40 CFR § 1501.1 - NEPA thresholds.
(a) In assessing whether NEPA applies or is otherwise fulfilled, Federal agencies should determine:
(1) Whether the proposed activity or decision is expressly exempt from NEPA under another statute;
(2) Whether compliance with NEPA would clearly and fundamentally conflict with the requirements of another statute;
(3) Whether compliance with NEPA would be inconsistent with Congressional intent expressed in another statute;
(4) Whether the proposed activity or decision is a major Federal action;
(5) Whether the proposed activity or decision, in whole or in part, is a non-discretionary action for which the agency lacks authority to consider environmental effects as part of its decision-making process; and
(6) Whether the proposed action is an action for which another statute's requirements serve the function of agency compliance with the Act.
(b) Federal agencies may make determinations under this section in their agency NEPA procedures (§ 1507.3(d) of this chapter) or on an individual basis, as appropriate.
(1) Federal agencies may seek the Council's assistance in making an individual determination under this section.
(2) An agency shall consult with other Federal agencies concerning their concurrence in statutory determinations made under this section where more than one Federal agency administers the statute.