Conference Agenda

Agricultural and other nonpoint sources have typically been exempted from the permitting requirements of the National Pollutant Discharge Elimination System (NPDES), including the system monitoring and enforcement requirements. However, EPA recently updated the program to require permits for animal feeding operations (AFO) that potentially contribute to surface waterbody impairments. This study contributes to the literatures on (1) the effectiveness of monitoring and enforcement, i.e., regulatory interventions, and (2) the water quality impacts of AFOs, by examining the efficacy of NPDES inspections and enforcement actions administered against permitted AFOs in the US. Unlike standard point sources, permitted AFOs do not face numeric discharge limits and contribute to surface waterbody pollution through nonpoint source runoff rather than direct discharges. Given this pollution pathway, we examine the efficacy of regulatory interventions at improving the environmental (manure) management of AFOs by analyzing the interventions’ impacts on surface water quality. Despite the importance of AFOs, no previous study of regulatory interventions examines this type of discharge source. Our analysis leverages within-AFO variation in experiences with regulatory interventions and the upstream and downstream nature of the US water network to identify the effects of interventions on total phosphorus and total nitrogen concentrations. We find that the more “severe” actions – federal inspections and monetary penalties – (compared to state inspections and informal enforcement) reduce downstream concentrations of total phosphorus and total nitrogen by between 1 % and 3 %. We provide a benefit-cost analysis that suggests regulatory interventions at AFOs produce water quality benefits that largely exceed the associated costs.