Florida v. Georgia , 201 L. Ed. 2d 871 ( 2018 )


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  • (Slip Opinion)              OCTOBER TERM, 2017                                       1
    Syllabus
    NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
    being done in connection with this case, at the time the opinion is issued.
    The syllabus constitutes no part of the opinion of the Court but has been
    prepared by the Reporter of Decisions for the convenience of the reader.
    See United States v. Detroit Timber & Lumber Co., 
    200 U.S. 321
    , 337.
    SUPREME COURT OF THE UNITED STATES
    Syllabus
    FLORIDA v. GEORGIA
    ON EXCEPTIONS TO REPORT OF SPECIAL MASTER
    No. 142, Orig. Argued January 8, 2018—Decided June 27, 2018
    This original action concerns the proper apportionment of water from
    an interstate river basin. Three rivers form the heart of the Basin.
    The Chattahoochee and Flint Rivers begin near Atlanta, flow south
    through Georgia, and ultimately converge at Lake Seminole, just
    north of Florida, where the Apalachicola River begins and flows 106
    miles south into the Gulf of Mexico. In 2013, Florida, the down-
    stream State, sued Georgia, the upstream State, asking the Court to
    issue a decree equitably apportioning the Basin’s waters. The Court
    agreed to exercise its original jurisdiction and appointed a Special
    Master. The United States declined to waive its sovereign immunity
    from suit in the case. After conducting lengthy evidentiary proceed-
    ings, the Master submitted a Report recommending that the Court
    dismiss Florida’s complaint. That recommendation, the parties
    agree, turns on a single issue—namely, whether Florida met its ini-
    tial burden in respect to redressability. The Master concluded that
    Florida failed to make the requisite showing because it did not pre-
    sent clear and convincing evidence that its injuries could be redressed
    by a decree capping Georgia’s upstream water consumption if the de-
    cree does not also bind the Corps. Florida has filed exceptions to the
    Master’s Report.
    Held:
    1. The Special Master applied too strict a standard in concluding
    that Florida failed to meet its initial burden of demonstrating that
    the Court can eventually fashion an effective equitable decree.
    Pp. 10–18.
    (a) Where, as here, the Court is asked to resolve an interstate
    water dispute raising questions beyond the interpretation of specific
    language of an interstate compact, the doctrine of equitable appor-
    tionment applies. In this realm, several related but more specific
    2                          FLORIDA   v. GEORGIA
    Syllabus
    sets of principles guide the Court’s review. First, both Georgia and
    Florida possess “an equal right to make a reasonable use of the wa-
    ters of” the Flint River. United States v. Willow River Power Co., 
    324 U.S. 499
    , 505. Second, when confronted with competing claims to in-
    terstate water, the Court’s “effort always is to secure an equitable
    apportionment without quibbling over formulas.” New Jersey v. New
    York, 
    283 U.S. 336
    , 343. Third, in light of the sovereign status and
    “equal dignity” of States, a complaining State’s burden is “much
    greater” than the burden ordinarily shouldered by a private party
    seeking an injunction. Connecticut v. Massachusetts, 
    282 U.S. 660
    ,
    669. Among other things, it must demonstrate, by “ ‘clear and con-
    vincing evidence,’ ” that it has suffered a “ ‘threatened invasion of
    rights’ ” that is “ ‘of serious magnitude.’ ” Washington v. Oregon, 
    297 U.S. 517
    , 522. And to the extent the Court has addressed the “initial
    burden” a State bears in respect to redressability, the Court has said
    that “it should be clear that [the complaining] State has not merely
    some technical right, but also a right with a corresponding benefit” as
    a precondition to any equitable apportionment. Kansas v. Colorado,
    
    206 U.S. 46
    , 102, 109. An effort to shape a decree cannot be “a vain
    thing.” Foster v. Mansfield, C. & L. M. R. Co., 
    146 U.S. 88
    , 101. Fi-
    nally, because equitable apportionment is “ ‘flexible,’ ” not “formula-
    ic,” this Court will seek to “arrive at a ‘ “just and equitable” appor-
    tionment’ of an interstate stream” by “consider[ing] ‘all relevant
    factors,’ ” South Carolina v. North Carolina, 
    558 U.S. 256
    , 271, in-
    cluding, inter alia, “ ‘physical and climatic conditions, the consump-
    tive use of water in the several sections of the river, the character
    and rate of return flows, the extent of established uses, the availabil-
    ity of storage water, the practical effect of wasteful uses on down-
    stream areas, [and] the damage to upstream areas as compared to
    the benefits to downstream areas if a limitation is imposed on the
    former.’ ” Colorado v. New Mexico, 
    459 U.S. 176
    , 183. Because all
    relevant factors must be weighed, extensive and specific factual find-
    ings are essential for the Court to properly apply the doctrine of equi-
    table apportionment. See Nebraska v. Wyoming, 
    325 U.S. 589
    , 618.
    Pp. 10–15.
    (b) The Special Master applied too strict a standard when he de-
    termined that the Court would not be able to fashion an appropriate
    equitable decree. The Master referred to this as a “threshold” show-
    ing. But it is “threshold” only in the sense that the Master has not
    yet determined key remedy-related matters, including the approxi-
    mate amount of water that must flow into the Apalachicola River in
    order for Florida to receive a significant benefit from a cap on Geor-
    gia’s use of Flint River waters. Unless and until the Special Master
    Cite as: 585 U. S. ____ (2018)                       3
    Syllabus
    makes the findings of fact necessary to determine the nature and
    scope of likely harm caused by the absence of water and the amount
    of additional water necessary to ameliorate that harm significantly,
    the complaining State should not have to prove with specificity the
    details of an eventually workable decree by “clear and convincing” ev-
    idence. Rather, the complaining State should have to show that, ap-
    plying the principles of “flexibility” and “approximation,” it is likely to
    prove possible to fashion such a decree. To require “clear and con-
    vincing evidence” about the workability of a decree before the Court
    or a Special Master has a view about likely harms and likely amelio-
    ration is, at least in this case, to put the cart before the horse.
    Pp. 15–18.
    2. The Court reserves judgment as to the ultimate disposition of
    this case, addressing here only the narrow “threshold” question the
    Master addressed below—namely, whether Florida has shown that
    its “injur[ies can] effectively be redressed by limiting Georgia’s con-
    sumptive use of water from the Basin without a decree binding the
    Corps.” Report 30–31. Florida has made a legally sufficient showing
    as to the possibility of fashioning an effective remedial decree.
    Pp. 18–37.
    (a) The Report makes several key assumptions. First, the Mas-
    ter assumed Florida has suffered harm as a result of decreased water
    flow into the Apalachicola River. Second, the Master further as-
    sumed that Florida has shown that Georgia, contrary to equitable
    principles, has taken too much water from the Flint River. Third, the
    Master assumed that Georgia’s inequitable use of the water injured
    Florida. At this stage of the proceeding and in light of these assump-
    tions, Florida made a sufficient showing that the extra water that
    would result from its proposed consumption cap would both lead to
    increased streamflow in Florida’s Apalachicola River and significant-
    ly redress the economic and ecological harm that Florida has alleged.
    In addition, the United States has made clear that the Corps will co-
    operate in helping to implement any determinations and obligations
    the Court sets forth in a final decree in this case. While the Corps
    must take account of a variety of circumstances and statutory obliga-
    tions when it allocates water, it cannot now be said that an effort to
    shape a decree here will prove “a vain thing,” 
    Foster, supra, at 101
    ,
    since the record indicates that, if necessary and with the help of the
    United States, the Special Master, and the parties, the Court should
    be able to fashion a decree. Pp. 20–35.
    (b) Further findings, however, are needed on all of these eviden-
    tiary issues. Florida will be entitled to a decree only if it is shown
    that “the benefits of the [apportionment] substantially outweigh the
    harm that might result.” 
    Colorado, 459 U.S., at 187
    . On remand,
    4                        FLORIDA   v. GEORGIA
    Syllabus
    before fashioning a remedy, the Special Master must address several
    evidentiary questions that are assumed or found plausible here.
    Pp. 35–37.
    Case remanded.
    BREYER, J., delivered the opinion of the Court, in which ROBERTS,
    C. J., and KENNEDY, GINSBURG, and SOTOMAYOR, JJ., joined. THOMAS,
    J., filed a dissenting opinion, in which ALITO, KAGAN, and GORSUCH, JJ.,
    joined.
    Cite as: 585 U. S. ____ (2018)                              1
    Opinion of the Court
    NOTICE: This opinion is subject to formal revision before publication in the
    preliminary print of the United States Reports. Readers are requested to
    notify the Reporter of Decisions, Supreme Court of the United States, Wash­
    ington, D. C. 20543, of any typographical or other formal errors, in order
    that corrections may be made before the preliminary print goes to press.
    SUPREME COURT OF THE UNITED STATES
    _________________
    No. 142, Orig.
    _________________
    STATE OF FLORIDA, PLAINTIFF
    v. STATE OF GEORGIA
    ON EXCEPTIONS TO REPORT OF SPECIAL MASTER
    [June 27, 2018]
    JUSTICE BREYER delivered the opinion of the Court.
    This case concerns the proper apportionment of the
    water of an interstate river basin. Florida, a downstream
    State, brought this lawsuit against Georgia, an upstream
    State, claiming that Georgia has denied it an equitable
    share of the basin’s waters. We found that the dispute lies
    within our original jurisdiction, and we appointed a Spe­
    cial Master to take evidence and make recommendations.
    After lengthy evidentiary proceedings, the Special Mas­
    ter submitted a report in which he recommends that the
    Court deny Florida’s request for relief on the ground that
    “Florida has not proven by clear and convincing evidence
    that its injury can be redressed by an order equitably
    apportioning the waters of the Basin.” Report of Special
    Master 3. The case is before us on Florida’s exceptions to
    the Special Master’s Report.
    In light of our examination of the Report and relevant
    portions of the record, we remand the case to the Master
    for further findings and such further proceedings as the
    Master believes helpful.
    2                   FLORIDA v. GEORGIA
    Opinion of the Court
    I
    A
    This original action arises out of a dispute over the
    division of water from an interstate river basin known as
    the Apalachicola-Chattahoochee-Flint River Basin. The
    Basin drains an area of more than 20,000 square miles
    across the southeastern United States. Three interstate
    rivers form the heart of the Basin and are central to this
    case. They are the Chattahoochee River, the Flint River,
    and the Apalachicola River. It is easiest to think of these
    three rivers as forming the capital letter “Y,” with each
    branch starting at a different point in northeastern Geor­
    gia near Atlanta and the stem running through the Flor-
    ida panhandle and emptying into Apalachicola Bay in the
    Gulf of Mexico. See Appendix, infra.
    The Chattahoochee River is the western branch of this
    Y-shaped river system. It runs from the foothills of Geor­
    gia’s Blue Ridge Mountains, through most of Georgia,
    down to Lake Seminole, just north of Florida. The United
    States Army Corps of Engineers operates several dams
    and reservoirs along the Chattahoochee where it both
    stores water and controls the amount of water that flows
    downstream to Florida in accordance with the terms of its
    recently revised Master Water Control Manual (Master
    Manual). As we shall discuss in more detail, Part IV,
    infra, the Corps’ operations are important to the resolu­
    tion of this case.
    The Flint River, the eastern branch of the “Y,” runs from
    just south of Atlanta down to the same lake, namely, Lake
    Seminole. Unlike the Chattahoochee, there are no dams
    along the Flint River; it flows unimpeded through south­
    ern Georgia’s farmland, where the greatest share of the
    Basin’s water is consumed by agricultural irrigation.
    After water from the Flint and Chattahoochee Rivers
    mixes at Lake Seminole, the mixed water (now forming
    the stem of the Y) continues its southward journey. At the
    Cite as: 585 U. S. ____ (2018)           3
    Opinion of the Court
    southern end of Lake Seminole, it flows through the
    Woodruff Dam—a dam also controlled by the Corps. The
    mixed waters then change their name. They are called the
    Apalachicola River, and under that name they flow 106
    miles through the Florida Panhandle and finally empty
    into the Gulf of Mexico. There, the fresh water of the
    Apalachicola River mixes with the Gulf ’s saltwater, form­
    ing Apalachicola Bay, which the United Nations, the
    United States, and the State of Florida have all recognized
    as one of the Northern Hemisphere’s most productive
    estuaries. In total, the Apalachicola River accounts for
    35% of the fresh water that flows along Florida’s western
    coast. See Joint Exh. 168, p. 39.
    B
    Florida and Georgia have long disputed the apportion­
    ment of the Basin’s waters. Florida contends that Georgia
    is consuming more than its equitable share of Flint River
    water. It adds that, were Georgia to consume less water
    from the Flint River, more water would flow into Lake
    Seminole, pass through the Woodruff Dam and subse­
    quently flow down the Apalachicola River (the Y’s stem)
    and into Apalachicola Bay. The additional water that
    would result from a cap on Georgia’s consumption would,
    Florida argues, help (among other things) to recover and
    maintain its oyster industry, which collapsed following a
    drought in 2012. Georgia believes that it should not have
    to cut back on its Flint River water consumption because,
    in its view, it consumes no more than its equitable share.
    “This Court has recognized for more than a century its
    inherent authority, as part of the Constitution’s grant of
    original jurisdiction, to equitably apportion interstate
    streams between States.” Kansas v. Nebraska, 574 U. S.
    ___, ___ (2015) (slip op., at 7). But we have long noted our
    “preference” that States “settle their controversies by
    ‘mutual accommodation and agreement.’ ” Arizona v.
    4                   FLORIDA v. GEORGIA
    Opinion of the Court
    California, 
    373 U.S. 546
    , 564 (1963) (quoting Colorado v.
    Kansas, 
    320 U.S. 383
    , 392 (1943) (Kansas II)); see also 
    id., at 392
    (“[Interstate] controversies may appropriately be
    composed by negotiation and agreement, pursuant to the
    compact clause of the federal Constitution”); Kansas v.
    
    Nebraska, supra
    , at ___ (slip op., at 2–3) (describing codifi­
    cation of Republican River Compact); Montana v. Wyo-
    ming, 
    563 U.S. 368
    , 372 (2011) (interpreting Yellowstone
    River Compact); Kansas v. Colorado, 
    543 U.S. 86
    (2004)
    (resolving dispute over Arkansas River Compact).
    We recognize that Florida and Georgia (sometimes with
    the help of the Federal Government) have long tried to do
    so. But so far they have failed.
    In 1992, for example, the States signed a memorandum
    of agreement in which they “committed to a process for
    cooperative management and development” of the three-
    river Basin and agreed to “participate fully as equal part­
    ners” in a “comprehensive, basin-wide study” of its waters.
    Joint Exh. 004, at 1. Five years later, the States signed—
    and Congress approved—a compact, the Apalachicola­
    Chattahoochee-Flint River Basin Compact, in which they
    agreed:
    “to develop an allocation formula for equitably appor­
    tioning the surface waters of the ACF Basin among
    the states while protecting the water quality, ecology
    and biodiversity of the ACF.” 111 Stat. 2222–2223.
    But five years of negotiations under the Compact proved
    fruitless, and in 2003, the Compact expired.
    More than a decade later, in 2014, Congress again rec­
    ognized the need for an equitable apportionment of Basin
    waters. See Water Resources Reform and Development
    Act of 2014, Pub. L. 113–121, §1051(a), 128 Stat. 1259.
    But once again, despite drought, expanding city popula­
    tions, and a dramatic increase in acreage devoted to agri­
    cultural irrigation, no agreement has been reached. The
    Cite as: 585 U. S. ____ (2018)             5
    Opinion of the Court
    “last effort to reach an amicable resolution of this complex
    equitable apportionment proceeding” in 2017 was “unsuc­
    cessful.” Report 24. The States instead have come to this
    Court.
    II
    A
    In 2013, Florida, the downstream State, sought to sue
    Georgia, the upstream State, asking us to exercise our
    “original and exclusive jurisdiction” and issue a decree
    equitably apportioning the waters of the Basin. 
    28 U.S. C
    . §1251(a); see U. S. Const. Art. III, §2; see also this
    Court’s Rule 17. In its complaint, Florida alleged that
    Georgia’s consumption of Flint River water “reduce[s] the
    amount of water flowing to the Apalachicola River at all
    times,” and noted that “the effects are especially apparent
    during the low flow summer and fall periods.” Complaint
    9, ¶21; see also 
    id., at 17,
    ¶49 (complaining that the im­
    pact of Georgia’s water consumption “is significant, partic­
    ularly during dry periods”). In addition, Florida alleged
    that “[a]s Georgia’s upstream storage and consumption
    grows over time, low flow events will become more fre­
    quent and increase in severity, diminishing the likelihood
    that key species will survive and precluding any chance of
    recovery over the long term.” 
    Id., at 20,
    ¶59. To remedy
    these harms, Florida seeks a cap on Georgia’s consump­
    tion of water from the Flint River. 
    Id., at 21.
       Georgia filed a brief in opposition, arguing that Florida
    failed to allege an injury sufficient to warrant this Court’s
    exercise of original jurisdiction. See State of Georgia’s
    Opposition to Florida’s Motion for Leave to File a Com­
    plaint 31 (“Florida has not pleaded facts plausibly suggest­
    ing that it will be able to establish clear and convincing
    evidence that it suffers substantial injury as a result of
    Georgia’s consumption of water”). At our request, the
    United States filed a brief in which it told us that “Florida
    has pleaded an interstate water dispute of sufficient im­
    6                    FLORIDA v. GEORGIA
    Opinion of the Court
    portance to warrant this Court’s exercise of its original
    jurisdiction, and no other judicial forum is suitable for
    resolving the overall controversy.” Brief for United States
    as Amicus Curiae 12 (Sept. 18, 2014). But, the United
    States also warned that “[p]ractical considerations . . .
    weigh against the Court’s resolution of Florida’s claims
    before the Corps has completed its process of updating the
    Master Manual for the federal projects in the ACF Basin.”
    
