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G. Supplemental EISs

In This Section You Will Learn

  • what is a supplemental EIS; and,
  • when is a supplemental EIS required.

1. What is a supplemental EIS?

A supplemental EIS provides an analysis of one or more significant adverse environment impacts which were not addressed, or inadequately addressed, in a draft or final EIS. A supplemental EIS may also be required to analyze the site-specific effects of an action previously discussed in a generic EIS.

2. When is a supplemental EIS needed?

A supplemental EIS may be required if:

  • the project sponsor proposes project changes which may result in one or more significant adverse environmental impacts not addressed in the original EIS;
  • the lead agency discovers new information, not previously available, concerning significant adverse impacts;
  • a change in circumstances arises which may result in a significant adverse environmental impact(s); or
  • site-specific or project-specific analysis of potential significant adverse environmental impact(s) is needed for actions following a generic EIS.

3. Are there criteria for determining if newly discovered information warrants preparation of a Supplemental EIS?

Yes. The lead agency is directed to consider:

  • the importance and relevance of the information; and
  • the present state of the information provided in the original EIS.

The information must be relevant to the discussion of significant adverse environmental impacts, and important for the accuracy of the assessment of those impacts. The information should be genuinely new, that is, the lead agency would have had no reasonable means of knowing that information sooner. The lead agency should evaluate the existing EIS in light of the new information, to be certain that relevant issues have not already been covered in sufficient detail. Further, the scope of the supplemental EIS should be limited to a re-assessment of the relevant significant adverse environmental impacts based on the new information identified.

4. What constitutes a "change in circumstances" as applied to a supplemental EIS?

A "change in circumstances" means any change in the physical setting of, or regulatory standards applicable to, the proposed project. For example, if nearby land uses have changed since the original site assessment was conducted, or the municipality has enacted new land use rules, and these changes are relevant to significant adverse environmental impacts, then a supplemental EIS may be warranted.

5. At what time in the SEQR process may a supplemental EIS be required?

A lead agency may require a supplemental EIS at any time during review of an EIS. For example, the lead agency may determine, based on comments received from involved agencies or the public, to require a supplemental EIS prior to preparing a final EIS. Alternatively, if a project sponsor proposes major project changes which could change the lead agency's identification and assessment of likely significant adverse environmental impacts, a supplemental EIS may be required after the lead agency has accepted the final EIS and issued its finding statement.

For generic EISs, supplements after findings are typical. Potential need for future site-specific or project-specific analysis is inherent in the concept of generic EISs.

6. May a supplemental EIS be required by an agency other than the original lead agency?

As long as the original lead agency retains decision-making power, no other involved agency can force the preparation of a supplemental EIS. This would extend through the lead agency's filing of its findings statement and issuance of its final decision.

After the lead agency has issued its findings statement and final decision, however, any project modification which was not addressed in the EIS but which may have significant adverse environmental impacts, may be subject to a supplemental EIS (or a new EIS, if the modification is so substantial as to be essentially a new project). The original lead agency may continue in its role if it will have regulatory jurisdiction over the modification, or another involved agency which must approve the modification may be established as lead. Any such re-establishment of lead agency requires the concurrence of all involved agencies.

In the case of a generic EIS, the involved agencies may agree in advance that a second involved agency will conduct a site-specific SEQR analysis, once the original lead agency has made its initial decision based on its generic EIS findings. An example of this would be the preparation of a generic EIS for a countywide solid waste management plan, based on which the county-level lead agency selects a specific site and waste disposal method, and following which the state regulatory agency must conduct a project-specific environmental review.

7. How should an agency proceed if it concludes that a final EIS must be supplemented?

The SEQR regulations require that a supplemental EIS be subject to the full procedures required for any other EIS. Thus, when a supplemental EIS is required after a draft or final EIS, the following steps apply:

  • the lead agency should document its assessment of the impacts which are the basis for requiring the supplemental EIS, preferably using a full EAF;
  • the lead agency must prepare and file a notice of intent to prepare a supplemental EIS, that is, a positive declaration;
  • the lead agency may choose to conduct scoping;
  • the lead agency must prepare or review the draft supplemental EIS to determine whether the document is adequate for public review;
  • once the draft supplemental EIS is accepted, the lead agency must notice and conduct a public review period;
  • the lead agency may choose to conduct a hearing on the supplement;
  • the lead agency must respond to comments, prepare a final supplemental EIS including comments plus responses, and file notice of the completion of the document; and
  • the lead agency and all other involved agencies must then make their findings.

9. Who is responsible for preparing a supplemental EIS?

For projects involving applications for governmental approvals, supplemental EISs are typically prepared by the project sponsor. However, as with all EISs, a supplemental EIS must be reviewed and accepted by the lead agency, and the content of a final supplemental EIS remains the responsibility of the lead agency.



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