A GIS and Literature Review Study of CAFO Surface Water Pollution in North Carolina

Abstract

Concentrated animal feeding operations (CAFOs) are large-scale livestock facilities where animals are confined and fed for extended periods, typically more than 45 days per year, and where waste is managed in concentrated systems rather than dispersed across pastureland. This project integrates a comprehensive literature review, evaluation of existing regulatory frameworks, analysis of siting restrictions and mitigation technologies, and a geospatial assessment to examine the cumulative impacts of CAFOs across the state. Evidence from prior research consistently shows that lagoon-and-spray field waste systems contribute nitrogen, phosphorus, ammonia, dissolved organic carbon, and fecal indicator bacteria to adjacent surface water and groundwater. These contaminants move through multiple pathways, including spray field runoff, soil leaching, storm-related overflow, and hydrologically connected floodplains. Long-term monitoring studies demonstrate that nutrient concentrations can rise in wells, trenches, and streams near CAFOs even when direct lagoon leakage is not detected, suggesting broader landscape-scale transport mechanisms. At the same time, emerging mitigation technologies show promising performance. Modified bioretention systems with biochar amendments and internal water storage zones achieve high removal efficiencies for nitrogen and fecal bacteria, while advanced treatment systems developed to meet Environmentally Superior Technology standards demonstrate substantial reductions in odors, pathogens, nutrients, ammonia emissions, and heavy metals. Despite their effectiveness, widespread adoption of these technologies remains limited due to cost barriers and lack of regulatory requirements. The geospatial analysis conducted for this project identified 2,479 registered animal feeding operations in North Carolina, with 371 located within 1 km of a surface water body and 1,170 within 3 km. High-density CAFO clusters in Duplin, Sampson, Wayne, Bladen, and Greene Counties overlap extensively with impaired waterways, vulnerable floodplains, and communities already experiencing environmental and socioeconomic stress. Overall, this project demonstrates that current CAFO siting, waste management, and regulatory practices do not adequately protect water resources or public health in North Carolina.