Opinion ID: 3180012
Heading Depth: 4
Heading Rank: 1

Heading: EPA’s Visibility Analysis

Text: SRP first disputes EPA’s “cumulative” approach. EPA estimated the visibility improvements that would occur at each of the Class I areas potentially impacted by Coronado’s emissions and then aggregated those improvements. SRP contends this analysis resulted in “a large deciview number” that does not represent the actual perception of visibility conditions at any particular Class I area. SRP’s challenge to EPA’s visibility improvement analysis suffers from two substantial defects. First, EPA considered the “cumulative visibility improvement” resulting from various control technologies “[a]s a supplement” to considering deciview improvements at individual Class I areas. For Coronado, specifically, EPA explained that modeling showed that SCR control technology would result in visibility benefits at each of eleven Class I areas—including the Gila Wilderness Area, which EPA faulted Arizona for failing to consider—as well as on a cumulative basis. See 77 Fed. Reg. at 42,863 tbl.23. In response to Petitioners’ comments critiquing EPA’s ARIZONA EX REL. DARWIN V. USEPA 37 cumulative approach, EPA explained in the Final Rule that “[t]he approach is simply one way of assessing improvements at multiple areas, for consideration along with other visibility metrics.” 77 Fed. Reg. at 72,532. SRP’s claim that EPA “focused on this [cumulative] methodology almost exclusively” is simply not supported by the record. Second, SRP’s insistence on “human perception” as the determinative “cornerstone” for the BART determinations for each individual source is overstated. As discussed above, when promulgating the BART Guidelines, EPA explicitly disagreed “that the degree of improvement should be contingent upon perceptibility” when determining BART for an individual source. 70 Fed. Reg. at 39,129. EPA’s Final Rule provided a fully adequate explanation of its application of the deciview concept in the FIP. Again, one deciview is the minimum visibility difference people can perceive. See Guidelines at 39,120 n.32. The Guidelines suggest that states use a minimum threshold of 0.5 deciviews to determine whether a source is subject to BART controls. EPA explained in its Final Rule, however, that “[s]maller improvements from controls should be considered in BART determinations, since they can be beneficial in considering effects from controls on multiple sources.” 77 Fed. Reg. at 72,533 (emphasis added). In conclusion, EPA’s visibility improvement assessment was consistent with the statute and regulatory requirements, and supported by the record. 38 ARIZONA EX REL. DARWIN V. USEPA