IDEA (Increasing Diversity and Enhancing Academia) student Emily Robinson conducted a research project this summer on nitrate contamination in Sampson County.
Her summary report:
Nitrate Contamination in Sampson County Warrants a Closer Look
Sampson County, NC, is pretty high up on the hog leaderboard- it’s one of the top counties in a state that already leads the nation in hog production (North Carolina is second only to Iowa). This wasn’t a claim to fame that Sampson County could always boast about, though. North Carolina wasn’t dominant in the industry until around 1985. Until then, NC hog production was largely the job of small facilities owned and operated by independent farmers. Then large corporations started setting up shop. These new hog farms were larger, denser operations that big companies like Smithfield Foods contracted farmers to run. The animals in these operations don’t roam around in green pastures, but rather are kept in close, confined quarters. Hence the label “CAFO,” short for “Confined Animal Feeding Operation.” The CAFO boom propelled North Carolina from fifteenth place in hog production for the nation in 1985 to second place in 1998. However, it wasn’t the whole state that received an influx in piggy co-inhabitants. Rather, the CAFO growth was concentrated in the Piedmont region. Largely urban and poor, the Piedmont offered cheap land and lax regulations, a winning deal for hog farmers.
Nearby Piedmont residents, on the other hand, started realizing that they might be on the losing end of the deal. With a massive amount of animals comes a massive amount of waste; hogs generate poop, and that poop has to go somewhere. The solution to this problem has two parts: lagoons, and fields. First, hog waste is piped into massive open pits within the CAFO property, called lagoons, where it undergoes anaerobic decomposition. The waste can then be sprayed onto nearby fields. The rationale behind the poop spraying is that hog waste contains nutrients, like nitrates, that can serve as natural fertilizer for crops. The problem is, the spray doesn’t just go into the soil- first, it hits the air. From there, it drifts with the wind, ending up in the air around people’s houses, schools, and churches. The most noticeable effect from this is, of course, the smell; residents near CAFOs report a nauseating smell so thick in the air around their house that they can’t go outside or open windows. Researchers have also uncovered other effects that might not be as noticeable to the average resident. Asthma rates, along with other respiratory illnesses, are increased in areas near CAFOs, and so are rates of mental illness like anxiety and depression.
All this makes it sound like a CAFO isn’t something you would want to be neighbors with. Unfortunately, corporations disproportionately place CAFOs in areas with largely low income, non-white residents: populations that historically lack the political power to demand regulations to keep undesirable operations out of their neighborhoods. Some might make the argument that CAFOs are simply located in rural areas, and rural areas in North Carolina just happen to be poor and non-white. But while the Piedmont is generally poorer, and less white, than the rest of the state, a study published in 2000 showed that even when adjusting for population density (or ‘rural-ness’), CAFOs were still more likely to be in areas with lower percentages of white residents, and areas with lower incomes. These areas are also less likely to have good health services, compounding the problem of negative health effects.
This fraught history brings us to Sampson County, present day, where over a fifth of the residents live in poverty, and about 50% of the residents are non-white. The number of hogs it produces each year is second in the state only to Duplin County, depending on the year. My summer research project was to look at the wells in Sampson County and see if contaminants in the well water could be tied to proximity to CAFOs. Wells are an important part of the county’s water supply: over a quarter of North Carolinians rely on private wells for drinking water, and that number is highest in rural areas, like Sampson County. However, unlike the public water supply, private wells aren’t regulated by the EPA. If your water comes from the city tap, then the EPA has set out maximum contaminant levels for that water, and makes sure every drop coming out of your faucet is below that maximum. If your water comes from a private well, maintaining the safety of your water is your job. You can get your well tested for a laundry list of contaminants by the Sampson County Department of Environmental Quality, though, and that’s where I got my data. The NC Department of Health and Human Services has a record of all the wells that the Sampson Co DEQ has tested. This includes the test results, the address of the well, the date they were tested, and a few other details.
I decided to narrow down the list of contaminants and focus on nitrates. Nitrates are present in very high levels in animal waste, and are often the first indicator of animal waste contamination. While the hog poop might be contained for storage in lagoons, those lagoons aren’t leak proof. Studies have shown that soil type affects how well lagoons hold the waste in- soils high in clay content are less likely to allow leaks, while sandy soils might let more waste slip. If nitrates do infiltrate into the groundwater that wells draw from, the consequences can range from hypertension, to stomach cancer, to “methemoglobinemia,” a disease that kills infants.
I looked at the nitrate test results for around 350 wells, using tests that dated back to 2014. These wells would need to be mapped to see their proximity to CAFOs, so I used a tool that allowed me to match the given addresses with latitude and longitude coordinates that the mapping software could use. I ended up with slightly under 300 wells whose addresses could be confidently matched to a set of coordinates. Once I had the wells, I needed the CAFOs. Data on animal operations in Sampson County was publicly available from the NC Department of Environmental Quality, though CAFOs were not specifically labeled. The EPA defines CAFOs using criteria of the number of animals and the way waste is dealt with, so I used the information on animals allowed in the facility and the presence of lagoons that the DEQ provided with its data to single out the CAFOs. From there, I mapped the wells and the CAFOs, and used the mapping software to find the distance between each well and the closest CAFO to it.
What I found was that of all the wells tested, fifteen exceeded the EPA limit for nitrates in public drinking water. All fifteen of the wells that exceeded this limit were within 1.8 miles of a CAFO. When I overlaid the CAFOs onto a map of the soil types in Sampson County, I found that most of the CAFOs were resting on sandy soil, the type most likely to allow waste leakage into groundwater. This seems to indicate that there might be some waste water contamination in Sampson County. However, when nitrate concentration was plotted versus distance to nearest CAFO, the correlation between the two appeared to be very low. The natural next step for this project is a more nuanced study. Further examination of Sampson County should take into account that the wells are in close proximity to multiple CAFOs, not just their closest neighbor. These wells might be receiving contamination from multiple directions. Additionally, the hog waste sprayed onto nearby fields could complicate matter if the nitrates from that spray seep into the groundwater. A closer look at these elements could help clarify how, exactly, CAFOs are affecting their neighbors in Sampson County.