NCEE Seminar: Chronic and Acute Water Contamination by Animal Feeding Operations: Evidence from Iowa and North Carolina

Contact: Ann Wolverton, 202-566-2278

Presenter:  Dr. Claire Palandri, University of Chicago

Description:  The immense majority of U.S. animal farming takes place in industrial Animal Feeding Operations (AFOs), where large quantities of manure are produced, stored, then typically spread onto fields. The concentration of animal waste is thought to threaten environmental and public health, as airborne and waterborne transmission puts communities at risk of environmental exposure to its contaminants. Water pollution from swine operations is of particular concern, yet there are no robust causal estimates of this externality to date.

I gather panel data of all permitted AFOs in the two main hog producing states — Iowa (2002-2017) and North Carolina (1997-2020) — and estimate the effects of animal production on downstream surface water quality readings. My analysis espouses the spatial structure of the underlying process by constructing station-specific drainage areas, and we use two identification strategies appropriate for the states’ regulatory settings and data resolution: the first leverages the spatio-temporal variation in animal production in Iowa, the second the randomness of intense precipitation events on North Carolina farms.

I find deleterious effects across water quality indicators and across types of operations, including from facilities below the size threshold at which the industry is currently regulated. A daily rainfall extreme at an AFO increases downstream levels of fecal coliforms by 3.5%, and nutrients by 0.5-0.7%, relative to mean sample levels, while an additional swine operation in the average station drainage area increases nutrient concentrations by 3.8-10.7% and decreases dissolved oxygen by 1.1%, relative to sample mean levels. These effects are higher than previous findings focused on large dairies, and are higher for swine AFOs relative to all AFOs.

Note: Hosting these seminars does not necessarily express or imply EPA approval or endorsement of the speaker’s views.

Additional information:

This seminar is open to EPA staff and interested parties outside EPA.

For more information on the NCEE environmental economics seminar series, contact

Dr. Ann Wolverton
U.S. Environmental Protection Agency (1809T)
1200 Pennsylvania Ave., NW
Washington, D.C. 20460

TEL.:  202-566-2278
E-MAIL:  WOLVERTON.ANN@EPA.GOV

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