Revised December 31, 2002

UNITED STATES COURT OF APPEALS

For the Fifth Circuit

No. 01-60537

SIERRA CLUB, CLEAN AIR AND WATER INC; COMMUNITY IN-POWERMENT

DEVELOPMENT ASSOCIATION,

Petitioner,

VERSUS

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY; CHRISTINE T.

WHITMAN, ADMINISTRATOR, UNITED STATES ENVIRONMENTAL PROTECTION

AGENCY,

Respondents.

Petition for Review of an Order of the

Environmental Protection Agency

December 11, 2002

Before DeMOSS, STEWART, and DENNIS, Circuit Judges.

DeMOSS, Circuit Judge:

Sierra Club, Inc., Cl ean Air and Water, Inc., and Community

In-Powerment Association (collectively the "Petitioners"), are

appealing the Environmental Protection Agency's (EPA) final action

at 66 Fed. Reg. 26,914 (May 15, 2001) (cod ified at 40 C.F.R. pt.

52), which they contend contravenes the Clean Air Act (CAA), 422

U.S .C. §§ 7401-7671q . The final action approved the State

Implementation Plan (SIP) submitted by the State of Texas for the

Beaumont-Port Arthur (Beaumont) area and extended the ozone

attainment deadline for that area. Petitioners also are appealing

the EPA's determination that no additional co ntrol measures were

required in the Beaumont area to satisfy the statutory requirement

for implementation of Reasonably Available Control Measures (RACM).

The EPA's final action is AFFIRMED in part, REVERSED in part, and

REMANDED.

I. FACTUAL AND PROCEDURAL BACKGROUND

A. Regulatory Background.

The CAA establishes a comprehensive program for improving air

quality throughout the nation. Under the CAA, the EPA is charged

with identifying air pollutants that endanger the public health and

welfare. I d. § 7408. The EPA also is charged with formulating

National Ambient Air Quality Standards (NAAQS), which specify those

pollutants' maximum permissible concentrations in the ambient air.

Id

. § 7409. In 1979, the EPA promulgated a one-hour NAAQS for

ozone, whi ch still remains at 0.12 parts per million based on a

one-hour average. See 40 C.F.R. § 50.9.

Under the CAA, state s must adopt SIPs specifying emission

limitations applicable to pollution sou rces in order to maintain

and enforce each NAAQS. 42 U.S.C. § 7410(a). SIPs are submitted

to the EPA, which may approve, conditionally approve, or disapprove3

th e SIPs in full or in part. I d. § 7410(k). Significantly, the

CAA has a provision that requires SIPs to contain provisions

regulating emissions that "contribute significantly to

nonattainment in, or interfere with maintenance by, any other State

with respect to any such national primary or secondary ambient air

quality standard." I d. § 7410(a)(2)(D)(i)(I). In addition, as

noted in the challenged final action, the EPA has interpreted 42

U.S.C. § 7410(a)(2)(A) as incorporating a similar requirement that

an upwind area be prohibited from contributing signifi cantly to

nonattainment in a downwind area with in the same state. S ee 66

Fed. Reg. 26,917.

Under 42 U.S.C. § 7511a, ozone attainment areas are classified

according to the seve rity of air pollution. The classifications

a re: "marginal," "moderate," "serious," "severe," or "extreme."

42 U.S.C. § 7511a(a)-(e). Each classification has a specified date

for attainment of the ozone NAAQS and the programs that States must

ado pt in their SIPs to attain the NAAQS by reducing emissions of

volatile organic compounds and nitrogen oxides, which are

precursors to the formation of ozone. I d. §§ 7511, 7511a-7511d.

Under the CAA, the following dates were established for the NAAQS

to be achieved: (1) November 15, 1993, for marginal areas; (2)

November 15, 1996, for moderate areas; (3) November 15, 1999, for

serious areas; (4) November 15, 2005, for severe areas; (5)1 Notwithstanding table 1 in 42 U

. S.C. § 7511(a)(1), severe-17

areas have a 1988 ozone design value between 0.190 and 0.280 ppm,

which provides these areas with a different attainment date than

"severe" areas. See id. § 7511(a)(2).

