Sierra Club v. Van Antwerp , 661 F.3d 1147 ( 2012 )


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  •  United States Court of Appeals
    FOR THE DISTRICT OF COLUMBIA CIRCUIT
    Argued September 22, 2011       Decided November 29, 2011
    Amended January 30, 2012
    No. 10–5284
    SIERRA CLUB, ET AL.,
    APPELLEES
    v.
    ROBERT L. VAN ANTWERP, LIEUTENANT GENERAL, U.S.
    ARMY CORP OF ENGINEERS, ET AL.,
    APPELLEES
    SIERRA PROPERTIES I, LLC, ET AL.,
    APPELLANTS
    Consolidated with 10–5297, 10–5345
    Appeals from the United States District Court
    for the District of Columbia
    (No. 1:07–cv–01756)
    Lane N. McFadden, Attorney, U.S. Department of
    Justice, argued the cause for federal appellants. With him on
    the briefs was Lisa E. Jones, Attorney. Jessica O'Donnell,
    2
    Attorney, and R. Craig Lawrence, Assistant U.S. Attorney,
    entered appearances.
    Douglas M. Halsey, T. Neal McAliley, and Angela D.
    Daker were on the briefs for appellants Sierra Properties I,
    LLC, et al.
    Eric R. Glitzenstein argued the cause for appellees Sierra
    Club, et al. With him on the briefs was Howard M. Crystal.
    Before: GARLAND and KAVANAUGH, Circuit Judges, and
    WILLIAMS, Senior Circuit Judge.
    Opinion for the Court filed by Senior Circuit Judge
    WILLIAMS.
    WILLIAMS, Senior Circuit Judge: In 2007 the U.S. Army
    Corps of Engineers issued a permit authorizing the discharge
    of dredge and fill material into specified wetlands outside
    Tampa, Florida; it thereby enabled construction of a large
    mall. A number of firms are involved on the permittee’s side
    in these appeals, but we will simplify by referring to them all,
    as well as the project, as “CCTC,” standing for “Cypress
    Creek Town Center.”             Three environmental groups
    (collectively referred to as the “Sierra Club”) brought suit in
    district court to challenge issuance of the permit. (The suit
    names the heads of the Department of the Interior and the U.S.
    Fish and Wildlife Service as well, but we treat the Corps as a
    stand-in for all federal defendants.) Plaintiffs invoked three
    statutes: the National Environmental Policy Act (“NEPA”),
    the Clean Water Act (“CWA”), and the Endangered Species
    Act (“ESA”). After some complications described below, the
    district court issued a decision finding that the Corps had not
    fully complied with its obligations under NEPA and the
    CWA, but rejecting the plaintiffs’ ESA claim. It granted
    summary judgment for the Sierra Club on the first two claims
    3
    and for the Corps on the third. Sierra Club v. Van Antwerp,
    
    719 F. Supp. 2d 58
    (D.D.C. 2010).
    CCTC and the Corps appealed, and the Sierra Club cross-
    appealed. We affirm in part, reverse in part, and remand,
    concluding that the Corps did satisfy the demands of the three
    relevant statutes, except for failing to respond, in its treatment
    of the NEPA and ESA requirements, to a material contention
    as to the project’s impact on an endangered species, the
    eastern indigo snake.
    * * *
    Because CCTC proposed to discharge dredge and fill
    material into wetlands classified as “waters of the United
    States,” it was required to secure a permit from the Corps
    under § 404 of the CWA, 33 U.S.C. § 1311(a), 1362(7). The
    Corps originally issued the permit in 2007, allowing CCTC to
    discharge such material into about 54 acres of wetlands. In
    exchange, the Corps required various conservation measures,
    including the preservation, creation, or enhancement of
    wetlands on about 13 acres of the project site and nearly 120
    acres offsite. The Sierra Club filed suit in October 2007, but
    soon thereafter the Corps observed two unauthorized
    discharges of “sediments and turbid water” from the project
    site into nearby Cypress Creek, and accordingly suspended the
    permit. The district court granted the Corps’s request to
    remand the case to it for a reevaluation of the permit. After
    issuing a new public notice, the Corps determined that the
    discharges were the product of “human error” rather than a
    flaw with the project itself. It reinstated the permit in
    September 2009, but required additional “corrective
    measures.” The Sierra Club filed a revised complaint
    challenging the new permit. The district court granted split
    summary judgments as noted above.