    Ibid. It suggested that
    the Court could “grant Florida
    leave to file, but stay or provide for tailoring of any further
    proceedings until the Corps has issued the revised Master
    Manual” in March 2017, 
    id., at 13
    (which Florida has now
    done, see Brief for United States as Amicus Curiae 3, n. 1,
    10–12).
    We subsequently agreed to exercise our original juris­
    diction and appointed a Special Master “with authority to
    . . . direct subsequent proceedings,” “take such evidence as
    may be introduced and such as he may deem it necessary
    to call for,” and “submit Reports as he may deem appro­
    priate.” 574 U. S. ___ (2014).
    At the outset, the United States declined to waive its
    sovereign immunity from suit in this case. And shortly
    thereafter, Georgia asked the Special Master to dismiss
    the case on the grounds that the United States was a
    necessary party but could not be forced to intervene. See
    Fed. Rule Civ. Proc. 19(b). The Master concluded that the
    motion to dismiss Florida’s complaint should be denied.
    The Master reasoned that a decree binding the Corps
    might not prove necessary. Order on State of Georgia’s
    Motion To Dismiss 14–15 (June 19, 2015). Rather, the
    Master concluded that “the few facts before me at this
    stage of the proceeding support the conclusion that” a cap
    on Georgia’s Flint River water consumption could, at least
    in principle, redress Florida’s injuries either by increasing
    the amount of water that flows into Florida’s Apalachicola
    River or by “render[ing] periods of reduced flow releases
    Cite as: 585 U. S. ____ (2018)           7
    Opinion of the Court
    [into the Apalachicola River] fewer and further between
    because of the increased reservoir levels that would result
    from Georgia’s reduced consumption.” 
    Id., at 14,
    and n. 5.
    The Special Master pointed out that Florida would have to
    show that “a consumption cap is justified and will afford
    adequate relief.” 
    Id., at 13.
                                B
    The Master then held lengthy discovery and evidentiary
    proceedings. See Brief for Georgia 11; post, at 23 (opinion
    of THOMAS, J.) (“During their 18 months of discovery, the
    parties produced 7.2 million pages of documents”). Ulti­
    mately, the Master submitted a 70-page Report to this
    Court in February 2017. He recommended that the Court
    dismiss Florida’s complaint. In particular, despite the
    very large factual record amassed and “the extensive
    testimony bearing on numerous issues,” the Special Mas­
    ter stated:
    “I have concluded that there is a single, discrete issue
    that resolves this case: even assuming that Florida
    has sustained injury as a result of unreasonable up­
    stream water use by Georgia, can Florida’s injury ef­
    fectively be redressed by limiting Georgia’s consump­
    tive use of water from the Basin without a decree
    binding the [Army] Corps [of Engineers]? I conclude
    that Florida has not proven that its injury can be
    remedied without such a decree. The evidence does
    not provide sufficient certainty that an effective rem­
    edy is available without the presence of the Corps as a
    party in this case.” Report 30–31 (emphasis added).
    For present purposes, we note that Florida and Georgia
    agree that the Master’s recommendation “turned on a
    ‘single, discrete issue’—whether Florida had shown that a
    cap on Georgia’s consumption would redress its injury if
    the decree did not bind the Corps as well.” Florida Brief in
    8                   FLORIDA v. GEORGIA
    Opinion of the Court
    Support of Exceptions 23–24; see also Georgia’s Reply to
    Florida’s Exceptions 23 (“The Special Master reserved
    ruling on any issue other than effective redress”); Brief for
    United States as Amicus Curiae 19–20 (Aug. 7, 2017)
    (same).
    In reviewing this determination, we do not agree with
    the dissent’s view that the Master applied the “ordinary
    balance-of-harms test” that our equitable apportionment
    cases require. Post, at 14 (opinion of THOMAS, J.); see also
    Part III–A, infra, (describing equitable apportionment
    doctrine). As we shall explain, the dissent’s assertion that
    “the balance of harms cannot tip in Florida’s favor” is, at
    best, premature. Post, at 34–35. That judgment may
    eventually prove right or it may prove wrong. Here, as we
    just said, we consider only the “single” and “threshold”
    question of “redressability” upon which the Master rested
    his conclusion and which the parties have now argued
    here. In determining precisely what we now review, we
    rely upon (and do not go beyond) the Report’s specific and
    key statements, which include the following:
     “As a threshold matter, equitable apportionment is
    only available to a state that has suffered ‘real and
    substantial injury’ as a result of proposed or actual
    upstream water use” and “the injury must be re-
    dressable by the Court.” Report 24 (emphasis added).
     “Florida points to real harm and, at the very least,
    likely misuse of resources by Georgia. There is lit­
    tle question that Florida has suffered harm from
    decreased flows in the [Apalachicola] River,” in­
    cluding “an unprecedented collapse of its oyster
    fisheries in 2012.” 
    Id., at 31.
         “Much more could be said and would need to be said
    on these [and other] issues . . . .” 
    Id., at 34.
         “I need only address the narrow question of which
    Cite as: 585 U. S. ____ (2018)            9
    Opinion of the Court
    party bears the burden of proving injury and re-
    dressability.” 
    Id., at 28–29
    (emphasis added).
     “Florida bears the burden to prove that the pro­
    posed remedy will provide redress for Florida’s in­
    jury.” 
    Id., at 30.
        “Florida has not proven by clear and convincing evi­
    dence that any additional streamflow in the Flint
    River or in the Chattahoochee River would be re­
    leased from Jim Woodruff Dam into the Apala­
    chicola River at a time that would provide a mate-
    rial benefit to Florida (i.e., during dry periods),
    thereby alleviating Florida’s injury.” 
    Id., at 47
          (emphasis added).
     “Florida has provided no evidence that a decree in
    this case could provide an effective remedy during
    normal (i.e., non-drought) periods.” 
    Id., at 68.
        “[T]he Corps can likely offset increased streamflow
    in the Flint River by storing additional water in its
    reservoirs along the Chattahoochee River during
    dry periods [and so] . . . [t]here is no guarantee that
    the Corps will exercise its discretion to release or
    hold back water at any particular time.” 
    Id., at 69
          (emphasis added).
     “[W]ithout the Corps as a party, the Court cannot
    order the Corps to take any particular action.” 
    Id., at 69
    –70.
    C
    Florida has filed exceptions to the Special Master’s
    Report. Florida first challenges the legal standard the
    Master applied in resolving what the Master called the
    “threshold” question whether Florida had “proven. . . that
    its injury can be redressed by an order equitably appor­
    tioning the waters of the Basin.” 
    Id., at 24,
    3. The Master
    10                   FLORIDA v. GEORGIA
    Opinion of the Court
    wrote that Florida must meet a “clear and convincing
    evidence” evidentiary burden. 
    Id., at 3.
    Second, Florida
    argues that, in any event, its showing in respect to re­
    dressability was sufficient. We consider each of these
    exceptions in turn.
    III
    A
    We note at the outset that our role in resolving disputes
    between sovereign States under our original jurisdiction
    “significantly differs from the one the Court undertakes ‘in
    suits between private parties.” Kansas v. Nebraska, 574
    U. S., at ___ (slip op., at 6) (internal quotation marks and
    alterations omitted). “In this singular sphere,” we have
    observed, “ ‘the court may regulate and mould the process
    it uses in such a manner as in its judgment will best pro­
    mote the purposes of justice.’ ” Id., at ___ (slip op., at 6–7)
    (quoting Kentucky v. Dennison, 
    24 How. 66
    , 98 (1861)).
    We must approach interstate disputes “in the untechnical
    spirit proper for dealing with a quasi-international contro­
    versy, remembering that there is no municipal code gov­
    erning the matter, and that this court may be called on to
    adjust differences that cannot be dealt with by Congress or
    disposed of by the legislature of either State alone.” Vir-
    ginia v. West Virginia, 
    220 U.S. 1
    , 27 (1911) (Holmes, J.).
    Where, as here, the Court is asked to resolve an inter­
    state water dispute raising questions beyond the interpre­
    tation of specific language of an interstate compact, the
    doctrine of equitable apportionment governs our inquiry.
    See Colorado v. New Mexico, 
    459 U.S. 176
    , 183 (1982)
    (Colorado I); Virginia v. Maryland, 
    540 U.S. 56
    , 74, n. 9
    (2003) (“Federal common law governs interstate bodies of
    water, ensuring that the water is equitably apportioned
    between the States and that neither State harms the
    other’s interest in the river”). In this realm, we have kept
    in mind several related but more specific sets of principles.
    Cite as: 585 U. S. ____ (2018)           11
    Opinion of the Court
    First, as the Special Master pointed out, “the relevant
    guiding principle in this case” is a simple one. Report 26–
    27. Given the laws of the States, both Georgia and Florida
    possess “ ‘an equal right to make a reasonable use of the
    waters of the stream’ ”—which, in this case, is the Flint
    River. 
    Id., at 26
    (quoting United States v. Willow River
    Power Co., 
    324 U.S. 499
    , 505 (1945)); see also Colorado 
    I supra, at 184
    (“Our prior cases clearly establish that
    equitable apportionment will only protect those rights to
    water that are ‘reasonably required and applied.’ . . .
    [W]asteful or inefficient uses will not be protected (quoting
    Wyoming v. Colorado, 
    259 U.S. 419
    , 484 (1922))); Idaho ex
    rel. Evans v. Oregon, 
    462 U.S. 1017
    , 1025 (1983) (Idaho
    II ) (“States have an affirmative duty under the doctrine of
    equitable apportionment to take reasonable steps to con­
    serve and even to augment the natural resources within
    their borders for the benefit of other States”); Nebraska v.
    Wyoming, 
    325 U.S. 589
    , 618 (1945); Kansas 
    II, 320 U.S., at 394
    ; Washington v. Oregon, 
    297 U.S. 517
    , 522, 527–528
    (1936); New Jersey v. New York, 
    283 U.S. 336
    , 342–343
    (1931); North Dakota v. Minnesota, 
    263 U.S. 365
    , 372
    (1923) (reaffirming that an upstream State may not “bur­
    den his lower neighbor with more than is reasonable”);
    Kansas v. Colorado, 
    206 U.S. 46
    , 102 (1907) (Kansas I);
    Tyler v. Wilkinson, 
    24 F. Cas. 472
    , 474 (No. 14,312) (CC RI
    1827) (Story, J.) (setting forth the principle of “reasonable
    use”).
    Second, our prior decisions emphasize that, when we are
    confronted with competing claims to interstate water, the
    Court’s “effort always is to secure an equitable apportion­
    ment without quibbling over formulas.” New Jersey v.
    New 
    York, 283 U.S., at 342
    –343 (Holmes, J.). Where
    “[b]oth States have real and substantial interests in the
    River,” those interests “must be reconciled as best they
    may be.”       
    Id., at 342–343.
         We have added that
    “[u]ncertainties about the future . . . do not provide a basis
    12                   FLORIDA v. GEORGIA
    Opinion of the Court
    for declining to fashion a decree.” Idaho 
    II, 462 U.S., at 1026
    ; see also 
    ibid. (“Reliance on reasonable
    predictions of
    future conditions is necessary”); Colorado v. New Mexico,
    
    467 U.S. 310
    , 322 (1984) (Colorado II ) (requiring “abso­
    lute precision in forecasts . . . would be unrealistic”); North
    Dakota v. 
    Minnesota, supra, at 386
    (emphasizing the need
    to “draw inferences as to the probabilities”); Kansas 
    I, supra, at 97
    –98.
    Third, in light of the sovereign status and “equal dignity”
    of States, a complaining State must bear a burden that is
    “much greater” than the burden ordinarily shouldered by
    a private party seeking an injunction. Connecticut v.
    Massachusetts, 
    282 U.S. 660
    , 669 (1931); see Kansas 
    II, supra, at 392
    (“The reason for judicial caution in adjudi­
    cating the relative rights of States in such cases is that,
    while we have jurisdiction of such disputes, they involve
    the interests of quasi-sovereigns, present complicated and
    delicate questions, and, due to the possibility of future
    change of conditions, necessitate expert administration
    rather than judicial imposition of a hard and fast rule”
    (footnote omitted)). In particular, “ ‘[b]efore this court can
    be moved to exercise its extraordinary power under the
    Constitution to control the conduct of one State at the suit
    of another,’ ” the complaining State must demonstrate that
    it has suffered a “ ‘threatened invasion of rights’ ” that is
    “ ‘of serious magnitude.’ ” Washington v. 
    Oregon, supra, at 524
    (quoting New York v. New Jersey, 
    256 U.S. 296
    , 309
    (1921)). The State must make that showing by “ ‘clear and
    convincing evidence.’ ” Washington v. 
    Oregon, supra, at 522
    (quoting New York v. New 
    Jersey, supra, at 309
    ); see
    also Idaho 
    II, supra, at 1027
    (“A State seeking equitable
    apportionment under our original jurisdiction must prove
    by clear and convincing evidence some real and substan­
    tial injury or damage”); Colorado 
    I, supra, at 187
    –188,
    n. 13 (“[A] state seeking to prevent or enjoin [an upstream]
    diversion by another State” must “bear the initial burden
    Cite as: 585 U. S. ____ (2018)           13
    Opinion of the Court
    of showing that a diversion by [the upstream State] will
    cause substantial injury to [the downstream State’s] inter­
    ests” (emphasis added)).
    In addition, to the extent the Court has addressed the
    “initial burden” a State bears in respect to redressability,
    our prior decisions make clear that, as a general matter,
    “[t]o constitute a justiciable controversy, it must appear
    that the complaining State has suffered a wrong through
    the action of the other State, furnishing a ground for
    judicial redress, or is asserting a right against the other
    State which is susceptible of judicial enforcement accord­
    ing to the accepted principles of the common law or equity
    systems of jurisprudence.” Massachusetts v. Missouri, 
    308 U.S. 1
    , 15 (1939)); see also Wyoming v. Oklahoma, 
    502 U.S. 437
    , 447, 452 (1992) (same); Maryland v. Louisiana,
    
    451 U.S. 725
    , 735–736 (1981). More specifically, we have
    said that “it should be clear that [the complaining] State
    has not merely some technical right, but also a right with
    a corresponding benefit” as a precondition to any equitable
    apportionment. Kansas 
    I, supra, at 109
    . An effort to
    shape a decree cannot be “a vain thing.” Foster v. Mans-
    field, C. & L. M. R. Co., 
    146 U.S. 88
    , 101 (1892). A State
    “will not be granted [relief] against something merely
    feared as liable to occur at some indefinite time in the
    future,” Connecticut v. 
    Massachusetts, supra, at 674
    , or
    when there is “no other or better purpose [at stake] than
    to vindicate a barren right.” Washington v. 
    Oregon, supra, at 523
    ; cf. Idaho 
    II, supra, at 1026
    (assessing whether “the
    formulation of a workable decree is impossible”).
    Fourth, in an interstate water matter, where a com­
    plaining State meets its “initial burden of showing ‘real or
    substantial injury,’ ” Colorado 
    II, supra, at 317
    (quoting
    Colorado 
    I, 459 U.S., at 188
    , n. 13), this Court, recalling
    that equitable apportionment is “ ‘flexible,’ ” not “formu-
    laic,” will seek to “arrive at a ‘ “just and equitable” appor­
    tionment’ of an interstate stream” by “consider[ing] ‘all
    14                   FLORIDA v. GEORGIA
    Opinion of the Court
    relevant factors.’ ” South Carolina v. North Carolina, 
    558 U.S. 256
    , 271 (2010) (quoting Colorado 
    I, 459 U.S., at 183
    ); see also 
    id., at 190
    (“Whether [relief] should be per­
    mitted will turn on an examination of all factors relevant
    to a just apportionment”); Kansas 
    II, 320 U.S., at 393
    –394
    (“[I]n determining whether one State is using, or threaten­
    ing to use, more than its equitable share of the benefits of
    a stream, all the factors which create equities in favor of
    one State or the other must be weighed”) (emphasis
    added). These factors include (but are not limited to):
    “physical and climatic conditions, the consumptive use
    of water in the several sections of the river, the char­
    acter and rate of return flows, the extent of estab­
    lished uses, the availability of storage water, the prac­
    tical effect of wasteful uses on downstream areas,
    [and] the damage to upstream areas as compared to
    the benefits to downstream areas if a limitation is im­
    posed on the former.” Nebraska v. 
    Wyoming, 325 U.S., at 618
    .
    Because “all the factors which create equities in favor of
    one State or the other must be weighed,” Kansas 
    II, supra, at 394
    (emphasis added), extensive and “specific factual
    findings” are essential for the Court to properly apply the
    doctrine of equitable apportionment. Colorado 
    I, supra, at 189
    –190 (emphasis added). And given the complexity of
    many water-division cases, the need to secure equitable
    solutions, the need to respect the sovereign status of the
    States, and the importance of finding flexible solutions to
    multi-factor problems, we typically appoint a Special
    Master and benefit from detailed factual findings.
    Without the full range of factual findings, we have said,
    the Court may lack an adequate basis on which to make
    “the delicate adjustment of interests” that the law re­
    quires. Nebraska v. 
    Wyoming, supra, at 618
    ; Washington
    v. 
    Oregon, 297 U.S., at 519
    , 523–524 (emphasizing that
    Cite as: 585 U. S. ____ (2018)           15
    Opinion of the Court
    “the Master’s Report finds the facts fully”); see also Colo-
    rado 
    I, supra, at 183
    , 189–190 (remanding “with instruc­
    tions to the Special Master to make further findings of
    fact”); Colorado 
    II, 467 U.S., at 312
    –315 (explaining that
    because “the Master’s report [was] unclear,” the Court
    remanded to the Special Master “for additional factual
    findings on five specific issues” even after “a lengthy trial
    at which both States presented extensive evidence” in
    order “to assist this Court in balancing the benefit and
    harm”); Texas v. New Mexico, 
    462 U.S. 554
    , 575–576, and
    n. 21 (1983) (“[W]e return this case to the Special Master
    for determination of the unresolved issues framed in his
    pretrial order”); 3 A. Kelley, Water and Water Rights
    §45.02(c), p. 45–14 (3d ed. 2018) (“If the factual findings in
    the report are insufficient for the Court to decide whether
    the master correctly applied the doctrine of equitable
    apportionment, the Court may refer the case back to the
    master for additional findings”).
    B
    Applying the principles just described, we conclude that
    the Special Master applied too strict a standard when he
    determined that the Court would not be able to fashion an
    appropriate equitable decree. See Report 3 (“Florida has
    not proven by clear and convincing evidence that its injury
    can be redressed by an order equitably apportioning the
    waters of the Basin”); see also 
    id., at 31
    (“The evidence
    does not provide sufficient certainty that an effective
    remedy is available without the presence of the Corps as a
    party in this case”).
    The Special Master referred to the relevant showing
    that Florida must make in this respect as a “threshold”
    showing. Report 24. We agree that the matter is “thresh­
    old” in one particular sense—namely, the sense that the
    Master has not yet determined several key remedy-related
    matters, including the approximate amount of water that
    16                  FLORIDA v. GEORGIA
    Opinion of the Court
    must flow into the Apalachicola River in order for Florida
    to receive a significant benefit from a cap on Georgia’s use
    of Flint River waters. See infra, at 28. The Master also
    wrote that Florida had failed to show “with sufficient
    certainty that the Corps must (or will choose to) operate
    its projects so as to permit all additional flows in the Flint
    River” or “the entire marginal increase in streamflow” to
    reach Florida “without any substantial delay.” 
    Id., at 48
    (emphasis added); see also 
    id., at 24,
    70 (similar). He
    added that there “is no guarantee” that the Corps will
    exercise its relevant discretion. 
    Id., at 69
    (emphasis added).
    And he said that Florida must show the existence of a
    workable remedy by “clear and convincing evidence.” 
    Id., at 3;
    see also, e.g., 
    id., at 28–29,
    47, 51, 69–70.
    We believe the Master’s standard, as indicated by these
    statements, is too strict. In our view, unless and until the
    Special Master makes the findings of fact necessary to
    determine the nature and scope of likely harm caused by
    the absence of water and the amount of additional water
    necessary to ameliorate that harm significantly, the com­
    plaining State should not have to prove with specificity
    the details of an eventually workable decree by “clear and
    convincing” evidence.         Rather, the complaining State
    should have to show that, applying the principles of “flexi­
    bility” and “approximation” we discussed above, it is likely
    to prove possible to fashion such a decree. 
    See supra, at 12
    .
    To require more definite proof at the outset may well (at
    least on some occasions) make little sense. Suppose, for
    example, downstream State A claims that upstream State
    B wastes at least 10,000 cubic feet per second (cfs) of
    water. And suppose further that no decree could enforce a
    10,000 cfs consumption cap but that it may well prove
    possible to enforce a lesser requirement. If so, we would
    have to know at least approximately how much water will
    significantly ameliorate State A’s water problem before we
    Cite as: 585 U. S. ____ (2018)           17
    Opinion of the Court
    could know whether it is possible to shape a workable
    decree. And the workability of decrees themselves, ap­
    proximate as they may be, may depend upon more precise
    findings in respect to the nature and scope of the range of
    likely harms and likely benefits that a Special Master
    finds are actually likely to exist. To require “clear and
    convincing evidence” about the workability of a decree
    before the Court or a Special Master has a view about
    likely harms and likely amelioration is, at least in this
    case, to put the cart before the horse. And that, we fear, is
    what the Master’s statements, with their apparent refer­
    ences to a “clear and convincing” evidence standard in
    respect to “redressability” (where that refers to the availa­
    bility of an eventual decree) have done here. Cf. post, at
    17–19.
    That is also why our cases, while referring to the use of
    a “clear and convincing” evidentiary standard in respect to
    an initial showing of “invasion of rights” and “substantial
    injury,” have never referred to that standard in respect to
    a showing of “remedy” or “redressability.” See Nebraska v.
    Wyoming, 
    515 U.S. 1
    , 8 (1995) (repeating that as a
    threshold matter, a “ ‘threatened invasion of rights must
    be of a serious magnitude and it must be established by
    clear and convincing evidence’ ” without addressing the
    required initial burden in respect to remedy (quoting New
    York v. New 
    Jersey, 256 U.S., at 309
    )); Colorado 
    II, supra, at 317
    (describing the “initial burden” a State bears to
    show “ ‘real or substantial injury’ ” (quoting Colorado 
    I, 459 U.S., at 187
    –188, n. 13)); Idaho 
    II, 462 U.S., at 1027
    ;
    Colorado 
    I, supra, at 187
    –188, and n. 13 (“[A] State seek­
    ing to prevent or enjoin [an upstream] diversion by another
    State” must “bear the initial burden of showing that a
    diversion by [the upstream State] will cause substantial
    injury to [the downstream State’s] interests” (emphasis
    added)); Washington v. 
    Oregon, 297 U.S., at 522
    ; Connect-
    icut v. 
    Massachusetts, 282 U.S., at 672
    ; New Jersey v. New
    18                  FLORIDA v. GEORGIA
    Opinion of the Court
    
