An Illinois-based company that operates an aluminum processing facility in The Dalles, pleaded guilty Wednesday to violating the Clean Air Act by negligently releasing a hazardous air pollution from its facility, endangering employees and those in the nearby community. Hydro Extrusion USA of Rosemont, Illinois, pleaded guilty to negligent endangerment by discharging a hazardous pollutant. Regulators said the company illegally melted contaminated scrap metal, forcing their workers and the local community to be exposed to hazardous air pollutants.