FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

NAVAJO NATION,

Plaintiff-Appellant,

v.

U.S. DEPARTMENT OF THE INTERIOR;

DEB HAALAND, Secretary of the 

Interior; UNITED STATES BUREAU OF 

RECLAMATION; BUREAU OF INDIAN 

AFFAIRS,

Defendants-Appellees,

STATE OF ARIZONA; CENTRAL 

ARIZONA WATER CONSERVATION 

DISTRICT; ARIZONA POWER 

AUTHORITY; SALT RIVER PROJECT 

AGRICULTURAL IMPROVEMENT AND 

POWER DISTRICT; SALT RIVER 

VALLEY WATER USERS’

ASSOCIATION; IMPERIAL IRRIGATION 

DISTRICT; METROPOLITAN WATER 

DISTRICT OF SOUTHERN CALIFORNIA;

COACHELLA VALLEY WATER 

DISTRICT; STATE OF NEVADA;

COLORADO RIVER COMMISSION OF 

NEVADA; SOUTHERN NEVADA 

WATER AUTHORITY; STATE OF 

COLORADO,

Intervenor-Defendants-Appellees.

No. 19-17088

D.C. No.

3:03-cv-00507-

GMS

OPINION
2 NAVAJO NATION V. USDOI

Appeal from the United States District Court

for the District of Arizona

G. Murray Snow, Chief District Judge, Presiding

Argued and Submitted October 16, 2020

Pasadena, California

Filed April 28, 2021

Before: Ronald M. Gould, Marsha S. Berzon, and

Kenneth K. Lee, Circuit Judges.

Opinion by Judge Gould;

Concurrence by Judge Lee

SUMMARY*

Water Rights / Tribal Matters

The panel reversed the district court’s dismissal, based 

on lack of jurisdiction, of Navajo Nation’s breach of trust 

claim alleging that Federal Appellees failed to consider the 

Nation’s as-yet-undetermined water rights in managing the 

Colorado River.

The district court held that any attempt by the Nation to 

amend its complaint was futile because the district court 

lacked jurisdiction to decide the breach of trust claim due to 

the Supreme Court reserving jurisdiction over allocation of 

rights to the Colorado River in Arizona v. California

* This summary constitutes no part of the opinion of the court. It 

has been prepared by court staff for the convenience of the reader.
NAVAJO NATION V. USDOI 3

(Arizona I), 373 U.S. 546 (1963) (opinion); accord Arizona 

v. California (1964 Decree), 376 U.S. 340, 353 (1964) 

(decree).

The panel held that the district court erred in dismissing 

the complaint because the amendment was not futile. 

Although the Supreme Court retained original jurisdiction 

over water rights claims to the Colorado River in Arizona I,

the Nation’s complaint did not seek a judicial quantification 

of rights to the River, and therefore, the panel need not 

decide whether the Supreme Court’s retained jurisdiction 

was exclusive. The panel concluded it had jurisdiction to 

consider the Nation’s claim, and the district court erred in 

holding otherwise.

The panel held, contrary to the Intervenors’ arguments 

on appeal, that the Nation’s claim was not barred by res 

judicata, despite the federal government’s representation of 

the Nation in Arizona I. The panel held that the Nation, here, 

asserted a different claim than the water rights claim the 

federal government could have asserted on the Nation’s 

behalf in Arizona I. The federal government’s fiduciary duty 

to the Nation was never at issue in Arizona I, and no final 

judgment was ever entered on the merits of any question 

concerning that subject.

Finally, the panel held that the district court erred in 

denying the Nation’s motion to amend and in dismissing the 

Nation’s complaint, because the complaint properly stated a 

breach of trust claim premised on the Nation’s treaties with 

the United States and the Nation’s federally reserved Winters

rights, especially when considered along with the Federal 

Appellees’ pervasive control over the Colorado River. At 

this early stage of the litigation, the panel declined to address 

whether the Nation’s Winters rights included rights to the 
4 NAVAJO NATION V. USDOI

mainstream of the Colorado River or to any other specific 

water resources. The panel remanded to the district court 

with instructions to permit the Nation to amend its 

complaint.

Judge Lee concurred. He wrote separately to emphasize 

that the Nation’s proposed injunctive relief should not and 

did not implicate the Supreme Court’s retained jurisdiction 

in the 1964 Decree.

