                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


CENTER FOR BIOLOGICAL                   No. 14-15836
DIVERSITY; SIERRA CLUB; PUBLIC
EMPLOYEES FOR ENVIRONMENTAL                D.C. No.
RESPONSIBILITY; DESERT                 3:03-cv-02509-SI
SURVIVORS,
              Plaintiffs-Appellants,
                                          OPINION
                 v.

BUREAU OF LAND MANAGEMENT;
U.S. FISH & WILDLIFE SERVICE,
             Defendants-Appellees,

                and

BLUERIBBON COALITION;
CALIFORNIA ASSOCIATION OF 4
WHEEL DRIVE CLUBS; SAN DIEGO
OFF ROAD COALITION; DESERT
VIPERS MOTORCYCLE CLUB; HIGH
DESERT MULTIPLE USE COALITION;
AMERICAN MOTORCYCLE
ASSOCIATION, DISTRICT 37; OFF-
ROAD BUSINESS ASSOCIATION;
CALIFORNIA OFF-ROAD VEHICLE
ASSOCIATION; AMERICAN SAND
ASSOCIATION,
  Intervenor-Defendants-Appellees.
2              CTR. FOR BIO. DIVERSITY V. BLM

        Appeal from the United States District Court
           for the Northern District of California
        Susan Illston, Senior District Judge, Presiding

             Argued and Submitted April 14, 2016
                  San Francisco, California

                      Filed August 15, 2016

    Before: Diarmuid F. O’Scannlain, Richard R. Clifton,
            and N. Randy Smith, Circuit Judges.

                 Opinion by Judge O’Scannlain


                           SUMMARY*


                       Environmental Law

    The panel affirmed the district court’s judgment in favor
of the Bureau of Land Management (“BLM”) in an action by
plaintiff environmental groups challenging BLM’s proposal
to expand access for off-road vehicle recreation in the
Imperial Sand Dunes Special Recreation Management Area
in Imperial County, California.

    The Dunes contain a species of plant known as the
Peirson’s milkvetch that is categorized as a “threatened
species” under the Endangered Species Act. In 2013, BLM
adopted a new Recreation Area Management Plan under

  *
    This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
             CTR. FOR BIO. DIVERSITY V. BLM                 3

which a tract would remain closed to off-road vehicle use, as
would 9,261 acres of milkvetch critical habitat, and the
remainder of the Dunes would be open to off-road vehicle
use. Pursuant to section 7(a)(2) of the Endangered Species
Act, BLM consulted with the United States Fish and Wildlife
Service, which issued a Biological Opinion finding that the
2013 Recreation Area Management Plan was not likely to
jeopardize the continued existence of the milkvetch or the
desert tortoise.

    The panel held that the Endangered Species Act did not
require the Biological Opinion to contain Incidental Take
Statements for threatened plants, such as the milkvetch.

    The panel rejected plaintiffs’ claims that BLM’s decision
to open additional land to off-road vehicle use violated the
Clean Air Act, the Federal Land Policy and Management
Act, the National Environmental Policy Act, and the
Administrative Procedure Act. The panel held that the BLM
did not act arbitrarily or capriciously when it relied on air
quality analysis demonstrating that emissions resulting from
visitors to the Dunes would not be increased impermissibly
by the land openings.


                        COUNSEL

Brendan R. Cummings (argued), Center for Biological
Diversity, Joshua Tree, California; Sarah Uhlemann, Center
for Biological Diversity, Seattle, Washington; for Plaintiffs-
Appellants.

Brian C. Toth (argued), Norman L. Rave, Jr., and Kevin W.
McArdle, Attorneys; Sam Hirsch, Acting Assistant Attorney
4            CTR. FOR BIO. DIVERSITY V. BLM

General; Environment & Natural Resources Division, United
States Department of Justice, Washington, D.C.; Cheryll
Dobson and Erica Niebauer, United States Department of the
Interior, Office of the Solicitor; for Defendants-Appellees.

David P. Hubbard (argued), Gatzke Dillon & Ballance LLP,
Carlsbad, California; Paul A. Turcke (argued), Moore Smith
Buxton & Turcke, Boise, Idaho; Dennis L. Porter,
Sacramento, California; for Intervenors-Defendants-
Appellees.


                        OPINION

O’SCANNLAIN, Circuit Judge:

    We must decide whether the United States Fish and
Wildlife Service, in reviewing the Bureau of Land
Management’s proposal to expand access for off-road vehicle
recreation in the Imperial Sand Dunes Special Recreation
Management Area, has complied with the requirements of the
Endangered Species Act.

                              I

    Just north of the Mexican border, in Imperial County,
California, lies the Imperial Sand Dunes Planning Area, a
227,000-acre tract of desert, 214,930 acres of which is
managed by the Bureau of Land Management (“BLM”). The
expanse is home to the Algodones Dunes, the largest active
sand dune system in the United States. A 138,111-acre
portion of the Planning Area, designated as the Imperial Sand
Dunes Special Recreation Management Area, is set aside for
the protection of plants and wildlife, as well as for outdoor
              CTR. FOR BIO. DIVERSITY V. BLM                      5

recreation. The Dunes consistently attract well over one
million visitors annually, particularly off-road vehicle
enthusiasts who flock to the area to take advantage of the
unique terrain and beautiful landscape.1

