PLAINTIFFS’ NOTICE OF SUPPLEMENTAL AUTHORITY 1

JULIA A. OLSON (OR Bar 062230) 

julia@ourchildrenstrust.org

Our Children’s Trust

1216 Lincoln Street

Eugene, OR 97401

Tel: (415) 786-4825 

PHILIP L. GREGORY (pro hac vice)

pgregory@gregorylawgroup.com

Gregory Law Group

1250 Godetia Drive

Redwood City, CA 94062

Tel: (650) 278-2957

ANDREA K. RODGERS (OR Bar 041029)

andrea@ourchildrenstrust.org

Our Children’s Trust

3026 NW Esplanade

Seattle, WA 98117

Tel: (206) 696-2851

Attorneys for Plaintiffs 

UNITED STATES DISTRICT COURT

DISTRICT OF OREGON

KELSEY CASCADIA ROSE JULIANA; 

XIUHTEZCATL TONATIUH M., through his 

Guardian Tamara Roske-Martinez; et al.,

Plaintiffs,

v.

The UNITED STATES OF AMERICA; et al., 

Defendants.

Case No.: 6:15-cv-01517-AA

PLAINTIFFS’ NOTICE OF

SUPPLEMENTAL AUTHORITY

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 1 of 11
PLAINTIFFS’ NOTICE OF SUPPLEMENTAL AUTHORITY 2

Plaintiffs hereby provide notice of supplemental authority of a new opinion from the United 

States Supreme Court, issued on November 22, 2021, Mississippi v. Tennessee, -- S.Ct. – (2021), 

2021 WL 5434188, slip opinion attached to this notice. 

A unanimous opinion by Chief Justice Roberts, Mississippi v. Tennessee, supports the 

broad principle that even after a case is dismissed for failing to plead a viable remedy, a motion to 

amend could be brought to cure the pleading deficiency. By way of background, after first being 

dismissed from Federal District Court, Mississippi brought an original action in the Supreme Court 

against Tennessee for novel damages and other relief related to the pumping of groundwater by

Memphis from the Middle Claiborne Aquifer, a water resource that lies beneath eight States. 

Mississippi, 2021 WL 5434188 *3, 4. Mississippi argued Tennessee’s pumping—using wells 

located entirely in Tennessee—siphons water away from Mississippi and amounted to a tortious 

taking of groundwater owned by Mississippi. Id. at *4. In its complaint, Mississippi expressly 

disclaimed any equitable apportionment remedy, the Court’s traditional remedy in transboundary 

resource cases between states. Id. The Special Master appointed by the Supreme Court, to oversee 

motions practice, discovery, and a five-day evidentiary hearing, recommended the Court dismiss 

the complaint but grant Mississippi leave to amend to bring an equitable apportionment claim. Id. 

Mississippi challenged the recommendation to dismiss and never sought leave to amend;

Tennessee objected to the recommendation to grant Mississippi leave to file an amended 

complaint. Id.

The Court was “[c]onfronted” with a “matter of first impression” as to available judicial 

remedies for interstate groundwater disputes and focused its “analysis on whether equitable 

apportionment of the Middle Claiborne Aquifer would be ‘sufficiently similar’ to past applications

of the doctrine to warrant the same treatment.” Mississippi, 2021 WL 5434188 *5. The unanimous 

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 2 of 11
PLAINTIFFS’ NOTICE OF SUPPLEMENTAL AUTHORITY 3

Court dismissed Mississippi’s complaint because it had not sought the only relief the Court held it

could seek for a transboundary water resource dispute—equitable apportionment. Mississippi, 

2021 WL 5434188 *5-7. The Supreme Court declined “to decide whether Mississippi should be 

granted” leave to amend, “because the State has never sought it.” Id. at *7. The Court concluded: 

“As Mississippi has neither sought leave to amend nor tendered a proposed complaint seeking 

equitable apportionment, we have no occasion to determine how these and other pertinent 

principles might apply.” Id. 

However, the Court left open the possibility that leave to amend could nonetheless be 

sought after dismissal: “Finally, if Mississippi were to seek leave to amend, its complaint would 

be subject to our longstanding rule that a ‘State seeking equitable apportionment under our original 

jurisdiction must prove by clear and convincing evidence some real and substantial injury or 

damage.’” Id. at *7. (citation omitted). The phrase “if Mississippi were to seek leave to amend . . 

