United States Court of Appeals 

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued April 4, 2017 Decided May 23, 2017 

No. 16-1092 

DELAWARE RIVERKEEPER NETWORK AND MAYA VAN 

ROSSUM, THE DELAWARE RIVERKEEPER, 

PETITIONERS

v. 

FEDERAL ENERGY REGULATORY COMMISSION, 

RESPONDENT

TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC, 

INTERVENOR

On Petition for Review of Orders of the 

Federal Energy Regulatory Commission 

Aaron Stemplewicz argued the cause and filed the briefs 

for petitioners. 

Holly E. Cafer, Senior Attorney, Federal Energy 

Regulatory Commission, argued the cause for respondent. 

With her on the brief were Robert H. Solomon, Solicitor, and 

Lisa B. Luftig, Attorney. Karin L. Larson, Attorney, Federal 

Energy Regulatory Commission, entered an appearance. 
2 

John F. Stoviak argued the cause for intervenor. With him 

on the brief were Pamela S. Goodwin, Elizabeth U. Witmer, 

and Patrick F. Nugent. 

Before: GARLAND, Chief Judge, GRIFFITH, Circuit Judge, 

and EDWARDS, Senior Circuit Judge. 

EDWARDS, Senior Circuit Judge: This case involves three 

federal statutes: the Natural Gas Act (“NGA”), 15 U.S.C. 

§ 717, et seq.; the Clean Water Act (“CWA”), formally titled 

the Federal Water Pollution Control Act Amendments of 1972, 

33 U.S.C. § 1251, et seq.; and the National Environmental 

Policy Act (“NEPA”), 42 U.S.C. § 4321, et seq. Although the 

Federal Energy Regulatory Commission (“FERC” or 

“Commission”) administers only the NGA, all three statutes 

apply to the disputed actions taken by the Commission in this 

case. 

On September 30, 2013, Transcontinental Gas Pipe Line 

Company, LLC (“Transco”) filed an application with FERC to 

construct and operate its proposed Leidy Southeast Project 

(“Leidy Project”). The project was designed to expand the 

capacity of Transco’s existing natural gas pipeline and add new

facilities in Pennsylvania and New Jersey. Pursuant to the 

requirements of NEPA, FERC conducted an environmental 

review of the project and issued an environmental assessment 

(“EA”) on August 11, 2014. The EA found, with appropriate 

mitigating measures, “no significant impacts” associated with 

the Leidy Project. However, it required Transco to obtain “all 

applicable authorizations required under federal law” prior to 

FERC authorizing construction. Because it was understood that 

the Leidy Project might result in discharges into navigable 

waters, Transco was obligated by § 401 of the CWA to obtain 

a water quality certification from the state in which the 

discharge would originate before FERC could authorize any 
3 

activity that “may result” in such a discharge. See 33 U.S.C. 

§ 1341(a)(1). The EA thus in turn required Transco to obtain 

this state certification before FERC would authorize any 

construction. 

On June 10, 2014, Transco applied for a § 401 certification 

from Pennsylvania’s Department of Environmental Protection. 

On December 18, 2014, before Pennsylvania had acted on 

Transco’s application, FERC issued a Certificate of Public 

Convenience and Necessity (“Certificate Order”) under the 

NGA conditionally approving the Leidy Project. The 

Certificate Order made it clear that FERC would not authorize 

any construction until Transco had obtained a § 401 

certification from Pennsylvania. Delaware Riverkeeper 

Network, a nonprofit organization, timely sought rehearing of 

the Certificate Order before the Commission. FERC denied the 

request for rehearing. Delaware Riverkeeper Network and 

Maya van Rossum, the current Delaware Riverkeeper (together 

“Riverkeeper”), then petitioned for review in this court. 

Transco intervened in support of the Commission. 

Before this court, Riverkeeper contends that the 

Commission violated the CWA because it granted Transco’s 

request to construct and operate the Leidy Project prior to the

issuance of Pennsylvania’s § 401 water quality certification. 

Riverkeeper also claims that the Commission violated NEPA 

in failing to establish an accurate baseline from which to 

conduct its environmental review of the Leidy Project. In 

particular, Riverkeeper argues that FERC misidentified 

numerous specially protected wetlands, and miscalculated both 

the cover type categorization of those wetlands and the total 

acreage of those wetlands. We find no merit in these claims 

and, therefore, reject the petition for review.
4 

I. BACKGROUND

A. Statutory Background 

 Under the NGA, a natural gas pipeline company must 

obtain a Certificate of Public Convenience and Necessity from 

FERC prior to “undertak[ing] the construction or extension” of 

any natural gas facility for the transportation of natural gas in 

interstate commerce. 15 U.S.C. § 717f(c)(1)(A). FERC may 

place any reasonable conditions on the issuance of such a 

certificate “as the public convenience and necessity may 

require.” Id. § 717f(e). This court has jurisdiction to review 

challenges to certificates granted under the NGA, but 

petitioning parties must first seek rehearing before the 

Commission and may not raise any argument before this court 

that was not raised on rehearing. See 15 U.S.C. § 717r(b). 