4 November 15, 2007, for severe-17 areas; 1 and (6) November 15, 2010,

for extreme areas. I d. § 7511(a)(1). Under section 7511(a)(5),

the State may apply for two one-year att ainment date extensions

that the EPA can approve if it makes specific determinations

regarding air quality and state compliance with SIP requirements.

In addition, all nonattainment area plans must provide for

implementation of "all reasonably available control measures [RACM]

as expeditiously as practicable." I d. § 7502(c)(1). The EPA must

review each submitted plan. I d. § 7410(k). If the plan is

approved, in whole or in part, the approved provisions become

federally enforceable. I d. §§ 7413, 7604. If the plan is not

approved, or is determined to be incomplete, the State may be

subject to sanctions and eventually federally imposed clean air

measures. Id. §§ 7410(c), 7509.

B. The Extension Policy at Issue in this Case.

On March 25, 1999, the EPA issued a notice of interpretation

of the CAA entitled "Extension of Attainment Dates for Downwind

Transport Areas." 6 4 Fed. Reg. 14,441 (Mar. 25, 1999). In this

extension policy, the EPA interpreted the CAA as allowing for the

extension of attainment dates for ozone nonattainm ent areas

classified as either "moderate" or "serious" and that are downwind5

of areas that transport ozone and interfere with their ability to

attain required ozone levels. I d. at 14,441-42. According to the

EPA, it was seeking to "harmonize the attainment demonstration and

attainment date requi rements for downwind areas affected by

transport both with the graduated attainment da te scheme and the

schedule for achieving reductions in emissions from upwind areas."

Id. at 14,443.

In the extension policy, the EPA explained that an area's

attainment date would be considered for extension if it: (1) has

been identified as a downwind area "affected by transport from

either an upwi nd area in the same State with a later attainment

date or an upwind area in another State that significantly

contrib utes to downwind nonattainment"; (2) has submitted an

approvable attainment demonstration with any "necessary, adopted

local measures," which indicates it will attain the one-hour

NAAQS "no later than the date that the reductions are expected from

upwind areas under the final [nitrogen oxides] SIP Call and/or the

statutory attainment date for upwind nonattainment areas"; (3) has

ado pted "all applicable local measures required under the area's

current classification and any additional measures necessary to

demonstrate attainment," given that the reducti ons occurred as

required in up wind areas; and (4) will "implement all adopted

measures as expeditiously as practicable, but no later than the

date by which the upwind reductions needed for attainment will be6

achieved." Id.

If an area satisfies the above guidelines, it would not be

reclassified or "bumped-up" if it failed to attain by its original

attainment date under section 7511(b)(2). The reasoning for this

is that the EPA concluded that Congress did not intend for downwind

areas to be "penalized by being forced to compensate for

transported pollution by adopting measures that are more costly and

onerous and/or which will become superfluous once upwind areas

reduce their contribution to the pollution problem." I d. a t

14,444. Nevertheless, downwind areas are still responsible for

implementing local controls sufficient to bring about attainment,

except for the transported pollution. Id.

C. EPA's Application of the Extension Policy to the Beaumont

Area.

The Beaumont area is classified as a moderate ozone

nonattainment area. See 40 C.F.R. § 81.344. Therefore, under 42

U.S.C. § 7511(a)(1), its original attainment date was November 15,

1996. However, as a result of the pollution traveling from the

upwind area of Houston/Galveston, the EPA applied its extension

policy that resulted in a new attainment date of November 15, 2007,

for the Beaumont area. This date coincides with the

Houston/Galveston area's November 15, 2 007, attainment date. 6 6

Fed. Reg. 26,914. The EPA established the new attainment date for

the Beaum ont area after concluding that, based on extensive

modeling submitted by the State o f Texas, it will not reach the7

r equired attainment level unless the Houston/Galveston area als o

attains necessary ozone standards. I d. at 26,915-23. In other

words, requiring local reductions in the Beaumont area earlier than

the Houston/Galveston area's attainment date would not accelerate

attainment in the Beaumont area because of the Houston/Galveston

area's pollution contribu tions and the need for upwind emissions

reductions.

Petitioners now appeal the EPA's application of the extension

policy to the Beaumont area. Petitioners also appeal the EPA's

determination t hat 42 U.S.C. § 7502(c)(1) does not compel the

implementation of any additional control measures beyond those

already contained in the Beaumont area's attainment demonstration

SIP.

