(Slip Opinion) OCTOBER TERM, 2020 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 SECOND REPORT OF SPECIAL MASTER
No. 142, Orig. Argued February 22, 2021—Decided April 1, 2021
This case involves a dispute between Florida and Georgia concerning the
proper apportionment of interstate waters. Florida brought an origi-
nal action against Georgia alleging that its upstream neighbor con-
sumes more than its fair share of water from interstate rivers in the
Apalachicola-Chattahoochee-Flint River Basin. Florida claims that
Georgia’s overconsumption of Basin waters caused low flows in the
Apalachicola River which seriously harmed Florida’s oyster fisheries
and river ecosystem. The first Special Master appointed by the Court
to assess Florida’s claims recommended dismissal of Florida’s com-
plaint. The Court disagreed with the Special Master’s analysis of the
threshold question of redressability, and remanded for the Special
Master to make definitive findings and recommendations on several
issues, including: whether Florida had proved any serious injury
caused by Georgia; the extent to which reducing Georgia’s water con-
sumption would increase Apalachicola River flows; and the extent to
which any increased Apalachicola flows would redress Florida’s inju-
ries. Florida v. Georgia, 585 U. S. ___. Following supplemental brief-
ing and oral argument, the Special Master then reviewing the case
produced an 81-page report recommending that the Court deny Florida
relief. Relevant here, the Special Master concluded that Florida failed
to prove by clear and convincing evidence that Georgia’s alleged over-
consumption caused serious harm either to Florida’s oyster fisheries
or to its river wildlife and plant life. Florida filed exceptions.
Held: Florida’s exceptions to the Special Master’s Report are overruled,
and the case is dismissed. Pp. 4–10.
(a) The Court has original jurisdiction to equitably apportion inter-
state waters between States. Given the competing sovereign interests
in such cases, a complaining State bears a burden much greater than
does a private party seeking an injunction. Florida concedes that it
2 FLORIDA v. GEORGIA
Syllabus
cannot obtain an equitable apportionment here unless it first proves
by clear and convincing evidence a serious injury caused by Georgia.
The Court conducts an independent review of the record in ruling on
Florida’s exceptions to the Special Master’s Report. Kansas v. Ne-
braska, 574 U. S. 445, 453. Pp. 4–5.
(b) Florida has not proved by clear and convincing evidence that the
collapse of its oyster fisheries was caused by Georgia’s overconsump-
tion. The oyster population in the Bay collapsed in 2012 in the midst
of a severe drought. Florida attempts to show that Georgia’s alleged
unreasonable agricultural water consumption caused reduced river
flows, which in turn increased the Bay’s salinity, which in turn at-
tracted saltwater oyster predators and disease, decimating the oyster
population. Georgia offers contrary evidence that Florida’s misman-
agement of its fisheries, rather than reduced river flows, caused the
decline. Florida’s own documents and witnesses reveal that Florida
allowed unprecedented levels of oyster harvesting in the years leading
to the collapse. And the record points to other potentially relevant fac-
tors, including actions of the U. S. Army Corps of Engineers, multiyear
droughts, and changing rainfall patterns. The precise causes of the
Bay’s oyster collapse remain a subject of scientific debate, but the rec-
ord evidence establishes at most that increased salinity and predation
contributed to the collapse of Florida’s fisheries, not that Georgia’s
overconsumption caused the increased salinity and predation. Florida
fails to establish that Georgia’s overconsumption was a substantial
factor contributing to its injury, much less the sole cause. As such the
Court need not address the causation standard applicable in equitable-
apportionment cases. Pp. 5–9.
(c) Florida also has not proved by clear and convincing evidence that
Georgia’s overconsumption has harmed river wildlife and plant life by
disconnecting tributaries, swamps, and sloughs from the Apalachicola
River, thereby drying out important habitats for river species. The
Special Master found “a complete lack of evidence” that any river spe-
cies has suffered or will suffer serious injury from Georgia’s alleged
overconsumption, Second Report of Special Master 22, and the Court
agrees with that conclusion. Pp. 9–10.
Exceptions overruled, and case dismissed.
BARRETT, J., delivered the opinion for a unanimous Court.
Cite as: 592 U. S. ____ (2021) 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
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SUPREME COURT OF THE UNITED STATES
_________________
No. 142, Orig.
_________________
STATE OF FLORIDA, PLAINTIFF v.
