The purpose of this section is to allow clarifications or changes to a proposal prior to making the threshold determination.

(1) In making threshold determinations, an agency may consider mitigation measures that the agency or applicant will implement.

(2) After submission of an environmental checklist and prior to the lead agency's threshold determination on a proposal, an applicant may ask the lead agency to indicate whether it is considering a DS. If the lead agency indicates a DS is likely, the applicant may clarify or change features of the proposal to mitigate the impacts which led the agency to consider a DS likely. The applicant shall revise the environmental checklist as may be necessary to describe the clarifications or changes. The lead agency shall make its threshold determination based upon the changed or clarified proposal. If a proposal continues to have a probable significant adverse environmental impact, even with mitigation measures, an EIS shall be prepared.

(3) Whether or not an applicant requests early notice under subsection (2), if the lead agency specifies mitigation measures on an applicant's proposal that would allow it to issue a DNS, and the proposal is clarified, changed, or conditioned to include those measures, the lead agency shall issue a DNS.

(4) Environmental documents need not be revised and resubmitted if the clarifications or changes are stated in writing in documents that are attachments to, or incorporate by reference, the documents previously submitted. An addendum may be used, see Part Six.

(5) Agencies may clarify or change features of their own proposal, and may specify mitigation measures in their DNSs, as a result of comments by other agencies or the public or as a result of additional agency planning.

(6) An agency's indication under this section that a DS appears likely shall not be construed as a determination of significance. Likewise, the preliminary discussion of clarifications or changes to a proposal shall not bind the lead agency to a mitigated DNS.

(7) Agencies may specify procedures for enforcement of mitigation measures in their agency SEPA procedures.