As of May 1999, the database contained records for 10,625 active sites.
Specific information is maintained for each site.
The database contains records for active Superfund sites, the number of which changes over time. Each site can contain multiple operable units, or distinct portions of the site where assessment, cleanup, enforcement, and planning and tracking activities occur. As a management database, many entries include date fields, allowing for temporal analysis. There is some consistency from site to site with regard to spatial and temporal characteristics. Data entered at the time of site discovery are preserved on Site Discovery screens to reflect the information originally entered for the site.