STATE OF GEORGIA
ON EXCEPTIONS TO SECOND REPORT OF SPECIAL MASTER
[April 1, 2021]
JUSTICE BARRETT delivered the opinion of the Court.
For the second time in three years, we confront a dispute
between Florida and Georgia over the proper apportion-
ment of interstate waters. Florida, the downstream State,
brought this original action against Georgia, claiming that
Georgia consumes more than its fair share of water from an
interstate network of rivers. Florida says that Georgia’s
overconsumption harms its economic and ecological inter-
ests, and it seeks a decree requiring Georgia to reduce its
consumption.
When the case was last before the Court, we resolved it
narrowly and remanded to a Special Master with instruc-
tions to make findings and recommendations on additional
issues. Florida v. Georgia, 585 U. S. ___ (2018). On re-
mand, the Special Master recommended that we deny Flor-
ida relief for several independent reasons, including that
Florida proved no serious injury caused by Georgia’s alleged
overconsumption.
Based on our independent review of the record, we agree
with the Special Master’s recommendation. We therefore
overrule Florida’s exceptions to the Special Master’s Report
and dismiss the case.
2 FLORIDA v. GEORGIA
Opinion of the Court
I
This case concerns the Apalachicola-Chattahoochee-Flint
River Basin, an area spanning more than 20,000 square
miles in Georgia, Florida, and Alabama. The Basin con-
tains three rivers. The Chattahoochee River and the Flint
River start in Georgia and empty into Lake Seminole,
which straddles the Georgia-Florida border. Both rivers
are critical sources of water for Georgia. The Chattahoo-
chee is the primary water supply for the Atlanta metropol-
itan area, while the Flint supplies irrigation to southwest-
ern Georgia’s agricultural industry.
The third river in the Basin is the Apalachicola River. It
starts from the southern end of Lake Seminole and flows
south through the Florida Panhandle, emptying into the
Apalachicola Bay (Bay), near the Gulf of Mexico. The
Apalachicola River supports a wide range of river wildlife
and plant life in the Florida Panhandle, and its steady sup-
ply of fresh water makes the Bay a suitable habitat for oys-
ters. For many years, Florida’s oyster fisheries were a cor-
nerstone of the regional economy.
Many factors influence Apalachicola River flows, includ-
ing precipitation, air temperature, and Georgia’s upstream
consumption of Basin waters. The U. S. Army Corps of En-
gineers also plays an important role. The Corps regulates
Apalachicola flows by storing water in, and releasing water
from, its network of reservoirs in the Basin. In recent years,
low flows in the Apalachicola River have become increas-
ingly common during the dry summer and fall months, par-
ticularly during droughts.
In 2013, on the heels of the third regional drought in just
over a decade, Florida brought this original action against
Georgia, seeking an equitable apportionment of the Basin
waters. See 28 U. S. C. §1251(a); U. S. Const., Art. III, §2.
Florida asserts that Georgia’s overconsumption of Basin
waters causes sustained low flows in the Apalachicola
Cite as: 592 U. S. ____ (2021) 3
Opinion of the Court
River, which in turn harm its oyster fisheries and river eco-
system. As a remedy, Florida seeks an order requiring
Georgia to reduce its consumption of Basin waters. Florida
does not seek relief against the Corps.
We granted Florida leave to file its complaint and re-
ferred the case to Special Master Ralph Lancaster, Jr. Af-
ter 18 months of extensive discovery and a 5-week trial, the
Special Master issued a report recommending that Florida
be denied relief. Although the Special Master assumed for
the sake of his analysis that Florida had suffered serious
injuries due to Georgia’s upstream water use, he deter-
mined that it was unnecessary to make definitive findings
on those issues because Florida failed to prove by clear and
convincing evidence that any remedy would redress its as-
serted injuries. That was so because a remedial decree
would not bind the Corps, which could operate its reservoirs
to offset any added streamflow produced by the decree.
On review of Florida’s exceptions to the Special Master’s
Report, we remanded for further proceedings. Florida v.
Georgia, 585 U. S. ___. We concluded that the Special Mas-
ter’s clear and convincing evidence standard for the
“ ‘threshold’ ” question of redressability was “too strict,” at
least absent further findings. Id., at ___–___ (slip op., at
15–16). We then directed the Special Master to make de-
finitive findings and recommendations on several addi-
tional issues, including: whether Florida had proved any se-
rious injury caused by Georgia; the extent to which
reducing Georgia’s water consumption would increase
Apalachicola River flows; and the extent to which any in-
creased Apalachicola flows would redress Florida’s injuries.
