City of Port Isabel v. Federal Energy Regulatory Commission

United States Court of Appeals
FOR THE DISTRICT OF COLUMBIA CIRCUIT
Argued May 17, 2024 Decided August 6, 2024
No. 23-1174
C ITY OF P ORT ISABEL, ET AL.,
P ETITIONERS
v.
F EDERAL ENERGY R EGULATORY C OMMISSION,
R ESPONDENT
R IO B RAVO P IPELINE C OMPANY , LLC AND R IO G RANDE LNG,
LLC,
INTERVENORS
Consolidated with 23-1221
On Petitions for Review of Orders of the
Federal Energy Regulatory Commission
Nathan Matthews argued the cause for petitioners. With
him on the joint briefs were Lisa M. Diaz, Tom Gosselin, and
Gilberto Hinojosa. Eric E. Huber entered an appearance.

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Robert M. Kennedy, Senior Attorney, Federal Energy
Regulatory Commission, argued the cause for respondent.
With him on the brief were Matthew R. Christiansen, General
Counsel, and Robert H. Solomon, Solicitor. Jason Perkins,
Attorney, entered an appearance.
Varu Chilakamarri argued the cause for intervenors Rio
Bravo Pipeline Company, LLC and Rio Grande LNG, LLC in
support of respondent. With her on the joint briefs were Jeremy
C. Marwell, Matthew X. Etchemendy, David L. Wochner, and
John Longstreth. James Dawson, Timothy J. Furdyna, James
D. Seegers, and Paul M. Teague entered appearances.

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No. 23-1175
C ITY OF P ORT ISABEL AND S IERRA C LUB ,
P ETITIONERS
v.
F EDERAL ENERGY R EGULATORY C OMMISSION,
R ESPONDENT
TEXAS LNG B ROWNSVILLE, LLC,
INTERVENOR
Consolidated with 23-1222
On Petitions for Review of Orders of the
Federal Energy Regulatory Commission
Nathan Matthews argued the cause for petitioners. With
him on the joint briefs were Lisa M. Diaz, Tom Gosselin, and
Gilberto Hinojosa.
Robert M. Kennedy, Senior Attorney, Federal Energy
Regulatory Commission, argued the cause for respondent.
With him on the brief were Matthew R. Christiansen, General

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Counsel, Robert H. Solomon, Solicitor, and Jason Perkins,
Attorney.
Michael R. Pincus argued the cause for intervenor Texas
LNG Brownsville, LLC in support of respondent. With him on
the brief were Paul Korman and Mosby Perrow.
Before: S RINIVASAN, Chief Judge, C HILDS and GARCIA,
Circuit Judges.
Opinion for the Court filed by Circuit Judge GARCIA.
GARCIA, Circuit Judge: In 2021, petitioners challenged
the Federal Energy Regulatory Commission’s authorization of
two liquefied natural gas export terminals in Cameron County,
Texas, and a pipeline that would carry natural gas to one of
those terminals. In related decisions, we granted the petitions
for review in part and remanded without vacatur. Vecinos para
el Bienestar de la Comunidad Costera v. FERC (“Vecinos I”),
6 F.4th 1321, 1325 (D.C. Cir. 2021); Vecinos para el Bienestar
de la Comunidad Costera v. FERC (“Vecinos II”), No. 20-
1045, 2021 WL 3716769 (D.C. Cir. Aug. 3, 2021)
(unpublished opinion). On remand, the Commission issued
orders reauthorizing the projects.
Petitioners now challenge the reauthorization orders.
They argue that the Commission failed to comply with certain
National Environmental Policy Act and Natural Gas Act
requirements. Once again, we agree in part. The Commission
erroneously declined to issue supplemental environmental
impact statements addressing its updated environmental justice
analysis for each project and its consideration of a carbon
capture and sequestration system for one of the terminals. It
also failed to explain why it declined to consider air quality
data from a nearby air monitor. We deny the petitions in all

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other respects. Given the nature and severity of the flaws in the
Commission’s second effort to properly assess the projects, we
vacate the reauthorization orders and remand to the
Commission for further consideration.
I
A
Under Section 3 of the Natural Gas Act (“NGA”), the
Commission exercises authority delegated from the
Department of Energy “to approve or deny an application for
the siting, construction, expansion, or operation of” facilities
used to export liquefied natural gas (“LNG”). 15 U.S.C.
§ 717b(e)(1); see EarthReports, Inc. v. FERC, 828 F.3d 949,
952–53 (D.C. Cir. 2016). The Commission “shall” approve
such an application unless it finds that the project “will not be
consistent with the public interest.” 15 U.S.C. § 717b(a); see
EarthReports, 828 F.3d at 953.
Under Section 7 of the NGA, the Commission reviews
applications for the construction and operation of pipelines that
transport natural gas in interstate commerce. 15 U.S.C.
§ 717f(c); Allegheny Def. Project v. FERC, 964 F.3d 1, 4 (D.C.
Cir. 2020). The Commission “shall” authorize such a pipeline
if it “is or will be required by the present or future public
convenience and necessity.” 15 U.S.C. § 717f(e); see
Allegheny Def. Project, 964 F.3d at 4.
“Before authorizing the construction and operation of a
proposed LNG facility or pipeline, the Commission must
conduct an environmental review under” the National
Environmental Policy Act (“NEPA”). Vecinos I, 6 F.4th at
1325. If, as here, the Commission determines that approval of
the facility constitutes a “major Federal action[] significantly
affecting the quality of the human environment,” the

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Commission must prepare an Environmental Impact Statement
(“EIS”). 42 U.S.C. § 4332(2)(C); see id. § 4336(b)(1). Among
other things, the EIS must address the “reasonably foreseeable
environmental effects” of the proposed action as well as “a
reasonable range of alternatives . . . that are technically and
economically feasible, and meet the purpose and need of the
proposal.” Id. § 4332(2)(C)(i), (iii). The EIS “forces the
[Commission] to take a ‘hard look’ at the environmental
consequences of its actions” and “ensures that [those]
consequences, and the [Commission’s] consideration of them,
are disclosed to the public.” Sierra Club v. FERC (“Sabal
Trail”), 867 F.3d 1357, 1367 (D.C. Cir. 2017).
B
This case concerns two proposed natural gas projects. On
March 30, 2016, Texas LNG Brownsville LLC (“Texas LNG”)
filed a Section 3 application for authorization to construct and
operate an LNG export terminal on the northern shore of the
Brownsville Shipping Channel in Cameron County, Texas. On
May 5, 2016, Rio Grande LNG, LLC (“Rio Grande”) filed a
Section 3 application for authorization to construct and operate
its own LNG export terminal at a different site on the same
shore. Rio Bravo Pipeline Company, LLC (“Rio Bravo”)
simultaneously filed a related Section 7 application for
authorization to construct and operate a new interstate pipeline
system to deliver natural gas from existing grid interconnects
in Nueces County, Texas, to the Rio Grande terminal. The Rio
Grande terminal and Rio Bravo pipeline together form the Rio
Grande project.1
1 Rio Grande and Rio Bravo are both wholly owned subsidiaries
of NextDecade LNG, LLC, a U.S. energy project development and
management company.

