Many sites, particularly the largest and most severely contaminated, are tracked at the national level, but many others are tracked only at state or local levels. No single comprehensive data source tracks the full extent of contaminated land in the United States.

In 2008, EPA expanded the scope of its national tracking efforts to include all the types of sites that fall under its purview, as well as estimates of the acreage attributed to those sites. The number and status of contaminated sites changes frequently as sites are newly contaminated (e.g., via spills or natural disasters such as hurricanes), discovered, documented, and cleaned up.

As of 2017, EPA and its partners reported overseeing approximately  640,000 to 1,319,100 facilities to prevent releases into communities.¹ Sites are categorized in a variety of ways, often based on the level and type of contamination and the regulations under which they are monitored and cleaned up.

Categories of Contaminated Lands

• Superfund National Priorities List sites: These sites are seriously contaminated and include industrial facilities, waste management sites, mining and sediment sites, and federal facilities such as abandoned mines; nuclear, biological, chemical, and traditional weapons production plants; and military base industrial sites (e.g., those used for aircraft and naval ship maintenance).
   
• Resource Conservation and Recovery Act (RCRA) cleanup facilities: These facilities are subject to cleanup under RCRA due to past or current treatment, storage, or disposal of hazardous wastes and have historical releases of contamination.
   
• Underground storage tanks/leaking underground storage tanks: Businesses, industrial operations, gas stations, and various institutions store petroleum and hazardous substances in large underground storage tanks that may fail due to faulty materials, installation, operating procedures, or maintenance systems, causing contamination of soil and ground water.
   
• Accidental spill sites: Each year, thousands of oil, gas, and chemical spills occur on land and in water from a variety of types of incidents, including transportation (e.g., rail, barges, tankers, pipelines) and facility releases.
   
• Sites contaminated by natural disasters or terrorist activities: Disasters of any sort, naturally occurring or caused by humans, have the potential to contaminate lands and cause problems at already-contaminated sites.
   
• Land contaminated with radioactive and other hazardous materials: Many sites spanning a large area of land in the United States are contaminated with radioactive and other hazardous materials as a result of activities associated with nuclear weapons production, testing, and research.
   
• Brownfields: Brownfields are real property where expansion, redevelopment, or reuse may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. Cleaning up and reinvesting in these properties protects the environment, reduces blight, and takes development pressures off green spaces and working lands.
   
• Military bases and defense sites: Some of the millions of acres of land used by the Department of Defense are contaminated from releases of hazardous substances and pollutants; discarded munitions, munitions constituents, and unexploded ordnance; and building demolition debris. Similarly, as part of its defense mission, the Department of Energy owns numerous facilities that have been contaminated from releases of hazardous chemical and/or radioactive substances.
   
• PCB-contaminated sites: Prior to the Toxic Substances Control Act, polychlorinated biphenyls (PCBs) were widely used across many commercial industries, and significant PCB contamination resulted from spills and releases, and from the use and disposal of products containing PCBs.
   
• Abandoned and inactive mine lands: Abandoned and inactive mines may not have been properly cleaned up, and may have features ranging from exploration holes to full-blown, large-scale mine openings, pits, waste dumps, and processing facilities.

Contaminated lands can pose a variety of health and environmental hazards. Some contaminated sites pose little risk to human health and the environment, because the level of contamination is low and the chance of exposure to toxic or hazardous contaminants is also low.

Other contaminated sites are of greater concern because of the chemicals that may be present and their propensity to persist in or move through the environment, exposing humans or the environment to hazards. These sites must be carefully managed through containment or cleanup to prevent hazardous materials from causing harm to humans, wildlife, or ecological systems, both on- and offsite.
 

• Contaminated soils can leach toxic chemicals into nearby ground or surface waters, where these materials can be taken up by plants and animals, contaminate a human drinking water supply, or volatilize and contaminate the indoor air in overlying buildings.
• In dry areas, contamination in soil can be further distributed through wind-borne dust. Once soil contamination migrates to waterways, it may also accumulate in sediments, which can be very difficult to remediate and may affect local ecosystems and human health.
• Humans can be harmed by contact with toxic and hazardous materials on a contaminated site via exposure to contaminated land, air, surface water, and ground water.
• When contaminated lands are not properly managed, humans and wildlife can be exposed to contaminants through inhalation, ingestion, or dermal contact. The risks of human exposure are site-specific and difficult to generalize at the national level. Potential effects may be acute or chronic.

The two ROE contaminated land indicators focus on Contaminated Ground Water Migration at Cleanup Sites and Human Exposures at Cleanup Sites.

These two indicators are limited in their ability to address the ROE contaminated lands question.

• Currently, no single information source tracks the extent of contaminated land nationwide. A substantial amount is known about the thousands of the high-priority (and generally highly contaminated) sites represented by the two indicators for this question, since these have been the focus of in-depth studies and resource-intensive cleanup operations. However, although these facilities are some of the most seriously contaminated sites in the country, they do not reflect the full universe of contaminated sites.
• Data gaps on contaminated lands stem from a variety of factors and challenges, including the multi-jurisdictional responsibilities for identifying, managing, and cleaning up contaminated lands.

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References

^[1]  U.S. Environmental Protection Agency. 2017. Office of Land and Emergency Management (OLEM) Accomplishments Reports and Benefits.

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