What is an environmental impact statement (EIS), and when is one required?
If no significant effect is reasonably foreseeable, or its significance is unknown, the agency prepares an environmental assessment instead, unless a categorical exclusion applies[2].
Recent filings show the range: EPA's September 25, 2026 notice lists EISs for a TVA solar and storage project, Air Force F-35A training basing and a FERC liquefaction project[8]. Some agencies list actions that normally need one; FHWA, FRA and FTA name these, among others[9]:
- A new controlled-access freeway
- A highway of four or more lanes on a new location
- A new or extended fixed transit facility, such as light rail, not primarily within existing transportation right-of-way
- A new major railroad line or facility outside existing transportation right-of-way
EIS steps: notice of intent, draft and final EIS, record of decision
With CEQ's regulations at 40 CFR parts 1500-1508 removed in 2025[10], the statute and each agency's NEPA procedures set the steps[11]. The usual sequence:
- Notice of intent: a Federal Register notice that must request comment on alternatives, impacts and relevant information[12][6]
- Scoping: optional under USDA; FHWA, FRA and FTA scope before the NOI[12][13]
- Draft EIS: agency procedures decide whether it circulates; EPA recommends 45 days of comment[5][7]
- EPA review: EPA comments on every draft EIS under Clean Air Act section 309 and posts its letters[14]
- Final EIS: responds to comments and, under FHWA's rule, names the preferred alternative; EPA recommends 30 days' review[15][7]
- Record of decision: states the selected alternative and mitigation; FHWA combines it with the final EIS where practicable[4][16]
How long does an EIS take? Page limits and the two-year deadline
The median EIS took 2.2 years from notice of intent to final EIS in 2024, and 2.5 years to the record of decision in 2021 to 2024[17].
USDA and DOE count 8.5 by 11 inch pages of single-spaced 12-point text, including pages of maps and tables[12][5]. The lead agency may extend the deadline, in consultation with the applicant, only as long as needed, and a project sponsor may petition a court over a missed deadline[6]. FHWA stops the clock at the signed record of decision[18]; DOE at EPA's notice of availability[5].
Supplemental EIS and programmatic EIS
FHWA, FRA and FTA supplement an EIS when changes to the action, or new information or circumstances, would cause significant impacts it did not evaluate[19]. DOE writes a supplement analysis when it is unclear whether one is needed[5].
A programmatic EIS analyzes the effects of a policy, program, plan or group of related actions[1]. Where judicial review of it was available, later reviews of related actions may rely on it for five years unless substantial new circumstances or information bear on it, and after that if the agency reevaluates it[20].