    The current litigation, which has been ongoing for over a
decade, originates from BLM’s decision to reopen land
within the Imperial Sand Dunes Special Recreation
Management Area to off-road vehicle use. The Dunes contain
a species of purple-flowered plant known as the Peirson’s
milkvetch (Astragalus magdalenae var. peirsonii),
categorized as a “threatened species” for purposes of the
Endangered Species Act. Ctr. for Biological Diversity v.
Bureau of Land Mgmt., 422 F. Supp. 2d 1115, 1124–25 (N.D.
Cal. 2006). In 2000, the Center for Biological Diversity (“the
Center”) sued BLM, claiming that it had violated the
Endangered Species Act by failing to enter into formal
consultation with the Fish and Wildlife Service before
adopting a management plan for the Dunes. Id. at 1123. As a
result, BLM agreed to close temporarily portions of the
Dunes to off-road vehicles until it could implement a new
Recreation Area Management Plan (“RAMP”). Id. at 1124. In
2005, the Center successfully challenged a BLM plan to
reopen the closed areas. Id. at 1121. The District Court for the
Northern District of California at that time held, inter alia,
that the Fish and Wildlife Service’s “Biological Opinion” for
a 2003 BLM RAMP violated the Endangered Species Act in
several respects relating to its evaluation of the potential
impact on the Peirson’s milkvetch and the desert tortoise,
another threatened species. Id. at 1121–22.


  1
    A 26,098-acre tract within the Planning Area, known as the North
Algodones Dunes Wilderness, is permanently off-limits to off-road
vehicle recreation.
6            CTR. FOR BIO. DIVERSITY V. BLM

    In response to the court’s order, the Fish and Wildlife
Service issued a new critical habitat designation for the
milkvetch in 2008, which the Center unsuccessfully
challenged. In 2013, BLM adopted a new RAMP. Under the
new plan, the 26,098-acre North Algodones Dunes
Wilderness tract would remain closed to off-road vehicles, as
would 9,261 acres of milkvetch critical habitat. The
remainder of the Imperial Sand Dunes Special Recreation
Management Area—over 127,000 acres—would be open to
off-road vehicle use. BLM additionally prepared an
Environmental Impact Statement analyzing the 2013 RAMP,
and consulted with the Fish and Wildlife Service pursuant to
section 7(a)(2) of the Endangered Species Act. As a result,
the Fish and Wildlife Service issued a new Biological
Opinion finding that the 2013 RAMP was not likely to
jeopardize the continued existence of the milkvetch or desert
tortoise.

    The Center once again mounted a challenge, asserting
various claims under the Endangered Species Act, 16 U.S.C.
§§ 1531 et seq., the Clean Air Act, 42 U.S.C. §§ 7401 et seq.,
the Federal Land Policy and Management Act, 43 U.S.C.
§§ 1701–1785, the National Environmental Policy Act,
42 U.S.C. §§ 4321 et seq., and the Administrative Procedure
Act, 5 U.S.C. §§ 706 et seq. Specifically, the Center alleged
that: 1) the 2012 Biological Opinion was deficient because it
did not include an Incidental Take Statement for the Peirson’s
milkvetch; 2) the Fish and Wildlife Service had unreasonably
delayed issuance of a recovery plan for the Peirson’s
milkvetch under section 4(f) of the Endangered Species Act;
3) the 2013 Environmental Impact Statement violated the
National Environmental Policy Act by failing to take a “hard
look” at impacts on wilderness areas; and 4) BLM violated
the Clean Air Act, the Federal Land Policy and Management
               CTR. FOR BIO. DIVERSITY V. BLM                         7

Act, the National Environmental Policy Act, and the
Administrative Procedure Act by failing to evaluate properly
the impacts of the 2013 RAMP on air quality.

   The District Court for the Northern District of California
granted summary judgment in favor of BLM on all but the
second issue.2

    The Center timely appealed and argues that the plain
language of the Endangered Species Act requires an
Incidental Take Statement for plants rather than for just fish
and wildlife. The Center additionally renews its claim that
BLM failed to comply with the Clean Air Act, the Federal
Land Policy and Management Act, the National
Environmental Policy Act, and the Administrative Procedure
Act by failing to evaluate properly the impacts of the 2013
RAMP on air quality.

                                   II

   The Center first avers that the Endangered Species Act
requires Fish and Wildlife Service Biological Opinions to
contain Incidental Take Statements for threatened plants. In
contrast, BLM maintains that Incidental Take Statements are
required solely for fish and wildlife.

    We review an agency’s interpretation of a statute it is
charged with administering under the two-step framework set
forth in Chevron, U.S.A., Inc. v. Natural Resources Defense
Council, Inc., 467 U.S. 837 (1984). Ctr. for Biological
Diversity v. Salazar, 695 F.3d 893, 902 (9th Cir. 2012). We

  2
    BLM does not challenge on appeal the district court’s disposition of
this issue in favor of the Center.
8             CTR. FOR BIO. DIVERSITY V. BLM

must first determine whether “Congress has directly spoken
to the precise question at issue. If the intent of Congress is
clear, that is the end of the matter; for the court, as well as the
agency, must give effect to the unambiguously expressed
intent of Congress.” Chevron, 467 U.S. at 842–43. “[I]f the
statute is silent or ambiguous with respect to the specific
issue,” however, “the question for the court is whether the
agency’s answer is based on a permissible construction of the
statute.” Id. at 843. “If a statute is ambiguous, and if the
implementing agency’s construction is reasonable, Chevron
requires a federal court to accept the agency’s construction of
the statute, even if the agency’s reading differs from what the
court believes is the best statutory interpretation.” Ctr. for
Biological Diversity, 695 F.3d at 902 (quoting Nat’l Cable &
Telecomm. Ass’n v. Brand X Internet Servs., 545 U.S. 967,
980 (2005)).

