(1) In reviewing the environmental impacts of a project and making a threshold determination, a GMA county/city may, at its option, determine that the requirements for environmental analysis, protection, and mitigation measures in the GMA county/city's development regulations and comprehensive plan adopted under chapter 36.70A RCW, and in other applicable local, state, or federal laws or rules, provide adequate analysis of and mitigation for some or all of the specific adverse environmental impacts of the project.

(2) In making the determination under subsection (1) of this section, the GMA county/city shall:

(a) Review the environmental checklist and other information about the project;

(b) Identify the specific probable adverse environmental impacts of the project and determine whether the impacts have been:

(i) Identified in the comprehensive plan, subarea plan, or applicable development regulations through the planning and environmental review process under chapter 36.70A RCW or this chapter, or in other local, state, or federal rules or laws; and

(ii) Adequately addressed in the comprehensive plan, subarea plan, applicable development regulations, or other local, state, or federal rules or laws by:

(A) Avoiding or otherwise mitigating the impacts; or

(B) The legislative body of the GMA county/city designating as acceptable the impacts associated with certain levels of service, land use designations, development standards, or other land use planning required or allowed by chapter 36.70A RCW;

(c) Base or condition approval of the project on compliance with the requirements or mitigation measures in the comprehensive plan, subarea plan, applicable development regulations, or other local, state, or federal rules or laws; and

(d) Place the following statement in the threshold determination if all of a project's impacts are addressed by other applicable laws and no conditions will be required under SEPA: "The lead agency has determined that the requirements for environmental analysis, protection, and mitigation measures have been adequately addressed in the development regulations and comprehensive plan adopted under chapter 36.70A RCW, and in other applicable local, state, or federal laws or rules, as provided by RCW 43.21C.240 and WAC 197-11-158. Our agency will not require any additional mitigation measures under SEPA."

(3) Project specific impacts that have not been adequately addressed as described in subsection (2) of this section might be probable significant adverse environmental impacts requiring additional environmental review. Examples of project specific impacts that may not have been adequately addressed include, but are not limited to, impacts resulting from changed conditions, impacts indicated by new information, impacts not reasonably foreseeable in the GMA planning process, or impacts specifically reserved in a plan EIS for project review.

(4) In deciding whether a project specific adverse environmental impact has been adequately addressed by an existing rule or law of another agency with jurisdiction, the GMA county/city shall consult orally or in writing with that agency and may expressly defer to that agency. In making this deferral, the GMA county/city shall base or condition its project approval on compliance with these other existing rules or laws.

(5) If a GMA county/city's comprehensive plan, subarea plan, or development regulations adequately address some or all of a project's probable specific adverse environmental impacts, as determined under subsections (1) and (2) of this section, the GMA county/city shall not require additional mitigation under this chapter for those impacts.

(6) In making the determination in subsection (1) of this section, nothing in this section requires review of the adequacy of the environmental analysis associated with the comprehensive plans and development regulations that are being relied upon to make that determination.