• In short, the linear approach expresses field-specific maximum rates of application in terms of the amount of nitrogen and phosphorus from manure allowed to be applied. The narrative rate approach allows application rates to be determined based on the total amount of nutrients combined with a specific, quantitative method for calculating the amount of manure allowed to be land applied.

  Without going into more specifics, the narrative approach allows the most flexibility and appears to most closely resemble many state manure nutrient management plan regulations.

  If there is a substantial change to an NMP, the NPDES permit must be modified and the EPA or state must notify the public and make the proposed changes available for public comment. Substantial changes include, but are not limited to, the addition of new land for manure application and the addition of any new crop.

  CAFOs with general permits (in essence, an NPDES permit adopted by a state that has general terms that apply to many CAFOs with similar manure management systems) must include an NMP for review and public comment when the CAFO elects to be covered by the general permit.

• CAFOs with Existing NPDES Permits

  CAFOs in some states, such as Iowa, were required to have NPDES permits in place before this final rule. These operations will not be required to comply with the new requirements in the final CAFO rule until their existing NPDES permits expire.

Consult Your Advisor

In summary, the requirements of the final CAFO rule are lengthy, detailed and will vary from state to state. This article is intended as a general overview only, and producers must work with their advisors to determine whether an NPDES permit is required for their operation or whether they should participate in the voluntary no-discharge certification option.