    4
    As we review grants of summary judgment de novo, we
    are on this appeal in reality reviewing the decision of the
    Corps, not that of the district court. Natural Resources
    Defense Council v. Daley, 
    209 F.3d 747
    , 752 (D.C. Cir.
    2000). Our review is governed by the usual standards of 5
    U.S.C. § 706(2)(A) and Motor Vehicle Mfrs. Ass’n v. State
    Farm, 
    463 U.S. 29
    (1983).
    * * *
    CWA. The governing regulations bar the Corps from
    granting a CWA fill permit when “[t]here is a practicable
    alternative to the proposed discharge that would have less
    adverse effect on the aquatic ecosystem.”              40 C.F.R.
    § 230.12(a)(3)(i). They specify that “[a]n alternative is
    practicable if it is available and capable of being done after
    taking into consideration cost, existing technology, and
    logistics in light of overall project purposes.” 40 C.F.R.
    § 230.10(a)(2). If (as here) a project’s purpose does not
    require proximity to water, “practicable alternatives that do
    not involve special aquatic sites [such as wetlands, see 
    id. § 230.41]
    are presumed to be available.” 
    Id. § 230.10(a)(3).
    The Sierra Club contended (and contends here) that in fact
    there were practicable alternatives—other sites, or alternative
    ways of using the CCTC site—having less adverse effect.
    The Corps rejected these claims.              Resolution of the
    practicability issue turns on four subissues: (1) use of the
    site’s fair market value as its cost, rather than CCTC’s (lower)
    out-of-pocket cost; (2) failure on the Corps’s part to update
    the fair market value in its second look at the permit (which
    took place after the onset of the global financial meltdown in
    2008); (3) the Corps’s use of 8% as the minimum rate of
    return necessary for an alternative to be considered
    practicable; and (4) CCTC’s intention to provide more
    5
    parking per 1000 square feet of retail space than is provided
    on average, locally and indeed nationally.
    For any given minimum rate of return, assumption of a
    lower cost for the site (see J.A. 613-36, 1660) will tend to
    render “practicable” less intensive uses, i.e., uses inflicting
    less ecological damage. This fact drives the Sierra Club’s
    argument for acquisition cost, which in this case happened to
    be lower than fair market value. But the Sierra Club’s
    contention that the regulation required the Corps to use the
    developer’s acquisition cost is ill-founded.
    First, as a matter of simple language, opportunity cost
    (the value the owner could realize by a current sale) is a well-
    recognized form of cost. This is obviously true in economics,
    and the practicability test, though certainly neither a cost-
    benefit test nor an efficiency test, nonetheless encompasses
    economic factors. And courts have recognized opportunity
    cost as a variant of “cost.” Thus, the Supreme Court, in
    upholding the Federal Communications Commission’s
    decision to set certain rates “on a forward-looking basis
    untied to [the providers’] investment,” cited opportunity cost
    by way of analogy. Verizon v. FCC, 
    535 U.S. 467
    , 475, 499
    n.17 (2002); see also Natural Gas Clearinghouse v. FERC,
    
    108 F.3d 397
    , 400 (D.C. Cir. 1997). Second, the regulations’
    evaluation of alternatives requires consideration of cost on
    both sides of the comparison, and the cost of an alternative
    project site would presumably be that site’s market value.
    The comparison would be meaningful only if the Corps used
    the same metric for all options.             Third, 40 C.F.R.
    § 230.10(a)(2), in directing consideration of “cost,” can
    sensibly (perhaps most sensibly, but we need not so decide)
    mean the cost of proceeding with the project as planned; for
    this, clearly, the relevant measure of the developer’s land cost
    is what it foregoes by proceeding (rather than selling the land
    and realizing its market value). See Corps’s Combined Reply
    6
    and Response Br. 6-7. Fourth, whereas use of opportunity
    cost minimizes subjective, applicant-specific factors, reliance
    on the developer’s acquisition cost would create the odd
    possibility that an alternative practicable for one applicant
    would be impracticable for another. Finally (and this is really
    a variation of the fourth point), to use out-of-pocket cost
    would create an anomaly: An applicant with a low acquisition
    cost could resell the site at market value and thereby enable a
    successor developer to refute practicability claims that had
    been fatal for the seller. Accordingly, we have no difficulty
    whatever deferring to the Corps’s reasonable choice to use the
    land’s market value, rather than the developer’s acquisition
    cost.