Letter orders issued by FERC are also subject to review in this

court subject to the same rehearing requirement. See 18 C.F.R. 

§ 385.1902. 

 In addition to the requirements of the NGA, § 401 of the 

CWA requires “[a]ny applicant for a Federal license or permit 

to conduct any activity including . . . the construction or 

operation of facilities, which may result in any discharge into

the navigable waters,” to “provide the licensing or permitting 

agency a certification from the State in which the discharge 

originates or will originate.” 33 U.S.C. § 1341(a)(1). The state 

must certify “that any such discharge will comply” with the 

CWA’s effluent limitations and other pollutant control 

requirements, including state-administered water quality 

standards. Id. The state may certify that there are no applicable 

limitations or standards for the discharge activity, or it may 

deny certification or waive the certification requirement. Id.

But “[n]o license or permit shall be granted until the 

certification . . . has been obtained or has been waived.” Id. Any 
5 

limitation in a § 401 certification “shall become a condition” of 

the federal license or permit requiring such certification. Id. 

§ 1341(d). 

 Section 401 is an important part of the CWA, in which 

“Congress sought to expand federal oversight of projects 

affecting water quality while also reinforcing the role of States 

as the prime bulwark in the effort to abate water pollution.” 

Alcoa Power Generating Inc. v. FERC, 643 F.3d 963, 971 

(D.C. Cir. 2011) (citation and internal quotation marks 

omitted). The state certification authority under § 401 is “‘[o]ne 

of the primary mechanisms’ through which [states] may 

exercise this role, as it provides them with ‘the power to block, 

for environmental reasons, local water projects that might 

otherwise win federal approval.’” Id. (quoting Keating v. 

FERC, 927 F.2d 616, 622 (D.C. Cir. 1991)). 

 The last statute at issue in this case is NEPA, which was 

enacted in part to “promote efforts which will prevent or 

eliminate damage to the environment and biosphere . . . [and] 

enrich the understanding of the ecological systems and natural 

resources important to the Nation.” 42 U.S.C. § 4321. As we 

recently explained: 

The Commission, in exercising its . . . authority, 

must comply with NEPA and its implementing 

regulations, which require that all federal agencies 

include an environmental impact statement (“EIS”) 

“in every recommendation or report on . . . major 

Federal actions significantly affecting the quality of 

the human environment.” 42 U.S.C. § 4332(2)(C); see 

also 40 C.F.R. § 1508.11. To determine whether an 

EIS is necessary, an agency first prepares an 

environmental assessment, 40 C.F.R. § 1508.9, which 

must include, among other information, a discussion 
6 

of “the environmental impacts of the proposed 

action,” id. § 1508.9(b). “Indirect effects . . . are 

caused by the action and are later in time or farther 

removed in distance, but are still reasonably 

foreseeable.” Id. § 1508.8(b). “Cumulative impact is 

the impact on the environment which results from the 

incremental impact of the action when added to other 

past, present, and reasonably foreseeable future 

actions regardless of what agency (Federal or nonFederal) or person undertakes such other actions.” Id. 

§ 1508.7; see also id. § 1508.8. After preparing an 

environmental assessment, an agency may conclude 

that the proposed action would have no significant 

impact (often referred to as a “FONSI,” for “finding 

of no significant impact”) in lieu of issuing an EIS. Id.

§§ 1508.9(a)(1), 1508.13. 

Sierra Club v. FERC, 827 F.3d 59, 63 (D.C. Cir. 2016). For 

either an EA or an EIS, the purposes of NEPA require the 

Commission to “consider and disclose” the environmental 

effects of the actions it certifies. Balt. Gas & Elec. Co. v. Nat. 

Res. Def. Council, Inc., 462 U.S. 87, 96 (1983). So long as the 

agency takes a hard look at the environmental consequences, 

NEPA “does not mandate particular results.” Robertson v. 

Methow Valley Citizens Council, 490 U.S. 332, 350 (1989). 

B. Factual and Procedural Background 

 Transco maintains an interstate natural gas pipeline that 

runs from Texas to New York City, passing through 

Pennsylvania. In September 2013, Transco applied to FERC 

for a Certificate of Public Convenience and Necessity for the 

Leidy Project, which would add approximately thirty miles of 

looping to Transco’s existing pipeline in Luzerne and Monroe 

Counties, Pennsylvania and parts of New Jersey, to meet 
7 

increasing energy demands. On August 11, 2014, FERC issued 

a finding of no significant impact and published its review of 

the environmental consequences of the Leidy Project in a 217-

page EA. Environmental Assessment, Joint Appendix (“JA”) 

168–331. Among a number of conditions, Environmental 

Condition No. 9 of the EA required Transco to obtain and file 

with the Secretary of the Commission “all applicable 

authorizations required under federal law (or evidence of 

waiver thereof)” prior to FERC authorizing construction. Id. at 

324. The EA identified § 401 state water quality certifications

as required authorizations. The EA also discussed mitigation 

for the Leidy Project’s impact on Pennsylvania wetlands and 

concluded that the project’s proposed pipeline gas flow 

velocities were safe. 

