Audubon Soc'y of Greater Denver v. U.S. Army Corps of Eng'rs ( 2018 )


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  •                                                                             FILED
    United States Court of Appeals
    PUBLISH                            Tenth Circuit
    UNITED STATES COURT OF APPEALS                November 5, 2018
    Elisabeth A. Shumaker
    FOR THE TENTH CIRCUIT                       Clerk of Court
    _________________________________
    AUDUBON SOCIETY OF GREATER
    DENVER,
    Petitioner - Appellant,
    v.                                                        No. 18-1004
    UNITED STATES ARMY CORPS OF
    ENGINEERS,
    Respondent - Appellee,
    and
    CASTLE PINES METROPOLITAN
    DISTRICT; CASTLE PINES NORTH
    METROPOLITAN DISTRICT;
    CENTENNIAL WATER AND
    SANITATION DISTRICT; CENTER OF
    COLORADO WATER CONSERVANCY
    DISTRICT; CENTRAL COLORADO
    WATER CONSERVANCY DISTRICT;
    TOWN OF CASTLE ROCK;
    COLORADO DEPARTMENT OF
    NATURAL RESOURCES,
    Intervenors Respondents - Appellees.
    _________________________________
    Appeal from the United States District Court
    for the District of Colorado
    (D.C. No. 1:14-CV-02749-PAB)
    _________________________________
    Kevin Lynch, Environmental Law Clinic, University of Denver, Sturm College of Law,
    Denver, Colorado, appearing for Appellant.
    Sommer H. Engels, Attorney, Environment and Natural Resources Division, United
    States Department of Justice, Washington, DC (Jeffrey H. Wood, Acting Assistant
    Attorney General, United States Department of Justice, Washington, DC; Eric Grant,
    Deputy Assistant Attorney General, United States Department of Justice, Washington,
    DC; Jennifer Scheller Neumann, Michael Gray, Phillip R. Dupre, Dustin J. Maghamfar,
    Attorneys, Environment and Natural Resources Division, United States Department of
    Justice, Washington, DC; Catherine E. Grow, Of Counsel, Office of Counsel, United
    States Army Corps of Engineers, Omaha District, Omaha, Nebraska; Daniel Inkelas, Of
    Counsel, Office of the Chief Counsel, United States Army Corps of Engineers, with her
    on the brief), appearing for Appellee United States Army Corps of Engineers.
    Cynthia H. Coffman, Attorney General, Denver, Colorado, and Scott Steinbrecher,
    Assistant Solicitor General, Denver, Colorado, on the brief for Appellee Colorado
    Department of Natural Resources.
    Bennett W. Raley, Deborah L. Freeman, William Davis Wert, and Trout Raley, Denver,
    Colorado, on the brief for Appellees Castle Pines Metropolitan District, Castle Pines
    North Metropolitan District, Centennial Water and Sanitation District, Center of
    Colorado Water Conservancy District, Central Colorado Water Conservancy District, and
    Town Of Castle Rock.
    _________________________________
    Before BRISCOE, LUCERO, and MATHESON, Circuit Judges.
    _________________________________
    BRISCOE, Circuit Judge.
    _________________________________
    This is an Administrative Procedure Act challenge to the Army Corps of
    Engineers’ approval of a project to store more water in the Chatfield Reservoir in
    Colorado. Petitioner Audubon Society of Greater Denver sought review of the Corps’
    decision, arguing that the Corps’ review and approval of the project failed to comply with
    the National Environmental Policy Act, 42 U.S.C. §§ 4321–4370m-12, and the Clean
    Water Act, 33 U.S.C. §§ 1251–1388. The district court denied the petition for review
    after concluding that the Corps’ decision was not arbitrary or capricious. Audubon also
    2
    moved to supplement the administrative record. The district court denied the motion
    because it found that the administrative record sufficiently informed the Corps’ analysis.
    Exercising jurisdiction pursuant to 28 U.S.C. § 1291, we AFFIRM.
    I
    A.     Statutory Background
    In this case, we must decide whether the Corps complied with NEPA and the
    CWA when it approved the Chatfield Storage Reallocation Project, which will allow
    certain water providers in the Denver metropolitan area to store 20,600 acre-feet of water
    in the Chatfield Reservoir. “In NEPA, Congress codified rules designed to focus both
    agency and public attention on the environmental effects of proposed actions and thereby
    facilitate informed decisionmaking by agencies and allow the political process to check
    those decisions.” WildEarth Guardians v. U.S. Fish & Wildlife Serv., 
    784 F.3d 677
    , 690
    (10th Cir. 2015) (quotation marks and alteration omitted). “NEPA itself does not
    mandate particular results, but simply prescribes the necessary process.” Robertson v.
    Methow Valley Citizens Council, 
    490 U.S. 332
    , 350 (1989).
    NEPA requires the Corps to “include” an Environmental Impact Statement “in
    every recommendation or report on proposals for . . . major Federal actions significantly
    affecting the quality of the human environment.” 42 U.S.C. § 4332(C). An EIS
    “provide[s] full and fair discussion of significant environmental impacts and . . .
    inform[s] decisionmakers and the public of the reasonable alternatives which would
    avoid or minimize adverse impacts or enhance the quality of the human environment.”
    3
    40 C.F.R. § 1502.1. At issue in this appeal is whether the Corps adequately addressed
    and discussed the identified reasonable alternatives.
    The discussion of alternatives “is the heart of the” EIS. 
    Id. § 1502.14.
    “[I]t 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. The Corps
    was required to:
    (a) Rigorously explore and objectively evaluate all reasonable
    alternatives, and for alternatives which were eliminated from
    detailed study, briefly discuss the reasons for their having been
    eliminated.
    (b) Devote substantial treatment to each alternative considered in
    detail including the proposed action so that reviewers may evaluate
    their comparative merits.
    (c) Include reasonable alternatives not within the jurisdiction of the
    lead agency.