. .” shows that, simply because the Supreme Court ultimately dismissed the case of first impression

in its original form, such dismissal does not preclude leave to amend, even seven years after the 

case was filed, after a five-day evidentiary hearing, and even when a party has disavowed the very 

remedy that would open the door to leave to amend. The Supreme Court signaled that Mississippi 

would likely have been allowed leave to amend, yet Mississippi had not sought leave. Id. Indeed, 

the Supreme Court goes so far as to map out the proper complaint for Mississippi to bring, which 

“might also require the joinder of additional parties” and require a pleading that there is “clear and 

convincing evidence” of “some real and substantial injury or damage.” Id. (internal quotations and 

citations omitted).

Unlike the State of Mississippi, since the first Motion to Dismiss filed by Defendants in 

the instant case, Plaintiffs have requested leave to amend if their claims, including issues of first 

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 3 of 11
PLAINTIFFS’ NOTICE OF SUPPLEMENTAL AUTHORITY 4

impression, were dismissed on standing or other jurisdictional grounds as soon as Defendants filed 

their motion to dismiss in 2016. Doc. 41 at 45. (citations omitted) (“If this Court finds facial 

deficiencies with Plaintiffs’ standing allegations or finds the FAC fails to state a claim, Plaintiffs 

respectfully request leave to amend.”). Mississippi v. Tennessee stands for the broad principle that

the remedy sought can be amended to cure a jurisdictional deficiency, and jurisdictional dismissal 

of a case for an improper remedy does not, as Defendants have argued, mean the case is over and 

the deficiency cannot be cured. Mississippi v. Tennessee makes clear that, in matters of first 

impression, leave to amend is a viable pathway after dismissal to cure a remedial deficiency, and 

it supports Plaintiffs’ Motion for Leave to File Amended Complaint. Doc. 462. 

This Court should grant Plaintiffs’ Motion forthwith.

DATED this 29th day of November, 2021.

Respectfully submitted,

/s/ Julia A. Olson________________

JULIA A. OLSON (OR Bar 062230)

julia@ourchildrenstrust.org

PHILIP L. GREGORY (pro hac vice)

pgregory@gregorylawgroup.com 

ANDREA K. RODGERS (OR Bar 041029)

andrea@ourchildrenstrust.org

Attorneys for Plaintiffs

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 4 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 1

2021 WL 5434188

Only the Westlaw citation is currently available.

Supreme Court of the United States.

STATE OF MISSISSIPPI, Plaintiff

v.

TENNESSEE, City of Memphis, Tennessee,

and Memphis Light, Gas & Water Division

No. 143, Orig.

|

Argued October 4, 2021

|

Decided November 22, 2021

Synopsis

Background: The State of Mississippi brought original

action against the State of Tennessee, city, and city's

water utility seeking damages, as well as declaratory and

injunctive relief, for the allegedly tortious taking of hundreds

of billions of gallons of water belonging to Mississippi

through the pumping, from wells located within Tennessee, of

groundwater from an aquifer located underneath both states,

as well as parts of six other states, in order to provide drinking

water to the city. After Mississippi's motion for leave to

file a bill of complaint was granted, a Special Master was

appointed, who subsequently issued a report recommending

that Mississippi's complaint be dismissed with leave to

amend. Both Mississippi and Tennessee filed exceptions.

Holdings: The Supreme Court, Chief Justice Roberts, held

that:

on issue of first impression, the aquifer's waters were subject

to the judicial remedy of equitable apportionment, and

Supreme Court would decline to grant Mississippi leave to

file amended complaint to seek equitable apportionment.

Exceptions overruled in part and sustained in part, and case

dismissed.

Syllabus*

Mississippi brought an original action against Tennessee

for damages and other relief related to the pumping of

groundwater by the City of Memphis from the Middle

Claiborne Aquifer, a valuable water resource that lies beneath

eight States. Mississippi argues that Tennessee's pumping

—using wells Mississippi concedes are located entirely

in Tennessee—siphons water away from Mississippi and

amounts to a tortious taking of groundwater owned by

Mississippi. Mississippi expressly disclaims any equitable

apportionment remedy, arguing that the “fundamental

premise of this Court's equitable apportionment jurisprudence

—that each of the opposing States has an equality of

right to use the waters at issue—does not apply to this

dispute.” Complaint ¶49. The Special Master appointed by

the Court to assess Mississippi's claims determined that the

aquifer is an interstate water resource and that equitable

apportionment is the exclusive judicial remedy. Because

Mississippi's complaint did not seek equitable apportionment,

the Special Master recommended that the Court dismiss the

complaint but grant Mississippi leave to amend. Mississippi

challenges the recommendation to dismiss; Tennessee objects

to the recommendation to grant Mississippi leave to file an

amended complaint.

Held: The waters of the Middle Claiborne Aquifer are

subject to the judicial remedy of equitable apportionment;

Mississippi's complaint is dismissed without leave to amend.

