Hear from CIWW as mandatory lawn watering ban issued in Des Moines metro
Hear from CIWW and Des Moines Water Works as Des Moines metro is placed under a lawn watering ban for the second consecutive year on June 8, 2026.
Central Iowa residents face a second consecutive summer banned from watering their lawns as Central Iowa Water Works seeks to preserve its capacity to produce sufficient safe drinking water.
CIWW announced the ban Monday, June 8, after Des Moines Water Works, its largest utility, estimated that with temperatures set to surpass 90 degrees Tuesday and high nitrate levels requiring it to provide additional treatment, demand would reach 98% of capacity.
Already, the system’s nitrate removal facility, among the world’s largest, was operating “at full throttle,” Des Moines Water Works CEO Amy Kahler said during a Monday news conference.
Here’s what to know about the ban.
Why is Central Iowa Water Works requiring a ban?
CIWW officials warned in early May that a lawn-watering ban like the one imposed in June 2025 was likely after a winter during which high nitrate levels in central Iowa’s source water — the Raccoon and Des Moines rivers — failed to abate.
Elevated nitrate concentrations in the rivers require “significantly more treatment” to achieve a federal safety standard of no more than 10 milligrams per liter, Tami Madsen, CIWW’s executive director, said at Monday’s news conference. Lawn watering greatly increases demand in warm weather, and “we have reached a point where conservation is necessary to preserve treatment capacity and ensure reliable service to everyone,” Madsen said.
Who does the ban affect?
Customers of Des Moines Water Works are the largest group. Also under the ban are Ankeny, Clive, Johnston, Norwalk, Polk City and Waukee and areas served by Urbandale Water Utility, West Des Moines Water Works, Warren Water and portions of the Xenia Water District.
Grimes, a member of the CIWW, isn’t under the ban because it’s not yet connected to the shared water distribution system.
How high have nitrate levels been?
In addition to the Raccoon and Des Moines rivers, the nitrate levels in the Des Moines Water Works’ infiltration gallery, a system of water naturally filtered through rock and sand, have been unusually high, Kahler said.
The gallery typically is the utility’s best water source. But it has been over the 10-milligrams-per-liter limit for nearly 90 days, which Kahler called a record.
On Tuesday, nitrate levels were 14.98 milligrams per liter in the Raccoon River; 11.75 milligrams in the Des Moines River; and 11.83 milligrams in the infiltration gallery, Des Moines Water Works reported.
Nitrates, even at low levels, have been tied to some cancers and to serious illness in infants. The federal government requires water utilities to alert consumers when nitrate levels rise above the standard.
What’s causing high nitrate levels in the Raccoon, Des Moines rivers?
Farming contributes about 80% of the nitrates in the Raccoon and Des Moines rivers, according to a Polk County water analysis released last year.
Iowa farmers use commercial nitrogen as well as manure from millions of pigs, chickens, turkeys and other livestock to fertilize the state’s roughly 24 million acres of corn and soybeans. Nitrogen and phosphorus, two nutrients that can befoul Iowa waterways, also naturally occur in Iowa’s rich soil.
Weather plays a major role. Drought, for example, can result in a buildup of nutrients in the soil. When rains return, as they have the past two springs, they can pick up the contaminants and move them to waterways both over land and through the drainage tiles that underlie about 13 million acres of farm fields across Iowa.
What’s being done to cut fertilizer losses?
The state adopted the Iowa Nutrient Reduction Strategy in 2013, setting a goal to cut by 45% the nitrogen and phosphorus that reach Iowa streams and ultimately flow into the Mississippi River, contributing to the dead zone around the river’s mouth in the Gulf of Mexico, renamed the Gulf of America by the U.S. government.
The state and federal governments offer farmers financial and technical assistance to adopt practices like planting cover crops and reducing or eliminating tillage to cut fertilizer losses. They also encourage establishing buffer strips, bioreactors and wetlands that help clean water as it leaves fields.
More: With billions invested in farm conservation, is Iowa’s water cleaner?