                                A

    Enacted in 1973, the Endangered Species Act authorizes
the Secretary of the Interior to designate certain species as
“endangered” or “threatened.” Babbitt v. Sweet Home
Chapter of Cmtys. for a Great Or., 515 U.S. 687, 690 (1995).
Section 9(a)(1) of the Act provides, among others, the
following protection for species so designated: “[W]ith
respect to any endangered species of fish or wildlife listed
pursuant to section 1533 of this title it is unlawful for any
person subject to the jurisdiction of the United States to . . .
take any such species within the United States or the
territorial sea of the United States.” 16 U.S.C.
§ 1538(a)(1)(B). The Act defines “take” as “to harass, harm,
pursue, hunt, shoot, wound, kill, trap, capture, or collect, or
to attempt to engage in any such conduct.” 16 U.S.C.
§ 1532(19). Section 9(a)(2) lists separate protections for
              CTR. FOR BIO. DIVERSITY V. BLM                    9

endangered or threatened plants, but notably does not use the
term “take.” See 16 U.S.C. § 1538(a)(2).

     In 1978, Congress added a provision to the Act requiring
federal agencies wishing to engage in action that may
adversely affect an endangered or threatened species to
consult first with the Secretary of the Interior to “insure that
any action authorized, funded, or carried out by such agency
. . . does not jeopardize the continued existence of any
endangered species or threatened species or result in the
destruction or adverse modification of habitat of such
species.” Pub. L. 95-632, § 3, 92 Stat. 3751, 3752 (codified
as amended at 16 U.S.C. § 1536(a)(2)). Consultation results
in a “Biological Opinion, summarizing the relevant findings
and determining whether the proposed action is likely to
jeopardize the continued existence of the species.” Ariz.
Cattle Growers’ Ass’n v. U.S. Fish & Wildlife, 273 F.3d
1229, 1239 (9th Cir. 2001) (citing 16 U.S.C. § 1536(b)). In
1982, Congress amended section 7 (as well as section 10) of
the Act, adding provisions governing “incidental taking,”
which are takings that are “incidental to, and not the purpose
of, the carrying out of an otherwise lawful activity.” See Pub.
L. 97-304, §§ 4(a), 6(1), 96 Stat. 1411, 1418, 1422 to 1423;
Sweet Home, 515 U.S. at 729. Under the amended version of
section 7, the Fish and Wildlife Service “must issue an
Incidental Take Statement if the [Biological Opinion]
concludes no jeopardy to listed species or adverse
modification of critical habitat will result from the proposed
action, but the action is likely to result in incidental takings.”
Or. Nat. Res. Council v. Allen, 476 F.3d 1031, 1036 (9th Cir.
2007). The statute requires BLM to issue an “Incidental Take
Statement” that:
10           CTR. FOR BIO. DIVERSITY V. BLM

       (i) specifies the impact of such incidental
       taking on the species,

       (ii) specifies those reasonable and prudent
       measures that the Secretary considers
       necessary or appropriate to minimize such
       impact,

       (iii)   in the case of marine mammals,
       specifies those measures that are necessary to
       comply with section 1371(a)(5) of this title
       with regard to such taking, and

       (iv)    sets forth the terms and conditions
       (including, but not limited to, reporting
       requirements) that must be complied with by
       the Federal agency or applicant (if any), or
       both, to implement the measures specified
       under clauses (ii) and (iii).

16 U.S.C. § 1536(b)(4)(C).

    Here, though the Fish and Wildlife Service’s 2012
Biological Opinion found that off-road vehicle use “could
result in direct death or injury of Peirson’s milk-vetch due to
crushing, uprooting, or burial of plants and seeds, and by
reducing reproductive output of those that survive,” the
Service did not issue an Incidental Take Statement for the
plant.

                              B

    The Center argues that the plain language of section 7’s
Incidental Take Statement provision requires Incidental Take
             CTR. FOR BIO. DIVERSITY V. BLM                 11

Statements for both plants and animals. As the Center
observes, consultation between the Fish and Wildlife Service
and BLM is required for “any endangered species or
threatened species.” 16 U.S.C. § 1536(a)(2) (emphasis
added). This is why the resulting Biological Opinion included
an analysis of the impact of off-road vehicles on the
milkvetch. Under the statute, when the Fish and Wildlife
Service concludes in its Biological Opinion that “the taking
of an endangered species or a threatened species incidental to
the agency action will not” jeopardize the continued existence
of a species, but will nevertheless adversely impact a species,
it must issue a statement that “specifies the impact of such
incidental taking on the species.” 16 U.S.C. § 1536(b)(4). The
Center contends that the use of the term “species,” rather than
a different term that might restrict the provision to fish or
wildlife, signifies that an Incidental Take Statement is
required for all species, including plants.

