In a March 15, 2011, decision, the Fifth Circuit Court of Appeals vacated in part the Environmental Proection Agency’s (“EPA”) Concentrated Animal Feeding Operations (“CAFO”) rules, which we analyzed in a previous blog entry. The Fifth Circuit struck down the requirement that CAFOs which “propose to discharge”—that is, which are “designed, constructed, operated, or maintained such that a discharge would occur”—must obtain NPDES permits. Under EPA’s “propose to discharge” standard, a CAFO could be required to obtain an NPDES permit even if it had never discharged. Similarly, under the now-vacated standard, if a CAFO which had not obtained a permit actually discharged, it may have then faced an enforcement action not only for the illegal discharge but also for failing to obtain a permit. The Fifth Circuit rejected this “propose to discharge” standard and found instead that facilities which merely propose to discharge without actually discharging need not obtain NPDES permits. EPA had promulgated the “propose to discharge” standard in 2008 following a 2005 Second Circuit decision which had struck down a previous “potential to discharge” standard under which EPA sought to require facilities to obtain NPDES permits unless they could show they had no potential whatsoever to discharge. This ruling could impact the interest of companies in considering waste-to energy projects sparked by EPA’s CAFO rules.