(a) The timing of the preparation, circulation, submission and public availability of environmental documents is important in achieving the purposes of NEPA. Therefore, the NEPA process shall begin as early as possible in the decisionmaking process.

(b) The EPA publishes a weekly notice in the Federal Register of environmental impact statements filed during the preceding week. The minimum time periods set forth below shall be calculated from the date of publication of notices in the Federal Register. No decision on the proposed action may take place until the later of the following dates:

(1) Ninety days after publication of the notice of availability for a draft environmental impact statement (DEIS). Draft statements shall be available to the public for 15 days prior to any public hearing on the DEIS (40 CFR 1506.6(c)(2)).

(2) Thirty days after publication of the notice of availability for a final environmental impact statement (FEIS). If the FEIS is available to the public within ninety days from the availability of the DEIS, the minimum thirty day period and the minimum nintey day period may run concurrently. However, not less than 45 days from publication of notice of filing shall be allowed for public comment on draft statements prior to filing of the FEIS (40 CFR 1506.10(c)).