United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued September 26, 2014 Decided May 1, 2015

AmendedJuly21,2015

No. 13-1093

DELAWARE DEPARTMENT OF NATURAL RESOURCES AND

ENVIRONMENTAL CONTROL,

PETITIONER

v.

ENVIRONMENTAL PROTECTION AGENCY,

RESPONDENT

ELECTRIC POWER SUPPLY ASSOCIATION, ET AL.,

INTERVENORS

Consolidated with 13-1102, 13-1104

On Petitions for Review of A Final Rule Promulgated 

by the United States Environmental Protection Agency

David W. DeBruin argued the cause for petitioners PSEG

Power LLC, et al. With him on the briefs were Matthew E.

Price, Elizabeth C. Bullock, Shanna M. Cleveland, and Caitlin

S. Peale.

Valerie Satterfield Edge, Deputy Attorney General, Office

of the Attorney General for the State of Delaware, argued the
2

cause and filed the briefs for petitioner Delaware Department of

Natural Resources and Environmental Control.

Ashley C. Parrish, Karen Schoen, David G. Tewksbury, and

Stephanie S. Lim were on the brief for intervenor Electric Power

Supply Association in support of petitioners. 

Austin D. Saylor, Attorney, U.S. Department of Justice,

argued the cause for respondent. With him on the brief were

Robert G. Dreher, Acting Assistant Attorney General, U.S.

Department of Justice, and Michael Horowitz, Attorney, U.S.

Environmental Protection Agency.

William L. Wehrum Jr. argued the cause for intervenorsrespondent. With him on the brief were Lisa G. Dowden,

Melissa E. Birchard, Leslie Ritts, and David M. Friedland. 

Aaron M. Flynn entered an appearance.

Before: GARLAND, Chief Judge, WILLIAMS and RANDOLPH,

Senior Circuit Judges.

Opinion for the Court filed by Senior Circuit Judge

RANDOLPH.

RANDOLPH, Senior Circuit Judge: The State of Delaware,

industry and environmental organizations, and an industry

intervenor challenge a final rule of the Environmental Protection

Agency governing the use of certain kinds of power generators. 

See National Emission Standards for Hazardous Air Pollutants

for Reciprocating Internal Combustion Engines; New Source

Performance Standards for Stationary Internal Combustion

Engines, 78 Fed. Reg. 6,674 (Jan. 20, 2013). A group of trade

associations and corporations intervened in support of EPA. 

The generators are known as Reciprocating Internal Combustion

Engines. We refer to them here interchangeably as “backup
3

generators” or “emergency engines.” They typically run on

diesel fuel and expel numerous pollutants. See National

Emission Standards for Hazardous Air Pollutants for Stationary

Reciprocating Internal Combustion Engines, 69 Fed Reg.

33,474, 33,499 (June 15, 2004). 

Delaware raises three issues in its petition for judicial

review. First, it argues that EPA acted arbitrarily and

capriciouslywhen it modified the National Emissions Standards

for Hazardous Air Pollutants for the backup generators pursuant

to Section 112 of the Clean Air Act. 42 U.S.C. § 7412. Second,

it argues that, while modifying the National Emissions

Standards, EPA improperly revised the definition of the same

kind of generators in the New Source Performance Standards,

violating Section 111 of the Act. See 42 U.S.C. § 7411. And,

third, it argues that EPA unlawfully modified the National

Emissions Standards to exempt from emissions controls certain

non-emergency generators located in low-density areas.

All petitioners and the intervenor raise the first issue. 

Delaware alone raises the other two. Because we hold that

Delaware lacks standing to challenge the exemption from

emissions controls for backup generators in low-density areas,

we need not address the third issue. For the reasons that follow,

we hold that EPA acted arbitrarily and capriciously when it

modified the National Emissions Standards and the Performance

Standards to allow backup generators to operate without

emissions controls for up to 100 hours per year as part of an

emergency demand-response program.

I.

Congress enacted the Clean Air Act “to protect and enhance

the quality of the Nation’s air resources.” 42 U.S.C.

§ 7401(b)(1). The Act governs the emissions of hazardous air
4

pollutants that present “a threat of adverse human health effects

. . . or adverse environmental effects.” Id. § 7412(b)(2).

Section 112 requires EPA to promulgate national emissions

standards for both “major sources” and “area sources” of

hazardous air pollutants. See id. § 7412(d)(1). A “major

source” is “any stationary source” that emits “10 tons per year

or more of any hazardous air pollutant or 25 tons per year or

more of any combination of hazardous air pollutants.” Id.

§ 7412(a)(1). An “area source” is “any stationary source . . .

that is not a major source,” id. § 7412(a)(2), which is to say, any

stationary source that emits less than ten tons per year of any

hazardous air pollutant or less than twenty-five tons per year of

any combination of hazardous air pollutants. When

promulgating such standards, EPA must consider “the known or

anticipated adverse effects of such pollutants on public health

and the environment.” Id. § 7412(e)(2)(A).

Under Section 112, EPA “first sets emission floors for each

pollutant and source category and then determines whether

stricter standards, known as ‘beyond-the-floor’ limits, are

achievable in light of the factors listed in section 7412(d)(2).” 

Cement Kiln Recycling Coal. v. EPA, 255 F.3d 855, 858 (D.C.

Cir. 2001) (per curiam). Notably, these factors include the

“consideration [of] the cost of achieving such emission

reduction, and any non-air quality health and environmental

impacts and energy requirements.” 42 U.S.C. § 7412(d)(2).

Section 111 directs EPA to set emissions standards for new

and newly modified sources. Id. § 7411(d). A modified source

is one that has undergone “any physical change in, or change in

the method of operation[,] . . . which increases the amount of

any air pollutant emitted by such source or which results in the

emission of any air pollutant not previously emitted.” Id.

§ 7411(a)(4). Under Section 111, EPA must set standards for
5

emissions that “reflect[] the degree of emission limitation

achievable through the application of the best system of

emission reduction.” Id. § 7411(a)(1).

In rulemakings over the past decade, EPA has established

National Emissions Standards and Performance Standards for

pollutants emitted by backup generators. Such pollutants 1

include “[f]ormaldehyde, acrolein, methanol, and acetaldehyde.” 

69 Fed Reg. at 33,475. “[T]hese pollutants have been associated

with several health-related concerns, including cancer,

respiratory problems, and premature death.” Emission

Standards for Stationary Diesel Engines, 73 Fed. Reg. 4,136,

4,138 (Jan. 24, 2008).