Id., at ___–___ (slip op., at 36–37).
Soon after our decision in Florida, Special Master Lan-
caster retired, and we appointed Judge Paul Kelly as the
Special Master. Following supplemental briefing and oral
argument, Special Master Kelly issued an 81-page report
recommending, for several independent reasons, that this
4 FLORIDA v. GEORGIA
Opinion of the Court
Court deny Florida relief. Relevant here, the Special Mas-
ter concluded that Florida failed to prove by clear and con-
vincing evidence that Georgia’s alleged overconsumption
caused serious harm to Florida’s oyster fisheries or its river
wildlife and plant life. Second Report of Special Master 8–
25.
Florida again filed exceptions to the Special Master’s Re-
port. We must “conduct an independent review of the rec-
ord, and assume the ultimate responsibility for deciding all
matters.” Kansas v. Nebraska, 574 U. S. 445, 453 (2015)
(internal quotation marks omitted). Having done so, we
overrule Florida’s exceptions and adopt the Special Mas-
ter’s recommendation.
II
“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.” Id., at 454. Given the weighty
and competing sovereign interests at issue in these cases,
“a complaining State must bear a burden that is ‘much
greater’ than the burden ordinarily shouldered by a private
party seeking an injunction.” Florida, 585 U. S., at ___ (slip
op., at 12).
Here, Florida must make two showings to obtain an eq-
uitable apportionment. First, Florida must prove a threat-
ened or actual injury “of serious magnitude” caused by
Georgia’s upstream water consumption. See id., at ___, ___
(slip op., at 12, 19) (internal quotation marks omitted); Col-
orado v. New Mexico, 459 U. S. 176, 187, n. 13 (1982) (Col-
orado I). Second, Florida must show that “the benefits of
the [apportionment] substantially outweigh the harm that
might result.” Id., at 187. Because Florida and Georgia are
both riparian States, the “guiding principle” of this analysis
is that both States have “an equal right to make a reasona-
ble use” of the Basin waters. Florida, 585 U. S., at ___ (slip
Cite as: 592 U. S. ____ (2021) 5
Opinion of the Court
op., at 11) (emphasis deleted; internal quotation marks
omitted).
To resolve this case, we need address only injury and cau-
sation. Florida asserts that Georgia’s overconsumption of
Basin waters caused it two distinct injuries: the collapse of
its oyster fisheries and harm to its river ecosystem. Florida
does not dispute that it must prove injury and causation by
clear and convincing evidence. See Colorado I, 459 U. S., at
187, n. 13. To do so, Florida must “place in the ultimate
factfinder an abiding conviction that the truth of its factual
contentions are ‘highly probable.’ ” Colorado v. New Mexico,
467 U. S. 310, 316 (1984) (Colorado II).
With Florida’s heavy burden in mind, we address its as-
serted injuries in turn.
A
In 2012, in the midst of a severe drought, the oyster pop-
ulation in the Apalachicola Bay collapsed, causing commer-
cial oyster sales to plummet. By the time of trial, the Bay’s
fisheries had yet to recover. All agree that this is an injury
“of serious magnitude” under our equitable-apportionment
precedents. See New York v. New Jersey, 256 U. S. 296, 309
(1921).
The parties, however, offer competing explanations for
the cause of the collapse. Florida pins the collapse on Geor-
gia through a multistep causal chain. It argues that Geor-
gia’s unreasonable agricultural water consumption caused
sustained low flows in the Apalachicola River; that these
low flows increased the Bay’s salinity; and that higher sa-
linity in the Bay attracted droves of saltwater oyster pred-
ators and disease, ultimately decimating the oyster popula-
tion.
Georgia points to a more direct cause—Florida’s misman-
agement of its oyster fisheries. According to Georgia, Flor-
ida caused the collapse by overharvesting oysters and fail-
ing to replace harvested oyster shells. And even if low flows
6 FLORIDA v. GEORGIA
Opinion of the Court
contributed at all, Georgia says, they were driven by cli-
matic changes and other factors, not its upstream consump-
tion.
Of course, the precise causes of the Bay’s oyster collapse
remain a subject of ongoing scientific debate. As judges, we
lack the expertise to settle that debate and do not purport
to do so here. Our more limited task is to evaluate the par-
ties’ arguments in light of the record evidence and Florida’s
heavy burden of proof. And on this record, we agree with
the Special Master that Florida has failed to carry its bur-
den.