    (d) Include the alternative of no action.
    (e) Identify the agency’s preferred alternative or alternatives, if one
    or more exists, in the draft statement and identify such alternative in
    the final statement unless another law prohibits the expression of
    such a preference.
    (f) Include appropriate mitigation measures not already included in
    the proposed action or alternatives.
    
    Id. As long
    as “the adverse environmental effects of the proposed action are adequately
    identified and evaluated, the agency is not constrained by NEPA from deciding that other
    values outweigh the environmental costs.” 
    Robertson, 490 U.S. at 350
    . “Other statutes
    may impose substantive environmental obligations on federal agencies, but NEPA merely
    4
    prohibits uninformed—rather than unwise—agency action.” 
    Id. at 351
    (footnote
    omitted).
    Unlike NEPA, which focuses on process, the CWA imposes substantive
    requirements on the Corps. Hillsdale Envtl. Loss Prevention, Inc. v. U.S. Army Corps of
    Eng’rs, 
    702 F.3d 1156
    , 1166 (10th Cir. 2012). With certain exceptions, the CWA
    prohibits the “discharge of dredged or fill material into the” “waters of the United
    States.” 33 U.S.C. §§ 1311(a), 1344(a), 1362(7). But the Corps “may issue permits, after
    notice and opportunity for public hearings for the discharge of dredged or fill material
    into the navigable waters at specified disposal sites.” 
    Id. § 1344(a).
    This permitting
    process is governed by the Section 404(b)(1) Guidelines, which are contained in Part 230
    of Title 40 of the Code of Federal Regulations. 40 C.F.R. §§ 230.1–230.98. When the
    Corps decides whether it may itself “discharge[] . . . dredged material or fill material,” it
    does not issue a permit, “but does apply the 404(b)(1) [G]uidelines and other substantive
    requirements of the CWA and other environmental laws.” 33 C.F.R. § 335.2.
    The 404(b)(1) Guidelines state that “no discharge of dredged or fill material shall
    be permitted if there is a practicable alternative to the proposed discharge which would
    have less adverse impact on the aquatic ecosystem, so long as the alternative does not
    have other significant adverse environmental consequences.” 40 C.F.R. § 230.10(a).
    “An 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.”
    
    Id. § 230.10(a)(2).
    In other words, the Corps may authorize a proposed discharge when it
    5
    is the least environmentally damaging practicable alternative (“LEDPA”). 
    Id. § 230.10(a).
    B.     Factual Background
    In 1973, the Corps constructed the Chatfield Reservoir by erecting a dam across
    the South Platte River southwest of Denver. PAA0643. The Reservoir was primarily
    built for flood control, but Congress also authorized the Corps to develop recreational
    facilities at the Reservoir. PAA0643–44. In 1974, the Corps leased the land surrounding
    the Reservoir to the State of Colorado, which opens the area to the public as Chatfield
    State Park. PAA0644. Chatfield State Park is currently one of the most popular state
    parks in Colorado. PAA0628–29.
    In 1986, Congress authorized the Corps to study whether it would be feasible and
    economically justifiable to reallocate part of Chatfield Reservoir’s storage capacity from
    flood control to municipal, industrial, and agricultural water storage. See Water Resource
    Development Act of 1986, Pub. L. No. 99-662, § 808, 100 Stat. 4082, 4186. The
    resulting study predicted that, even taking into account water conservation programs,
    water providers will need approximately 50% more water in 2050 because of population
    growth in the Denver metropolitan area. PAA0629–30, 0656, 0658. Under current
    conditions, absent the development of additional water supply, the Denver metropolitan
    area will have “approximately 90,000 acre-feet of unmet [water] needs” in 2050.
    PAA0658. In 2009, Congress “authorized . . . modifications of the . . . [Chatfield]
    Reservoir, . . . and any required mitigation,” to accommodate water storage. Omnibus
    Appropriations Act of 2009, Pub. L. No. 111-8, § 116, 123 Stat. 524, 608.
    6
    Following additional study, a group of water providers who supply water to
    municipal, industrial, and agricultural users in the Denver metropolitan area proposed the
    Reallocation Project at issue in this appeal. PAA0665. The Reallocation Project allows
    the water providers to store 20,600 acre-feet of water in Chatfield Reservoir. PAA0665.
    The immediate practical effect of the Reallocation Project is that the maximum water
    level in the Reservoir will rise by 12 feet, flooding 587 acres of Chatfield State Park.
    PAA0764. The flooded area includes various recreation facilities and sensitive
    environments. PAA0765, 0827–30. Because of these effects, the water providers also
    proposed two plans—one to relocate the recreation facilities and the other to mitigate
    environmental damage. PAA0828–40. As proposed, the recreation relocation and
    environmental mitigation plans involved the discharge of dredged and fill material into
    wetlands near Chatfield Reservoir. 1 PAA0840.
    As part of its review of the Reallocation Project, the Corps prepared an
    Environmental Impact Statement. PAA0627. The EIS states that “the main problem”
    addressed by the Reallocation Project is the “increasing water demand in the Denver
    Metro area that exceeds available water supplies.” PAA0628. Accordingly,
    [t]he purpose and need [of the Reallocation Project] is to increase
    availability of water, providing an additional average year yield of
    up to approximately 8,539 acre-feet of municipal and industrial . . .
    water, sustainable over the 50-year period of analysis, in the greater
    Denver Metro area so that a larger proportion of existing and future
    water needs can be met.
    1
    Fill material, which would be deposited in certain areas of wetlands around Chatfield
    Reservoir to raise parts of the shoreline above the new high water line, would be
    excavated from five sites around Chatfield State Park. PAA1083-87.
    7
    PAA0628. The Corps also noted that any version of the Reallocation Project ultimately
    approved would need to comply with the CWA, mitigate any environmental damage
    caused by the Reallocation Project, and preserve recreation opportunities for Chatfield
    State Park visitors. PAA0662–63.