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After publishing a final EIS for each project, on November
22, 2019, the Commission issued orders authorizing the
projects. See Order Granting Authorizations Under Sections 3
and 7 of the Natural Gas Act, Rio Grande LNG, LLC & Rio
Bravo Pipeline Co., 169 FERC ¶ 61,131 (Nov. 22, 2019);
Order Granting Authorization Under Section 3 of the Natural
Gas Act, Texas LNG Brownsville LLC, 169 FERC ¶ 61,130
(Nov. 22, 2019) (collectively, the “2019 Approval Orders” or
“authorization orders”).
Petitioners—environmental groups, residents, and the
nearby city of Port Isabel—intervened in the Commission’s
proceedings and sought rehearing of the authorization orders.
They argued that the Commission’s analyses of the projects’
ozone emissions and impacts on climate change and
environmental justice communities were deficient under
NEPA and the Administrative Procedure Act (“APA”). They
also claimed that the Commission failed to justify its
determinations of public interest and convenience under the
NGA. Regarding the Rio Grande project, petitioners further
argued that the Commission violated NEPA by failing to
adequately analyze alternative project designs.
After the Commission denied their rehearing requests,
petitioners sought review in our court. On August 3, 2021, we
addressed petitioners’ challenges to the authorization orders in
two companion decisions. Vecinos I, 6 F.4th 1321; Vecinos II,
2021 WL 3716769.
In Vecinos I, we held that the Commission failed to
adequately justify its decision to examine environmental
justice impacts within only a two-mile radius of the projects,
when some environmental impacts of the projects would
extend beyond that area. See 6 F.4th at 1330–31. Thus, we
instructed the Commission to either better explain its reasoning

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or analyze the projects’ impacts within a different radius. Id.
at 1331. We also directed the Commission to respond to
petitioners’ argument that 40 C.F.R. § 1502.21(c) (2020)2
required it to use the social cost of carbon protocol or some
other generally accepted methodology to assess whether the
climate impact of the projects’ greenhouse gas (“GHG”)
emissions would be significant or not. See id. at 1328–30.
Given the deficiencies in the Commission’s environmental
analyses, we further directed the Commission to reconsider its
NGA public interest determinations for the projects. Id. at
1331 (citing 15 U.S.C. §§ 717b(a), 717f(e)). Ultimately, we
remanded without vacatur because we found it likely that the
Commission could remedy the deficiencies while reaching the
same result. Id. at 1332.
In Vecinos II, we “denied in all respects” the other
challenges petitioners raised to the authorization orders.
2021 WL 3716769, at *1.
In November 2021, in response to our remand, Rio Grande
filed on a separate docket a proposal to add a carbon capture
and sequestration (“CCS”) system to its terminal design. The
system would employ processes to remove carbon dioxide
emissions during natural gas liquefaction and then transport
those emissions by pipeline to an EPA- and state-authorized
underground injection well for sequestration. Rio Grande
projected that the system would capture at least 90% of the
2 The Council on Environmental Quality regulations cited here
and elsewhere in the opinion have since been amended, but those
amendments did not take effect until after the Commission entered
the challenged orders. See National Environmental Policy Act
Implementing Regulations Revisions Phase 2, 89 Fed. Reg. 35,442
(May 1, 2024) (effective July 1, 2024). Thus, we cite and apply the
regulations in effect at the time of the orders. See Ctr. for Biological
Diversity v. FERC, 67 F.4th 1176, 1181 n.2 (D.C. Cir. 2023).

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carbon dioxide produced at the terminal. The company asked
the Commission to consider the CCS proposal at the same time
it considered reauthorization of the existing project.
Commission staff initially anticipated issuing an
environmental assessment of the CCS system in May 2023 but
suspended those plans after Rio Grande failed to provide
“complete and timely responses” to several data requests by the
agency. Notice Suspending Environmental Review Schedule
of the Proposed Carbon Capture and Sequestration System
Amendment, 88 Fed. Reg. 24,407 (Apr. 20, 2023).
On April 21, 2023, the Commission issued orders
reauthorizing the projects. See Order on Remand and
Amending Section 7 Certificate (“No. 23-1174 Remand
Order”), Rio Grande LNG, LLC & Rio Bravo Pipeline Co., 183
FERC ¶ 61,046 (Apr. 21, 2023); Order on Remand (“No. 23-
1175 Remand Order”), Texas LNG Brownsville LLC, 183
FERC ¶ 61,047 (Apr. 21, 2023) (collectively, the “Remand
Orders”). Petitioners filed timely requests for rehearing, but
after the Commission failed to respond within thirty days, the
requests were deemed denied by operation of law.
On July 10, 2023, petitioners asked this court to review the
Remand Orders. City of Port Isabel v. FERC, No. 23-1174
(D.C. Cir.) (Rio Grande project); City of Port Isabel v. FERC,
No. 23-1175 (D.C. Cir.) (Texas project). We granted Rio
Grande, Rio Bravo, and Texas LNG leave to intervene. On
October 27, 2023, while the petitions were pending, the
Commission issued orders addressing the rehearing requests
and sustaining the reauthorizations. See Order Addressing
Arguments Raised on Rehearing (“No. 23-1174 Rehearing
Order”), Rio Grande LNG, LLC & Rio Bravo Pipeline Co., 185
FERC ¶ 61,080 (Oct. 27, 2023); Order Addressing Arguments
Raised on Rehearing (“No. 23-1175 Rehearing Order”), Texas
LNG Brownsville LLC, 185 FERC ¶ 61,079 (Oct. 27, 2023).

