Sierra Club v. EPA, 939 F.3d 649

Background:

EPA approved Louisiana’s regional-haze SIP on Dec. 21, 2017; principal disputes concerned LDEQ’s use of the CALPUFF model for “subject-to-BART” screening and LDEQ’s sparse explanation for selecting low-sulfur coal as BART for Unit 6 at the Roy S. Nelson plant.
Two petitions: Environmental Petitioners (Sierra Club & NPCA) challenged the Nelson BART selection and the State’s reasonable-progress goals/long-term strategy; Industry Petitioners (Entergy Louisiana & Cleco) challenged the “subject-to-BART” findings and the technical modeling (CALPUFF and CAMx).
LDEQ relied on CALPUFF to find Nelson and Brame each exceeded the 0.5-deciview contribution threshold; Entergy’s CAMx runs differed, EPA found Entergy’s CAMx invalid and ran its own CAMx, while LDEQ said it lacked CAMx expertise and relied on CALPUFF.
LDEQ picked low-sulfur coal for Nelson after reviewing Entergy’s and EPA’s analyses but provided few supporting numbers, did not reconcile EPA criticisms of Entergy’s cost/visibility inputs, and extended the compliance date by three years.
The Fifth Circuit applied the APA’s arbitrary-and-capricious standard with deference to agency scientific judgments and denied both petitions: it upheld EPA’s approval of (1) LDEQ’s use of CALPUFF and EPA’s review, (2) LDEQ’s BART selection for Nelson (despite weak explanation), and (3) the State’s reasonable-progress/long-term strategy as already addressed by EPA’s 2012 partial limited approval.

Issues:

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether LDEQ’s selection of low-sulfur coal as BART for Nelson was lawful	Env: selection unsupported; ignored EPA analyses showing different cost-effectiveness and benefits; failed to weigh statutory factors or provide numbers	EPA/LDEQ: state reviewed both Entergy and EPA analyses, weighed five factors, and had discretion to choose control	Court: denied challenge; EPA approval not arbitrary and capricious despite LDEQ’s thin explanation given record evidence and deference to state judgment
Whether Louisiana’s reasonable-progress goals and long-term strategy in 2017 SIP were deficient	Env: 2017 SIP failed to revise long-term strategy or impose controls on reasonable-progress sources after 2012 disapproval	EPA: 2012 partial limited approval made the State’s reasonable-progress goals/long-term-strategy provisions effective; no new revision required	Court: denied challenge; 2012 limited approval controlled and issue was not reopened
Whether LDEQ permissibly used CALPUFF for "subject-to-BART" screening (distance, bias, margin of error)	Industry: CALPUFF is flawed, overestimates impacts, unreliable >300 km, margin-of-error issues — so subject-to-BART findings arbitrary	EPA/LDEQ: CALPUFF remains recommended for BART screening, acceptable for large sources with elevated stacks and for consistency; EPA’s CAMx supports results	Court: denied challenge; deferred to EPA’s technical judgment and held CALPUFF use not arbitrary and capricious
Whether EPA erred by relying on its own CAMx or whether some challenges were time-barred	Industry: EPA improperly used CAMx to cure SIP deficiencies and CAMx had technical flaws; also argued parts of attack were time-barred as challenges to 2005 BART guidelines	EPA/Resp: many technical claims concern application not rule; court review not time-barred; but EPA need not rely on CAMx if CALPUFF sufficed	Court: retained jurisdiction and rejected time-bar arguments as to application; because CALPUFF was upheld, court did not decide CAMx merits

Key Cases Cited

Texas v. EPA, 829 F.3d 405 (5th Cir. 2016) (describing Clean Air Act cooperative federalism and SIP review role)
Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29 (1983) (arbitrary-and-capricious standard for agency action)
Union Elec. Co. v. EPA, 427 U.S. 246 (1976) (states’ discretion in SIP design and EPA’s limited role)
Nat'l Parks Conservation Ass'n v. EPA, 788 F.3d 1134 (9th Cir. 2015) (requirement that EPA meaningfully respond to model-margin-of-error comments)
BCCA Appeal Group v. EPA, 355 F.3d 817 (5th Cir. 2003) (deference to agency on complex scientific modeling)