Manure Management in Iowa from CAFO Ops to Fertilizer: Nitrates Pollute Drinking Water and Runoff Can Feed Harmful Algae Blooms: Inside Climate News Report

       This post is based on an investigative report by Inside Climate News and Sentient Media. Inside Climate News, though biased as the name implies toward climate activism, also does some good investigative environmental journalism.

     There are nearly 8,000 concentrated animal feeding operations (CAFOs) in Iowa. Now, the former coordinator of the state’s livestock regulating body, Gene Tinker, also a pork farmer with a CAFO lot, says the Iowa DNR’s regulatory approach and data collection about livestock waste are inadequate. There is a clear need for better manure management to address environmental risks and protect water quality. The DNR requires farmers to submit documents outlining their plans for spreading livestock manure during the permitting process, but doesn’t collect records of where and how much manure is actually spread. However, he says that hauling companies that contract with CAFOs to apply manure have records that could easily be digitized about manure spreading details.

     The nitrogen and phosphorus present in manure that is not used by plants can end up in surface water, and eventually in groundwater. It poses a threat to drinking water in some places due to nitrates. In surface water, manure runoff can feed harmful algae blooms. The state is behind the curve in optimizing manure management.

“…despite a nearly 50 percent increase in nitrate levels in Iowa’s waterways and mounting evidence linking agricultural practices to pollution, Iowa has not substantively updated its fertilizer and manure rules since 2002, except for a 2009 amendment regulating when manure could be applied to snow-covered ground.”

     The state, however, says that its requirements for manure management meet or exceed federal requirements.

“Ninety-nine percent of farm animals in the U.S. are raised in CAFOs, which are typically characterized by shed-like structures that house hundreds to thousands of animals. Iowa alone is home to approximately 23 million hogs, nearly all of which are raised in confinement, and which produce an estimated 110 billion pounds of manure each year.”

     Each facility is required to submit detailed plans every four years.

“Manure management plans require Iowa livestock producers to specify the exact fields for manure spreading and demonstrate that the nutrients in the manure won’t exceed the needs of crops and pollute waterways.”

     Only about 7 percent of all active plans in the state are inspected on-site by DNR personnel. Manure application records from haulers are reviewed during those inspections. Tinker argues convincingly that those records should be required to be submitted so the state would have them for all facilities. Apparently, it is common for the same field to have planned manure application by several CAFOs across multiple plans. This can increase the risk of over-fertilization and runoff. However, the plans account for the totals to be applied below thresholds.

“In 2023, the department began operating a public database to track facility submissions, upload files and ensure plans are turned in on time. But there is still no system for aggregating data from multiple plans to get a better understanding of the big picture, according to current and former DNR staff.”

     Tinker argues that without tabulating all the hauler application records, there is no way to know important information, for instance, how much nitrogen and phosphorus are applied every year in this state.

“In manure management plans, estimated phosphorus demand is based on soil testing and a recently updated soil loss equation, but the rates used to predict nitrogen demand are woefully outdated, Tinker said.

     Iowa has some of the highest nitrate pollution rates in the country. Nitrate is associated with higher lethal cancer risks and life-threatening issues for children, including methemoglobinemia, also known as blue baby syndrome. Iowa has the second-highest cancer rate in the nation and is one of only two states where cancer rates are rising. Agricultural pollution, including nitrate pollution, is highly suspect.

   Des Moines Water Works operates a nitrate removal system that sometimes struggles, especially in the summer, when nitrate levels on the water can be high. In the summer, it can cost $10,000 per day to run the facility. The high nitrate loads triggered lawn watering bans in the summer.

“…the majority of nutrient pollution in the state is indirect, leaching off fields treated with excess fertilizer. Since publishing its nutrient reduction strategy in 2014, Iowa has seen increased adoption of voluntary conservation practices to reduce nutrient loss, but only slight improvement in the nutrient levels in its waterways.”

     As Tinker notes, the state can and should do more to quantify and verify nutrient application data.

     

 

References:

 

Factory Farms in Iowa Generate 110 Billion Pounds of Manure Per Year. No One Tracks Where It’s Going. Anika Jane Beamer and Nina B. Elkadi. Inside Climate News. December 4, 2025. Factory Farms in Iowa Generate 110 Billion Pounds of Manure Per Year. No One Tracks Where It’s Going. - Inside Climate News

Pollution, Not Drought, Prompts Lawn-Watering Ban in Des Moines: It’s a first for the Central Iowa Water Works, which is worried about maintaining compliance with EPA nitrate standards. Anika Jane Beamer. Inside Climate News. June 19, 2025. Pollution, Not Drought, Prompts Lawn-Watering Ban in Des Moines - Inside Climate News