    The Corps initially examined thirty-eight alternatives for securing additional water
    supply for the Denver metropolitan area. PAA0667. These strategies fell into seven
    categories: increased water conservation, agricultural transfers, importation of water,
    development of new water storage facilities, storage of additional water at existing
    reservoirs, increased use of surface water and groundwater, and increased water
    recycling. 2 PAA0667–71. The Corps used four criteria to compare these potential
    alternatives: “[a]bility to meet purpose and need,” “[c]ost,” “[l]ogistics and technology,”
    and “[e]nvironmental impacts (including significance and ability to mitigate).”
    PAA0633–34. After its initial analysis, the Corps concluded that some of the original
    thirty-eight alternatives did not warrant further study. Among those alternatives
    abandoned by the Corps were increased water conservation, development of gravel pit
    storage upstream from Chatfield Reservoir, and the purchase of water storage capacity at
    the Rueter-Hess Reservoir. PAA0673, 0689. After briefly explaining its decision not to
    further analyze thirty-four alternatives, the Corps considered the remaining four
    alternatives in detail.
    2
    The surface water would be captured from above-ground streams or rivers, PAA0682,
    and groundwater would be pumped from underground aquifers, PAA0743-44.
    8
    First, the Corps considered Alternative 1, the “No Action Alternative,” which
    meant the Reallocation Project would not proceed and water providers would have to
    look to other options to secure additional water. PAA0693. “The main feature of the No
    Action Alternative is the development of other alternative surface storage units to contain
    surface water supplies of the same approximate yield of the Chatfield Reservoir storage
    reallocation project.” PAA0693. Specifically, the No Action Alternative assumed that
    the water providers would store surface water in a newly-constructed Penley Reservoir
    and downstream gravel pits. PAA0693.
    The Corps next considered Alternative 2, in which the water providers would meet
    future demand using groundwater and surface water stored in downstream gravel pits.
    PAA0714–15. The gravel pits in Alternative 2 would be developed in the same way as in
    Alternative 1. PAA0715. But in Alternative 2, instead of building Penley Reservoir, the
    water providers would also rely on groundwater to serve their customers. PAA0715.
    The Corps then evaluated Alternative 3, which is the Reallocation Project that was
    ultimately selected. PAA0715–16. Under Alternative 3, the water providers could store
    20,600 acre-feet of water in Chatfield Reservoir. PAA0715. Increasing the amount of
    water in Chatfield Reservoir would raise the water level by 12 feet. PAA0715. “No new
    infrastructure would be needed at Chatfield by any water provider.” PAA0716.
    Finally, the Corps examined Alternative 4, which would allow water providers to
    store 7,700 acre-feet of water in Chatfield Reservoir. PAA0716–17. Alternative 4 would
    increase the water level in the reservoir by five feet. PAA0717. To meet additional
    demand, the water providers would also rely on groundwater and surface water stored in
    9
    downstream gravel pits (again developed in the same way as in Alternative 1).
    PAA0717.
    After comparing these four alternatives, the Corps chose Alternative 3. PAA0819.
    The Corps concluded that “Alternative 3 maximizes [National Economic Development]
    benefits” by “minimiz[ing] the cost of supplying water” and “best meets the water supply
    needs of the water providers.” PAA0819. The Corps also concluded that
    Alternative 3 is . . . the Least Environmentally Damaging alternative
    because: 1) the environmental impacts of Alternative 3 at Chatfield
    can all be fully mitigated; 2) Alternative 3 does not result in the
    drying up of any farmland or include the use of non-renewable
    [groundwater]; and 3) Alternative 3 is the plan most consistent with
    the Corps’ seven [Environmental Operating Principles].
    PAA0819.
    While conducting the NEPA analysis, the Corps remained mindful that the
    alternative ultimately chosen would need to comply with the CWA. PAA0663.
    Alternative 3 includes “the modification of recreation facilities and certain environmental
    mitigation activities [that] would involve the discharge of dredge and fill material into
    waters of the United States, including wetlands.” PAA0840. “These discharge activities
    would involve an estimated temporary impact to about 5.5 acres of wetlands and a loss of
    about 6.9 acres of wetlands.” 
    Id. In the
    Corps’ opinion, the “[c]umulative impacts of the
    proposed dredge and fill activities on the aquatic ecosystem are expected to be small.”
    PAA0842.
    The Corps also appended a separate analysis of the dredge and fill discharge
    associated with the Reallocation Project. PAA1072–1101. As part of that analysis, the
    10
    Corps considered whether it could relocate the recreation facilities and mitigate
    environmental damage without discharging dredge or fill. PAA1094, 1097. The Corps
    concluded that, while it was possible to avoid discharging dredge or fill, doing so “would
    result in a greater area of net disturbance and environmental impact,” PAA1095; prevent
    the Corps from fully replacing the recreational facilities affected by plan; and
    “complicate the construction, maintenance, and reliability of the [environmental]
    mitigation,” PAA1098. Because of these complications, the Corps instead modified the
    recreation relocation and environmental mitigation plans to “avoid[] and minimize[] the
    discharge of fill material . . . to the maximum extent practicable while still meeting the
    objective[s] of providing recreation facilities that maintain the existing recreational
    experience,” PAA1097, and “fully mitigating the [environmental] impacts,” PAA1098.
    In May 2014, the Corps issued its Record of Decision approving the Reallocation
    Project. PAA1144–45. In October 2014, Audubon sought review of the Corps’ decision.
    The Colorado Department of Natural Resources and the water providers who seek to
    store water in Chatfield Reservoir intervened in support of the Corps’ decision.
    PAA0006. Audubon moved to supplement the administrative record. PAA0131–54.
