About Site Plain
Methodology
- Site Plain uses EPA National Priorities List boundary polygons, not site centroids.
- Addresses are geocoded with the Census Geocoder first and Nominatim as fallback.
- Human exposure status comes from EPA's Human Exposure Site List JSON.
Limitations
- Proximity to a site boundary does not mean a property is contaminated.
- EPA site boundaries are not groundwater plume maps.
- The tool only covers active final NPL sites with boundary geometry.
Data Sources
- EPA NPL Superfund Site Boundaries
- EPA Human Exposure Site List JSON
- Census Geocoder and Nominatim
Data limitations: Proximity to a Superfund site boundary does not mean your property is contaminated. EPA site boundaries show the area designated for cleanup, not the full extent of contamination. Groundwater plumes can extend beyond site boundaries. This tool shows publicly available EPA federal data. It is not affiliated with or endorsed by EPA, and is not a substitute for a professional environmental assessment.