Nrdc v. Usdot ( 2014 )


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  •                  FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    NATURAL RESOURCES DEFENSE               No. 12-56467
    COUNCIL, INC., a non-profit
    corporation; EAST YARD                     D.C. No.
    COMMUNITIES FOR ENVIRONMENTAL           2:09-cv-08055-
    JUSTICE, a non-profit corporation;        JAK-MAN
    COALITION FOR A SAFE
    ENVIRONMENT, a non-profit
    corporation,                              OPINION
    Plaintiffs-Appellants,
    v.
    U.S. DEPARTMENT OF
    TRANSPORTATION; RAY LAHOOD, in
    his official capacity as Secretary of
    Transportation; STATE OF
    CALIFORNIA, DEPARTMENT OF
    TRANSPORTATION; VICTOR MENDEZ,
    Administrator, Federal Highway
    Administration; JEFFREY PANIATI, in
    his official capacity as Acting
    Deputy Director of the Federal
    Highway Administration,
    Defendants-Appellees,
    ALAMEDA CORRIDOR
    TRANSPORTATION AUTHORITY,
    Real Party in Interest-Appellee.
    2                        NRDC V. USDOT
    Appeal from the United States District Court
    for the Central District of California
    John A. Kronstadt, District Judge, Presiding
    Argued and Submitted
    May 14, 2014—Pasadena, California
    Filed October 30, 2014
    Before: John T. Noonan, Kim McLane Wardlaw,
    and Raymond C. Fisher, Circuit Judges.
    Opinion by Judge Wardlaw
    SUMMARY*
    Environmental Law
    The panel affirmed the district court’s summary judgment
    in favor of federal and state defendants in an action brought
    by environmental groups alleging that the defendants violated
    the Clean Air Act and the National Environmental Policy Act
    by failing to properly evaluate and disclose the potential
    environmental impact of a planned expressway connecting
    the Ports of Los Angeles and Long Beach to the I-405
    freeway.
    Pursuant to the Clean Air Act (CAA), the states must
    adopt a State Implementation Plan that provides for the
    *
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    NRDC V. USDOT                            3
    implementation and maintenance of national air quality
    standards. The CAA contains a “conformity” provision that
    prohibits federal participation in any project that fails to
    conform to an approved State Implementation Plan. The CAA
    delegated to the Environmental Protection Agency (EPA) and
    the U.S. Department of Transportation the duty to establish
    procedures to assure conformity for transportation projects.
    Pursuant to that authority, the EPA promulgated regulations
    mandating a “hot-spot analysis” for certain pollutants,
    including PM2.5 - the pollutant at issue. In the course of the
    expressway project’s approval process, the defendants
    conducted an air quality Conformity Determination, which
    involved a qualitative hot-spot analysis of existing
    concentration of PM2.5, and an Environmental Impact
    Statement (EIS) as required by the National Environmental
    Policy Act.
    The panel held that the defendants were not required to
    estimate PM2.5 increases within the area immediately adjacent
    to the proposed expressway, and concluded that the
    defendants’ Conformity Determination complied with the
    CAA. Specifically, the panel held that the CAA’s statutory
    phrase “any area” was ambiguous, and the governing
    regulations did not decisively answer whether the CAA
    required qualitative hot-spot analysis within the immediate
    vicinity of the project area during the time period at issue, but
    the EPA’s and Department of Transportation’s interpretation
    of the regulations¯permitting the type of analysis performed
    here by the defendants¯were entitled to considerable
    deference. The panel further held that the defendants’
    Conformity Determination was neither arbitrary nor
    capricious.
    4                   NRDC V. USDOT
    Finally, the panel held that the EIS prepared by the
    defendants took the requisite “hard look” at the freeway
    project’s likely consequences and probable alternatives, and
    therefore the EIS comported with the National Environmental
    Policy Act.
    COUNSEL
    Adriano Martinez (argued), David Pettit, Natural Resources
    Defense Council, Santa Monica, California; Robert E.
    Yuhnke, Robert Yuhnke & Associates, Boulder, Colorado,
    for Plaintiffs-Appellants.
    J. David Gunter II (argued), Ignacia S. Moreno, David
    Glazer, Norman Rave, United States Department of Justice,
    Washington, D.C., for Defendants-Appellees.
    Jocelyn Denise Thompson (argued), Sharon Rubalcava,
    Shiraz D. Tangri, Marisa Blackshire, Alston & Bird LLP, Los
    Angeles, California, for Real Party in Interest-Appellee.
    OPINION
    WARDLAW, Circuit Judge:
    Natural Resources Defense Council, East Yard
    Communities for Environmental Justice, and Coalition for a
    Safe Environment (collectively “NRDC”) appeal the district
    court’s grant of summary judgment in favor of the U.S.
    Department of Transportation and other federal and state
    defendants (collectively “Defendants”). NRDC argues that
    Defendants violated the federal Clean Air Act (“CAA”) and
    NRDC V. USDOT                                5
    the National Environmental Policy Act (“NEPA”) by failing
    to properly evaluate and disclose the potential environmental
    impact of a planned expressway connecting the Ports of Los
    Angeles and Long Beach to the I-405 freeway. We have
    jurisdiction under 28 U.S.C. § 1291, and we affirm the district
    court’s grant of summary judgment to Defendants.