    Peripheral to the acquisition-cost claim is the Sierra
    Club’s attack on the Corps’s failure to update the land’s
    market value when it reinstated the permit in 2009, after land
    values had fallen sharply, especially in the so-called “sand”
    states, including Florida. The Sierra Club notes that the Corps
    did update some plans and data, mostly related to the
    mitigation plan and stormwater management, and it thus
    claims an arbitrary inconsistency on the Corps’s part. But the
    Corps’s decision to update ecological but not economic data
    appears reasonable in light of the Corps’s reasons for
    reexamining the original permit. As its December 2008
    public notice explained, it suspended that permit because of
    unauthorized discharges of turbid water, and then undertook
    to decide whether to reinstate, modify, or revoke the permit,
    saying that its decision would “be based on an evaluation of
    the reassurances given to the Corps about the likelihood of
    future discharges of turbid water from the CCTC project site
    into Cypress Creek and wetlands on the site.” J.A. 1546-47.
    Though the Corps also stated that it would “evaluate any other
    facts and issues as necessary,” J.A. 1546, we see no basis in
    this for requiring it to restart its entire permitting analysis
    from zero. Given the scope of the 2009 permit re-analysis, it
    7
    was reasonable for the Corps to update only the plans and data
    related to ecological matters.
    The Sierra Club also attacks the Corps’s acceptance of
    the applicant’s contentions that an 8% rate of return was
    necessary to secure financing and that the planned project
    configuration was the only way to achieve that return. The
    Sierra Club claims that the record does not support use of an
    8% rate; assumption of a lower required rate of return, of
    course, would tend to increase the range of practicable
    alternatives.
    The CCTC submitted several reports, including one
    prepared by Ernst & Young, that examined the rates of return
    expected from comparable projects in the Tampa area. These
    reports produced estimates ranging from 7.6% to 10.06%.
    The Ernst & Young report concluded that a 7.6% return would
    be a “reasonable rate to expect” for the project when
    completed, but the project was subject to “a number of
    development risk factors” since it had not yet been completed.
    Joint Appendix (“J.A.”) 1465. The report stressed the need
    for a “spread” between the rate of return on a project still
    under development and the rate of return on a “stabilized
    operating property.” J.A. 1465. In addition, the record
    contained data indicating that Tampa regional malls had a
    “going-in capitalization rate” of 7.7%, with that term defined
    as “the first year NOI [net operating income] (before capital
    items of tenant improvements and leasing commissions and
    debt service but after real estate taxes) divided by present
    value (or purchase price).” J.A. 835. That of course suggests
    that it would be necessary to apply some non-trivial increment
    to the 7.6% or 7.7% estimates to make them suitable for
    calculating the minimum acceptable return on an as-yet
    unbuilt mall. We think the record plainly supports the Corps’s
    use of an interest rate at the low end of the range that was in
    8
    evidence, and with its modest excess over the very lowest
    figures plainly justifiable.
    The last of the practicability issues relates to the project’s
    planned number of parking spaces—a serious matter because
    parking accounts for such a large share of the mall’s surface.
    The Sierra Club argues that “CCTC would have more parking
    than any existing comparable mall in the Tampa area.” Sierra
    Club Opening Br. 53. The record does not make it clear
    exactly how many parking spaces CCTC is expected to have,
    but gives a range of 5.13 to 6.59 parking spaces per 1,000
    square feet of retail space, and the Sierra Club estimates the
    overall ratio as being 5.4. J.A. 572; Sierra Club Opening Br.
