State/Tribal Superfund-Equivalent Sites (SHWS)

Each state maintains its own inventory of known or suspected hazardous substance release sites addressed under state cleanup authority, the state analog to the federal NPL/SEMS pipeline. Vendors label these SHWS (State Hazardous Waste Sites) or by the state program's own name. The state list is usually far longer than the federal one, because most cleanup work in the U.S. happens under state programs.

In a Phase I ESA

ASTM E1527-21 requires a 1.0 mile search, the same distance as the federal NPL, reflecting that these are documented or suspected release sites. Sites that have dropped off the list matter as much as current ones (Table 2, Note A).

The listing detail carries the analysis: site status (active investigation, remediation, closed, closed with controls), contaminants, and media affected. A closed state site with a groundwater use restriction adjoining the subject property is a very different fact from an open investigation two-thirds of a mile cross-gradient.

Where the data lives

The state environmental agency's cleanup program database. Naming and structure vary by state. The agency's online site lookup is usually the authoritative record, and the state file is the one to pull when the subject or an adjoining property is listed.