    I.
    The Port of Los Angeles is our nation’s busiest container
    port.1 Considered together with the adjacent Port of Long
    Beach, this port complex is among the ten busiest in the
    world, and it accounts for roughly forty percent of all
    waterborne cargo that enters the United States. BILL
    SHARPSTEEN, THE DOCKS 53-54 (2011). The port’s cargo
    volume is projected to continue rising for decades.2
    Although the ports are an economic boon for the Los
    Angeles region, they also affect air quality in the surrounding
    area, especially in the adjacent communities of San Pedro and
    Wilmington. These impacts are projected to worsen with the
    rise in container volume at the ports. The State Route 47
    Expressway Project (“Project”) is one of several port-related
    infrastructure projects designed to ease traffic congestion and
    mitigate air pollution. If built, the Project will connect the
    ports to the I-405 freeway via an elevated, 1.7 mile-long
    1
    Strategic Plan 2012-2017, THE PORT OF LOS ANGELES, at 1 (2012),
    http://www.portoflosangeles.org/pdf/strategic_plan_2012_lowres.pdf (last
    visited Sept. 24, 2014).
    2
    See Port Master Plan, THE PORT OF LOS ANGELES, at 9 (Feb. 2014),
    http://www.portoflosangeles.org/planning/pmp/Amendment%2028.pdf
    (last visited Sept. 24, 2014).
    6                     NRDC V. USDOT
    expressway. The Project’s sponsors, which are now the
    Defendants in this litigation, assert that the Project will better
    integrate the ports with the freeway system, thereby reducing
    the need for surface-street travel by trucks carrying shipping
    containers, and the pollution generated while they run idle at
    traffic signals and railroad crossings.
    In the course of the Project’s approval process,
    Defendants conducted an air quality Conformity
    Determination and an Environmental Impact Statement
    (“EIS”). As one component of the Conformity Determination
    study, Defendants performed a qualitative “hot-spot” analysis
    that measured existing concentrations of PM2.5, a type of fine
    particulate matter, and estimated the Project’s likely impact
    on PM2.5 levels. Because there was no PM2.5 receptor located
    within the immediate vicinity of the Project, Defendants
    based their qualitative hot-spot analysis on data from a
    receptor five miles away from the project area. Defendants
    released a draft Conformity Determination in November
    2008. Following a round of comments and revisions, the
    final Conformity Determination was issued in May 2009.
    Meanwhile, Defendants prepared an EIS as required by
    NEPA. The EIS process began in 2004, and Defendants
    released a draft EIS in August 2007. The draft EIS prompted
    numerous comments, including comments from NRDC, to
    which Defendants responded at length. The comments also
    spurred Defendants to conduct additional studies, such as a
    Traffic Sensitivity Analysis and a Health Risk Assessment
    that detailed the Project’s likely health impacts, including an
    increased risk of cancer in the areas immediately adjacent to
    the Project. Defendants released the final version of the EIS
    in May 2009, and signed the Record of Decision in August
    2009.
    NRDC V. USDOT                           7
    In November 2009, NRDC filed a complaint in the
    Central District of California alleging that Defendants’
    approval of the Project violated CAA, NEPA, and the
    Administrative Procedure Act. At the district court’s request,
    the parties briefed and argued cross-motions for summary
    judgment. On June 29, 2012, the district court issued an
    order granting summary judgment in Defendants’ favor. This
    appeal follows.
    II.
    A district court’s decision on cross-motions for summary
    judgment is reviewed de novo. Am. Civil Liberties Union of
    Nev. v. City of Las Vegas, 
    466 F.3d 784
    , 790 (9th Cir. 2006).
    “We view the evidence in a light most favorable to the non-
    moving party and decide whether there are any genuine issues
    of material fact and whether the district court correctly
    applied the substantive law.” FTC v. Stefanchik, 
    559 F.3d 924
    , 927 (9th Cir. 2009).
    Under the Administrative Procedure Act, we must “hold
    unlawful and set aside agency action, findings, and
    conclusions found to be . . . arbitrary, capricious, an abuse of
    discretion, or otherwise not in accordance with law.”
    5 U.S.C. § 706(2)(A). “Review under the arbitrary and
    capricious standard is narrow, and we do not substitute our
    judgment for that of the agency.” Barnes v. U.S. Dep’t of
    Transp., 
    655 F.3d 1124
    , 1132 (9th Cir. 2011).