II. STANDARD OF REVIEW

This Court's role in reviewing the adequacy of the EPA's final

action is governed by the Administrative Procedure Act, 5 U.S.C. §

706. Section 706(2) provides that a reviewing court shall "hold

unlawful a nd set aside agency action, findings, and conclusions

found to be--(A) arbitrary, capricious, an abuse of discretion, or

otherwise not in accordance with law." S ee also Texas Off ice of

Pub. Util. Counsel v. Federal Communications Comm'n

, 265 F.3d 313,

320 (5th Cir. 2001); Macktal v. United States Dep't of Labor

, 171

F.3d 323, 326 (5th Cir. 1999).

III. DISCUSSION8

A. Whether the EPA acted consistently with the CAA in granting an

extension of the statutory date for meeting federal standards

for ozone air pollution in the Beaumont area and in approving

a SIP for the area based on that extension.

The EPA argues that it did not abuse its authority by

im plementing its extension policy. The EPA asserts that its

interpretation of the CAA is the best wa y to reconcile the Act's

provisions. According to the EPA, when considering all of the

CAA's pertinent language, Congress clearly did not intend the

unduly restrictive and punitive readin g that Petitioners urge on

this Court. The EPA argues that its interpretation of the CAA was

necessary t o fill a statutory gap to avoid unfairly burdening

downwind areas by forcin g them to adopt more stringent local

controls for the purpose of compensating for another area's

transported pollution.

In support of its argument, the EPA notes that Congress has

provided extensions to transport-affected nonattainment areas such

as in cases of international border areas under section 7509a,

which spares ozone nonattainment areas that demonstrate they suffer

frompollution from “outside of the United States” from being

bu mped-up to a higher ozone classification. Under section

7511a(h), the CAA authorizes the EPA to designate certain isolated

ozone nonattainment areas as “rural transport areas,” which allows

them to be subjected to less stringent control requirements. In

addition, 42 U.S.C. § 7511a(j)(2) provides that when a multi-state

nonatta inment area fails to demonstrate attainment by the9

applicable deadline, a State within that area may be relieved of

statutory sanctions if “the State would have been able to make such

demonstration but for the failure of one or more other States”

within the control area. Section 7511(a)(4) of the United States

Code authorizes the adjustment of an area's original classification

based on factors including transpor ted pollution. Furthermore,

under 42 U.S.C. § 7410(a)(2)(D)(i)(I), SIPs must contain adequate

provisions prohibiting pollution that “contribute[s] significantly

to nonattainment in . . . any other State.” And, section 7426

provides States the opportunity to petition the EPA for relief from

interstate pollution.

The EPA concedes that when the 1990 amendments to the CAA were

passed, Congress did not expressly specify similar relief for other

a reas, including for downwind cities that are unable to achieve

attainment as a result of upwind cities within the same State. The

EPA, however, maintains that Congress did not fully address all

issues of ozone transport at the time the CAA was amended in 1990

because there was a lack of understanding conce rning the issue.

According to the EPA, it was not until the mid-1990s that a

suffici ent understanding of the complex ozone transport problem

began to be achieved as a result of the Ozone Transport Assessment

Group (OTAG), an organization with the missio n to assess and

recommend strategies to address ozone transport. Thus, the EPA

insists that a reasonable understanding of ozone transport was not

achieved until well after the Beaumont area's 1996 attainment10

deadline. Ultimately, the EPA asserts that it was reasonable for

it to conclude that the Houston/Galveston area's impact on the

Beaumont area's ability to attain the one-hour ozone standard

indicated that the CAA's transport and attainment provisions did

not function as Congress envisioned.

Petitioners, however, contend the EPA abused its authority by

defeating the express statutory reclassification requirements of

t he CAA and extending the ozone attainment deadlines for the

Beaumont area b ased on pollution transport, and by approving the

SIP as adequate based on the extension. According to Petitioners,

because the Beaumont area failed to achieve attainment of required

ozone l evels, it should have been reclassified from “moderate”

(with an attainment date of November 15, 1996) to either “serious”

(with an attainment date of November 15, 1999) or “severe” (with an

attainment date of November 15, 2005). S ee 42 U.S.C. § 7511a.

