(a) Applicability. As a threshold determination, an agency shall assess whether NEPA applies to the proposed activity or decision. In assessing whether NEPA applies, Federal agencies should determine:

(1) Whether the proposed activity or decision is exempted from NEPA by law;

(2) Whether compliance with NEPA would clearly and fundamentally conflict with the requirements of another provision of Federal law;

(3) Whether the proposed activity or decision is not a major Federal action (§ 1508.1(w) of this subchapter);

(4) Whether the proposed activity or decision is not a final agency action within the meaning of such term in chapter 5 of title 5, United States Code; or

(5) Whether the proposed activity or decision is a non-discretionary action with respect to which such agency does not have authority to take environmental factors into consideration in determining whether to take the proposed action.

(b) Scope of action and analysis. If the agency determines that NEPA applies, the agency shall consider the scope of the proposed action and its effects to inform the agency's determination of the appropriate level of NEPA review and whether aspects of the action are non-discretionary. The agency shall use, as appropriate, the public engagement and scoping mechanisms in §§ 1501.9 and 1502.4 of this subchapter to inform consideration of the scope of the proposed action and determination of the level of NEPA review. The agency shall evaluate, in a single review, proposals or parts of proposals that are related closely enough to be, in effect, a single course of action. The agency shall not avoid a determination of significance under paragraph (c) of this section by terming an action temporary that is not temporary in fact or segmenting an action into smaller component parts. The agency also shall consider whether there are connected actions, which are closely related Federal activities or decisions that should be considered in the same NEPA review that:

(1) Automatically trigger other actions that may require NEPA review;

(2) Cannot or will not proceed unless other actions are taken previously or simultaneously; or

(3) Are interdependent parts of a larger action and depend on the larger action for their justification.

(c) Levels of NEPA review. In assessing the appropriate level of NEPA review, agencies may make use of any reliable data source and are not required to undertake new scientific or technical research unless it is essential to a reasoned choice among alternatives, and the overall costs and timeframe of obtaining it are not unreasonable. Agencies should determine whether the proposed action:

(1) Is appropriately categorically excluded (§ 1501.4);

(2) Is not likely to have significant effects or the significance of the effects is unknown and is therefore appropriate for an environmental assessment (§ 1501.5); or

(3) Is likely to have significant effects and is therefore appropriate for an environmental impact statement (part 1502 of this subchapter).

(d) Significance determination—context and intensity. In considering whether an adverse effect of the proposed action is significant, agencies shall examine both the context of the action and the intensity of the effect. In assessing context and intensity, agencies should consider the duration of the effect. Agencies may also consider the extent to which an effect is adverse at some points in time and beneficial in others (for example, in assessing the significance of a habitat restoration action's effect on a species, an agency may consider both any short-term harm to the species during implementation of the action and any benefit to the same species once the action is complete). However, agencies shall not offset an action's adverse effects with other beneficial effects to determine significance (for example, an agency may not offset an action's adverse effect on one species with its beneficial effect on another species).

(1) Agencies shall analyze the significance of an action in several contexts. Agencies should consider the characteristics of the geographic area, such as proximity to unique or sensitive resources or communities with environmental justice concerns. Depending on the scope of the action, agencies should consider the potential global, national, regional, and local contexts as well as the duration, including short-and long-term effects.

(2) Agencies shall analyze the intensity of effects considering the following factors, as applicable to the proposed action and in relationship to one another:

(i) The degree to which the action may adversely affect public health and safety.

(ii) The degree to which the action may adversely affect unique characteristics of the geographic area such as historic or cultural resources, parks, Tribal sacred sites, prime farmlands, wetlands, wild and scenic rivers, or ecologically critical areas.

(iii) Whether the action may violate relevant Federal, State, Tribal, or local laws or other requirements or be inconsistent with Federal, State, Tribal, or local policies designed for the protection of the environment.

(iv) The degree to which the potential effects on the human environment are highly uncertain.

(v) The degree to which the action may adversely affect resources listed or eligible for listing in the National Register of Historic Places.

(vi) The degree to which the action may adversely affect an endangered or threatened species or its habitat, including habitat that has been determined to be critical under the Endangered Species Act of 1973.

(vii) The degree to which the action may adversely affect communities with environmental justice concerns.

(viii) The degree to which the action may adversely affect rights of Tribal Nations that have been reserved through treaties, statutes, or Executive Orders.