 Transco had timely applied for a § 401 certification from 

Pennsylvania’s Department of Environmental Protection on 

June 10, 2014. However, on December 18, 2014, FERC issued 

a Certificate Order to Transco, conditionally approving the 

Leidy Project, before Pennsylvania had acted on Transco’s 

§ 401 request. The Certificate Order adopted the conditions of 

the EA, including Environmental Condition No. 9, which 

clearly stated that Transco was required to obtain all applicable 

federal authorizations, including a § 401 certification from 

Pennsylvania. FERC was thus clear that it would not authorize 

any construction before the necessary § 401 certifications had 

been obtained. On January 16, 2015, Riverkeeper sought 

rehearing of the Certificate Order before the Commission. 

 During the early months of 2015, after the conditional 

Certificate Order had been issued, the Commission authorized 

Transco via letter orders to conduct certain “pre-construction”

activities, including tree-felling. Riverkeeper moved the 

Commission to stay the tree-felling activity. FERC denied this 

request. Riverkeeper never sought rehearing of this action or of 
8 

any of FERC’s letter orders. Instead, on March 15, 2015, 

Riverkeeper filed a petition for an emergency stay with this 

court. The Petition was denied on March 19, 2015. Del. 

Riverkeeper Network v. FERC, No. 15-1052 (D.C. Cir. Mar. 

19, 2015), ECF No. 1543345. By the end of March 2015, 

Transco had begun felling trees, as authorized, along a rightof-way by the projected pipelines, including in Pennsylvania 

wetlands. 

 

 On April 6, 2015, Pennsylvania’s Department of 

Environmental Protection issued a § 401 certification for the 

Leidy Project. Riverkeeper challenged the Pennsylvania 

certification by filing a petition for review in the Third Circuit, 

but the petition was denied. Del. Riverkeeper Network v. Sec’y 

Penn. Dep’t of Envtl. Prot., 833 F.3d 360, 385–88 (3d Cir. 

2016) (upholding Pennsylvania’s decision to issue the § 401 

certification). 

 On March 3, 2016, FERC denied Riverkeeper’s request for 

rehearing. Riverkeeper timely petitioned this court for review 

of FERC’s EA, Certificate Order, and order denying rehearing. 

Transco intervened. 

II. ANALYSIS

A. Standard of Review 

“[I]n evaluating the Commission’s authority to issue [a] 

challenged certificate of public convenience and necessity[,] 

[w]e . . . review[] the Commission’s interpretation of its 

authority to issue such a certificate by applying the two-step 

analytical framework of Chevron.” Myersville Citizens for a 

Rural Cmty., Inc. v. FERC, 783 F.3d 1301, 1315 (D.C. Cir. 

2015) (citing Chevron, U.S.A. Inc. v. Nat. Res. Def. Council, 

467 U.S. 837 (1984)). Under the Chevron framework, 
9 

an agency’s power to regulate “is limited to the scope 

of the authority Congress has delegated to it.” Am. 

Library Ass’n v. FCC, 406 F.3d 689, 698 (D.C. Cir. 

2005). Pursuant to Chevron Step One, if the intent of 

Congress is clear, the reviewing court must give effect 

to that unambiguously expressed intent. If Congress 

has not directly addressed the precise question at issue, 

the reviewing court proceeds to Chevron Step Two. 

Under Step Two, “[i]f Congress has explicitly left a 

gap for the agency to fill, there is an express delegation 

of authority to the agency to elucidate a specific 

provision of the statute by regulation. Such legislative 

regulations are given controlling weight unless they are 

. . . manifestly contrary to the statute.” Chevron, 467 

U.S. at 843–44. Where a “legislative delegation to an 

agency on a particular question is implicit rather than 

explicit,” the reviewing court must uphold any 

“reasonable interpretation made by the administrator 

of [that] agency.” Id. at 844. But deference to an 

agency’s interpretation of its enabling statute “is due 

only when the agency acts pursuant to delegated 

authority.” Am. Library Ass’n, 406 F.3d at 699. 

EDWARDS, ELLIOTT, & LEVY, FEDERAL STANDARDS OF 

REVIEW 166–67 (2d ed. 2013). 

A court does not defer to an agency’s interpretation of a 

statute that it is not charged with administering. See Metro. 