Petitioners further maintain that under the CAA, reclassification

would require that an incremental increase in the mandatory control

strategies be imposed on the Beaumont area's SIP in exchange for

any extended attainment date. S ee 42 U.S.C. §§ 7511a(1)-(d) and

7511(b)(2)(A)).

This Court is guided by Chevron, U.S.A., Inc. v. NRDC

, 467

U.S. 837, 842-44 (1984), in evaluating the EPA's interpretation of

the CAA. The first step under C hevron is to inquire w hether

Congress “has directly spoken t o the precise question at issue.”11

Id. at 842-43. If Congress has spoken to the issue, this Court

“ must give effect to the unambiguously expressed intent o f

Congress” and "that is the end of the matter." I d. However, if

the statute is “silent or ambiguous with respect to the specific

issue,” this Court must move to Chevron' s second step. I d. at 843.

Under the second step, this Court must defer to the EPA's

interpretation if it is “based on a permissible construction of the

statute.” I d. Furthermore, as this Court has stated, the EPA's

decision will be reversed “only if it was arbitrary, capricious or

manifestly contrary to the statute.” T exas Office of Pub. Util.

Counsel, 265 F .3d at 320 (citing C hevron

, 467 U.S. at 844). S ee

also 5 U.S.C. § 706(2).

Petitioners correctly point out that the Supreme Cour t has

stated: “[I]t is generally presumed that Congress acts

intentionally and purposely when it includes particular language in

one section of a statute but omits it in another.” C ity of Chicago

v. Environmental Defense Fund, 511 U.S. 328, 338 (1994) (internal

quotations omitted). Petitioners contend that the CAA's numerous

provisions addressing the issue of pollution transport and

extensions of attainment dates clearly indicates that Congress

fully understood the issue at hand and intended not to authorize

the EPA to extend attainment dates as it did in this case.

Petitioners conclude, therefore, that under step one of C hevron

,

the question of whether an attainment date extension is permissible12

based on air pollution transport has been resolved by the statute

and “that is the end of the matter.” C hevron, 467 U.S. at 842-43.

We agree with the Petitioners. The plain terms of the CAA

precl ude an extension of the sort the EPA granted in the present

case. As the Petitioners correctly point out, the CAA specifies

when the EPA may extend attainment deadlines to account for upwind

emissions that jeopardize an area's ability to achieve attainment

without requiring reclassification of the area. For example, the

CAA provides:

an y State that establishes to the satisfaction of the

Administrator that . . . such State would have attained

the national ambient air quality standard for ozone by

the applicable attainment date, but for emissions

emanating from outside of the United States, shall not be

subject to the provisions of section 7511(a)(2) or (5) of

this title or section 7511d of this title.

42 U.S.C. § 7509a(b) (emphasis added). Furthermore, the CAA

provides for certai n nonattainment areas to be exempted from the

attai nment deadlines by authorizing the EPA to designate those

areas as "rural transport areas," which allow those areas to be

treated as "marginal" areas. Id. § 7511a(h). This designation,

however, is limited to a transport- affected area that "does not

include, and is not adjacent to, any part of a Metropolitan

Statistical Area or, where one exists, a Consolidated Metropolitan

Statistical Area," id. § 7511a(h)(1), and whose Oxides of Nitrogen

emissions "do not make a significant contribution to the ozone

concentrations measured in the area or in other areas." Id. §13

7511a(h)( 2). As the D.C. Circuit aptly stated in a recent case

similar to this one: "We cannot but infer from the presence of

these specific exemptions that the absence of any other exemption

for the transport of ozone was deliberate, and the Agency's attempt

to grant such a dispensation is contrary to the intent of

Congress." S ierra Club v. EPA

, 294 F.3d 155, 160 (D.C. Cir. 2002).

See also

, S ierra Club v. EPA

, 2002 WL 31641639, at *6 (7th Cir.,

Nov. 25, 2002).