    “When Congress has ‘explicitly left a gap for an agency
    to fill, there is an express delegation of authority to the
    agency to elucidate a specific provision of the statute by
    regulation,’ and any ensuing regulation is binding in the
    courts unless procedurally defective, arbitrary or capricious
    8                    NRDC V. USDOT
    in substance, or manifestly contrary to the statute.” United
    States v. Mead Corp., 
    533 U.S. 218
    , 227 (2000) (quoting
    Chevron, U.S.A., Inc. v. Natural Res. Def. Council, Inc.,
    
    467 U.S. 837
    , 843-44 (1984)). Even if the agency has not
    formally interpreted the statute, Chevron deference applies
    when it has “promulgated a rule based on an implicit
    interpretation of the statute.” Schleining v. Thomas, 
    642 F.3d 1242
    , 1246 (9th Cir. 2011). An agency’s interpretation of its
    own regulation is “controlling unless plainly erroneous or
    inconsistent with the regulation.” Auer v. Robbins, 
    519 U.S. 452
    , 461 (2000) (internal quotation marks omitted).
    III.
    A.
    The CAA mandates joint efforts between the federal
    government and the states to combat air pollution. Under the
    CAA’s statutory framework, the federal Environmental
    Protection Agency (“EPA”) begins by establishing National
    Ambient Air Quality Standards (“NAAQS”) for certain types
    of pollutants. 42 U.S.C. § 7409. Then, the EPA designates
    areas throughout the United States as “attainment,”
    “nonattainment,” or “maintenance” for each type of pollutant
    depending on whether these national standards have been
    met. See 40 C.F.R. § 93.101 (defining these terms). For
    PM2.5, the pollutant at issue here, the EPA has designated the
    South Coast Air Basin—which encompasses the ports as well
    as most of the greater Los Angeles area—as “nonattainment.”
    The details of NAAQS enforcement are left to the states, each
    of which must adopt a State Implementation Plan that
    provides for the implementation and maintenance of national
    air quality standards. 42 U.S.C. § 7410(a)(1).
    NRDC V. USDOT                          9
    The CAA also contains a “conformity” provision that
    prohibits federal participation in any project that fails to
    conform to an approved State Implementation Plan.
    42 U.S.C. § 7506(c)(1). The statute defines “conformity” to
    mean, in relevant part, that:
    such activities will not—
    (i) cause or contribute to any new violation of
    any standard in any area;
    (ii) increase the frequency or severity of any
    existing violation of any standard in any area;
    or
    (iii) delay timely attainment of any standard
    or any required interim emission reductions or
    other milestones in any area.
    
    Id. § 7506(c)(1)(B).
    The CAA does not define the term “any
    area.” Instead, it delegates to the EPA and the U.S.
    Department of Transportation (“DOT”) the duty to
    “promulgate, and periodically update, criteria and procedures
    for demonstrating and assuring conformity in the case of
    transportation plans, programs, and projects.”            
    Id. § 7506(c)(4)(B).
    Acting pursuant to that authority, the EPA has
    promulgated regulations that mandate a “hot-spot analysis”
    for several air pollutants, including PM2.5. Hot-spot analysis
    is described as
    an estimation of likely future localized . . .
    PM2.5 pollutant concentrations and a
    10                    NRDC V. USDOT
    comparison of those concentrations to the
    national ambient air quality standards. Hot-
    spot analysis assesses impacts on a scale
    smaller than the entire nonattainment or
    maintenance area . . . and uses an air quality
    dispersion model to determine the effects of
    emissions on air quality.
    40 C.F.R. § 93.101. Project sponsors must carry out this hot-
    spot analysis to ensure that the project does not “cause or
    contribute to any new localized . . . PM2.5 violations, increase
    the frequency or severity” of such violations, or “delay timely
    attainment” of air quality goals. 
    Id. § 93.116(a).
    When a
    project’s sponsors conduct a hot-spot analysis, concentrations
    “must be estimated and analyzed at appropriate receptor
    locations in the area substantially affected by the project.” 
    Id. § 93.123(c)(1).
    Hot-spot analyses may be either qualitative or
    quantitative. “Where quantitative analysis methods are not
    available,” as was true of PM2.5 during the period at issue
    here, the demonstration required by § 93.116(a) “must be
    based on a qualitative consideration of local factors.” 
    Id. § 93.123(b)(2).
    The parties agree that Defendants were
    required to conduct a qualitative hot-spot analysis rather than
    a quantitative analysis.
    In March 2006, the EPA and DOT jointly published the
    Transportation Conformity Guidance for Qualitative Hot-spot
    Analyses in PM2.5 and PM10 Nonattainment and Maintenance
    Areas (“Conformity Guidance”). According to the EPA, all
    qualitative PM2.5 analyses “should be completed” according
    to the Conformity Guidance. 71 Fed. Reg. 12468, 12471
    (Mar. 10, 2006). The Conformity Guidance does not define
    NRDC V. USDOT                          11
    “any area,” nor does it refer to “appropriate receptor
    locations.” It does, however, provide a detailed methodology
    for how project sponsors should conduct qualitative PM2.5
    hot-spot analyses, and it features several examples of
    permissible analyses.
    NRDC’s CAA claim turns on whether the statute’s use of
    the phrase “any area” means that Defendants were required
    to estimate PM2.5 increases within the area immediately
    adjacent to the proposed expressway. If Defendants were
    required to do so, then it follows that their approval of the
    Project was contrary to law and must be set aside. If not, then
    their Conformity Determination complied with the CAA.