Backup generators have traditionally been used in

emergency situations “to produce power for critical networks or

equipment . . . when electric power from the local utility is

interrupted.” 69 Fed. Reg. at 33,512. For years, they were not

subject to the same level of regulation as larger generators. See

id. at 33,477.

See generally National Emission Standards for Hazardous Air 1

Pollutants for Reciprocating Internal Combustion Engines, 75 Fed.

Reg. 51,570 (Aug. 20, 2010), National Emission Standards for

Hazardous Air Pollutants for Reciprocating Internal Combustion

Engines, 75 Fed. Reg. 9,648 (Mar. 3, 2010), Standards of Performance

for Stationary Spark Ignition Internal Combustion Engines and

National Emission Standards for Hazardous Air Pollutants for

Reciprocating Internal Combustion Engines, 73 Fed. Reg. 3,568 (Jan.

18, 2008), Standards of Performance for Stationary Compression

Ignition Internal Combustion Engines, 71 Fed. Reg. 39,154 (July 11,

2006), National Emission Standards for Hazardous Air Pollutants for

Stationary Reciprocating Internal Combustion Engines, 69 Fed. Reg.

33,474 (June 15, 2004).
6

That began to change in 2004, when EPA promulgated a

rule allowing backup generators to operate without emissions

controls for unlimited periods “in emergency situations and for

routine testing and maintenance.” Id. at 33,512. It also allowed

them to operate without emissions controls for “an additional 50

hours per year in non-emergency situations.” Id. Four years

later, EPA became “concerned that if stationary emergency

engines are allowed to operate in non-emergency situations[,]

they may be inappropriately used for peaking power”—that is,

to supply power to an energy grid during periods of high

demand—and, accordingly, EPA specified “that the 50 hours

allowed for non-emergencysituations cannot be used to generate

income for a facility to supply power to an electric grid or

otherwise supply power as part of a financial arrangement with

another entity.” 73 Fed. Reg. at 3,583.

In two separate rules in 2010, EPA promulgated standards

for hazardous air pollutant emissions from backup generators. 

The regulations allowed backup generators to operate without

emissions controls for fifteen hours each year as part of

“demand response programs” during “emergencyconditionsthat

could lead to a potential electrical blackout.” 75 Fed. Reg.

9,648, 9,667, 9,677 (Mar. 3, 2010) (rule for compression

ignition engines); see also 75 Fed. Reg. 51,570, 51,591 (Aug.

20, 2010) (rule for spark ignition engines) (collectively, the

“2010 Rule”). Demand response programs, which we discuss

more below, are programs through which customers reduce their

consumption of electric energy from the grid in response to high

prices or other incentives. See 18 C.F.R. § 35.28(b)(4). 

“Soon after the 2010 rule was final, the EPA received

petitions for reconsideration of the 15-hour limitation for

emergency demand response . . ..” 78 Fed. Reg. at 6,679. On

June 7, 2012, as a result of these petitions, EPA proposed

amendments for National Emissions Standards for stationary
7

backup generators and amendments to the Performance

Standards for stationary internal combustion engines. See 40

C.F.R. Ch. I, Subch. C., Pt. 63, Subpt. ZZZZ (National Emission

Standards); 40 C.F.R. Ch. I, Subch. C., Pt. 60, Subpt. IIII & JJJJ

(Performance Standards).

EPA’s final rule, issued on January 30, 2013, radically

revised the fifteen-hour limit. The rule’s preamble described its

purpose as addressing the “use of existing engines for

emergency demand response and system reliability” and noted

that using such generators “as part of emergency demand

response programs can help prevent grid failure or blackouts.” 

78 Fed. Reg. at 6,679. Under the new rule, backup generators

are permitted to operate exempt from emissions controls for

“emergency demand response” for up to 100 hours each year, in

addition to actual emergency situations and maintenance. Id. at

6,679-80, 6,704-05; see also id. at 6,681, 6,695-97 (modifying

Performance Standards for consistency). The rule limits

emergency demand response operation to two circumstances:

first, when a “Reliability Coordinator” (such as an independent

electric grid operator) “has declared an EnergyEmergencyAlert

Level 2,” or, second, when “there is a deviation of voltage or

frequency of [five] percent or greater below standard voltage or

frequency.” Id. at 6,705.2

Petitioners filed a timely petition for review on April 1,

2013. See 42 U.S.C. § 7607(b)(1); FED. R. APP. P. 15.

The 2013 Rule explains that, during a Level 2 alert, “there is 2

insufficient energy supply and a true potential for electrical

blackouts.” 78 Fed. Reg. at 6,679. There is disagreement in the

record whether the term“emergency demand response” is a misnomer. 

We do not resolve that issue here and understand “emergency” in this

context to mean the circumstances during which the 2013 Rule allows

backup generators to operate for up to 100 hours.
8

II.

Before turning to the merits of the case, we address the

threshold issue of standing. See Steel Co. v. Citizens for a Better

Env’t, 523 U.S. 83, 101 (1998).

To establish standing under Article III of the Constitution,

a petitioner “bears the burden of averring facts in its opening

brief” that “demonstrate it has suffered a concrete and

particularized injury that is imminent and not conjectural, that

was caused by the challenged action, and that is likely to be

redressed by a favorable judicial decision.” Texas v. EPA, 726

F.3d 180, 198 (D.C. Cir. 2013) (citing Sierra Club v. EPA, 292

F.3d 895, 899-901 (D.C. Cir. 2002) and Lujan v. Defenders of

Wildlife, 504 U.S. 555, 560-61 (1992)). When considering

standing, we assume the validity of the petitioner’s merits

argument. See Del. Dep’t of Natural Res. & Envtl. Control v.

FERC, 558 F.3d 575, 578 (D.C. Cir. 2009).

Petitioner Conservation Law Foundation, “a private,

nonprofit membership organization dedicated to the protection

of public health and New England’s environment,” asserts that

its “members live, work, and recreate in areas affected by

emissions from diesel generators, particularlydensely populated

urban areas.” Pet’r FirstEnergy, et al. Br. at 16. For an

association to have standing, “it must demonstrate that at least

one member would have standing under Article III to sue in his

or her own right, that the interests it seeks to protect are germane

to its purposes, and that neither the claim asserted nor the relief

requested requires that an individual member participate in the

lawsuit.” NRDC v. EPA, 489 F.3d 1364 (D.C. Cir. 2007) (citing

Hunt v. Wash. State Apple Adver. Comm’n, 432 U.S. 333, 342-

43 (1977)). Here, the Foundation claims that “the challenged

rule will increase emissions of harmful air pollutants from

[backup generators], threatening the health and welfare of CLF’s
9

members.” Pet’r FirstEnergy, et al. Br. at 16 (citing Exs. A-C). 

