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Hog waste has many contaminants, raising concerns about nearby water quality, but a study out of ECU seeks solutions

Manure lagoons on hog farms like this one in eastern North Carolina flooded after Hurricane Floyd swept through in 1999, creating environmental and health concerns for nearby rivers.
John Althouse
AFP/Getty Images
Manure lagoons on hog farms like this one in eastern North Carolina flooded after Hurricane Floyd swept through in 1999, creating environmental and health concerns for nearby rivers. Farmers are worried that the scenario will repeat after Hurricane Florence hits this week.

Images of Hurricane Floyd show neighborhoods and farms with water up to the roof. Some photos even show pigs on top of their farmhouses. The hurricane swept through the region in 1999, causing significant damage to swine operations and flooding waste lagoons, raising concerns among environmentalists about the bacteria in hog waste contaminating waterways. North Carolina is home to nearly 10 million hogs that produce 10 billion gallons of manure each year, with Wayne and Duplin Counties home to most of the state’s hog farms.

A report from the Environmental Working Group (EWG), a nonprofit environmentalist organization, finds that 156 North Carolina hog and chicken farms are in or near floodplains.

Biowaste from hog farms is stored in large lagoons that are not often covered, meaning heavy rainfall could lead to a spill.

"You have these open large pits of manure, essentially. So, when they flood it’s really easy for all that manure to end up in nearby waterways," Anne Schechinger, a director at EWG, said.

There have been spills in recent years. NC Policy Watch reported in 2021 that a Jones County farm spilled an estimated 1 million gallons of hog waste into Tuckahoe Creek, a tributary of the Neuse River. To be clear, the water that came from your tap is fine, but a spill could cause complications for municipal and county water systems and pose dangers to nearby wildlife. Hog manure contains phosphorous and nitrate, both compounds that can negatively affect health if consumed.

"Spills like these are what’s really contributing to algae blooms. They can be toxic, and these toxins can be scary for animals," Schechinger said. "The phosphorous from manure getting in the water and then feeding these algae blooms is a drinking water issue, but it’s also a really big recreational issue."

In Duplin County there are more than 1,000 hog farms, and in Wayne, there’s more than 350. Of these, 41 farms are in or near floodplains, according to EWG.

The state acknowledges the risk that flooding and hog farms pose when paired together. In 2000 after Hurricane Floyd, the state launched a program to buy out hog farms in floodplains. The program is in its fifth phase right now and it aims to reduce the potential for pollution from concentrated animal feeding operations, or CAFOs, according to the North Carolina Department of Agriculture, who administers the program.

The state bought out 43 hog farms in total over the years, but EWG asserts that 59 hog farms remain in flood-prone areas.

When it comes to preventative measures, the buyback program is voluntary and farmers are required to report spills to NCDEQ, but at ECU a study is in development to measure contamination and design solutions.

Guy Iverson is a wastewater researcher at East Carolina University. He’s developing a study that will measure potential contamination around one farm in Harnett County. That data will be used to develop and test practices to contain contaminants. The study is a partnership between ECU, Waterkeepers, Butler Farms and the state.

He said that nitrate was the most common compound they found during early field visits.

"And in the pilot study we were seeing that nitrate is the kind of most dominant species of nutrient that was present and phosphorous and E. coli was actually pretty good there," Iverson said.

He noted there are likely several sources from the farm that contribute to these readings: fertilizers, animal waste, human waste and stormwater. The second phase of the study will include designing and installing systems in response to phase one findings.

Iverson suspects reducing nitrate will be the focus. Converting nitrate into dinitrogen gas, which is in the air we breath, would involve injecting carbon into the lagoon so that it mixes and combines with the nitrate.

The farm Iverson is studying is unique. It’s run by an eco-conscious farmer and the lagoons have a physical cap over them.

"You can actually go out there and walk on it," he said. "It’s almost like walking on a waterbed."

The cap system is intended to reduce odors and support an anaerobic digester. The digester turns gas produced by the hog waste into energy.

"The idea is if we can harvest those gases, they’re just king of sitting there, we can run them through the digestion process and then convert them into natural gas that can be used to power homes," he said.

Iverson will begin making field visits this summer.

Ryan is an Arkansas native and podcast junkie. He was first introduced to public radio during an internship with his hometown NPR station, KUAF. Ryan is a graduate of Tufts University in Somerville, Mass., where he studied political science and led the Tufts Daily, the nation’s smallest independent daily college newspaper. In his spare time, Ryan likes to embroider, attend musicals, and spend time with his fiancée and two cats.