    When one reads section 7 in isolation, the Center’s
argument seems plausible. Indeed, there is nothing
specifically in that provision to indicate that Congress
intended to limit the term “species” to fish or wildlife.
Section 7, however, “must be read in [its] context and with a
view to [its] place in the overall statutory scheme,” Food &
Drug Admin. v. Brown & Williamson Tobacco Corp.,
529 U.S. 120, 133 (2000) (quoting Davis v. Mich. Dep’t of
Treasury, 489 U.S. 803, 809 (1989)), because an act should
“be interpreted as a symmetrical and coherent regulatory
scheme, one in which the operative words have a consistent
meaning throughout,” Gustafson v. Alloyd Co., 513 U.S. 561,
569 (1995).

    Here, context matters. Section 9 prohibits the taking of
“fish or wildlife” only:
12            CTR. FOR BIO. DIVERSITY V. BLM

        [W]ith respect to any endangered species of
        fish or wildlife listed pursuant to section 1533
        of this title it is unlawful for any person . . . to
        . . . take any such species within the United
        States or the territorial sea of the United
        States [or] take any such species upon the
        high seas.

16 U.S.C. § 1538(a)(1). Section 9(a)(2) contains separate
protections for plants, but does not use the term “take.” See
16 U.S.C. § 1538(a)(2). Section 9 thus demonstrates that
when Congress uses the word “take,” it means to describe an
adverse action against animals, not plants. And, as the district
court noted, unlike the section 9(a)(1) protections for “fish or
wildlife,” the section 9(a)(2) prohibitions relating to plants
require “deliberate or malicious conduct.” Incidental takings,
by definition, are not deliberate. Given that one cannot be
held liable for the taking of a plant, it is difficult to conceive
how an incidental take “safe harbor” would be necessary for
plants.

      The Center counters that the Endangered Species Act
defines “take” in a manner that does not exclude plants.
Under the definitions section of the Act, “[t]he term ‘take’
means to harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect, or to attempt to engage in any such
conduct.” 16 U.S.C. § 1532(19). According to the Center, the
definition “does not distinguish between animals and plants
. . . . It defines only the act, not the victim or the crime.” As
the district court noted, however, the take definition in the
statute was part of the original Act. Before the 1982
amendments adding the incidental take provisions of sections
7 and 10, section 9 contained the only provision in which the
term “take” was used, and there it was unquestionably limited
             CTR. FOR BIO. DIVERSITY V. BLM                 13

to animals—to “fish or wildlife.” In drafting the take
definition, Congress necessarily had exclusively “fish or
wildlife” in mind because those were the only categories of
species at the time protected from takings.

    Putting the history of the Act aside for a moment, the text
of the take definition supports the same conclusion. The
majority of the words on the list most naturally describe
actions that cannot be directed against plants. For example,
one does not pursue a tree; one does not typically shoot a
shrub. See 16 U.S.C. § 1532(19). Conversely, there are no
words in the definition that could be applied exclusively to
plants, such as “uproot.” See id. The principle of noscitur a
sociis here guides our reading: “That several items in a list
share an attribute counsels in favor of interpreting the other
items as possessing that attribute as well.” Beecham v. United
States, 511 U.S. 368, 371 (1994). Words such as “harm” or
“collect,” though ordinarily applicable to actions taken
against both animals and plants, are best construed in a
manner similar to those words that surround them—namely,
words describing conduct affecting animals.

    Our decision in Arizona Cattle Growers’ Association
lends further support to the proposition that “take” applies to
animals only. In that case, we held that the Fish and Wildlife
Service acted arbitrarily and capriciously when it issued an
Incidental Take Statement “where there either was no
evidence that the endangered species existed on the land or no
evidence that a take would occur if the permit were issued.”
Ariz. Cattle Growers’ Ass’n, 273 F.3d at 1233. In reaching
our conclusion, we reasoned that section 7’s incidental take
provision was in essence a “safe harbor” for section 9; if an
approved activity might incidentally result in a taking, those
engaging in the activity need not fear section 9 liability so
14              CTR. FOR BIO. DIVERSITY V. BLM

long as they comply with the terms of the Fish and Wildlife
Service’s Incidental Take Statement. Id. at 1239–40. Because
there can be no incidental taking if there is no threat of a
section 9 taking, there necessarily is only “one standard for
‘taking’ within both Section 7(b)(4) . . . and Section 9.” Id. at
1239. Consequently, we “reject[ed] the argument that ‘taking’
should be applied differently” between the two sections. Id.
at 1240.3

     The Center parries Arizona Cattle Growers’ Association
with Center for Biological Diversity v. Salazar. In Center for
Biological Diversity, when the Fish and Wildlife Service first
listed the polar bear as “threatened,” it issued a rule applying
most of section 9’s protections but excluded the section 9
“take” prohibitions. 695 F.3d at 910. We held that an
Incidental Take Statement was nevertheless required. Id. As
we explained:

         [E]xemption from Section 9 take liability ‘is
         not the sole purpose of the [Incidental Take
         Statement]. If the amount or extent of taking
         specified in the [Incidental Take Statement] is
         exceeded, reinitiation of formal consultation
         is required . . . . Thus, the [Incidental Take
         Statement] serves as a check on the agency’s


   3
     Section 10 of the Endangered Species Act (the other incidental take
provision) authorizes the Secretary to permit “any taking otherwise
prohibited by section 1538(a)(1)(B) [section 9] of this title if such taking
is incidental to, and not the purpose of, the carrying out of an otherwise
lawful activity.” 16 U.S.C. § 1539(a)(1). That the provision considers an
incidental taking to be a subset of the takings referred to in section 9
further supports the Fish and Wildlife Service’s contention that Incidental
Take Statements exist to protect “fish or wildlife,” 16 U.S.C. § 1538(a)(1),
not plants.
             CTR. FOR BIO. DIVERSITY V. BLM                15

       original decision that the incidental take of
       listed species resulting from the proposed
       action will not [jeopardize the continued
       existence of the species].’ [Nat. Res. Def.
       Council, Inc. v. Evans, 279 F. Supp. 2d 1129,
       1182 (N.D. Cal. 2003)]. Accordingly,
       exemption from Section 9 take prohibitions
       does not negate the separate requirement that
       the Service ‘will provide’ an [Incidental Take
       Statement] along with its [Biological
       Opinion]. 50 C.F.R. § 402.14(i)(1).

