIWW Executive Director Tami Madsen.
The hope is conservation will allow treatment facilities to keep nitrate in drinking water below the legal limit of 10 parts per million. Madsen said levels going out of the plant are currently around 9 parts per million.
“Right now, your water is safe to drink,” Madsen said. “There are no concerns. Continue to drink your water. Just don’t put drinking water on your lawn. It doesn’t need drinking water.”
On Wednesday, CIWW had called for people to cut back on lawn watering by 50% voluntarily, but Madsen says there was no noticeable reduction in demand.
If nitrate in the drinking water provided by CIWW members rises above 10 parts per million, they would be in violation of the Environmental Protection Agency (EPA) standard, and pregnant women and children would be told not to drink it.
“If we end up in a space when we're well over that EPA threshold, we're really going to start worrying about our pregnant women and our children under the age of 6 months,” said Juliann Van Liew, director of the Polk County Health Department. “In those two populations, we have the ability to see poor birth outcomes, including potential birth defects. And we also have the possibility for those 0-6 month infants to end up with reduced oxygen in their bloodstream and to really end up in acute care.”
Van Liew cautioned against boiling water in an attempt to lower nitrate levels. It doesn’t help, she said. In fact it further concentrates the nitrate that is present.
CIWW has been running a nitrate removal system for more than 55 days, at a cost of $14,000 -$16,000 per day, in an attempt to keep levels down in the tap water that goes to customers.
This is the first time the metro’s water system has put mandatory restrictions in place because of nitrates. Madsen said the restrictions will go on as long as levels are high in the rivers.
Any other cutbacks are welcome, she said, such as putting off car washes, consolidating laundry to run fewer loads, taking kids to the city pool instead of running a sprinkler in the yard, or watering the garden by hand.
Madsen said enforcement of the watering ban is up to each of the member utilities in the region that are part of the CIWW, but could include fines or water shut-offs.
