Pending manure rule poses murky math problem

Producers are in a “totally confusing situation” calculating whether their livestock emit enough ammonia to qualify as a source of hazardous gas under a new federal rule, a leading authority on estimating manure emissions said Thursday.

University of Nebraska professor Rick Stowell said guidance offered by the Environmental Protection Agency, based largely on research by Stowell and a colleague, has been vague.

“It’d sure be nice to have clarity on this. It’s not going to be easy for producers to decide whether to report and what to report, and that’s an unfortunate situation,” Stowell said.

Animal feeding operations that emit more than 100 pounds of ammonia or hydrogen sulfide in 24 hours will have to register annually beginning early next year with the National Response Center. The center, staffed by the U.S. Coast Guard, coordinates federal emergency responses to chemical leaks.

The EPA had sought to exempt agriculture from having to report. The agency said it was unlikely decaying manure would ever need an emergency response. Environmental groups sued, however. The D.C. Circuit Court of Appeals agreed that knowing where manure was could be useful to emergency responders.

The court is expected to finalize its order Jan. 22. The court has yet to clarify whether farms also will have to report to local and state officials.

The EPA estimates that 44,900 farms will spend $14.9 million a year to register with the National Response Center. It has not estimated how many cows, pigs or chickens it takes to exceed the reporting threshold.

Instead, an EPA website links to a worksheet finalized in 2009 by Stowell and another University of Nebraska professor, Rick Koelsch. Washington State University animal scientist Joe Harrison, who works with the dairy industry, said the Stowell-Koelsch worksheet is the best science available on calculating ammonia, the gas more likely to reach the threshold.

Nevertheless, Stowell said the worksheet only “crudely estimates emissions.” Emissions are affected by factors such as climate, the seasons, animal housing and manure storage.

Stowell said that his and Koelsch’s worksheet should apply to many regions, though producers who use an emissions calculator developed in Texas probably will come up with much different numbers.

“Mirror-image dairies across the road from each other … can easily come up with different, yet acceptable, estimates,” he said. “This introduces a lot of confusion to an already confounding decision.”

Koelsch said in an email that although using the worksheet to estimate emissions appears acceptable to the EPA, he advises producers to check with their commodity commissions or trade associations.

EPA says that because there is no generally accepted methodology for estimating emissions, farmers may need to report their emissions in broad ranges. As of Friday afternoon, EPA had not issued further guidance.

In the absence of such guidance, Stowell said he’s been reluctant to say how many barnyard animals it takes to give off at least 100 pounds of ammonia in 24 hours.

“Those sizes are not specified by the EPA, so as soon as we start throwing out those numbers, it’s like we’re making the rules, and I don’t want to do that,” he said.

The Waterkeeper Alliance, Sierra Club, Humane Society of the United States, the Environmental Integrity Project and Center for Food Safety brought the lawsuit to force agriculture to report the emissions under the Comprehensive Environmental Response, Compensation and Liability Act, commonly known as Superfund.


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