Factory Farms and Foul Waters

A NextGen Blog post by Marianne Swan, SUNY Oneonta.

Photos © Alison M. Jones.

This is the latest post to our NWNL NEXTGEN BLOG series. Since 2007, NWNL has supported watershed education with college internships and blogging opportunities. This NWNL NEXTGEN BLOG series posts students’ essays; sponsors a forum for our student contributors; and invites upper-level students to propose work focused on watershed values, threats and solutions.

A recent graduate of SUNY Oneonta, Marianne Swan is pursuing a career in the field of environmental sustainability with particular interest in food and water security. Read her earlier NWNL posts, New York’s Onondaga LakeWildfires & Water Water and the 2020 Election, Environmental Personhood and A New Wave of Water Protections.

Most of America’s animal products come from massive factory farms, known as concentrated animal feeding organizations (CAFOs). As defined by the United States Department of Agriculture, a CAFO is an intensive animal feeding operation in which over 1,000 animal units (particularly pigs, cows and chickens) are confined for over 45 days a year. Untreated animal waste from CAFOs have become a huge threat to water quality. Furthermore, CAFOs are overwhelmingly located in poor rural areas where residents don’t have the resources to fight their presence. In defense of CAFOs, agricultural states cite the importance of their local economic contributions and jobs. But the explosion of CAFOs has environmental groups, residents and legislators pushing for a ban on new factory farms.

Iowa farm for cattle

Iowa itself is home to 25 million hogs and pigs, a third of the national total.[mfn]Thessen, Greg[/mfn] Thus in the last decade, Iowa led the way for CAFO expansion. In 2019, the state’s pork industry provided nearly 150,000 jobs and $6.8 billion in household income.[mfn]Eller, Donnelle[/mfn] While this revenue is significant, so are the environmental costs of CAFOs.

Less than 20 percent of Iowa’s rivers and streams meet water quality standards; two-thirds of the state’s lakes and reservoirs are impaired.[mfn]Iowa Department of Natural Resources[/mfn] To preserve ecosystem integrity and a clean water supply for the public, Iowa must make water quality a priority. It will be impossible to do this without addressing the impact of CAFOs.

Little Maquoketa River, Iowa


The animals in Iowa’s factory farms produce 70 times more waste than its human residents. Unlike human waste, animal waste is usually not treated, and is stored in open lagoons that are prone to overflow during floods. When Such effluent contains many harmful bacteria and parasites, like E. coli and Toxoplasma. Forty percent of private wells tested in Iowa had coliform (fecal) bacteria present.[mfn].” Iowa Environmental Council[/mfn]

Along with bacteria, animal waste contains nutrients. While useful as fertilizer in small quantities, phosphorus and nitrogen are nutrients that when found in excess in water can cause algal blooms, which in turn starve aquatic life of oxygen. Leaks, runoff, spills and floods that are nutrient-rich will kill fish. From 1995 to 2013, approximately 800 manure spills killed over a million fish in Iowa.[mfn]Huber, Bridget and Mills, Lauren[/mfn],[mfn]Iowa Department of Natural Resources Fish Kill Database[/mfn] Just this month (April 2021), two large manure spills have already killed thousands of fish in Mud Creek in northwestern Iowa and Lotts Creeks in central Iowa.[mfn]Business Record[/fmn]

Hereford, Texas (Beef Capital of the US) pond polluted by cattle waste

Nitrate, a form of nitrogen, is also found in animal waste. Excess nitrate can cause cancer and birth defects, and this has become a growing concern in Iowa. Elevated nitrate levels in Iowa’s tap water could cause as many as 300 cancer cases per year in the state.[mfn]Temkin, Alexis and Evans, Sydney[/mfn]

When waste breaks down, it releases hydrogen sulfide, a gas that can cause neurologic damage and death at high concentrations. There have been incidents of midwestern CAFO employees dying from hydrogen sulfide poisoning after exposure to manure. Those who live near CAFOs are also at risk[mfn]Leonard, Stephanie[/mfn] As well, hydrogen sulfide can make its way to ground and surface water, raising naturally-occurring levels. Algal blooms also release hydrogen sulfide when they decompose.