    B.
    1.
    NRDC argues that the plain meaning of § 7506(c)(1)(B)
    compels the conclusion that “any area” means “‘all’ or
    ‘every’ part of the ‘area’ affected by project emissions,” and
    thus that Defendants were required to measure PM2.5
    concentrations within the immediate vicinity of the Project.
    We agree that “read naturally, the word ‘any’ has an
    expansive meaning.” Ali v. Fed. Bureau of Prisons, 
    552 U.S. 214
    , 219 (2008) (alterations and internal quotation marks
    omitted). However, NRDC’s plain meaning argument
    ignores a critical, obvious ambiguity in the phrase “any area”:
    the word “area.”
    On its own, the word “area” does not tell us whether
    Defendants were required to measure PM2.5 concentrations
    within the area immediately adjacent to the proposed
    expressway or in any other “area.” The plain meaning of
    12                   NRDC V. USDOT
    “area” encompasses a wide variety of sizes. “Area” is
    defined as “a region or part of a town, a country, or the
    world,” “a space allocated for a specific purpose,” or “the
    extent or measurement of a surface or piece of land.” NEW
    OXFORD AMERICAN DICTIONARY 83 (3rd ed. 2010).
    Additionally, the statutory context does not allow us to
    pinpoint the meaning of “area.” A different provision of the
    CAA requires that states send the EPA “a list of all areas (or
    portions thereof) in the State,” 42 U.S.C. § 7407(d)(1)(A), but
    this usage of “area” appears to refer to entire air quality
    regions, which often include multiple counties. Likewise, the
    statutory section concerning State Implementation Plans
    repeatedly uses the term “areas” to describe air quality
    regions. E.g., 
    id. § 7410(a)(2)(I).
    Thus, we are convinced
    that the statutory phrase “any area” is ambiguous.
    2.
    Because Congress has not “directly spoken to the precise
    question at issue,” 
    Chevron, 467 U.S. at 842
    , we look to the
    relevant agencies’ interpretations of the ambiguous phrase
    “any area” during the period at issue in this appeal. NRDC
    asserts that the EPA has adopted a regulatory interpretation
    that supports its understanding of “any area,” and it argues
    that EPA and DOT interpretations to the contrary are not
    entitled to judicial deference.
    NRDC’s argument begins with an EPA rule interpreting
    the key statutory phrase “increase the frequency or severity
    of any existing violation of any standard in any area.” 42
    U.S.C. § 7506(c)(1)(B)(ii). According to the EPA’s
    regulatory definition,
    NRDC V. USDOT                                  13
    [i]ncrease the frequency or severity means to
    cause a location or region to exceed a
    standard more often or to cause a violation at
    a greater concentration than previously
    existed . . . .
    40 C.F.R. § 93.101 (emphasis added). NRDC argues the term
    “a location” refers to an area smaller than the project area,
    such as the area immediately adjacent to the expressway. In
    March 2010, nearly a year after the Defendants issued their
    Conformity Determination, the EPA issued an amended rule
    which “specifically clarifies that the term ‘any area’ in CAA
    section 176(c)(1)(B) applies to any portion of a nonattainment
    or maintenance area, including the local area affected by a
    transportation project.”3 75 Fed. Reg. 14,260, 14,276 (Mar.
    24, 2010). NRDC argues that the EPA’s 2010 amendment to
    40 C.F.R. § 93.116 confirms that the term “a location”
    referred to an area smaller than the project area.
    NRDC also points to the regulatory requirement that hot-
    spot analyses estimate pollutant concentrations at
    “appropriate receptor locations in the area substantially
    affected by the project.” 40 C.F.R. § 93.123(c)(1). In
    NRDC’s view, this provision’s use of the plural “locations,”
    and its reference to “the area significantly affected by the
    project,” impliedly interprets the CAA’s “any area”
    requirement to mandate collection and analysis of data drawn
    3
    In explaining its amended rule, the EPA noted that “[i]n practice,
    EPA’s regulations will ensure that any project that creates a new violation
    or worsens an existing violation of the NAAQS in the local area affected
    by the project (either by increasing the number of violations or the severity
    of an existing violation) will not be found to conform.” 75 Fed. Reg.
    14,260, 14,278 (Mar. 24, 2010).
    14                   NRDC V. USDOT
    from the project’s immediate vicinity. Finally, NRDC cites
    the EPA’s 1997 response to a public comment on proposed
    hot-spot rules. In this response, the EPA noted that some
    commenters had proposed that “a project should be allowed
    to make a violation worse in a place not frequented by the
    public if it improves air quality and eliminates violations
    where public exposure is more likely.” 62 Fed. Reg. 43,780,
    43,798 (Aug. 15, 1997). The EPA, however, rejected this
    view, explaining that
    Clean Air Act section 176(c)(1)(B) states that
    transportation projects must not cause or
    contribute to any new violation of any
    standard in any area, or increase the frequency
    or severity of any existing violation of any
    standard in any area. It is not public exposure
    to a violation of a standard that the Clean Air
    Act language prohibits; it prohibits any
    violation of any standard in any area. The
    conformity rule cannot override the Clean Air
    Act to make exceptions that create new or
    worsen existing violations.