Pp. –––– – ––––.

(a) The doctrine of equitable apportionment aims to produce a

fair allocation of a shared water resource between two or more

States, see Colorado v. New Mexico, 459 U.S. 176, 183, based

on the principle that States have an equal right to reasonable

use of shared water resources. Florida v. Georgia, 592 U.S.

––––, ––––. The Court has applied the doctrine to interstate

rivers and streams, see South Carolina v. North Carolina, 558

U.S. 256, to disputes over interstate river basins, see Florida

v. Georgia, 585 U.S. ––––, ––––, and in situations where the

pumping of groundwater has affected the flow of interstate

surface waters, see Nebraska v. Wyoming, 515 U.S. 1, 14.

The Court has also applied the doctrine to anadromous fish

that migrate between the Pacific Ocean and spawning grounds

in the Columbia-Snake River system, “travel[ing] through

several States during their lifetime.” Idaho ex rel. Evans v.

Oregon, 462 U.S. 1017, 1018–1019, 1024.

The Court has not before addressed whether equitable

apportionment applies to interstate aquifers. Equitable

apportionment of the Middle Claiborne Aquifer is

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 5 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 2

“sufficiently similar” to past applications of the doctrine

to warrant the same treatment, for several reasons. Id., at

1024. First, the Court has applied equitable apportionment

when transboundary water resources were at issue. Here

the Middle Claiborne Aquifer's “multistate character” seems

beyond dispute. Sporhase v. Nebraska ex rel. Douglas,

458 U.S. 941, 953. Second, the Middle Claiborne Aquifer

contains water that flows naturally between the States, and

the Court's equitable apportionment cases have all concerned

such water, Kansas v. Colorado, 206 U.S. 46, 98, or fish

that live in it, Idaho ex rel. Evans, 462 U.S., at 1024. While

Mississippi contends the natural transboundary flow of the

Middle Claiborne Aquifer is slower than some streams and

rivers, the Court has applied equitable apportionment even

to streams that run dry from time to time. See Kansas,

206 U.S., at 115. The speed of the flow does not place

the aquifer beyond equitable apportionment. Finally, actions

taken in Tennessee to pump water from the aquifer clearly

have effects on the portion of the aquifer that underlies

Mississippi. Tennessee's pumping has contributed to a cone

of depression that extends miles into northern Mississippi,

and Mississippi itself contends that this cone of depression

has reduced groundwater storage and pressure in northern

Mississippi. Such interstate effects are a hallmark of the

Court's equitable apportionment cases, see, e.g., Florida, 592

U.S., at ––––. For all these reasons, the Court holds that

the judicial remedy of equitable apportionment applies to the

waters of the Middle Claiborne Aquifer. Pp. –––– – ––––.

*2 (b) The Court rejects Mississippi's contention that it has

a sovereign ownership right to all water beneath its surface

that precludes application of equitable apportionment. The

Court has “consistently denied” the proposition that a State

may exercise exclusive ownership or control of interstate

“waters flowing within her boundaries.” Hinderlider v. La

Plata River & Cherry Creek Ditch Co., 304 U.S. 92, 102.

Although the Court's past equitable apportionment cases have

generally concerned streams and rivers, no basis exists for

a different result in the context of the Middle Claiborne

Aquifer. To the contrary, Mississippi's ownership approach

would allow an upstream State to completely cut off flow to

a downstream one, a result contrary to the Court's equitable

apportionment jurisprudence. The Court's decision in Tarrant

Regional Water Dist. v. Herrmann, 569 U.S. 614, does not

support Mississippi's position. Tarrant concerned whether

one State could cross another's boundaries to access a shared

water resource under the terms of an interstate compact. The

Court did not consider equitable apportionment, because the

affected States had negotiated a compact that determined

their respective rights to the resource. To the extent Tarrant

stands for the broader proposition that one State may not

physically enter another to take water in the absence of an

express agreement, that principle is not implicated here. The

parties have stipulated all of Tennessee's wells are drilled

straight down and do not cross the Mississippi-Tennessee

border. While the origin of an interstate water resource may

be relevant to the terms of an equitable apportionment, that

feature alone cannot place the resource outside the doctrine

itself. Because the waters contained in the Middle Claiborne

Aquifer are subject to equitable apportionment, the Court

overrules Mississippi's exceptions and adopts the Special

Master's recommendation to dismiss the bill of complaint. Pp.

–––– – ––––.

(c) Mississippi has neither sought leave to amend its

complaint nor tendered a proposed complaint seeking

equitable apportionment. The Court does not address

whether Mississippi should be granted such leave and

sustains Tennessee's objection to the Special Master's

recommendation to grant Mississippi leave to amend. Pp.