Id. at 911 (some alterations in original).

    As the district court recognized, one could perceive
tension between Arizona Cattle Growers’ Association and
Center for Biological Diversity. While Arizona Cattle
Growers’ Association makes clear that there cannot be a
section 7 incidental taking where there is no section 9 taking
prohibition, Center for Biological Diversity divorces section
7’s incidental taking statements from section 9 taking
prohibitions in holding that the section 7 provision serves a
purpose beyond merely removing liability for otherwise
prohibited takings. Fully reconciling the two cases,
fortunately, is not necessary to resolve the issue at hand.
Accepting Center for Biological Diversity’s holding that an
Incidental Take Statement can be required where taking is not
prohibited, the concept of “taking” nevertheless continues to
derive its meaning from section 9 and the Act’s definition of
“take.” To understand what it means to incidentally take a
species, one must understand what it means to take a species;
to understand what it means to take, one necessarily looks to
section 9. Because section 9 applies to animals only, it
16           CTR. FOR BIO. DIVERSITY V. BLM

follows that one can neither “take” nor “incidentally take” a
plant.

    It is no wonder then that district courts have assumed that
the incidental take provisions apply to animals only. See, e.g.,
Cal. Native Plant Soc’y v. Norton, No. 01CV1742 DMS
(JMA), 2004 WL 1118537, at *8 (S.D. Cal. Feb. 10, 2004)
(“In the absence of a prohibition on the ‘take’ of plant
species, Defendants are correct that ‘such take cannot occur,
and no incidental take statement is needed.’”); N. Cal. River
Watch v. Wilcox, 547 F. Supp. 2d 1071, 1075 (N.D. Cal.
2008), aff’d, 633 F.3d 766 (9th Cir. 2010) (“[S]ection
10—allowing a private party to apply for an incidental take
permit—applies only to fish and wildlife; there is no section
10 incidental take permit provision for endangered plants.”).

                               C

    Read in context, the text of the statute is clear: the
Endangered Species Act does not require Biological Opinions
to contain Incidental Take Statements for threatened plants.
We therefore need not consider separately the Fish and
Wildlife Service’s interpretation of the statute. See Chevron,
467 U.S. at 842–43. Nonetheless, our reading of the law is
consistent with the Service’s longstanding interpretation of
the incidental take provision not to require the issuance of
Incidental Take Statements for threatened plants. See
Interagency Cooperation—Endangered Species Act of 1973,
51 Fed. Reg. 19926-01, 19935 to 19936 (July 3, 1986)
(codified at 51 C.F.R. pt. 402) (defining an incidental taking
as a taking that results from activities that violate “the
prohibition against taking in section 9 of the Act”); U.S. Fish
and Wildlife Service and National Marine Fisheries Service,
Final ESA Section 7 Consultation Handbook 6–10 (1998)
             CTR. FOR BIO. DIVERSITY V. BLM                  17

(stating that an Incidental Take Statement is required as part
of formal consultation “except for plant species”).
Accordingly, we would have deferred to the agency’s
reasonable interpretation of the statute and reached the same
result had the application of Chevron deference been
necessary in this case.

                              III

    The Center next argues that BLM’s decision to open
additional land to off-road vehicle use violated the Clean Air
Act (“CAA”), the Federal Land Policy and Management Act
(“FLPMA”), the National Environmental Policy Act
(“NEPA”), and the Administrative Procedure Act (“APA”).
In reaching its decision, BLM relied on an air quality analysis
demonstrating that emissions resulting from visitors to the
Dunes would not be increased impermissibly by the openings.
We must reject each of the Center’s challenges unless we are
persuaded that BLM’s analysis was “arbitrary, capricious, an
abuse of discretion, or otherwise not in accordance with law.”
5 U.S.C. § 706(2)(A) (APA); see Sierra Club v. U.S. E.P.A.,
671 F.3d 955, 961 (9th Cir. 2012) (reviewing CAA challenge
under APA standard); Mont. Wilderness Ass’n v. Connell,
725 F.3d 988, 994 (9th Cir. 2013) (reviewing FLPMA
challenge under APA standard); Ocean Advocates v. U.S.
Army Corps of Eng’rs, 402 F.3d 846, 858 (9th Cir. 2005)
(reviewing NEPA challenge under APA standard). An
agency’s analysis is arbitrary and capricious if it has “relied
on factors which Congress has not intended it to consider,
entirely failed to consider an important aspect of the problem,
offered an explanation for its decision that runs counter to the
evidence before the agency, or is so implausible that it could
not be ascribed to a difference in view or the product of
agency expertise.” Ranchers Cattlemen Action Legal Fund
18           CTR. FOR BIO. DIVERSITY V. BLM

United Stockgrowers of America v. U.S. Dept. of Agric.,
499 F.3d 1108, 1115 (9th Cir. 2007) (quoting Motor Vehicle
Mfrs. Ass’n v. State Farm Mutual Auto. Ins. Co., 463 U.S. 29,
43 (1983)). “This standard of review is ‘highly deferential,
presuming the agency action to be valid and affirming the
agency action if a reasonable basis exists for its decision.’”
Id. (quoting Indep. Acceptance Co. v. California, 204 F.3d
1247, 1251 (9th Cir. 2000)).

