Claire Palandri (University of Chicago)
Over the past century, U.S. livestock production has shifted from many small farms to fewer, increasingly larger operations. Today, most animals are raised in confined Animal Feeding Operations (AFOs), where manure is stored on-site and eventually applied to fields. This concentration of waste has long raised concerns about pollution, yet credible causal evidence on its impacts remains scarce. I assemble new panel data linking AFOs in Iowa and North Carolina to downstream water monitoring records and delineate station-specific drainage basins to capture the hydrological structure of pollutant transport. The analysis exploits two complementary research designs. In both states, I implement an event-study approach leveraging extreme precipitation shocks at the location of the operations. In Iowa, I additionally implement a difference-in-differences design exploiting spatio-temporal variation in the intensity of upstream livestock production. Across both settings, I find that AFO activity significantly degrades surface water quality, with substantial increases in downstream fecal bacteria and nutrient concentrations following increases in animal production and extreme rainfall events. Pollution scales with herd size, worsens with spatial concentration for a given livestock burden, and arises from facilities below regulatory thresholds, highlighting the limits of the current regulatory framework. With global livestock production projected to grow and intensify further, and with regulatory changes in some regions moving toward weaker environmental oversight, these findings provide timely evidence on the pollution risks of large-scale operations.