Stevedore Co. v. Rambo, 521 U.S. 121, 138 n.9 (1997). 

Therefore, we do not accord Chevron deference to the 

Commission’s interpretation of the CWA because the 

Environmental Protection Agency, not FERC, administers the 

statute. See Alcoa Power, 643 F.3d at 972. Our review of the 

requirements of the CWA is de novo. Id.
10 

 Finally, we apply “a ‘rule of reason’ to an agency’s NEPA 

analysis and ha[ve] repeatedly refused to ‘flyspeck’ the 

agency’s findings in search of ‘any deficiency no matter how 

minor.’” Myersville, 783 F.3d at 1322–23 (citations omitted). 

Because “NEPA’s requirements are ‘essentially procedural,’” 

so “long as the agency’s decision is ‘fully informed’ and ‘wellconsidered,’ it is entitled to judicial deference.” Nat. Res. Def. 

Council v. Hodel, 865 F.2d 288, 294 (D.C. Cir. 1988) (citations 

omitted). Especially “[w]hen considering FERC’s evaluation 

of ‘scientific data within its technical expertise,’ we afford 

FERC ‘an extreme degree of deference.’” Myersville, 783 F.3d 

at 1308 (citation omitted). 

B. Jurisdiction 

FERC argues that Riverkeeper’s Clean Water Act claim 

“may no longer present an ongoing case or controversy” as “[i]t

is not clear what relief would be available to remedy 

Riverkeeper’s sequencing claims—if they prevailed—where 

the [state] water quality certifications have been issued and 

affirmed on appeal [by the Third Circuit].” Br. for FERC at 22 

n.3. In other words, according to FERC, even if the agency 

issued the conditional Certificate Order prematurely, no 

remedy is needed for the sequencing error because the state 

water quality certifications have been issued and found lawful.

FERC’s argument is misguided. 

First, the principal issue before the Third Circuit was 

whether Pennsylvania “was required to engage in an 

environmental review prior to issuing a Water Quality 

Certification.” Del. Riverkeeper, 833 F.3d at 385. Here, in 

contrast, the question raised by Riverkeeper is whether the 

Commission (not Pennsylvania) violated the sequencing 

requirement of the CWA by issuing its Certificate Order before 

Pennsylvania issued its § 401 certification. These are entirely
11 

distinct issues and the former does not subsume the latter. 

FERC does not argue otherwise. 

Furthermore, Riverkeeper’s claim is not moot because 

once the CWA’s sequence has been flouted, the only fix is to 

start the process over. Riverkeeper asks this court to “rescind[] 

the Commission’s Orders, or remand[] the decision to ensure 

that the Orders comply with the [Clean Water Act] and NEPA.” 

Br. for Pet’rs at 15. We could provide Riverkeeper the remedy 

it seeks by rescinding the conditional Certificate Order. That 

would halt the project and force FERC to follow the proper 

sequence of action. See Gunpowder Riverkeeper v. FERC, 807 

F.3d 267, 272 (D.C. Cir. 2015) (rejecting similar mootness 

argument because granting relief on the NEPA claim would 

undo the conditional certificate, which could start the CWA 

sequence over). 

Perhaps FERC means to suggest that no effectual relief can 

be granted because vacating the Certificate Order and 

remanding the matter to the agency would almost certainly 

have no real world consequences. In other words, in FERC’s 

view, even if the court were to remand the case, the agency 

could immediately re-issue the conditional Certificate Order 

because the state water quality certifications have been issued. 

Such a response by FERC is not unlikely, but it is surely not 

guaranteed. In any event, “[c]ourts often adjudicate disputes 

where the practical impact of any decision is not assured.” 

Chafin v. Chafin, 568 U.S. 165, 133 S. Ct. 1017, 1025 (2013). 

Therefore, we could grant Riverkeeper vacatur of FERC’s 

conditional Certificate Order even if its victory might be short 

lived. “Such relief would of course not be ‘fully satisfactory,’ 

but with respect to the case as whole, ‘even the availability of 

a partial remedy is sufficient to prevent [a] case from being 

moot.’” Id. at 1026 (quoting Calderon v. Moore, 518 U.S. 149, 

150 (1996) (per curiam)). 
12 

In sum, we agree with Riverkeeper that we have 

jurisdiction to consider its challenge to the Certificate Order on 

the ground that FERC violated the sequencing requirement of 

the CWA by issuing its Certificate Order before Pennsylvania 

issued its § 401 certification. We therefore proceed to the 

merits of Riverkeeper’s claims under both the CWA and 

NEPA. 

C. Riverkeeper’s Challenges Under the CWA 

Riverkeeper argues that the Commission violated § 401 of 

the CWA by “issu[ing] its approval of the [Leidy] Project prior

to Pennsylvania’s issuance of its Clean Water Act Section 401 

water quality certificat[ion].” Br. for Pet’rs at 19. We disagree. 