The Foundation provided declarations from two of its members

to that specific effect. Since these members assert harm

traceable to the rise in backup generator emissions that would be

redressable by government action, their interests in health are

germane to the Foundation’s purposes, and individual

participation in the lawsuit is not required, the Foundation has

standing. See Sierra Club v. EPA, 699 F.3d 530, 533 (D.C. Cir.

2012).

Petitioners FirstEnergySolutions Corp., Calpine Corp., and

PSEG Power LLC (collectively, the “Generator Petitioners”)

claim to have standing based on the alleged distorting impact the

2013 Rule has on organized capacity markets in which the

Generator Petitioners compete. Intervenor Electric Power

Supply Association asserts standing for the same reason. We

need not address this argument, since the Generator Petitioners

have submitted a joint brief with the Foundation, and the

Association raises the same claims as raised in the joint brief. 

Because “constitutional and prudential standing can be shown

for at least one plaintiff, we need not consider the standing of

the other plaintiffs to raise that claim.” Mountain States Legal

Found. v. Glickman, 92 F.3d 1228, 1232 (D.C. Cir. 1996).3

Delaware asks us to vacate three portions of the 2013 Rule:

the modified National Emissions Standards that allow for 100

hours of demand response, the similarly revised Performance

Standards, and the exemption from emissions controls of certain

non-emergency generators located in remote areas.

EPA concedes that the Foundation “does appear to have

3

standing” and that the Electric Power Supply Association asserts the

same issue raised in the Foundation’s joint brief. Resp’t Br. at 1 n.1.
10

EPA challenges Delaware’s standing to bring any of these

claims. It argues Delaware did not satisfy its burden of

identifying “actual or imminent and concrete and particularized

injury stemming from” EPA actions. Resp’t Br. at 2-3 (internal

quotation marks omitted). Indeed, Delaware’s argument in

favor of standing in its opening brief is thin. In a single

paragraph, Delaware asserts that its standing is “self evident,”

Pet’r Del. Br. at 11 (citing Sierra Club, 292 F.3d at 900),

arguing its “air quality is impacted by emissions from the

engines covered by the [Performance Standards] and [National

Emissions Standards] that originate upwind.” Id. The added

pollution will, so Delaware argues, negatively impact

Delaware’s ability to attain the National Ambient Air Quality

Standards (“NAAQS”) that Delaware has to maintain pursuant

to the Clean Air Act. Id. In its opening brief, Delaware offers

no specific evidence that the winds carry pollutants from backup

generators into the state, or in what quantity, or with what

frequency, or that backup generators in the remote-area

subcategory are located near enough to Delaware to pose a

threat to the state’s air quality. Its brief also points to no

specific place in the record, which extends for thousands of

pages, where that information could be found. Its only

additional authority is Massachusetts v. EPA, 549 U.S. 497,

516-25 (2007) (holding state petitioners had standing to

challenge EPA order denying a petition for rulemaking to

regulate greenhouse gas emissions from motor vehicles).

Typically the petitioner “bears the burden of averring facts

in its opening brief” that establish standing. Texas v. EPA, 726

F.3d at 198; see also D.C. CIR. R. 28(a)(7) (“When the . . .

petitioner’s standing is not apparent from the administrative

record, the brief must include arguments and evidence

establishing the claim of standing.”). Taken by themselves, the

bare assertions in the opening brief may be insufficient to

establish standing.
11

But our case law allows us the discretion to look beyond the

opening brief and consider material submitted later if the

petitioner “reasonably believed [its] standing [wa]s

self-evident.” Am. Library Ass’n v. FCC, 401 F.3d 489, 492

(D.C. Cir. 2005); see also Ctr. for Sustainable Econ. v. Jewell,

779 F.3d 588, 598-99 (D.C. Cir. 2015); Ams. for Safe Access v.

Drug Enforcement Admin., 706 F.3d 438, 444 (D.C. Cir. 2013).

We choose to exercise that discretion here for three reasons. 

First, Delaware is part of PJM Interconnection, LLC—the

regional transmission organization that operates the power grid

for over 60 million customers in the mid-Atlantic region and the

Midwest. See J.A. 1,790. As we will discuss below, part of

EPA’s motivation for this rule was to allow the use of

emergency engines for demand response in the PJM region, and

EPA explicitly sought to accommodate what it believed to be a

PJM-specific sixty-hour availability requirement for emergency

engines. See 78 Fed. Reg. at 6,679; National Emission

Standards for Hazardous Air Pollutants for Reciprocating

Internal Combustion Engines; New Source Performance

Standards for Stationary Internal Combustion Engines, 77 Fed.

Reg. 33,812, 33,817 (proposed June 7, 2012). There is evidence

in the administrative record that backup generators represent

nearly fifteen percent of demand response in the PJM region and

that demand response use is growing therein. See J.A. 2,114. 

Second, the congressionally created Northeast Ozone Transport

Region includes Delaware and other states in the mid-Atlantic

and northeast regions, see 42 U.S.C. § 7511c, and we have

previously noted that ozone pollution from these states

contributes to pollution in each other. See Virginia v. EPA, 108

F.3d 1397, 1401 (D.C. Cir. 1997); see also Appalachian Power

Co. v. EPA, 249 F.3d 1032, 1036-37 (D.C. Cir. 2001) (per

curiam) (describing EPA finding that stationary source

emissions in upwind states contributed to ozone nonattainment

in other states and “trigger[ed] direct federal regulation of
12

stationary sources”). Third, parts of Delaware are in

nonattainment, and its experts aver that most of the emissions

that negatively impact its ability to attain the NAAQS come

from out of state. See Addendum to Pet’r Del. Reply Br. at 4;

see also EPA, Current Nonattainment Counties for All Criteria

Pollutants, http://www.epa.gov/airquality/greenbook/ancl.html

(last visited Apr. 22, 2015) (listing counties in nonattainment).

In light of these factors, it was reasonable for Delaware to

believe that its standing was self-evident. Accordingly, we look

beyond the opening brief to the reply brief to establish standing. 