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II
We review petitioners’ claims under the familiar “arbitrary
and capricious” standard. Nevada v. U.S. Dep’t of Energy, 457
F.3d 78, 87 (D.C. Cir. 2006); Vecinos I, 6 F.4th at 1331. “Our
role is not to flyspeck an agency’s environmental analysis,
looking for any deficiency no matter how minor, but instead
simply to ensure that the agency has adequately considered and
disclosed the environmental impact of its actions and that its
decision is not arbitrary or capricious.” Birckhead v. FERC,
925 F.3d 510, 515 (D.C. Cir. 2019) (per curiam) (citations and
quotation marks omitted). We therefore ask whether the
agency “examine[d] the relevant data and articulate[d] a
satisfactory explanation for its action[,] including a rational
connection between the facts found and the choice made.”
Motor Vehicle Mfrs. Ass’n, Inc. v. State Farm Mut. Auto. Ins.
Co., 463 U.S. 29, 43 (1983) (citation and quotation marks
omitted).
Petitioners challenge several aspects of the Commission’s
orders. We consider each in turn.
A
We begin with the Commission’s environmental justice
analysis. “In conducting NEPA reviews of proposed natural
gas projects, the Commission follows Executive Order
12[,]898, which directs federal agencies to identify and address
‘disproportionately high and adverse human health or
environmental effects’ of their actions on minority and low-
income populations (i.e., environmental justice communities).”
No. 23-1174 Remand Order ¶ 103 (quoting Executive Order
12,898, 59 Fed. Reg. 7,629 (Feb. 11, 1994)); see Sabal Trail,
867 F.3d at 1368. The Commission’s methodology considers:
“(1) whether environmental justice communities . . . exist in
the project area; (2) whether impacts on environmental justice

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communities are disproportionately high and adverse; and (3)
possible mitigation measures.” No. 23-1174 Remand Order
¶ 104.
In Vecinos I, we held that the Commission’s
environmental justice analysis of the projects was arbitrary.
The Commission did not adequately explain why, despite its
“determination that environmental effects from the project
would extend well beyond two miles from the project sites,” it
nonetheless “chose to analyze the projects’ impacts only on
communities . . . within two miles of the project sites.” 6 F.4th
at 1330, 1331. We remanded for the Commission to either
provide such an explanation “or else analyze the projects’
impacts on communities within a different radius of each
project site.” Id. We also required the Commission to “explain
whether its finding that ‘all project-affiliated populations are
minority or low-income populations,’ is still justified, and, if
so, whether its conclusion that the projects ‘would not have
disproportionate adverse effects on minority and low-income
residents in the area’ still holds.” Id. (quoting the 2019
Approval Orders).
On remand, the Commission generated a new and
significantly expanded environmental justice analysis for each
project. It first issued several information requests to the
developers, seeking updated demographic information for
census block groups within fifty kilometers (thirty-one miles)
of the project and updated models for emissions within that
same geographic scope. “Commission staff” then “conducted
a new environmental justice analysis.” No. 23-1174 Remand
Order ¶ 102; No. 23-1175 Remand Order ¶ 26. The
Commission did not prepare its analysis in the form of a
supplemental environmental impact statement (“supplemental
EIS”). Doing so would have required the agency to publish a
draft supplemental EIS, provide a forty-five-day period for

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public comment on that draft, and allow interested parties to
intervene—procedural steps the Commission skipped here.
See 40 C.F.R. §§ 1502.9(d)(3), 1506.11(d) (2020); 18 C.F.R.
§ 380.10(a)(1)(i).
Petitioners argue that the Commission’s choice not to issue
a supplemental EIS for its environmental justice analysis was
arbitrary and capricious and prejudiced their ability to
comment meaningfully on the Commission’s new
environmental justice analysis. We agree.
1
NEPA regulations require a supplemental EIS when
“[t]here are significant new circumstances or information
relevant to environmental concerns and bearing on the
proposed action or its impacts.” 40 C.F.R. § 1502.9(d)(1)(ii)
(2020). This requirement applies to new circumstances or
information that “will ‘affect the quality of the human
environment’ in a significant manner or to a significant extent
not already considered,” Marsh v. Or. Nat. Res. Council, 490
U.S. 360, 374 (1989) (quoting 42 U.S.C. § 4332(2)(C))
(cleaned up), or that “provides a seriously different picture of
the environmental landscape,” Stand Up for California! v.
Dep’t of Interior, 994 F.3d 616, 629 (D.C. Cir. 2021) (quoting
Friends of Cap. Crescent Trail v. Fed. Transit Admin., 877
F.3d 1051, 1060 (D.C. Cir. 2017)) (emphasis omitted).
Here, the pertinent “new information” includes the
updated demographic and environmental data submitted by the
developers, as well as the Commission’s entirely new analysis
and interpretation of that data, which are substantially different
from the previously conducted environmental justice analysis
in the final EIS. See No. 23-1174 Remand Order ¶¶ 102–206;
No. 23-1175 Remand Order ¶¶ 26–82; see also No. 23-1175
J.A. 126 (Chairman Phillips’s concurrence describing that the

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Commission “conducted a full review of the projects’ impacts
on environmental justice communities” in response to remand).
Contrary to the Commission’s view, the scope and nature of
that new information and analysis “provide[] a seriously
different picture of the environmental landscape” and require a
supplemental EIS. Stand Up, 994 F.3d at 629 (emphasis and
quotation omitted).
To begin, the previous environmental justice analysis in
the final EIS analyzed the projects’ impacts on communities
within a two-mile radius of the projects, which included four to
five census blocks. See No. 23-1174 J.A 266; No. 23-1175 J.A.
237. On remand, the Commission analyzed the projects’
impacts on communities within a fifty-kilometer (or thirty-one-
mile) radius, which covered over 373 census block groups of
environmental justice communities. No. 23-1174 Remand
Order ¶¶ 204–05 (286 block groups impacted by Rio Grande
terminal and eighty-seven impacted by Rio Bravo pipeline);
No. 23-1175 Remand Order ¶ 82 (279 block groups impacted
by Texas project). The new analysis expanded the discussion
from a mere five pages to forty-six pages for the Rio Grande
project, with a similar increase for the Texas project. Compare
No. 23-1174 J.A. 263–68 (Rio Grande project’s five-page final
EIS analysis), and No. 23-1175 J.A. 236–39, 273–74 (Texas
project’s five-page final EIS analysis), with No. 23-1174
Remand Order ¶¶ 102–206 (Rio Grande’s forty-six-page new
analysis), and No. 23-1175 Remand Order ¶¶ 26–82 (Texas
project’s twenty-six-page new analysis). In those pages, the
new analysis acknowledges, for example, that “potential
impacts on the identified environmental justice communities
may relate to wetlands, recreational and subsistence fishing,
tourism, socioeconomics, road and marine traffic, noise, safety,
air quality, and visual resources,” No. 23-1174 Remand Order
¶ 110; No. 23-1175 Remand Order ¶ 35, and proceeds to
analyze those categories of impacts and more through the