We hold that the sequencing requirement of § 401 was not 

triggered because the Commission’s conditional approval of 

the Leidy Project construction did not authorize any activity 

which might result in a discharge in navigable waters. 

We decline to review Riverkeeper’s alternative CWA 

challenge to the letter orders approving pre-construction treefelling. The NGA requires that, prior to challenging an order 

before this Court on review, a party first must file a petition for 

rehearing with the Commission and then specify the challenged 

orders in a petition for judicial review. 15 U.S.C. §§ 717r(a),

(b). Because Riverkeeper failed to seek rehearing of any of the

disputed letter orders authorizing pre-construction activities,

those individual decisions are not properly before this court. 
13 

1. The Sequencing of the Certificate Order and the 

§ 401 Certification 

Section 401 of the CWA requires that “[a]ny applicant for 

a Federal license or permit to conduct any activity . . . which

may result in any discharge into the navigable waters” must 

first obtain a water quality certification from the state in which 

the discharge will originate, and that “[n]o license or permit 

shall be granted until the certification required by this section 

has been obtained or has been waived.” 33 U.S.C. § 1341(a)(1). 

Transco argues preliminarily that the Commission’s 

Certificate Order is not a “license or permit” subject to the 

CWA because it is a “certificate[] of public convenience and 

necessity.” Br. for Transco at 16; see id. at 15–19. We reject 

this argument out of hand. The Commission agrees with 

Riverkeeper that its Certificate Order was a “license or permit” 

potentially subject to the requirements of § 401. Furthermore, 

Transco’s assertion comes too late: before the Commission, 

Transco never claimed that § 401 was inapplicable and the 

company applied to Pennsylvania for the certification without 

protest. Finally, it is clear that Congress intended § 401 to apply 

broadly to federal approval of potential pollution activity. 

The Supreme Court has noted that: 

State certifications under § 401 are essential in the 

scheme to preserve state authority to address the broad 

range of pollution, as Senator Muskie explained on the 

floor when what is now § 401 was first proposed: 

“No polluter will be able to hide behind a Federal 

license or permit as an excuse for a violation of 

water quality standard[s]. No polluter will be able 

to make major investments in facilities under a 
14 

Federal license or permit without providing 

assurance that the facility will comply with water 

quality standards. No State water pollution 

control agency will be confronted with a fait 

accompli by an industry that has built a plant 

without consideration of water quality 

requirements.” 116 Cong. Rec. 8984 (1970). 

These are the very reasons that Congress provided the 

States with power to enforce “any other appropriate 

requirement of State law,” 33 U.S.C. § 1341(d), by 

imposing conditions on federal licenses for activities 

that may result in a discharge, ibid.

S.D. Warren Co. v. Me. Bd. of Envtl. Prot., 547 U.S. 370, 386 

(2006). 

The CWA in its entirety “provides for a system that 

respects the States’ concerns” in application to all federal 

agencies. Id. And the act of “licensing” or “permitting” clearly 

extends to “certifying,” which is merely a different name for 

the stamp of federal approval Congress intended to capture. 

Transco’s reliance on the doctrine of expressio unius, that 

Congress’s selection of “license or permit” excludes a 

“certificate,” is misplaced because that doctrine applies “only

when ‘circumstances support[] a sensible inference that the 

term left out must have been meant to be excluded.’” NLRB v. 

SW Gen., Inc., 137 S. Ct. 929, 933 (2017) (citation omitted). 

Here, the broad sweep of the statute raises no such inference. 

The principal issue here is not whether FERC’s disputed 

Certificate Order is a “license or permit” covered by the CWA, 

but whether it approved “activity . . . which may result in any

discharge” and thus triggered the requirements of the CWA. 33 

U.S.C. § 1341(a)(1). We have previously stated that the 
15 

“logically antecedent” question under § 401 is whether the 

disputed federal permit or license “is subject to the provisions 

of Section 401(a)(1)” in the first place. North Carolina v. 

FERC, 112 F.3d 1175, 1186 (D.C. Cir. 1997). If the activity 

that FERC approved would not result in a discharge, then the 

sequencing requirement of § 401 was not “trigger[ed].” See id.

at 1188. 

Here, the record indicates that the Certificate Order did not 

authorize any activity that could result in a discharge. Instead, 

the conditional Certificate Order was merely a first step for 

Transco to take in the complex procedure to actually obtaining 

construction approval. Br. for FERC at 25–28. And, as 

explained above, FERC required Transco to obtain the 

appropriate state agency permits, including a § 401 

certification from Pennsylvania, prior to FERC granting 

Transco permission to proceed with activity that could result in 

a discharge. 