    
    Id. NRDC’s arguments,
    while not without merit, fail to
    persuade us that during the period at issue in this appeal the
    EPA interpreted “any area” in the manner NRDC proposes.
    First, that 40 C.F.R. § 93.101 refers to “a location or region”
    does not persuade us that the “area” referenced is the area
    immediately adjacent to the expressway as opposed to the
    broader project area. Although the EPA clarified the term
    “any area” in its 2010 amendments to mean “any portion of
    a nonattainment or maintenance area, including the local area
    NRDC V. USDOT                         15
    affected by the transportation project,” the EPA did not
    clearly indicate that this interpretation should apply
    retroactively. 75 Fed. Reg. at 14,276; cf. Kankamalage v.
    INS, 
    335 F.3d 858
    , 862 (9th Cir. 2003) (observing that a
    regulation may not apply retroactively unless it
    “unambiguously directs retroactive application”).
    Nor do we find the language of 40 C.F.R. § 93.123(c)(1)
    particularly relevant. To begin with, it is not clear from the
    language or structure of this provision whether its
    “appropriate receptor locations” requirement applies to all
    hot-spot analyses or only the more rigorous quantitative
    analyses. Section 93.123(c)(1) is listed as one of several
    “General requirements,” but § 93.123(b)(2) explicitly carves
    out an exception for qualitative analyses, which “must be
    based on a qualitative consideration of local factors.” The
    EPA’s own statements and publications also indicate that the
    “appropriate receptor locations” provision is inapplicable to
    qualitative hot-spot analyses. The qualitative Conformity
    Guidance says nothing about “receptors” or “appropriate
    receptor locations.” In a 2010 response to public comments,
    the EPA noted that it “intends to describe appropriate
    receptor locations in its forthcoming quantitative PM hot-spot
    guidance.” 75 Fed. Reg. 14,260, 14,282 (Mar. 24, 2010)
    (emphasis added). The EPA’s recent quantitative Conformity
    Guidance made good on this promise.                 See EPA,
    Transportation Conformity Guidance for Quantitative Hot-
    spot Analyses 113-15 (Nov. 2013) (defining and explaining
    appropriate receptor locations).
    Finally, the EPA’s 1997 response does not settle the
    matter. The response does not discuss hot-spot analysis,
    much less the proper application of qualitative PM2.5 hot-spot
    analysis. In addition, the response simply reiterates “that
    16                    NRDC V. USDOT
    transportation projects must not cause or contribute to any
    new violation of any standard in any area, or increase the
    frequency or severity of any existing violation of any
    standard in any area.” 62 Fed. Reg. at 43,798. It does not
    interpret the term “any area” or state that the term refers to an
    area immediately adjacent to a transportation project. Thus,
    the 1997 response does not establish the meaning of the term
    “any area” at the time the Defendants issued their Conformity
    Determination.
    Therefore, the governing regulations do not decisively
    answer whether the CAA required qualitative hot-spot
    analysis within the immediate vicinity of the project area
    during the time period at issue.
    3.
    The EPA and DOT’s Conformity Guidance implicitly, but
    authoritatively, fills this void by interpreting these ambiguous
    regulations to permit the type of analysis Defendants
    performed here. Although the Conformity Guidance does not
    explicitly interpret terms such as “any area,” “a location,” or
    “appropriate receptor locations,” the methodological
    examples it sets forth make clear that a qualitative PM2.5 hot-
    spot analysis may be performed by analyzing data from an
    existing air quality monitor in a location similar to the project
    area, even if that monitor is not located within the immediate
    vicinity of the new project. Because this interpretation is not
    “plainly erroneous or inconsistent with the regulation,” 
    Auer, 519 U.S. at 461
    , we must afford it considerable deference.
    The Conformity Guidance, which the two agencies jointly
    published in March 2006, was “developed . . . to help state
    and local agencies meet the [regulatory] hot-spot analysis
    NRDC V. USDOT                          17
    requirements.” Conformity Guidance at 2. Indeed, it states
    that “future qualitative PM2.5 . . . hot-spot analyses should be
    based on today’s new guidance.” Id.; see also 71 Fed. Reg.
    at 12471 (referring to the Conformity Guidance and stating
    that “[q]ualitative PM2.5 hot-spot analyses should be
    completed according to joint EPA and DOT guidance”). The
    Conformity Guidance “highlights two methods for
    completing qualitative PM2.5 . . . analyses,” including one in
    which the project sponsor compares the project location to
    “another location with similar characteristics.” Conformity
    Guidance at 17. The comparison method “involves
    reviewing existing highway or transit facilities that were
    constructed in the past and built in locations similar to the
    proposed project and, whenever possible, near an air quality
    monitor (a ‘surrogate’) to allow a comparison of PM2.5 . . . air
    quality concentrations.” 
    Id. The Conformity
    Guidance then provides several examples
    of permissible comparisons. Two of these examples suggest
    that a project can conform even if it increases PM2.5
    concentrations in the area immediately surrounding the
    project, and even if the surrogate is in violation of NAAQS.