See Ams. for Safe Access, 706 F.3d at 444; Am. Library Ass’n,

401 F.3d at 495-96; see also Communities Against Runway

Expansion, Inc. v. FAA, 355 F.3d 678, 685 (D.C. Cir. 2004)

(looking to supplemental declarations submitted with reply brief

to establish injury and, thus, standing).

Delaware’s reply brief and its accompanying addendum

provide an explanation of the injuries that gave rise to

Delaware’s reasonable belief that its standing was self-evident. 

It cites a letter in the record sent by Ali Mirzakhalili, Director of

Delaware’s Department of Natural Resources and

Environmental Control’s Division of Air Quality, to EPA in

August 2012, see J.A. 2,107-08, and provides in an addendum

two affidavits, one from Mirzakhalili and another from Marty

Prettyman, a Delaware environmental scientist, see Addendum

to Pet’r Del. Reply Br. at 1-17, 20-29. 

In his letter, Mirzakhalili argues that the EPA rule would

have an “adverse” impact on air quality and that “[i]t is of vital

importance not to increase emissions of oxides of nitrogen

x

(NO ), especially on high electricity demand days.” J.A. 2,107. 

He also argues a lower ambient air quality standard is “looming”

x

that “will require additional NO emission reductions,” and

EPA’s proposed xrule “increases rather than decreases NO
13

emissions that contribute to the formation of ozone.” J.A.

2,107-08. In his affidavit, Mirzakhalili states that emissions

from emergencydemand response programssignificantlyimpact

ozone pollution in Delaware, Addendum to Pet’r Del. ReplyBr.

at 10, that at least 90 percent of the pollutants contributing to

Delaware’s failure to attain the NAAQS “come from pollutants

transported from other states,” id. at 3, that such pollution incurs

medical costs that are borne by the state, id. at 4-5, and that

stronger emissions controls on backup generators in other states

would benefit Delaware, id. at 11-12. Prettyman charts the

rising number of demand response incidents in the PJM regional

power grid, id. at 23, and states that the remote area exemption

for certain engines poses an environmental hazard, id. at 24-25,

though it is unclear if such engines are within or proximate to

Delaware.

This evidence suffices to establish that Delaware has

suffered a concrete and imminent injury stemming from the

portions of the 2013 Rule allowing backup generators to operate

without emissions controls for up to 100 hours per year as part

of an emergency demand-response program. See Appalachian

Power, 249 F.3d at 1066-67; see also Massachusetts v. EPA,

549 U.S. at 521. Thus, Delaware’s challenges to the modified

National Emissions Standards and the related Performance

Standards are properly before us.

But a petitioner “must demonstrate standing for each claim

he seeks to press,” DaimlerChrysler Corp. v. Cuno, 547 U.S.

332, 352 (2006), and Delaware’s challenge to the exemption

from emissions controls of certain non-emergency generators

located in remote areas is another matter.

In both its opening brief and its reply brief, Delaware offers

no evidence that backup generators in the remote-area

subcategory are located near enough to Delaware to pose a
14

threat to the state’s air quality. To the contrary, the Mirzakhalili

letter cited in Delaware’s reply brief states that “[m]ost of these

installations are in remote, unpopulated areas.” J.A. 2,122. The

only examples the letter offers of these remote locations are

references to the Powder River Basin of Wyoming and “fields”

of generators “visibly evident across Wyoming and Colorado,

and . . . throughout Nebraska and California.” J.A. 2,122-23. 

Nothing in Delaware’s briefs or supplemental affidavits

mentions a location in or near Delaware or even upwind of the

state. Considered alongside Delaware’s credible claims of

injury from backup generators in upwind and contiguous states,

its assertions regarding remote-area engines are strikingly weak. 

Accordingly, Delaware has failed to meet its burden of showing

that it has standing to challenge the 2013 Rule’s

subcategorization of existing stationary spark ignition engines

located at area sources in sparsely populated areas. See Ass’n of

Flight Attendants-CWA, AFL-CIO v. U.S. Dep’t of Transp., 564

F.3d 462, 467 (D.C. Cir. 2009) (considering but rejecting

standing arguments made in reply brief and accompanying

submissions).

Accordingly, we address only EPA’s modification of the

National Emissions Standards and the Performance Standards to

allow backup generators to operate without emissions controls

for up to 100 hours per year as part of an emergency

demand-response program, see 40 C.F.R. §§ 60.4211(f)(2),

60.4243(d)(2), 63.6640(f)(2), and we do not address the remotearea exemption, see 40 C.F.R. § 63.6675.

III.

We “may reverse” a final EPA rule if we find the agency’s

action “arbitrary, capricious, an abuse of discretion, or otherwise

not in accordance with law.” 42 U.S.C. § 7607(d)(9)(A). This

language from the Clean Air Act differs from that of the
15

Administrative Procedure Act. Section 706 of the APA states

that the “reviewing court shall” “hold unlawful and set aside

agency action” the court finds to be “arbitrary, capricious, an

abuse of discretion, or otherwise not in accordance with law,” 5

U.S.C. § 706(2)(A). But “the standard we apply is essentially

the same under either Act,” the CAA or the APA. Ethyl Corp.

v. EPA, 51 F.3d 1053, 1064 (D.C. Cir. 1995); see also West

Virginia v. EPA, 362 F.3d 861, 867-68 (D.C. Cir. 2004).

To prevail, an “agency must ‘examine the relevant data and

articulate a satisfactory explanation for its action including a

rational connection between the facts found and the choice

made.’” Nat’l Shooting Sports Found., Inc. v. Jones, 716 F.3d

200, 214 (D.C. Cir. 2013) (quoting Motor Vehicle Mfrs. Ass’n

v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 43 (1983)

(quotation marks omitted)). “To be regarded as rational, an

agency must also consider significant alternatives to the course

it ultimately chooses.” Allied Local & Reg’l Mfrs. Caucus v.

EPA, 215 F.3d 61, 80 (D.C. Cir. 2000). We will reverse when

agency action is “based on speculation,” Jones, 716 F.3d at 214,

or when the agency did not “engage the arguments raised before

it,” NorAm Gas Transmission Co. v. FERC, 148 F.3d 1158, 1165

(D.C. Cir. 1998) (quoting K N Energy, Inc. v. FERC, 968 F.2d

1295, 1303 (D.C. Cir. 1992)).

