[Code of Federal Regulations]
[Title 23, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 23CFR771.130]

[Page 412]
 
                           TITLE 23--HIGHWAYS
 
 CHAPTER I--FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
 
PART 771_ENVIRONMENTAL IMPACT AND RELATED PROCEDURES--Table of Contents
 
Sec.  771.130  Supplemental environmental impact statements.

    (a) A draft EIS, final EIS, or supplemental EIS may be supplemented 
at any time. An EIS shall be supplemented whenever the Administration 
determines that:
    (1) Changes to the proposed action would result in significant 
environmental impacts that were not evaluated in the EIS; or
    (2) New information or circumstances relevant to environmental 
concerns and bearings on the proposed action or its impacts would result 
in significant environmental impacts not evaluated in the EIS.
    (b) However, a supplemental EIS will not be necessary where:
    (1) The changes to the proposed action, new information, or new 
circumstances result in a lessening of adverse environmental impacts 
evaluated in the EIS without causing other environmental impacts that 
are significant and were not evaluated in the EIS; or
    (2) The Administration decides to approve an alternative fully 
evaluated in an approved final EIS but not identified as the preferred 
alternative. In such a case, a revised ROD shall be prepared and 
circulated in accordance with Sec.  771.127(b).
    (c) Where the Administration is uncertain of the significance of the 
new impacts, the applicant will develop appropriate environmental 
studies or, if the Administration deems appropriate, an EA to assess the 
impacts of the changes, new information, or new circumstances. If, based 
upon the studies, the Administration determines that a supplemental EIS 
is not necessary, the Administration shall so indicate in the project 
file.
    (d) A supplement is to be developed using the same process and 
format (i.e., draft EIS, final EIS, and ROD) as an original EIS, except 
that scoping is not required.
    (e) A supplemental draft EIS may be necessary for FTA major urban 
mass transportation investments if there is a substantial change in the 
level of detail on project impacts during project planning and 
development. The supplement will address site-specific impacts and 
refined cost estimates that have been developed since the original draft 
EIS.
    (f) In some cases, a supplemental EIS may be required to address 
issues of limited scope, such as the extent of proposed mitigation or 
the evaluation of location or design variations for a limited portion of 
the overall project. Where this is the case, the preparation of a 
supplemental EIS shall not necessarily:
    (1) Prevent the granting of new approvals;
    (2) Require the withdrawal of previous approvals; or
    (3) Require the suspension of project activities; for any activity 
not directly affected by the supplement. If the changes in question are 
of such magnitude to require a reassessment of the entire action, or 
more than a limited portion of the overall action, the Administration 
shall suspend any activities which would have an adverse environmental 
impact or limit the choice of reasonable alternatives, until the 
supplemental EIS is completed.

[52 FR 32660, Aug. 28, 1987, as amended at 70 FR 24470, May 9, 2005]