–––– – ––––.

Exceptions overruled in part and sustained in part, and case

dismissed.

Roberts, C.J., delivered the opinion for a unanimous Court.

ON EXCEPTIONS TO REPORT OF SPECIAL MASTER

Attorneys and Law Firms

John V. Coghlan, Deputy Solicitor General, for Plaintiff.

David C. Frederick, for Defendants.

Frederick Liu for the United States as amicus curiae, by

special leave of the Court, in support of overruling plaintiff's

exceptions

Jim Hood, Attorney General, State of Mississippi, Geoffrey

C. Morgan, Assistant Attorney General, George W. Neville,

Harold E. Pizzetta, III, Alison E. O'Neal, Mississippi Attorney

General's Office, Jackson, MS, C. Michael Ellingburg,

Counsel of Record, Larry D. Moffett, Daniel Coker Horton

& Bell, P.A., Jackson, MS, John W. (Don) Barrett, David

M. McMullan, Jr., Barrett Law Group, P.A., Lexington, MS,

George B. Ready, George B. Ready Attorneys, Hernando,

MS, Charles Barrett, Charles Barrett, P.C., Nashville, TN, for

Plaintiff.

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 6 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 3

Lynn Fitch, Attorney General, State of Mississippi, Tricia

Beale, Ta'shia S. Gordon, Mississippi Attorney, General's

Office, Jackson, MS, C. Michael Ellingburg, Counsel of

Record, Ellingburg Law Firm, Pllc, Flowood, MS, Larry D.

Moffett, Law Office of Larry D., Moffett, Pllc, Oxford, MS,

Charles Barrett, William J. Harbison, II, Neal & Harwell, Plc,

Nashville, TN, Edward C. Taylor, Daniel Coker Horton &

Bell, P.A., Gulfport, MS, for Plaintiff.

David C. Frederick, Joshua D. Branson, Grace W.

Knofczynski, Alejandra Avila, Kellogg, Hansen, Todd Figel

& Frederick P.L.L.C., Washington, D.C., Herbert H. Slatery

III, Attorney General, Andrée Sophia Blumstein, Solicitor

General, Sohnia W. Hong, Senior Counsel, Counsel of

Record, Nashville, TN, David L. Bearman, Counsel of

Record, Kristine L. Roberts, Baker, Donelson, Bearman,

Caldwell & Berkowitz, Pc, Memphis, TN, Cheryl W.

Patterson, Charlotte Knight Griffin, Memphis Light, Gas

& Water Division, Memphis, TN, Jennifer Sink, City of

Memphis, TN, for Defendants.

Opinion

Chief Justice ROBERTS delivered the opinion of the Court.

The City of Memphis sits on the banks of the Mississippi

River in the southwest corner of Tennessee. Arkansas marks

the City's western border, and Mississippi its southern.

Hundreds of feet beneath Memphis lies one of the City's most

valuable resources: the Middle Claiborne Aquifer. Workers

discovered the aquifer in 1886 while drilling a well for the

Bohlen-Huse Ice Company. Ever since, water pumped from

the aquifer has provided Memphis with an abundant supply

of clean, affordable drinking water.

The Middle Claiborne Aquifer underlies other States too,

including Mississippi. This case began in 2014 when

Mississippi invoked our original jurisdiction and sought leave

to file a bill of complaint against Tennessee. Mississippi

alleges that Tennessee's pumping has taken hundreds of

billions of gallons of water that were once located beneath

Mississippi. It seeks at least $615 million in damages,

as well as declaratory and injunctive relief. We granted

Mississippi leave to file its complaint and appointed a Special

Master to oversee proceedings. The Special Master has

now issued his report, which recommends that this Court

dismiss Mississippi's complaint with leave to amend. Both

Mississippi and Tennessee have filed exceptions.

I

A

Layers of rock, clay, silt, sand, and gravel exist below

the Earth's surface. Groundwater percolates through the

spaces in and around these materials, sometimes forming

underground reservoirs of water known as aquifers. Some

aquifers are small, while others span tens of thousands

of square miles. The Middle Claiborne Aquifer is one

of the latter. It underlies portions of eight States in

the Mississippi River Basin: Alabama, Arkansas, Illinois,

Kentucky, Louisiana, Mississippi, Missouri, and Tennessee.

See Report of Special Master 16; Hearing Tr. 278–279. Many

of these States, including Mississippi and Tennessee, draw

significant amounts of groundwater from the aquifer. Id., at

660–662, 1038–1040; Joint Exh. J–71.