COUNSEL

M. Kathryn Hoover (argued) and Stanley M. Pollack,

Navajo Nation Department of Justice, Window Rock, 

Arizona; Alice E. Walker and Gregg H. DeBie, Meyer 

Walker Condon & Walker P.C., Boulder, Colorado; for 

Plaintiff-Appellant.

John L. Smeltzer (argued), Mary Gabrielle Sprague, and 

Thomas Snodgrass, Attorneys; Environment and Natural 

Resources Division, United States Department of Justice,

Washington, D.C.; Robert Snow and Sarah Foley,

Attorneys, Solicitor’s Office, United States Department of 

the Interior, Washington, D.C.; for Defendants-Appellees.

Rita P. Maguire (argued), Rita P. Maguire PLLC, Phoenix, 

Arizona; Steven B. Abbott, Redwine and Sherrill LLP, 

Riverside, California; Kenneth C. Slowinski, Arizona 

Department of Water Resources, Phoenix, Arizona; Marcia 

Scully and Catherine M. Stites, Metropolitan Water District 

of Southern California, Los Angeles, California; Charles T. 

DuMars, Law & Resource Planning Associates P.C., 

Albuquerque, New Mexico; John B. Weldon Jr. and Lisa M. 

McKnight, Salmon Lewis & Weldon P.L.C., Phoenix, 
NAVAJO NATION V. USDOI 5

Arizona; Stuart L. Somach and Robert B. Hoffman, Somach 

Simmons & Dunn APC, Sacramento, California; Jay M. 

Johnson, Central Arizona Water Conservation District, 

Phoenix, Arizona; Aaron Ford, Attorney General; Christine 

Guerci-Nyhus, Special Counsel to the Colorado River 

Commission of Nevada; State of Nevada and Colorado River 

Commission of Nevada, Las Vegas, Nevada; Gregory J. 

Walch, General Counsel, Southern Nevada Water Authority, 

Las Vegas, Nevada; Lauren J. Caster and Bradley J. Pew, 

Fennemore Craig P.C., Phoenix, Arizona; for IntervenorDefendants-Appellees.

Monte Tyler Mills, Associate Professor and Director, 

Margery Hunter Brown Indian Law Clinic, Alexander 

Blewett III School of Law, University of Montana, 

Missoula, Montana, for Amici Curiae Law Professors.

David L. Gover, Joe M. Tenorio, and Matthew Campbell, 

Native American Rights Fund, Boulder, Colorado; Daniel D. 

Lewerenz, Native American Rights Fund, Washington, 

D.C.; Derrick Beetso, National Congress of American 

Indians, Washington, D.C.; for Amicus Curiae NCAI Fund.

OPINION

GOULD, Circuit Judge:

In 2003, the Navajo Nation (the Nation) sued the 

Department of the Interior (Interior), the Secretary of the 

Interior (the Secretary), the Bureau of Reclamation, and the 

Bureau of Indian Affairs (collectively, the Federal 

Appellees), bringing claims under the National 

Environmental Policy Act (NEPA) and a breach of trust 

claim for failure to consider the Nation’s as-yet-
6 NAVAJO NATION V. USDOI

undetermined water rights in managing the Colorado River. 

Several parties, including Arizona, Nevada, and various state 

water, irrigation, and agricultural districts and authorities 

(collectively, the Intervenors), intervened to protect their 

interests in the Colorado’s waters. In a prior appeal, we held 

that while the Nation lacked Article III standing to bring its 

NEPA claims, its breach of trust claim was not barred by 

sovereign immunity, and we remanded to the district court. 

Navajo Nation v. Dep’t of Interior (Navajo I), 876 F.3d 

1144, 1174 (9th Cir. 2017). After re-considering the breach 

of trust claim, the district court dismissed the Nation’s 

complaint because of its view that any attempt to amend the 

complaint was futile. The district court held that it lacked 

jurisdiction to decide the claim because the Supreme Court 

reserved jurisdiction over allocation of rights to the Colorado 

River in Arizona v. California (Arizona I), 373 U.S. 546 

(1963) (opinion); accord Arizona v. California (1964 

Decree), 376 U.S. 340, 353 (1964) (decree). The district 

court also held that the Nation did not identify a specific 

treaty, statute, or regulation that imposed an enforceable 

trust duty on the federal government that could be vindicated 

in federal court. The Nation appealed.