IV.

To understand this case and petitioners’ claims, we must

discuss energy markets and capacity markets and their

relationship to demand response. 

Under the Federal Power Act, the Federal Energy

Regulatory Commission (“FERC”) has jurisdiction over the

“transmission of electric energy in interstate commerce,” 16

U.S.C. § 824(b)(1), and is responsible for maintaining the
16

reliability of the electric grid, see id. § 824o(b)(1). FERC has

certified the North American Electric Reliability Corporation

(“NERC”) as the nation’s “electric reliability organization,” and

NERC has developed enforceable standards to ensure electric

grid reliability. See Alcoa, Inc. v. FERC, 564 F.3d 1342, 1344-

45 (D.C. Cir. 2009). FERC regulates electricity grid managers

known as Independent System Operators (“ISOs”) or Regional

Transmission Organizations (“RTOs”) (collectively, “System

Operators”), who are responsible for ensuring electric reliability

within their regions of responsibility. See Braintree Elec. Light

Dep’t v. FERC, 550 F.3d 6, 8-9 (D.C. Cir. 2008) (describing

history of RTOs).4

These System Operators are usually involved in both the

energy and capacity markets. Energy “is the amount of

electricity generators actually provide to the grid and is available

to be used at any moment. Organized wholesale electricity

markets buy and supply electricity instantaneously.” Kennedy

Maize, Texas and the Capacity Market Debate, Power Mag.,

Feb. 1, 2014.5

Capacity is different. “‘Capacity’ is not electricity itself but

the ability to produce it when necessary. It amounts to a kind of

call option that electricity transmitters purchase from

See also Michael H. Brown & Richard P. Sedano, Electricity 4

Transmission: A Primer 53 (2004) (describing responsibilities of grid

operators).

See also Brown & Sedano, Electricity Transmission at 67 5

(defining the “wholesale power market” as “[t]he purchase and sale of

electricity from generators to resellers . . . along with the ancillary

services needed to maintain reliability and power quality at the

transmission level”); J.A. 2,399 (“[A]ctual system load (real-time

customer demand) is met via the energy and other daily markets.”)

(Analysis Group Report).
17

parties—generally, generators—who can either producemore or

consume less when required.” Conn. Dep’t of Pub. Util. Control

v. FERC, 569 F.3d 477, 479 (D.C. Cir. 2009); see also Me. Pub.

Util. Comm’n v. FERC, 520 F.3d 464, 467 (D.C. Cir. 2008) (per

curiam), rev’d in part sub nom. NRG Power Mktg., LLC v. Me.

Pub. Util. Comm’n, 558 U.S. 165 (2010). These sales may

occur years in advance of when the capacity is actually needed;

power generators are thus able to plan and build facilities to

meet future demand. See Md. Pub. Serv. Comm’n v. FERC, 632

F.3d 1283, 1284-85 (D.C. Cir. 2011) (per curiam). 

ISOs and RTOs typically require local utilities delivering

electricity to users (known as “load-serving entities,” or LSEs)

to purchase a certain amount of capacity to ensure reliability

during periods of high demand. See, e.g., Elec. Consumers Res.

Council v. FERC, 407 F.3d 1232, 1234 (D.C. Cir. 2005). “The

goal is for [utilities] to purchase sufficient capacity to easily

meet expected peaks in electricity demand on their transmission

systems.” Conn. Dep’t of Pub. Util. Control, 569 F.3d at 479.

“Payments for capacity provide a revenue stream to

maintain and keep current resources operating and to develop

new resources. Investors need sufficient long-term price signals

to encourage the maintenance and development of generation,

transmission and demand-side resources.” PJM, Reliability

Pricing Model, Demand Response and Energy Efficiency 1

(2009); see also PJM Interconnection, LLC, 128 FERC ¶ 61157

P 24 (Aug. 14, 2009) (“Since energy and ancillary services

revenues in an export area are not sufficient by themselves to

support new entry, capacity payments are needed to provide the

proper incentives for new efficient entry in that area and to

retain existing efficient generators over the long term.”).

Capacity markets vary across the country, but “the primary

goal of each of these markets is the same: ensure resource
18

adequacy at just and reasonable rates through a market-based

mechanism that is not unduly discriminatory or preferential as

to the procurement of resources.” FERC Staff, AD13-7-000,

Centralized CapacityMarket Design Elements 2 (2013); see also

N.E. Power Generators Ass’n v. FERC, 707 F.3d 364, 367 (D.C.

Cir. 2013). In some markets, System Operators administer

auctions whereby LSEs procure capacity. See Centralized

Capacity Market Design at 1-2.

We recently explained how the process works in New York. 

There, “[c]apacity suppliers bid a quantity of capacity into the

auction, and the total amount of capacity bid creates a supply

curve, which intersects with a predetermined demand curve.” 

TC Ravenswood, LLC v. FERC, 741 F.3d 112, 114 (D.C. Cir.

2013). Supply and demand meet to set a price, which LSEs pay

to purchase capacity. Id. “In theory, this market design

encourages desirable investment by signaling the need for more

generation and by enabling power generators to recoup their

costs in the capacity market.” Id. 

Capacity auctions do “not differentiate among capacity

resources based on any type of resource specific reliability

criteria.” J.A. 2,397 (Analysis Group Report). The capacity

markets select resources almost exclusively on the basis of

price—they do not place a value on “fuel type, technology type,

or resource flexibility.” Id.; see also TC Ravenswood, 741 F.3d

at 114; Conn. Dep’t of Pub. Util. Control, 569 F.3d at 479-80.

Capacity can be supplied by power plants, but it can also be

supplied bydemand-response resources. Traditionally, “demand

response” simply referred to “a reduction in the consumption of

electric energy by customers.” See 18 C.F.R. § 35.28(b)(4).6

See also FERC Staff, National Action Plan on Demand 6

Response, Docket No. AD09-10, at 3 (2010), available at
19

For example, a consumer may temporarily shut off air

conditioning on a hot day.