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environmental justice lens. That new analysis also relied on
updated cumulative air emissions data. See No. 23-1174
Remand Order ¶ 137; No. 23-1175 Remand Order ¶ 76.
The Commission’s new environmental justice analysis
also arrived at different conclusions. Most fundamentally,
prior to remand, the Commission found that the projects would
not have any “disproportionate adverse effects” on
environmental justice communities. No. 23-1174 J.A. 267–68;
No. 23-1175 J.A. 239. Yet in its updated analysis, the
Commission concluded that “the impacts on environmental
justice populations from the project would be
disproportionately high and adverse because they would be
predominately borne by the environmental justice communities
identified and, specifically, communities in the areas near the
[projects] may experience significant visual impacts, as well as
significant cumulative visual impacts.” No. 23-1175 Remand
Order ¶ 83; No. 23-1174 Remand Order ¶ 207. Moreover, the
Commission ordered additional mitigation measures, beyond
what it originally ordered, to address certain potential air
quality impacts at public recreational areas close to the project
sites. See No. 23-1174 Remand Order ¶¶ 140–41; No. 23-1175
Remand Order ¶¶ 68–69.
The combination of these factors persuades us that a
supplemental EIS was required. This case is meaningfully
different from those in which we have not disturbed agencies’
decisions not to issue a supplemental EIS, such as where the
“new” information was only updated information about an
issue that the agency had already considered adequately and to
a similar extent, see Friends of Cap. Crescent Trail, 877 F.3d
at 1060–61; Stand Up, 994 F.3d at 629; Nat’l Comm. for the
New River v. FERC, 373 F.3d 1323, 1330 (D.C. Cir. 2004);
Vecinos II, 2021 WL 3716769, at *2, and cases in which the
agency was presented with new information from an outside

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party and did not trust the validity of that information at all, see
Friends of the River v. FERC, 720 F.2d 93, 109 (D.C. Cir.
1983); Marsh, 490 U.S. at 374. Here, the Commission not only
trusted the validity of the new demographic and emissions data
but used that data to “conduct[] a new environmental justice
analysis” for a significantly expanded geographic scope and
arrived at new conclusions. No. 23-1174 Remand Order ¶ 102;
No. 23-1175 Remand Order ¶ 26.
For its part, the Commission stated that it “was not
required to prepare a supplemental EIS because the issues
addressed on remand did not result in any new significance
determinations,” insofar as Commission staff “concluded that
there would be no significant impact on air quality from the
project.” No. 23-1175 Rehearing Order ¶ 31; No. 23-1174
Rehearing Order ¶ 42 (similar).
That explanation is inadequate for two related reasons.
First, neither the regulations nor case law condition the
requirement to issue a supplemental EIS on a new
determination that a particular environmental impact is
significant. As stated above, our cases describe the
requirement as triggered by a “seriously different picture of the
environmental landscape,” Stand Up, 994 F.3d at 629
(emphasis and quotation omitted), not solely whether the
agency makes a new significance finding. Indeed, NEPA
requires an EIS if any significant impacts “might result” from
the proposed action, not only when it definitively concludes
that a significant impact will result. Grand Canyon Trust v.
FAA, 290 F.3d 339, 340 (D.C. Cir. 2002) (quoting Sierra Club
v. Peterson, 717 F.2d 1409, 1415 (D.C. Cir. 1983)) (emphasis
added). The same logic applies to the issuance of a
supplemental EIS, and that logic contradicts the Commission’s
bright-line approach.

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Second, the unavoidable implication of the Commission’s
argument is that environmental justice analyses—even new
and dramatically expanded ones—are not important enough to
require a supplemental EIS unless they also disclose significant
impacts to the physical environment. See No. 23-1174
Rehearing Order ¶¶ 42–43; No. 23-1175 Rehearing Order
¶¶ 31–32. But environmental justice analyses and impacts can
be sufficiently meaningful to require a supplement on their
own.
The requirement for a supplemental EIS itself states that
there must be “significant new circumstances or information
relevant to environmental concerns and bearing on the
proposed action or its impacts.” 40 C.F.R. § 1502.9(d)(1)(ii)
(2020). Effects on environmental justice communities are
certainly “impacts” that are “relevant to environmental
concerns”: NEPA regulations define relevant “impacts” to
mean “changes to the human environment from the proposed
action” including “ecological (such as the effects on natural
resources and on the components, structures, and functioning
of affected ecosystems), aesthetic, historic, cultural, economic,
social, or health” effects. 40 C.F.R. § 1508.1(g) (2022); see id.
§ 1508.1(m).3
In fact, CEQ and EPA guidance—on which the
Commission relies—reinforces the notion that effects on
3 Indeed, the new regulations effective July 1, 2024, explicitly
add “disproportionate and adverse effects on communities with
environmental justice concerns” to this list of relevant effects, 40
C.F.R. § 1508.1(i)(4), and the CEQ explained that the change was
designed to “provide[] further specificity” and “not [to] expand the
scope of the definition of ‘effects,’” National Environmental Policy
Act Implementing Regulations Revisions Phase 2, 89 Fed. Reg. at
35,539.

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environmental justice communities can be independently
significant. See, e.g., CEQ, Environmental Justice: Guidance
Under the National Environmental Policy Act, at 10 (Dec. 10,
1997), https://perma.cc/773N-3WXX (“Agency consideration
of impacts on low-income populations, minority populations,
or Indian tribes may lead to the identification of
disproportionately high and adverse human health or
environmental effects that are significant and that otherwise
would be overlooked.” (emphasis added)); EPA, Promising
Practices for EJ Methodologies in NEPA Reviews, at 33
(2016), https://perma.cc/ZQ8H-YA4H (“The impacts of a
proposed action on minority populations and low-income
populations should inform the determination of whether
impacts are significant.”).
Therefore, at least where, as here, the Commission issued
an entirely new and significantly expanded environmental
justice analysis that reached new conclusions, we hold that the
Commission needed to issue a supplemental EIS. Its failure to
do so was arbitrary and capricious.4
4 Petitioners separately argue that a supplemental EIS is always
required to remedy a deficient EIS, regardless of whether the new
information meets the standard articulated in 40 C.F.R.
§ 1502.9(d)(1)(ii)—that is, regardless of whether there are
“significant new circumstances or information relevant to
environmental concerns.” See No. 23-1174 Petitioners’ Brief 25.
The only case petitioners cite for that argument is Idaho Sporting
Congress Inc. v. Alexander, 222 F.3d 562 (9th Cir. 2000), but even
there, the Ninth Circuit found that the new information requiring a
supplemental EIS was “significant,” id. at 567, and explained that the
rule is that “once an agency determines that new information is
significant, it must prepare a supplemental EA or EIS,” id. at 566.
Accordingly, we reject petitioners’ argument and instead assess,

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2
The Commission attempts to save itself from remand by
arguing that even if it were required to issue a supplemental
EIS, its failure to do so was harmless. Our court has recognized
the APA’s “‘rule of prejudicial error’ . . . in the NEPA context
when the agency has undertaken the required analysis but
‘failed to comply precisely with NEPA procedures,’” Oglala
Sioux Tribe v. U.S. Nuclear Regul. Comm’n, 45 F.4th 291, 300
(D.C. Cir. 2022) (quoting Nevada, 457 F.3d at 90), and we will
not remand if it would be “utterly pointless,” NRDC v. U.S.
Nuclear Regul. Comm’n, 879 F.3d 1202, 1212 (D.C. Cir.
2018). We decline to apply that rule here because the
Commission’s error prejudiced petitioners’ and the public’s
ability to comment on the Commission’s environmental justice
analysis.
The Commission did solicit public comment as to some of
the data underlying its environmental justice analysis, but it did
not permit comment on all the relevant data. Even though the
Commission opened a fifteen-day window to receive public
comments on the developers’ responses (including Rio
Grande’s cumulative air emissions data), it did not solicit any
public comment on the final cumulative air emissions model
upon which the Commission eventually relied in its analysis.
See No. 23-1174 Remand Order ¶¶ 82–85 (summarizing
comment process); id. ¶ 137 (explaining reliance on new
model); No. 23-1175 Remand Order ¶¶ 10–12, 76 (similar).
That final model, which contained substantially different
results from the prior model, was submitted to the Commission
on January 6, 2023, after the public comment period closed on
consistent with the regulation and our precedent, whether there are
“significant new circumstances or information relevant to
environmental concerns” requiring issuance of a supplemental EIS.

