NOT FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

CENTER FOR BIOLOGICAL 

DIVERSITY; CENTER FOR 

ENVIRONMENTAL HEALTH, 

Petitioners, 

 v. 

U.S. ENVIRONMENTAL PROTECTION 

AGENCY; MICHAEL S. REGAN,

Administrator, United States Environmental 

Protection Agency, 

Respondents.

No. 20-71196 

EPA No. 

EPA-R09-OAR-2018-0562 

MEMORANDUM*

On Petition for Review of an Order of the

Environmental Protection Agency

Argued and Submitted March 8, 2021

San Francisco, California

Before: WALLACE, GOULD, and FRIEDLAND, Circuit Judges.

The Center for Biological Diversity and the Center for Environmental 

Health (collectively, “Petitioners”) petition for review of a final rule issued by the 

Environmental Protection Agency (“EPA”) that approved a plan to control ozone 

* This disposition is not appropriate for publication and is not precedent 

except as provided by Ninth Circuit Rule 36-3.

FILED

MAR 29 2021

MOLLY C. DWYER, CLERK

U.S. COURT OF APPEALS
2 

emissions in Imperial County, California. We have jurisdiction pursuant to 42 

U.S.C. § 7607(b)(1), and we deny the petition.

Located along the U.S.-Mexico border, Imperial County is home to 

approximately 184,000 people and a thriving agriculture industry. Just across the 

southern border lies Mexicali, Mexico, a major metropolitan area and industrial 

hub with over one million residents. The county and Mexicali share an “airshed,” 

meaning that air pollution is freely and routinely transported between them. 

In 2012, EPA designated Imperial County as a “nonattainment area” under 

the 2008 National Ambient Air Quality Standards (“NAAQS”) for ozone. See 77 

Fed. Reg. 30,088, 30,099 (May 21, 2012). EPA classified the area as “Marginal,” 

or the lowest nonattainment classification level. Id. Consequently, California was 

required to demonstrate—through revisions to its state implementation plan 

(“SIP”) for the 2008 ozone NAAQS—that the county would attain the NAAQS by 

July 20, 2015. In 2016, EPA determined that the county had not attained the 

NAAQS, reclassified the area as the next most serious nonattainment level 

“Moderate,” and required California to formulate a SIP that would attain the 

NAAQS by July 20, 2018. See 81 Fed. Reg. 26,697, 26,698-99 (May 4, 2016). 

California submitted demonstrations indicating that the county would attain 

the NAAQS by the 2018 deadline but for emissions from Mexico, and that EPA 

should therefore approve the state’s plan revisions under the Clean Air Act
3 

section 179B, titled “[i]nternational border areas.” 42 U.S.C. § 7509a(a). Section 

179B contains two relevant provisions. First, section 179B(a) directs EPA to 

approve SIP revisions that meet all applicable statutory requirements except “a 

requirement that such . . . revision demonstrate attainment and maintenance” of the 

NAAQS by the attainment date, so long as EPA determines that the SIP revision 

would be adequate to “attain and maintain” the NAAQS “but for emissions 

emanating from outside of the United States.” Id. § 7509a(a). Second, section 

179B(b) of the Act exempts nonattainment areas from reclassification to a more 

severe category of nonattainment if a state establishes that the area would have 

attained the ozone NAAQS but for international emissions. Id. § 7509a(b). 

California contended that both provisions should be applied to its SIP revisions for

Imperial County. 

On November 1, 2019, EPA issued a proposed rule to approve California’s 

revised SIP submissions for Imperial County under both subsections of 

section 179B(a). See 84 Fed. Reg. 58,641, 58,665 (Nov. 1, 2019).

1

 Under the 

proposed rule, California would keep its “Moderate” nonattainment status, and 

therefore would remain subject to various pollution control requirements. 84 Fed. 

Reg. at 58,641. Petitioners submitted comments arguing, among other things, that 

1 This determination was technically forward looking to the 2018 attainment 

date, but it appears to have been delayed for reasons unrelated to this litigation.
4 

the terms “maintenance” and “maintain” in section 179B(a) require the county to 

demonstrate that the SIP would achieve compliance with the NAAQS beyond the 

attainment date but for international emissions, and that it is not enough to project 

compliance until the attainment date. On February 27, 2020, EPA issued a final 

rule approving California’s revised SIP. See 85 Fed. Reg. 11,817, 11,818-19 (Feb. 

27, 2020). In response to Petitioners’ comments, EPA declined to interpret the 

terms “maintenance” and “maintain” in section 179B(a) and explained that even 

Petitioners’ preferred interpretation would be satisfied by California’s SIP because

extra-record data confirmed that ozone emissions in Imperial County would 

decline until 2030. 85 Fed. Reg. at 11,819-21. This petition for review followed. 

We review EPA’s actions approving or disapproving SIP submissions under 

the “general standard of review for agency actions” set forth in the Administrative 

Procedure Act (“APA”), 5 U.S.C. §§ 701-06. Latino Issues F. v. EPA, 558 F.3d 

936, 941 (9th Cir. 2009). “Under the APA, we consider whether . . . EPA’s action 

was ‘arbitrary, capricious, an abuse of discretion, or otherwise not in accordance 

with law.”’ Id. (quoting 5 U.S.C. § 706(2)(A)). 