We note that NRDC, upon which the EPA heavily relies, is

inapposite to the prese nt case. In N RDC, the D.C. Circuit

affirmed the EPA’s grant of two deadline extensions. The first

deadline extension concerned the submission of enhanced Inspection

and Maintenance (I/M) SIPs. N RDC, 22 F.3d at 1135. Under the CAA,

Congress provided that States be given a one-year period after

guidance promulgation to bring their SIPs into compliance with the

enhanced I/M performance standard. I d. However, the EPA failed to

meet its November 15, 1991, deadline for providing guidance, which

"made it impossible for stat es both to have the benefit of this

lead time and to meet their November 15, 1993, enhanced I/M

submission deadline." Id. The court noted that "[w]hile the CAA

is very specific about the consequences of a state's failure to

meet the submittal deadline, the Act is silent on what should occur

if the agency misses its guidance deadline." I d. Because

Congress' statutory scheme provided that the States "comply in all14

respects" with the EPA guidance, the court concluded that a

deadline extension was necessary for the States to have a full year

to do so. Id.

T he second deadline extension in NRDC concerned the CAA' s

requirement that States encompassing nonattainment areas submit

SIPs or SIP revisions addressing the application of Reasonably

Available Control Technology (RACT) to stationary emission sources

of nitrogen oxides by November 15, 1992. I d. However, the EPA

concluded that photochemical grid modeling was "the only reliable

tool to justify an area wide exemption from the [nitrogen oxides]

requirements." I d. at 1136. Moreover, the EPA found that the

modeling "ha[d] not been utilized previously or, if utilized, ha[d]

not adequately considered the effects of [nitrogen oxides]

emissions reductions." Id. As a result, the EPA determined that

"the time needed to establish and implement a modeling protocol and

to interpret the model results will, in a variety of cases, extend

beyond the November 15, 1992 deadline for submission of [nitrogen

oxides] rules." I d. Therefore, the EPA created a narrow one-year

extension for nitrogen oxide s RACT submissions limited to

situations in which a State is able to document that "(1) credible

photochemical grid modeling is not available or did n ot consider

the effects of [nitrogen oxides] reductions and (2) the state

submits progress reports on the modeling showing the program is on

schedule while the committal SIP is being reviewed by EPA." Id.15

When evaluating the validity of th e extension, the D.C.

Circuit noted that the CAA expressly gave the EPA 14 to 18 months

after the submittal deadline to approve or disapprove these SIPs

and to determine whether a State qualified for certain exemptions.

Id. at 1136. The court further noted that only a single nitrogen

oxides RACT submission was required under the CAA and, therefore,

Congress intended all d ata supporting exemptions to be included

with that submittal. I d. According to the court, after receiving

a submittal, the EPA should then have had the full 14 to 18 months

to review it before making an exemption determination. I d. The

court, however, noted that in many instances the EPA would not be

able to utilize the full statutory review time to make an exemption

determination before the statutory deadline. Therefore, the court

concluded that "had Congress foreseen the exemption timing problem,

a matter outside the EPA's control, it would have elected to accord

the EPA the full statutory review time." Id.

As discussed above, the first extension upheld by the D.C.

Circuit in NRDC was necessary to correct a timing problem created

by the EPA because it did not meet its own guidance deadline. The

second extension was upheld because the EPA w ould not otherwise

have the full review time in which to make adequate exemption

determinatio ns. Ultimately, this second extension was made

necessary by the EPA's own finding that photochemical grid modeling

was necessary to justify area wide exemptions. Therefore, in both16

instances, the extensions upheld by the D.C. Circuit were made

necessary by the EPA's own action or inaction, which could not have

been foreseen by Congress when it enacted the 1990 revision of the

CAA. Neither extension, however, had anything to do with a

situation in which a nonattainment area submitted a SIP, had it

approved by the EPA, implemented the SIP, and then failed to meet

its attainment deadline as did the Beaumont area in this case.

B. Whether the EPA reasonably interpreted the CAA as not

requiring any additional RACMs in the Beaumont area’s SIP.

Section 7 502(c)(1) of the CAA requires that plans for

nonattainment areas “shall provide for the implement ation of all

reasonably available control measures as expeditiously as

practicable

. . . and shall provide for attainment of the national

primary ambient air quality standards.” 4 2 U.S.C. § 7502(c)(1)

.

Petition e rs contend that the EPA arbitrarily and capriciously

rejec ted a number of control measures that are demonstrably

reasonably available for use in the Beaumont area. As a result,

Petitioners argue that the EPA's final action conflicts with the

plain language of section 7502(c)(1).

