Key Iowa Swing Districts in U.S. House Could Hinge on Water Quality and Cancer Concerns

Control of the U.S. House of Representatives this year could be determined by Iowa candidates’ positions on clean water protections, a new report from Food & Water Action finds. The statewide poll, conducted by Global Strategy Group and released February 17, found that 82% of Iowa voters polled would be more likely to support an elected official who makes protecting clean water a top priority, including by cutting industrial agriculture pollution.

The report comes as Iowa faces rising rates of nitrate pollution linked to industrial agriculture and rising cancer rates. According to poll results, voter concern over water quality now exceeds traditional campaign issues including cost of living, crime and public safety in Iowa’s first and third congressional districts, two of the most competitive U.S. House seat races.

Iowa has some of the most polluted waterways in the United States. Over half of Iowa’s rivers and streams are designated as impaired, meaning that they do not meet quality standards for their intended use — such as drinking, fishing or recreation — by the Iowa Department of Natural Resources. The Des Moines metro area water system operates an enormous nitrate removal system, the largest in the world when it was built. In 2025, the system ran for 112 days, costing upwards of $10,000 per day and triggering a lawn-watering ban to ensure that the metro area had enough safe drinking water.

Exposure to nitrate pollution is linked to increased risk of cancer and thyroid disease in adults and life-threatening illnesses for children, including methemoglobinemia, or blue baby syndrome. Today, Iowa has the second-highest new cancer rate in the United States and is one of only two states where cancer rates are rising.

Iowa’s first and third congressional districts are two of the 18 Republican-held House seats that Cooke Political Report rated as a toss-up in this year’s midterm elections. In order to gain control of the House, Democrats would have to win three additional seats.

Incumbent U.S. Rep. Mariannette Miller-Meeks (R-Iowa-01) held her seat by just 800 votes in 2024, one of the tightest races in the country. This year, Miller-Meeks runs against Democrat Christina Bohannan, who outpaced Kamala Harris in 2024.

Meanwhile, incumbent U.S. Rep. Zach Nunn (R-Iowa-03) had considered running for governor last year but opted instead to seek reelection after a meeting with President Trump, citing a commitment to maintaining the Republican House majority.

Neither Miller-Meeks nor Nunn “have so much as acknowledged that Iowa’s water and cancer crises even exist,” according to Sam Bernhardt, political director at Food & Water Action.

The poll surveyed a group of 600 registered voters in Iowa that was demographically and geographically representative of the state population as a whole. Across party lines, the majority of respondents prioritized cutting pollution from industrial agriculture. Seventy two percent of Republicans, 86% of independents and 92% of Democrats polled would be more likely to vote for an elected official who makes protecting clean water — including reducing pollution from industrial agriculture — a top priority.

An even larger majority of respondents (79%) favor restoring funding for the statewide Iowa Water Quality Information System and 79% support mandatory pollution reduction requirements. The Iowa Legislature slashed funding for the statewide water quality monitoring system in a 2023 bill, and the Cedar Rapids Gazette reports that the program’s current funding will run out in July.

“A lot of Iowa politicians are scared to talk about water quality. They’re worried it’ll upset powerful groups like Farm Bureau, who bankroll their campaigns,” said Rep. Austin Baeth (D-Iowa-36) in a video on TikTok about the poll results. “But as Iowa’s cancer rate rises and our polluted water comes under suspicion, Iowans are begging us to do something.”

Nitrate pollution in Iowa’s water is strongly tied to agricultural pollution. Sources of water pollution are difficult to track, in part because Iowa law classifies records of where and how much manure is spread as “confidential.” State funding for the Department of Natural Resources was also cut in half between 2009 and 2018, reducing its capacity to enforce water regulations.

But what we do know, as Iowa Water Quality Bureau Chief Lori McDaniel said in 2024, is that around 90% of Iowa’s water pollution originates from non-point sources, or those that stem from diffuse, scattered and diverse sources, which includes agriculture. And Polk County’s Central Iowa Source Water Research Assessment attributed 80% of all nitrates in the Des Moines and Raccoon rivers — heavily-used waterways that merge in Iowa’s capital — to agricultural fertilizers.

The issue follows decades of agricultural consolidation across the United States: Between 2017 and 2022, farmland nationwide decreased by 2% while the average farm size increased by 5%. Farmers have reduced the amount of labor and land used to farm by increasing inputs such as machinery, farm structures, pesticides and fertilizer.

This is particularly acute in Iowa, where more than one-third of the nation’s hogs — approximately 23 million of them — are raised. The vast majority of hogs are kept in large factory farms, also known as confinement farms, which produce an estimated 110 billion pounds of manure each year. All that manure must go somewhere, and usually it is spread over farm fields as fertilizer. Nitrogen from both synthetic and manure-based fertilizers entering Iowa waterways rose nearly 50% over a two-decade period, a 2018 study found. However, the Iowa Department of Natural Resources doesn’t collect records of where and how much manure is spread on Iowa’s fields.

“The impacts of intense consolidation and industry growth show in the degraded quality of Iowa’s waterways, the loss of economic vitality in its rural communities,” Jennifer Breon, senior Iowa organizer at Food & Water Action, said at a press briefing last week. “One of our most traditional farm states demonstrates in a very real way that our current food system is not actually working for a vast majority of people.”

Those personally impacted by water pollution in the past five years represent 43% of poll respondents, and 94% of them rated water quality and pollution issues as serious. Of those who have not been impacted by water quality issues, 78% still found the issue to be serious, suggesting that political pressure could rise as Iowa approaches the midterm elections during its heavy rainfall season, when agricultural runoff is typically at its worst.

“Iowa’s water and cancer crises are widely and deeply felt. Few families have not been impacted,” said Breon. “I am tired of diagnosing my patients with cancer,” said Baeth, who is a physician. “Iowans deserve better.”