As part of its transportation planning responsibilities, the WWW Interstate Planning Commission (WWW) completed the transportation conformity determination for the FY 2026–2029 Biennial Transportation Improvement Program (TIP). This report documents that the FY 2026–2029 TIP satisfies all applicable federal conformity requirements under 40 CFR Part 93.
Section 176(c) of the Clean Air Act (42 U.S.C. 7506(c)) requires that federally funded or approved highway and transit activities conform to the purpose of the State Implementation Plan (SIP). Conformity to the SIP means that transportation activities will not cause or contribute to new air quality violations, worsen existing violations, or delay timely attainment of a National Ambient Air Quality Standard (NAAQS) or any required interim milestones (42 U.S.C. 7506(c)(1)). The U.S. Environmental Protection Agency (EPA) establishes the criteria and procedures for transportation conformity determinations in 40 CFR Parts 51.390 and 93.
On February 16, 2018, the United States Court of Appeals for the District of Columbia Circuit issued its decision in South Coast Air Quality Management District v. EPA (“South Coast II,” 882 F.3d 1138). The court held that transportation conformity determinations must continue in areas that were designated nonattainment or maintenance for the 1997 ozone NAAQS and were in attainment for the 2008 ozone NAAQS at the time the 1997 ozone standard was revoked. The reinstated conformity requirements became effective February 16, 2019.
The Parkersburg-Marietta area was designated maintenance for the 1997 ozone NAAQS at the time of its revocation by EPA on April 16, 2015, and had previously been designated attainment for the 2008 ozone NAAQS on May 21, 2012. Accordingly, consistent with the South Coast II decision, this conformity determination for the WWW FY 2024–2027 TIP addresses the 1997 ozone NAAQS.
This conformity determination was completed in accordance with the Clean Air Act, 40 CFR Parts 51.390 and 93, the South Coast II decision, and EPA’s Transportation Conformity Guidance for the South Coast II Court Decision (November 2018).
