Animal Feeding Operations:
The term "animal feeding operation" (AFO) is defined in the Code of Federal Regulations 40 CFR 122.23 (b)(1) as a lot or facility where 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."
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Concentrated Animal Feeding Operation:
An AFO is a "concentrated animal feeding operation" or CAFO if it meets the regulatory definition of CAFO or if it is designated as a CAFO. A CAFO is defined in 40 CFR 122.23 appendix B as "an animal feeding operation where more than 1,000 'animal units' (as defined by the regulation) are confined at the facility; or more than 300 animal units are confined at the facility and either one of the following conditions are met: pollutants are discharged into navigable waters through a man-made ditch, flushing system or other similar man-made device; or pollutants are discharged directly into waters of the United States which originate outside of and pass over, across, or through the facility or otherwise come into direct contact with the animals confined in the operation."
In addition, the NPDES permit issuing agency may, after conducting an on-site inspection, designate an animal feeding operation of any size as a CAFO based on a finding that the facility "is a significant contributor of pollution to waters of the United States." A facility with 300 animal units or less, however, may not be designated as a CAFO under this authority unless pollutants are discharged from a man-made conveyance or are discharged directly into waters passing over, across or through the facility or that otherwise come into direct contact with the confined animals [40 CFR 122.23 (2)].
The regulations also provide that no animal feeding operation is a CAFO under the regulatory definition if it discharges only in the event of a 25-year, 24-hour or larger storm event.
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EPA has recently revised its rules about animal feeding operations and clarified its definition of a Concentration Animal Feeding Operation ( see revised definition of CAFO ). A CAFO is required to have a discharge permit (NPDES permit). Operations that meet the AFO definition and are above 1,000 animal units are automatically considered CAFOs, and need a permit. Smaller operations, however, can be designated a CAFO, and may be required to get a permit unless they can eliminate the runoff of pollutants from their operations into Utah's waters.