We conclude that the district court erred in dismissing 

the complaint because, in contrast to the district court’s 

determination, the amendment was not futile. Although the 

Supreme Court retained original jurisdiction over water 

rights claims to the Colorado River in Arizona I, the Nation’s 

complaint does not seek a judicial quantification of rights to 

the River, so we need not decide whether the Supreme 

Court’s retained jurisdiction is exclusive. And contrary to 

the Intervenors’ arguments on appeal, the Nation’s claim is 

not barred by res judicata, despite the federal government’s 

representation of the Nation in Arizona I. Finally, the district 

court erred in denying the Nation’s motion to amend and in 
NAVAJO NATION V. USDOI 7

dismissing the Nation’s complaint, because the complaint 

properly stated a breach of trust claim premised on the 

Nation’s treaties with the United States and the Nation’s 

federally reserved Winters rights, especially when 

considered along with the Federal Appellees’ pervasive 

control over the Colorado River. We remand to the district 

court with instructions to permit the Nation to amend its 

complaint.

I

The Nation is a federally recognized Indian tribe that has 

signed two treaties with the United States. In ratifying the 

first treaty in 1849, the United States placed the Navajo 

people “under the exclusive jurisdiction and protection of the 

. . . United States,” providing “that they are now, and will 

forever remain, under the aforesaid jurisdiction and 

protection.” Treaty with the Navaho, 1849 art. I (Sep. 9, 

1849), 9 Stat. 974. The Navajo Reservation (the 

“Reservation”) was established as the “permanent home” of 

the Nation by the 1868 Treaty between the United States of 

America and the Navajo Tribe of Indians, 1868 art. XIII 

(June 1, 1868), 15 Stat. 667 (1868 Treaty). The Reservation 

was later expanded by executive orders and acts of Congress.

The Reservation sprawls across Arizona, New Mexico, 

and Utah, and lies almost entirely within the drainage basin 

of the Colorado River. The Colorado River flows along and 

defines a significant part of the Reservation’s western 

border. Because much of the land in the Colorado River 

drainage basin is arid, competition for water from the 

Colorado River and its tributaries is fierce.

To resolve disputes arising from water scarcity, rights to 

the Colorado River’s waters are allocated through a series of 

federal treaties, statutes, regulations, and common law 
8 NAVAJO NATION V. USDOI

rulings; Supreme Court decrees; and interstate compacts. 

Collectively, this legal regime is known as the “Law of the 

River.”

A

The Law of the River begins with the 1922 Colorado 

River Compact (1922 Compact), which split the Colorado 

River water equally between two groups of states: the 

“Upper Basin” states, consisting of Colorado, New Mexico, 

Utah, and Wyoming, and the “Lower Basin” states: Arizona, 

California, and Nevada. 1922 Compact art. II, reprinted in

70 Cong. Rec. 324 (Dec. 10, 1928). Each group collectively 

received 7.5 million acre-feet per year (mafy) of water. Id. 

art. III. The 1922 Compact did not, however, apportion the 

7.5 mafy among the individual states in either the Upper or 

Lower Basin. See id. art. VIII. Nor did it “affect[] the 

obligations of the United States of America to Indian tribes.” 

Id. art. VII.

Six years later, Congress conditionally approved the 

1922 Compact through the Boulder Canyon Project Act 

(BCPA). 43 U.S.C. § 617 et seq. The BCPA allowed 

Interior to construct the Hoover Dam and a reservoir at Lake 

Mead. See id. § 617. It empowered the Secretary to contract 

for the storage and delivery of water in Lake Mead. See id. 

The BCPA also authorized construction of the Central 

Arizona Project (CAP), which consists of an extensive canal 

system that diverts water from Lake Havasu to 

municipalities, irrigation districts, and Indian tribes in 

central Arizona. See 43 U.S.C. § 1521. Finally, it 

authorized the Lower Basin States to negotiate a second 

compact dividing their 7.5 mafy share: 4.4 mafy to 

California, 2.8 to Arizona, and 0.3 to Nevada. See 43 U.S.C. 

§ 617c(a).
NAVAJO NATION V. USDOI 9

The 1922 Compact—including the second compact 

apportionment—was to take effect once all three Lower 

Basin states ratified it. See id. But Arizona, displeased with 

the Compact’s terms, failed to ratify it. So the issue of how 

to share the Lower Basin States’ apportionment went 

unresolved. See Arizona I, 373 U.S. at 561–62. 