    55. CCTC submitted various items of evidence on the point:
    On one hand it provided developer guidelines from Target,
    Costco, and Kohls that required 5, 5.5, and 6 spaces,
    respectively, per 1,000 square feet of retail space, and on the
    other, it also submitted letters from other Florida developers
    stating that retail tenants “typically” have “4.5 to 5” parking
    spaces per 1,000 square feet of retail space. J.A. 601, 604.
    In fact both sides agree that CCTC’s parking ratio
    exceeds that of nearby malls. But CCTC defends its above-
    average ratio by pointing to the above-average proportion of
    restaurants in its project. While the Sierra Club does not
    contest the restaurant-parking link, it argues that there is no
    reason for so many restaurants. CCTC, in turn, seeks to
    justify the high proportion by saying that it aims to create
    more than a traditional mall. Whereas traditional malls use
    4.8% of their square footage for restaurants, “lifestyle centers”
    use 11.3%; CCTC, a self-described “town center,” is between
    these two figures at 8.08%. Agency Record (“A.R.”) 4605-
    06, 4663.
    Given the nature of Sierra Club's arguments to the agency
    on this point, the Corps's acceptance of CCTC's parking ratio
    9
    was not arbitrary or capricious in light of the practicability
    regulations.    Those require the Corps to evaluate the
    practicability of alternatives “in light of overall project
    purposes.” 40 C.F.R. § 230.10(a)(2). The regulations provide
    that “it will generally be assumed that appropriate economic
    evaluations have been completed, the proposal is
    economically viable, and is needed in the market place,” 33
    C.F.R. § 320.4(q), but they reserve to the agency an override
    power, saying that “the district engineer in appropriate cases,
    may make an independent review of the need for the project
    from the perspective of the overall public interest.” 
    Id. There appears
    to be little judicial interpretation of the process, but it
    has yielded one constraint that seems logically necessary:
    “[A]n applicant cannot define a project in order to preclude
    the existence of any alternative sites.” Sylvester v. U.S. Army
    Corps of Engineers, 
    882 F.2d 407
    , 409 (9th Cir. 1989). There
    is nothing suggesting that CCTC's project definition falls
    below that benchmark, and the Sierra Club has not articulated
    any other, more binding constraint.
    The Sierra Club observed in a letter to the Corps that
    even if “town center” malls feature more restaurants than
    traditional malls, that fact “does not clearly demonstrate that
    reduced parking is impracticable.” We do not think this
    observation was enough to impose on the Corps the task of
    evaluating the practicability of non-“town center” alternatives.
    As it was, the Corps studied eleven alternative locations for
    the project and considered four alternative on-site
    configurations. J.A. 466-69, 1080-82. While the case does
    not require us to say the minimum burden a challenger must
    meet to trigger an additional study (and the concomitant
    examination of the project's “purpose”), the Sierra Club's
    remark was not enough. It did not even argue that this purely
    commercial project could achieve the 8% return required to
    obtain financing by shifting from a town center to a traditional
    mall. Accordingly, the Corps was not arbitrary (or in
    10
    violation of the CWA) in accepting CCTC's conception of the
    mall's design, including its relatively high proportion of
    restaurant space, and hence in finding that fewer parking
    spaces did not represent a practicable, less environmentally
    damaging, means to satisfy that purpose.
    NEPA. NEPA requires that federal agencies prepare
    Environmental Impact Statements (“EISs”) for “major Federal
    actions significantly affecting the quality of the human
    environment.” 42 U.S.C. § 4332(C). “If any significant
    environmental impacts might result from the proposed agency
    action then an EIS must be prepared before the [agency]
    action is taken.” Sierra Club v. Peterson, 
    717 F.2d 1409
    ,
    1415 (D.C. Cir. 1983) (emphasis omitted). An agency can
    avoid preparing an EIS if it issues a proper Finding of No
    Significant Impact (“FONSI”). In reviewing a FONSI our
    task is to determine whether the agency
    (1) has accurately identified the relevant environmental
    concern, (2) has taken a hard look at the problem in
    preparing its [FONSI or Environmental Assessment], (3)
    is able to make a convincing case for its finding of no
    significant impact, and (4) has shown that even if there is
    an impact of true significance, an EIS is unnecessary
    because changes or safeguards in the project sufficiently
    reduce the impact to a minimum.