Specifically, Petitioners assert that the EPA improperly

limited the menu of RACMs to those that would advance the date of

attainment. Petitioners insist the result of the EPA's action

relegates the CAA's RACM mandate to mer e surplusage because

additional c ontrol measures that could reduce the frequency and

severity of violations need not be considered. Included in the17

RACMs that Petitioners claim have been excluded from consideration

are a number of transport control measures (TCM) listed in section

7408(f) of the CAA. In addition, Petitioners contend that the

EPA's determination that potential measures requiring intensive and

costly implementation efforts are not R ACMs. Petitioners assert

that such a determination is based on vague and unintelligible

standards and, therefore, is unreasonable.

The EPA ackno wledges that additional control measures are

available to the Beaumont area. The EPA, however, contends that

the Beaumont area's attainment demonstration contained al l RACMs

required under the CAA. Significantly, the EPA has interpreted

section 7502(c)(1) as imposing a dut y to implement only those

control measures that contribute to attainment as expeditiously as

practicable. S ee ; 57 Fed. Reg. 13,498

, 13,560 (Apr. 16, 1992)

(citing 44 Fed. Reg. at 20,375).

Furthermore, the EPA notes that it revised its guidelines

concerning TCMs in its General Preamble for Implementation for the

Clean Air Act Amendments of 1990 (Apr. 16, 1992) in which it

concluded that "based on experience with implementing TCMs over the

years, EPA now believes that local circumstances vary to such a

degree from city-to-city that it is inappropriate to presume that

all [section 7408(f)] measu res are reasonably available in all

areas." 5 7 Fed. Reg. at 13,560

. The EPA then concluded that only

those TCMs that are determined to be "reasonably available for18

implementation in the area in light of local circumstances" should

be reviewed by the planning agency. Id.

As noted above, the EPA determined that only th ose control

measures that contribute to attainment as expeditiously as

practicable are required. This interpretation of the CAA was

applied in a number of final actions before the statute was amended

in 1990. S ee 53 Fed. Reg. 30,220, 30,222 (Aug. 10, 1988); 53 Fed.

Reg. 30,224, 30,234 (Aug. 10, 1988); 55 Fed. Reg. 40,658, 40,659

(Oct. 4, 1990). When Congress amended the CAA, it moved the RACM

requirement from section 7502(b)(2) to section 7502(c)(1). At the

same time, Congress created a new section to the Act that preserved

all existing EPA guidance issued prior to the amendments. See 42

U.S.C. § 7515. Therefore, we conclude that Congress intended to

preserve the EPA's interpretation of the CAA regarding the RACM

requirement.

Furthermore, there is persuasive authority from the Ninth

Circui t to support the EPA's interpretation of the RACM

requirement. In O ber v. Whitman

, the Ninth Circuit upheld the

EPA’s in terpretation of the corresponding RACM requirements for

particulate matter (PM-10) governed by section 7513a(a). 243 F.3d

1190 (9th Cir. 2001). There, the plaintiffs challenged the

exemption from control of a variety of sou rces of particulate

pollution in a Federal Implementation Plan for the Phoenix area.

The Ninth Circuit concluded that the CAA allowed the EPA to19

make what it called " de minimis " exemptions and that the agency

acted permissibly in designating some pollution sources as de

minimis

. I d

. at 1198. Notably, the court accepted the EPA's

reasoning in the General Preamble for the Implementation of Title

I of the Clean Air Act Amendments of 1990 that control measures not

aiding in achieving attainment may be excluded from further

consideration because they would not represent RACM for that area.

Id. at 1194-95, 1198. The same reasoning used by the EPA in Ober

also was used here. The EPA concluded that section 7502(c)(1) does

not require the implementation of RACMs that do not aid in

achieving attainment o f national clean air standards as

expeditiously as practicable. Implementing such RACMs would be a

pointless expendi ture of effort, which courts are reluctant to

require. S ee, e.g., Alabama Power Co. v. Costle

, 636 F.2d 323, 360

(D.C. Cir. 1980).

Similarly, the EPA need not require an analysis of all

transport control measures (TCM) specifically listed in 42 U.S.C.