Florida’s own documents and witnesses reveal that Flor-
ida allowed unprecedented levels of oyster harvesting in the
years before the collapse. In 2011 and 2012, oyster harvests
from the Bay were larger than in any other year on record.
Fla. Exh. 839; 4 Trial Tr. 956; 6 Trial Tr. 1391. That was
in part because Florida loosened various harvesting re-
strictions out of fear—ultimately unrealized—that the
Deepwater Horizon oil spill would contaminate its oyster
fisheries. 3 Trial Tr. 767–769. A former Florida official, one
of Florida’s lead witnesses, acknowledged that these man-
agement practices “ ‘bent’ ” Florida’s fisheries “ ‘until [they]
broke.’ ” Ga. Exh. 1357, p. 1; 4 Trial Tr. 877.
The record also shows that Florida failed to adequately
reshell its oyster bars. Reshelling is a century-old oyster-
management practice that involves replacing harvested
oyster shells with clean shells, which can serve as habitat
for young oysters. Id., at 907–908; 17 Trial Tr. 4390. Yet
in the years before the collapse, while Florida was harvest-
ing oysters at a record pace, it was simultaneously re-
shelling its oyster bars at a historically low rate. See Direct
Testimony of Romuald N. Lipcius ¶¶138–151 (Lipcius), and
Demos. 15, 16; see also Ga. Exh. 568, p. 5 (recommending
that Florida reshell 200 acres per year); 7 Trial Tr. 1692
(Florida reshelled 180 total acres in the 10 years before the
collapse).
Cite as: 592 U. S. ____ (2021) 7
Opinion of the Court
Georgia’s marine ecologist, Dr. Lipcius, demonstrated the
stark effects of Florida’s increased harvesting and lax re-
shelling efforts. Analyzing data on oyster densities precol-
lapse and postcollapse, Dr. Lipcius found that mean densi-
ties in the Bay’s most heavily harvested oyster bars
dropped by an average of 78%, while mean densities in-
creased by 3% to 13% at bars that either were not heavily
harvested or had been reshelled. Lipcius ¶¶41–44. Dr. Lip-
cius also found negligible differences in salinity among the
bars that he analyzed, suggesting that increased salinity
did not explain the variance in oyster densities. Id., ¶¶48–
51.
Florida does not meaningfully rebut this evidence. Yet
Florida nonetheless argues that Georgia’s overconsump-
tion—and the consequent increased salinity and preda-
tion—was the sole cause of the collapse, or at least a sub-
stantial factor contributing to it.* But here again, Florida’s
own witnesses suggest otherwise.
Dr. White, one of Florida’s ecology experts, modeled how
oyster biomass would have changed at two of the Bay’s ma-
jor oyster bars if Georgia had consumed less water in the
years leading up to the collapse. His modeling showed that
reducing Georgia’s consumption by an amount “similar to
the relief that Florida is requesting” in this case would have
increased oyster biomass by less than 1.5% in 2012. Up-
dated Pre-Filed Direct Testimony (PFDT) of J. Wilson
White 49–51, figs. 14, 15.
Florida does not explain how such minor fluctuations in
oyster biomass could have averted the collapse. Instead,
Florida points to testimony that increased streamflow
would have had “larger” effects on oyster biomass at oyster
bars closer to the river’s mouth. 7 Trial Tr. 1725; see also
——————
*We have not specified the causation standard applicable in equitable-
apportionment cases. We need not do so here, for Florida has failed to
establish a sufficient causal connection under any of the parties’ pro-
posed standards.
8 FLORIDA v. GEORGIA
Opinion of the Court
id., at 1868–1870. But it was Florida’s burden to quantify
how much larger the effects would have been, and its ex-
perts did not model biomass changes at bars near the river.
See 6 Trial Tr. 1571.
Other Florida experts reinforced Dr. White’s biomass
findings. One expert found that salinity reductions of
greater than 10 parts per thousand are “required” in order
to reduce predation by rock snails—one of the oyster’s fierc-
est predators. Fla. Exh. 797, p. 38; Updated PFDT of Mark
Berrigan ¶¶42–43 (Berrigan). Yet according to another
Florida expert, salinity throughout the Bay would have de-
clined by substantially less than 10 parts per thousand in
2012 even if Georgia had eliminated all of its consumption
from the Basin. PFDT of Marcia Greenblatt ¶¶4, 27, 30.
Together, these findings further undermine the asserted
link between Georgia’s consumption and decreased oyster
biomass.
