It is not the intent of the EPA or state regulatory authorities to require NPDES permits from pasture-based livestock operations. A pasture-based operation, where animals wander freely to and from areas for food and shelter, is not considered an Animal Feeding Operation (AFO). However, some pasture- and grazing-based operations may have confinement areas that qualify them as an AFO. Incidental vegetation such as weeds in a clear area of confinement such as a feedlot or pen would not exclude an operation from meeting the definition of an AFO.
Consider a winter feeding situation. The “no vegetation” criteria in the AFO definition is to be evaluated during the winter. Therefore, use of a winter feeding area to grow crops or other vegetation during periods of the year when animals are not present would not exclude the area from meeting the definition of an AFO, if animals are confined in the area for more than 45 days in a 12-month period. Conversely, a feeding area in a pasture that does not confine the animals (i.e., gate is open) and allows free access to rangeland or pasture would not qualify as a confined feeding area and would not be considered an AFO, regardless of the surface condition of the lot.
Whenever animal waste or contaminated water running off lots has the potential to reach surface waters, the farm could be regulated or a permit required. Animal waste runoff can cause water quality problems if it reaches surface waters, and allowing a discharge could make you subject to regulations. It is the responsibility of every livestock producer to ensure that runoff from their operation does not impact the environment.
Author: Chris Henry, Biological Systems Engineering, University of Nebraska