    The district court denied the motion because it found that the administrative record was
    sufficient for the Corps’ analysis. PAA0277–88. In December 2017, the district court
    concluded that the Corps did not act arbitrarily or capriciously when approving the
    Reallocation Project and affirmed the Corps’ decision. PAA0500–38. Audubon timely
    filed a notice of appeal. PAA0543–45.
    11
    Audubon then moved in this Court for an injunction pending appeal because the
    Corps has already begun to implement the Reallocation Project. The motion was denied.
    Audubon subsequently filed a motion to expedite consideration of this appeal because of
    the ongoing construction at Chatfield Reservoir. The motion was denied as premature
    because the appeal was not yet fully briefed. After filing its reply brief, Audubon again
    moved for expedited consideration. The motion was denied insofar as it sought a special
    sitting to hear the appeal, and deferred insofar as it sought expedited consideration after
    oral argument.
    II
    Audubon challenges the Corps’ compliance with NEPA and the CWA. We
    review the district court’s decision de novo and “the Corps’ compliance with NEPA and
    the CWA pursuant to the Administrative Procedure Act.” Greater Yellowstone Coal. v.
    Flowers, 
    359 F.3d 1257
    , 1268 (10th Cir. 2004). Under the APA, we will not set aside the
    Corps’ decision unless it is “arbitrary, capricious, an abuse of discretion, or otherwise not
    in accordance with law.” 5 U.S.C. § 706(2)(A). “The APA’s arbitrary and capricious
    standard is a deferential one; administrative determinations may be set aside only for
    substantial procedural or substantive reasons, and the court cannot substitute its judgment
    for that of the agency.” Utahns for Better Transp. v. U.S. Dep’t of Transp., 
    305 F.3d 1152
    , 1164 (10th Cir. 2002).
    A.     NEPA
    NEPA requires the Corps to prepare an EIS for a “major Federal action[]
    significantly affecting the quality of the human environment.” 42 U.S.C. § 4332(C).
    12
    When an agency prepares an EIS, it must “[r]igorously explore and objectively evaluate
    all reasonable alternatives” to the project. 40 C.F.R. § 1502.14(a). But “[a] rule of
    reason applies to an . . . agency’s choice of alternatives to include in its analysis.”
    WildEarth Guardians v. Nat’l Park Serv., 
    703 F.3d 1178
    , 1183 (10th Cir. 2013)
    (quotation marks omitted).
    “[A]gencies are not required to consider alternatives they have in good faith
    rejected as too remote, speculative, or impractical or ineffective.” 
    Id. (quotation marks
    and ellipsis omitted). “Alternatives that do not accomplish the purpose of an action are
    not reasonable, and need not be studied in detail by the agency.” 
    Id. (quotation marks
    omitted). Moreover, “an agency has wide discretion in defining its objectives and in
    determining which alternatives meet those objectives.” W. Watersheds Project v. Bureau
    of Land Mgmt., 
    721 F.3d 1264
    , 1275–76 (10th Cir. 2013). When an agency decides to
    exclude an alternative from detailed study, it only needs to “‘briefly discuss the reasons’
    for eliminating [the] unreasonable alternative[] from [the] EIS.” 
    WildEarth, 703 F.3d at 1183
    (quoting 40 C.F.R. § 1502.14(a)).
    Audubon argues that the Corps dismissed three alternatives without sufficient
    explanation. 3 Aplt. Br. 44. Specifically, Audubon faults the Corps for failing to examine
    3
    At oral argument, Audubon also argued that the Reallocation Project does not increase
    water supply for the Denver metropolitan area because the Reallocation Project has “zero
    dependable yield.” Because this issue was not briefed by the parties, we asked them to
    file notices of supplemental authority pursuant to Federal Rule of Appellate Procedure
    28(j). In the EIS, the Corps acknowledged that, under the Reallocation project, the water
    providers will store varying amounts of water from year to year because the water
    providers have relatively junior water rights. PAA0973, 1069. The water providers will
    store less in drought years and more in years when water is abundant. But these
    13
    “[e]nhanced water conservation measures,” which “go beyond the standard methods
    already being used by water providers.” Aplt. Br. 45–50. Audubon also maintains that
    the Corps erred when it excluded upstream gravel pits from further consideration because
    they offered sufficient capacity for the Reallocation Project. Aplt. Br. 50–53. Finally,
    Audubon asserts that the water providers could have purchased storage capacity at the
    Rueter-Hess Reservoir instead of expanding the Chatfield Reservoir. Aplt. Br. 53–55.
    We hold that the Corps’ decision not to further analyze these three alternatives was not
    arbitrary or capricious.
    First, the Corps considered increased water conservation at length and concluded
    that “water conservation is not an equivalent practicable alternative to the proposed
    project” because the “shortages of sustainable water supplies faced by the water providers
    will not be resolved by water conservation measures alone.” PAA0674. Instead, the
    Corps’ subsequent analyses assumed that “[c]urrent water conservation practices
    constitute an independent parallel action” to the Reallocation Project. PAA0679. As the
    Corps explained in response to a public comment, “[w]ater conservation goals and
    amounts were considered when determining the amount of water needed for future use.”
    fluctuations are not caused by the Reallocation Project, but by the natural cycle of
    drought. As the Corps explained, “[b]ecause gravel pit or reservoir storage relies on
    junior surface water rights, the water supply for all alternatives, to some degree, would be
    unreliable during dry periods.” PAA0813. The Corps also explained that Chatfield
    Reservoir is an attractive storage option because it sits on the South Platte River and can
    effectively capture excess water without new facilities. PAA0973. Therefore, Audubon
    has less raised a problem with the Reallocation Project than noted the challenge faced by
    water suppliers as they attempt to serve the growing needs of the Denver metropolitan
    area with erratic surface water availability.
    14
    PAA0971. Therefore, the Corps “view[ed] each alternative [discussed in the EIS] as also
    including the various conservation programs as components.” PAA0971.
    The Corps concluded that, while “conservation can delay the timing of the need
    for additional supplies,” “it does not in itself eliminate the need for additional supplies.”
