33 C.F.R. § 333.12
(a) If the District Engineer determines under § 333.11 that NEPA applies to a proposed activity or decision, the District Engineer will then determine the appropriate level of NEPA review in the following sequence and manner. At all steps in the following process, the Corps will consider the proposed activity and its effects.
(4) If the District Engineer cannot apply a categorical exclusion to the proposed activity consistent with paragraphs (a)(1)-(3), the District Engineer will determine the appropriate level of review, i.e., whether the proposed activity warrants preparation of an environmental assessment or an environmental impact statement. Most activities requiring a Corps permit that are not otherwise covered by a categorical exclusion normally require only an environmental assessment. In determining the level of review, the District Engineer will consider the proposed action's reasonably foreseeable effects consistent with paragraph (b), and then will:
(b) When considering whether the reasonably foreseeable effects of the proposed activity are significant, the District Engineer will analyze the potentially affected environment and degree of the effects of the activity within their jurisdiction or control. The District Engineer may use any reliable data source, but will not undertake new research of any type unless it is essential to evaluating alternatives and the cost and time of obtaining it are not unreasonable. District Engineers should not determine that a proposed activity is significant based solely on public interest or opposition.
(2) In considering the degree of the effects, the District Engineer may consider the following, as appropriate to the specific action: