Diligence · Glossary
Phase I Environmental Site Assessment
Updated 2026-07-20
A Phase I ESA is a professional review of contamination risk history. Parcel View hazard layers are not a Phase I substitute.
What it means
A Phase I ESA is a professional review of contamination risk history. Parcel View hazard layers are not a Phase I substitute.
Why it matters for land decisions
Confirm how the concept applies to your specific parcel with the city or county planning department and the controlling agency map or ordinance.
- Treat online GIS as a first-pass screen.
- Verify before design, escrow, or lending decisions.
People also ask
What is Phase I Environmental Site Assessment?
A Phase I ESA is a professional review of contamination risk history. Parcel View hazard layers are not a Phase I substitute.
Is a GIS overlay enough to decide?
No. Public GIS is a screening tool. Official determinations come from the governing agency, recorded documents, and licensed professionals when required.
Official sources
Related terms
Check this on a California parcel
Parcel View screens zoning, flood, fire, soils, and planning layers for any California lot — every finding linked to the official source.