Iowa voters are increasingly raising public health concerns over the state's water quality as the governor's race heats up ahead of November.
The latest annual report from the Iowa Cancer Registry shows the state has the second-highest rate of cancer in the country and is one of only a few states where cancer rates are on the rise.
Now, the conversation about how water quality in this state, dominated by the agriculture industry, may contribute to the high cancer rates, and how to respond, is moving from the farm fields to the governor's race.
Both candidates for governor, the Democratic nominee Rob Sand and the Republican nominee Zach Lahn, say more needs to be done.
A nonpartisan push for clean water
On an overcast summer day, farmer Zack Smith crouches between rows of soybeans to demonstrate why he and two other farmers in the region who call themselves the Lobe Rangers are choosing to leave the brown stalks of last year's crops right next to rows of vibrant green soybeans.
"The residue that's left over is essentially acting as kind of an armor on the soil," Smith said. "It equates to when it rains here, more likelihood for the water to go into the soil versus running off."
This practice, called strip tilling, might not be as aesthetically pleasing as other conventional methods that pull out the roots of dead plants.
But for Smith, the roots of last year's crops are helping lock nitrogen fertilizer into the soil, lowering the risk of it running off and contaminating nearby sources of drinking water. That's important because nitrate in the soil can travel through underground farm drainage tiles into streams and rivers that eventually turn into drinking water.
Many Iowans also get their water from private wells where water does not have to meet the federal standard.
Smith, along with Matthew Bormann and James Hepp, created the Lobe Rangers, a nod to the Des Moines Lobe region where they farm, to advocate for improvements to the state's water quality and influence public opinion and policy in farm country.
They say they've watched as state lawmakers have implemented voluntary measures to improve water quality, and while they are from different political backgrounds, they all agree that conservation practices like strip tilling and planting cover crops need to be more widespread.
Concerns over clean drinking water have become central to both gubernatorial candidates' campaign messages.
"I think the Democratic Party at its best is the party for the little guy," Sand told a crowd in Corydon, Iowa, recently. "I'm also a believer that we want to have clean water to fish in and abundant public land to hunt on, and the Democratic Party is more of a supporter of those things."
While Democrats have traditionally raised concerns over environmental pollution, this year, Sand's GOP opponent is trying to upend that convention.
"It's gotten to the point where you just can't ignore it anymore, you can't, and I've been trying to talk to Republicans about this every chance I get," Lahn said in an interview with NPR.
So far, both candidates have largely focused on voluntary or incentivized measures to improve water quality.
But the Lobe Rangers say voluntary conservation isn't enough.
Bormann, a fifth-generation farmer, has been farming in Iowa for more than 25 years and previously served as president of the Kossuth County Farm Bureau.
Yet, he says, it's often farmers with the state's agricultural groups who "aren't ready" for change. Bormann points to trade associations like the Iowa Farm Bureau and the Iowa Corn Growers Association. "They think if they can just avoid it, you know, and steer the group, the ag group, you know, steer them to avoid it, or to greenwash the message, then it's going to go away, but this isn't going away anymore," Bormann said.
NPR reached out to the Iowa Farm Bureau and the Iowa Corn Growers Association for comment but did not hear back.
The Iowa Farm Bureau and Corn Growers, along with other industry groups, submitted an op-ed to several Iowa newspapers last year, writing that nitrate levels "naturally fluctuate seasonally, especially during heavy rainfall, but have remained relatively stable."
A report from the Iowa Department of Natural Resources showed Iowa had 36 nitrate-related drinking water violations in 2025, which is more than double the number reported in 2024.
Voluntary programs fail to significantly reduce pollution
More than a decade ago, the state acknowledged the need for new conservation efforts by creating the Iowa Nutrient Reduction Strategy, a voluntary plan aimed at reducing nitrogen and phosphorus runoff on farms.
But adoption has lagged behind the level researchers say is needed to significantly reduce nitrate pollution.
In 2023, Iowa Public Radio spoke to experts about the effectiveness of the program and found that while nitrogen levels were up and down during that time, there was no significant change.
David Cwiertny, who directs the University of Iowa's Center for Health Effects of Environmental Contamination, says studies have found links between elevated nitrate levels in drinking water and long-term health risks that are not reflected in current federal drinking water standards.
"What's most bothersome to me is that when you know the EPA acknowledges the science is there and it needs to be studied to determine if the standard is sufficiently protected to public health," Cwiertny said. "Then that doesn't get done, it leaves you know, water providers in Iowa in a tough spot. It leaves consumers in Iowa in a very difficult position."
Nitrate spikes this summer lead to lawn watering restrictions
Des Moines Water Works, a public water utility, has a long history of treating nitrates in its water supply in the Des Moines and Raccoon Rivers.
The U.S. Environmental Protection Agency sets legal nitrate limits in public drinking water at 10 milligrams per liter.
For the past two summers, nitrate readings in the rivers have spiked above that limit, reaching some of their highest levels in over a decade.
That led to lawn watering bans in the Des Moines metro area so that drinking water treatment facilities could keep up with removing nitrates.
All water use restrictions were lifted earlier this week. The regional drinking water authority, Central Iowa Water Works, says nitrate concentrations in its main sources dropped below the EPA's limit.
While the situation has improved, CIWW says it plans to expand its nitrate removal facility.
Water spills over into the governor's race
Water quality frequently surfaces at campaign events, including town halls held by Democratic candidate and State Auditor Rob Sand.
Sand has made improving water quality part of his campaign while positioning himself as a moderate capable of attracting Republican voters in a state that has marched to the right over the last decade.
"Nitrates do, at a certain point, cause cancer," Sand told NPR before a town hall last month in Corydon, Iowa.
"What that level is, is something that is an item for discussion, but at the same time, we also see nitrate levels in Iowa that are above even the high level of where people think that link is for safe consumption," Sand said.
Sand has proposed tax incentives to encourage landowners to convert more acreage into wetlands, which naturally filter water before it reaches rivers and streams.
He and his Republican opponent have also called for funding a statewide water quality program that voters approved 16 years ago that has never received funding.
Zach Lahn made Iowa's water quality and rising cancer rates central themes of his campaign after winning a crowded GOP primary in June. He narrowly defeated Congressman Randy Feenstra, who had the backing of President Trump. Trump has since endorsed Lahn.
Lahn was also endorsed by the MAHA-PAC, a super PAC aligned with Health Secretary Robert F. Kennedy Jr.'s "Make America Healthy Again" movement.
"It doesn't matter how low your taxes are. If your kids are leaving, your people are dying, you're not winning," Lahn said.
Back on the farm in north central Iowa, the Lobe Rangers say the growing attention to water quality is encouraging.
"So the fact that we're talking about it denotes that there's a problem, and we just got to get more people on board to do something about it," Bormann said.
The farmers have built an online following by posting videos about agriculture's role in protecting water quality, and while they're not endorsing candidates, they've agreed to meet with both Sand and Lahn.
Iowa Public Radio's Rachel Cramer contributed to this report.
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