Florida v. Georgia

(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 2791. 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 24
(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 27
(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 24 (citing, inter alia, Idaho I, supra, at 392; Wash-
ington, supra, at 523); Report 30 (same); id., at 27 (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 29.
   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 29, 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 27 (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 27 (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 25–26. 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 20–22.
    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 25–27 (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 27–30. 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 2787;
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.