On August 28, 2009, the U.S. Environmental Protection Agency (U.S. EPA) published a proposed rule that would establish new technology-based effluent limitation guidelines (ELGs) and new source performance standards (NSPS) under the Clean Water Act for discharges from airport deicing operations. Airport operators are currently required to obtain stormwater discharge permits under the National Pollutant Discharge Elimination System (NPDES) program and to ensure that wastes from deicing operations are properly collected and treated. The EPA’s proposed rule would be implemented through the NPDES permit program. The proposed rule would generally apply to wastewater associated with the deicing of aircraft and airfield pavement at primary commercial airports. Airports that conduct aircraft deicing operations, have 1,000 or more annual jet departures, and 10,000 or more total annual departures, would be required to collect spent aircraft deicing fluid and treat the wastewater. They may either treat the wastewater on-site or send it to an off-site treatment contractor or publicly-owned treatment works. Some airports would be required to reduce the amount of ammonia discharged from urea-based airfield pavement deicers or use airfield deicers that do not contain urea. Comments on the proposed rule must be filed by December 28, 2009.