1. We need not address Petitioners’ arguments about the proper 

interpretation of the terms “maintain” and “maintenance” in section 179B(a)

because, even assuming Petitioners’ preferred interpretation, EPA’s approval of the 

SIP was not arbitrary, capricious, or an abuse of discretion. 
5 

2. EPA did not violate the APA’s notice requirements by relying on data in 

the final rule that was not cited in the proposed rule. “An agency . . . may use 

‘supplementary data, unavailable during the notice and comment period, that 

expands on and confirms information contained in the proposed rulemaking and 

addresses alleged deficiencies in the pre-existing data, so long as no prejudice is 

shown.’” Kern Cnty. Farm Bureau v. Allen, 450 F.3d 1072, 1076 (9th Cir. 2006) 

(quoting Idaho Farm Bureau Fed’n v. Babbitt, 58 F.3d 1392, 1402 (9th Cir. 

1995)). In the proposed rule, EPA explained that California’s modeling 

sufficiently demonstrated declining ozone emissions in the county, such that 

domestic emissions would fall below the 2008 ozone NAAQS by the 2018 

attainment date. 84 Fed. Reg. at 58,653-55. EPA further noted that other data 

“support[ed] and corroborat[ed] the modeling,” including California’s analyses of 

“long-term downward trends” in Imperial County’s ozone emissions. 84 Fed. Reg. 

at 58,654. EPA’s use of extra-record data to examine emissions further into the 

future in the final rule merely “confirm[ed] and expand[ed] on” the data that 

showed the county’s ozone emissions declining, “providing additional grounds for 

the well-supported conclusions in the [proposed rule].”2 Kern Cnty. Farm Bureau, 

450 F.3d at 1079. 

2 Petitioners have also failed to show prejudice. Although Petitioners allege 

that they would have “disputed the accuracy” of some of the supplemental data on 
6 

3. EPA did not violate section 179B(a) by relying on information that was 

not submitted by California. Nothing in the Clean Air Act or our caselaw indicates 

that EPA must limit its analysis under section 179B(a) to data provided in 

California’s submissions. To the contrary, EPA regulations indicate that the 

agency has broad discretion to determine how best to evaluate section 179B 

demonstrations. See, e.g., 78 Fed. Reg. 34,178, 34,205 (June 6, 2013) (“EPA has 

historically evaluated [section 179B] demonstrations on a case-by-case basis, 

based on the individual circumstances, the classification of the area and the data 

provided by the submitting state.”). 

4. EPA’s approval of the SIP was not arbitrary or capricious. According to 

Petitioners, EPA failed to adequately explain how it could address Imperial 

County’s emissions if they worsen in the future. We reject this argument for two 

reasons. First, EPA discredited Petitioners’ concern by determining that Imperial 

County’s future emissions would continue to decline through 2030. Nothing in the 

record suggests that Imperial County’s domestic emissions will rise vis-à-vis 

Mexico’s, or that Imperial County’s total emissions will rise such that Imperial 

the theory that California undercounts emissions from agricultural soils, Petitioners 

cite no authority to support this allegation. Furthermore, Petitioners do not explain 

why they did not raise such concerns in their comments on the proposed rule, in 

which EPA relied on emissions data submitted by California. Petitioners’ 

allegations are thus too speculative to demonstrate that they were prejudiced by

EPA’s use of extra-record data in the proposed rule. 
7 

County would no longer be able to attain the 2008 NAAQS but for international 

emissions.

Second, EPA correctly noted in the final rule that it may exercise its 

authority to call for plan revisions pursuant to 42 U.S.C. § 7410(k)(5) “if domestic 

emissions were to increase such that the nonattainment problem were to be 

exacerbated.” 85 Fed. Reg. at 11,821. California must continue to collect and 

report air quality monitoring data under existing regulations. See 40 C.F.R. 

§ 58.10 (2020). Using this data, EPA could determine that the SIP for Imperial 

County no longer complies with section 179B, and it could require plan revisions,

as necessary. See Mont. Sulphur & Chem. Co. v. U.S. EPA, 666 F.3d 1174, 1184-

86 & n.3 (9th Cir. 2012). 

Petitioners also argue that EPA’s final rule was arbitrary and capricious 

because EPA failed to explain adequately its reasoning as to the following issues: 

(1) why EPA considered data for PM10 to be an appropriate substitute for ozone 

data; and (2) why additional photochemical modeling and estimations of future 

Mexican emissions should not have been required here. We owe significant 

deference to the agency when reviewing technical analyses. Lands Council v. 

McNair, 629 F.3d 1070, 1074 (9th Cir. 2010). EPA adequately explained its 

reliance on data for PM10 in the final rule, see 85 Fed. Reg. at 11,820, and nothing 

in the law or the administrative record suggests that EPA’s decision not to cite 
8 

additional photochemical modeling or estimations was unreasonable. We therefore 

hold that EPA’s final rule was not arbitrary or capricious. 

PETITION DENIED.