Nonetheless, because six of the seven Basin states ratified 

the BCPA, the Secretary began contracting for water with 

the Lower Basin states.1 Id. at 562.

In 1952, still dissatisfied with its allotment, Arizona sued 

California in the Supreme Court, invoking the Court’s 

original jurisdiction. Id. at 550–51. Nevada and other Basin 

States intervened, as did the United States. Id. at 551.

In proceedings before a Special Master, the United States 

asserted claims to various water sources in the Colorado 

River Basin on behalf of twenty-five tribes. But the United 

States only asserted claims to the Colorado River 

mainstream on behalf of five tribes, and the Nation was not 

among them. Instead, the United States at that time limited 

the Nation’s claim to the Little Colorado River, one of the 

tributaries in the Colorado River system. Navajo I, 876 F.3d 

at 1156 n.13. The Nation, along with other tribes, sought the 

appointment of a Special Assistant Attorney General to 

represent their interests, but their request was denied. The 

Nation also sought to intervene in proceedings before the 

Special Master, but its motion to intervene was denied at the 

United States’ urging. See Response of the United States to 

the Motion on Behalf of the Navajo Tribe of Indians for 

1 The BCPA lowered the 1922 Compact’s ratification threshold: six 

states would suffice for ratification as long as California was among 

them and committed to a ceiling on its apportionment. See 43 U.S.C. 

§ 617c(a).
10 NAVAJO NATION V. USDOI

Leave to Intervene, Arizona I, 373 U.S. 546 (No. 8, 

Original).

The Supreme Court issued its decree in 1964. See 1964 

Decree, 376 U.S. 340. The Court excluded the Little 

Colorado River—and therefore the Nation’s claim—from 

the adjudication, along with other tributaries in the river 

system. See id. art. VIII(B), 376 U.S. at 352–53. It also 

affirmed the apportionment of the first 7.5 mafy among the 

Lower Basin States as specified in the BCPA and the 

accompanying second compact. Id. art. II(B), 376 U.S. at 

341–42. The Decree stated that in years where there is less 

than 7.5 million acre-feet available in the Lower Basin, 

Interior must first “provide[] for satisfaction of present 

perfected rights in the order of their priority dates without 

regard to state lines.” Id. art. II(B)(3), 376 U.S. at 342. 

Then, “after consultation with the parties to major delivery 

contracts and such representatives as the respective States 

may designate, [the Secretary] may apportion the amount 

remaining available for consumptive use in such manner as 

is consistent with” the BCPA, the 1964 Decree, and other 

applicable federal statutes. Id.

The 1964 Decree also determined the Winters rights of 

the five tribes for whom the federal government asserted 

federally reserved rights. See id. at 344–45. Under the 

Winters doctrine, “when the Federal Government withdraws 

its land from the public domain” for the purpose of 

establishing an Indian reservation, “the Government, by 

implication, reserves appurtenant water then unappropriated 

to the extent needed to accomplish the purpose of the 

reservation.” Cappaert v. United States, 426 U.S. 128, 138 

(1976); see Winters v. United States, 207 U.S. 564, 576 

(1908).
NAVAJO NATION V. USDOI 11

Water is essential to life on earth, see Sandra Alters, 

Biology: Understanding Life 39 (3d ed. 2000), and it is 

particularly essential for healthy human societies.2 Further, 

beyond the general import of water for societies, in the 

specific case of the Navajo Nation, news reports have 

indicated that the Nation’s shortage of water have in part 

caused exacerbation of the risks from COVID-19. Many 

homes on the Reservation lack running water, making it 

difficult for tribal members to wash their hands regularly. 

See Ian Lovett et. al, Covid-19 Stalks Large Families in 

Rural America, Wall St. J. (June 7, 2020), 

https://www.wsj.com/articles/covid-19-households-spreadcoronavirus-families-navajo-california-second-wave11591553896. The Nation has as a result been particularly 

affected by the current pandemic, with a death rate 

significantly higher than that of many other parts of the 

country. See id.3

2 It is by no accident that many of the world’s ancient civilizations 

were born in places such as the Tigris-Euphrates delta, and the valleys 

of the Nile, Indus, and Yellow Rivers. Pierre-Louis Viollet, Water 

Engineering in Ancient Civilizations9 (Forrest M. Holly trans., 2017). 