§ 7408(f). TCMs are measures taken to reduce emissions of ozone

precursors emitted by transportation sources. We conclude that it

would not be possible to assess all available measures and consider

the effects of such measures in every possible combination, as

Petitioners argue is required by the statute. Furthermore, the EPA

has recognized that only some TCMs "will be reasonably available

for implementation in many nonattainment areas." 57 Fed. Reg. at20

13,560.

Nevertheless, the EPA did conclude that it would be reasonable

to use a midpoint level of program effectiveness to analyze

potential reductions from TCMs, a level that would be economically

feasible and provide effective implementation. S ee 66 Fed. Reg. at

26,932. Under this program, the EPA’s analysis adequately assessed

all necessary TCMs for effectiveness. The result confirmed that

the TCMs would not produce emission reductions sufficient to

advance attainment in the Beaumont area. Therefore, it appears

that the EPA properly concluded that no a dditional TCMs were

required because they would not contribute to expediti ous

attainment.

Moreover, the EPA properly concluded that potential measures

requiring intensive and costly implementation were not RACMs

because they could not be readily implemented due to excessive

administrative burden or local conditions such as high costs. I d.

at 26,929. Such determinations based on a cost/benefit analysis

are within the EPA’s discretion unless the statutory scheme

precludes such a determination. S ee, e.g., Michigan v. EPA

, 213

F.3d 663, 678-79 (D.C. Cir. 2000); Cf. 42 U.S.C.A. § 7409(b)(1)

(prohibiting a co st/benefit analysis by preventing the EPA from

considering any factor other than health effects relating to

pollutants in the air in establishing NAAQS for ozone and

particulate matter). We find no such limitation in the CAA.21

Last ly, we note that the D.C. Circuit's decision in S ierra

Club v. EPA also supports our rejection of the Petitioners'

argument that treating as potential RACMs only those measures that

would advance the date at which an area reach es attainment

conflicts with the CAA's text and purpose and lacks any rational

basis. See 294 F.3d at 162. As the D.C. Circuit concluded:

The Act, on its face, neither elaborates upon which

control measures shall be deemed "reasonably available,"

nor compels a state to consider whether a ny measure is

"reasonably available" without regard to whether it would

expedite attainment in the relevant area. Further, the

EPA reasonably concluded that because the Act "use[s] the

same terminology in conjunction with the RACM

requirement" as it does in requiring timely attainment,

compare 42 U.S.C. § 7502(c)(1) (requiring implementation

of RACM "as expedit iously as practicable but no later

than" the applicable a ttainment deadline), w ith id. §

7511(a)(1) (requiring attainment under same constraints),

the RACM requirement is to be understood as a means of

meeting the deadline for attainment, Approval, 66 Fed.

Reg. at 610/2. Because the statutory provision is

ambiguous and the EPA's construction of the term "RACM"

is reasonable, we defer to the Agency. See Chevron, 467

U.S. at 843, 104 S. Ct. at 2781-82.

Id. However, though our opinion defers to the E PA in exempting

certain proposed RACMs from the requirements of the CAA, we must

impress upon the EPA that it has a duty to: (1) demonstrate that

it has examined relevant data, and (2) provide a satisfactory

explanation for its rejection of those proposed RACMs and why they,

individually and in combination, would not advance the Beaumont

area's attainment date. S ee Ober

, 243 F.3d at 1195 (quoting

American Lung Ass'n v. EPA , 134 F.3d 388, 392-93 (D.C. Cir. 1998)

( "[U]nless [EPA] describes the standard under which [it] has22

arrived at this conclusion, supported by a plausible explanation,

we have no basis for exercising our responsibility t o determine

whether [EPA's] decision is arbitrary, capric ious, an abuse of

discretion or otherwise not in accordance with law. . . .")).

CONCLUSION

Accordingly, we REVERSE the portion of the EPA's final action

at 66 Fed. Reg 26,914 (May 15, 2001) granting the Beaumont area an

extension of its attainment date. However, we AFFIRM the portion

of the EPA's final action that treats as potential RACMs only those

measures that would advance the attainment date and considers

implementation costs when rejecting certain control measures. We

REMAND this case to the EPA for proceedings consistent with this

opinion. On R EMAND , the EPA must describe the standard under

which it has rejected certain proposed RACMs supported by a

plausible explanation.

AFFIRMED in part, REVERSED in part, and REMANDED.23