    York, 283 U.S., at 344
    –345; Kansas 
    II, 320 U.S., at 393
    –
    394. The dissent does not dispute this. See post, at 12.
    As 
    discussed, supra, at 12
    –13, our prior decisions have
    said that the “right” a complaining State asserts must be
    more than “merely some technical right” and must be “a
    right with a corresponding benefit,” Kansas 
    I, 206 U.S., at 109
    (emphasis added)—an effort to shape an equitable
    apportionment decree cannot be “a vain thing.” 
    Foster, 146 U.S., at 101
    ; see also Idaho 
    II, supra, at 1026
    (as­
    sessing whether “the formulation of a workable decree is
    impossible”); Washington v. 
    Oregon, supra, at 523
    . But
    these statements apply to the general availability of judi­
    cial relief—not to the details of a final decree or to the
    workability of a decree that will depend on those details.
    Cf. Idaho ex rel. Evans v. Oregon 
    444 U.S. 380
    , 392 (1980)
    (Idaho I ) (explaining that the question whether a State’s
    proposed remedy will have an “appreciable effect” is a
    question that “goes to the merits” of the equitable appor­
    tionment inquiry). And, of course, to insist upon the use of
    such a strict standard, in respect to an eventual decree,
    runs directly contrary to the statements in, and holdings
    of, cases to which we have referred when discussing the
    need for “approximation” and “flexibility.” 
    See supra, at 13
    –14.
    IV
    We next address Florida’s exceptions to the Master’s
    evidentiary determinations. In doing so, we recognize that
    the record in this case is long. It addresses a number of
    highly technical matters on a range of subjects—from
    biology to hydrology to the workings of the Corps’ newly
    revised Master Manual governing the organization’s com­
    plex operations in the Basin. Insofar as the Special Mas­
    ter made findings of fact, those findings “deserve respect
    and a tacit presumption of correctness.” Colorado 
    II, 467 U.S., at 317
    . But at the end of the day, “the ultimate
    Cite as: 585 U. S. ____ (2018)           19
    Opinion of the Court
    responsibility for deciding what are correct findings of fact
    remains with us.” 
    Ibid. We have therefore
    read those
    portions of the record to which the parties, amici, or the
    Master refer, along with several other portions that we
    have found potentially relevant. Our “independent exam­
    ination of the record,” Kansas v. Missouri, 
    322 U.S. 213
    ,
    232 (1944), leads us to conclude that, at this stage, Florida
    has met its “initial burden” in respect to remedy. But, we
    also believe that a remand is necessary to conduct the
    equitable-balancing inquiry. Cf. Colorado 
    I, supra, at 183
    –190.
    We reserve judgment as to the ultimate disposition of
    this case, addressing here only the narrow “threshold”
    question the Master addressed below—namely, whether
    Florida has shown that its “injur[ies can] effectively be
    redressed by limiting Georgia’s consumptive use of water
    from the Basin without a decree binding the Corps.”
    Report 30–31. This dispositive threshold question leads
    us, in turn, to focus upon five subsidiary questions:
    First, has Florida suffered harm as a result of decreased
    water flow into the Apalachicola River? (The Special
    Master assumed “yes.”)
    Second, has Florida shown that Georgia, contrary to
    equitable principles, has taken too much water from the
    Flint River (the eastern branch of the Y-shaped river
    system)? (Again, the Special Master assumed “yes.”)
    Third, if so, has Georgia’s inequitable use of Basin
    waters injured Florida? (The Special Master assumed
    “yes.”)
    Fourth, if so, would an equity-based cap on Georgia’s
    use of the Flint River lead to a significant increase in
    streamflow from the Flint River into Florida’s Apalachicola
    River (the stem of the Y)? (This is the basic question
    before us.)
    Fifth, if so, would the amount of extra water that reaches
    the Apalachicola River significantly redress the economic
    20                  FLORIDA v. GEORGIA
    Opinion of the Court
    and ecological harm that Florida has suffered? (This
    question is mostly for remand.)
    As our parentheticals suggest, the Special Master as­
    sumed that the answer to the first three questions was
    “yes.” The fourth question is the question before us now.
    And the fifth question is partly for us now and partly for
    the Master to answer on remand.
    A
    The Report indicates that the Special Master assumed
    the answer to the first question is “yes.” The Report says
    that the Special Master reached his conclusion on the
    “single, discrete issue that resolves this case” by “assum-
    ing that Florida has sustained injury.” 
    Id., at 30
    (empha­
    sis added); see also 
    id., at 2
    (repeating Georgia’s argument
    that “without an order binding the Corps, Florida will not
    be assured any relief—assuming it has suffered any injury
    at all—by a decree entered in this proceeding because the
    Corps has the ability to impound water in various reser­
    voirs that it maintains in the Basin” (emphasis added));
    
    id., at 65
    (“Even if there were evidence of harm from other
    than low-flow conditions . . . ”).
    At the same time, the Report states that “Florida points
    to real harm.” 
    Id., at 31.
    And the Master specified that
    there is “little question that Florida has suffered harm
    from decreased flows in the [Apalachicola] River.” 
    Id., at 31
    (emphasis added). That harm—caused (at least in
    part) by increased salinity—includes “an unprecedented
    collapse of [Florida’s] oyster fisheries in 2012.” Ibid.; see
    
    id., at 32
    (stating that “the evidence presented tends to
    show that increased salinity . . . led to the collapse” of
    Apalachicola Bay’s oysters and “greatly harmed the oys­
    termen of the Apalachicola Region, threatening their
    longterm sustainability”). Cf. New Jersey v. New 
    York, 283 U.S., at 343
    , 345 (finding redressable harm to oysters
    caused by diminished water flow and increased salinity).
    Cite as: 585 U. S. ____ (2018)          21
    Opinion of the Court
    The harms of reduced streamflow may extend to other
    species in the Apalachicola Region, including in the river
    and its floodplain, which, as the Master noted, “is home to
    the highest species density of amphibians and reptiles in
    all of North America, and supports hundreds of endan­
    gered or threatened animal and plant species,” including
    three “endangered” or “threatened” mussel species, the
    “[t]hreatened Gulf sturgeon,” and the largest stand of
    Tupelo trees—of Tupelo Honey fame—in the world. Re­
    port 7–8; see also Joint Exh. 168, at 193, 195–196.
    B
    The Master also appears to have assumed the answer to
    the second question is “yes.” The Report reached its key
    conclusion that Florida’s (assumed) injuries cannot “effec­
    tively be redressed” by “assuming that Florida has sus­
    tained injury as a result of unreasonable upstream water
    use by Georgia.” Report 30 (emphasis added). But, at the
    same time, the Master acknowledged that “Florida points
    to real harm and, at the very least, likely misuse of re­
    sources by Georgia.” 
    Id., at 31
    (emphasis added). And the
    Report “provide[s] the Court a brief descriptive back­
    ground regarding . . . the unreasonableness of Georgia’s
    consumptive water use.” Ibid.; see, e.g., 
    id., at 32
    (“Geor­
    gia’s upstream agricultural water use has been—and
    continues to be—largely unrestrained”); 
    id., at 33
    (“De­
    spite early warnings of oncoming drought, Georgi[a] . . .
    chose not to declare a drought in 2011—apparently hoping
    for the best, and clearly not wishing to incur the cost of
    preventative action”); 
    id., at 34
    (“Georgia’s position—
    practically, politically, and legally—can be summarized as
    follows: Georgia’s agricultural water use should be subject
    to no limitations, regardless of the long-term consequences
    for the Basin”).
    22                  FLORIDA v. GEORGIA
    Opinion of the Court
    C
    In respect to the third question, the Master again as­
    sumed the answer “yes.” In particular, the Report “as­
    sume[s]” that “Florida has sustained injury as a result of
    unreasonable upstream water use by Georgia.” 
    Id., at 30
    (emphasis added). And as relevant to each of the first
    three questions, the Master added that “[m]uch more
    could be said and would need to be said about” Florida’s
    injuries, the reasonableness of Georgia’s water consump­
    tion, and “other issues, such as causation,” if the case
    proceeds. 
    Id., at 34.
    As we have explained, our prior
    equitable apportionment decisions make clear that “all
    factors which create equities in favor of one State or the
    other must be weighed.” Kansas 
    II, 320 U.S., at 393
    –394
    (emphasis added). Thus, a remand is necessary to consid­
    er each of the relevant factors, including those upon which
    the dissent focuses. See infra, at 27; Nebraska v. Wyo-
    