The engineers of classical Rome built a vast network of aqueducts that, 

at its peak, spanned over 250 miles in length. During the Last Gothic 

War, King Vitiges led an army of Ostrogoths to the gates of Rome itself. 

The invaders encircled the city and blocked off the aqueducts, keenly 

aware that the Romans could not survive a prolonged siege without 

access to water. See Peter J. Aicher, Guide to the Aqueducts of Ancient 

Rome 6 (1995). In more recent times, Israel, faced with a paucity of 

water, has developed techniques for managing wastewater and pioneered 

desalinization techniques. In 2011, Israel desalinated 296 million cubic 

meters (MCM) of water out of sea water, and forty-five MCM out of 

brackish water. Water Policy in Israel 5 (Nir Becker ed., 2013).

3 The vast majority of deaths on the Reservation due to COVID-19 

are among people aged sixty and older, including the hataałii, traditional 
12 NAVAJO NATION V. USDOI

In Winters, the United States, acting as trustee of the Fort 

Belknap Tribe, sought to enjoin upstream diversions on 

Montana’s Milk River from interfering with the Fort 

Belknap Reservation’s downstream diversions. See Winters, 

207 U.S. at 565. Although the 1888 treaty that established 

the Reservation made no express provision for tribal water 

rights to the Milk River, the United States maintained that 

the water had been impliedly reserved to fulfill the purpose 

of the reservation as a “permanent home and abiding place” 

for the Fort Belknap Tribe. Id. The Court agreed, noting 

that the Reservation lands “were arid, and, without 

irrigation, were practically valueless.” Id. at 576. The Court 

applied the Indian canons of construction, under which 

ambiguities in agreements and treaties with tribes “will be 

resolved from the standpoint of the Indians,” and held that 

the Tribe was entitled to federally reserved rights to the Milk 

River. Id.; see id. at 576–77.

Winters set a “solid foundation” for later decisions that 

reaffirmed the scope of Indian reserved water rights. Robert 

T. Anderson, Indian Water Rights and the Federal Trust 

Responsibility, 46 Nat. Res. J. 399, 414 (2006). Subsequent 

decisions have established that these rights are determined 

by federal, not state law. See 1 Cohen’s Handbook of 

Federal Indian Law § 19.03 (Nell Jessup Newton ed., 2019) 

(Cohen’s Handbook). Moreover, tribal water rights may 

trump water rights of state users, even when those users have 

medicine men and women entrusted with preserving the Nation’s 

cultural heritage. Jack Healy, Tribal Elders Are Dying From the 

Pandemic, Causing a Cultural Crisis for American Indians, N.Y. Times

(Jan. 12, 2021), https://www.nytimes.com/2021/01/12/us/tribal-eldersnative-americans-coronavirus.html.
NAVAJO NATION V. USDOI 13

been drawing from the water source for a longer time. See 

id.

In awarding five tribes federally reserved water rights, 

the Arizona Court reaffirmed the Winters doctrine, noting 

that “most of the [reservation] lands were of the desert 

kind—hot, scorching sands—and . . . water from the 

[Colorado] river would be essential to the life of the Indian 

people and to the animals they hunted and the crops they 

raised.” Arizona I, 373 U.S. at 599. These five tribes 

received rights to water commensurate with the “practically 

irrigable acreage” within each tribe’s reservation. Id. at 600; 

see 1964 Decree art. II(D), 376 U.S. at 343–45. However, 

the Supreme Court declined to adjudicate the claims of the 

twenty other tribes for whom the United States asserted 

claims—including the Nation’s. Arizona I, 373 U.S. at 595 

(“While the [Special] Master passed upon some of these 

claims, he declined to reach others, particularly those 

relating to tributaries. We approve his decision as to which 

claims required adjudication . . . .”).

B

Federal Appellees, through Interior and its Secretary, 

exercise pervasive control over the Colorado River pursuant 

to the BCPA, the 1964 Decree, and other components of the 

Law of the River. See id. at 593. The Secretary has 

discretion to apportion shortfalls in years of shortage, see id. 

at 593–94, and also has the authority to determine whether 

there is a surplus or shortage of water each year, see 1964 

Decree, art. II(B)(2)–(3), 376 U.S. at 342.