To extract water from an aquifer, people drill wells. Pumps

then draw water to the surface, where it is processed and

piped to customers. Pumping does not just bring water to

the surface; it also lowers water pressure at the site of

the well. Water is naturally drawn to this area of lower

pressure. This, in turn, “causes a pattern of lower or depressed

water levels around the wells.” Report of Special Master 13.

Hydrogeologists call such areas “cones of depression.” These

cones of depression can be local—say, the size of a backyard.

Or they can be regional, stretching out for many miles from a

pumping site. See id., at 21–23; Hearing Tr. 176, 188, 435.

*3 The City of Memphis, through its public utility, the

Memphis Light, Gas and Water Division (MLGW), pumps

approximately 120 million gallons of groundwater from the

Middle Claiborne Aquifer each day. Id., at 186, 200; Pl. Exh.

P–157. It does so using more than 160 wells located in and

around Memphis. Joint Statement of Stipulated and Contested

Facts 101. Some of these wells are located just a few miles

from the Mississippi-Tennessee border, though all are drilled

straight down such that none crosses the physical border

between the States. Id., at 101–102, 106. MLGW's pumping

contributes to a cone of depression that underlies both the

City of Memphis and DeSoto County, Mississippi. Report of

Special Master 21–23; Hearing Tr. 206, 435–436, 525.

Mississippi argues that MLGW's pumping has altered the

historic flow of groundwater within the Middle Claiborne

Aquifer. Mississippi concedes that some water naturally flows

from the part of the aquifer beneath Mississippi to the part

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 7 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 4

beneath Tennessee. But only to the extent of some 30 to

60 feet per year. See Exceptions Brief for Mississippi 8;

see also Report of Special Master 24 (“Mississippi does not

dispute the expert consensus that at least some quantity of

groundwater ... crossed the border under natural conditions.”).

Mississippi contends that MLGW's pumping has substantially

hastened this existing flow, allowing Memphis to take

billions of gallons of groundwater that otherwise would have

remained under Mississippi for thousands of years.

B

In 2005, prior to the present litigation, the Attorney General of

Mississippi sued the City of Memphis and MLGW in Federal

District Court. The suit alleged that Memphis had wrongfully

appropriated groundwater belonging to Mississippi through

its pumping activities. Mississippi sought hundreds of

millions of dollars in damages.

The District Court dismissed the suit for failure to join

Tennessee, which it determined was an indispensable party.

Hood ex rel. Miss. v. Memphis, 533 F. Supp. 2d 646, 651 (ND

Miss. 2008). The Fifth Circuit then affirmed. Hood ex rel.

Miss. v. Memphis, 570 F. 3d 625 (2009).

Both decisions turned in large part on what is known as

“equitable apportionment.” Under that doctrine, this Court

allocates rights to a disputed interstate water resource after

one State sues another under our original jurisdiction.

See Kansas v. Colorado, 206 U.S. 46, 97–98 (1907).

Traditionally, equitable apportionment has been the exclusive

judicial remedy for interstate water disputes, unless a statute,

compact, or prior apportionment controls. This Court has

never before held that an interstate aquifer is subject to

equitable apportionment, so Mississippi's suit implicated a

question of first impression.

The Court of Appeals, affirming the District Court, held that

interstate aquifers are comparable to interstate rivers and

are thus subject to equitable apportionment. It reasoned that

an aquifer “flows, if slowly.” Hood ex rel. Miss., 570 F.

3d, at 630. And it said the fact that an aquifer is “located

underground, as opposed to resting above ground,” was

of “no analytical significance.” Ibid. Because determining

“Mississippi and Tennessee's relative rights to the Aquifer”

brought the case within the equitable apportionment doctrine,

the Court of Appeals affirmed the District Court's holding that

Tennessee was an indispensable party. Id., at 630–631; see

also Fed. Rule Civ. Proc. 19(a). Joinder of Tennessee in the

lower federal courts was not possible, however, because this

Court has exclusive jurisdiction over suits between States. See

U.S. Const., Art. III, § 2; 28 U.S. C. § 1251(a). So the Fifth

Circuit held that the District Court had properly dismissed the

suit. Hood ex rel. Miss., 570 F. 3d, at 632–633; Fed. Rule Civ.

Proc. 19(b).

*4 Mississippi then petitioned for a writ of certiorari. It also

sought leave to file a bill of complaint against Tennessee,

Memphis, and MLGW under our original jurisdiction. The

proposed complaint requested over $1 billion in damages for

the alleged taking of Mississippi's water. In the alternative, it

sought equitable apportionment of the aquifer, with a damages

award for past diversions of groundwater. We declined to

grant certiorari, 559 U.S. 904 (2010), and denied without

prejudice Mississippi's request for leave to file a bill of

complaint, 559 U.S. 901 (2010).