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November 4, 2022. Compare No. 23-1175 J.A. 457 (April 29,
2022 analysis showing five NAAQS exceedances for the Texas
project), with No. 23-1175 J.A. 504–05 (January 6, 2023
analysis predicting zero NAAQS exceedances for the Texas
project). Indeed, petitioners point out discrepancies in the final
model that they would have investigated further and submitted
comments on had they been given the chance. See No. 23-1174
Petitioners’ Brief 35; No. 23-1175 Petitioners’ Brief 29–30.
The fact that petitioners challenge the validity and
interpretation of the underlying data differentiates this case
from Oglala Sioux, where we did not remand because the
parties did “not dispute the reasonableness or accuracy” of the
agency’s findings. 45 F.4th at 301.
More importantly, the Commission did not permit any
public comment on its analysis. Because the comment period
was limited to the developers’ responses, the public was not
able to comment on the Commission’s analysis of those
responses. See No. 23-1175 J.A. 498–505 (Texas LNG’s
developer response with data but no explanation). But NEPA’s
purpose is to allow the public to see and comment on the
agency’s interpretation of data, not just the underlying data
itself. See Friends of the River, 720 F.2d at 106–07 (explaining
that a supplemental EIS should “present evidence and
discussion relevant to [the agency’s] environmental
decisionmaking in one comprehensive document”).
In sum, the Commission’s error is prejudicial because it
deprived petitioners and the public of an adequate “springboard
for public comment.” Robertson v. Methow Valley Citizens
Council, 490 U.S. 332, 349 (1989). The Commission provided
only a fifteen-day comment period on the developer responses,
while the typical NEPA process would have afforded a forty-
five-day comment period on a draft supplemental EIS—which
would have included not just the developer responses but the

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later-submitted air modeling data and the Commission’s
proposed analysis—and required FERC to “address
comments” in the final version. See 40 C.F.R. §§ 1502.9(b)–
(d), 1506.11(d) (2020). The Commission responds by arguing
that parties could still file letters on the Commission’s docket
after the comment period ended or on rehearing. But filing
letters on the docket (with no guarantee that the Commission
will consider them) is no substitute for commenting on a draft
supplemental EIS because NEPA requires the public to be able
to comment “at a meaningful time.” Marsh, 490 U.S. at 371.
We therefore hold that the Commission’s failure to issue a
supplemental EIS for its environmental justice analysis was
arbitrary and capricious and prejudicial.
B
Next, petitioners argue that, before reauthorizing the Rio
Grande terminal on remand, the Commission needed to
consider the company’s CCS proposal as part of its
environmental review of the terminal. Petitioners advance two
grounds for this argument: (1) the CCS system is a “connected
action” under 40 C.F.R. § 1501.9(e)(1)(ii) (2020); and (2)
inclusion of the CCS system qualifies as an alternative to the
terminal as initially proposed. Both are correct.
1
NEPA regulations state that, in addition to assessing the
project under review, an EIS “shall consider . . . connected
actions.” 40 C.F.R. § 1501.9(e)(1) (2020). As relevant here,
petitioners claim that the CCS proposal is an action
“connected” to the Rio Grande terminal because it “will not
proceed unless” the terminal is constructed “previously or
simultaneously.” Id. § 1501.9(e)(1)(ii).

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To assess whether actions are connected, and thus must be
considered together, we consider whether they have
“substantial independent utility” and whether they overlap
temporally. City of Bos. Delegation v. FERC, 897 F.3d 241,
252 (D.C. Cir. 2018) (quotation omitted). Here, both factors
support finding the actions connected.
At the outset, the parties disagree on the test for substantial
independent utility. The Commission and Rio Grande insist
that two projects are not connected whenever one of the
projects has utility independent of the other. In their view,
because the terminal is useful separate and apart from the CCS
system, the projects are not connected actions. Petitioners, by
contrast, contend that projects have substantial independent
utility in the relevant sense only if both projects are
independently useful. For three reasons, petitioners have the
better argument.
First, the relevant regulation states that “[a]ctions are
connected if they . . . [c]annot or will not proceed unless other
actions are taken previously or simultaneously.” 40 C.F.R.
§ 1501.9(e)(1)(ii) (2020). Read plainly, the regulation suggests
that if any one action cannot or will not proceed without the
other(s), those actions are connected.
Second, the Commission’s view would undermine the
undisputed purpose of the regulation: to stop an agency from
impermissibly segmenting “connected . . . federal actions into
separate projects and thereby fail[ing] to address the true scope
and impact of the activities that should be under consideration.”
Del. Riverkeeper Network v. FERC, 753 F.3d 1304, 1313 (D.C.
Cir. 2014). That concern would obviously be implicated if
projects could escape consolidated review whenever one of
them could proceed without the other. For example, imagine
that an applicant proposed an initial project to build an LNG

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terminal with four liquefaction trains. Suppose the applicant
then proposes to add—as a distinct project—a fifth liquefaction
train to the terminal (and perhaps a sixth, seventh, and so on).
Assume the initial project could stand on its own, but the other
liquefaction-train projects could proceed only if the initial
project were completed. Under the Commission’s reading of
the regulation, those formally distinct projects—though clearly
parts of the same functional development—would be deemed
unconnected for NEPA purposes, allowing the Commission to
segment the projects’ environmental reviews and avoid
addressing their collective environmental impact. That result
would defy the commonsense policy behind the connected-
action regulation.
Third, our previous decisions have already gestured
toward the more stringent test. Although we have not directly
addressed the Commission’s argument, in cases where we have
found substantial independent utility satisfied, we have noted
that each project could proceed without the other(s). See Food
& Water Watch v. FERC, 28 F.4th 277, 291 (D.C. Cir. 2022)
(“The Commission found that each project would have gone
forward absent the other.”); City of Bos. Delegation, 897 F.3d
at 252 (“[T]he projects do not depend on the other[s] for access
to the natural gas market.” (second alteration in original));
Myersville Citizens for a Rural Cmty., Inc. v. FERC, 783 F.3d
1301, 1326 (D.C. Cir. 2015) (“[T]he Commission in this case
made clear that the Allegheny Storage Project and the Cove
Point LNG terminal are unrelated, and that neither depends on
the other for its justification.”).
Accordingly, we hold that projects have substantial
independent utility for purposes of the connected-action
inquiry only when both projects are independently useful.
Applied here, that factor favors connectedness because, as
neither the Commission nor Rio Grande disputes, the proposed