    ming, 325 U.S., at 618
    ; cf. Colorado 
    II, 467 U.S., at 323
    –324.
    D
    We now turn to the fourth question, the basic question
    before us. Would an equity-based cap on Georgia’s use of
    the Flint River lead to a significant increase in streamflow
    from the Flint River into Florida’s Apalachicola River (the
    stem of the Y)? The answer depends upon (1) the amount
    of extra water that would flow into Lake Seminole as a
    result of a cap on Georgia’s Flint River water consump­
    tion; and (2) the amount of water that could actually flow
    through the Corps-controlled Woodruff Dam at Lake
    Seminole’s southern end and into Florida’s Apalachicola
    River.
    1
    The record shows that Florida’s proposed cap on Geor­
    gia’s water consumption could result in the release of
    Cite as: 585 U. S. ____ (2018)            23
    Opinion of the Court
    considerable extra water into Lake Seminole. Florida’s
    expert, Dr. David Sunding, testified that the cap would
    limit the average amount of water that Georgia could use
    annually and also reduce the amount of water that Geor­
    gia could use during drought years, which could “materially
    reduce [Georgia’s] depletions of river flows . . . by 1,500 to
    over 2,000 cubic feet per second (cfs) in peak summer
    months of drought years.” Updated Pre-Filed Direct
    Testimony (PFDT) of Sunding ¶8; see also 
    id., ¶¶88–90. Dr.
    Sunding added that it would cost Georgia roughly $35
    million annually (less than 0.2% of Georgia’s annual bud-
    get) to reduce streamflow depletions by 2,000 cfs. 
    Id., ¶113, Table
    4. Georgia’s expert, Dr. Robert Stavins, disputed
    these conclusions. See Direct Testimony of Stavins ¶¶4,
    90, 136; see also Brief for Georgia 18. The Master did not
    make specific findings of fact regarding this aspect of
    Florida’s proposed remedy. Rather than expressly making
    any findings, the Master apparently “accept[ed] Florida’s
    estimates of the increased streamflow that would result
    from a consumption cap.” Report 67, n. 43. At this stage,
    we shall do the same.
    And as we shall later discuss, the record suggests that
    an increase in streamflow of 1,500 to 2,000 cfs is reason-
    ably likely to benefit Florida significantly. See infra, at 39–
    40 (citing record evidence of benefits); see also Updated
    PFDT of J. David Allan ¶¶3d, 26, 67 (Allan) (discussing
    ecological benefits of increasing streamflow by 300 to 500
    cfs); 10 Tr. 2629:7–15 (Kondolf) (detailing benefits of
    increasing streamflow into the Apalachicola River from
    5,000 to 7,000 cfs); 3 
    id., at 591:6–593:4,
    596:17–598:1
    (Allan).
    2
    The key question, however, is whether the 1,500 to
    2,000 cfs of extra water that will flow into Lake Seminole
    from the Flint River as a result of a cap on Georgia’s water
    24                  FLORIDA v. GEORGIA
    Opinion of the Court
    consumption will flow beyond Lake Seminole, through the
    Woodruff Dam, and into the Apalachicola River at the
    relevant times. That is where the Army Corps of Engi­
    neers enters the picture. And it is where Florida disagrees
    with the Special Master and with Georgia. The Special
    Master and Georgia believe that—at any relevant time—
    the Corps might “offset” any extra Flint River water that
    flows into Lake Seminole by simultaneously reducing the
    amount of water that flows into that lake from the Chat­
    tahoochee River. See Report 48–53. Thus, if the 1,500 to
    2,000 cfs of extra water that would reach Lake Seminole
    from the Flint as a result of Florida’s proposed consump­
    tion cap, the question is whether and to what extent the
    Corps will “offset” that extra streamflow by releasing
    1,500 to 2,000 cfs less water into Lake Seminole from its
    upstream Chattahoochee reservoirs.
    Of course, the Corps might, under certain circumstances,
    be authorized to “offset” extra streamflow from the
    Flint River. As the Special Master wrote, “[t]here is no
    guarantee that the Corps will exercise its discretion to
    release or hold back water at a particular time.” 
    Id., at 69
    .
    But as the United States has explained, increased stream-
    flow into Lake Seminole (that is, increased Basin Inflow)
    “would generally benefit the ACF system by delaying the
    onset of drought operations, by allowing the Corps to meet
    the 5000 cfs minimum flow longer during extended
    drought, and by quickening the resumption of normal
    operations after drought.” Brief for United States as
    Amicus Curiae 28 (Aug. 7, 2017). And our reading of the
    record convinces us it is highly unlikely that the Corps
    will always reduce the flow in this way; it leads us to
    believe that, acting in accordance with the its own revised
    Master Manual, the Corps is likely to permit, and in some
    cases may be required to ensure that, material amounts of
    additional Flint water to flow through the Woodruff Dam
    and into the Apalachicola River. At the very least, we
    Cite as: 585 U. S. ____ (2018)         25
    Opinion of the Court
    believe that more proceedings are necessary to reach a
    definitive determination.
    As an initial matter, the Master Manual makes clear
    that the amount of water the Corps will release turns in
    part on the amount of water stored in the Corps’ Chatta­
    hoochee reservoirs. See U. S. Army Corps of Engineers,
    Master Manual, Apalachicola-Chattahoochee-Flint River
    Basin, Florida and Georgia, App. A, pp. 7–4 to 7–5, 7–7.
    More specifically, the amount of water storage in those
    reservoirs dictates whether the Corps is conducting one of
    two possible types of “operations”—namely, “drought
    operations” or “nondrought operations.” These are tech­
    nical terms. See 
    id., at 7–14
    to 7–16. The term “drought
    operations” need not correspond to dry periods, nor need
    the term “nondrought operations” refer to wet periods.
    Rather their applicability depends in part upon the
    amount of water that is stored behind the Corps’ Chatta­
    hoochee dams. As the United States explained, “[t]he
    term ‘drought operations’ refers to more conservative
    operations that [the Corps conducts, which] are intended
    to enable the Corps to preserve water and operate its
    reservoir projects more effectively as drought conditions
    arise.” Brief for United States as Amicus Curiae 9 (Aug.
    7, 2017). We therefore must clearly distinguish what the
    record tells us about the amount of extra water that could
    flow into Florida as a result of a consumption cap during
    each of these two distinct types of Corps operations.
    a
    Nondrought Operations
    When the Corps is conducting “nondrought operations,”
    the Master Manual requires the Corps to release into
    Florida all or some of any extra water that flows from the
    Flint River into Lake Seminole, where it will then flow
    through the Woodruff Dam. See App. to Brief for United
    States as Amicus Curiae 2a (Aug. 7, 2017) (detailing Corps
    operational protocol). As the United States has explained,
    26                  FLORIDA v. GEORGIA
    Opinion of the Court
    when the total streamflow into Lake Seminole is between
    5,000 and 10,000 cfs during “nondrought operations,” the
    following facts are true:
    “[A]ny additional basin inflow . . . would generally be
    passed straight through to Florida. If, for example,
    the conservation measures advocated by Florida as
    part of a consumption cap actually resulted in an in­
    creased flow in the Flint River of 2,000 cfs, see Pre-
    Filed Direct Testimony of David Sunding, Ph. D. at
    44, Table 4, then flows into Florida would also in­
    crease by roughly that amount.” United States Post-
    Trial Brief 12–13 (Dec. 15, 2016); see also Brief for
    United States as Amicus Curiae 18 (Aug. 7, 2017) (re­
    affirming that under these circumstances “flows in the
    Apalachicola would increase by the amount of in­
    creased Flint River flows” including during summer
    months).
    As far as we can tell, under the Corps’ current opera­
    tional protocol, the Corps may remain in “nondrought
    operations” even during the driest summer months of the
    driest years. For example, in 2007 the Corps conducted
    “nondrought operations” not only during late autumn,
    winter, and spring months, but also during the hottest
    summer and early autumn months “when streamflow is at
    its lowest.” See Direct Testimony of Phillip Bedient ¶¶48–
    53 (stating that “[i]f 2007’s Basin Inflow were repeated
    today and Drought Operations were not triggered,” the
    Corps would have had 92 days of “nondrought operations,”
    including 19 days “during summer and fall months, when
    streamflow was at its lowest” on which 100% of extra
    water resulting from a consumption cap would reach
    Florida). We note that these 19 days fell during a period
    of severe drought in which no extra water (let alone 2,000
    cfs of extra water) was flowing into Lake Seminole. And,
    unsurprisingly, the same trend appears to be true in dry
    Cite as: 585 U. S. ____ (2018)            27
    Opinion of the Court
    summer months of other years: all or some of the extra
    water that would result from a consumption cap would
    also pass through to Florida. See, e.g., Ga. Exh. 949 (re­
    porting streamflow data indicating several days in 2009 on
    which extra Flint River water would have passed through
    to Florida); Joint Exh. 128 (providing link to U. S. Geological
    Survey data indicating a similar trend based on streamflow
    into the Apalachicola River, including in 2016 and 2017).
    b
    Drought Operations
    The Corps’ “drought operations” are different. Again,
    whether the Corps must initiate drought operations is not
    a matter of discretion; it depends, as we have said, upon
    the total amount of water the Corps has stored behind the
    dams it controls along the Chattahoochee River. The
    Master Manual requires that, when the total amount of
    water stored in pools behind the Corps’ Chattahoochee
    dams drops below a certain level, the Corps must reduce
    the amount of water it releases from the Woodruff Dam to
    5,000 cfs, or, in instances of extreme low water levels in
    the storage pools, to 4,500 cfs. Master Manual App. A, at
    7–14 to 7–16. Accordingly, if additional water were to flow
    into Lake Seminole from the Flint River while the Corps is
    in drought operations, the Corps, pursuant to its Master
    Manual, must reduce the flow of its controlled upstream
    Chattahoochee water in order to maintain a defined water
    level in the pools behind its Chattahoochee dams, and no
    more than 4,500 cfs or 5,000 cfs can flow beyond the
    Woodruff Dam regardless. Brief for United States as
    Amicus Curiae 7.
    But even then, as we just said, the Corps must make
    certain that at least 4,500 cfs and more often 5,000 cfs
    flows though the Woodruff Dam. And, if more water flows
    from the Flint into Lake Seminole, and if the Corps uses
    that water to keep the water level high in its Chattahoo­
    chee reservoirs, then there will be fewer days in which the
    28                  FLORIDA v. GEORGIA
    Opinion of the Court
    Corps is conducting either “drought operations” or “ex­
    treme drought operations.” Instead, there will be more
    “nondrought operations” days where the Corps must pass
    most or all additional streamflow that exceeds 5,000 cfs
    through the Woodruff (because there will be more days,
    given the added Flint water, when its upstream Chatta­
    hoochee reservoirs are sufficiently high). The United
    States adds that “a cap on Georgia’s consumption” could,
    among other things, generate increased streamflow that
    “would provide a cushion during low-flow periods, so
    that it would be possible to maintain a flow rate of
    greater than 5,000 cfs for a longer period of time with­
    out any alteration of the Corps’ operations.” United
    States Post-Trial Brief 18–19 (Dec. 15, 2016) (empha­
    sis added); see also Brief for United States as Amicus
    Curiae 18 (Aug. 7, 2017) (same).
    We repeat this point with an example for purposes of
    clarity. Assume the following: (1) that it is August 13 and
    the Corps is conducting “drought operations”; (2) that as a
    result of a cap on Georgia’s consumption, 2,000 cfs more
    water flows down the Flint and into Lake Seminole; and
    (3) that, consistent with the Master Manual, 5,000 cfs will
    flow from Lake Seminole, through the Woodruff Dam, and
    into Florida’s Apalachicola River. On these three assump­
    tions in all likelihood, as the dissent points out, no extra
    water will flow into Florida.
    But (and this “but” is key), the extra 2,000 cfs of water
    that flows into Lake Seminole on August 13 as a result of
    a cap on Georgia’s from the Flint River water consumption
    will allow the Corps to store more water behind its up­
    stream Chattahoochee dams (while still complying with
    the Master Manual’s minimum release requirements).
    And that fact means that the Corps is likely to remain in
    “drought operations” for fewer days because whether the
    Corps remains in “drought operations” depends upon the
    Cite as: 585 U. S. ____ (2018)           29
    Opinion of the Court
    water level behind the Chattahoochee dams. And the
    fewer days the Corps conducts “drought operations,” the
    more days the Corps, consistent with its Master Manual,
    will allow all (or some) of the 2,000 cfs extra water that
    would result from a consumption cap to flow through the
    Woodruff Dam and into Florida’s Apalachicola River.
    Again, record evidence makes clear that this is not a
    fanciful possibility. For example, Florida points to record
    evidence that suggests a consumption cap could have
    prevented the Corps from entering drought operations in
    2011–2012 without departing from the terms of its Master
    Manual. See, e.g., Florida Brief in Support of Exceptions
    48–49, and n. 12 (citing record evidence, including Ga.
    Exh. 924 and Fla. Exh. 811, that the Special Master did
    not address suggesting that Florida’s proposed consump­
    tion cap could have helped the Corps to “avoi[d] drought
    operations entirely” in 2011–2012 without departing from
    the Master Manual’s requirements).
    The upshot is that, even when the Corps conducts its
    operations in accordance with the Master Manual, Flori­
    da’s proposed consumption cap would likely mean more
    water in the Apalachicola—as much as 2,000 cfs more
    water when the Corps is conducting normal or “non­
    drought operations,” which could take place in dry periods,
    including the driest days of summer, and 500 cfs more on
    days when the Corps is conducting “drought operations.”
    And a cap would likely allow the Corps to conduct “non­
    drought operations” (i.e., reservoirs-sufficiently-full opera­
    tions) more often as well.
    3
    We cannot agree with the dissent’s efforts to deny these
    conclusions. To begin with, the dissent says that our
    conclusion “depends on the premise that, during droughts,
    the natural streamflow into Florida is between ‘5,000 and
    10,000 cubic feet per second.’ ” Post, at 29. If the dissent
    30                   FLORIDA v. GEORGIA
    Opinion of the Court
    means by “droughts” simply dry days, or summer days,
    then it is obviously wrong, for pursuant to the Corps’
    Master Manual, the Corps must allow all or some of the
    2,000 cfs extra water that would flow into Lake Seminole
    to continue through the Woodruff Dam into Florida during
    dry summer days when the Corps is not conducting
    “drought operations.” This was true, as the dissent con­
    cedes, even during 19 summer days in 2007, which was
    among the driest years in the Basin’s history. Or, does the
    dissent mean by “droughts” days on which the Corps is
    conducting “drought operations”? If so, then we agree that
    on such days, the Corps will normally allow no more than
    5,000 cfs to flow into Florida. But, for the reasons just
    stated in the last few paragraphs, Florida’s proposed
    consumption cap—which could result in as much as 2,000
    extra cubic feet of water per second flowing from the Flint
    into Lake Seminole—will mean (consistent with the testi­
    mony of the very Georgia expert that the dissent so fre­
    quently quotes) that there will be significantly fewer such
    days.
    Is there a mistake then in the “concrete example” the
    dissent offers to support its point? See post, at 29–30.
    Invoking a hypothetical posed by Georgia’s expert, the
    dissent says:
    “[I]f the natural flows in the Apalachicola River were
    2,600 cubic feet per second, then the Corps would re­
    lease 2,400 cubic feet per second from its [Chattahoo­
    chee] reservoirs . . . . And if a cap on Georgia[’s Flint
    River consumption] increased the River’s natural flow
    to 4,100 cubic feet per second, the Corps would release
    900 cubic feet per second. . . . In either case, the total
    flow on the Apalachicola River would remain the
    same: 5,000 cubic feet per second. Thus, so long as
    the natural flows remain significantly less than 5,000
    cubic feet per second, a cap on Georgia would only de­
    Cite as: 585 U. S. ____ (2018)          31
    Opinion of the Court
    crease the amount of water that the Corps releases
    from storage; it would not increase the overall amount
    of water flowing into the Apalachicola River.” 
    Id., at 29–30
    (citing Bedient ¶¶45–47).
    If, however, a consumption cap causes 1,500 cfs extra
    water (from the Flint) to flow into Lake Seminole (as we
    assume Florida’s proposed cap would), under the dissent’s
    example, the Corps will reduce (or “offset”) the amount of
    water it releases from its upstream Chattahoochee dams
    from 2,400 cfs to 900 cfs. That is because 2,400 cfs minus
    900 cfs is 1,500 cfs. What happens to that 1,500 cfs extra
    water?
    When the Corps is in drought operations, the answer
    according to the Master Manual is that the Corps must
    store that water in its upstream Chattahoochee reservoirs.
    And with that 1,500 cfs extra water each day, the water
    levels in those reservoirs will rise (or, at a minimum,
    deplete less rapidly) and allow the Corps to resume “non­
    drought operations” more quickly. The United States
    repeats precisely this point—namely, when more water
    flows into Lake Seminole, it benefits Florida by “quicken­
    ing the [Corps’] resumption of normal [i.e., “nondrought”]
    operations.” Brief for United States as Amicus Curiae 28
    (Aug. 7, 2017). (That extra water also means that there
    will be more days when 5,000 cfs, rather than 4,500 cfs,
    flows from Lake Seminole into the Apalachicola River).
    And it means, as no one denies, that on days when the
    Corps conducts “nondrought operations” (which, as Geor­
    gia’s own expert report shows, occur even during dry
    summer months), more water will reach Florida when
    Florida needs it.
    What about the dissent’s point that Georgia’s expert, Dr.
    Bedient, said that the extra 2,000 cfs would mean more
    water for Florida “only 19 days ‘during the summer and
    fall months when streamflow was at its lowest’ ”? Post, at
    32                   FLORIDA v. GEORGIA
    Opinion of the Court
    30. Dr. Bediant’s exact words, as the dissent points out,
    were that in “ ‘dry years (e.g., 2007 and 2011), . . . even
    significant changes in Georgia’s consumptive use would
    lead to virtually no change in state-line flows during the
    low-flow months (e.g., June, July, August, September).’ ”
    Bedient ¶¶48–53.
    At this point, in our view, the dissent has pointed to
    record evidence with which other record evidence conflicts.
    It seems from record evidence, from the statements of the
    United States, from geological data, and from laws of
    mechanics, that 2,000 cfs extra water flowing into Lake
    Seminole when, in the dissent’s words, “drought opera­
    tions were not in effect” would have to mean more water in
    Florida. Post, at 30. And the dissent does not dispute that
    some of these days are in the summer. 
    Ibid. Our own check
    of the record reinforces the point. In particular,
    data from the U. S. Geological Survey’s website, which the
    parties entered into the record at Joint Exh. 128, indicates
    that between May 2016 and August 2016, streamflow into
    the Apalachicola River was above 6,000 cfs each day with the
    exception of two days: August 30, 2016 and August 31, 2016.
    Nothing in the record suggests that the Corps was in
    drought operations during these days, and so it appears that
    under these conditions, any additional streamflow resulting
    from a cap on Georgia’s Flint River consumption would pass
    through into Florida. However, without explicit findings, it
    is neither possible nor prudent for us in the first instance
    to read through this voluminous record and discover who
    is right on this matter of how much extra water there will
    be, when, and how much Florida would benefit from the
    extra water that there might be. That is why we are
    sending this case back for more findings.
    Finally, while the dissent suggests that “[i]t is incredibly
    odd to conclude that a Special Master’s merits determina­
    tion is ‘premature’ after a full trial,” post, at 17, this Court
    has repeatedly concluded that remand is “appropriate” to
    Cite as: 585 U. S. ____ (2018)           33
    Opinion of the Court
    resolve certain issues in an equitable apportionment case
    even where, as here, there has already been a “lengthy
    trial at which both States presented extensive evidence.”
    Colorado 
    II, 467 U.S., at 313
    ; see also Wyoming v. Colo-
    
    rado, 259 U.S., at 456
    –457 (explaining that “the evidence
    was taken” over the course of two years and presented to
    the Court two years later and that “[t]he case has been
    argued at bar three times” including because of the “im­
    portance of some of the questions involved”). Moreover,
    we note that adequate factfinding is especially important
    where, as here, no interstate compact guides our inquiry
    or sets forth a congressionally ratified water allocation
    formula. When such a compact exists, as it often does, our
    effort is relatively simple and focuses upon “declar[ing]
    rights under the Compact and enforc[ing] its terms.”
    Kansas v. Nebraska, 574 U. S., at ___ (slip op., at 8) (citing
    Texas v. New 
    Mexico, 462 U.S., at 567
    ); 
    id., at 567–568
    (“If there is a compact, it is a law of the United States, and
    our first and last order of business is interpreting the
    compact”). Here, no compact guides our inquiry and it
    would appear to be important that we approach this com­
    plex controversy with the care and thoroughness that our
    precedent requires.
    E
    Our final question is this: Would the amount of extra
    water that reaches the Apalachicola significantly redress
    the economic and ecological harm that Florida has suf­
    fered? There is evidence indicating that the answer to the
    question is in the affirmative. See, e.g., Allan ¶3d, 26, 67
    (“Even relatively modest increases in flows—on the order
    of 300 to 500 cfs during key periods of the year—could
    reduce harm to the [Apalachicola Region’s] ecosystem and
    halt the cycle that is leading to irreversible harm” while
    “[g]reater increases could make even more dramatic im­
    provements”); Updated PFDT of Patricia Glibert ¶¶5, 28–
    34                  FLORIDA v. GEORGIA
    Opinion of the Court
    32, 58–60, and Table 1, Figs. 10, 
    19b; supra, at 21
    –22
    (citing record evidence of benefits); see also 10 Tr. 2629:7–
    15 (Kondolf) (detailing benefits of increasing streamflow
    from 5,000 to 7,000 cfs); 3 
    id., at 591:6–593:4,
    596:17–
    598:1 (Allan). But the Master’s Report does not explicitly
    answer this question. We consequently must remand the
    case to find the answer to this question (and others).
    *    *    *
    In sum, in respect to the evidentiary questions at issue,
    the Master assumed that: (1) Florida has likely suffered
    harm as a result of decreased water flow into the Apala­
    chicola River; (2) Florida has made some showing that
    Georgia, contrary to equitable principles, has taken too
    much water from the Flint River; and (3) Georgia’s inequi­
    table use of the water may have injured Florida, but more
    findings are needed. And in light of the Master’s assump­
    tions, we conclude that: (4) an equity-based cap on Geor­
    gia’s use of the Flint River would likely lead to a material
    increase in streamflow from the Flint River into Florida’s
    Apalachicola River; and (5) the amount of extra water that
    reaches the Apalachicola may significantly redress the
    economic and ecological harm that Florida has suffered.
    Further findings, however, are needed on all of these
    evidentiary issues on remand.
    We add the following: The United States has made clear
    that the Corps will work to accommodate any determina­
    tions or obligations the Court sets forth if a final decree
    equitably apportioning the Basin’s waters proves justified
    in this case. It states in its brief here that if a decree
    results “in more water flowing to Florida . . . under exist­
    ing Corps protocols, then the Corps would likely not need
    to change its operations.” Brief for United States as Ami-
    cus Curiae 28 (Aug. 7, 2017). It has added that, in any
    event, a decree “would necessarily form part of the constel­
    lation of laws to be considered by the Corps when deciding
    Cite as: 585 U. S. ____ (2018)            35
    Opinion of the Court
    how best to operate the federal projects.” 
    Id., at 32.
    And
    in issuing its revised Master Manual, the Corps stated
    that it would “review any final decision from the U. S.
    Supreme Court and consider any operational adjustments
    that are appropriate in light of that decision, including
    modifications to the then-existing [Master Manual], if
    applicable.” Record of Decision 18. The United States has
    “continually asserted its preparedness to implement, in
    accordance with federal law, any [agreed-upon] compre­
    hensive water allocation formula.” 
    Id., at 4;
    see also Joint
    Exh. 124, at 6–35. And, of course, the Administrative Proce­
    dure Act requires the Corps to make decisions that are
    reasonable, i.e., not “arbitrary, capricious, an abuse of dis-
    cretion” or “in excess of [the Corps’] statutory jurisdiction.”
    