Judge Rogers’ concurring statement in Gunpowder 

Riverkeeper, which we adopt, disposes of Riverkeeper’s claim 

in this case: 

The plain text of the Clean Water Act does not appear 

to prohibit the kind of conditional certificate the 

Commission issued here. On its face, section 

401(a)(1) does not prohibit all “license[s] or 

permit[s]” issued without state certification, only 

those that allow the licensee or permittee “to conduct 

any activity . . . which may result in any discharge into 

the navigable waters.” 33 U.S.C. § 1341(a)(1). 

Petitioner has pointed to no activities authorized by 

the conditional certificate itself that may result in such 

discharge prior to the state approval and the 

Commission’s issuance of a Notice to Proceed. 
16 

807 F.3d at 279 (Rogers, J., dissenting in part and concurring 

in the judgment) (second emphasis added); see also Myersville, 

783 F.3d at 1320–21 (upholding FERC’s conditional approval 

of a natural gas facility construction project where FERC 

conditioned its approval on the applicant securing a required 

federal Clean Air Act air quality permit from the state); Del. 

Dep’t. of Nat. Res. & Envtl. Control v. FERC, 558 F.3d 575, 

578–79 (D.C. Cir. 2009) (holding Delaware suffered no 

concrete injury from FERC’s conditional approval of a natural 

gas terminal construction despite statutes requiring states’ prior 

approval because FERC conditioned its approval of 

construction on the states’ prior approval). 

Because the Certificate Order expressly conditioned 

FERC’s approval of potential discharge activity on Transco 

first obtaining the requisite § 401 certification, and was not 

itself authorization of any potential discharge activity, the 

issuance of the Certificate Order before Pennsylvania’s 

issuance of its § 401 certificate did not violate § 401 of the 

CWA. 

2. The Letter Orders 

Riverkeeper alternatively contends that the Commission’s 

letter orders authorizing pre-construction tree-felling 

impermissibly approved activity that might have resulted in a 

proscribed discharge before Pennsylvania could issue its water 

quality certification. In response, the Commission contends 

that its letter orders did not trigger the requirements of § 401 

because the U.S. Army Corps of Engineers determined that 

Transco’s “proposed tree cutting activities would not result in

a discharge,” JA 638, and FERC relied on the Corps’ 

determination, JA 644–45. We need not decide this issue, 

however, because Riverkeeper did not independently challenge 

the letter orders. Neither FERC nor Riverkeeper dispute that 
17 

the letter orders reflected final agency action and were 

separately appealable after rehearing before the Commission. 

See 18 C.F.R. § 385.1902(a)–(b). But as it conceded at oral 

argument and in its briefing, Reply Br. for Pet’rs at 3–5, 

Riverkeeper did not request rehearing of the letter orders, so 

the letters are not properly before us for review. See 15 U.S.C. 

§ 717r(a)–(b); see also Darby v. Cisneros, 509 U.S. 137, 145 

(1993) (recognizing the statutory rehearing requirement of 

§ 717r as mandatory). 

In sum, we need not decide whether the letter orders 

impermissibly approved activity that might have resulted in a 

discharge before Pennsylvania issued its § 401 certification. 

D. The Commission’s Wetlands Analysis 

Riverkeeper contends that FERC violated NEPA by 

misclassifying wetlands in two ways: (1) under Pennsylvania’s 

own state classification system; and (2) under the “Cowardin” 

classification system. We reject both challenges. FERC did not 

purport to rely on Pennsylvania’s classification system and 

Riverkeeper does not show how any misclassification under the 

Cowardin system was prejudicial error. 

 Nowhere in the EA does FERC even discuss, much less 

rely on, the application of Pennsylvania’s system. In Appendix 

I, the EA includes a secondary reference to wetlands as either 

“exceptional” or “other,” which is pursuant to the Pennsylvania

Administrative Code. 25 Penn. Admin. Code § 105.17. See JA 

330–31. But the wetlands discussion in the EA itself does not 

use the terms “exceptional” or “other,” and does not refer to the 

Pennsylvania system at all. 

As Riverkeeper concedes, FERC was not bound to use 

Pennsylvania’s classification system. And the EA clearly 
18 

explains that the “field delineations of wetlands” in 

Pennsylvania were performed according to the U.S. Army 

Corps of Engineers’ “Wetlands Delineation Manual (COE, 

1987),” JA 202, and that delineated wetlands “were classified 

as described in Cowardin, et al., (1979),” JA 203. The EA thus 

classifies the wetlands as either Palustrine Forested, Palustrine 

Scrub-Shrub, or Palustrine Emergent wetlands. These three 

Palustrine wetland types are consistent with the Cowardin 

classification system referenced in the Corps’ delineation 

manual. See U.S. ARMY CORPS OF ENG’RS, WETLANDS 

DELINEATION MANUAL 3 (1987); LEWIS M. COWARDIN, ET AL.,

CLASSIFICATION OF WETLANDS AND DEEPWATER HABITATS OF 

THE UNITED STATES 10–13 (1979). 