    As with the Center’s first challenge, we begin with a
review of the statutory scheme governing BLM’s air quality
analysis.

                               A

                               1

    The CAA was enacted “to protect and enhance the quality
of the Nation’s air resources so as to promote the public
health and welfare and the productive capacity of its
population.” 42 U.S.C. § 7401(b)(1). The Act authorizes the
Environmental Protection Agency (“EPA”) to establish
“national ambient air quality standards” for certain designated
pollutants. Id. § 7407. These pollutants include ozone
precursors, such as volatile organic compounds and nitrogen
oxides, and particulate matter with a diameter greater than 10
microns (“PM-10”). See 40 C.F.R. § 52.21; see generally
40 C.F.R. pt. 50. Under the scheme, States are divided into
“air quality control regions.” Id. § 7407. The governor of
each State is responsible for designating an area—an entire
air quality control region or portion thereof—as
“nonattainment” if it fails to meet national ambient air quality
standards. Id. Nonattainment areas are further classified as
“Marginal,” “Moderate,” “Serious,” “Severe,” and
             CTR. FOR BIO. DIVERSITY V. BLM                  19

“Extreme,” based on the severity of pollution present. Id.
§ 7511. The agency must undertake a full “conformity
determination . . . for each criteria pollutant or precursor
where the total of direct and indirect emissions of the criteria
pollutant or precursor in a nonattainment or maintenance area
caused by a Federal action would equal or exceed” listed de
minimis quantities. 40 C.F.R. § 93.153(b).

    In similar fashion, FLPMA requires the Secretary of the
Interior, in developing and revising land use plans, to
“provide for compliance with applicable pollution control
laws, including State and Federal air, water, noise, or other
pollution standards or implementation plans.” 43 U.S.C.
§ 1712(c)(8).

    Finally, before undertaking a proposed action, NEPA
requires federal agencies to take a “hard look” to determine
the potential impact an agency action may have on the
environment; such a review requires a “full and fair
discussion of significant environmental impacts.” Western
Watersheds Project v. Abbey, 719 F.3d 1035, 1047 (9th Cir.
2013) (quoting 40 C.F.R. § 1502.1).

                               2

    The Imperial County Air Pollution Control District, which
contains the Dunes, is classified as a “moderate”
nonattainment area for ozone and a “serious” nonattainment
area for PM-10, largely as a result of high winds and
particulate matter drifting across the border from nearby
Mexicali, Mexico. Under such classifications, BLM would be
required to undertake a full conformity determination
pursuant to EPA regulation if execution of BLM’s 2013
RAMP would result in an increase of 100 tons per year for
20           CTR. FOR BIO. DIVERSITY V. BLM

ozone emissions or 70 tons per year for PM-10. See 40 C.F.R.
§ 93.153(b). BLM initially concluded in its Draft
Environmental Impact Statement that implementation of its
preferred plan would increase volatile organic compound
emissions by 352 tons per year (generated primarily by
vehicle exhaust) and PM-10 emissions by 36,768 tons per
year (generated primarily by dust kicked up from
vehicles)—both well over the de minimis thresholds that
require conformity analyses under 40 C.F.R. § 93.153(b).

    Following the issuance of its draft statement for public
comment, BLM revised its analysis by changing certain
underlying assumptions supporting the initial conclusion that
the planned expansion would result in emissions exceeding de
minimis quantities. Specifically, BLM changed its
assumptions regarding the expected increase in the number of
vehicles to the Dunes, the manner in which they would be
used, and the amount of dust they might generate. As a result,
the Final Environmental Impact Statement concluded that
pollution resulting from BLM’s planned openings would not
increase ozone emissions and would actually decrease PM-10
emissions.

                              B

    The Center first argues that the assumptions supporting
BLM’s ultimate conclusion that implementation of the 2013
RAMP would not increase ozone emissions were arbitrary
and capricious. Specifically, the Center takes issue with
BLM’s assumptions regarding the number of individuals who
will visit the Dunes and how an average visitor will spend his
time recreating.
              CTR. FOR BIO. DIVERSITY V. BLM                  21

                               1

    In its Final Environmental Impact Statement, BLM
assumed, for purposes of its emissions analysis, that its plan
to open additional areas of the Dunes to off-road vehicle use
would not lead to an overall increase in the number of
visitors: “[V]isitor use of the Planning Area will remain the
same as current levels for all alternatives, and there would be
no incremental change in GHG [greenhouse gas] emissions
from the baseline.” The Center argues that such an
assumption cannot possibly be correct—that opening
additional areas to off-road vehicle use will necessarily attract
an increased number of off-road vehicle enthusiasts.