Industry and environmental petitioners are concerned with

what they consider a new phenomenon in demand response,

whereby some consumers substitute the supply of capacity from

traditional sources with backup generators. Consumers draw

energy from the generators and not from the grid, “which

reduces electricity consumption from the grid as measured at the

customer’s meter,” according to a report in the administrative

record. J.A. 2,142. By doing so, they “displace[] electricity that

otherwise would be provided by the grid.” J.A. 2,391 (Analysis

Group Report). So-called “demand response ‘aggregators’ have

adopted the practice of grouping backup generators together to

form ‘virtual power plants’ of considerable size,” according to

comments presented to EPA by intervenor Electric Power

Supply Association. J.A. 2,223-24.7

The performance obligations for these demand response

providers and traditional generators differ; traditional generators

have a “must-offer requirement” in accordance with which they

http://www.ferc.gov/legal/staff-reports/06-17-10-demand-response.pdf

(FERC uses “‘demand response’ to refer to the ability of customers to

respond to either a reliability trigger or a price trigger from their utility

system operator, load-serving entity, regional transmission

organization/independent system operator (RTO/ISO), or other

demand response provider by lowering their power consumption.”).

Respondent-Intervenor EnerNOC, Inc.—a corporation that 7

specializes in demand response and partly relies on the use of backup

generators subject to the 2013 Rule—claims on its website that it is

“rapidly building the world’s largest virtual power plant.” EnerNOC,

Our Impact, http://www.enernoc.com/about/our-impact (last visited

Apr. 22, 2015).
20

provide energy into the grid whenever “called upon,” but

“demand response capacity resources,” like backup generators,

“are not subject to the must-offer requirements,” absent system

emergencies. Centralized Capacity Market Design at 19. 

Petitioners and the supporting intervenor argue that demand

response in capacity markets based on backup generators is

growing with negative effects on reliability and the

environment. They argue there are four reasons why. First,

because backup generators do not have to conform to emissions

controls like regular power plants, their electricity costs less to

produce and they can charge less and underbid conventional

power suppliers in capacity markets. Second, as backup

generators displace traditional power plants in capacitymarkets,

demand for traditional power generation drops, and—because

traditional power generators rely on capacitymarkets to “recoup

their costs,” TC Ravenswood, 741 F.3d at 114—they underinvest in power plants that produce electricity for the energy

markets. This reduction in supply undermines the reliability of

the power grid. Third, as the power supply decreases and the

grid becomes less stable, the number of power emergencies

increases. And, fourth, as emergencies increase, the actual use

of “dirty” backup generators correspondinglyincreases, causing

greater pollution. In short, petitioners and the intervenor argue

that instead of protecting the nation’s air resources and

improving grid reliability as EPA claims, the 2013 Rule has the

opposite effect.

V.

During the notice and comment period, petitioners

presented their concerns about the 2013 Rule’s impact on the

efficiency and reliability of the energy grid. They contend that

EPA should have, but did not, respond properly to their well-
21

founded concerns. See Allied Local & Reg’l Mfrs. Caucus, 215

F.3d at 80.

Petitioners are correct. EPA’s action was arbitrary and

capricious on that ground alone. In addition, EPA appears to

have relied on faulty evidence when justifying the exemption

increase from fifteen hours to 100 hours. EPA also did not

consider the alternative of limiting the exception to parts of the

country not served by organized capacity markets. We should

further note that EPA did not obtain the views of FERC or

NERC on the reliability considerations upon which EPA based

the exemption.

1. Efficiency and Reliability

Several commenters explained how EPA’s final rule

threatens the efficiency and reliability of the energy markets by

creating incentives for backup generators to enter the capacity

markets and force out more efficient, traditional power

generators.

For instance, at a hearing for public comments on the

proposed rule in July 2012, Christina E. Simeone of the nonprofit PennFuture Energy Center testified that the 2013 Rule

would “create distortions in energy markets by making demand

response from uncontrolled [backup] units artificially cheap.” 

J.A. 1,697. She pointed to evidence showing that demand

response programs were growing in the region overseen by PJM

Interconnection. By making backup generators “artificially

cheap, EPA is creating a rush to these resources,” and, thus,

harming reliability by diverting investment from power

generation resources “needed to secure the grid.” J.A. 1,699. 

At the same hearing, Shannon Maher Banaga of Petitioner

PSEG Power, LLC testified that demand response resources
22

were not needed to ensure reliability. J.A. 1,703. Backup

generators are “economic resource[s]” that “comp[]ete[] directly

with other forms of capacity, most particularly generation,” she

said. J.A. 1,705. As backup generators play a larger role in

capacity markets, “the number of so-called ‘emergencies’ is

going to go up.” J.A. 1,706.

In August 2012, Monitoring Analytics, LLC, acting in its

capacity as the Independent Market Monitor (“IMM”) for PJM,

submitted comments to EPA objecting strongly to the reliability

rationale of the proposed rule. “Some have asserted that an

exemption for [backup] generators participating in demand side

response [ ] programs provides benefits to the organized

wholesale electricity markets,” it wrote. J.A. 2,338. “Those

arguments have no merit. On the contrary, providing the

exemption will have negative consequences for efficiency and

reliability.” Id. It argued the 100-hour exemption “conflicts

with and would undermine the development of the demand side

of these markets” and is totally unnecessary to support

reliability. Id. According to IMM, given the interplay between

the capacity and energy markets, the exemption would distort

both. See J.A. 2,340-41.

Petitioner Calpine Corporation submitted a letter to EPA in

August 2012 echoing these concerns. The proposed rule “would

incentivize the procurement of diesel-fired [behind-the-meter]

generators masquerading as ‘demand response’ in electricity

capacity markets and thereby displace clean generating

resources . . ..” J.A. 2,355. Backup generators are not necessary

for reliability in organized competitive markets, since “the

market will simply procure other resources instead of [a behindthe-meter generator] that has not had to internalize the costs of

emissions controls.” Id. Indeed, the increased reliance on

demand-response resources available in capacity markets “may

actually impair system reliability” since the traditional power
23

generators they displace “operate more reliably” than the

demand-response resources. J.A. 2,356. “Simply put, the

Proposed Rule’s exemption is nothing less than a subsidy for

dirty generating sources.” Id.

Nor were these concerns merely hypothetical. An August

2012 report submitted to EPA by Northeast States for

Coordinated Air Use Management, a non-profit association of

air quality agencies in the northeast, explained that “demand

response programs appear to be shifting a portion of overall

electricity demand from traditional generating resources that

supply the grid to more dispersed, unregulated diesel

generators.” J.A. 2,142; cf. J.A. 1,711, 1,757 (comments

showing an increase in demand-response resources offered into

auction from 2009 to 2010). 

