Concentrated animal feeding operations

In the terminology of the United States Environmental Protection Agency (EPA), a concentrated animal feeding operation (CAFO) is an animal feeding operation (AFO) that (a) confines animals for more than 45 days during a growing season, (b) in an area that does not produce vegetation, and (c) meets certain size thresholds. The EPA's definition of the term "captures key elements of the transformations" observed in the animal agriculture sector over the course of the 20th century: "a production process that concentrates large numbers of animals in relatively small and confined places, and that substitutes structures and equipment (for feeding, temperature controls, and manure management) for land and labor."

There are roughly 257,000 AFOs in the United States, of which 15,500 meet the more narrow criteria for CAFOs. The EPA has delineated three categories of CAFOs, ordered in terms of capacity: large, medium and small. The relevant animal unit for each category varies depending on species and capacity. For instance, large CAFOs house 1,000 or more cattle, medium CAFOs can have 300–999 cattle, and small CAFOs harbor no more than 300 cattle.

The table below provides some examples of the size thresholds for CAFOs:

The categorization of CAFOs affects whether a facility is subject to regulation under the Clean Water Act (CWA). According to the 2008 rule adopted by the EPA, "large CAFOs are automatically subject to EPA regulation; medium CAFOs must also meet one of two 'method of discharge' criteria to be defined as a CAFO (or may be designated as such); and small CAFOs can only be made subject to EPA regulations on a case-by-case basis." A small CAFO will also be designated a CAFO for purposes of the CWA if it discharges pollutants into waterways of the United States through a man-made conveyance such as a road, ditch or pipe. Alternatively, a small CAFO may be designated an ordinary animal feeding operation (AFO) once its animal waste management system is certified at the site.

Since it first coined the term, the EPA has changed the definition (and applicable regulations) for CAFOs on several occasions. Private groups and individuals use the term CAFO colloquially to mean many types of both regulated and unregulated facilities, both inside and outside the United States. The definition used in everyday speech may thus vary considerably from the statutory definition in the CWA. CAFOs are commonly characterized as having large numbers of animals crowded into a confined space, a situation that results in the concentration of manure in a small area.

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