On rehearing, FERC again rejected Riverkeeper’s 

contention that the agency had used Pennsylvania’s system: 

“As indicated in the EA and the December 18 [Certificate] 

Order, Transco’s wetlands delineations were conducted using 

the Corps’ Wetlands Delineation Manual.” JA 716. Moreover, 

FERC made it clear that each state was to oversee its own 

delineation, clearly implying this was to be done for purposes 

of classification: “It is at the discretion of the Corps [and] the 

Pennsylvania Department of Environmental Protection . . . to 

determine whether Transco’s wetland delineations comply 

with each agency’s permit application process, prior to issuing

the appropriate water quality permit.” JA 514; see also JA 203 

(using “delineate[]” in reference to identifying cover types). 

There is no evidence the secondary wetlands identifications in 

Appendix I as “exceptional” or “other,” even if erroneous, had 

any effect on FERC’s consideration of the environmental 

impact of the Leidy Project. Accordingly, there is no NEPA 

violation here. 

 Riverkeeper’s second wetlands argument attacks the 

Cowardin classification system that the Commission actually 
19 

used. Riverkeeper contends that FERC “failed to accurately 

account for the expected ground disturbance impacts that will 

result from the [Leidy] Project’s construction and operational 

activity,” Br. for Pet’rs at 44, because it misidentified the cover 

types of fourteen wetlands – totaling approximately 3.8 acres 

that would be impacted by operation or construction – pursuant 

to the Cowardin system, see id. at 44–49. For example, 

Riverkeeper argues that aerial photographs show that a wetland 

classified as Palustrine Emergent (non-forested) was “clearly” 

forested and therefore should have been classified as Palustrine 

Forested. Id. at 46. However, Riverkeeper does not explain 

how this inexorably leads to the conclusion that FERC failed 

to accurately account for the Leidy Project’s impact on the 

environment. Indeed, the ultimate implication Riverkeeper 

raises for this alleged erroneous classification is an “alteration 

of wetland value due to vegetation clearing.” Id. at 45 (quoting 

JA 205). But the EA identifies only one difference in 

vegetation clearing: the time it takes for the three different 

types of wetlands to re-vegetate. See JA 205. Riverkeeper does 

not raise any unaccounted-for consequences of this. In other 

words, even assuming FERC misclassified a small area of 

Pennsylvania wetlands, this merely means the Leidy Project 

will result in a longer re-vegetation process for some wetlands, 

and a shorter re-vegetation process for others. Riverkeeper fails 

to explain how this caused FERC’s mitigation plan to be 

significantly deficient. 

What we see from the record in this case is that FERC 

responsibly addressed Riverkeeper’s misclassification 

argument in its Certificate Order. The Commission stated that 

it relied on its classification only to “disclose and evaluate 

potential impacts on wetlands and to serve as a starting point 

for the development of protective mitigation.” JA 514. FERC 

thus disclosed its methodology and purpose as a starting point 

for mitigation, which would subsequently involve the Corps 
20 

and state agencies to further oversee mitigation. See id.; JA 

716–17 (order denying rehearing). It seems clear here that 

FERC took the requisite “hard look” at the impact of the Leidy 

Project on the environment. Hodel, 865 F.2d at 294 (quoting 

Izaak Walton League of America v. Marsh, 655 F.2d 346, 371 

(D.C. Cir. 1981)). Even if FERC technically erred in some of 

its classifications, Riverkeeper has not shown any prejudice by

virtue of the agency “fail[ing] to comply precisely with NEPA 

procedures.” Nevada v. Dep’t of Energy, 457 F.3d 78, 90 (D.C. 

Cir. 2006); see also Hodel, 865 F.2d at 295–97 (refusing to 

remand despite an agency error because it had “serve[d] 

NEPA’s informational function”). 

E. The Commission’s Gas Flow Velocity Analysis 

In its final challenge, Riverkeeper contends that FERC 

“repeatedly failed to disclose information addressing both the 

safety and independent viability” of the Leidy Project’s 

projected pipeline gas flow velocities. Br. for Pet’rs at 57. This 

argument rests on Riverkeeper’s claims that FERC failed to 

consider and disclose (1) key information about Transco’s 

projected gas flow velocities, (2) the project’s interdependence 

on past or future pipeline projects, and (3) the safety risks of its 

gas flow velocities. Id. at 50–60. Riverkeeper also contends 

that FERC treated the Leidy Project differently than a similarly 

situated project. We find no merit in these claims. 

