Sites in ECSI comprise a wide variety of sizes, locations, features, contaminant profiles, and degrees of Cleanup Program information. What all sites have in common is documented, suspected, or remediated hazardous substance contamination in groundwater, surface water, soil, or sediments. Some ECSI sites have minimal information available and need an initial evaluation, while others have completed investigative and remedial actions, and have earned a NFA decision from DEQ. Sites range from urban industrial complexes to isolated rural facilities contaminated by disposals or spills. Most sites are either industrial or commercial, but the Cleanup Program sometimes adds highly contaminated residential properties to ECSI.
ECSI also includes study areas, which are groups of individual sites that may be contributing to a larger, area-wide problem. For example, when DEQ discovers regional groundwater contamination where the sources of contamination are not known, it will create a study area for this region. Then, DEQ will add sites within the region’s boundaries to this study area, and these sites may be investigated to determine if they’re potential sources of contamination. DEQ has also created study areas of sites that could threaten Vulnerable Areas such as drinking water sources or streams with endangered fish species.