    In Example A, a project sponsor plans to build a bus terminal
    that will “significantly increase diesel bus traffic at the
    project’s location.” 
    Id. at 27.
    The project sponsor measures
    PM2.5 emissions in “the vicinity” of a similar, already-existing
    bus terminal. 
    Id. The project
    sponsor also uses a “nearby”
    air monitor to determine existing air-quality conditions. 
    Id. The “similar”
    bus terminal’s PM2.5 emissions violate NAAQS
    standards. 
    Id. However, because
    the new bus terminal will
    include “mitigation measures,” the project sponsor concludes
    that the new terminal will conform. 
    Id. In Example
    B, the
    project sponsor plans to modify a highway interchange
    “connecting a primary route to an interstate” which will be
    18                   NRDC V. USDOT
    used by a “significant number of diesel vehicles.” 
    Id. at 28.
    The project sponsor collects air quality information from the
    project’s “location.” 
    Id. The project
    is found to meet the
    conformity hot-spot requirements because “any increase in
    the emissions due to traffic changes associated with the
    project[] would be offset by decreases in the emissions from
    the transportation facility.” 
    Id. Only one
    published decision has addressed the
    Conformity Guidance, but it is well-reasoned and highly
    instructive. In Audubon Naturalist Society of the Central
    Atlantic States, Inc. v. U.S. Department of Transportation,
    
    524 F. Supp. 2d 642
    (D. Md. 2007), environmental advocacy
    groups challenged the PM2.5 hot-spot analysis for a highway
    project, in part because the project sponsor used an existing
    air monitor located outside the immediate vicinity of the
    proposed highway. 
    Id. at 701.
    The district court held that the
    regulations governing qualitative PM2.5 hot-spot analyses are
    ambiguous and that the Conformity Guidance is entitled to
    Auer deference as a reasonable interpretation of those
    regulations. 
    Id. at 697–99.
    The court then noted that the
    Conformity Guidance explicitly recommends the “monitor
    comparison method,” in which data from “another location
    with similar characteristics” is used to project the likely
    impact of the new project. 
    Id. at 700.
    Ultimately, the court
    upheld the project sponsors’ analysis, reasoning that the
    Conformity Guidance neither mentions a distance
    requirement nor requires installation of new air monitors;
    rather, it only requires project sponsors to use nearby air
    monitors at “locations similar to the proposed project.” 
    Id. at 701
    (quoting Conformity Guidance at 17).
    We also note that the Federal Highway Administration
    (“FHWA”), an agency within the DOT, has published several
    NRDC V. USDOT                              19
    examples of permissible qualitative PM2.5 hot-spot analyses.
    According to FHWA’s website, these are analyses that “could
    be replicated in other areas of the country.”4 Two of these
    examples—the Woodrow Wilson Bridge and Prairie Parkway
    projects—are of particular interest. In the Woodrow Wilson
    Bridge hot-spot analysis, the project sponsor based its
    estimated PM2.5 concentrations on a surrogate air monitor
    twenty miles away from the project site.5 Because the
    estimated traffic levels for the Woodrow Wilson Bridge
    project were similar to the traffic levels at the surrogate
    monitor, and because the surrogate did not violate PM2.5
    standards, the sponsor concluded that the project would not
    violate PM2.5 standards. 
    Id. at 21.
    Similarly, in the Prairie
    Parkway hot-spot analysis, the project sponsor based its
    estimated PM2.5 concentrations on a surrogate air monitor
    roughly ten miles away from the project site.6 Traffic levels
    near the surrogate were similar to estimated traffic levels for
    the project, and the surrogate did not violate PM2.5 standards.
    
    Id. at 23.
    Thus, the sponsor concluded that Prairie Parkway
    project would not violate PM2.5 standards. 
    Id. While we
    acknowledge that these examples are less authoritative than
    the Conformity Guidance—in part because the studies
    4
    FHWA, Examples of Transportation Conformity Practices,
    http://www.fhwa.dot.gov/environment/air_quality/conformity/practices/
    (last visited Sept. 24, 2014).
    5
    Woodrow Wilson Bridge PM2.5 Conformity Analysis, at 15 (Oct. 2006),
    http://www.fhwa.dot.gov/environment/air_quality/conformity/practices/
    woodrow_wilson.pdf (last visited Sept. 24, 2014).
    6
    Fine Particulate Matter (PM2.5) Project Level Hot-Spot Analysis:
    Prairie Parkway Study, ILL. DEP’T OF TRANSP. 9 (Jan. 4, 2008),
    http://www.fhwa.dot.gov/environment/air_quality/conformity/practices/
    prairie_parkway.pdf (last visited Sept. 24, 2014).