    5 U.S. C
    . §706(2).
    We recognize that the Corps must take account of a
    variety of circumstances and statutory obligations when it
    allocates water. New circumstances may require the
    Corps to revise its Master Manual or devote more water
    from the Chattahoochee River to other uses. But, given
    the considerations we have set forth, we cannot agree with
    the Special Master that the Corps’ “inheren[t] discretio[n]”
    renders effective relief impermissibly “uncertain” or that
    meaningful relief is otherwise precluded. Report 56, n. 38.
    We cannot now say that Florida has “merely some tech­
    nical right” without “a corresponding benefit,” Kansas 
    I, 206 U.S., at 109
    , or that an effort to shape a decree will
    prove “a vain thing.” 
    Foster, 146 U.S., at 101
    . Ordinarily
    “[u]ncertainties about the future” do not “provide a basis
    for declining to fashion a decree.” See Idaho 
    II, 462 U.S., at 1026
    . And in this case, the record leads us to believe
    that, if necessary and with the help of the United States,
    the Special Master, and the parties, we should be able to
    fashion one.
    36                  FLORIDA v. GEORGIA
    Opinion of the Court
    V
    We keep in mind what our prior decisions make clear:
    “ ‘The difficulties of drafting and enforcing a decree’ ” do
    not necessarily provide a convincing “ ‘justification for us
    to refuse to perform the important function entrusted to
    us by the Constitution.’ ” Idaho 
    I, 444 U.S., at 390
    , n. 7
    (quoting Nebraska v. 
    Wyoming, 325 U.S., at 616
    ); see also
    Idaho 
    II, supra, at 1027
    (“Although the computation is
    complicated and somewhat technical, that fact does not
    prevent the issuance of an equitable decree”). For this
    reason and the others we have discussed, we agree with
    Florida that it has made a legally sufficient showing as to
    the possibility of fashioning an effective remedial decree.
    We repeat, however, that Florida will be entitled to a
    decree only if it is shown that “the benefits of the [appor­
    tionment] substantially outweigh the harm that might
    result.” Colorado 
    I, 459 U.S., at 187
    . In assessing whether
    that showing has been made, the Master may find it
    necessary to address in the first instance many of the
    evidentiary and legal questions the answers to which we
    have here assumed or found plausible enough to allow us
    to resolve the threshold remedial question. In order to
    determine whether Florida can eventually prove its right
    to cap Georgia’s use of Flint River waters, it may find it
    necessary for the Special Master to make more specific
    factual findings and definitive recommendations regarding
    such questions as: To what extent does Georgia take too
    much water from the Flint River? To what extent has
    Florida sustained injuries as a result? To what extent
    would a cap on Georgia’s water consumption increase the
    amount of water that flows from the Flint River into Lake
    Seminole? To what extent (under the Corps’ revised Mas­
    ter Manual or under reasonable modifications that could
    be made to that Manual) would additional water resulting
    from a cap on Georgia’s water consumption result in addi­
    tional streamflow in the Apalachicola River? To what
    Cite as: 585 U. S. ____ (2018)           37
    Opinion of the Court
    extent would that additional streamflow into the Apala­
    chicola River ameliorate Florida’s injuries? The Special
    Master may make other factual findings he believes neces­
    sary and hold hearings (or take additional evidence) as he
    believes necessary. Cf. Colorado 
    I, 459 U.S., at 190
    , n. 14.
    Consistent with the principles that guide our inquiry in
    this context, answers need not be “mathematically precise
    or based on definite present and future conditions.” 
    Id., at 1026.
    Approximation and reasonable estimates may prove
    “necessary to protect the equitable rights of a State.” 
    Ibid. And the answers
    may change over time. Cf. New Jersey v.
    New York, 
    347 U.S. 995
    , 996–1005 (1954); New Jersey v.
    New 
    York, 283 U.S., at 344
    –346. Flexibility and approx­
    imation are often the keys to success in our efforts to
    resolve water disputes between sovereign States that
    neither Congress “nor the legislature of either State” has
    been able to resolve. Virginia v. West 
    Virginia, 220 U.S., at 27
    .
    We consequently do not dismiss this case. Rather, we
    remand the case to the Special Master for further proceed­
    ings consistent with this opinion.
    It is so ordered.
    38       FLORIDA v. GEORGIA
    Opinion
    Appendix      of the of
    to opinion  Court
    the Court
    APPENDIX
    Cite as: 585 U. S. ____ (2018)              1
    THOMAS, J., dissenting
    SUPREME COURT OF THE UNITED STATES
    _________________
    No. 142, Orig.
    _________________
    STATE OF FLORIDA, PLAINTIFF
    v. STATE OF GEORGIA
    ON EXCEPTIONS TO REPORT OF SPECIAL MASTER
    [June 27, 2018]
    JUSTICE THOMAS, with whom JUSTICE ALITO, JUSTICE
    KAGAN, and JUSTICE GORSUCH join, dissenting.
    Florida asks this Court to cap Georgia’s use of water in
    the Apalachicola-Chattahoochee-Flint River Basin (Basin).
    Florida claims that such a cap would allow additional
    water to flow into the Apalachicola River and Bay, which
    would benefit Florida by alleviating certain ecological
    harms. To prevail under our precedents, Florida must
    present clear and convincing evidence that its proposed
    cap will benefit Florida more than it harms Georgia. See
    Colorado v. New Mexico, 
    459 U.S. 176
    , 187 (1982) (Colo-
    rado I ). The Special Master applied this balance-of-harms
    standard and, after presiding over a 1-month trial involv­
    ing 40 witnesses and more than 2,000 exhibits, found that
    Florida had not met its burden. Because that finding
    is well supported by the evidence, I would have over-
    ruled Florida’s objections to the Special Master’s Report
    (Report) and denied Florida’s request for relief. I respectfully
    dissent.
    I
    The Court’s recitation of the facts focuses on the geogra­
    phy of the relevant rivers and the failed compact negotia­
    tions between Florida and Georgia, but does not provide
    any details about the respective interests of Florida and
    Georgia or the extensive operations of the United States
    2                   FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    Army Corps of Engineers (Corps). See ante, at 2–5. Be­
    cause these missing details are crucial to determining
    whether equitable relief is warranted, I will supply them.
    A
    This case concerns Georgia’s use of water in the Basin.
    Spanning Georgia, Alabama, and Florida, the Basin con­
    sists of three rivers—the Chattahoochee, the Flint, and
    the Apalachicola. The Chattahoochee River starts in
    northern Georgia, just north of Atlanta, and flows south­
    west along the Alabama-Georgia border until it reaches
    Florida. The Flint River starts east of the Chattahoochee,
    just south of Atlanta, and flows south until it reaches
    Florida. The Chattahoochee and Flint Rivers meet at the
    border of Florida, forming Lake Seminole. From Lake
    Seminole, the Apalachicola River flows south through the
    Florida panhandle and into the Gulf of Mexico at Apala­
    chicola Bay.
    Both Georgia and Florida depend on Basin water. The
    Chattahoochee River supplies most of the water for met­
    ropolitan Atlanta. And the Flint River supplies most of
    the water for southern Georgia’s large agricultural indus­
    try. In Florida, the Apalachicola River sustains a unique
    ecosystem that is home to a number of species, including
    mussels, sturgeon, and tupelo trees. Flows from the
    Apalachicola River (or River) also support the Apalachi-
    cola Bay (or Bay) ecosystem—one of the most productive
    estuaries in the Northern Hemisphere. The Apalachicola
    Bay’s low-salinity and high-nutrient waters make it an
    extraordinarily productive habitat for oysters and other
    sea life.
    Although both Georgia and Florida depend on the Basin,
    the Florida portion of the Basin is significantly less popu­
    lated and productive. The Georgia portion has a popula­
    tion of more than 5 million and accounts for around $283
    billion in gross regional product per year. Direct Testimony
    Cite as: 585 U. S. ____ (2018)           3
    THOMAS, J., dissenting
    of Robert Stavins 2, 16 (Stavins). The Florida portion, by
    contrast, has a population of fewer than 100,000 people
    and generates around $2 billion in gross regional product
    per year. 
    Id., at 17.
    In relative terms, Georgia accounts
    for 98% of the population and 99% of the economic produc­
    tion. 
    Ibid. B Florida and
    Georgia are not the only stakeholders in the
    Basin. The United States, through the Corps, operates
    five dams and four reservoirs on the Chattahoochee River.
    Only the three northernmost dams can store significant
    amounts of water. The two dams that are farthest south
    on the Chattahoochee—the George W. Andrews Dam and
    the Jim Woodruff Dam—cannot store an appreciable
    amount of water. The Corps does not operate any dams on
    the Flint River, which flows unimpeded until it reaches
    the Jim Woodruff Dam at Lake Seminole.
    The Corps operates its dams as a unit. It must do so in
    a way that achieves its congressionally authorized purposes,
    such as facilitating navigation, generating hydroelectric
    power, protecting the national defense, promoting recrea­
    tion, maintaining the commercial value of riparian lands,
    and protecting the water supply for the surrounding met­
    ropolitan Atlanta area. See H. R. Doc. No. 342, 76th
    Cong., 1st Sess., 77 (1939); River and Harbor Act of 1945,
    59 Stat. 17; In re MDL-1824 Tri-State Water Rights Litiga-
    tion, 
    644 F.3d 1160
    , 1167 (CA11 2011). The Corps also
    must ensure compliance with other federal laws, including
    laws governing the conservation of fish and wildlife, the
    quality of water, and the protection of threatened and
    endangered species. See, e.g., Endangered Species Act of
    1973, 
    16 U.S. C
    . §1531 et seq.; Flood Control Act of 1944,
    
    33 U.S. C
    . §701 et seq.; Water Supply Act of 1958, 
    43 U.S. C
    . §390b.
    Given these numerous demands, the Corps has long
    4                        FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    relied on water-control manuals to guide its operations of
    the dams. The current manual dictates the minimum
    amount of water that the Corps must provide to the
    Apalachicola River under various conditions. Three vari-
    ables affect that minimum amount of water: the time of
    year, the amount of water in the Corps’ storage reservoirs,
    and the amount of additional water entering the Basin.
    The manual is very complex, spanning 1,190 pages, but
    only a few provisions are relevant here. The manual
    provides that, as a general rule, most additional water
    that enters the Basin will pass through to Florida via the
    Apalachicola River. But, in certain circumstances, the
    Corps will artificially increase or decrease the amount of
    water that passes through to ensure that 5,000 cubic feet
    per second flows into the Apalachicola River. For exam­
    ple, if the natural streamflow entering the Basin (Basin
    inflow) is less than 5,000 cubic feet per second, then the
    Corps will artificially augment the flow by releasing addi­
    tional water from its reservoirs. Or, if the amount of
    water in the Corps’ reservoirs falls below a certain
    amount, the Corps will trigger what it calls “drought
    operations.” During drought operations, no matter how
    much water is entering the Basin, the Corps will generally
    release only 5,000 cubic feet per second into the Apa-
    lachicola River until its reservoirs are completely
    replenished.1
    The Corps’ current manual reflects many lessons that it
    has learned over the past decade. In March 2006, for
    example, the Corps created an interim operating plan,
    which set high flow requirements to protect endangered
    ——————
    1 If the amount of water in the Corps’ reservoirs falls to critically low
    levels, then the Corps will release only 4,500 cubic feet per second into
    the Apalachicola River. These extreme drought operations have not
    been triggered in recent droughts. See Direct Testimony of Phillip
    Bedient 14 (Bedient). (showing that flows remained around 5,000 cubic
    feet per second during the 2011 and 2012 droughts).
    Cite as: 585 U. S. ____ (2018)                   5
    THOMAS, J., dissenting
    species in the Apalachicola River. Direct Testimony of
    Wei Zeng 44–45 (Zeng). But those high flow requirements
    prevented the Corps from saving enough water during
    droughts to refill its reservoirs, putting all its other pro­
    jects at risk. 
    Id., at 45.
    So the Corps switched to more
    storage-friendly rules. 
    Id., at 45–46.
    In December 2006,
    the Corps modified its operating plan to require a portion
    of the water entering the Basin to be devoted to refilling
    the Corps’ reservoirs. 
    Id., at 46.
    When this modification
    proved insufficient, the Corps created special rules for
    droughts, which saved even more water by decreasing the
    minimum flow into the Apalachicola River. 
    Id., at 46–47.
    Later, the Corps altered its operations to save still more
    water, by increasing the amount it could dedicate to refill­
    ing its reservoirs during nondroughts and lowering the
    threshold for triggering the special drought rules. 
    Id., at 47
    ; Brief for United States as Amicus Curiae 11 (Brief for
    United States). The Corps’ current manual is a product of
    this decade of trial and error.
    The current manual also reflects decades of litigation.
    The Corps’ first manual went into effect in 1958, and the
    Corps did not propose a new one until 1989. As soon as it
    did, Alabama sued. Florida, Georgia, and other stake­
    holders eventually sued as well. For its part, Florida
    alleged that the Corps’ operations under the proposed
    manual and subsequent interim operating plans violated
    the Endangered Species Act by injuring mussels and
    sturgeon, as well as noncovered species like oysters and
    tupelo trees.2 The various lawsuits were eventually con­
    solidated in the Middle District of Florida. Twenty years
    after Alabama first sued, the District Court ruled for
    ——————
    2 TheU. S. Fish and Wildlife Service did not agree. It concluded that
    the minimum flows in the proposed manual and interim operating
    plans were sufficient to protect endangered species in the Apalachicola
    River. Zeng 46–47.
    6                   FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    Alabama but against Florida. The United States Court of
    Appeals for the Eleventh Circuit reversed with respect to
    Alabama. In re MDL-1824 Tri-State Water Rights Litiga-
    
