The EPA defines AFOs (animal feeding operations) and CAFOs (concentrated animal feeding operations). In the Clean Water Act, Congress authorized the EPA to regulate concentrated animal feeding operations as potential “point sources” prohibited from discharging pollutants into “waters of the United States” without a permit.[1] The purpose of the agency’s designations is to categorize operations according to the amounts of manure generated and the accompanying water pollution risks.[2]
The Clean Water Act, 33 U.S.C. § 1251 et seq.
U.S. Environmental Protection Agency (2012) NPDES Permit Writers’ Manual for Concentrated Animal Feeding Operations, EPA 833-F-12-001.
According to the EPA:
“Animal feeding operation (AFO) means a lot or facility (other than an aquatic animal production facility) where the following conditions are met:
(i) Animals (other than aquatic animals) have been, are, or will be stabled or confined and fed or maintained for a total of 45 days or more in any 12-month period, and
(ii) Crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal growing season over any portion of the lot or facility.”[1]
For an exhaustive exploration of the definitions, requirements, and examples of AFOs (and non-AFOs) see the EPA’s NPDES Permit Writers’ Manual for CAFOs.[2]
40 CFR § 122.23(b) Concentrated animal feeding operations
U.S. Environmental Protection Agency (2012) NPDES Permit Writers’ Manual for Concentrated Animal Feeding Operations, EPA 833-F-12-001, pp. 2-5.
According to the USDA and EPA, as written in a joint strategic report: “AFOs congregate animals, feed, manure and urine, dead animals, and production operations on a small land area. Feed is brought to the animals rather than the animals grazing or otherwise seeking feed in pastures, fields, or on rangeland.”[1]
USDA & EPA (1999) U.S. Department of Agriculture & U.S. Environmental Protection Agency Unified National Strategy for Animal Feeding Operations. https://www.epa.gov/sites/default/files/2015-10/documents/exexsum.pdf
The term CAFO is sometimes used to reflect the EPA’s precise regulatory definition (see question below). The term is also commonly used to describe any industrialized animal agriculture operation or factory farm.[1]
As an example of the broader definition, the USDA defines a CAFO as: “A facility where large numbers of farm animals are confined, fed and raised such as cattle feedlots, hog production facilities and closed poultry houses.”[2]
James M. MacDonald & William D. McBride (2009) The Transformation of U.S. Livestock Agriculture: Scale, Efficiency, and Risks, USDA Economic Research Service, Economic Information Bulletin No. 43, pp. 3-4. [“While the EPA has a precise definition for a CAFO, the term is now used broadly and interchangeably with terms like industrialized agriculture or factory farms to refer to a production process that features confined feeding of large herds or flocks…”]
concentrated animal feeding operations (n.d.) USDA National Agricultural Library Agricultural Thesaurus.
The EPA classifies CAFOs as a sub-category of AFOs. It further divides CAFOs into large, medium, and small sizes depending on the numbers of animals, the potential for dispersing pollutants into the waters of the United States, and in some cases, the types of manure handling systems.[1] The agency’s parameters for categorizing AFOs were created when it established the National Pollutant Discharge Elimination System (NPDES) pursuant to the Clean Water Act.[2]
Operations that meet the animal number threshold for Large CAFO are always designated as such. To be designated as a Medium CAFO, an operation must meet both the animal number thresholds and also be discharging pollutants into the waters of the U.S.[3] A Small CAFO has fewer than the animal number thresholds for a Medium CAFO, while also discharging pollutants into the waters of the U.S.
40 CFR §122.23 Concentrated animal feeding operations
40 CFR Part 122 EPA Administered Permit Programs: The National Pollution Discharge Elimination System [“Concentrated animal feeding operations” defined at 40 CFR § 122.23]
40 CFR § 122.23(b)(6)(ii)
Pursuant to the Clean Water Act and the implementation of the National Pollutant Discharge Elimination System (NPDES), the States follow the same animal threshold figures for CAFOs as established by the EPA.[1,2]
However, the potential for discharging pollutants is also a key factor when designating an animal feeding operation as a CAFO,[3] and this determination is often at the discretion of state regulators. If an operation does not meet the Large CAFO animal thresholds, a determination that the operation is a CAFO will depend on state environmental agencies making an assessment that it is a significant contributor of pollutants into U.S. waterways.
EPA regulations provide factors to consider: size, location, slope, vegetation, rainfall, and others that affect the likelihood or frequency of discharge of animal waste. But they also state that “no AFO shall be designated a CAFO unless there has been an on-site inspection.”[4] And the EPA acknowledges that state agencies lack the resources to inspect facilities to assess producers’ claims that they do not discharge, and the “regulations contain definitions, thresholds and limitations that make it difficult to compel permit coverage, limit the discharge of pollutants under certain circumstances, and enforce requirements even when discharges have been established.”[5]
33 U.S.C. § 1251(b) Clean Water Act, Congressional declaration of goals and policy
40 CFR § 122.23 Concentrated animal feeding operations
40 CFR § 122.23(c) How may an AFO be designated as a CAFO?
40 CFR § 122.23(c)(2)(3)
U.S. EPA (May 2022) EPA Legal Tools to Advance Environmental Justice, EPA Publication No. 360R22001, p. 75.
The term feedlot is generally used to describe confinement facilities where cattle are fattened for about 6 months prior to slaughter.[1-3]
Most beef cattle spend some portion of their lives grazing on pasture. The majority end up tightly confined on feedlots for the “finishing” stage. Most feedlots are outdoors on bare ground; areas with higher rainfall tend to use smaller indoor feedlots.[4]
Cattle usually spend the final 3 to 6 months (sometimes as many as 10 months) of their 18 to 22- month lives on feedlots. They rapidly gain weight (2.5 to 4 pounds a day) on a diet composed of 70-90% grain and protein concentrates that includes corn, wheat, or barley and by-products such as distillers’ grains.[5,6] Some feedlots have fewer than 100 cattle, though the great majority of cattle raised for beef are on feedlots with more than 2,500 animals.[7]
feedlot (n.d.) USDA National Agricultural Library Agricultural Thesaurus. [“Confinement facilities where cattle are fed to produce beef for the commercial trade.”]
Note: The EPA defines feedlots more broadly as a “Lot or building or a group of lots or buildings used for the confined feeding, breeding or holding of animals. This definition includes areas specifically designed for confinement in which manure may accumulate or any area where the concentration of animals is such that a vegetative cover cannot be maintained. Lots used to feed and raise poultry are considered to be feedlots. Pastures are not animal feedlots.”] See, U.S. EPA (2012) NPDES Permit Writers’ Manual for Concentrated Animal Feeding Operations, EPA 833-F-12-001, Glossary 7.
For more info on feedlots see, Cattle and Dairy Housing & Space Allotments
Grandin, T. (2016). Evaluation of the welfare of cattle housed in outdoor feedlot pens. Veterinary and Animal Science, 1, 23-28, p. 24. [“Today cattle feeders in these high rainfall areas have constructed indoor facilities with either a concrete slatted floor or a bedded pack.”]
USDA Economic Research Service (2023) Cattle and Beef, Sector at a Glance. https://www.ers.usda.gov/topics/animal-products/cattle-beef/sector-at-a-glance/
Western Institute for Food Safety and Security at Univ. of California – Davis and the U.S. FDA (2016) Food Animal Production Manual, pp. 22-33.
USDA (2024) 2022 Census of Agriculture, Table 12.
All feedlots meet the EPA definition of an AFO. Feedlots with 1,000 or more cattle are considered Large CAFOs.[1]
40 CFR § 122.23 Concentrated animal feeding operations