    20                   NRDC V. USDOT
    themselves were conducted by state agencies—FHWA’s
    endorsement provides further indication that Defendants were
    permitted to rely on a surrogate air monitor outside the
    immediate vicinity of the project. See United States v. Mead
    Corp., 
    533 U.S. 218
    , 234 (2001) (“[A]n agency’s
    interpretation may merit some deference whatever its form.”);
    J.G. v. Douglas Cnty. Sch. Dist., 
    552 F.3d 786
    , 797 n.8 (9th
    Cir. 2008) (“Although a state agency’s interpretation of
    federal law is not entitled to deference, the Secretary’s
    approval of that agency’s interpretation is due some deference
    because it shows a federal agency’s interpretation of the
    federal statute that it is charged to administer.” (citation
    omitted)).
    NRDC offers no persuasive reason why we should not
    rely upon these agency interpretations. Having already
    concluded that the language of the CAA and the hot-spot
    regulations are ambiguous, we address NRDC’s three
    remaining arguments: that the CAA delegates interpretive
    authority to the EPA, not FHWA; that the agencies’
    interpretations were not adopted through notice-and-comment
    rulemaking; and that FHWA’s application of the Conformity
    Guidance represents an inconsistent and unexplained change
    in policy. NRDC’s first remaining objection makes little
    sense. The EPA and DOT, to whom Congress expressly
    delegated interpretive authority, jointly published the
    Conformity Guidance on which Defendants relied. 42 U.S.C.
    §§ 7506(c)(4)(B); EPA, Transportation Conformity Guidance
    for Quantitative Hot-spot Analyses 1 (Nov. 2013). Moreover,
    FHWA—which performed the hot-spot analysis here and
    published examples of permissible qualitative analyses on its
    website—is an agency within the DOT that reports to the
    Secretary of Transportation.
    NRDC V. USDOT                              21
    NRDC’s second objection fares no better. We afford
    Auer deference to an agency’s interpretation of its own
    regulations regardless of whether that interpretation was
    adopted through notice-and-comment rulemaking. See, e.g.,
    Chase Bank USA, N.A. v. McCoy, 
    131 S. Ct. 871
    , 881 (2011)
    (deferring to agency’s interpretation of its own regulation that
    was advanced in an amicus brief).7
    NRDC’s third remaining argument, its objection to the
    agency’s purported change in policy, is more properly
    analyzed as a challenge to this particular Conformity
    Determination, not as a challenge to the agency’s general
    interpretation of the permissible methodology for conducting
    qualitative hot-spot analyses. We therefore turn to the review
    of the Conformity Determination before us.
    C.
    Having concluded that the agencies’ interpretation of the
    appropriate hot-spot analysis governs, it is clear that
    Defendants’ Conformity Determination was neither arbitrary
    nor capricious.
    Defendants performed a qualitative PM2.5 hot-spot
    analysis using the comparison method described in the
    Conformity Guidance. Defendants chose the North Long
    Beach air monitoring station, located roughly five miles away
    from the far end of the project, as a surrogate because its
    PM2.5 concentrations were “representative of the project
    7
    NRDC’s reliance on High Sierra Hikers Ass’n v. Blackwell, 
    390 F.3d 630
    (9th Cir. 2004), is misplaced. High Sierra Hikers stands for the
    uncontroversial—but inapposite—proposition that an informal agency
    interpretation is not entitled to Chevron deference. 
    Id. at 648.
    22                       NRDC V. USDOT
    area.” To reach this determination, Defendants compared the
    North Long Beach station to a second monitoring station
    located closer to the project area.8 They found that annual
    average daily traffic, trucks as a percentage of all traffic, and
    PM2.5 concentrations at the closer station were all similar to
    those at the North Long Beach station, and therefore
    concluded that “the North Long Beach station reflects the
    same traffic conditions as at the project location, and the
    monitoring data are shown to be representative of ambient air
    quality for the project area.”
    Defendants then used the North Long Beach PM2.5 data as
    a baseline to estimate the Project’s likely impacts on PM2.5
    concentrations. Defendants projected that although the
    Project might increase total vehicle miles traveled in
    comparison to the no-build alternative, this impact would be
    offset by faster vehicle speeds and reduced traffic congestion.
    As a result, Defendants concluded, “PM2.5 emissions of the
    build alternatives would be the same or less than the No Build
    alternative,” and “[b]ased on the current ambient PM2.5
    concentrations in the project area, the project is not expected
    to have [a] significant localized PM2.5 concentration increase
    when compared to the No Build alternative.” Thus, because
    the Project would not cause a new PM2.5 violation, increase
    the severity of an existing violation, or delay the
    implementation of national air quality standards for PM2.5,
    Defendants concluded that the Project conforms to statutory
    and regulatory requirements.
    Defendants’ Conformity Determination using this
    comparison method was a reasonable application of the EPA
    8
    This closer station was not chosen for the hot-spot analysis because it
    was relatively new and thus lacked extensive historical data.
    NRDC V. USDOT                          23
    and DOT’s Conformity Guidance.             The Conformity
    Determination compares favorably to the hot-spot analysis
    approved in Audubon, as well as to the Woodrow Wilson
    Bridge and Prairie Parkway analyses endorsed by the FWHA.