    tion, 644 F.3d, at 1192
    , 1205. And Florida’s case became
    moot in 2012, once the Corps issued the immediate prede­
    cessor to its current manual.
    II
    A
    Soon after the litigation against the Corps ended, Florida
    sought leave to file this lawsuit against Georgia, request­
    ing an equitable apportionment of Basin water. This
    Court granted Florida leave to file its complaint in 2014.
    Florida’s complaint alleged that Georgia was consuming
    more than its fair share of water in the Basin, causing
    economic and ecological harms to Florida. Florida sought
    relief only against Georgia and disclaimed seeking any
    “affirmative relief against the United States . . . with
    respect to the Corps’ operation of the federally authorized
    dam and reservoir system.” Complaint ¶15. The United
    States could not be joined as a party because it declined to
    waive its sovereign immunity.
    Georgia moved to dismiss Florida’s complaint for failure
    to join the United States as a necessary party. Florida
    opposed the motion, arguing that the United States was
    not necessary because Florida “ ‘ha[d] no quarrel’ with the
    Corps’ operation of dams, and [its] lawsuit is not seeking
    to impose a ‘minimum flow’ regime on the Corps.” Florida
    Brief in Opposition to Motion to Dismiss 26. Florida
    reiterated that it “is not seeking any relief whatsoever
    with respect to the operations of the dams” and is “not
    seeking any relief asking the Corps to control the dams or
    pull the levers in any specific way.” Tr. of Oral Arg. on
    Motion to Dismiss 27. Florida conceded that “if [the Spe­
    cial Master] conclude[s] after a trial that caps on [Geor­
    gia’s] consumption will not redress Florida’s harm, then
    Cite as: 585 U. S. ____ (2018)           7
    THOMAS, J., dissenting
    Florida will not have proved its case.” 
    Id., at 29.
       Based on Florida’s concessions, the Special Master
    denied Georgia’s motion to dismiss. The Special Master
    recognized that Florida had “disclaimed any intention to
    seek a decree” binding the Corps in order to “sideste[p] the
    need to join the United States as a party.” Order on Mo­
    tion to Dismiss, p. 12. The Special Master warned Florida
    that this strategy was a “ ‘two edged sword.’ ” 
    Id., at 13.
    “Having voluntarily narrowed its requested relief and
    shouldered the burden of proving that the requested relief
    is appropriate,” the Special Master explained, “Florida’s
    claim will live or die based on whether Florida can show
    that a consumption cap [on Georgia alone] is justified and
    will afford adequate relief.” 
    Ibid. B The parties
    proceeded to trial. Florida sought to cap
    Georgia’s use of Basin water at its current levels through
    at least 2050. See Florida Pre-trial Brief 5; Updated Pre-
    Filed Direct Testimony (PFDT) of Dr. George M. Horn­
    berger 58 (Hornberger). And, during drought years, Florida
    sought to reduce Georgia’s use of Basin water by between
    1,500 and 2,000 cubic feet per second. See Florida Pre­
    trial Brief 5; Hornberger 58; Updated PFDT of David
    Sunding 42 (Sunding); Florida Post-Trial Brief 18.
    To support its proposed caps, Florida first presented
    testimony about how much additional water it would
    receive during droughts. According to Florida’s evidence,
    Georgia is currently using enough water during droughts
    to decrease streamflow on the Apalachicola River by
    around 4,000 cubic feet per second. See Hornberger 2.
    Florida proposed cutting that amount by half. One of its
    experts opined that, by implementing several conservation
    measures, Georgia could increase flows in the Apalachicola
    River during droughts by 1,500 to 2,000 cubic feet per
    second. See Sunding 3; Hornberger 4. Florida estimated
    8                   FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    that these measures would cost Georgia an additional
    $35.2 million per year. Sunding 44.
    Florida next presented evidence about how this addi­
    tional water would benefit various species in the Apala­
    chicola River. It argued that additional flows could benefit
    mussels, which need consistent flows of at least 6,000
    cubic feet per second in the summer; sturgeon, which need
    consistent flows of at least 7,000 cubic feet per second in
    the summer; and tupelo trees, which need consistent flows
    of at least 14,100 cubic feet per second in the summer. See
    Updated PFDT of J. David Allan 23–24, 26, 32–33, 41, 44–
    45 (Allan). Additional flows could also benefit the oysters
    in the Apalachicola Bay by lowering its salinity. See
    Updated PFDT of J. Wilson White 48 (White); PFDT of
    Marcia Greenblatt 15. All of Florida’s evidence about
    these species, however, addressed the benefits of additional
    water during droughts. See Report 63. Florida presented
    no evidence of any benefits during nondroughts.
    Finally, Florida attempted to prove that the additional
    water would actually reach Florida when it needs the
    water—i.e., during droughts. To do this, Florida needed to
    show that the Corps would deviate from its normal operat­
    ing protocols, which specify that the Corps will generally
    release only 5,000 cubic feet per second during droughts.
    Florida relied on Dr. Peter Shanahan to make this show­
    ing. Dr. Shanahan testified that “the Corps would not . . .
    hold back water and thwart the additional flow benefits
    [that] Florida would receive from Georgia[’s] conservation
    efforts.” Updated PFDT of Dr. Peter Shanahan 1 (Nov. 15,
    2016). He reasoned that the Corps would either choose to
    release the additional water in its discretion or be com­
    pelled to release the additional water because its up­
    stream dams have limited storage capacity and it does not
    operate any dams on the Flint River. 
    Id., at 17–27.
       In its defense, Georgia presented evidence that its cur­
    rent use has only a negligible impact on the amount of
    Cite as: 585 U. S. ____ (2018)            9
    THOMAS, J., dissenting
    water that Florida receives through the Apalachicola
    River. Georgia’s experts showed that the State’s water
    use amounted to just 4% of Basin flows in an average year
    and 8% of Basin flows in a dry year, leaving anywhere
    from 92% to 96% of Basin water for Florida. See Stavins
    16–18; Bedient 44–45. According to Georgia’s experts, the
    primary factor that dictates flows in the Apalachicola
    River is precipitation, not consumption. See Direct Testi­
    mony of Charles A. Menzie 15.
    Georgia’s experts also testified that Georgia’s water use
    was entirely reasonable. Metropolitan Atlanta had taken
    substantial steps to conserve water, reducing its consump­
    tion to levels that even Florida’s expert admitted demon­
    strated effective water conservation. Direct Testimony of
    Peter Mayer 2; see also, 
    id., at 18
    (showing that Florida’s
    Basin residents used more water per capita than residents
    in metropolitan Atlanta). And, instead of Florida’s esti­
    mate of 4,000 cubic feet per second, Georgia estimated
    that its water use had never decreased streamflow by
    more than 2,000 cubic feet per second, and only rarely by
    more than 1,400 cubic feet per second. See Zeng 2, 7.
    Georgia also presented evidence that Florida’s proposed
    caps would cost Georgia significantly more than they
    would benefit Florida. Georgia’s economic expert estimated
    that Florida’s proposed caps would impose costs of more
    than “$2.1 billion for municipal and industrial water users
    and $335 million for Georgia farmers . . . every single
    year.” Stavins 2. Georgia’s expert also testified that
    Florida’s expert had dramatically lowered his initial eval­
    uation of the costs to Georgia, which was initially $191
    million. 
    Id., at 31
    ; see also 11 Trial Tr. 2787. That change
    apparently occurred because Florida’s expert narrowed his
    definition of “cost” to exclude anything but additional,
    direct governmental expenditures. See 
    id., at 2
    791. But
    regardless of the precise cost, Georgia’s expert testified
    that it would be inequitable to impose it on Georgia.
    10                     FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    “Georgia has 5 times the land area, 56 times the popula­
    tion, 80 times the number of employees, and 129 times the
    [gross regional product] of . . . Florida. [Yet it] consumes
    only 4 percent of the total waters available in the . . .
    Basin in an average year, and only 8 percent of the total
    waters available in the . . . Basin in a dry year, leaving the
    rest for Florida’s use.” Stavins 2. Further, Florida’s own
    expert estimated that a cap on Georgia would produce only
    minimal benefits for Florida: Cutting Georgia’s water use
    in half would increase the oyster biomass in Apalachicola
    Bay by less than 0.6% in most instances, and only 1.2%
    during the worst droughts. White 50–51. These additional
    oysters would be worth only a few hundred thousand
    dollars. Stavins 51–52.
    Finally, Georgia rebutted Florida’s assertion that, de­
    spite the Corps’ operations, Florida would actually receive
    the additional water that a cap on Georgia would create
    during droughts. Using models that accounted for the
    Corps’ prior operations, Georgia’s expert on the Corps, Dr.
    Philip Bedient, testified that Florida would receive only
    5,000 cubic feet per second during droughts, no matter
    how much additional water was created by a cap on Geor­
    gia and regardless of whether that water flowed into the
    Flint or the Chattahoochee River. See Bedient 23–26, 28–
    30. The United States filed an amicus brief to the same
    effect. It confirmed that, during droughts, “[t]he Corps
    expects . . . that Apalachicola River flows would be very
    similar with or without a consumption cap [on Georgia].”
    Post-Trial Brief 17–18 (United States Post-Trial Brief ).3
    ——————
    3 The United States has made similar representations to this Court.
    See, e.g., Brief for United States 26–29 (explaining that the Corps
    “would not generally expect” flows into Florida to increase during
    droughts, even if Florida convinced this Court to cap Georgia’s water
    use).
    Cite as: 585 U. S. ____ (2018)                  11
    THOMAS, J., dissenting
    C
    All told, the trial lasted one month. After hearing the
    witnesses and reviewing the evidence, the Special Master
    recommended ruling against Florida. Report 70. The
    Special Master found that Florida likely had proved harm
    to its oysters,4 and assumed that Georgia was using too
    much water for agricultural purposes.5 
    Id., at 31
    –34. But
    the Special Master did not decide whether Georgia’s agri­
    cultural water use caused the harm to Florida’s oysters.
    
    Id., at 34.
    Instead, he concluded that Florida had failed to
    prove that a cap on Georgia would appreciably benefit it
    given the Corps’ operations in the Basin. 
    Id., at 3,
    31–34.
    Citing this Court’s precedents requiring States to prove
    an appreciable benefit before they can obtain an equitable
    apportionment that interferes with established uses, the
    Special Master concluded that Florida could not prove that
    its injury was “redressable by the Court.” See 
    id., at 2
    4
    (citing, inter alia, Idaho ex rel. Evans v. Oregon, 
    444 U.S. 380
    , 392 (1980) (Idaho I ); Washington v. Oregon, 
    297 U.S. 517
    , 523 (1936)); Report 30 (same); see also 
    id., at 2
    7
    (citing New Jersey v. New York, 
    283 U.S. 336
    , 342–345
    (1931); Colorado 
    I, 459 U.S., at 187
    ). According to the
    Special Master, Florida “ha[d] not proven by clear and
    convincing evidence that any additional streamflow in the
    Flint River or Chattahoochee River would be released
    from Jim Woodruff Dam into the Apalachicola River at a
    time that would provide a material benefit to Florida (i.e.,
    during dry periods).” Report 47. The Special Master also
    found that “Florida ha[d] not met its requirement to show
    by clear and convincing evidence that its injury can be
    ——————
    4 The Special Master noted that Florida’s alleged injuries to mussels,
    sturgeon, and tupelo trees were “less compelling.” Report 64, n. 42.
    5 As for Georgia’s municipal and industrial water use, the Special
    Master concluded that it was “less clear” that these uses were “unrea­
    sonable,” given that Georgia had “taken significant steps to conserve
    water in the Atlanta metropolitan region.” 
    Id., at 34,
    n. 28.
    12                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    redressed by increased flows during nondrought condi­
    tions” because its “trial presentation did not address the
    benefits of increased flows during ‘normal’ periods” and
    Georgia’s evidence showed “an absence of any significant
    benefit to Florida.” 
    Id., at 63–65.
                                 III
    Before delving into the parties’ arguments, it is helpful
    to have a basic understanding of the rules that govern this
    Court’s equitable-apportionment jurisprudence—or at
    least what used to be the rules before the Court’s opinion
    muddled them beyond recognition.
    First, in equitable-apportionment cases, as in all cases,
    this Court requires the complaining party to prove stand­
    ing. Maryland v. Louisiana, 
    451 U.S. 725
    , 735–736
    (1981); Wyoming v. Oklahoma, 
    502 U.S. 437
    , 447, 452
    (1992); see also 3 A. Kelley, Water and Water Rights
    §45.02(b), p. 45–12 (3d ed. 2018) (noting that standing is a
    justiciability requirement for equitable-apportionment
    cases) (Kelley). To prove standing, a complaining State
    must demonstrate that it has “ ‘suffered a wrong through
    the action of the other State . . . which is susceptible of
    judicial enforcement according to the acceptable principles
    of the common law or equity systems of jurisprudence.’ ”
    
    Maryland, supra, at 735
    –736; 
    Wyoming, supra, at 452
    .
    Second, this Court requires the State seeking an appor­
    tionment to show by clear and convincing evidence a
    “threatened invasion of rights . . . of serious magnitude.”
    New York v. New Jersey, 
    256 U.S. 296
    , 309 (1921); accord,
    Colorado 
    I, supra, at 187
    , n. 13; Kelley §45.04. Our prece­
    dents do not clarify whether this requirement goes to the
    case’s justiciability, the merits of the complaining State’s
    claim, or the propriety of affording injunctive relief. See
    
    ibid. But they are
    clear that such a showing must be
    made to obtain relief. See Connecticut v. Massachusetts,
    
    282 U.S. 660
    , 669 (1931).
    Cite as: 585 U. S. ____ (2018)          13
    THOMAS, J., dissenting
    Third, the State seeking an apportionment must
    “demonstrat[e] by clear and convincing evidence that the
    benefits of the [apportionment] substantially outweigh the
    harm that might result.” Colorado 
    I, supra, at 187
    ; ac­
    cord, Colorado v. New Mexico, 
    467 U.S. 310
    , 316–317
    (1984) (Colorado II ); Kelley §45.06, at 45–34 to 45–35.
    Since this Court’s first equitable-apportionment case, this
    balance-of-harms test has been the basic merits inquiry
    that decides whether a State is entitled to an apportion­
    ment. See 
    id., §45.06(c)(1), at
    45–39 to 45–40 (“Harm­
    benefit comparison goes back to the Court’s first equitable
    apportionment case, Kansas v. Colorado[, 
    206 U.S. 46
    ,
    113–114 (1907) (Kansas I)]”). As part of the balance-of­
    harms test, this Court has required the State seeking an
    apportionment to prove that it would appreciably benefit
    from the apportionment—otherwise, the State could not
    possibly prevail in the balance-of-harms analysis. Idaho 
    I, supra, at 392
    ; 
    Washington, supra, at 523
    ; see also Kelley
    §45.06(c)(1), at 45–39 (explaining that this appreciable-
    benefit requirement is part of the “harm-benefit” balance).
    Fourth, if the State seeking an apportionment makes all
    these showings, this Court must craft an equitable-
    apportionment decree. Our precedents hold that a State
    should not be denied a remedy merely because calculating
    the appropriate apportionment is difficult. See Idaho
    ex rel. Evans v. Oregon, 
    462 U.S. 1017
    , 1026 (1983) (Idaho
    II). Reasonable predictions about future conditions are
    sufficient. 
    Ibid. This case is
    about the third rule: the balance-of-harms
    analysis and, specifically, its appreciable-benefit require­
    ment. The Special Master found that Florida had not
    proved that its requested cap on Georgia’s water use
    would appreciably benefit it, since Florida could not prove
    that it would receive more water when it needed it. That
    this case is about the third rule is important. Throughout
    its opinion, the Court mushes the requirements from our
    14                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    precedents together, merging cases and principles from
    one area with cases and principles from another—
    sometimes in the same sentence. But our precedents are
    not so convoluted. They articulate clear rules, and the
    Special Master correctly applied one of them when making
    his recommendation in this case. He did not err by failing
    to apply the unrecognizable mishmash of principles set out
    in the Court’s opinion.
    IV
    Florida raises three objections to the Special Master’s
    Report. First, it argues that the Special Master required
    it to satisfy a legal standard that was too demanding.
    Second, Florida argues that it should prevail under the
    correct standard because, if this Court enters an equitable-
    apportionment decree, the Corps will likely allow more
    water to flow into Florida during droughts. And third,
    even if the Corps does not release more water into Florida
    during droughts, Florida argues that a cap on Georgia
    would still benefit it during nondroughts. None of these
    arguments has merit.
    A
    Florida’s first objection fails because the Special Master
    applied the correct legal standard. A careful reading of his
    Report demonstrates that he applied the ordinary balance-
    of-harms test dictated by this Court’s precedents. He did
    not, as the Court implies, deny Florida relief because
    calculating an appropriate apportionment was too difficult
    or because Florida failed to satisfy the “threshold” re­
    dressability requirement for Article III standing. And
    even if the Special Master did apply the wrong standard,
    his misstep would not justify a remand because his find­
    ings are plainly correct and establish that Georgia should
    prevail under the balance-of-harms test.
    Cite as: 585 U. S. ____ (2018)           15
    THOMAS, J., dissenting
    1
    The Special Master applied the balance-of-harms test
    from this Court’s precedents. A State seeking an equitable
    apportionment that interferes with established uses must
    “demonstrat[e] by clear and convincing evidence that the
    benefits of the [apportionment] substantially outweigh the
    harm that might result.” Colorado 
    I, 459 U.S., at 187
    ;
    accord, Colorado 
    II, supra, at 316
    –317. This heavy burden
    reflects the need for “judicial caution” before granting
    equitable apportionments, which “involve the interests of
    quasi-sovereigns, present complicated and delicate ques­
    tions, and . . . necessitate expert administration.” Colo-
    rado v. Kansas, 
    320 U.S. 383
    , 392 (1943) (Kansas II );
    accord, Colorado 
    II, 467 U.S., at 316
    (explaining that
    the clear-and-convincing-evidence burden “appropriately
    balance[s] the unique interests involved in water rights
    disputes between sovereigns”).         It also reflects “this
    Court’s long-held view that the proposed diverter should
    bear most, if not all, of the risks of erroneous decision”
    because the benefits he claims for proposed future uses are
    usually “ ‘speculative and remote’ ” while the costs of dis­
    rupting established uses are “ ‘typically certain and imme­
    diate.’ ” Ibid. (quoting Colorado 
    I, supra, at 187
    ).
    As part of the balance-of-harms analysis, this Court has
    repeatedly held that the State seeking to divert water
    from existing uses must show that it will obtain some
    appreciable benefit from an equitable apportionment. See,
    e.g., Idaho 
    I, 444 U.S., at 392
    ; New 
    Jersey, 283 U.S., at 345
    . This appreciable-benefit requirement reflects the fact
    that a minimal benefit cannot outweigh the heavy costs
    that inevitably accompany equitable-apportionment de­
    crees. See Colorado 
    I, supra, at 187
    (“[T]he equities sup­
    porting the [status quo] will usually be compelling”); Kan-
    sas 
    II, supra, at 393
    (expressing “great and serious
    caution” over granting equitable apportionments because
    they “interfer[e] with the action of a State”). Put another
    16                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    way, the Court will not “bring distress and even ruin to a
    long-established [water use] for no other or better purpose
    than to vindicate a barren right.” 
    Washington, 297 U.S., at 523
    ; see also Kansas 
    I, 206 U.S., at 109
    . (“[B]efore, at
    the instance of a sister state, [a State’s water use] is de­
    stroyed or materially interfered with, it should be clear
    that such sister state has not merely some technical right,
    but also a right with a corresponding benefit”). Such an
    action would run contrary to “the high equity that moves
    the conscience of the court in giving judgment between
    states.” 
    Washington, 297 U.S., at 523
    .
    For example, in Washington v. Oregon—a case with
    facts strikingly similar to this one—the Court refused to
    cap Oregon’s water use because it “ ‘would materially
    injure Oregon users without a compensating benefit to
    Washington users.’ ” 
    Ibid. In that case,
    Washington
    complained about “temporary dams” that Oregon residents
    had erected to irrigate their crops during “seasons of
    [water] shortage.” 
    Id., at 522.
    Removing the dams, how­
    ever, would mean that, “[d]uring the period of water
    shortage, only a small quantity of water would go by” and
    “would be quickly absorbed and lost in the deep gravel
    beneath the channel.” 
    Id., at 522–523.
    Because a cap on
    Oregon would not benefit Washington by supplying water
    when it most needed it, the Court declined to grant Wash­
    ington’s requested relief. 
    Id., at 520–523.
        The Special Master applied this appreciable-benefit
    requirement. As he explained, Florida “ha[d] not proven
    by clear and convincing evidence” that the Corps would
    release any additional water “at a time that would provide
    a material benefit to Florida (i.e., during dry periods).”
    Report 47; see also 
    id., at 47–48
    (“[T]he Corps’ operation[s]
    . . . rende[r] any potential benefit to Florida from in­
    creased streamflow in the Flint River uncertain and spec­
    ulative”). The Special Master likewise found “an absence
    of any significant benefit to Florida” during nondrought
    Cite as: 585 U. S. ____ (2018)           17
    THOMAS, J., dissenting
    conditions. 
    Id., at 65;
    see also 
    id., at 69
    (“Florida has not
    shown that it would benefit from increased pass-through
    operations under normal conditions”); 
    id., at 62–63
    (“[T]he
    potential benefits to Florida of increased flows . . . when
    the Corps is not in drought operations are uncertain,
    rendering the efficacy of any relief speculative”). Tellingly,
    the Special Master relied exclusively on this Court’s prec­
    edents applying the appreciable-benefit requirement. See
    
