A comment period deadline is approaching on a potential U.S. Environmental Protection Agency (EPA) rule covering animal waste air emission reporting requirements. EPA is accepting comments until Feb. 15.

Natzke dave
Editor / Progressive Dairy

The step is another in a multidecade legal and administrative battle over manure air emission reporting requirements under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), created in 1980, and the Emergency Planning and Community Right-to-Know Act (EPCRA), created in 1986. The laws required entities to report the release of hazardous materials into the environment to federal (under CERCLA) and state or local (under EPCRA) agencies.

Two substances included under the reporting requirements – ammonia and hydrogen sulfide – are emitted during decomposition of livestock manure.

Reporting requirement exemptions for livestock operations have been approved and rescinded multiple times, with the latest exemption granted in 2019. However, after another lawsuit filed by environmental groups opposed that exemption, EPA reopened consideration of the rule in 2023.

Regarding regulation development, the ability to monitor livestock manure air emissions has long been questioned. In 2022, EPA published preliminary draft air emission models for dairy operations, developed using data gathered during the National Air Emissions Monitoring Study (NAEMS).


The preliminary draft models estimate daily and annual air emissions of ammonia, hydrogen sulfide and particulate matter from barns and manure lagoons on dairy farms. The methodologies include type and number of animals, animal weights, housing type, waste management methods and ambient relative humidity, ambient temperature and wind speed. 

For background and a historical timeline on the reporting requirements, visit the Penn State Law Center for Agricultural and Shale Law website and the EPA rule-making website. To submit comments, visit the Federal Register.