(a) Except as provided in paragraphs (c) and (f) of this section, the final array of alternatives shall include, at a minimum, the following six alternatives:

(1) A No Action alternative.

(2) A nonstructural alternative: An alternative that can effectively address the problem through the feasible use of nonstructural approaches.

(3) A nature-based solution alternative: An alternative that can effectively address the problem through the feasible use of nature-based solutions (including natural systems and ecosystem processes).

(4) An environmentally preferred alternative.

(5) An alternative that seeks to maximize net public benefits to society. In developing this alternative, the Corps shall not consider regional economic development effects.

(6) An alternative that is locally preferred. If this alternative differs from the net public benefits alternative, it will be required to have a comparable level of detail and analyzed using the same analytical framework as the net public benefits alternative.

(b) The nonstructural and nature-based alternatives do not preclude consideration of these elements in other alternatives. Nonstructural measures and nature-based solutions shall be considered as components of the other alternatives in the final array, essentially providing an integrated or “hybrid” of gray (hard) infrastructure with these other measures.

(c) The same alternative may be identified as more than one of these required alternatives.

(d) Mitigation of unavoidable adverse effects associated with each alternative must be included in the alternative and in the analyses.

(e) If an alternative requires changes in existing laws, regulations, or policies, those changes must be clearly identified and explained.

(f) If one or more of the required alternatives is not included because the Corps was not able to identify a potential solution that is feasible and consistent with the purpose of the study, the study must document that decision.

(g) The discussion of the final array of alternatives should include the primary purpose of the analysis; the geographic size of the study area; the types of impacts; the number of people potentially affected and anticipated degree of impact; environmental justice considerations; the size and location of communities potentially affected including the presence of Federally-recognized Tribes or Tribal members; and the type of data and information available from Indigenous Knowledge, collaboration, public involvement, and previous studies.