National Pollutant Discharge Elimination System (NPDES) Animal Feeding Operations

OVERVIEW

The NPDES program regulates the discharge of pollutants from point sources to waters of the United States. Concentrated Animal Feeding Operations (CAFOs) are point sources, as defined by the CWA [Section 502(14)]. To be considered a CAFO, a facility must first be defined as an Animal Feeding Operation (AFO).

Animal Feeding Operations (AFOs) are agricultural operations where animals are kept and raised in confined situations. AFOs generally congregate animals, feed, manure, 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. Animal waste and wastewater can enter water bodies from spills or breaks of waste storage structures (due to accidents or excessive rain), and non-agricultural application of manure to crop land. AFOs that meet the regulatory definition of a concentrated animal feeding operation (CAFO) have the potential of being regulated under the NPDES permitting program.

An animal feeding operation (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.

An operation must meet the definition of an AFO before it can be defined or designated as a concentrated animal feeding operation (CAFO). Previous EPA regulations based the definition of CAFOs on the number of "animal units" confined. EPA no longer uses the term "animal unit," but instead refers to the actual number of animals at the operation to define a CAFO. Click here to view a brief summary of how the regulations define Large, Medium, and Small CAFOs.