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CCS system is entirely dependent on the Rio Grande terminal
for its utility.
The temporal-overlap factor also supports finding that the
CCS system is a connected action. This factor generally asks
whether the projects are “either under construction” or
“pending before the Commission for environmental review and
approval” at the same time. Del. Riverkeeper, 753 F.3d at
1308. Here, the Commission emphasizes that it completed its
initial environmental analysis of the Rio Grande terminal and
approved that project in November 2019, two years before the
company filed its CCS proposal. But that is not the whole
story. Rio Grande submitted its CCS proposal specifically in
response to our 2021 remand—which required the Commission
to revisit aspects of its environmental analysis and its ultimate
approval of the project—such that both approval requests were
pending before the Commission at the same time. Indeed, Rio
Grande implored the Commission to consider the CCS
proposal as part of the reauthorization process precisely
because it viewed the two actions as related and thought that
the CCS proposal’s ability to capture most of the terminal’s
GHG emissions would make reauthorization more likely. See
No. 23-1174 J.A. 715.
The Commission’s view that the Rio Grande terminal and
the proposed CCS system are not connected actions is both
arbitrary and contrary to law. On remand, the Commission
must consider the actions together in its environmental analysis
before deciding whether to reauthorize the terminal.
2
Even if Rio Grande decides on remand that it does not wish
to proceed with the CCS proposal (thereby mooting the
connected-action issue), the Commission must, at the very

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least, analyze the proposal as an alternative via a supplemental
EIS before reauthorizing the Rio Grande terminal.
NEPA regulations require an agency to “[e]valuate
reasonable alternatives to the proposed action.” 40 C.F.R.
§ 1502.14(a) (2020). As we have already discussed, those
regulations also require an agency to prepare a supplemental
EIS “if a major Federal action remains to occur” and “there are
significant new circumstances or information relevant to
environmental concerns and bearing on the proposed action or
its impacts.” Id. § 1502.9(d)(1)(ii) (2020). Here, petitioners
correctly argue that Rio Grande’s determination that CCS is a
reasonable and feasible alternative to the terminal as proposed
constitutes significant new information under the regulations.
The feasibility of CCS as an alternative “provides a
seriously different picture of the environmental landscape,”
Stand Up, 994 F.3d at 629 (emphasis and quotation omitted),
and “will affect the quality of the human environment . . . to a
significant extent not already considered,” Marsh, 490 U.S. at
374 (alteration and quotation omitted). In its application to the
Commission, Rio Grande represented that its proposed CCS
system would “capture and sequester at least 90%” of the
carbon dioxide produced by the terminal. No. 23-1174 J.A.
714. It also estimated that the system would reduce
conventional air pollution (e.g., sulfur dioxide emissions) by
94.8% and fine particulate matter emissions by 49.2%. See
No. 23-1174 J.A. 683. Indeed, the Commission agreed at oral
argument that had the CCS system been proposed at the same
time as the terminal, the Commission would have been
required, as part of its EIS, to consider inclusion of the system
as a reasonable alternative. See Oral Argument Tr. 36:22–37:6.

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The Commission offers two procedural arguments to
justify its decision to not analyze the CCS proposal as part of
the terminal reauthorization. Both are meritless.
The Commission asserts that res judicata precludes
petitioners’ claim because we already rejected in Vecinos II
petitioners’ challenges to the adequacy of the Commission’s
original analysis of alternatives. See 2021 WL 3716769, at *3.
But that doctrine “does not preclude claims based on facts not
yet in existence at the time of the original action.” Drake v.
FAA, 291 F.3d 59, 66 (D.C. Cir. 2002). Here, the feasibility of
CCS for the terminal first came to light after our remand, when
Rio Grande submitted its proposal to the Commission. See No.
23-1174 Respondent’s Brief 17. Only at that point did
petitioners have the concrete basis to argue that CCS should
have been considered as a viable alternative that would satisfy
the terminal’s purpose while limiting its adverse environmental
impacts.
The Commission also contends that consideration of CCS
as an alternative is outside the scope of our remand in
Vecinos I. True, the scope of our remand would normally
dictate which issues the Commission was required to address.
See Canadian Ass’n of Petrol. Producers v. FERC, 254 F.3d
289, 298 (D.C. Cir. 2001). But in the unusual circumstances
of this case, we cannot credit the Commission’s reliance on the
scope of our remand in Vecinos I. The CCS proposal was not
before us or the Commission when we decided that case.
Instead, as noted above, Rio Grande placed the proposal before
the Commission specifically in response to our remand, which
required the Commission to reassess its ultimate decision to
approve the project. On those unique facts, the Commission
should have considered the CCS alternative as part of the
terminal reauthorization process. See also Marsh, 490 U.S. at
371–72 (indicating the obligation to consider new information

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26
exists so long as the agency retains “a meaningful opportunity”
to weigh project benefits against environmental harms).
C
Next, we turn to petitioners’ arguments that various
aspects of the Commission’s new environmental justice and air
pollution analyses are arbitrary and capricious. Because we
remand for the Commission to issue a supplemental EIS for its
environmental justice analysis, we need not address several of
those arguments. In particular, petitioners argue that the
Commission’s choice of a fifty-kilometer radius was arbitrary;
that it erred by using the NAAQS to analyze whether air quality
impacts were “disproportionate and adverse”; and that it failed
to make a concrete conclusion about whether air quality
impacts were disproportionate and adverse. Given our remand,
we decline to address these challenges to the extant analysis.
There are, however, two challenges to the Commission’s
updated air pollution analysis that are fit for resolution now.
1
Petitioners argue that the Commission erred by relying on
Rio Grande’s air pollution analysis, which used air quality data
only from the Brownsville monitor, and instead should have
also considered data from the Isla Blanca monitor, which is
located closer to the projects than the Brownsville monitor.
This error matters, petitioners say, because the Isla Blanca data
showed potential NAAQS exceedances for fine particulate
matter (PM 2.5 ), while the Brownsville monitor did not. We
agree that the Commission’s explanation for rejecting the Isla
Blanca data is arbitrary and capricious.
The Commission provided two reasons for declining to
examine data from the Isla Blanca monitor. First, the
Commission said that “the Isla Blanca monitor was