    PAA0673. Contrary to Audubon’s suggestion, Aplt. Br. 46–50, Davis v. Mineta, 
    302 F.3d 1104
    , 1122 (10th Cir. 2002), abrogated on other grounds by Dine Citizens Against
    Ruining Our Env’t v. Jewell, 
    839 F.3d 1276
    (10th Cir. 2016), does not indicate that the
    Corp’s analysis was inadequate. In Davis, the agency’s NEPA analysis was deficient
    because it “summarily rejected” alternatives that could not, “standing alone,” achieve the
    project’s 
    goals. 302 F.3d at 1120
    . The Department of Transportation made “no effort” to
    consider whether these alternatives, when analyzed “in conjunction” with each other,
    could achieve the project goals. 
    Id. at 1121.
    The Corps’ analysis here is far more
    extensive. The Corps thoroughly described the current status of the water providers’
    conservation plans and explained that, because the future unmet water need is so great,
    the water providers will “develop even more stringent water conservation measures,”
    even after the Reallocation Project is completed. PAA0673–0679, 0944–0961. This
    discussion sufficiently explained why the Corps did not consider enhanced water
    conservation to be a reasonable alternative worthy of further analysis, which is all that
    NEPA requires. See 
    WildEarth, 703 F.3d at 1183
    –87.
    Second, the Corps adequately explained why upstream gravel pits did not merit
    further discussion. Upstream gravel pits were “eliminated from further consideration due
    to limited storage capacity and the logistical difficulties of combining reservoirs to meet
    15
    the storage requirements of the project.” PAA0683. The upstream gravel pits had 5,490
    acre-feet of capacity spread across three reservoirs, which was less than the 8,539 acre-
    feet sought by the Reallocation Project. PAA0669. On the other hand, downstream
    gravel pits, which the Corps did analyze at length, would have provided 7,835 acre-feet
    of storage and presented fewer logistical complications. PAA0700. Compared to the
    upstream gravel pits, the downstream gravel pits were closer to “existing water supply
    system[s],” which “minimize[d] connection costs” for the water suppliers. PAA0700.
    Given that the upstream and downstream gravel pits were similar alternatives, but the
    downstream option offered more storage at a lower cost, the Corps’ decision to exclude
    upstream gravel pits as an alternative was neither arbitrary nor capricious. Prairie Band
    Pottawatomie Nation v. Fed. Highway Admin., 
    684 F.3d 1002
    , 1011 (10th Cir. 2012)
    (“[A]n agency need not consider an alternative unless it is significantly distinguishable
    from the alternatives already considered.” (quotation marks omitted)).
    Notwithstanding the Corps’ reasoning, Audubon urges us to conclude that the
    Corps’ analysis was arbitrary and capricious because, after the Corps finalized the EIS,
    an upstream gravel pit owner informed the Corps that a “preliminary” report showed that
    the pit could “hav[e] the capacity for 11,000 acre-feet of storage when expanded.”
    PAA1105. This new information does not render the Corps’ decision arbitrary or
    capricious because the information was not provided to the Corps until after the final EIS
    was issued. Prairie 
    Band, 684 F.3d at 1012
    –13.
    Third, the Corps sufficiently explained why storing water at the Rueter-Hess
    Reservoir was not a viable alternative to the Reallocation Project. The Corps observed
    16
    that the Rueter-Hess “[w]ater allocation [had been] subscribed and permitted under a
    separate planning action” carried out by the Corps. PAA0670. The Corps further noted
    that several water providers already owned the “storage capacity” at the Rueter-Hess
    Reservoir. PAA0670. Though the Rueter-Hess Reservoir had recently been expanded,
    the capacity was “anticipated to primarily meet the needs of” the current storage owners,
    who “ha[d] not made any additional [storage] capacity available for sale” since 2012.
    PAA0684. The Corps explained that storing additional water at Rueter-Hess was not a
    practicable alternative because there was no available storage in that reservoir. This
    analysis was not arbitrary or capricious. 4 See 
    WildEarth, 703 F.3d at 1183
    –87.
    B.     CWA
    The CWA authorizes the Corps to “issue permits, after notice and opportunity for
    public hearings for the discharge of dredged or fill material into the navigable waters at
    specified disposal sites.” 33 U.S.C. § 1344(a). Regulations implementing the CWA state
    that “no discharge of dredged or fill material shall be permitted if there is a practicable
    alternative to the proposed discharge which would have less adverse impact on the
    aquatic ecosystem, so long as the alternative does not have other significant adverse
    environmental consequences.” 40 C.F.R. § 230.10(a). “An alternative is practicable if it
    4
    Audubon asks that we take judicial notice of the Parker Water and Sanitation District’s
    website for “the fact that, at this time, Rueter-Hess Reservoir is only 1/3 full.” Aplt.
    Reply Br. at 26 n.10. Even if the accuracy of this statement was sufficiently certain to
    warrant our taking judicial notice of it, the statement does not speak to the question of
    whether any of the storage capacity in the Reservoir is for sale.
    17
    is available and capable of being done after taking into consideration cost, existing
    technology, and logistics in light of overall project purposes.” 5 
    Id. § 230.10(a)(2).
    The Corps interpreted the phrase “practicable alternative to the proposed
    discharge” to limit the scope of its CWA alternatives analysis to those portions of the
    Reallocation Project that caused the discharge of dredge and fill. 6 Aple. Br. 27. The
    Corps reasoned that the entire Reallocation Project could be accomplished without the
    discharge of dredge and fill because (1) increasing the water level in Chatfield Reservoir
    causes no discharge and (2) it was possible to “totally avoid all discharge of fill material”
    when relocating the recreation facilities and mitigating environmental damage.
