All projects in the STIP must conform to the goals of the federal Clean Air Act Amendments (CAAA) and the related State Implementation Plan for Air Quality. Oregon has nine areas that fall under the CAAA designation of ‘nonattainment or maintenance’ relating to the quality of air. These areas are Portland/Metro Salem/Keizer, Eugene/Springfield, Medford, Grants Pass, Klamath Falls, Lakeview, Oakridge, and La Grande.
All regionally significant projects (those that may impact air quality) proposed for construction in these areas must conform to the goals of the CAAA in order to be approved for funding. A transportation modeling process is used to determine an area’s or project’s conformity. The modeling is complex, expensive and lengthy at usually about four months and upwards of $80,000 per area. Modeling takes place after the public review period for the draft STIP and prior to the approval of the final STIP.