6. Using SEPA in Decision Making

One of the most important aspects of the SEPA process is the consideration of environmental impacts and possible mitigation measures during agency decision-making. SEPA substantive authority [WAC 197-11-660] gives all levels of government the ability to condition or deny a proposal based on environmental impacts.


Substantive authority is an essential part of SEPA. It allows decision-makers to use the environmental analysis required under SEPA to condition or deny proposals. Without this authority, "...the law would create meaningless and wasteful paperwork . . ." [Ten Years' Experience with SEPA, Final Report of the Commission on Environmental Policy, June 1983, pg. 11].


Before requiring mitigation measures under SEPA substantive authority, agencies are to first consider whether local, state, or federal requirements and enforcement would mitigate the identified significant adverse impacts [WAC 197-11-660(1)(e)].

Decision-makers should judge whether possible mitigation measures are likely to protect or enhance environmental quality. Mitigation measures must be related to a specific adverse impact clearly identified in an environmental document [WAC 197-11-744] on the proposal, and must be reasonable and capable of being accomplished [WAC 197-11-660(1)(b) and (c)].

Mitigation must be included as permit conditions to be enforceable. The exception is when a proponent alters the permit application(s) to include the needed changes or conditions.

Identification of mitigation in a DNS or EIS alone is not sufficient to allow enforcement.

When using SEPA substantive authority, the decision-maker must:

  1. Cite the agency SEPA policy that is the basis for conditioning or denying the proposal;

  2. Document the decision in writing; and

  3. Make available to the public a document that states the decision, and any mitigation measures will be required. This document may be the permit, license, or approval; or it may be combined with other agency documents; or the decision document may reference relevant portions of environmental documents.

To deny a proposal under SEPA, an agency must find that:

  1. The proposal would be likely to result in a significant adverse environmental impact identified in a final EIS or final supplemental EIS; and

  2. Reasonable mitigation measures are not sufficient to mitigate the identified impact to a non-significant level.

SEPA supplements the existing authority of all agencies. To exercise SEPA substantive authority each agency must adopt SEPA policies that will be the basis for conditioning or denying proposals. These policies must be readily available to the public for the benefit of applicants and concerned citizens. (See adoption procedures in WAC 197-11-902.)


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