C

In 2014, Mississippi again sought leave from this Court to

file a bill of complaint against Tennessee, Memphis, and

MLGW. That is the basis of this suit. Mississippi's complaint

alleges that MLGW “has forcibly siphoned into Tennessee

hundreds of billions of gallons of high quality groundwater

owned by Mississippi.” Complaint ¶23. It says that MLGW's

“mechanical pumping” is to blame and that the “groundwater

taken by Defendants from within Mississippi's borders would

have never under normal, natural circumstances been drawn

into Tennessee.” Id., ¶24. This “wrongful taking,” the State

contends, “is evidenced by a substantial drop in pressure

and corresponding drawdown of stored groundwater” in

northwest Mississippi, and by a cone of depression extending

miles into its territory. Id., ¶25. As a result, Mississippi says,

it has to drill its own wells deeper to access the aquifer, and

use more electricity to pump water to the surface. Id., ¶54(b).

Mississippi claims an absolute “ownership” right to all

groundwater beneath its surface—even after that water has

crossed its borders. See id., ¶¶8–12, 39. It argues that

Tennessee's pumping thus amounts to a tortious taking of

property, and it seeks at least $615 million in damages.

See id., ¶¶55–56. Mississippi expressly disclaims equitable

apportionment, arguing that the “fundamental premise of this

Court's equitable apportionment jurisprudence—that each of

the opposing States has an equality of right to use the waters

at issue—does not apply to this dispute.” Id., ¶49.

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 8 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 5

We granted Mississippi leave to file its complaint and

appointed Judge Eugene E. Siler, Jr., of the Sixth Circuit

to serve as Special Master. He has ably discharged his

duties. Following motions practice, discovery, and a fiveday evidentiary hearing, the Special Master issued a report

recommending that we dismiss Mississippi's complaint,

but with leave to amend. He first determined that the

Middle Claiborne Aquifer is an interstate water resource.

He found that the aquifer is a “single hydrogeological

unit,” that Tennessee's pumping affects groundwater

beneath Mississippi, and that prior to such pumping,

“groundwater flowed between Mississippi and Tennessee”—

a fact Mississippi “does not dispute.” Report of Special

Master 15–24.

The Special Master then concluded that, because the aquifer

is an interstate water resource, equitable apportionment

is the appropriate remedy. He recognized that equitable

apportionment “stands alone as the federal common-law

principle for disputes over interstate water,” id., at 31, and saw

“no compelling reason to chart a new path for groundwater

resources,” id., at 26. Because Mississippi's complaint

did not seek equitable apportionment, the Special Master

recommends that we dismiss it. But he also recommends

that we grant Mississippi leave to file an amended complaint

seeking equitable apportionment, though the State has not yet

sought such leave.

Mississippi and Tennessee both filed exceptions to the

Special Master's report. Mississippi objects to the Special

Master's recommendation that we dismiss the suit. It

argues that the Special Master erred in finding the water

in the Middle Claiborne Aquifer subject to equitable

apportionment. Tennessee objects only to the Special Master's

recommendation that we grant Mississippi leave to amend its

complaint.

*5 We “conduct an independent review of the record, and

assume the ultimate responsibility for deciding all matters.”

Kansas v. Nebraska, 574 U.S. 445, 453 (2015) (internal

quotation marks omitted). Based on that review, we dismiss

Mississippi's complaint and decline to grant leave to amend.

II

A

Equitable apportionment aims to produce a fair allocation

of a shared water resource between two or more States. See

Colorado v. New Mexico, 459 U.S. 176, 183 (1982). The

doctrine's “guiding principle” is that States “have an equal

right to make a reasonable use” of a shared water resource.

Florida v. Georgia, 592 U.S. ––––, –––– (2021) (slip op., at

4) (internal quotation marks omitted).

We pioneered the doctrine in Kansas v. Colorado, 206 U.S.

46. Since then, we have often applied it to interstate rivers and

streams. See South Carolina v. North Carolina, 558 U.S. 256

(2010); Colorado v. New Mexico, 459 U.S. 176; Nebraska

v. Wyoming, 325 U.S. 589 (1945); Wyoming v. Colorado,

259 U.S. 419 (1922). We have also applied the doctrine to

disputes over interstate river basins, see Florida v. Georgia,

585 U.S. ––––, –––– – –––– (2018) (slip op., at 2–3), and in

situations where the pumping of groundwater has affected the

flow of interstate surface waters, see Nebraska v. Wyoming,

515 U.S. 1, 14 (1995). We have even applied the doctrine

to anadromous fish—such as Chinook salmon and steelhead

trout—that migrate between the Pacific Ocean and spawning

grounds in the Columbia-Snake River system, “travel[ing]

through several States during their lifetime.” See Idaho ex rel.

