The regional water authority that serves one in five Iowans issued a lawn watering ban in the Des Moines area on Monday.
Tami Madsen, executive director of Central Iowa Water Works (CIWW), said the system’s treatment plants are “struggling to keep up” with a spike in consumer demand and high nitrate concentrations in rivers and other sources that provide water.
“While we continue to meet all state and federal drinking water standards, we have reached a point where conservation is necessary to preserve treatment capacity and ensure reliable service for everyone,” Madsen said during a news conference.
Lawn watering consumes around 40% of the system’s drinking water supply in the summer, Madsen said.
“Lawn watering is the biggest single use that we can ask for a reduction of that can make the biggest impact the most quickly to make sure that we can continue to produce safe drinking water for our communities,” she said.
The CIWW Board of Trustees initiated Stage III of its Water Use Plan after asking customers for a 25% and 50% voluntary reduction in outdoor water use earlier in the spring.
The third stage is considered when customer demand exceeds 90% of the capacity of the treatment plants, said Amy Kahler, CEO of Des Moines Water Works, the largest contract operator for CIWW.
“We hit that threshold over the weekend,” Kahler said. “We estimate that customer demand will be at 98% of the treatment capacity [Tuesday] if we do not implement Stage III.”
Mandatory outdoor water restrictions
The following types of water use are restricted, effective immediately, throughout the CIWW service area:
- Lawn watering is prohibited except for newly installed sod or seed placed during the current growing season. Watering should be limited to the minimum amount necessary for establishment.
- Sports fields and golf courses may be irrigated only to the minimum necessary for safety and plant preservation.
- Decorative water features that do not recirculate water should be turned off.
- Customers should immediately discontinue all unnecessary outdoor water use.
Indoor conservation strongly encouraged
Customers are also urged to reduce indoor water use wherever possible by:
- Running dishwashers and washing machines only with full loads.
- Fixing leaking faucets, fixtures and running toilets.
- Turning off water while brushing teeth or shaving.
- Delaying non-essential, high-water-use activities.
How lawn watering bans help when nitrate levels are high
CIWW issued its first lawn watering ban last June and lifted it in July.
Iowa’s 2013 Nutrient Reduction Strategy and the Central Iowa Source Water Research Assessment released last year identify agriculture as the primary source of nitrate and other nutrients in Iowa’s water.
The U.S. Environmental Protection Agency sets legal nitrate limits in public drinking water at 10 milligrams per liter.
CIWW draws from multiple water sources across its service area, leaning more on some sources when nitrate levels are high in others.
Kahler described the infiltration gallery, a series of underground pipes throughout Water Works Park next to the Raccoon River, as “our very best water source.” Over the weekend, nitrate levels in the infiltration gallery reached 12.3 milligrams per liter.
“That is higher than all of last year,” Kahler said. “The gallery is setting new records, and it's been over 10 milligrams per liter for almost 90 days, which is the highest number of days on record.”
Kahler said CIWW has relied heavily on water from the Dale Maffitt Reservoir this year, drawing out about 3.5 million gallons a day.
“We have used about 50% of the capacity … that is available to us thus far in 2026,” Kahler said. “We had to use that throughout the winter. That's not something that we do. We like to save that water for emergencies.”
Two of the CIWW water treatment plants have capacity to remove nitrates. The Saylorville Water Treatment Plant uses reverse osmosis, while the Fleur Drive Treatment Plant uses an ion exchange process.
Operating the nitrate removal facility at Fleur Drive can cost $16,000 per day when operating at full capacity.
“We do budget for that based on historical trends. For the last couple of years, we have not budgeted enough, and so, we have exceeded that budget,” Kahler said.
As of Monday, Kahler said the Fleur Drive nitrate removal facility had run for 148 days in 2026, representing about 95% of the year so far. The record was set in 2015 with 177 days.
“As water utilities, we can’t control the nitrate levels in our sources,” Kahler said. “But again, the one thing we can manage right now, in the moment, is demand.”
Amid public outcry surrounding data centers and water usage, West Des Moines Water Works said the six Microsoft data centers in its jurisdiction used 2.4% of total water usage in West Des Moines in 2025.
Enforcement actions during the lawn watering ban are determined by each member agency, Madsen said.
Kahler said Des Moines Water Works will hang a tag at the property and try multiple ways to contact a customer if a report comes in.
“If the lawn watering has still gone on for two days beyond that, then we will terminate water service or turn the water off to the home,” Kahler said.
She added that customers who want to report possible irrigation infringements can contact report@dmww.com.