In May, Gov. Kim Reynolds announced the state will give CIWW a $25 million grant to expand and upgrade its nitrate removal facilities, part of a statewide overhaul of Iowa’s water quality funding. However, the state so far has declined to impose measures to reduce nitrates from agricultural runoff, with Reynolds saying in July 2025 that regulation “is hardly ever the answer.”
Are candidates addressing the issue?
Zach Lahn, the GOP nominee to replace retiring Republican Reynolds in this fall’s gubernatorial election, has said Iowa must “start addressing the problem at the source — not just relying on expensive treatment upgrades after the damage is already done.”
“Upgrading water treatment facilities may help in the short term, but it’s ultimately a Band-Aid approach that passes massive costs onto taxpayers and communities,” Lahn said in a post on Facebook.
Democratic nominee Rob Sand points to improved water quality as part of an effort to address Iowa’s growing cancer rate, and calls for a variety of initiatives including tax breaks for farmers who adopt conservation measures, improved water monitoring and more transparent tracking of farmers’ manure use.
“These proposals aren’t a promise to solve Iowa’s water quality issues and cancer crisis overnight,” Sand says on his campaign website. “There aren’t any realistic ways to do that overnight. But they are a promise to move our state in the right direction and the first steps towards seeing improved water quality and cancer rates in the coming years ― not the coming centuries.”
Iowa Agriculture Secretary Mike Naig, a Republican seeking reelection, has maintained that growers are making progress in preventing fertilizer losses, including leading the nation in adopting cover crops and other conservation practices and building infrastructure like wetlands.
But, he added on June 3 at the World Pork Expo in Des Moines, “There is no finish line when it comes to soil conservation and improving water quality. We can always do more.”
Chris Jones, an Iowa City Democrat and longtime activist on water quality who is challenging Naig for the agriculture secretary post, said in a statement Tuesday that the state’s approach to cutting agricultural runoff is not working.
“Des Moines area residents and people all across Iowa now commonly spend hundreds or thousands of dollars for in-home water treatment for peace of mind as they worry about their and their loved ones’ health,” Jones said, pointing to news that Iowa is one of only three states with rising new cancer rates, according to this year’s Cancer in Iowa report.
Is data center water use contributing to the water crisis?
Concern has been rising about water consumption by proliferating data centers, which use it to cool their equipment. Tech giant Microsoft, with a growing array of data centers in West Des Moines, used about 2.4% of the city’s total water last year, West Des Moines Water Works reported. It was 0.3% of the CIWW network’s overall water use in 2025.
Christina Murphy, general manager of West Des Moines Water Works, said Microsoft was nevertheless the city’s largest user in 2025, consuming 62.3 million gallons, primarily because other large business users were prevented from watering their lawns during last year’s ban. She said Microsoft does not irrigate its lawns.
Microsoft agreed in 2023 to provide West Des Moines Water Works with $25 million to provide large surface and underground water storage facilities that will offset its water usage, Murphy said.
The 300 million gallons of underground storage is still being developed, she said, adding that Microsoft also is moving to systems that reduce its water usage.
The lawn-watering ban isn’t about how much water CIWW can produce, but its capacity to treat high nitrate levels in its source water, Murphy said. “We have lots of capacity to treat water, just not with these levels of nitrates,” she said.
What about my new sod, garden and flowers?
The ban does not prevent residents from watering newly installed sod, seeded areas and trees or hand watering gardens and flowers, officials said. It also does not prevent watering of golf courses and sports fields.
CIWW encourages residents, in addition to refraining from lawn watering, to conserve home water use, including running dishwashers and washing machines only with full loads and fixing leaky faucets and toilets.
How long will the ban last?
The ban will continue until nitrate levels drop enough to guarantee there is sufficient treatment capacity to allow lawn watering to resume. For reference, last year’s ban began June 12. It began easing in stages on July 18. The last restriction ended Aug. 15.
Is central Iowa’s water safe?
“I want to be clear about one thing: Our drinking water is safe,” Madsen said at Monday’s news conference.
Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com.