    The Conformity Guidance makes clear that Defendants were
    permitted to use a surrogate air monitor, and this monitor’s
    distance from the Project—about one mile from the near end
    of the Project, and five miles from the far end—was well
    within the ranges approved in Audubon and the Woodrow
    Wilson and Prairie Parkway examples. In addition,
    Defendants used a second air monitor to verify that the North
    Long Beach station was representative of air quality in the
    project area, further bolstering the accuracy of their
    qualitative analysis.
    IV.
    Under NEPA, federal agencies must prepare an EIS when
    considering “major Federal actions significantly affecting the
    quality of the human environment.” 42 U.S.C. § 4332(C).
    Federal regulations require that the EIS “provide full and fair
    discussion of significant environmental impacts,” 40 C.F.R.
    § 1502.1, as well as “state how alternatives considered in it
    and decisions based on it will or will not achieve the
    requirements of [NEPA] and other environmental laws and
    policies,” 
    id. § 1502.2(d).
    The EIS’s discussion of
    alternatives “should present the environmental impacts of the
    proposal and the alternatives in comparative form, thus
    sharply defining the issues and providing a clear basis for
    choice among options by the decisionmaker and the public.”
    
    Id. § 1502.14.
    Generally, our review is limited to whether the EIS
    contains “a reasonably thorough discussion of the significant
    24                   NRDC V. USDOT
    aspects of the probable environmental consequences.” City
    of Carmel-by-the-Sea v. U.S. Dep’t of Transp., 
    123 F.3d 1142
    , 1150 (9th Cir. 1997) (internal quotation marks
    omitted). “Once satisfied that a proposing agency has taken
    a ‘hard look’ at a decision’s environmental consequences, our
    review is at an end.” 
    Id. at 1151
    (alterations and internal
    quotation marks omitted). NRDC contends that Defendants
    violated NEPA because their EIS failed to address whether
    the potential increase in PM2.5 concentrations would violate
    2006 NAAQS standards and failed to fully disclose the
    Project’s likely effects on public health.
    Contrary to NRDC’s argument, the EIS did not
    impermissibly rely on outdated air quality standards. In
    2006, the EPA updated the NAAQS standard for PM2.5,
    cutting the maximum permissible level to 35 micrograms per
    cubic meter. 71 Fed. Reg. at 61,144 (Oct. 17, 2006). These
    new standards did not go into effect for transportation
    conformity purposes until December 2010, over a year after
    the Conformity Determination was completed. See 75 Fed.
    Reg. 14260, 14262 (Mar. 24, 2010) (“Transportation
    conformity for the 2006 PM2.5 NAAQS does not apply until
    December 14, 2010.”).
    Further, Defendants correctly contend that the EIS was
    forthright in discussing the new standard. For example, the
    EIS acknowledged that even though PM2.5 levels were below
    the old NAAQS standard in the two preceding years, “the
    current federal 24-hour PM2.5 standard of 35 [micrograms per
    cubic meter] was exceeded each year in the past 3 years.”
    The EIS also discussed at length the results of Defendants’ air
    quality study, and concluded that any localized increase in
    PM2.5 would be offset by reduced vehicle congestion and
    idling in the project area as a whole. The EIS also
    NRDC V. USDOT                           25
    incorporated Defendants’ response to NRDC’s comment on
    this point. Defendants noted that according to the results of
    the air quality study, “the project will not adversely affect the
    human environment by contributing to increased PM2.5
    concentrations in the study area or delay attainment of the
    NAAQS regardless of whether the study area is subject to the
    existing or revised 24-hour NAAQS.”
    In addition, Defendants’ EIS adequately disclosed the
    Project’s likely health effects. The EIS included a Health
    Risk Assessment that was subject to the public comment and
    review process. In the Health Risk Assessment, Defendants
    disclosed that the Project would lead to increased PM10 and
    PM2.5 concentrations in the immediate vicinity of the Project,
    and how those increased concentrations could have adverse
    health effects for local residents. The Health Risk
    Assessment also acknowledged that this type of
    transportation project usually leads to increased PM2.5
    concentrations in the area immediately adjacent to the project.
    Defendants also conducted detailed studies based on
    2006-2007 meteorological data, where they estimated cancer-
    and other health-risk increases at thousands of residences,
    schools, parks, and other areas in the immediate vicinity of
    the Project. Defendants explained the study results with
    color-coded diagrams illustrating the precise locations where
    adverse health effects would be the greatest. They also
    included statistical discussions and tables illustrating that
    roughly 97% of the adverse health affects would be due to
    diesel particulate matter concentrations. Additionally,
    Defendants determined that a heating, ventilation, and air
    conditioning retrofit program for residences within the
    vicinity of the significant impact zone would be a feasible
    mitigation measure.
    26                  NRDC V. USDOT
    Because we are satisfied that Defendants took a “hard
    look” at the Project’s likely consequences and probable
    alternatives, see 
    Carmel-by-the-Sea, 123 F.3d at 1151
    , we
    agree with the district court that the EIS comported with
    NEPA requirements.
    V.
    Defendants’ Conformity Determination did not violate the
    CAA, nor did their EIS violate NEPA. Accordingly, we
    AFFIRM the district court’s grant of summary judgment.