CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) sites, more commonly known as "Superfund" sites, are hazardous waste sites on the US Environmental Protection Agency's National Priorities List for cleanup. Over 80% of Superfund sites have ground water that is contaminated to some degree. Although the Superfund program works to restore contaminated ground water at these sites, or prevent it from moving to uncontaminated areas, the existing contamination at these sites has the potential to impact drinking water sources.