36 CFR 223.113: Modification of contracts to prevent environmental damage or to conform to forest plans.

Timber sale contract, permits, and other such instruments may be modified to prevent environmental damage or to make them consistent with amendments or revisions of land and resource management plans adopted subsequent to award or issuance of a timber sale contract, permit, or other such instrument. Compensation to the purchaser, if any, for modifications to a contract shall be made in accordance with provisions set forth in the timber sale contract. When determining compensation under a contract, timber payment rates shall be redetermined in accordance with appraisal methods in § 223.60 of this subpart.