309 - 40 CFR 51.309

Section 309 of the Regional Haze Rule deals specifically with nine western states, and the tribes within those states. These states and tribes have the option of submitting plans to reduce regional haze in 16 Class 1 national parks in the Colorado Plateau.

The nine states referenced in the above include:

Source: Western Regional Air Partnership. 2008. What is Section 309? Section 309 Implementation Material. Accessed on 9 September 2013. Available at http://wrapair.org