    TOMAC v. Norton, 
    433 F.3d 852
    , 861 (D.C. Cir. 2006); see
    also 40 C.F.R. § 1501.4. Although our decisions have
    frequently (but not invariably—see, e.g., Public Citizen v.
    Nat’l Highway Traffic Safety Admin., 
    848 F.2d 256
    , 267 (D.C.
    Cir. 1988)) repeated the phrase “convincing case” since its
    original appearance in Maryland-National Capital Park and
    Planning Commission v. U.S. Postal Service, 
    487 F.2d 1029
    ,
    1040 (D.C. Cir. 1973), our scope of review is in fact the usual
    one. TOMAC itself made this clear, introducing the four
    11
    numbered criteria with the standard language of judicial
    review of administrative action: “arbitrary, capricious, or an
    abuse of 
    discretion.” 433 F.3d at 861
    .
    A regulation of the Council on Environmental Quality
    further explains: “Significantly as used in NEPA requires
    considerations of both context and intensity.” 40 C.F.R.
    § 1508.27. It then proceeds to list ten factors that “should be
    considered in evaluating intensity.” Although the district
    court focused on four of these factors and found they
    established that the project’s environmental impact would be
    “significant,” Sierra 
    Club, 719 F. Supp. 2d at 66-67
    , the Sierra
    Club on appeal makes arguments only with respect to three.
    We first address the factors mentioned in subsections (b)(3)
    and (b)(10), finding the Corps’s consideration adequate. As to
    subsection (b)(9), which relates to effects on endangered or
    threatened species, the Sierra Club’s arguments here overlap
    with those it makes in the ESA context, and we defer
    discussion to our treatment of those claims.
    Subsection (b)(3) refers to “[u]nique characteristics of the
    geographic area such as proximity to . . . wetlands.” 40
    C.F.R. § 1508.27(b)(3). Of course it was the project’s impact
    on wetlands that required a permit from the Corps in the first
    place. But the Corps found that “[t]he wetlands are of
    moderate quality as they were logged and some of them were
    ditched” and that “[t]he wetlands are predominantly forested
    (cypress) and not unique or rare in the landscape.” J.A. 1106.
    The district court observed that the Corps itself had found that
    wetlands provide “‘valuable storage areas for storm and flood
    waters,’” Sierra 
    Club, 719 F. Supp. 2d at 66
    (quoting J.A.
    1107), but that does not in itself compel a finding that these
    particular wetlands are “unique” within the meaning of
    subsection (b)(3).
    12
    Moreover, apart from the wetlands’ lack of uniqueness,
    the ultimate CCTC plan called for creation and preservation of
    substantial substitute wetlands, the sort of mitigation measures
    that we have found “sufficiently reduce the impact to a
    minimum.” Michigan Gambling Opposition v. Kempthorne,
    
    525 F.3d 23
    , 29 (D.C. Cir. 2008) (quoting 
    TOMAC, 433 F.3d at 861
    ), and that the Corps so found here. J.A. 1687. The
    Sierra Club argues that the Corps cannot rely on such
    mitigation, citing studies purporting to show that wetlands
    mitigation often fails, in large part because of the Corps’s lax
    enforcement. But even assuming that general attacks on the
    Corps’s monitoring of wetlands mitigation could ever justify
    its or our disregard of specific mitigation measures, here in
    fact the Corps verified that the measures were proceeding.
    J.A. 1494-1501, 1543, 1576, 1581-84. Moreover, its 2009
    permit added special conditions in response to early setbacks.
    J.A. 1695.
    Subsection (b)(10) directs attention to whether “the action
    threatens a violation of Federal, State, or local law or
    requirements imposed for the protection of the environment,”
    and the Sierra Club argues that the unauthorized 2008
    discharge of turbid water into Cypress Creek not merely
    threatened violations of those requirements but constituted
    such violations. The Corps found that this discharge was the
    result of “human error” and not a problem of design. J.A.
    1672. The district court ruled that “NEPA regulations make
    no exception for human error” and that an EIS should have
    been prepared because the “2008 discharge did, in fact
    violat[e] Federal, State and local environmental law.” Sierra
    
    Club, 719 F. Supp. 2d at 67
    . But the subsection’s reference to
    “threats” indicates that it is forward-looking. Given that the
    Corps required additional assurances from CCTC before
    reinstating the permit, J.A. 1682, 1696, it could reasonably
    find that a past violation did not “threaten” future violations.
