Can information in existing environmental documents be used for a new or amended proposal?
Yes, there are several ways that information in existing documents can be used: 1) adoption, 2) incorporation by reference, 3) addendum, or 4) supplemental EIS. Using existing information reduces duplication and delays caused by conducting duplicate studies and analysis. A new threshold determination is required for a new proposal, except those qualifying as planned actions. Agencies may adopt all or part of existing documents to support a new threshold determination, or the information may be “incorporated by reference.” A revised proposal generally does not require a new threshold determination, so adoption of the original document would not be required for the revised proposal. An addendum may be used for either a new or revised proposal, if the analysis in the existing document (DNS or EIS) addresses all likely significant adverse impacts. The addendum would explain the differences between the original and the current proposal, and other minor new information. For a new proposal, t