    id., at 2
    4 (citing, inter alia, Idaho 
    I, supra, at 392
    ; Wash-
    
    ington, supra, at 523
    ); Report 30 (same); 
    id., at 2
    7 (citing
    New 
    Jersey, supra, at 345
    ; Colorado 
    I, supra, at 187
    ). And
    Florida agreed that it had to present proof of some benefit.
    See, e.g., Florida’s Post-Trial Response Brief 63 (conceding
    that it had to “prove that additional flows from a . . . re­
    duction in Georgia’s consumption will result in meaningful
    benefits to the Bay and River”). In short, the Special
    Master correctly applied our precedents and required
    Florida to show that it would obtain some appreciable
    benefit from an equitable-apportionment decree.
    2
    The Court does not disagree that Florida failed to prove
    an appreciable benefit. Instead, it simply asserts that a
    decision on that question is “premature.” Ante, at 8. It is
    incredibly odd to conclude that a Special Master’s merits
    determination is “premature” after a full trial. The Court
    can draw that strange conclusion only by conflating the
    rules that govern our equitable-apportionment jurispru­
    dence and then faulting the Special Master for misapply­
    ing two rules that he never applied.
    The Court criticizes the Special Master for applying “too
    strict a standard” when deciding the “ ‘threshold’ ” question
    whether the Court would be “able to fashion an appropri­
    ate equitable decree.” Ante, at 15. Although the Court’s
    reasoning is far from clear, it appears to mean one of two
    things. The Court either means that the Special Master
    18                   FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    erred by denying relief on the ground that it was too diffi­
    cult to calculate the appropriate apportionment—the
    fourth rule mentioned above. Or, the Court means that
    the Special Master erred by denying relief on the ground
    that Florida could not prove Article III standing—the first
    rule mentioned above. But the Special Master did not
    deny relief for either of these two reasons.
    a
    Both the Court and Florida suggest that the Special
    Master contravened this Court’s statement in Idaho II
    that “ ‘[u]ncertainties about the future . . . do not provide a
    basis for declining to fashion a decree.’ ” Ante, at 11–12, 35
    (quoting Idaho 
    II, 462 U.S., at 1026
    ); see also ante, at 13,
    18 (suggesting that the Special Master violated Idaho II
    by concluding that “ ‘the formulation of a workable decree
    is impossible’ ”); Brief for Plaintiff 30–31. But the Special
    Master nowhere contradicted this rule.
    The rule from Idaho II is a rule about fashioning an
    appropriate remedy when the complaining State has
    prevailed on the merits. In Idaho II, the Special Master
    concluded that he could not determine Idaho’s entitlement
    to fish “for any past or future year” because “several un­
    known variables” made it too difficult to decide how many
    fish would be available to harvest at any given time.
    Special Master’s Report, O. T. 1982, No. 67, Orig., p. 30.
    The Special Master rejected Idaho’s proposed formula for
    calculating its entitlement because he could not under­
    stand the predictive models or mathematics involved in
    applying it. 
    Id., at 40–42.
    Before this Court, Idaho objected
    to the Special Master’s conclusion, arguing that its
    proposed formula relied on procedures “that are either
    being currently employed by defendants or which involve
    simple mathematical computations.” Brief for Plaintiffs in
    O. T. 1982, No. 67, Orig., p. 82. The Court accepted Ida­
    ho’s argument, noting that a decree need not “always be
    Cite as: 585 U. S. ____ (2018)           19
    THOMAS, J., dissenting
    mathematically precise or based on definite present and
    future conditions” and that “Idaho’s proposed formula for
    apportioning the fish is one possible basis for a decree.”
    Idaho 
    II, 462 U.S., at 1026
    . “Uncertainties about the
    future,” the Court explained, “do not provide a basis for
    declining to fashion a decree.” 
    Ibid. Unlike the Special
    Master in Idaho II, the Special Mas­
    ter in this case did not conclude that it was too difficult to
    calculate the amount of water that Florida should receive.
    As the Court acknowledges, ante, at 23, the Special Master
    assumed it was feasible to impose Florida’s requested cap
    on Georgia’s water use and “accept[ed] Florida’s estimates
    of the increased streamflow that would result from a
    consumption cap.” Report 67, n. 43; see 
    id., at 34
    –35. But
    even if a cap on Georgia generated the additional water
    that Florida claimed it would (1,500 to 2,000 cubic feet per
    second), the Special Master concluded that it would not
    appreciably benefit Florida because it would not be passed
    through when Florida needed it. See 
    id., at 47–48
    , 62–65,
    69. That is why the Special Master cited the appreciable-
    benefit rule from Idaho 
    I, 444 U.S., at 392
    , and Washing-
    
    ton, 297 U.S., at 523
    . He did not fail to make reasonable
    predictions in shaping a remedy or otherwise contravene
    the rule from Idaho II.
    b
    Florida alternatively contends that the Special Master
    applied the “redressability” requirement of Article III
    standing. See Brief for Plaintiff 29–32. At some points,
    the Court appears to agree with this characterization, as it
    describes the appreciable-benefit rule as an Article III
    standing requirement. See ante, at 13 (quoting the Article
    III standing rule from Wyoming v. 
    Oklahoma, 502 U.S., at 447
    , 452, Maryland v. 
    Louisiana, 451 U.S., at 735
    –736,
    and Massachusetts v. Missouri, 
    308 U.S. 1
    , 15 (1939), and
    describing the appreciable-benefit rule from Kansas I and
    20                      FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    Washington as a “[m]ore specifi[c]” articulation of that
    rule). This argument is incorrect.
    As explained, the Special Master applied the ordinary
    balance-of-harms analysis and found that Florida had not
    demonstrated an appreciable benefit from a cap on Geor­
    gia’s use. Tellingly, the Special Master relied exclusively
    on cases conducting the balance-of-harms analysis. His
    Report does not cite any standing cases, or even mention
    “standing” or “Article III.” Neither do any of the pre-trial
    or post-trial briefs that the parties filed. True, the Special
    Master’s Report sometimes describes the appreciable-
    benefit requirement as a question of “redressability”—a
    word that is also associated with Article III standing. But
    the Special Master was merely following the parties’ lead,
    as they phrased the appreciable-benefit requirement in
    terms of “redress” throughout the litigation. See Tr. of
    Oral Arg. on Motion to Dismiss 29 (Florida admitting that
    it must show “that caps on consumption will . . . redress
    [its] harms” to “prov[e] its case”); Florida Pre-Trial Brief
    37–39 (describing how a consumption cap “can redress
    Florida’s worsening injuries” and “significantly benefit
    Florida’s ecology”); Georgia Post-Trial Brief 80–88 (de­
    scribing the appreciable-benefit aspect of the balance-of­
    harms test as a “redress” requirement); Georgia’s Post-
    Trial Response Brief 3, 7 (same); see also United States
    Post-Trial Brief 19 (taking no position “on whether Florida
    has proved that a consumption cap would produce enough
    additional [B]asin inflow at the right times to redress
    Florida’s alleged harm and justify the cost of imposing a
    consumption cap” (emphasis added)). That the parties and
    the Special Master adopted this shorthand does not
    change the Special Master’s analysis, which focused
    squarely on the appreciable-benefit requirement.6
    ——————
    6 The Court places great weight on the fact that the Special Master
    referred to redressability as a “threshold” requirement. See ante, at 8–
    Cite as: 585 U. S. ____ (2018)                     21
    THOMAS, J., dissenting
    c
    Because the Court wrongly assumes that the Special
    Master denied relief on the basis rejected in Idaho II or for
    lack of Article III standing, it faults the Special Master for
    imposing the higher burden of proof that governs the
    merits—i.e., “clear and convincing evidence.” See ante, at
    15–18.7 Of course, the far simpler explanation for why the
    Special Master applied the merits standard is that he was,
    in fact, making a decision about the merits, not about
    remedies or standing.
    The Court also appears to fault the Special Master for
    addressing the appreciable-benefit requirement without
    first making several preliminary findings. The Court
    asserts that Special Masters must make specific factual
    determinations in every case about the harm that the
    complaining State suffered, the exact amount of water
    needed to remedy that harm, and a host of other factors.
    See ante, at 13–17.
    The Court’s suggested order of operations, which it
    appears to invent out of thin air, would fundamentally
    transform our equitable-apportionment jurisprudence. It
    ——————
    9, 15, 19. But showing an appreciable benefit is a “threshold” require­
    ment for prevailing under the balance-of-harms test, as a State that
    cannot show an appreciable benefit obviously cannot show that the
    balance of harms tilts in its favor. In other words, the Court need not
    engage in a full-scale balancing of benefits and harms if the party that
    bears the burden of proof has nothing to place on its side of the scale; it
    can reject that type of case at the “threshold.” That the Special Master
    used the word “threshold” does not suggest that he was doing anything
    other than applying the ordinary balance-of-harms test.
    7 In faulting the Special Master for requiring clear and convincing
    evidence, the Court combines the rule from Idaho II with the balance-
    of-harms test from Kansas I, Washington, and Idaho I. See ante, at 18.
    The Court reconciles these precedents as follows: “[T]hese [cases] apply
    to the general availability of judicial relief—not to the details of a final
    decree or to the workability of a decree that will depend on those
    details.” 
    Ibid. I do not
    understand this sentence, and I pity the liti­
    gants and Special Masters who will be forced to decipher it.
    22                   FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    will require States to litigate (and this Court to resolve) a
    host of complex factual questions, even where the State
    seeking the apportionment is obviously not entitled to
    relief because it cannot show an appreciable benefit—a
    requirement that Florida agrees is necessary for it to
    prevail, see Florida Post-Trial Response Brief 63 (agreeing
    it must “prove that additional flows from a . . . reduction
    in Georgia’s consumption will result in meaningful bene­
    fits to the Bay and River”); Tr. of Oral Arg. on Motion to
    Dismiss 29 (admitting it must show “that caps on con­
    sumption will . . . redress [its] harms” to “prov[e] its case”).
    In no other area of the law do we require unnecessary
    findings and conclusions when a key element of the plain­
    tiff ’s case is missing. And we have not applied this rule in
    equitable apportionment cases either. See, e.g., Idaho 
    II, 462 U.S., at 1027
    –1029 (denying relief, despite the Spe­
    cial Master’s erroneous ruling on the requested remedy,
    because his findings also supported the conclusion that
    Idaho could not show injury and thus was not entitled to
    relief on the merits). The inefficiencies that this would
    create, and the costs it would impose on States, are obvi­
    ous. Yet the Court faults the Special Master for resolving
    the dispositive question in this case first, without jumping
    through a series of unnecessary hoops. This is precisely
    the opposite of what Special Masters should be doing and
    what this Court should be encouraging.
    3
    Even if the Court is correct that the Special Master
    denied Florida relief for some reason other than the mer­
    its, there is no reason to send this case back for a do-over.
    As the Court acknowledges, “ ‘the ultimate responsibility
    for deciding what are correct findings of fact remains with
    us.’ ” Ante, at 18–19 (Colorado 
    II, supra, at 317
    ). We
    “must bring our independent judgment to bear based upon
    ‘our own independent examination of the record.’ ” Kansas
    Cite as: 585 U. S. ____ (2018)                   23
    THOMAS, J., dissenting
    v. Missouri, 
    322 U.S. 213
    , 232 (1944). An independent
    examination of the record confirms that the Special Mas­
    ter was correct to find that the Corps would not change its
    operations during droughts if this Court capped Georgia’s
    water use and thus Florida would not benefit from a cap
    during droughts. See Part IV–B–1, infra. The Special
    Master also was correct to find that Florida presented no
    evidence of a benefit during nondroughts. See Part IV–B–
    2, infra. Those findings support a judgment in Georgia’s
    favor under the traditional balance-of-harms analysis.
    It makes little sense to send this case back to the Spe­
    cial Master so that he can amend his Report to say “appre­
    ciable benefit” instead of “redress” and then send this case
    right back to this Court.8 That pointless exercise will only
    needlessly prolong this litigation. The Court’s subtle
    suggestion that Florida could present “additional evi­
    dence” on remand, ante, at 36, is not a satisfactory re­
    sponse. During their 18 months of discovery, the parties
    produced 7.2 million pages of documents, served 130 third-
    party subpoenas, issued more than 30 expert reports, and
    conducted nearly 100 depositions, including 29 expert
    depositions. Florida thus had a more-than-ample oppor­
    tunity to gather its evidence and then present it at a 1­
    month trial. Giving Florida another bite at the apple will
    likely yield no additional evidence, but it will be unfair to
    Georgia, which has already spent the time and resources
    to defeat the case that Florida chose to present. In short,
    we have all the evidence we need to decide this case now.
    ——————
    8 The Court concedes that Florida cannot prevail in this case unless it
    proves, by clear and convincing evidence, that it would obtain an
    appreciable benefit from an equitable apportionment. See ante, at 18
    (noting that the appreciable benefit test “ ‘goes to the merits’ of the
    equitable apportionment inquiry”); ante, at 19 (noting “a remand is
    necessary to conduct the equitable-balancing inquiry”); ante, at 36
    (noting that Florida must ultimately prevail in the balance of harms
    test).
    24                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    We should have done so.
    B
    Florida’s second and third objections—which challenge
    the Special Master’s finding that Florida had not met its
    burden under the balance-of-harms test—also fail. As
    explained, a State seeking to interfere with established
    uses must prove its case by clear and convincing evi­
    dence—a “much greater” burden than the one normally
    imposed in civil cases. 
    Connecticut, 282 U.S., at 669
    . To
    meet this burden, Florida must present enough evidence
    to leave this Court with an “abiding conviction that the
    truth of its factual contentions are ‘highly probable’ ” and
    to “instantly til[t] the evidentiary scales in the affirmative
    when weighed against the evidence . . . offered in opposi­
    tion.” Colorado 
    II, supra, at 316
    . As the Special Master
    found, Florida has not met this burden. The evidence
    demonstrates that, if this Court imposed Florida’s pro­
    posed cap on Georgia, Florida would not receive an appre­
    ciable amount of additional water during droughts. And
    Florida would not benefit from the additional water that it
    received during nondroughts.
    1
    Florida did not demonstrate that, if this Court caps
    Georgia’s water use, Florida would receive a meaningful
    amount of additional water during droughts. For Florida
    to receive more water, the Corps must change its current
    operating procedures. But the Corps is not a party, and it
    would not be bound by any decree issued by this Court.
    Because Florida cannot ask this Court to require the
    Corps to change its existing operations, it must prove by
    clear and convincing evidence that the Corps will volun­
    tarily make the necessary changes. Florida cannot do so.
    The United States’ representations in this litigation and
    the Corps’ history and practice in the Basin all reveal that
    Cite as: 585 U. S. ____ (2018)          25
    THOMAS, J., dissenting
    the Corps will not change its existing practices, even if
    this Court caps Georgia’s water use.
    Throughout this litigation, the United States has con­
    sistently maintained that the Corps “would not generally
    expect” to release more water into Florida during
    droughts, even if Florida convinced this Court to cap
    Georgia’s use. Brief for United States 28; see also United
    States Post-Trial Brief 17–18 (“The Corps expects [during
    drought operations] that Apalachicola River flows would
    be very similar with or without a consumption cap until
    enough water is stored to return the system to normal
    operations”). This is because “[B]asin inflow . . . has his­
    torically not been the primary factor in the Corps’ deci­
    sionmaking process for making additional releases above
    5[,]000 [cubic feet per second] during drought operations.”
    Brief for United States 28. The Corps’ “overriding” priori­
    ties during droughts are preserving enough water “to
    comply with the [Endangered Species Act] while avoiding
    catastrophic depletion of storage and refilling [its] reser­
    voirs as rapidly as possible.” 
    Id., at 27.
    Deviations are
    made only “as needed to serve congressionally authorized
    project purposes” or “in emergency circumstances.” 
    Ibid. Since a general
    need to provide more water to Florida does
    not fall within either exception, the additional water that
    would flow into the Basin would not translate into addi­
    tional flows for Florida. See 
    id., at 2
    9.
    The United States’ representations are consistent with
    the Corps’ historical practice.       During droughts, the
    amount of water entering the Basin is almost always
    insufficient to meet the Corps’ minimum-flow requirement
    of 5,000 cubic feet per second. See Bedient 24–27. Thus, a
    cap on Georgia would simply decrease the amount of water
    that the Corps must release from storage; it would not
    increase the amount of water flowing into the Apalachicola
    River. 
    Id., at 21,
    25–26. And once drought operations are
    triggered, the Corps limits its releases to around 5,000
    26                     FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    cubic feet per second regardless of the amount of water
    entering the Basin. See United States Post-Trial Brief 9;
    Brief for United States 24–28. Indeed, during past
    drought operations, even when Basin inflow varied by tens
    of thousands of cubic feet per second, the measured flow
    from Jim Woodruff Dam into the Apalachicola River has
    consistently remained around 5,000 cubic feet per second.
    See Bedient 23, 62–63.9 Further, the models presented by
    Georgia’s expert showed that, if Florida’s proposed caps
    had been in place during the drought years of 2007 and
    2012, Florida would not have received appreciable addi­
    tional flows when the water was most needed. Cutting
    Georgia’s use in half would have produced additional flows
    for only 14 to 19 days in the summer and fall of 2007, and
    would not have produced any additional flows during the
    summer or fall of 2012. 
    Id., at 27–30;
    see also 
    id., at 38
    (showing the same for 2011).
    Florida argues that the Corps might exercise its discre­
    tion to ensure that additional water reaches Florida dur­
    ing droughts. Brief for Plaintiff 40–44. But Florida sup­
    ports this claim with nothing more than speculation. See
    Colorado 
    II, 467 U.S., at 320
    (explaining that a State
    cannot carry its burden in an equitable-apportionment
    action except “with specific evidence” and that “[m]ere
    assertions . . . will not do”). All available evidence sug­
    gests that the Corps would not exercise its discretion to
    release more water into the Apalachicola River during
    droughts.
    Before this Court, the United States expressly rejected
    ——————
    9 It makes no difference whether the additional water generated by a
    cap on Georgia would enter the Flint River. Contra, Brief for Plaintiff
    26, 38–39. If additional water entered the Flint River during droughts,
    the Corps would release less water from its upstream reservoirs on the
    Chattahoochee River to maintain a consistent flow of around 5,000
    cubic feet per second from the Jim Woodruff Dam at Lake Seminole.
    See Bedient 24–26; Brief for United States 24–25.
    Cite as: 585 U. S. ____ (2018)            27
    THOMAS, J., dissenting
    Florida’s contention that “the Corps is likely to exercise its
    authority within existing operational protocols to provide
    Florida with additional flows produced by a cap on Geor­
    gia’s consumption.” Brief for United States 23. Basin
    inflows, it explained, simply do not dictate how much
    water the Corps releases into the Apalachicola River.
    