    13
    ESA (and leftover NEPA issues). The Sierra Club also
    argues that the district court erred by upholding the Corps’s
    determination that formal consultation under the ESA was not
    required. The ESA requires that federal agencies “insure that
    any action authorized, funded, or carried out by such agency .
    . . is not likely to jeopardize the continued existence of any
    endangered species or threatened species or result in the
    destruction or adverse modification of habitat.” 16 U.S.C.
    § 1536(a)(2).      Regulations promulgated under the ESA
    provide that “[e]ach Federal agency shall review its actions at
    the earliest possible time to determine whether any action may
    affect listed species or critical habitat. If such a determination
    is made, formal consultation [with the Fish and Wildlife
    Service] is required.” 50 C.F.R. § 402.14(a). The regulations
    create an exception to that obligation where, as a result of
    informal consultation, the “Federal agency determines with
    the written concurrence of the Director [of the Fish and
    Wildlife Service], that the proposed action is not likely to
    adversely affect any listed species or critical habitat.” 
    Id. at §
    402.14(b). After issuing its first public notice in October
    2005, the Corps engaged in informal consultation with the
    Fish and Wildlife Service (“FWS”). A.R. 3093; J.A. 536,
    889. The FWS “concur[red] with the [Corps’s] determination
    that the proposed project [was] not likely to adversely affect
    the wood stork nor any other species listed under the ESA.”
    J.A. 893. Accordingly, the Corps did not undertake formal
    consultation; as a technical matter, it is the Corps’s dispensing
    with formal consultation to which the Sierra Club objects.
    The Sierra Club argues that the Corps’s determination
    was erroneous because the project may have adverse effects
    on habitat used by both the indigo snake and wood stork. In
    parallel with its ESA contention, the Sierra Club raises a
    NEPA argument, pointing to 40 C.F.R. § 1508.27(b)(9), under
    which an adverse effect on “an endangered or threatened
    species or its habitat” is an indication of “intensity” and thus
    14
    tends to militate in favor of finding “significance” and of
    requiring an EIS. In both ESA and NEPA contexts, we reject
    the Sierra Club’s wood stork claim but find that the Corps
    failed to adequately address indications of an adverse effect
    on the indigo snake.
    Of the two statutes, the ESA and NEPA, the ESA is
    (unsurprisingly) the more demanding on this point. Subject to
    the exception noted above, it requires the agency to engage in
    a formal consultation if it determines that the action in
    question “may affect listed species or critical habitat.” 50
    C.F.R. § 402.14(a) (emphasis added). NEPA triggers the EIS
    requirement only for “major Federal actions significantly
    affecting the quality of the human environment.” 42 U.S.C.
    § 4332(C) (emphasis added). The four-part test for review of
    a FONSI that we quoted at the outset of the NEPA discussion
    explains that a project with a potentially significant impact
    will not require an EIS if “changes or safeguards . . .
    sufficiently reduce the impact.” TOMAC v. 
    Norton, 433 F.3d at 861
    . We see no reason why the general principle of taking
    mitigation into account should not apply to the decision
    whether the ESA requires formal consultation. Cf. City of
    Sausalito v. O’Neill, 
    386 F.3d 1186
    , 1216-17, 1218-20 (9th
    Cir. 2004) (approving a biological assessment that relied on
    mitigation for its no-adverse effect finding).
    As to the wood stork, the Corps’s conclusions rested on
    the project’s mitigation measures, which will bring about a net
    gain of wood stork foraging habitat. During informal
    consultation, the FWS determined that 16.22 acres of
    “potential wood stork habitat” existed on the site pre-
    construction and that with mitigation 21.35 acres would exist
    post-construction, resulting in a net gain. J.A. 1118. But the
    Sierra Club argues that the government did not “address near
    term adverse impacts on breeding colonies while off-site
    mitigation is being implemented.” Sierra Club Opening Br.
