40 CFR § 1503.4 - Response to comments.
(a) An agency preparing a final environmental impact statement shall consider substantive comments timely submitted during the public comment period. The agency may respond to individual comments or groups of comments. In the final environmental impact statement, the agency may respond by:
(1) Modifying alternatives including the proposed action.
(2) Developing and evaluating alternatives not previously given serious consideration by the agency.
(3) Supplementing, improving, or modifying its analyses.
(4) Making factual corrections.
(5) Explaining why the comments do not warrant further agency response, recognizing that agencies are not required to respond to each comment.
(b) An agency shall append or otherwise publish all substantive comments received on the draft statement (or summaries thereof where the response has been exceptionally voluminous).
(c) If changes in response to comments are minor and are confined to the responses described in paragraphs (a)(4) and (5) of this section, an agency may write any changes on errata sheets and attach the responses to the statement instead of rewriting the draft statement. In such cases, only the comments, the responses, and the changes and not the final statement need be published (§ 1502.20 of this chapter). The agency shall file the entire document with a new cover sheet with the Environmental Protection Agency as the final statement (§ 1506.10 of this chapter).