1, page 7265) as a lot or facility (other than an aquatic animal production facility) where the following conditions are met: The definition of an AFO was developed by the EPA as a regulatory definition to delineate confined feeding of beef cattle, dairy cattle, horses, swine, sheep, poultry, or other livestock from pasture-based systems (grazing systems were not meant to be regulated by EPA) for enforcement of the Clean Water Act.
Concentrated Animal Feeding Operations are facilities that require federal National Pollutant Discharge Elimination System (NPDES) water quality permits, irrespective of size.
EPA did not explicitly differentiate AFOs by size in the Code of Federal Regulations, but is commonly understood as follows.
There are two conditions EPA and state regulatory authorities consider that if either are met, change the designation of an AFO to that of a CAFO.
This is often interpreted by regulators to mean that water runoff, manure, or process wastewater that can leave a facility and can come into contact with surface water, such as a road ditch, stream, river, pond, dam or similar watercourse, meets this definition, and thus pull medium AFOs into the permit program.