The National Priorities List, or NPL, is a list compiled by the Environmental Protection Agency (EPA) as a part of the Superfund program under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). CERCLA was enacted by Congress on December 11, 1980. This law levied a tax on the chemical and petroleum industries and gave the Federal government broad authority to respond directly to actual or threatened releases of hazardous substances. $1.6 billion was collected in the five years between 1980 and 1985. The tax money was placed in a trust fund for cleaning up abandoned or uncontrolled hazardous waste sites. CERCLA was amended by the Superfund Amendments and Reauthorization Act (SARA) on October 17, 1986.

CERCLA requires the EPA to identify hazardous waste sites on an annual basis throughout the United States. The law allows for two types of response: short-term removal of hazardous materials in emergency situations; and long-term...