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appropriately excluded from the air quality analysis because it
appears that the monitor did not have three years of data . . . as
contemplated by EPA and the Texas Commission on
Environmental Quality” at the “time the analysis was
completed.” No. 23-1175 Rehearing Order ¶ 17 & n.40; see
No. 23-1174 Rehearing Order ¶ 27. But at the time Rio Grande
completed its analysis using the Brownsville data in January
2023, the Isla Blanca monitor did have more than three years
of data. As the Commission itself noted, the Isla Blanca
monitor began collecting “valid design values” on October 7,
2019, which means it had collected about three years and three
months of data by January 2023. No. 23-1174 Rehearing Order
¶ 27; No. 23-1175 Rehearing Order ¶ 17.
On appeal, Rio Grande attempted to bolster the
Commission’s conclusion by explaining that in January 2023
the Isla Blanca monitor did not have three years of validated
and published data. See No. 23-1174 Respondent-Intervenor
Rio Grande Brief 20. But because that explanation is not what
the Commission said in its orders, nor is it an explanation that
can be “reasonably . . . discerned” from what the Commission
did say, we give it no weight. Bowman Transp. Inc. v. Ark.-
Best Freight Sys., Inc., 419 U.S. 281, 286 (1974); see SEC v.
Chenery Corp., 318 U.S. 80, 94 (1943).
Second, the Commission said the Brownsville monitor
was “closer in proximity to environmental justice communities
than the Isla Blanca monitor.” No. 23-1174 Rehearing Order
¶ 27; see No. 23-1175 Rehearing Order ¶ 17. Even if the
Brownsville monitor is closer to more environmental justice
communities, there are also such communities near the Isla
Blanca monitor. The Commission provided no explanation in
its Remand Orders or even at oral argument why it could not
have considered data from both monitors to assess the air
pollution impacts on environmental justice communities,

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especially considering that the Isla Blanca monitor displayed
potential NAAQS exceedances. See Oral Argument Tr. 24:25–
25:3 (Commission stating it could have considered both
monitors’ data).
The Commission’s explanations for rejecting use of the
Isla Blanca monitor are arbitrary and capricious. On remand,
the Commission must either include that data in its analysis or
provide a new, reasoned explanation for declining to do so.
2
Second, petitioners challenge the Commission’s updated
ozone analysis as arbitrary and capricious for failing to
expressly consider the effect on ozone of emissions from the
mobile ships that will export natural gas in connection with the
projects. In Vecinos II, we upheld the Commission’s ozone
analysis even though the EIS’s model did not account for
mobile ship emissions because the Commission considered
such emissions in its 2020 Rehearing Order. See 2021 WL
3716769, at *4.
The Commission was not required on remand to conduct a
new ozone analysis, but because the Commission chose to do
so, we now review its new analysis. See Canadian Ass’n of
Petrol. Producers, 254 F.3d at 298.
The Commission’s updated ozone analysis was not
arbitrary and capricious. The cumulative emissions model the
Commission relied on appears to account for “background
concentrations from mobile ship emissions.” No. 23-1175
Remand Order ¶ 76; No. 23-1174 Remand Order ¶ 137. But
even if the Commission’s cumulative model did not include
mobile ship emissions, such an error would not be prejudicial.
The mobile ship emissions are otherwise in the record and
showed a substantial drop in ozone precursor (NOx) emissions

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compared to the emissions analyzed in the 2020 rehearing
order. Compare No. 23-1174 J.A. 785 (Rio Grande’s updated
NOx total ship emissions is 84.9 tons per year), with No. 23-
1174 J.A. 549 & n.175 (Rio Grande’s NOx total ship emissions
in 2020 rehearing order was 928.7 ton per year). Overall
cumulative ozone emissions also decreased, as expected, due
to the design change from six to five liquefaction trains and
cancellation of the Annova terminal.5 See Vecinos II, 2021 WL
3716769, at *4 n.4 (acknowledging these changes “would
cause less ozone to be produced than the original design would
have”). Because petitioners do not cast doubt on that data and
provide no reason why either mobile ship emissions or
cumulative ozone emissions would increase beyond the levels
previously authorized by the Commission, we hold that the
Commission’s updated ozone analysis was not prejudicially
deficient even if it did not account for mobile ship emissions.
See PDK Labs., Inc. v. DEA, 362 F.3d 786, 799 (D.C. Cir.
2004) (“If the agency’s mistake did not affect the outcome, if
it did not prejudice the petitioner, it would be senseless to
vacate and remand for reconsideration.”).
D
Next, petitioners contend that the Commission failed to
satisfy our remand directive regarding its analysis of GHG
emissions.
In Vecinos I, we instructed the Commission to “explain
whether 40 C.F.R. § 1502.21(c) [(2020)] calls for it to apply
5 The project originally included a third LNG terminal to be
developed by Annova, LLC, which was also authorized by the
Commission and appealed to this Court in Vecinos I. Prior to oral
argument in that case, “Annova, LLC informed the Commission that
it was abandoning its project,” and we dismissed that petition as
moot. 6 F.4th at 1327.

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the social cost of carbon protocol or some other analytical
framework” to evaluate the impact of each project’s
contribution to climate change and “if not, why not.” 6 F.4th
at 1329–30. Section 1502.21(c)(4) states that “[i]f the
information relevant to reasonably foreseeable significant
adverse impacts cannot be obtained because the overall costs
of obtaining it are unreasonable or the means to obtain it are
not known, the agency shall include within the environmental
impact statement . . . [its] evaluation of such impacts based
upon theoretical approaches or research methods generally
accepted in the scientific community.” 40 C.F.R.
§ 1502.21(c)(4) (2020).
Given the scope of our remand on this issue, we need not
(and do not) opine on the overall adequacy of the
Commission’s explanation for why it declined to use the social
cost of carbon protocol to assess the significance of the
projects’ GHG emissions. For purposes of this appeal, it
suffices that the Commission adequately explained why
Section 1502.21(c)(4) does not compel use of the protocol for
that task.
The social cost of carbon is a method of quantifying in
dollars the climate change impacts of greenhouse gas
emissions. See Del. Riverkeeper Network v. FERC, 45 F.4th
104, 111 (D.C. Cir. 2022). Consistent with its position in prior
proceedings, the Commission explained in the Remand Orders
that “there are no criteria to identify what monetized values are
significant for NEPA purposes, and [the Commission is]
currently unable to identify any such appropriate criteria.”
No. 23-1174 Remand Order ¶ 93; No. 23-1175 Remand Order
¶ 20 (same); see also Ctr. for Biological Diversity, 67 F.4th at
1184; EarthReports, 828 F.3d at 956. As a result, the
Commission explained, the social cost of carbon “does not
enable the Commission to determine credibly whether the