Evans v. Oregon, 462 U.S. 1017, 1018–1019, 1024 (1983).

Mississippi correctly observes that we have never considered

whether equitable apportionment applies to interstate

aquifers. See Exceptions Brief for Mississippi 28. Confronted

as we are with this matter of first impression, we resist general

propositions and focus our analysis on whether equitable

apportionment of the Middle Claiborne Aquifer would be

“sufficiently similar” to past applications of the doctrine to

warrant the same treatment. Idaho ex rel. Evans, 462 U.S., at

1024 (adopting such an approach in extending the doctrine to

anadromous fish). We conclude that it would.

First, we have applied equitable apportionment only when

transboundary resources were at issue. See Virginia v.

Maryland, 540 U.S. 56, 74, n. 9 (2003); Colorado v. New

Mexico, 459 U.S., at 183. The Middle Claiborne Aquifer's

“multistate character” seems beyond dispute. See Sporhase

v. Nebraska ex rel. Douglas, 458 U.S. 941, 953 (1982).

Mississippi concedes that the “geologic formation in which

the groundwater is stored straddles two states.” Complaint

¶41. Indeed, a core premise of Mississippi's suit is that

Tennessee is pumping water that was once in Mississippi. The

evidence shows that wells in Memphis and wells in northwest

Mississippi are “pumping from the same aquifer.” Hearing

Tr. 492; see Report of Special Master 20 (noting that the

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 9 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 6

“scientific consensus holds that the Middle Claiborne Aquifer

is a single hydrogeological unit” spanning multiple States).

Also pertinent is that the Middle Claiborne Aquifer contains

water that flows naturally between the States. All of our

equitable apportionment cases have concerned such water,

Kansas v. Colorado, 206 U.S., at 98, or fish that live

in it, Idaho ex rel. Evans, 462 U.S., at 1024. Mississippi

suggests the Middle Claiborne Aquifer is distinguishable

from interstate rivers and streams because its natural flow is

“extremely slow.” Exceptions Brief for Mississippi 8. But we

have long applied equitable apportionment even to streams

that run dry from time to time. See Kansas v. Colorado, 206

U.S., at 115. And although the transboundary flow here may

be a mere “one or two inches per day,” Exceptions Brief

for Mississippi 8, that amounts to over 35 million gallons

of water per day, and over ten billion gallons per year, see

Hearing Tr. 532–533. So the speed of the flow, at least in

the context of this case, does not place the aquifer beyond

equitable apportionment.

*6 Finally, it is clear that actions in Tennessee “reach[ ]

through the agency of natural laws” to affect the portion of the

aquifer that underlies Mississippi. Kansas v. Colorado, 206

U.S., at 97. Tennessee's pumping has contributed to a cone

of depression that extends miles into northern Mississippi.

Hearing Tr. 484–485, 501–502, 926; see also Report of

Special Master 22–23. Mississippi itself contends that this

cone of depression has reduced groundwater storage and

pressure in northern Mississippi. See Complaint ¶¶25, 54.

It also alleges that Tennessee's pumping is “siphoning”

tens of millions of gallons of groundwater each day from

Mississippi's portion of the aquifer. Id., ¶54. Such interstate

effects are a hallmark of our equitable apportionment cases.

See, e.g., Florida v. Georgia, 592 U.S., at –––– – –––– (2021)

(slip op., at 2–3) (examining the effects of Georgia's water use

on Florida's oyster fisheries and river ecosystem).

For these reasons, we hold that the waters of the Middle

Claiborne Aquifer are subject to the judicial remedy of

equitable apportionment.

B

Mississippi contends that it has sovereign ownership of all

groundwater beneath its surface, so equitable apportionment

ought not apply. We see things differently. It is certainly true

that “each State has full jurisdiction over the lands within

its borders, including the beds of streams and other waters.”

Kansas v. Colorado, 206 U.S., at 93. But such jurisdiction

does not confer unfettered “ownership or control” of flowing

interstate waters themselves. Wyoming v. Colorado, 259

U.S., at 464. Thus, we have “consistently denied” the

proposition that a State may exercise exclusive ownership or

control of interstate “waters flowing within her boundaries.”

