National Pollutant Discharge Elimination System (NPDES)

Animal Feeding Operations (AFOs)

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Animal Feeding Operations (AFOs) are agricultural operations where animals are kept and raised in confined situations. An AFO is a lot or facility (other than an aquatic animal production facility) where the following conditions are met:

  • 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
  • crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal growing season over any portion of the lot or facility.

AFOs that meet the regulatory definition of a concentrated animal feeding operation (CAFO) are regulated under the NPDES permitting program. The NPDES program regulates the discharge of pollutants from point sources to waters of the United States. CAFOs are point sources, as defined by the CWA [Section 502(14)] (PDF)(3 pp, 132 KB, About PDF). To be considered a CAFO, a facility must first be defined as an AFO, and meet the criteria established in the CAFO regulation.

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AFOs and Environmental Considerations

Manure and wastewater from AFOs have the potential to contribute pollutants such as nitrogen and phosphorus, organic matter, sediments, pathogens, hormones, and antibiotics to the environment.

For detailed information on environmental considerations associated with animal agriculture, see:

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Links to Other Resources

EPA Agriculture Resource Directory - EPA’s National Agriculture Center compiles agriculture-related information from across EPA.

Farm, Ranch, and Rural Communities Federal Advisory Committee (FRRCC) - EPA established the FRCCC in 2008 to provide independent policy advice, information, and recommendations to the EPA Administrator on a range of environmental issues and policies that are important to agriculture and rural communities.

Agriculture: Climate Change - Information on climate change related to agriculture.

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