32 CFR 651.41 - Conditions requiring an EIS.
An EIS is required when a proponent, preparer, or approving authority determines that the proposed action has the potential to:
(a) Significantly affect environmental quality, or public health or safety.
(b) Significantly affect historic (listed or eligible for listing in the National Register of Historic Places, maintained by the National Park Service, Department of Interior), or cultural, archaeological, or scientific resources, public parks and recreation areas, wildlife refuge or wilderness areas, wild and scenic rivers, or aquifers.
(c) Significantly impact prime and unique farmlands located off-post, wetlands, floodplains, coastal zones, or ecologically important areas, or other areas of unique or critical environmental sensitivity.
(d) Result in significant or uncertain environmental effects, or unique or unknown environmental risks.
(e) Significantly affect a federally listed threatened or endangered plant or animal species, a federal candidate species, a species proposed for federal listing, or critical habitat.
(f) Either establish a precedent for future action or represent a decision in principle about a future consideration with significant environmental effects.
(g) Adversely interact with other actions with individually insignificant effects so that cumulatively significant environmental effects result.
(h) Involve the production, storage, transportation, use, treatment, and disposal of hazardous or toxic materials that may have significant environmental impact.
(i) Be highly controversial from an environmental standpoint.
(j) Cause loss or destruction of significant scientific, cultural, or historical resources.