    PAA1074, 1095. But when the water providers actually proposed the recreation
    relocation and environmental mitigation plans, each plan called for the discharge of
    dredge and fill. PAA1094–98. Because the Corps did not consider these proposed
    discharges to be integral to the Reallocation Project—i.e., the Corps could have approved
    5
    “Where the activity associated with a discharge [into] . . . a special aquatic site . . . does
    not require access or proximity to or siting within the special aquatic site in question to
    fulfill its basic purpose (i.e., is not water dependent), practicable alternatives that do not
    involve special aquatic sites are presumed to be available, unless clearly demonstrated
    otherwise.” 40 C.F.R. § 230.10(a)(3). Wetlands are a special aquatic site. 
    Id. § 230.41.
    No party discusses whether the § 230.10(a)(3) presumption applies in this case, and it
    does not appear that the Corps explicitly determined whether the recreation relocation
    and environmental mitigation plans were water dependent. The district court noted this
    issue and concluded that the presumption was “not at issue” in this case. PAA0530.
    6
    During the preparation of the EIS, there was debate within the Corps and with the
    Environmental Protection Agency about whether the Corps had adopted the correct
    interpretation of 40 C.F.R. § 230.10(a). PAA1056–66, 1152–1153, 1157–1164. After
    further discussion, the EPA became “comfortable with the approach taken by the Corps
    in the preliminary draft CWA § 404(b)(1) analysis.” PAA1066. Because we “are
    empowered to review only an agency’s final action,” this internal debate does not render
    the Corp’s ultimate interpretation arbitrary or capricious. Nat’l Ass’n of Home Builders
    v. Defs. of Wildlife, 
    551 U.S. 644
    , 659 (2007) (citing 5 U.S.C. § 704).
    18
    the Reallocation Project without allowing the discharge of dredge and fill—the Corps
    limited its CWA analysis to the water providers’ recreation relocation and environmental
    mitigation plans. PAA0840–42, 1072–1101.
    Audubon disagrees with the Corps’ interpretation of 40 C.F.R. § 230.10(a).
    Audubon argues that the Corps should have used the 404(b)(1) Guidelines to compare the
    four NEPA alternatives to the Reallocation Project, not just the alternatives to the
    recreation relocation and environmental mitigation plans. Aplt. Br. 28–30. According to
    Audubon, the suggestion in § 230.10(a)(2) that alternatives be considered “in light of
    overall project purposes” means that the CWA analysis should focus on the project as a
    whole, not just “the proposed discharge.” Aplt. Br. 28–30. Therefore, Audubon argues
    that the Corps improperly segmented the Reallocation Project when it analyzed
    alternatives to the recreation relocation and environmental mitigation plans without
    accounting for the environmental impacts of the rest of the Reallocation Project. Aplt.
    Br. 28–30.
    Resolving this dispute involves two questions. See Biodiversity Conservation All.
    v. Jiron, 
    762 F.3d 1036
    , 1062–69 (10th Cir. 2014). The first asks whether the Corps
    correctly interpreted its own regulation. 
    Id. at 1062.
    The second asks whether the Corps
    “compl[ied] with its own interpretation.” 
    Id. at 1069.
    We address each question in turn.
    When deciding whether an agency correctly interpreted its own regulations, “we
    . . . determine whether the language at issue has a plain and unambiguous meaning with
    regard to the particular dispute in the case.” 
    Id. at 1062
    (quotation marks omitted). If so,
    we apply the regulation’s unambiguous meaning. 
    Id. But “[i]f
    the meaning is
    19
    ambiguous, we defer to [the] agency’s interpretation . . . , even when that interpretation is
    advanced in a legal brief, unless the agency’s interpretation is plainly erroneous or
    inconsistent with the regulation.” 
    Id. (quotation marks
    and citations omitted). “An
    agency’s interpretation need not be the only possible reading of a regulation—or even the
    best one—to prevail.” 
    Id. (quotation marks
    and alteration omitted).
    Section 230.10(a) does not plainly and unambiguously define the scope of the
    Corps’ CWA analysis. Whereas § 230.10(a) is narrowly focused on “the proposed
    discharge,” § 230.10(a)(2) instructs the Corps to take into account the “overall project
    purposes.” The Corps proposes an interpretation of § 230.10(a) in which the scope of its
    CWA analysis is determined by the relationship between the overall project and the
    proposed discharge. Under the Corps’ interpretation, when the proposed discharge is
    incidental to the completion of the overall project, the Corps’ analysis must only address
    alternatives to the proposed discharge.
    The Eighth and Ninth Circuits have affirmed the issuance of dredge and fill
    permits when the Corps employed a similar interpretation of § 230.10(a). See Nat’l
    Wildlife Fed’n v. Whistler, 
    27 F.3d 1341
    , 1345–46 (8th Cir. 1994) (reasoning that the
    Corps was faced with “two severable projects” where one “would proceed even without”
    the § 404 permit); Sylvester v. U.S. Army Corps of Eng’rs (Sylvester II), 
    882 F.2d 407
    ,
    410–11 (9th Cir. 1989) (“[A]n alternative site does not have to accommodate components
    of a project that are merely incidental to the applicant’s basic purpose.”). 7 As Audubon
    7
    In Sylvester, a developer planned to build a resort on uplands and a golf course on
    wetlands. Sylvester 
    II, 882 F.2d at 410
    –11. “The Corps believed that it had jurisdiction
    20
    notes, the Corps’ interpretation of § 230.10(a) could incentivize permit applicants to
    improperly segment their projects to minimize apparent environmental damage. Aplt. Br.