In response to this empirical evidence, Florida relies pri-
marily on: (1) testimony from a local oysterman and a for-
mer Florida official that they witnessed high salinity and
significant oyster predation, including at private oyster
bars not subject to overharvesting, PFDT of Thomas L.
Ward ¶¶33–37; Berrigan ¶¶44–48; (2) reports by its own
agency blaming the collapse in part on salinity and preda-
tion, Joint Exhs. 50, 77; (3) a fishery-disaster declaration by
the National Oceanic and Atmospheric Administration
(NOAA) adopting the conclusion of Florida’s agency, Fla.
Exh. 413, p. 3; and (4) field experiments conducted by one
of Florida’s experts in the years after the collapse, which
purport to demonstrate a link between increased salinity
and predation, Updated PFDT of David Kimbro ¶¶63–90.
The fundamental problem with this evidence—a problem
that pervades Florida’s submission in this case—is that it
establishes at most that increased salinity and predation
contributed to the collapse, not that Georgia’s overconsump-
tion caused the increased salinity and predation. None of
Cite as: 592 U. S. ____ (2021) 9
Opinion of the Court
these witnesses or reports point to Georgia’s overconsump-
tion as a significant cause of the high salinity and preda-
tion. The NOAA, in fact, primarily blamed “prolonged
drought conditions” and the Corps’ reservoirs operations—
not Georgia’s consumption during drought conditions—for
the elevated levels of salinity and predation in the Bay. Fla.
Exh. 413, pp. 3–4. Other record evidence, moreover, indi-
cates that the unprecedented series of multiyear droughts,
as well as changes in seasonal rainfall patterns, may have
played a significant role. See PFDT of Dennis Lettenmaier
17, fig. 8; Direct Testimony of Wei Zeng ¶¶144–152. Given
these confounding factors, we do not think that Florida’s
evidence of high salinity and predation overcomes the data
and modeling of its own experts, which show that Georgia’s
consumption had little to no impact on the Bay’s oyster pop-
ulation.
Considering the record as a whole, Florida has not shown
that it is “highly probable” that Georgia’s alleged overcon-
sumption played more than a trivial role in the collapse of
Florida’s oyster fisheries. See Colorado II, 467 U. S., at 316.
Florida therefore has failed to carry its burden of proving
causation by clear and convincing evidence.
B
Florida also argues that Georgia’s overconsumption has
harmed river wildlife and plant life by disconnecting tribu-
taries, swamps, and sloughs from the Apalachicola River,
thereby drying out important habitats for river species.
The Special Master found “a complete lack of evidence” that
any river species suffered serious injury from Georgia’s al-
leged overconsumption, and we agree. Second Report of
Special Master 22.
In seeking to prove injury, Florida relied primarily on
species-specific “harm metrics” developed by Dr. Allan, one
of its ecology experts. Dr. Allan established minimum
river-flow regimes that he believed necessary for certain
10 FLORIDA v. GEORGIA
Opinion of the Court
species of fish, mussels, and trees to avoid “significant
harm” during dry months. Updated PFDT of J. David Allan
¶¶33–61 (Allan). He then sought to quantify the harm to
each species by totaling the number of days in which river
flows fell below his thresholds. Id., ¶¶62–63.
What Dr. Allan did not do, however, is show that his
harm metrics did or likely would translate into real-world
harm to the species that he studied. Indeed, Dr. Allan pro-
vided no data showing that the overall population of any
river species has declined in recent years. See 2 Trial Tr.
389–392, 395–396. And other evidence casts significant
doubt on Dr. Allan’s harm metrics. For instance, the U. S.
Fish & Wildlife Service found that the population of the fat
threeridge mussel—one of the species Dr. Allan analyzed—
“appears stable and may be increasing in size.” Joint Exh.
168, p. 125; Allan ¶42.
Without stronger evidence of actual past or threatened
harm to species in the Apalachicola River, we cannot find it
“highly probable” that these species have suffered serious
injury, let alone as a result of any overconsumption by
Georgia. See Colorado II, 467 U. S., at 316.
* * *
In short, Florida has not met the exacting standard nec-
essary to warrant the exercise of this Court’s extraordinary
authority to control the conduct of a coequal sovereign. We
emphasize that Georgia has an obligation to make reason-
able use of Basin waters in order to help conserve that in-
creasingly scarce resource. But in light of the record before
us, we must overrule Florida’s exceptions to the Special
Master’s Report and dismiss the case.
It is so ordered.