Legal Definitions - National Priorities List

National Priorities List (NPL)

The National Priorities List (NPL) is a public list maintained by the U.S. Environmental Protection Agency (EPA) that identifies the most severely contaminated hazardous waste sites across the United States. These sites pose significant risks to human health and the environment due to the presence of dangerous pollutants. Inclusion on the NPL makes a site eligible for extensive, long-term cleanup efforts funded by the federal Superfund program.

• Example 1: Abandoned Chemical Manufacturing Plant

  Imagine an old chemical manufacturing plant that closed down decades ago, leaving behind corroded drums of unknown substances and contaminated soil. Local residents have reported unusual odors and illnesses, and tests reveal that toxic chemicals have leached into the groundwater, threatening nearby drinking water wells. Because of the severe contamination and the direct threat to public health, the EPA would likely investigate this site and, if it meets the criteria, place it on the National Priorities List. This designation would then allow the site to receive federal funding and oversight for a comprehensive, multi-year cleanup under the Superfund program.

• Example 2: Former Mining Operation

  Consider a vast area in a mountainous region where mining operations ceased many years ago. The abandoned mine tailings (waste rock) contain high levels of heavy metals like lead and arsenic, which are now eroding into a nearby river, harming aquatic life and posing a risk to communities downstream that rely on the river for irrigation and recreation. The scale of contamination and the potential for widespread environmental damage and human exposure would make this site a strong candidate for the National Priorities List. Once listed, the EPA could initiate a large-scale remediation project to stabilize the tailings, prevent further runoff, and restore the affected ecosystem.

• Example 3: Contaminated Industrial Park

  Picture an industrial park where several different businesses operated over many years, including a dry cleaner, a metal plating facility, and an electronics manufacturer. Over time, spills and improper waste disposal practices led to a complex mix of chemicals, including solvents and heavy metals, saturating the soil and migrating into the underlying aquifer. While some businesses are still active, the historical contamination is extensive and poses a long-term risk to workers and the surrounding community. If the EPA determines that the collective contamination is severe enough and beyond the capacity of individual responsible parties to address effectively, it could designate the entire industrial park or a significant portion of it for the National Priorities List. This would enable a coordinated, federally-funded cleanup effort to address the widespread pollution.