    32–34. But we have previously addressed similar concerns by explaining that the Corps
    can only consider an applicant’s “legitimate” objectives when defining the scope of its
    CWA analysis. Greater 
    Yellowstone, 359 F.3d at 1269
    –70 (citing Sylvester 
    II, 882 F.2d at 409
    , and 
    Whistler, 27 F.3d at 1346
    ). “[A]n applicant cannot define a project in order to
    preclude the existence of any alternative sites and thus make what is practicable appear
    impracticable.” 8 
    Whistler, 27 F.3d at 1346
    (quoting Sylvester 
    II, 882 F.2d at 409
    ).
    only over the wetlands and, accordingly, confined its review to the meadow where [the
    developer] intend[ed] to locate the golf course.” Sylvester v. U.S. Army Corps of Eng’rs
    (Sylvester I), 
    884 F.2d 394
    , 396 (9th Cir. 1989). In Whistler, a developer planned to build
    a housing development on uplands and provide water access to the development by
    dredging 
    wetlands. 27 F.3d at 1345
    –46. The Corps analyzed the two components of the
    project separately because “the planned housing development site was located on uplands
    and therefore could proceed without a permit.” 
    Id. at 1345.
    8
    Without citing any authority, Audubon suggests that the Corps should apply NEPA’s
    anti-segmentation rule to its CWA analyses. Aplt. Br. 32–34. The anti-segmentation rule
    is designed “to prevent agencies from minimizing the potential environmental
    consequences of a proposed action (and thus short-circuiting NEPA review) by
    segmenting or isolating an individual action that, by itself, may not have a significant
    environmental impact.” Citizens’ Comm. to Save Our Canyons v. U.S. Forest Serv., 
    297 F.3d 1012
    , 1028 (10th Cir. 2002). But, as discussed previously, NEPA and the CWA
    have distinct analytical frameworks. See 
    Hillsdale, 702 F.3d at 1165
    –66 (comparing an
    agency’s obligations under NEPA and the CWA). Audubon argues that the same policy
    considerations motivate NEPA and the CWA, but this argument does not address the fact
    that Congress enacted two statutes, each with its own unique procedure. See Wyoming v.
    U.S. Dep’t of Agric., 
    661 F.3d 1209
    , 1239 (10th Cir. 2011) (“To impose upon the agency
    more stringent requirements than the legal framework requires, absent extremely
    compelling circumstances, would violate the well-settled principle articulated by the
    Supreme Court in Vermont Yankee that the formulation of procedure is to be basically left
    within the discretion of the agencies to which Congress has confined the responsibility
    for substantive judgments.” (quotation marks omitted) (referring to Vermont Yankee
    Nuclear Power Plant v. Nat. Res. Def. Council, 
    435 U.S. 519
    (1978))).
    21
    In addition to finding support in prior case law, the Corps’ interpretation of
    § 230.10(a) is supported by other parts of the 404(b)(1) Guidelines. The Corps is
    “instruct[ed] . . . to ‘recognize the different levels of effort that should be associated with
    varying degrees of impact [from the proposed discharge] and require or prepare
    commensurate documentation.’” Greater 
    Yellowstone, 359 F.3d at 1271
    (quoting 40
    C.F.R. § 230.6(b)). “The level of documentation should reflect the significance and
    complexity of the discharge activity.” 40 C.F.R. § 230.6(b). Though the Corps must
    always identify the LEDPA, “the compliance evaluation procedures will vary to reflect
    the seriousness of the potential for adverse impacts on the aquatic ecosystems posed by
    specific dredged or fill material discharge activities.” Greater 
    Yellowstone, 359 F.3d at 1271
    (quoting 40 C.F.R. § 230.10). These provisions support the Corps’ interpretation of
    § 230.10(a) because they instruct the Corps to consider the scale of a proposed discharge
    when applying the 404(b)(1) Guidelines.
    Other provisions of the 404(b)(1) Guidelines similarly confirm that the Corps’
    CWA and NEPA analyses can differ in scope. Audubon correctly argues, Aplt. Br. 42,
    that “the analysis of alternatives required for NEPA environmental documents[] . . . will
    in most cases provide the information for the evaluation of alternatives under” the
    404(b)(1) Guidelines. 40 C.F.R. § 230.10(a)(4). But the Guidelines also state that, “[o]n
    occasion, these NEPA documents may address a broader range of alternatives than
    required to be considered under [the CWA] or may not have considered the alternatives
    in sufficient detail to respond to the requirements of” the 404(b)(1) Guidelines. 
    Id. 22 Because
    the Corps’ interpretation of § 230.10(a)—that its analysis need only
    address alternatives to the proposed discharge when the proposed discharge is incidental
    to the completion of the overall project—finds support in case law and other parts of the
    404(b)(1) Guidelines, its interpretation is not “plainly erroneous or inconsistent with the
    regulation.” Biodiversity Conservation 
    All., 762 F.3d at 1068
    –69. Accordingly, we now
    consider whether the Corps complied with its own interpretation of § 230.10(a).
    We conclude that the Corps complied with § 230.10(a) because it reasonably
    found that it could approve the Reallocation Project without allowing the discharge of
    dredge and fill, PAA1095–97, such that it was appropriate for the Corps to confine its
    CWA analysis to the recreation relocation and environmental mitigation plans, see
    
    Whistler, 27 F.3d at 1345
    –46; Sylvester 
    II, 882 F.2d at 410
    –11. The Corps explained in
    the EIS that it was “feasible” to complete the recreation relocation and environmental
    mitigation plans without discharging dredge and fill. PAA1095–96. As part of its
    analysis, the Corps explained how the plans could be amended to avoid the discharge of
    dredge and fill. PAA1095–96. Potential changes included moving “recreational facilities
    . . . farther from the reservoir,” PAA1135, shortening culverts, PAA1138, and positioning
    “stilling basins . . . outside of wetlands,” PAA1138. Audubon disputes the Corps’
    conclusion, but provides no reasoned basis to doubt the Corps’ explanation that dredge
    and fill could be avoided if the recreation facilities and mitigation activities were moved
    farther from the wetlands. Aplt. Reply Br. 7 n.2; PAA1095–96.
