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.
Distance results only cover active final NPL sites with an EPA-published boundary. Active sites without one have a site page but no distance.

Data sources

EPA NPL Superfund Site Boundariesloaded October 11, 2026
EPA Superfund Human Exposure listloaded November 11, 2026
U.S. Census Geocoder Finds each address; queried at lookup time
OpenStreetMap Nominatim Fallback when the Census Geocoder finds no match

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.