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Environmental Impact Statement (EIS) Process and Environmental Assessment (EA) Process

  EA NEPA process flow chart - thumb nail
NEPA Process Flow Chart -- click image to enlarge.

An Environmental Impact Statement (EIS) is required for actions that are likely to have a significant impact the natural or built environment. The EIS describes extent and level of long and short-term environmental impacts, project benefits and mitigation measures.  Completion of an EIS requires an open public process proscribed by State and Federal Law.

An Environmental Assessment (EA) is prepared when the impact of a proposed project on the environment is not clearly understood.  The EA describes the extent and level of environmental impact.  The document will either support a Finding of No Significance (FONSI) or indicate that an EIS is warranted.

The information on this page is designed for a technical audience.

Chapter 400 of the Environmental Manual (EM) describes policies that must be considered when completing an EIS or an EA.


Document Impacts

  • Preparing an EIS (pdf 117 kb) PRO 400-b provides a step-by-step procedure from project assignment to issuance of the ROD.
  • Preparing an EA (pdf 528 kb) PRO 400-a provides a step-by-step procedure from project assignment to issuance of the FONSI.
  • Refer to the NEPA/SEPA Support web page for Discipline Report guidance, checklists and templates. 
  • FHWA Technical Advisory TA6640.8a Section V includes the cover sheet, outline, and description of recommended content.

Document Review and Inviting Comments 

Re-evaluations and Supplemental Documents

Adopting NEPA Documents Under SEPA Rules

As a matter of practice, Project Teams should complete the NEPA and SEPA environmental review process simultaneously in a single document.  When a NEPA document is completed without considering SEPA, that NEPA EA/EIS can be adopted using the form found in WAC 197-11-965 .  The form/determination notice is signed according to agency SEPA delegations:  the ESO Director signs an EIS/EA, the Region/Mode Environmental Manager signs a DNS.

Document Basics


EA/EIS Resources

  • FHWA's FAST Act webpage provides guidance, presentations, and fact sheets regarding the new transportation bill. (Feb 2016)
  • Congress passed the "Fixing America's Surface Transportation (FAST) Act" on 12/4/15. The act provides $300 billion dollars over 5 years for highway, transit, highway safety, and rail projects.
  • eNEPA - Project Management -- An Introduction to FHWA eNEPA and link to this optional tool for collaboration on EA/EIS level projects.
  • NEPA/SEPA Sample Documents Library contains example documents.  This database can be accessed from the WSDOT intranet Environment page and is only available to WSDOT employees.
  • WSDOT Limited English Proficiency web page.