In areas subject to a state implementation plan, no state agency, metropolitan planning organization, or local government shall approve or fund a transportation plan, program, or project within or that affects a nonattainment area unless a determination has been made that the plan, program, or project conforms with the state implementation plan for air quality as required by the federal clean air act.
Conformity determination shall be made by the state or local government or metropolitan planning organization administering or developing the plan, program, or project.
No later than eighteen months after May 15, 1991, the director of the department of ecology and the secretary of transportation, in consultation with other state, regional, and local agencies as appropriate, shall adopt by rule criteria and guidance for demonstrating and assuring conformity of plans, programs, and projects that are wholly or partially federally funded.
A project with a scope that is limited to preservation or maintenance, or both, shall be exempted from a conformity determination requirement.