The National Effluent Limitations Guidelines (NELG) and standards for feedlots and the National Pollutant Discharge Elimination System (NPDES) Permit Program for Concentrated Animal Feeding Operations (CAFOs) were issued on February 14, 1974, and March 18, 1976, respectively [2-6].
Under the NPDES CAFOs regulations, CAFOs were defined as facilities [or Animal Feeding Operations (AFOs)] with 1000 or more animal units (AU). An AFO with 300 to 1000 AU was defined as a CAFO if it discharged pollutants through a manmade device or if the pollutants were discharged to waters that ran through the facility or otherwise came into contact with the confined animals. The AFOs were not termed as CAFOs if they discharged only during a 25 year, 24 hour storm. Any AFO with less than 300 AU could be designated as a CAFO if it did not meet the discharge criteria specified and was determined to be a significant contributor of pollution [3-6].
The NELG issued in 1974 were applicable to those AFOs in specified sectors with as many as or more than 1000 AU that were to be issued an NPDES permit. It did not allow discharges of pollutants from CAFOs into the nation's waters except when a chronic or catastrophic storm caused an overflow from a AFO that had been designed, constructed, and operated to contain manure, process wastewater, and runoff resulting from a 25 year, 24 hour storm [3-5].
The goals for the above regulations were for owners and operators of AFOs to take action so that pollution could be minimized in the areas where the livestock productions were operated. All AFOs should develop and implement technically sound, economically feasible, and sitespecific comprehensive nutrient management plans (CNMPs) in order to accomplish the objective. The actions included development and implementation of CNMPs, promotion of voluntary and incentive-based programs, improvement of the existing regulatory program, and development of technologically sound technologies.
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