(1) The agency shall prepare supplements to
either draft or final environmental impact statements whenever:
(a) the agency or the applicant makes a substantial
change in a proposed action;
(b) there are significant new circumstances,
discovered prior to final agency decision, including information bearing on the
proposed action or its impacts that change the basis for the decision; or
(c) following preparation of a draft EIS and prior
to completion of a final EIS, the agency determines that there is a need for
substantial, additional information to evaluate the impacts of a proposed
action or reasonable alternatives.
(2) A supplement must include, but is not limited
to, a description of the following:
(a) an explanation of the need for the supplement;
(b) the proposed action; and
(c) any impacts, alternatives of other items
required by ARM 32.2.229 for a draft EIS or ARM 32.2.231 for a final EIS that
were either not covered in the original statement or that must be revised based
on new information or circumstances concerning the proposed action.
(3) The same time periods applicable to draft and
final EISs apply to the circulation and review of supplements.