Lax oversight of hog CAFOs harms endangered species, study finds

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Large concentrated hog farms that send manure contamination into local waterways not only impact human health but threaten the existence of more than a dozen endangered species, according to a new study. 

Researchers examined the overlap between endangered species and hog concentrated animal feeding operations, CAFOs, in the three highest hog-producing states — Iowa, Minnesota and North Carolina — and found that 17 aquatic species that are endangered, threatened, or under review for listing share watersheds with hog CAFOs. For 10 of these species, the shared watersheds are listed as “critical habitat,” meaning areas that are essential to the species’ survival. 

The researchers say CAFO manure leaching into waterways further threatens these species given the increased nutrients such as phosphorus and nitrogen that CAFOs can discharge into water, which can slow species’ development and growth, impair feeding and spawning areas, and kill species by reducing oxygen and spurring algal blooms. 

They allege that lax federal oversight means regulators in charge of protecting these species are not able to fully account for CAFO pollution, which can also harm human health via excessive nitrates in waterways and air pollution. 

“Increased transparency and reporting from CAFOs regarding their locations, manure management practices, and pollution discharges will be critical for improved protection of sensitive species,” the authors wrote. 

“Haphazard and limited” regulation 

The researchers used a mix of state and federal data to estimate the CAFO overlap with endangered or threatened species. The 17 aquatic species included nine freshwater mussels, six fish, a snail and an amphibian. Eleven species are federally endangered, four are threatened, one is proposed as threatened, and another is under review. They found six of the species have more than 100 hog CAFOs within their habitat ranges. 

Kemp Burdette, executive director and riverkeeper for Cape Fear River Watch, said “of course long-term increases in bacteria, nutrients and other pollutants from CAFOs being continually discharged into a watershed are going to impact every species — certainly endangered species.” 

Burdette added that the study is likely underestimating CAFO-driven pollution in North Carolina since it is only looking at hog waste. “North Carolina is now the leading producer of poultry in the United States … so, in addition to the hog farms, that’s more nutrients, more bacteria, more heavy metals, more antibiotics, and all of the things that could impact endangered species.” 

Mustafa Saifuddin, lead author of the new study and a staff scientist with the Sustainable Food and Farming Program at Earthjustice, said it’s important to examine CAFOs near endangered species because the facilities are not all regulated. 

According to the most recent US Environmental Protection Agency (EPA) data from 2024, only 32% of US CAFOs have National Pollutant Discharge Elimination System (NPDES) permits, which are required by the Clean Water Act for facilities that discharge water pollution. 

“The regulation of water pollution from CAFOs is haphazard and limited and many are able to discharge water pollutants without getting federal permits,” Saifuddin said. 

“The regulation of water pollution from CAFOs is haphazard and limited.” – Mustafa Saifuddin, Earthjustice 

NPDES permits are issued by state regulatory agencies. Each state varies in its CAFO NPDES permitting. For example, Iowa, which has the most CAFOs of any state, has issued NPDES permits for about 4% of the facilities, according to federal estimates. 

The EPA acknowledged this lack of oversight in a 2022 report. “While many waters are affected by pollutants from CAFOs, many CAFOs often claim that they do not discharge, and EPA and state permitting agencies lack the resources to regularly inspect these facilities to assess these claims, particularly since discharges often only occur during certain weather conditions,” the report said. 

Federal CAFO subcommittee stopped meeting 

Saifuddin said the study was prompted by a petition from dozens of environmental and health groups in 2022 urging the EPA to increase oversight of CAFOs. It was well-established that “these facilities are contributing to water, air pollution, and climate change after decades of studies and concerns raised by frontline communities, we don’t need more analysis there,” Saifuddin said, adding that there was little data on CAFO pollution and endangered or threatened species. 

In response to the petition, the agency created a federal advisory committee to give recommendations for addressing CAFO water pollution. 

Alexis Andiman, a senior attorney at Earthjustice who was on the committee along with other representatives from other environmental groups, industry state agencies, said they “met a number of times but have not met since the Trump administration took office.” The EPA lists the committee as “inactive.” 

“EPA and state agencies just don’t have the resources necessary to ensure that each discharging CAFO has the required permit, which is why we urged the EPA to shift the burden so CAFOs would have to either obtain a permit or explain that they don’t require one rather than EPA and state agencies having to go out and prove that CAFOs are discharging,” Andiman said. 

US Fish and Wildlife acknowledges some threats 

Despite a lack of federal monitoring and regulation for a vast majority of CAFOs, the US Fish and Wildlife Service (FWS), which oversees endangered and threatened species, had already enlisted CAFOs as threats to two of the threatened species in the new study — the Neuse River waterdog and Atlantic pigtoe — and two of the endangered species — dwarf wedgemussel and Carolina madtom. 

An FWS spokesperson said in an email that it doesn’t comment on research authored outside the agency. 

Saifuddin and colleagues recommended that, in addition to federal agencies more tightly regulating and monitoring CAFOs, operations could reduce the amount of animals they hold and bolster their manure storage.

Featured image: Neuse River Waterdog, listed as threatened. (Credit: USFWS)