7 CFR § 799.56 - Supplemental EIS.
(a) FSA will prepare supplements to a draft or final EIS if:
(1) Substantial changes occur in the proposed action that are relevant to environmental concerns; or
(2) Significant new circumstances or information arise that are relevant to environmental concerns and bearing on the proposed action or its impacts.
(b) The requirements of this subpart for completing the original EIS apply to the supplemental EIS, with the exception of the scoping process, which is optional.