Hinderlider v. La Plata River & Cherry Creek Ditch Co.,

304 U.S. 92, 102 (1938). Although our past cases have

generally concerned streams and rivers, we see no basis for

a different result in the context of the Middle Claiborne

Aquifer. When a water resource is shared between several

States, each one “has an interest which should be respected

by the other.” Wyoming v. Colorado, 259 U.S., at 466.

Mississippi's ownership approach would allow an upstream

State to completely cut off flow to a downstream one, a result

contrary to our equitable apportionment jurisprudence.

Mississippi argues that our decision in Tarrant Regional

Water Dist. v. Herrmann, 569 U.S. 614 (2013), supports its

position. We disagree. Tarrant concerned the interpretation

of an interstate compact. We held that the compact did not

authorize the party States to “cross each other's boundaries to

access a shared pool of water.” Id., at 627. Our decision turned

on the language of the compact and background principles of

contract law. We did not consider equitable apportionment,

because the affected States had taken it upon themselves to

negotiate a compact that determined their respective rights to

the resource in question.

To the extent Tarrant stands for the broader proposition that

one State may not physically enter another to take water

in the absence of an express agreement, that principle is

not implicated here. The parties have stipulated that all of

Tennessee's wells are drilled straight down and do not cross

the Mississippi-Tennessee border. See Joint Statement of

Stipulated and Contested Facts 106. When Tennessee pumps

groundwater, it is pumping water located within its own

territory. That some of the water was previously located in

Mississippi is of no moment, just as it was not dispositive

that the river at issue in Colorado v. New Mexico started in

Colorado, 459 U.S., at 181, n. 8, or that certain fish at issue

in Idaho ex rel. Evans hatched in Idaho, 462 U.S., at 1028, n.

12. The origin of an interstate water resource may be relevant

to the terms of an equitable apportionment. But that feature

alone cannot place the resource outside the doctrine itself.

*7 We conclude that the waters contained in the Middle

Claiborne Aquifer are subject to equitable apportionment.

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 10 of 11
State of Mississippi v. Tennessee, --- S.Ct. ---- (2021)

 © 2021 Thomson Reuters. No claim to original U.S. Government Works. 7

We therefore overrule Mississippi's exceptions and adopt

the Special Master's recommendation to dismiss the bill of

complaint.

III

After recommending that this Court dismiss Mississippi's suit,

the Special Master went on to recommend that we grant the

State leave to file an amended complaint seeking equitable

apportionment. We decline to decide whether Mississippi

should be granted such leave, because the State has never

sought it. As Mississippi itself emphasizes—literally—it has

“not yet requested equitable apportionment.” Reply Brief to

Defendants' Exception 7.

Nor can we assume Mississippi will do so. Mississippi's initial

pleadings in this case disavowed equitable apportionment

entirely. See Complaint ¶38 (“This case does not fall within

the Court's equitable apportionment jurisprudence.”). The

State instead sought relief under principles of tort law. And

the proceedings below reflected this posture, focusing on the

physical properties of the aquifer and Tennessee's pumping.

An equitable apportionment case would require us to consider

a broader range of evidence. Such evidence often includes

not only the physical properties and flow of a water resource,

but also existing uses, the availability of alternatives, practical

effects, and the costs and benefits to the States involved. See

Florida v. Georgia, 585 U.S., at –––– – –––– (2018) (slip op.,

at 13–14); South Carolina, 558 U.S., at 271–272; Colorado

v. New Mexico, 459 U.S., at 183, 186–187. A just equitable

apportionment might also require the joinder of additional

parties, cf. Fed. Rule Civ. Proc. 19(a), as Mississippi and

Tennessee are not the only States that rely on the Middle

Claiborne Aquifer for groundwater, see Hearing Tr. 660–

662, 1038–1040; Joint Exh. J–71. Finally, if Mississippi

were to seek leave to amend, its complaint would be subject

to our longstanding rule that a “State seeking equitable

apportionment under our original jurisdiction must prove

by clear and convincing evidence some real and substantial

injury or damage.” Idaho ex rel. Evans, 462 U.S., at 1027.

As Mississippi has neither sought leave to amend nor tendered

a proposed complaint seeking equitable apportionment, we

have no occasion to determine how these and other pertinent

principles might apply.

* * *

Mississippi has failed to show that it is entitled to relief.

We therefore overrule Mississippi's exceptions to the Special

Master's report, sustain Tennessee's, and dismiss the case.

It is so ordered.

All Citations

--- S.Ct. ----, 2021 WL 5434188

Footnotes

* 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.

End of Document © 2021 Thomson Reuters. No claim to original U.S.

Government Works.

Case 6:15-cv-01517-AA Document 521 Filed 11/29/21 Page 11 of 11