First, the record belies Riverkeeper’s claim that FERC 

withheld critical information regarding the projected gas flow 

velocities. Riverkeeper asserts that it never received answers to 

nine questions it asked, regarding, inter alia, data about the 

pipe diameter, grade, wall thickness, and gas flow rates and 

pressures. Id. at 54–55. The record shows, however, that FERC 

and Transco responded to Riverkeeper’s queries and made it 

clear that the flow diagrams contained in Exhibits G and G-II 
21 

answered the questions that had been raised. JA 159. On 

appeal, Riverkeeper summarily asserts that the cited exhibits 

were non-responsive to its questions, but it does not explain 

how so. 

In fact, the record before us shows that Riverkeeper was 

invited to view Transco’s hydraulic flow modeling software, 

used to project gas flow velocity, via video conference or in 

person (due to the software’s proprietary nature). Riverkeeper 

concedes that this offer was made but asserts it “made the 

decision” to “not waste . . . limited time and resources to fly

their expert from Washington to Texas” to view the software. 

Reply Br. for Pet’rs at 24–25. This is hardly a compelling 

response, especially since Riverkeeper could have viewed the 

modeling software via video conferencing. 

In sum, on the record before us, we have no basis upon 

which to credit Riverkeeper’s vague and unsubstantiated 

assertions that FERC withheld key data from the public. 

Indeed, the record reflects that FERC made every effort to 

comply with requests for information and no information was 

withheld from Riverkeeper. 

Second, Riverkeeper contends that the EA’s data on the 

projected gas flow velocity was insufficient and, therefore, it

could not review the dependence of the Leidy Project on future 

pipeline expansions. Riverkeeper says the information is 

important because FERC’s regulations require the agency to 

review connected, cumulative, or similar actions. See 40 C.F.R. 

§ 1508.25(a); Del. Riverkeeper Network v. FERC, 753 F.3d 

1304, 1309 (D.C. Cir. 2014). In support of this claim, 

Riverkeeper points to this court’s decision in Delaware 

Riverkeeper Network. That case is plainly distinguishable, 

however. There, the court determined that FERC had 

impermissibly segmented NEPA review by approving one of 
22 

four “indisputably related and significantly ‘connected’” 

pipeline upgrade projects without looking at the projects’ 

cumulative impact. Id. at 1313–14. Here, in contrast, FERC 

evaluated the cumulative impact of recent related projects, see

JA 320, and found that “[t]he location of any future expansion 

facilities is entirely speculative.” JA 499. Riverkeeper offers no 

evidence to the contrary. 

Third, Riverkeeper alleges that it presented expert evidence 

to FERC that Transco’s proposed gas flow velocities were 

potentially unsafe, and these concerns were left “wholly 

unanswered and unrebutted.” Br. for Pet’rs at 57. The record 

indicates otherwise. The EA concluded that Transco’s 

proposed gas flow velocities, not to exceed 60-61 feet per 

second, were safe based on an American Petroleum Institute 

report that gave a conservative guideline for maximum flow 

velocity as 100 feet per second for pipelines exposed to liquid

droplet erosion. The Commission concluded that Transco’s 60-

61 feet per second maximum flow velocity was safe, especially 

since Transco’s pipelines would not be subject to liquid 

droplets. JA 498. In both instances, FERC highlighted the fact 

that Riverkeeper did not “cite any industry or government 

standard, regulation, or study to support its position” when 

expressing its concern that gas flow velocities beyond 50 feet 

per second would be unsafe. JA 315; see JA 496. We therefore 

reject Riverkeeper’s claims, which are based on sheer 

speculation, that FERC erred in its determinations regarding 

the safety of the Leidy Project’s gas flow velocities. 

Finally, we reject Riverkeeper’s contention that FERC 

treated similarly situated parties differently and, therefore, the 

agency’s determinations on gas flow velocity are arbitrary and 

capricious. Br. for Pet’rs at 57–60. In 2011, FERC determined 

that a pipeline project, the Northeast Upgrade Project, was not

hydraulically feasible because its gas flow velocity would 
23 

exceed 40 feet per second. Riverkeeper thus asserts that 

FERC’s approval of the Leidy Project’s gas flow velocity of 60 

feet per second is unjustified. The two projects are quite 

different, however. The Northeast Upgrade Project proposed 

adding compression to an existing 24-inch diameter pipeline, 

without adding additional looping. See Br. for FERC at 44. In 

contrast, the Leidy Project proposed to add looping of 42-inch 

diameter pipeline, nearly double that of the Northeast Upgrade 

Project. Riverkeeper is conspicuously silent as to these salient 

differences. 

The Commission’s NEPA review of the Leidy Project’s 

proposed gas flow velocities appears to be fully informed and 

well-considered. Riverkeeper presents no countervailing 

evidence. As such, the Commission’s judgment is “entitled to 

judicial deference.” Hodel, 865 F.2d at 294. 

III. CONCLUSION

For the foregoing reasons, we deny the petition for review. 

 So ordered.