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reasonably foreseeable GHG emissions associated with a
project are significant or not significant in terms of their impact
on global climate change.” No. 23-1174 Remand Order ¶ 93;
No. 23-1175 Remand Order ¶ 20 (same). Thus, any attempt to
determine GHG emissions’ significance using the social cost
of carbon protocol would not turn on the application of
“theoretical approaches or research methods generally
accepted in the scientific community.” 40 C.F.R.
§ 1502.21(c)(4) (2020); see No. 23-1174 Remand Order ¶ 92;
No. 23-1175 Remand Order ¶ 20.
Petitioners argue that, because the Commission
consistently exercises its policy judgment to determine the
severity and significance of project impacts on other aspects of
the environment (such as wetlands, recreation, wildlife, and
habitats), it can do the same for GHG emissions. But given the
narrow issue before us, that argument is beside the point. The
question on remand regarding the social cost of carbon protocol
was whether Section 1502.21(c)(4) requires the Commission to
make a significance determination using the protocol, not
whether, as a general matter, the protocol may be used to make
such a determination. As explained above, the Commission
adequately explained why the answer is no.
Petitioners’ other counterarguments fare no better. They
identify examples of other agencies incorporating the social
cost of carbon protocol into their NEPA analyses. See No. 23-
1174 Petitioners’ Brief 54 n.10 (citing environmental impact
statements issued by the Maritime Administration, the Bureau
of Land Management, and the Bureau of Ocean Energy
Management); No. 23-1175 Petitioners’ Brief 48 n.8 (same).
But in none of those examples did the agency use the protocol
to determine GHG emissions’ significance. At most, those
agencies disclosed the social cost of the relevant emissions for
informational purposes, which is exactly what the Commission

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did for each of the projects here. See No. 23-1174 Remand
Order ¶¶ 98–99; No. 23-1175 Remand Order ¶ 24.
Apart from the social cost of carbon, petitioners insist that
the Commission failed to heed our instruction on remand to
also consider whether Section 1502.21(c)(4) required the
application of “some other analytical framework” to determine
GHG significance. See Vecinos I, 6 F.4th at 1329–30.
Specifically, petitioners argue that the Commission “simply
could have made an ad-hoc determination of significance” like
it did in Northern Natural Gas Co., 174 FERC ¶ 61,189 (Mar.
22, 2021). No. 23-1174 Petitioners’ Brief 58; No. 23-1175
Petitioners’ Brief 52 (same). There, the Commission found
that a project’s operations would increase national GHG
emissions by only 0.000006%. N. Nat., 174 FERC ¶ 61,189,
¶ 34. The Commission then concluded that “[h]owever [its]
approach to the significance analysis evolves, the reasonably
foreseeable GHG emissions associated with th[e] project
would not be considered significant.” Id. ¶ 33. Petitioners
argue that the converse is true here and that the Commission
could have applied Northern Natural’s logic to conclude that
the projects’ GHG emissions were significant. They also assert
that other regulations beyond Section 1502.21(c) require the
Commission to “evaluate the significance of greenhouse gas
emissions somehow.” No. 23-1174 Petitioners’ Brief 57 (citing
18 C.F.R. § 380.7(a), (d) and 40 C.F.R. § 1502.16(a)(1)
(2020)); No. 23-1175 Petitioners’ Brief 52 (same). But
petitioners never made any of these specific arguments to the
Commission on rehearing. Because they offer no reasonable
ground for failing to do so, we lack jurisdiction to consider the
arguments on appeal. 15 U.S.C. § 717r(b).
Finally, petitioners advance related arguments that the
Commission failed to explain the role GHG emissions played
in the public interest determinations under NGA Sections 3 and

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7. We considered and dispensed with those arguments in
Vecinos II. 2021 WL 3716769, at *1 (denying the petitions “in
all respects other than those ruled upon in the
contemporaneously issued published opinion”). In Vecinos I,
we remanded the Commission’s NGA determinations only
insofar as the Commission relied on a GHG emissions analysis
that did not grapple with the requirements of 40 C.F.R.
§ 1502.21(c)(4) (2020). See 6 F.4th at 1331. Because, on
remand, the Commission adequately explained why Section
1502.21(c) does not alter its GHG analysis, we see no reason
to question the resulting NGA determinations on GHG
grounds.
III
The deficiencies discussed above warrant vacating the
reauthorization orders for the projects. Although we do not
take this step lightly, the circumstances here require it.
“Vacatur ‘is the normal remedy’ when we are faced with
unsustainable agency action.” Bhd. of Locomotive Eng’rs &
Trainmen v. Fed. R.R. Admin., 972 F.3d 83, 117 (D.C. Cir.
2020) (quoting Allina Health Servs. v. Sebelius, 746 F.3d 1102,
1110 (D.C. Cir. 2014)). We typically assess the decision to
vacate based on two factors: “the seriousness of the order’s
deficiencies (and thus the extent of doubt whether the agency
chose correctly) and the disruptive consequences” of vacatur.
Allied-Signal v. Nuclear Regul. Comm’n, 988 F.2d 146, 150
(D.C. Cir. 1993).
“When an agency bypasses a fundamental procedural
step,” the first factor asks “not whether the ultimate action
could be justified, but whether the agency could, with further
explanation, justify its decision to skip that procedural step.”
Standing Rock Sioux Tribe v. U.S. Army Corps of Eng’rs,
985 F.3d 1032, 1052 (D.C. Cir. 2021). Here, the answer is no.

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For both projects, the Commission failed to issue a
supplemental EIS to account for its updated environmental
justice analysis. And for the Rio Grande terminal, the
Commission further failed to consider the company’s CCS
proposal as part of its environmental review as either a
connected action or a project alternative. For the reasons
detailed above, we do not see how the Commission could
justify its decision to skip those fundamental procedural steps.
We appreciate the significant disruption vacatur may cause
the projects. But that does not outweigh the seriousness of the
Commission’s procedural defects. Cf. Env’t Def. Fund v.
FERC, 2 F.4th 953, 976 (D.C. Cir. 2021) (noting that “the
second Allied-Signal factor is weighty only insofar as the
agency may be able to rehabilitate its rationale” (quotation
omitted)). In any event, even for the likely more substantial
task on remand—consideration of the CCS proposal—Rio
Grande itself stated to the Commission that an assessment
could be done “expeditiously.” No. 23-1174 J.A. 715.
In addition, although we did not vacate the orders in our
prior remand, we have explained that this fact can actually
support vacatur where, as here, the agency “has yet again come
up with insufficient support” for its action. Am. Pub. Gas Ass’n
v. U.S. Dep’t of Energy, 72 F.4th 1324, 1343 (D.C. Cir. 2023)
(quotation omitted).
We therefore grant the petitions for review in part, deny
them in part, vacate both reauthorizations, and remand to the
Commission for further proceedings consistent with this
opinion.
So ordered.

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