EPA offered wan responses to these comments. EPA

construed the concerns as arguments that the 2013 Rule “will

encourage the use of backup generators in lieu of cleaner

alternatives of energy” but “there is no guarantee that this would

be the case.” J.A. 2,579. EPA seems to have missed the forest

for the trees: the overriding concern of these comments was the

perverse effect the 100-hour exemption would have on the

reliability and efficiency of the capacity and energy markets, not

the specific clean energy alternatives that could supply the grid

instead of backup generators. EPA essentially said that it was

not its job to worry about those concerns: “The issues related

[to] management of energy markets and competition between

various forms of electric generation are far afield from EPA’s

responsibilities for setting standards under the CAA.” J.A.

2,582; see also J.A. 2,592 (“Decisions about what units to allow

to be bid into the capacity market and relied on for reliability are

not under the EPA’s purview and should be left to the entities
24

that are responsible for maintaining the reliability of the electric

grid.”).8

But EPA cannot get away so easily from its obligations

under the APA to respond to “relevant and significant”

comments. Cement Kiln Recycling Coal. v. EPA, 493 F.3d 207,

225 (D.C. Cir. 2007) (quoting Grand Canyon Air Tour Coal. v.

FAA, 154 F.3d 455, 468 (D.C. Cir. 1998)). Naturally, an agency

need not “discuss every item of fact or opinion included in the

submissions made to it.” Pub. Citizen, Inc. v. FAA, 988 F.2d

186, 197 (D.C. Cir. 1993) (quoting Auto. Parts & Accessories

Ass’n v. Boyd, 407 F.2d 330, 338 (D.C. Cir. 1968)). But an

agency must respond sufficiently to “enable us to see what

major issues of policy were ventilated . . . and why the agency

reacted to them as it did.” Id. (quoting Auto. Parts, 407 F.2d at

335) (ellipsis in original). 

EPA did not even do that much. It refused to engage with

the commenters’ dynamic markets argument. At points, its later

statements contradicted earlier responses; while the final rule

placed reliability at the center of its reasoning, see 78 Fed. Reg.

at 6,679, EPA’s response to comments insisted it was not

“justifying its regulation primarily on the reliability needs of the

bulk powersystem.” J.A. 2,592; cf. Farmers Union Cent. Exch.,

Inc. v. FERC, 734 F.2d 1486, 1520 (D.C. Cir. 1984) (“Such

self-contradictory, wandering logic does not constitute an

adequate explanation” of agency action). EPA seeks to excuse

its inadequate responses by passing the entire issue off onto a

different agency. Administrative law does not permit such a

EPA also responded to these comments by noting that areas of 8

the country not served by organized capacity markets do rely on

backup generators to protect the reliability of the grid. See, e.g., J.A.

2,580. We find this response equally inadequate for the reasons

explained in Part V.3.
25

dodge. See Gen. Chem. Corp. v. United States, 817 F.2d 844,

846 (D.C. Cir. 1987) (per curiam) (finding agency action

arbitrary and capricious where agency analysis was

“inadequately explained”).

During oral argument, EPA’s attorney told the court that

EPA “heard” the commenters’ concerns about the 2013 Rule. 

But merely hearing is not good enough—EPA must respond to

serious objections. See Allied Local & Reg’l Mfrs. Caucus, 215

F.3d at 80. By failing to do so here, its rulemaking was arbitrary

and capricious. See State Farm, 463 U.S. at 43-44.

2. Backup Generator Aggregation

EPA’s 100-hour exemption in the 2013 Rule was arbitrary

and capricious for still another reason: EPA failed to respond to

comments suggesting that the 100-hour limit was based on

faulty evidence.

In support of its claim that the fifteen-hour cap was

inadequate, EPA specifically relied on comments from a prior

rulemaking, see J.A. 1,548 (PJM Comment from Feb. 14, 2011),

indicating that resources were required to be available for a

minimum of sixty hours per year to participate in PJM’s

“Emergency Load Response Program.” See 78 Fed. Reg. at

6,679.

But, as PJM explained to EPA in comments written in

August 2012 in response to this rule, the sixty-hour minimum

does not apply to individual engines. J.A. 1791. Rather, these

engines may be aggregated together to meet the sixty-hour

availability requirement. Id. PJM explained that in 2012 “the

environmental limitations on individual [backup] units . . . are

not necessarily dispositive of the ability of demand response

resources to participate in PJM’s markets or to maintain bulk
26

power system reliability.” Id.; see also J.A. 2346-47 (IMM

Comments); J.A. 2,104-05 (CLF Comments). 

EPA seems to have either intentionally discounted PJM’s

later explanation of its requirement or simply confused the later

comment for the earlier one. Another commenter brought the

possible confusion to EPA’s attention, but EPA did not

specifically respond, saying it considered demand-resource

needs “in all areas of the country, not just PJM.” J.A. 2,596. 

And yet, EPA significantly grounded the 2013 Rule in a PJM

requirement that does not exist for individual engines. 

In light of PJM’s 2012 comments, EPA failed to give an

adequate reason for relying on the PJM availability requirement. 

See 78 Fed. Reg. at 6,679. EPA’s action was thus arbitrary and

capricious on this ground, as well. See State Farm, 463 U.S. at

43; see also Nat’l Gypsum Co. v. EPA, 968 F.2d 40, 41 (D.C.

Cir. 1992) (vacating and remanding where EPA offered

inadequate scientific evidence and failed to offer substantial

evidence for decision). 

3. Alternative Option

Petitioners argue that backup generator-based demand

response resources “simply provide a reliability service that

could and would be equally met by alternative

resources”—traditional energy generators that comply with

emissions controls—especially in organized capacity markets. 

Pet’r FirstEnergy, et al. Br. at 22 (citing Analysis Group

Report).

EPA counters that petitioners “ignore[] that resources other

than emergency engines are typically unavailable for emergency

demand response purposes in those areas of the nation not

served by organized capacity markets.” Resp’t Br. at 39-40. 
27

EPA argues that by setting a nationwide annual limit of 100

hours, it “took into account the fact that emergency engines help

to ensure reliable electric service not just in areas with organized

capacity markets, but also in many rural communities and small

municipal systems.” Id. at 45.

This statement does not explain whyEPA failed to limit the

100-hour exemption to areas of the country not served by

organized markets. At least one commenter, the Electric Power

Generation Association, proposed such an alternative. See J.A.

