(a) The Commission shall determine whether any Commission proposal:

(1) Is categorically excluded from preparation of either an EA or an EIS;

(2) Requires preparation of an EA; or

(3) Requires preparation of an EIS.

(b) Notwithstanding any other provision of this part, the Commission may prepare a NEPA document to assist any Commission action at any time in order to further the purposes of NEPA. This NEPA document may be done to analyze the consequences of ongoing Commission activities, to support Commission planning, to assess the need for mitigation, to disclose fully the potential environmental consequences of Commission actions, or for any other reason. Documents prepared under this paragraph shall be prepared in the same manner as Commission documents prepared under this part.