     Yet in litigation surrounding BLM’s 2003 RAMP, the
Center challenged BLM’s contention that the closing of
certain areas would result in a decline in visitors. The district
court agreed with the Center, concluding that “there is no data
in the record linking the interim closures to any reduced OHV
[off-highway vehicle] visitation levels at the Dunes.” Ctr. for
Biological Diversity, 422 F. Supp. 2d at 1149. BLM argues
that no data has surfaced since the previous litigation
demonstrating that opening or closing such areas would
change the number of visitors to the Dunes.

    Facts and data in the record tend to support the assertion
that opening further acreage to off-road vehicle use would not
lead to an increased number of visitors. Much of the area
scheduled to be opened is quite remote—far from camping
and staging areas and lacking in amenities such as restrooms.
And fluctuations in the number of visitors appear to be tied
more closely to historical trends and economic conditions
than to acreage. For example, after previous closures
22           CTR. FOR BIO. DIVERSITY V. BLM

visitation to the planning area increased initially, before
decreasing during a subsequent economic downturn.

    BLM’s analysis, of course, is not immune from criticism.
Of particular note is the inconsistency between BLM’s
emissions analysis and its economic analysis, the latter of
which assumed that opening additional acreage would in fact
result in an increased number of visitors. Nevertheless, the
existence of such an inconsistency is insufficient proof that
the emissions analysis was arbitrary and capricious. Indeed,
BLM had the discretion to apply different models and
assumptions in different circumstances. See San Luis &
Delta-Mendota Water Auth. v. Jewell, 747 F.3d 581, 610 (9th
Cir. 2014) (“[W]e give the [Fish and Wildlife Service] great
deference in its choice of scientific tools . . . .”). And, of
course, the assumption supporting the economic analysis may
simply be wrong—that it differs from the one contained in the
emissions analysis does not compel the conclusion that the
emissions analysis was flawed.

    We are confident that the Center could demonstrate
persuasively numerous ways in which BLM’s emissions
analysis could be improved. Mere differences in opinion,
however, are not sufficient grounds for rejecting the analysis
of agency experts. See Ecology Ctr. v. Castaneda, 574 F.3d
652, 656 (9th Cir. 2009). Because BLM’s assumptions
regarding visitation were supported by substantial evidence,
they deserve deference. See Ursack, Inc. v. Sierra
Interagency Black Bear Grp., 639 F.3d 949, 958 n.4 (9th Cir.
2011).
             CTR. FOR BIO. DIVERSITY V. BLM                  23

                               2

    In addition to criticizing BLM’s estimate of the number
of expected visitors, the Center attacks BLM’s assumptions
contained in its Final Environmental Impact Statement
relating to how visitors spend their time at the Dunes.
Specifically, the Center argues that BLM underestimated the
number of hours per day an average rider uses his off-road
vehicle, the distance he rides, and the speed at which he
travels (the numbers for these variables were significantly
higher in BLM’s Draft Environmental Impact Statement). As
with BLM’s prediction of the number of visitors, such
assumptions are entitled to deference so long as they are
supported by “substantial evidence.” See San Luis & Delta-
Mendota Water Auth., 747 F.3d at 608.

    For purposes of our analysis, however, BLM’s revised
assumptions regarding vehicle use are irrelevant. A
conformity analysis must be prepared only if the emissions
caused by the federal action—here, BLM’s “preferred
alternative” in the 2013 RAMP—exceed listed de minimis
levels. See 40 C.F.R. 93.153(b). BLM applied the same
assumptions relating to vehicle use to its preferred alternative
as to the baseline conditions against which BLM compared its
plan. The Center does not argue that opening more acreage to
off-road vehicles would affect the manner in which the
average visitor would use his off-road vehicle; it contends
instead that BLM’s assumptions regarding vehicle use, which
apply equally to all proposed alternatives, are wrong.
However, as the district court observed, if BLM’s assumption
that the number of visitors would not increase is correct, the
number of hours per day an average rider uses his off-road
vehicle, the distance he rides, and the speed at which he
travels have absolutely no effect on the calculation of whether
24           CTR. FOR BIO. DIVERSITY V. BLM

opening additional acreage to off-road vehicles will increase
emissions. The same logic undercuts the Center’s argument
that BLM failed to account for other sources of emissions,
such as campfires and generators. Absent an increase in
visitation, overall pollution will not change.

                              C

    The Center additionally challenges the “fugitive
particulate emissions” (PM-10) portion of BLM’s air-quality
analysis—specifically BLM’s procedure for evaluating the
characteristics of the soil found throughout the Dunes. Unlike
the assumptions regarding vehicle usage, a change in soil
evaluation methods is relevant even if the number of visitors
remains constant because soil characteristics vary throughout
the Dunes. PM-10 emissions thus depend on which portions
of the Dunes are open for off-road vehicle use.