    Audubon does not suggest that the Corps defined the objectives of the recreation
    relocation and environmental modification plans to circumvent the CWA, nor is there any
    23
    indication in the record of such gamesmanship. The objectives of these plans were,
    respectively, “providing recreation facilities that maintain the existing recreational
    experience” and “fully mitigating the impacts to wetlands, riparian habitat, Preble’s
    habitat, and bird habitat impacted by the [Reallocation] Project.” PAA1097–98. The
    Corps repeatedly noted throughout the EIS that these were also objectives of the
    Reallocation Project. PAA0649, 0661, 0663. The objectives are also rooted in the
    Congressional authorization of the Reallocation Project. See § 116, 123 Stat. at 608
    (“authoriz[ing] . . . modifications of the facility (Chatfield Reservoir, Colorado), and any
    required mitigation which results from implementation of the project”). Most
    importantly, the Corps’ definition of the objectives did not “preclude the existence of any
    alternative sites and thus make what is practicable appear impracticable.” 
    Whistler, 27 F.3d at 1346
    (quoting Sylvester 
    II, 882 F.2d at 409
    ).
    Even after the Corps limited its analysis to the recreation relocation and
    environmental mitigation plans, it sufficiently analyzed the alternatives and identified the
    LEDPA. During its CWA analysis, the Corps considered the plans as originally proposed
    by the water providers, as well as alternatives that would have involved no discharge of
    dredge or fill. “While [the no discharge] approach [wa]s . . . feasible,” the Corps
    concluded that “it would result in a greater area of net disturbance and environmental
    impact, and a significant reduction of the amount of desired in-kind replacement of
    existing recreational amenities and experiences.” PAA1095. The no discharge approach
    was also more expensive. PAA1096. The Corps settled on a compromise alternative that
    24
    “would involve an estimated temporary impact to about 5.5 acres of wetlands and a loss
    of about 6.9 acres of wetlands.” PAA0840.
    As approved, the recreation relocation and environmental mitigation plans
    “avoid[] and minimize[] the discharge of fill material” “to the maximum extent
    practicable” while still achieving the Corps’ objectives. PAA1097–98. The Corps
    explained that, as a result, the “[c]umulative impacts of the proposed dredge and fill
    activities on the aquatic ecosystem are expected to be small.” PAA1100. According to
    the EIS, relocating the recreation facilities “would have little effect on the aquatic
    ecosystem due to limited dredge and fill footprints.” PAA1100. The Corps also found
    that the environmental mitigation would not “impact[] . . . long-term water quality or the
    aquatic ecosystem” and would cause “the benefit of improved sediment erosion control.”
    PAA1100. Moreover, the negative impacts to wetlands will themselves “be fully
    mitigate[d].” PAA1100. Therefore, the Corps’ decision to approve the recreation
    relocation and environmental mitigation plans, as modified to reduce dredge and fill, was
    not arbitrary or capricious.
    C.     Motion to Supplement the Record
    “We review a district court’s determination of whether or not to exclude extra-
    record evidence for abuse of discretion.” Citizens for Alts. To Radioactive Dumping v.
    U.S. Dep’t of Energy, 
    485 F.3d 1091
    , 1096 (10th Cir. 2007). “[J]udicial review of
    agency action is normally restricted to the administrative record, [but] we have
    recognized that consideration of extra-record materials is appropriate in extremely limited
    circumstances, such as where the agency ignored relevant factors it should have
    25
    considered or considered factors left out of the formal record.” Lee v. U.S. Air Force,
    
    354 F.3d 1229
    , 1242 (10th Cir. 2004) (quotation marks omitted). “[W]here, as is often
    the case in the NEPA context, we are faced with an agency’s technical or scientific
    analysis, an initial examination of the extra-record evidence . . . may illuminate whether
    an EIS has neglected to mention a serious environmental consequence, failed adequately
    to discuss some reasonable alternative, or otherwise swept stubborn problems or serious
    criticism under the rug.” 
    Id. (quotation marks
    and alteration omitted).
    Audubon argues that the district court abused its discretion by denying the motion
    to supplement the record because the administrative “record lacks documentation
    required to determine if the Corps’ dismissal of Rueter-Hess Reservoir and enhanced
    water conservation measures . . . was justified.” Aplt. Br. 57. Audubon claims that
    consideration of a water conservation survey was necessary for the Corps to determine
    whether enhanced water conservation was a viable alternative to the Reallocation Project.
    Aplt. Br. 58 (referring to PAA0201). Audubon also claims that a report on a water
    recycling program (Project WISE) was necessary for the Corps to properly evaluate the
    viability of storing additional water in the Rueter-Hess Reservoir. Aplt. Br. 59–61
    (referring to PAA0225–41).
    The district court denied Audubon’s motion because neither the survey of water
    conservation efforts nor the Project WISE information indicated that the Corps’ NEPA
    analysis was deficient. PAA0284–87. The district court reasoned that water
    conservation efforts, including potential efforts to enhance water conservation in the
    future, were extensively discussed in the EIS. PAA0285–87. The district court also
    26
    explained that the summary of Project WISE was addressed in the NEPA alternatives
    analysis when the Corps stated that Rueter-Hess did not have any storage capacity for
    sale and that Project WISE was an independent effort to increase water supply in the
    Denver metropolitan area. PAA0284–85, 0671, 0685, 0688.
    The district court did not abuse its discretion in denying Audubon’s motion to
    supplement the record. Rather, it correctly noted that the EIS already incorporated
    sufficient information about water conservation in Colorado and the impact of Project
    WISE on regional water supply. Therefore, the extra record evidence would not have
    filled “gaps” or addressed “inadequacies” in the Corps’ analysis. 
    Lee, 354 F.3d at 1242
    .
    III
    Because the Corps’ approval of the Reallocation Project was neither arbitrary nor
    capricious, and the district court’s denial of Audubon’s motion to supplement the record
    was not an abuse of discretion, we AFFIRM. Audubon’s motion for an expedited
    decision is DENIED as moot.
    27