45 C.F.R. § 900.401

(a) The Commission shall publish a NOI, as described in 40 CFR 1508.22, in the Federal Register as soon as practicable after a decision is made to prepare an EIS, in accordance with 40 CFR 1501.7. If there will be a lengthy period of time between the Commission's decision to prepare an EIS and its actual preparation, the Commission may defer publication of the NOI until a reasonable time before preparing the EIS, provided that the Commission allows a reasonable opportunity for interested parties to participate in the EIS process. Consistent with § 900.201(b), the Commission and the applicant will coordinate during the time period prior to the publication of the NOI to identify: the scope of the action, potential modifications to the proposal, potential alternatives, environmental constraints, potential timeframes for the environmental review, and federal, state, or tribal entities that could be interested in the project, including those with the potential to become cooperating agencies. Through the NOI, the Commission shall invite comments and suggestions on the scope of the EIS.

(b) Publication of the NOI in the Federal Register shall begin the public scoping process. The public scoping process for a Commission EIS shall allow a minimum of 30 days for the receipt of public comments.