(a) Either the State Office or the National Office, as appropriate, will prepare supplements to either draft or final EIS's if:
(1) A substantial change or changes occur in the proposed action and such changes are relevant to the environmental impacts previously presented; and
(2) Significant new circumstances or information arise which are relevant to environmental concerns and bear on the proposed action or its impacts.
(b) If the preparer of the draft or final EIS determines that the changes or new circumstances referenced in paragraph (a) of this section do not require the preparation of a supplemental EIS, the preparer will complete an environmental assessment for a Class II action which will document the reasons for this determination.
(c) The preparer will be responsible for advising the approving official of the need for a supplement. The latter will make the Agency's formal determination in a manner consistent with Sec. 1940.316 of this subpart.
(d) All of the requirements of this subpart that apply to the completion of an initial EIS apply to the completion of a supplement with the exception of the scoping process, which is optional. Additionally, if the approving official believes that there is a need for expedited or special procedures in the completion of a supplement, the approval of CEQ must first be obtained by the Administrator for any alternative procedures. The final supplement will be included in the project file or docket and used in the Agency's decisionmaking process in the same manner as a final EIS. (See Sec. 1940.321 of this subpart and in particular subparagraphs (f), (g), and (j) of that section as well as Sec. 1502.9(c)(4) of the CEQ regulations for associated circulation, filing, and timing requirements.)