CIWW Resumes Commercial Irrigation, Continuing the
Phased Exit from the Stage III Watering Ban

DES MOINES, Iowa (July 29, 2025) — Central Iowa Water Works (CIWW) announced today that

commercial irrigation and lawn watering can resume on Wednesday, July 30, as part of the

phased exit from the Stage III lawn watering ban initiated on June 12.

The CIWW Technical Committee met today and voted to allow commercial watering based on

nitrate concentration in the authority’s water sources and low customer demand as a result of

frequent rain showers.

The committee’s vote reflects the confidence that CIWW can continue to meet all safe drinking

water standards while meeting the anticipated increase in water demand from commercial

irrigation. The U.S. Environmental Protection Agency standard for nitrate concentrations in

treated water is 10 milligrams per liter (mg/L). CIWW has met the standard throughout this water quality event by managing water demand and nitrate removal capacity.

“In making this decision, the Technical Committee analyzed and studied the most recent nitrate trends, production capacity throughout the system and current water demand, which includes residential lawn watering,” explained Tami Madsen, executive director of CIWW. “The water quality challenge we have been facing this summer is stabilizing. We thank water customers region-wide for complying with the lawn-watering ban and for continuing to follow the even-odd watering schedule and other conservation guidance once restrictions were lifted. These efforts support moving to the next phase.”

Commercial customers are asked to follow the region’s

lawn watering schedule:

• Even numbered addresses - Sunday, Wednesday or Friday

• Odd numbered addresses - Tuesday, Thursday or Saturday

• No watering on Monday

CIWW’s Fleur Drive Treatment Plant relies on source water from the Raccoon and Des Moines

rivers as well as the infiltration gallery, a 3-mile stretch of underground pipes.

While seasonal spring-summer spikes of nitrate levels are common, this year stands out

because all three primary water sources simultaneously experienced 33 days of historically

high concentrations higher than 10 mg/L from June 8 –16.

Today’s levels were 13.63 mg/L in the Raccoon River, 10.71 mg/L in the Des Moines River and

8.67 mg/L in the infiltration gallery. The finished drinking water from the Fleur Drive plant is

7.33 mg/L.

The nitrate removal facility at the Fleur Drive plant continues to operate and has been in

operation for 102 days through today.

The phased exit from the Stage III ban will be complete once lawn watering resumes for local

governments and schools.

About Central Iowa Water Works

CIWW is a collaborative regional utility responsible for water system planning, drinking water

treatment, and wholesale delivery of drinking water to approximately 600,000 people in Central

Iowa.

The 12 founding members of CIWW are Ankeny, Clive, Des Moines Water Works, Grimes,

Johnston, Norwalk, Polk City, Urbandale Water Utility, Warren Water District, Waukee, West

Des Moines Water Works and Xenia Rural Water District. Des Moines Water Works also

includes Alleman, Berwick, Bondurant, Cumming, Pleasant Hill, Runnells, Unincorporated

Polk County and Windsor Heights.