                              1

    Vehicles kick up dust. As a general rule, greater silt
content in soil results in greater PM-10 emissions from
vehicle traffic. Conversely, when soil contains a greater
concentration of sand, PM-10 emissions are reduced. In its
original analysis, contained in the Draft Environmental
Impact Statement, BLM relied upon “standard assumptions”
regarding silt content to determine the amount of airborne
PM-10 off-road vehicles operating in the Dunes might
produce. After publishing the draft statement, BLM revisited
its analysis and “determined the standard assumptions that
were used greatly overestimated emissions.” BLM was
instead persuaded that actual soil samples would provide a
better foundation for the analysis and so officials proceeded
to test soil throughout the Dunes: “Sites were visited and
             CTR. FOR BIO. DIVERSITY V. BLM                 25

approximately 800 gram samples were collected. These
samples were returned to the office where they were sieved
and weighed to determine the various fractions of silt and
sand in the sample.” The testing demonstrated that soils on
the Dunes were predominantly sand, with over 75 percent of
each sample not passing through a mesh screen. Silt content
proved to be low, constituting less than 0.5 percent. Such
findings, when incorporated into the analysis, yielded a PM-
10 figure below the de minimis threshold. Indeed, because
BLM’s proposed openings would shift off-road vehicle use to
areas of the Dunes with lower silt content, and would
incorporate proposed mitigation measures, the new analysis
predicted a decrease in PM-10 emissions from the baseline.

                              2

    Under the CAA, States (and by delegation, local
governments) may develop individualized regulatory
programs called “state implementation plans” that specify
emissions limitations, in addition to other measures designed
to satisfy national ambient air quality standards for each
pollutant. 42 U.S.C. § 7410. Federal agencies may not
“engage in, support in any way or provide financial assistance
for, license or permit, or approve, any activity which does not
conform to an implementation plan.” Id. § 7506(c)(1).

    The Center argues that the soil sample method employed
by BLM was impermissible because it failed to conform to
Imperial County’s Implementation Plan. Rule 800 of the
Implementation Plan, entitled “General Requirements for
Control of Fine Particulate Matter (PM-10),” prescribes a
method for analyzing soil characteristics. Rule 800, section
G.1.e specifically governs the determination of silt content
for “Unpaved Roads and Unpaved Vehicle/Equipment Traffic
26            CTR. FOR BIO. DIVERSITY V. BLM

Areas.” The Center avers that because BLM ignored such
rule, the results of its analysis are void. BLM counters that
the Center’s proposed method is used solely to determine
whether a road is considered a “stabilized unpaved road” and
was therefore inapplicable for BLM’s purposes, viz. to
estimate PM-10 emissions from off-road vehicle usage.

    Rule 800, section G.1.e directs agencies to employ
methods contained in appendix B, section C of the Rule to
determine the silt content for “Unpaved Roads and Unpaved
Vehicle/Equipment Traffic Areas.” The appendix explains
that the purpose of such methods is “to determine whether an
area has a Stabilized Surface.” Rule 800, app. B, § A. Indeed,
the procedure culminates in a finding as to whether a surface
is “stable”: “If the average silt loading is less than 0.33 oz/ft2,
the surface is STABLE.” Id. app. B, § C.10 (“Step 9:
Examine Results.”). As BLM argues, the aim of testing under
appendix B, section C, is to determine whether a surface is in
fact a “Stabilized Unpaved Road,” which Rule 800 defines as
“[a]ny Unpaved Road or unpaved vehicle/equipment traffic
area surface which meets the definition of Stabilized Surface
as determined by the test method.” Id. § C.38. Rule 800
makes use of the “stabilized unpaved road” standard in
section F.5.c, where it requires those overseeing lands on
which off-road vehicles are used to employ methods such as
watering, paving, or speed restrictions to ensure that a surface
does not cease being a “stabilized unpaved road”—that is, to
ensure that excessive dust is not generated.

    Simply put, a “stabilized unpaved road” under Rule 800
is a standard—a surface over which vehicles travel without
kicking up excessive amounts of dust; one determines
whether the standard is met by using the test prescribed by
appendix B, section C. Contrary to the Center’s assertion, the
             CTR. FOR BIO. DIVERSITY V. BLM                 27

test prescribed by appendix B is not a procedure for gauging
PM-10 emissions generally. BLM’s use of an alternative
method for estimating PM-10 emissions was therefore
permissible.

                              D

    Finally, the Center argues that BLM impermissibly
disregarded concerns raised by EPA and the Imperial County
Air Pollution Control District regarding potential impacts on
the environment. We reject this argument for three reasons.

    First, ultimate responsibility for ensuring compliance with
applicable laws lies with the agency undertaking the proposed
action—here, BLM. See 42 U.S.C. § 7506(c). Second, that
another agency might prefer a different approach is
insufficient to demonstrate that BLM acted unreasonably. See
Edwardsen v. U.S. Dep’t of Interior, 268 F.3d 781, 786 (9th
Cir. 2001). Third, the record indicates that BLM did indeed
consider and respond to criticisms and concerns raised by
other agencies, as well as those from the general public.
BLM’s handling of input from other agencies was therefore
neither unlawful nor arbitrary and capricious.

                              E

    In challenging an agency determination such as this, the
Center had a steep hill to climb as “[r]eview under the
arbitrary and capricious standard is narrow”—a court will not
substitute its judgment for that of the agency. Ecology Ctr.,
574 F.3d at 656 (internal quotation marks omitted). Here, the
record demonstrates that BLM “considered the relevant
factors and articulated a rational connection between the facts
found and the choices made.” Arrington v. Daniels, 516 F.3d
28          CTR. FOR BIO. DIVERSITY V. BLM

1106, 1112 (9th Cir. 2008) (quoting Ranchers Cattlemen
Action Legal Fund, 415 F.3d at 1093). Under the
circumstances, the Center has failed to demonstrate that
BLM’s emissions analysis was arbitrary and capricious under
this deferential standard.

                            IV

   For the foregoing reasons, the decision of the district
court is AFFIRMED.