    Ibid. And the Corps
    could not make discretionary releases
    “that [are] not specifically provided for in the [water­
    control manual], not specifically authorized by Congress or
    mandated by general statute, [and not] required by a court
    order directed to the Corps,” without raising “significant
    and difficult question[s]” about whether it had exceeded
    its authority. 
    Id., at 29.
       Florida also suggests that the Corps might amend its
    water-control manual in response to an equitable decree
    from this Court. Florida’s only support for this argument
    is a statement from the Corps that it will “ ‘take . . . into
    account’ ” this Court’s decision. Brief for Plaintiff 44 (quot­
    ing Record of Decision Adopting Proposed Action Alterna­
    tive for Implementation of Updated Apalachicola­
    Chattahoochee-Flint River Basin Master Manual 18 (Mar.
    30, 2017)). But this vague statement was not a promise
    that the Corps will change its procedures, and there are a
    host of reasons to doubt that the Corps would voluntarily
    change its procedures just because this Court capped
    Georgia’s use.
    For one, the Corps has already tried procedures that
    passed more water to Florida during droughts. The re­
    sults were dreadful: Reservoir storage plummeted to
    dangerously low levels, putting all of the Corps’ authorized
    project purposes at risk. Zeng 45–46. Since that time, the
    Corps’ operating protocols have become increasingly pro­
    tective of reservoir storage, particularly during droughts.
    As the Corps explained, it intends to pursue “ ‘a more
    proactive approach to conserve reservoir storage as drier
    conditions develop in the [B]asin’ ” because the “[s]torage
    28                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    of water during drought operations is critically important
    to retain sufficient water in the system.” Brief for United
    States 11.
    For another, the last time the Corps attempted to
    change its water-control manual, it required more than
    two decades of litigation and administrative review to
    finalize those changes. Indeed, the main reason that the
    United States chose not to participate in this case is be­
    cause it wanted “to avoid being bound by a decree that
    could directly affect the Corps operations before the Corps
    had a chance to finally complete its process of updating
    the [water-control manual].” 
    Id., at 32.
    Given this, there
    is no reason to think that the Corps will volunteer to
    undertake the process of updating its manual again—
    especially so soon after it completed this arduous task.
    Florida’s speculation is even more suspect in view of the
    changes that the Corps would have to make to benefit
    Florida during droughts. To even propose a new water-
    control manual, the Corps must “examin[e] . . . the con­
    gressionally authorized purposes,” “determin[e] . . . how
    providing additional flows will impact those purposes
    [and] other laws,” and “supplemen[t] documentation of
    environmental impacts as required by [the National Envi­
    ronmental Policy Act].” 
    Id., at 31.
    Providing more water
    to Florida does not help the Corps satisfy any of these
    legal requirements. It is not one of the congressionally
    authorized purposes, see 
    id., at 2
    9, 31–32, and, by drop­
    ping its lawsuit against the Corps, Florida now accepts
    that a minimum flow of 5,000 cubic feet per second is
    sufficient to comply with the Endangered Species Act.
    Florida cannot claim that the law requires the Corps to
    provide it with more water. And the idea that the Corps
    will change its operating protocols to serve an unauthor­
    ized purpose when doing so could jeopardize its authorized
    purposes is simply not plausible.
    Taking a different tack, the Court suggests that addi­
    Cite as: 585 U. S. ____ (2018)                  29
    THOMAS, J., dissenting
    tional water will pass through to Florida even if the Corps
    does not change its manual. Specifically, the Court con­
    cludes that the additional water will pass through to
    Florida during droughts so long as the Corps does not
    enter drought operations. See ante, at 25–27. According
    to the Court, the Corps will allow additional water to pass
    through to Florida whenever the natural flow of the
    Apalachicola River is between 5,000 and 10,000 cubic feet
    per second during normal or “nondrought” operations. See
    ante, at 25–26.
    The Court’s conclusion depends on the premise that,
    during droughts, the natural streamflow into Florida is
    “between 5,000 and 10,000” cubic feet per second. 
    Ibid. That premise is
    false.10 During droughts, the natural
    streamflow in the Apalachicola River is usually less than
    5,000 cubic feet per second. Supra, at 25; see also Bedient
    23 (showing that Basin inflow in 2012 was generally below
    ——————
    10 The Court contends that I have confused “droughts” and “drought
    operations.” See ante, at 29–30. I have not, but the Court has. During
    droughts—periods in which there is a “lack of rain,” 4 Oxford English
    Dictionary 1076 (2d ed. 1989)—the amount of water that naturally
    flows into the Basin rivers usually falls below 5,000 cubic feet per
    second, particularly in the summer and fall months. See infra, at 29–
    31. Since the Corps must ensure that the Apalachicola River always
    receives at least 5,000 cubic feet per second, the Corps augments the
    natural streamflow during droughts—even when the Corps is not in
    drought operations. Bedient 21. Thus, any additional water that a cap
    on Georgia generates during droughts would only increase streamflow
    into the Apalachicola River if it caused the natural streamflow to
    exceed 5,000 cubic feet per second. If the additional water increased
    streamflow to some amount less than that, then it would not increase
    flows in the Apalachicola River; it would simply decrease the amount of
    water that the Corps must release from its reservoirs. See 
    ibid. Thus, as Georgia’s
    expert explained, “reducing Georgia’s consumptive use
    would only lead to additional . . . flow into Florida under specific and
    limited circumstances. First, the Corps cannot be in Drought Opera­
    tions or [Extreme Drought Operations]. Second, Basin Inflow cannot be
    below 5,000 [cubic feet per second], even if the Corps is in normal
    operations.” 
    Id., at 26
    (emphasis added).
    30                     FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    5,000 cubic feet per second between June and December);
    
    id., at 2
    7 (same for 2007). To maintain a minimum flow of
    5,000 cubic feet per second during droughts, the Corps
    must artificially augment the River’s natural flow—even
    when the Corps is in nondrought operations. 
    Id., at 21.
    11
    For instance, during the 2011 drought (when the Corps
    was in nondrought operations), “Basin Inflow was below
    5,000 [cubic feet per second] for most of th[e] period [be­
    tween June and December], and the Corps was ‘augment­
    ing’ streamflow by releasing water from the reservoirs to
    satisfy the 5,000 [cubic feet per second] minimum.” 
    Id., at 15;
    see also 
    id., at 2
    7 (same for 2007). Once the Corps
    adds enough water to reach 5,000 cubic feet per second,
    however, it generally adds no more than that. 
    Id., at 21.
    To give a concrete example, if the natural flows in the
    Apalachicola River were 2,600 cubic feet per second, then
    the Corps would release 2,400 cubic feet per second from
    its reservoirs. See 
    id., at 2
    5–26. And if a cap on Georgia
    increased the River’s natural flow to 4,100 cubic feet per
    second, the Corps would release 900 cubic feet per second.
    See 
    ibid. In either case,
    the total flow on the Apalachicola
    River would remain the same: 5,000 cubic feet per second.
    Thus, so long as the natural flows remain significantly
    ——————
    11 The Court contends that additional water from a cap on Georgia
    likely would have passed through to Florida in the summer of 2009.
    See ante, at 26–27. But this evidence is irrelevant. As Florida’s own
    expert testified, “[t]he year 2009 was a relatively wet year.” Horn­
    berger 49; accord, Bedient 45. And Florida has only asked this Court to
    reduce Georgia’s consumption by 1,500 to 2,000 cubic feet per second
    during “severe drought years,” which 2009 was not. Hornberger 58.
    The Court also contends that additional water from a cap on Georgia
    likely would have passed through to Florida in the summers of 2016
    and 2017. See ante, at 26–27, 32. The Court’s data was generated
    simultaneously with or after most of the testimony in this case, so the
    experts do not speak to it. But even considering the data that the
    Court has found, I suspect that 2016 and 2017 are not “severe drought
    years” either and, thus, are irrelevant.
    Cite as: 585 U. S. ____ (2018)                   31
    THOMAS, J., dissenting
    less than 5,000 cubic feet per second, a cap on Georgia
    would only decrease the amount of water that the Corps
    releases from storage; it would not increase the overall
    amount of water flowing into the Apalachicola River.
    For this reason, even when the Corps is in nondrought
    operations, a cap on Georgia would generally not increase
    flows to Florida. Georgia’s expert proved that fact with
    evidence about past droughts where drought operations
    were not in effect. Using data from the 2007 drought,
    Georgia’s expert concluded that the additional water from
    a cap on Georgia would be passed through to Florida
    almost entirely during the winter and spring months
    “when water in the [Basin] would be relatively plentiful.”
    
    Id., at 28.
    Florida would receive the additional water from
    a cap on Georgia only 19 days “during the summer and fall
    months, when streamflow was at its lowest.” Ibid.; accord,
    
    id., at 40.
    Data from the 2011 drought showed similar
    results. See 
    id., at 37
    (“[During] dry years (e.g., 2007 and
    2011), . . . even significant changes in Georgia’s consump­
    tive use would lead to virtually no change in state-line
    flows during the low-flow months (e.g., June, July, August,
    September)”).12 Florida has not shown that these infre­
    quent and sporadic additional flows during droughts
    would appreciably benefit it.13
    ——————
    12 The Court claims that “Florida’s proposed consumption cap . . . will
    mean (consistent with the testimony of the very Georgia expert that the
    dissent so frequently quotes) that there will be significantly fewer such
    days [of drought operations].” Ante, at 30. I assume that the “Georgia
    expert” in this sentence is Dr. Philip Bedient. But I am aware of no
    testimony from Dr. Bedient that supports the Court’s assertion, and the
    Court cites none.
    13 If the Corps had been in drought operations, the results would not
    have differed much, demonstrating that whether the Corps is in
    drought or nondrought operations is not dispositive. Had the Corps
    been in drought operations during 2007, for instance, Florida would
    have received the additional water from a cap on Georgia during 14
    days in the summer and fall—a difference of only five days as compared
    32                     FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    The Court hypothesizes that a cap on Georgia could
    benefit Florida by decreasing the length of drought opera­
    tions and by increasing the number of days that the Corps
    can meet its minimum-flow requirements of 5,000 cubic
    feet per second (during normal drought operations) and
    4,500 cubic feet per second (during extreme drought oper­
    ations). Ante, at 24, 27–29. The Court cites the United
    States’ assertion in its brief that increased Basin inflows
    “ ‘would generally benefit the [Basin] system by delaying
    the onset of drought operations, by allowing the Corps to
    meet the 5000 [cubic feet per second] minimum flow longer
    during extended drought, and by quickening the resump­
    tion of normal operations.’ ” Ante, at 24 (quoting Brief for
    United States 28); see also ante, at 28 (quoting a similar
    statement in the United States Post-Trial Brief 18–19). Of
    course, statements in briefs are not evidence. And, as the
    United States recognizes in the very next sentence, Flor-
    ida would have to show that these “benefits are of suffi­
    cient quantity to justify relief in this case.” Brief for United
    States as Amicus Curiae 28 (Aug. 7, 2017); see also
    United States Post-Trial Brief 19 (Dec. 15, 2016) (taking
    “no position on whether Florida has proven that a con­
    sumption cap would produce enough additional [B]asin
    inflow at the right times to redress Florida’s alleged harm
    and justify the cost of imposing a consumption cap”).
    Florida offered no proof that a cap on Georgia would
    produce any appreciable benefit of this kind. And the
    evidence presented at trial suggests that these proposed
    benefits are wholly speculative. As explained above, the
    benefits to Florida from a cap on Georgia do not meaning­
    fully change, regardless of whether the Corps enters
    drought operations. And there is no evidence that the
    Corps has had trouble meeting its minimum flow require­
    ments during recent droughts, when Georgia’s use re­
    ——————
    to nondrought operations. Bedient 28.
    Cite as: 585 U. S. ____ (2018)           33
    THOMAS, J., dissenting
    mained uncapped. Even during the severe droughts of
    2011 and 2012, the Corps consistently maintained flows of
    5,000 cubic feet per second, never entered extreme
    drought operations, and never reduced flows on the Apa­
    lachicola River to 4,500 cubic feet per second. See Bedient
    14. And the Corps is even more unlikely to run out of
    water during future droughts, given that its current man­
    ual is more proactive in conserving water during droughts.
    See Brief for United States 11–12.
    In sum, Florida has not shown that it is “ ‘highly proba­
    ble’ ” that a cap on Georgia will result in meaningful addi­
    tional flows in the Apalachicola River during droughts.
    Colorado 
    II, 467 U.S., at 316
    . It is thus not entitled to an
    equitable apportionment on this basis.
    2
    Because Florida will not receive additional water during
    droughts, it argues that it will benefit from additional
    water during nondroughts. As the Special Master correctly
    found, however, Florida presented no evidence to support
    such an assertion. That is because no such evidence ex­
    ists. Florida would not benefit from additional water
    during nondroughts, because flows on the Apalachicola
    River during nondroughts are already plentiful.
    The Court does not contend that Florida would benefit
    from additional water during nondroughts, and Florida all
    but conceded the point below. When framing its case
    before the Special Master, Florida requested only that the
    Court order Georgia to reduce its water use during
    droughts; Florida did not ask the Court to reduce Geor­
    gia’s current water use during nondroughts. See Florida
    Pre-trial Brief 5; Hornberger 58. Consistent with this
    request, Florida’s evidence focused exclusively on the
    harms that it suffered during droughts. Florida’s hydrol­
    ogy expert testified extensively about droughts. See 
    id., at 2
    –3, 15–26, 41–46, 49–50. He testified that the Basin
    34                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    usually receives “a rather good amount of a rainfall,” so
    “major problems arise” only during “the low rainfall
    years.” 
    Id., at 13.
    That is why he limited his testimony to
    the “impacts of [Georgia’s] consumption during drought.”
    
    Id., at 15;
    see also 
    id., at 2
    0–22.
    Florida’s other experts followed this drought-centric
    approach. For instance, one of Florida’s experts on the
    harm to Florida’s oysters connected that harm to “severe
    drought,” which “reduced the discharge of fresh water
    from the Apalachicola River.” Updated PFDT of David
    Kimbro 14. Florida’s expert on the harm to sturgeon,
    mussels, and tupelo trees in the Apalachicola River simi­
    larly emphasized “dry periods of episodically dry years.”
    Allan 17; see also 
    id., at 2
    5–27 (emphasizing the effects of
    sustained flows below 6,000 cubic feet per second). As one
    Florida expert put it, “[t]he discussions that [he] had,
    especially with the biologists and the hydrologists, were
    largely almost exclusively focused on dry years” and he
    “c[ould]n’t think of any” “issues [that] other experts raised
    about average or wet-year problems.” 11 Trial Tr. 2811.
    The other evidence presented at trial leaves little doubt
    that Florida would not benefit from additional water
    during nondroughts. For starters, when the Basin is not
    experiencing a drought, water is plentiful. Florida’s ex­
    pert testified that “[a]verage rainfall in the portion of the
    . . . Basin above [Lake Seminole] is 51.5 inches per year, a
    rather good amount of a rainfall.” Hornberger 13. As a
    result, average monthly flows in the Apalachicola River
    are nearly 20,000 cubic feet per second. Direct Testimony
    of Sorab Panday 30 (Panday). More than 95% of the time,
    Apalachicola River flows exceed 6,000 cubic feet per sec­
    ond. Brief for Unites States 12. And it is not unusual for
    flows in the Apalachicola River to exceed 50,000 cubic feet
    per second in the wetter months. See Panday 30. Even
    during drought years, flows in nonsummer months are
    relatively high. For instance, in the severe drought year of
    Cite as: 585 U. S. ____ (2018)          35
    THOMAS, J., dissenting
    2012, flow in the late winter and early spring regularly
    exceeded 10,000 cubic feet per second. See Bedient 29.
    Almost all of the additional water generated by a cap on
    Georgia would reach Florida during these high flow peri­
    ods, when it would provide no benefit to Florida. See 
    id., at 2
    7–30. Take, for instance, the oysters in Apalachicola
    Bay—the only harm to Florida that the Special Master
    found in this case. See Report 31–32. Florida’s own ex­
    perts testified that, even if Georgia cut its agricultural
    water use in half during droughts, the resulting increase
    in Apalachicola River flows would have a negligible effect
    during nondroughts. During years of normal rainfall and
    the wetter months of drought years, the effect of additional
    flows on the Bay’s salinity is less than one part per thou­
    sand. See 7 Trial Tr. 1768–1775. This immeasurable
    effect on the Bay’s salinity would have no appreciable
    impact on oyster biomass. See White 50–51 (showing a
    less than 0.6% impact on oyster biomass, except in drier
    months and drought years).
    Assuming Florida’s claims of harm to mussels, sturgeon,
    and tupelo trees have merit—something the Special Mas­
    ter never found—the harm to those species also would not
    be remedied by increased flows during nondroughts.
    Florida’s expert on these species opined that significant
    harm to mussels occurs when flows drop below a threshold
    of 6,000 cubic feet per second for more than seven consecu­
    tive days between June 1 and September 30, Allan 33;
    that significant harm to sturgeons occurs when flows drop
    below a threshold of 7,000 cubic feet per second for more
    than 60 total days between May 1 and September 30, 
    id., at 41;
    and that significant harm to tupelo trees occurs
    when flows drop below a threshold of 14,100 cubic feet per
    second for more than 90 consecutive days between March
    20 and September 22, 
    id., at 33
    , 41, 44–45. Accepting
    these statements as true, passing more water through to
    Florida during nondroughts would not do these species
    36                  FLORIDA v. GEORGIA
    THOMAS, J., dissenting
    any good. All would still suffer the same harms during the
    summers of drought years when flows remain fixed
    at 5,000 cubic feet per second because of the Corps’
    operations.
    If we contrast the de minimus benefits that Florida
    might receive from small amounts of additional water
    during nondroughts with the massive harms that Georgia
    would suffer if this Court cut its water use in half during
    droughts, it is clear who should prevail in this case. Flori­
    da’s expert estimated that a cap on Georgia would have an
    “[i]ncremental [f]iscal [c]ost” of $35.2 million per year.
    Sunding 44. This figure included only additional costs that
    would require “the [Georgia] legislature . . . to appropriate
    money.” 11 Trial Tr. 2791. The real cost of such a cap,
    which includes nongovernmental costs like welfare losses,
    would range anywhere from $191 million, 
    id., at 2
    787;
    Stavins 31, to more than $2 billion per year, 
    id., at 2
    . And
    the cap would trigger resulting losses in Georgia’s gross
    regional product and employment, totaling around $322
    million and 4,173 jobs annually. 
    Id., at 40.
    Regardless of
    the measure used, this harm dwarfs the value of Florida’s
    entire fishing industry in Apalachicola Bay, which pro-
    duces annual revenues of $11.7 million. 
    Id., at 16.
    And it
    greatly outweighs the value of the additional oysters that
    a cap on Georgia’s use might produce—i.e., no more than a
    few hundred thousand dollars. 
    Id., at 52.
    Imposing an
    enormously high cost on one State so that another State
    can achieve a hollow victory is “not the high equity that
    moves the conscience of the court in giving judgment
    between states.” 
    Washington, 297 U.S., at 523
    .
    *     *    *
    In the final analysis, Florida has not shown that it will
    appreciably benefit from a cap on Georgia’s water use.
    Absent such a showing, the balance of harms cannot tip in
    Florida’s favor. Accordingly, I would have overruled Flor­
    Cite as: 585 U. S. ____ (2018)         37
    THOMAS, J., dissenting
    ida’s objections to the Special Master’s Report and denied
    Florida’s request for relief. I respectfully dissent.