    15
    81-82 (emphasis in original). The Corps’s answer here was to
    rely on the mitigation plan’s “more than a one-to-one
    replacement ratio to compensate for the temporal lag between
    the loss of a wetland’s foraging value and when the new
    resource achieves that value.” J.A. 905. We certainly cannot
    say that as a general matter a roughly 33% net quantitative
    gain in habitat offsets a non-trivial “temporal lag”; in an
    extreme case no members of the species would make it
    through to enjoy the replacement area. But here the FWS
    found that the lost habitat, although “within the core foraging
    areas [i.e., within 13 miles] of five wood stork breeding
    colonies,” was not within the “primary or secondary zone” of
    any colonies. J.A. 890. Given the relatively marginal role of
    the lost habitat, it does not seem arbitrary or in contravention
    of its statutory mandate for the Corps to find that the
    mitigation’s more than “one-to-one replacement ratio” made
    up for the temporary deprivation.
    For the indigo snake, the Corps’s 2007 mitigation plan
    concluded that “[i]nadequate habitat for maintenance of
    eastern indigo snakes exists on the impact site in its
    predevelopment state.” J.A. 997 (emphasis added). But
    conservation guidelines submitted in CCTC’s own application
    noted that the snake is “especially vulnerable” to habitat
    “fragmentation” because of the snake’s large range. J.A. 164.
    Nevertheless, the Corps and FWS did not address the
    fragmentation risk. After the permit was suspended in 2008,
    the Corps’s new public notice said that it would “reinitiate
    informal consultation with the [FWS] regarding the issues
    addressed in this public notice.” J.A. 1547.
    In this renewed proceeding, the Sierra Club submitted
    two declarations related to the eastern indigo snake. The first
    declarant, a local Sierra Club member, wrote that he had seen
    an eastern indigo snake on the project site in May 2007. J.A.
    1295. The second declaration was from Dr. Kenneth Dodd, a
    16
    herpetologist who as Staff Herpetologist for the Office of
    Endangered Species in the FWS had been “primarily
    responsible for the listing of the” eastern indigo snake as
    threatened under the ESA. Dr. Dodd asserted that the project
    site was an important “wildlife corridor” linking protected
    areas to the north and south. J.A. 1317. He noted that
    “movements over large areas of fragmented habitats expose
    Eastern Indigo Snakes to increased road mortality,” and that
    “the more edge there is in relation to protected habitat [i.e.,
    ratio of perimeter to surface area], the less likely large snakes
    can be maintained.” J.A. 1306. He claimed more broadly that
    the Corps had failed to consider how the project would
    adversely affect the snake through “fragmentation” of its
    “habitat in lands near the site as a result of impacts to the site
    and the wildlife corridor connecting these lands.” J.A. 1317.
    In its second FONSI, issued in August 2009, the Corps
    again did not address the impacts of habitat fragmentation.
    J.A. 1696-97. Given Dr. Dodd’s expertise and experience,
    and the seeming logic of his analysis, as well as CCTC’s own
    acknowledgment of the snake’s vulnerability to fragmentation
    risk, we think his comment qualifies as the sort of “relevant
    and significant” public comment to which an agency must
    respond, lest its action be arbitrary and capricious. See Cape
    Cod Hospital v. Sebelius, 
    630 F.3d 203
    , 211 (D.C. Cir. 2011).
    Accordingly, we must remand for further explanation by the
    Corps of its determination that the project was “not likely to
    adversely affect” the indigo snake. We do not reach the issue
    of whether formal consultation is required, but the Corps must
    make some determination on the issue of habitat
    fragmentation, both for ESA and NEPA purposes.
    17
    * * *
    Our decision here of course substantially alters the
    substantive merits outcome that underlay the district court’s
    injunction. Accordingly it will be suitable on remand for the
    court to entertain contentions relating to modification of that
    injunction.
    In short, we reverse the district court entirely as to the
    CWA; reverse it as to NEPA except insofar as the court
    required further explanation by the Corps as to potential
    fragmentation of the indigo snake’s habitat; and affirm its
    decision as to the ESA except in so far as it found the Corps’s
    analysis of the indigo snake issue adequate.
    The judgment of the district court is therefore
    Affirmed in part, reversed in part, and remanded.