CAFOs are supposed to be regulated through National Pollutant Discharge Elimination System (NPDES) permits, but the U.S. Government Accountability Office acknowledges the lack of available information on CAFOs.[mfn]Mittal, Anu[/mfn] Of those CAFOs that are recognized thus far, less than half have discharge permits, and the rules aren’t always enforced.[mfn]Huber, Bridget and Mills, Lauren[/mfn]

Soil conservation sign in Iowa’s Black Hawk Soil and Water Conservation District

In 2020, the Sierra Club called for a halt on new CAFOs, arguing against the costly externalities of CAFOs (such as manure spills and food recall due to bacteria), stating the health risks that are posed outweigh their profits. Existing CAFOs should be regulated more carefully to ensure waterways do not bear the costs of factory farming. Additionally, the Iowa Department of Natural Resources [DNR] could work with local leaders to identify all CAFOs, issue them appropriate discharge permits, and penalize non-compliers. Just like human waste, animal waste must be treated. One remedy is that CAFOs could utilize anaerobic digesters (large, oxygenless tanks) to break down animal waste, and then valuable biogas and fertilizer could be harvested from that.

Meanwhile, as the size of farms in Iowa are increasing, the number of farms are declining.[mfn]U.S. Department of Agriculture[/mfn] If CAFOs scale down, their effluent will be more manageable and new jobs on new smaller farms will be created to manage this larger number of ventures. Such smaller farms could connect with local consumers through community-supported agriculture programs (CSAs). Subsidies could be offered to farmers that apply sustainable techniques, such as letting cattle graze and responsibly managing manure.

Supervision and tracking runoff are also critical to addressing these issues. The Iowa DNR has a public database where viewers can report and track all known fish kills in the state, with information on their causes and severity. There is also a database with maps on water quality across Iowa. Tools like these are helpful aids in haring CAFO risks with the general public. Greater regulation of factory farms does not have to be “anti-agriculture;” but rather, a push to revive small family farms and make Iowa’s waters safe again.

A Missouri pig farm


“2020 305(b) Assessment Summary.” Iowa Department of Natural Resources, Feb. 2021. Accessed 4/18/21 by MS. https://programs.iowadnr.gov/adbnet/Assessments/Summary/2020

Eller, Donnelle. “Group Takes Aim at Large livestock Operations It Says Pollutes Iowa’s Water.” Des Moines Register, Feb. 2021. Accessed 4/15/21 by MS. https://www.desmoinesregister.com/story/money/agriculture/2021/02/09/iowa-lawmakers-join-environmentalists-calling-halt-large-livestock-operations/4436620001/

“Fish Kill Events.” Iowa Department of Natural Resources Fish Kill Database. Accessed 4/17/21 by MS. https://programs.iowadnr.gov/fishkill/Events

Huber, Bridget and Mills, Lauren. “Large Livestock Farms Spread Across Iowa, Threatening Waterways.” IowaWatch.org, May 2013. Accessed 4/15/21 by MS. https://www.iowawatch.org/2013/05/30/large-livestock-farms-spread-across-iowa-threatening-waterways/

“Iowa Ag News – Farms and Land in Farms.” U.S. Department of Agriculture, National Agricultural Statistics Service, Feb. 2020. Accessed 4/18/21 by MS. https://www.nass.usda.gov/Statistics_by_State/Iowa/Publications/Other_Surveys/2020/IA-Farms-02-20.pdf

“Iowa’s Private Wells Contaminated by Nitrate and Bacteria.” Iowa Environmental Council, April 2019. Accessed 4/16/21 by MS. https://www.ewg.org/interactive-maps/2019_iowa_wells/

Leonard, Stephanie. “Producers Respond to H2S Deaths.” Illinois Farmer Today, Nov. 2016. Accessed 4/16/21 by MS. https://www.agupdate.com/illinoisfarmertoday/news/livestock/producers-respond-to-h2s-deaths/article_2adc8f4b-5cd8-5f41-967b-fdfca0518e2c.html

“Manure Spills Lead to Fish Kills in Northern Iowa.” Business Record, April 2021. Accessed 4/16/21 by MS. https://businessrecord.com/Content/Default/All-Latest-News/Article/Manure-spills-lead-to-fish-kills-in-northern-Iowa/-3/248/93117

Mittal, Anu. “EPA Needs More Information and a Clearly Defined Strategy to Protect Air and Water Quality.” U.S. Government Accountability Office, Sept. 2008. Accessed 4/18/21 by MS. https://www.gao.gov/assets/gao-08-1177t.pdf

Temkin, Alexis and Evans, Sydney. “Nitrate in U.S. Tap Water May Cause More Than 12,500 Cancers a Year.” Environmental Working Group, June 2019. Accessed 4/16/21 by MS. https://www.ewg.org/research/nitrate-us-tap-water-may-cause-more-12500-cancers-year

Thessen, Greg. “Iowa Ag News – Hogs & Pigs.” U.S. Department of Agriculture, National Agricultural Statistics Service, Sept. 2019. Accessed 4/15/21 by MS. https://www.nass.usda.gov/Statistics_by_State/Iowa/Publications/Livestock_Report/2019/IA-Hogs-09-19.pdf

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