Effect of Livestock Farming on Water Quality

Amy He ’25

Factory farming, also known as concentrated animal feeding operations (CAFOs), is a modern and industrial approach to produce animal products profitably and efficiently. In this approach, animals are raised in confined spaces and inhumane conditions. As a result, there are many surrounding issues, one of which is water pollution. Water pollution is a major environmental impact of CAFOs, where factory farming contaminates groundwater, lakes and streams — all of which are crucial sources of freshwater that humans rely on during a time of water scarcity (Water Scarcity | Threats | WWF, 2023).

Annually, livestock and poultry raised in the U.S. produces around 5 times the amount of waste than the entire U.S. population (Industrial Agricultural Pollution 101, 2022). However, while human waste is treated through municipal sewer systems that send waste to wastewater treatment plants, animal manure treatment is different. CAFOs handle the 1.4 billion tons of untreated livestock waste often through directly disposing it on land (Animal Feeding Operations - Uses of Manure | US EPA, 2020). Since the amount of manure greatly exceeds that of the ground can naturally absorb, they become runoff, flowing into nearby water sources. The waste, which carries antibiotic residue, chemicals, and pathogens, contaminates groundwater (EPA, 2005). Once the pollutants enter groundwater, they are extremely difficult to remove due to their water-soluble property. In the southern U.S., which has an abundance of poultry farms, up to a third of groundwater sources fall below the water quality of the U.S. Environmental Protection Agency (EPA)’s safe drinking standards for nitrate (Washingtonpost.com: Poultry’s Price, 2023). Nitrate, a form of nitrogen ample in chicken waste, can affect the function of hemoglobin if consumed in large quantities by humans, which is a protein that carries oxygen through blood.

In addition, manure contains nutrients, such as nitrogen, phosphorus, and potassium. This can improve crop growth in farms when used as organic fertilizer. However, when manure enters water systems, it can also lead to eutrophication and trigger algal blooms. Algae exploits the excess amount of nutrients and exponentially reproduces on water surfaces. Its overgrowth blocks sunlight for organisms below the water surface. Furthermore, as it dies off, aerobic bacteria decompose the algae, depleting more oxygen, starving large numbers of fish and shellfish (Effects of Manure on Fish Populations, 2019).

Ultimately, CAFOs have detrimental impacts on water resources through means such as runoff and algal blooms. Animal products, besides driving water pollution, also depletes water resources, as livestock drink water and consume crops such as soy, which is also raised with large amounts of water. Therefore, to protect and conserve our water resources, individuals should reduce their reliance on animal products, opting for plant based alternatives instead.

References

Animal Feeding Operations - Uses of Manure | US EPA. (2020, June 10). US EPA.

https://www.epa.gov/npdes/animal-feeding-operations-uses-manure

Effects of Manure on Fish Populations. (2019, September 26). UNL Water.

https://water.unl.edu/article/animal-manure-management/effects-manure-fish-populations

EPA. (2005). Protecting Water Quality from Agricultural Runoff.

https://www.epa.gov/sites/default/files/2015-09/documents/ag_runoff_fact_sheet.pdf

Industrial Agricultural Pollution 101. (2022, July 21). Nrdc.org.

https://www.nrdc.org/stories/industrial-agricultural-pollution-101

Washingtonpost.com: Poultry’s Price. (2023). Washingtonpost.com.

https://www.washingtonpost.com/wp-srv/local/daily/aug99/chicken1.htm

Water Scarcity | Threats | WWF. (2023). World Wildlife Fund.