Size-based regulation and water quality: Evidence from the Iowa hog industry
Date
2025-07-24
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Wiley Periodicals LLC on behalf of Agricultural & Applied Economics Association
Abstract
The growing prevalence of animal feeding operations (AFOs) in the United States raises concerns among the public and regulators about their impact on local environmental quality. By linking historical regulatory records of AFOs in Iowa to downstream surface water pollution monitors, this paper studies the effects of the 2003 Clean Water Act regulations that targeted water pollution from the largest hog AFOs. The regulation decreased ammonia concentrations downstream of large hog AFOs by 6–8 percentage points. We find limited to no evidence of improvement for dissolved oxygen and phosphorus concentrations. Pollution reductions are largest during heavy precipitation months, consistent with the regulations reducing on-site spills and nutrient runoff from local fields. However, we find that pollution increased downstream from mid-sized hog AFOs, which were exempt from the updated regulations. Given the growth in the number of mid-sized facilities relative to large AFOs, we estimate that the regulation had little discernible impact on overall water quality.
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Sized-based Regulation and Environmental Quality: Evidence from the US Livestock Industry
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2024-01)
The growing prevalence of animal feeding operations (AFOs) in the United States raises concerns among the public and regulators about their impact on local environmental quality. This paper studies the effects of Clean Water Act regulations that targeted water pollution from the largest hog AFOs. We compile a novel dataset linking historical regulatory records of AFOs in Iowa to downstream surface water pollution monitors. The regulation decreased ammonia concentrations downstream of large AFOs by 6 to 9 percentage points and modestly improved dissolved oxygen concentrations, but did not reduce phosphorus concentrations. Pollution reductions are largest during heavy precipitation months, consistent with the regulations reducing on-site spills and nutrient runoff from local fields. However, we find that pollution increased downstream from mid-sized AFOs, which were exempt from the regulations. Given the growth in the number of mid-sized facilities relative to large AFOs, we estimate that the regulation had little discernible impact on overall water quality.
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article
Comments
JEL Classification: Q15, Q18, Q53, Q58
This article is published as Chen, Chen‐Ti, Gabriel E. Lade, John M. Crespi, and David A. Keiser. "Size‐based regulation and water quality: Evidence from the Iowa hog industry." American Journal of Agricultural Economics (2025). doi:https://doi.org/10.1111/ajae.70006
This article is published as Chen, Chen‐Ti, Gabriel E. Lade, John M. Crespi, and David A. Keiser. "Size‐based regulation and water quality: Evidence from the Iowa hog industry." American Journal of Agricultural Economics (2025). doi:https://doi.org/10.1111/ajae.70006
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© 2025 The Author(s). This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.