A Concentrated Animal Feeding Operation (CAFO) is the designation given to large-scale agricultural facilities that raise a high density of livestock or poultry. These operations represent a significant shift from traditional grazing, housing a massive number of animals in confinement where feed is brought to them. The goal is the efficient production of meat, milk, and eggs. Due to the immense concentration of animals, CAFOs generate vast amounts of manure and wastewater, classifying them as industrial facilities with the potential to impact the environment. This makes CAFOs a focal point for regulatory bodies concerned with environmental protection and public health.
Operational Definition and Thresholds
The legal distinction between an Animal Feeding Operation (AFO) and a CAFO rests on the number of animals confined and the potential for waste discharge. An AFO is defined as a facility where animals are confined for at least 45 days in any 12-month period, and where vegetation cannot be sustained. A CAFO is a specific subset of an AFO that meets a regulatory threshold for size or directly discharges pollutants into navigable waters.
This classification system uses the Animal Unit (AU) metric, where one AU is equivalent to 1,000 pounds of live animal weight, to standardize scale across different species. A Large CAFO meets or exceeds the threshold of 1,000 AUs, translating to 1,000 beef cattle or 700 mature dairy cows. These large operations are automatically subject to federal environmental regulations due to their scale.
Medium CAFOs confine between 300 and 999 AUs, such as 200 to 699 dairy cows. They are only designated as a CAFO if they meet specific discharge criteria, which involves having a manmade conveyance that carries manure or wastewater to surface water. Small AFOs, housing fewer than 300 AUs, are not regulated as CAFOs unless a regulatory authority designates them as a significant contributor of pollutants. The size and discharge criteria determine which operations must comply with the most stringent environmental rules.
Regulatory Oversight and Permitting
CAFOs are legally classified as point sources of pollution because waste is collected and discharged from a single, definable location, such as a pipe or ditch. This classification places them under the jurisdiction of the Clean Water Act, which mandates control over discharges into waters. The primary mechanism for governmental control is the National Pollutant Discharge Elimination System (NPDES) permit program, required for any CAFO that discharges or proposes to discharge pollutants.
The permitting process manages waste streams and ensures compliance with effluent limitations to prevent unauthorized pollution. Large CAFOs must obtain an NPDES permit, while medium and small operations must seek a permit only if they meet specific discharge criteria. A central component of the permit is the requirement for a site-specific Nutrient Management Plan (NMP) that the operator must develop and implement.
The NMP is a mandated compliance document detailing protocols for managing all manure, litter, and process wastewater. It requires annual testing of the manure and wastewater for nitrogen and phosphorus content, alongside five-year soil testing in application fields. The plan must establish site-specific conservation practices, such as buffers or setbacks from waterways, to prevent runoff. These measures ensure waste is applied to land at an agronomic rate, matching the nutrient needs of crops to avoid soil saturation and nutrient runoff.
Key Environmental Consequences
The high concentration of waste produced by CAFOs affects water quality through the release of nutrients like nitrogen and phosphorus. Manure is often stored in large, open-air lagoons that can leak or overflow during severe weather, carrying contaminants into nearby waterways. This nutrient overload fuels the excessive growth of algae, a process called eutrophication, which impacts aquatic ecosystems.
When algal blooms die, bacteria consume dissolved oxygen, leading to hypoxia, or “dead zones,” which cannot sustain most fish and marine life. The Gulf of Mexico experiences one of the largest dead zones, heavily influenced by agricultural runoff. Runoff from CAFOs also introduces pathogens, such as E. coli, and antibiotics into drinking water sources and recreational waters.
Air quality is compromised by gases emitted from the decomposition of animal waste. Ammonia, hydrogen sulfide, and methane are the most common gaseous pollutants released from manure storage lagoons and barns. Ammonia is a respiratory irritant, and hydrogen sulfide is a toxic gas that can cause neurological problems. Methane is a potent greenhouse gas, contributing to climate change.
The land application of manure, while intended as a beneficial use, becomes challenging when the amount of waste exceeds the land’s capacity to absorb nutrients. Repeated application can saturate the soil with phosphorus, which is carried away in runoff during rain events. This soil nutrient saturation increases the risk of water pollution, requiring careful management to balance waste disposal with crop nutrient needs. The scale of waste production often necessitates transporting manure off-site, extending the potential for environmental impact.