1,780-83. Tens of millions of Americans live in states served by

organized markets. Yes, EPA received comments that 9

exempting backup generatorsfrom emissions controls would aid

reliability “for small, rural municipalities,” J.A. 2,556; see also

J.A. 1,931-32, J.A. 1,944, but it did not adequately explain why

it adopted a nationwide rule when such an allegedly overbroad

action has the potential to distort organized markets. EPA

asserts that it “was perfectly reasonable” for it “to promulgate a

rule of nationwide applicability, rather than establish different

limits on emergency demand response operation based on the

specific (and not necessarily permanent) market conditions in a

particular location.” Resp’t Br. at 48. 

For support, EPA cites National Telephone Co-Op

Association v. FCC, 563 F.3d 536 (D.C. Cir. 2009), in which we

held that the Federal Communications Commission’s

explanation of its rejection of an alternative policy option “was

reasonable and reasonably explained.” Id. at 542; see also

Resp’t Br. at 48. But that case is instructive for exactly what is

lacking in EPA’s actions in the instant case. There, petitioner

argued that the FCC could have created a “partial or blanket

exemption” from an order requiring the portability of telephone

See FERC, Docket No. MO4-2-000, State of the Markets

9

Report 5-6 (2004).
28

numbers for “small wireline carriers.” Id. The FCC rejected the

proposal after carefully articulating its reasons, noting the

proposal “would harm consumers in small and rural areas across

the country by preventing them from being able to port [or

transfer their numbers] on a permanent basis” and discourage

further competition that could help customers. See id.; In re

Telephone Number Requirements for IP-Enabled Services

Providers, 22 F.C.C.R. 19531, 19611 ¶16 2007 WL 3306343

(2007). In short, the FCC identified a specific harm of the

alternative proposal. 

Here, the only rationale provided for a national rule was a

vague desire for uniformity. While EPA emphasized in the 10

administrative proceeding the benefits to rural areas of the rule,

see, e.g., J.A. 2,596, it did not address why a more limited rule

would not achieve the same outcome without posing risks to

organized energy markets. 

We do not “broadly require an agency to consider all policy

alternatives in reaching [a] decision.” State Farm, 463 U.S. at

51. But “[a]t the very least this alternative way of achieving”

EPA’s objective, namely by limiting the 100-hour exemption to

address the reliability needs of rural locations, “should have

been addressed and adequate reasons given for its

abandonment.” Id. at 48. Because EPA too cavalierly

sidestepped its responsibility to address reasonable alternatives,

its action was not rational and must, therefore, be set aside. See

Allied Local, 215 F.3d at 80; see also Allentown Mack Sales &

Serv., Inc. v. NLRB, 522 U.S. 359, 374 (1998). 

We note that a concern for uniformity did not prevent EPA 10

from establishing a subcategory of stationary engines located in

sparsely populated areas. See 40 C.F.R. § 63.6675. Clearly, a desire

for nationwide uniformity is not always dispositive. 
29

4. FERC Input

An undercurrent coursing through this case has been that,

while EPA justifies the 2013 Rule on the basis of supporting

“system reliability,” 78 Fed. Reg. at 6,679; see also Resp’t Br.

at 29, grid reliability is not a subject of the Clean Air Act and is

not the province of EPA. There is no indication that either

FERC, the federal entity responsible for the reliability of the

electric grid, 16 U.S.C. § 824o(b)(1), or NERC, FERC’s

designated electric reliability organization, see Alcoa, 564 F.3d

at 1345, was involved in this rulemaking or submitted their

views to EPA.

During the comment period, when a commenter suggested

EPA “work with FERC . . . to ensure grid reliability does not

depend on stationary [backup generators],” J.A. 2,594, EPA

responded that the rulemaking’s purpose was to address

emissions from the emergency engines “and to minimize such

pollutants within the Agency’s authority under the CAA. It is

not within the scope of this rulemaking to determine which

resources are used for grid reliability, nor is it the responsibility

of the EPA to decide which type of power is used to address

emergency situations.” J.A. 2,595. Such responsibility was

“within the hands of the power authorities and not” EPA. Id. In

the preamble to the 2013 Rule, EPA similarly stated that

concerns about the impact of demand response in capacity

markets “are comments more appropriately directed towards the

FERC.” 78 Fed. Reg. at 6,685.

But EPA cannot have it both ways—it cannot

simultaneously rely on reliability concerns and then brush off

comments about those concerns as beyond its purview. EPA’s

response to comments suggests that its 100-hour rule, to the

extent that it impacts system reliability, is not “the product of

agency expertise.” State Farm, 463 U.S. at 43.
30

When asked at oral argument where EPA rooted its

authority to regulate engines on the basis of grid reliability,

EPA’s attorney cited 42 U.S.C. § 7412(d), which instructs EPA

to “consider[]” the cost of achieving emission reductions. Id.

§ 7412(d)(2). “Costs” can mean many different things,

including the cost associated with increased risk, but it is unclear

from the record how EPA weighed those costs here, when it

suggested that system reliability was the responsibility of other

specialized agencies but then did not seek input from them. On

remand, we encourage EPA to solicit input from FERC, as

necessary. Cf. Williams Natural Gas Co. v. FERC, 872 F.2d 438,

450-51 (D.C. Cir. 1989) (suggesting agency, on remand, solicit

new comments to obtain needed information).

VI.

We reverse the challenged rules that contain the 100-hour

exemption for operation of emergency engines for purposes of

emergency demand response under the National Emissions

Standards, 40 C.F.R. § 63.6640(f)(2)(ii)-(iii), and the

Performance Standards, 40 C.F.R. §§ 60.4211(f)(2)(ii)-(iii),

60.4243(d)(2)(ii)-(iii). We remand them to EPA for further

action. See 42 U.S.C. § 7607(d)(9); West Virginia, 362 F.3d at

867. The rest of the 2013 Rule remains in effect.

If vacating these portions of the 2013 Rule will cause

administrative or other difficulties, “EPA (or any of the parties

to this proceeding) may file a motion to delay issuance of the

mandate to request either that the current standards remain in

place or that EPA be allowed reasonable time to develop interim

standards.” Cement Kiln Recycling Coal., 255 F.3d at 872; see

also Columbia Falls Aluminum Co. v. EPA, 139 F.3d 914, 924

(D.C. Cir. 1998) (“If EPA wishes to promulgate an interim

treatment standard, the Agency may file a motion in this court

to delay issuance of this mandate in order to allow it a

reasonable time to develop such a standard.”).

So ordered.