In 1968, Congress enacted the Colorado River Basin 

Project Act (the “Basin Act”), which requires Interior to 

manage Lake Mead, Lake Powell, and related facilities in 

coordination and under long-range operating criteria. 
14 NAVAJO NATION V. USDOI

43 U.S.C. § 1552(a). Each year, Interior must determine 

whether there will be enough water to satisfy the 7.5 mafy 

budgeted among the Lower Basin states, and whether and 

how much “surplus” water will be available. See 73 Fed. 

Reg. 19,873, 19,875 (Apr. 11, 2008). In 2001 and 2007, 

Interior adopted “surplus” and “shortage” guidelines to 

clarify how it determines whether a particular year was a 

“shortage” or “surplus” year. See 66 Fed. Reg. 7772 (Jan. 

25, 2001); 73 Fed. Reg. 19,873 (Apr. 11, 2008).

Before adopting the shortage guidelines, the Secretary 

published a draft environmental impact statement (EIS) 

discussing Indian Trust Assets, which are defined as legal 

interests in assets held in trust by the federal government for 

federally recognized tribes. See Final Environmental Impact 

Statement, Colorado River Interim Guidelines for Lower 

Basin Shortages and Coordinated Operations for Lake 

Powell and Lake Mead (Shortage Guidelines FEIS) 3-87 

(Oct. 2007). The EIS acknowledges that under the Winters

doctrine, the federal government impliedly “reserved water 

in an amount necessary to fulfill the purposes of an Indian 

reservation” for the Navajo Reservation. Id. at 3-96. The 

EIS also states that while “[t]he existence of a federally 

reserved right for the Navajo Nation to mainstream 

Colorado River has not been judicially determined at this 

time[, u]nquantified water rights of the Navajo Nation are 

considered an [Indian Trust Asset].” Id.

II

The Nation filed a complaint against Federal Appellees 

under the Administrative Procedure Act (APA), 5 U.S.C. 

§§ 701–706, challenging the 2001 Surplus Guidelines. 

Navajo I, 876 F.3d at 1159. The Nation alleged that Federal 

Appellees violated the National Environmental Policy Act 

(NEPA), 42 U.S.C. § 4321 et seq., and breached its trust 
NAVAJO NATION V. USDOI 15

obligations based on the Federal Appellees’ management of 

the Colorado River without considering or meeting the 

Nation’s unquantified federal reserved water rights and 

unmet water needs, Navajo I, 876 F.3d at 1159. Several 

parties—Arizona, Nevada, and various state water, 

irrigation, and agricultural districts and authorities 

(collectively, “Intervenors”)—intervened to protect their 

interests in the Colorado’s waters. Id. The district court 

dismissed the complaint, holding that the Nation lacked 

standing to bring its NEPA claims and that its breach of trust 

claim was barred by sovereign immunity.

On appeal, we agreed with the district court that the 

Nation lacked standing to bring its NEPA claims but 

reversed and remanded on the breach of trust claim. Id.

at 1174. We held that the waiver of sovereign immunity in 

§ 702 of the APA “applie[d] squarely to the Nation’s breach 

of trust claim.” Id. at 1173. Because the breach of trust 

claim was not barred by sovereign immunity, we instructed 

the district court to fully consider the claim on its merits, 

“after entertaining any request to amend the claim more fully 

to flesh it out.” Id.

On remand, the Nation twice moved for leave to file an 

amended complaint. The Proposed Third Amended 

Complaint (TAC) alleged that the Federal Appellees have 

failed to (1) “determine the quantities and sources of water 

required to make the Navajo Nation a permanent homeland 

for the Navajo People,” and (2) “protect the sovereign 

interests of the Navajo Nation by securing an adequate water 

supply to meet those homeland purposes.” The Intervenors 

opposed both motions to amend, arguing that because the 

United States could have asserted the Nation’s claim to the 

mainstream of the Colorado River in the Arizona v. 

California litigation and the rights to the River were fully 
16 NAVAJO NATION V. USDOI

adjudicated in that action, the Nation’s claim was barred by 

res judicata.

The district court denied both motions to amend and 

dismissed the Nation’s complaint with prejudice. The 

district court held that although a general trust relationship 

exists between the United States and the tribes, the Nation 

failed to identify a specific trust-creating statute, regulation, 

or other form of positive law that the federal government 

violated. And though the Nation argued that such a specific 

trust obligation is created under the Winters doctrine, the 

district court held that a determination of whether Winters 

rights attached to the mainstream of the Colorado River was 

jurisdictionally barred by the Supreme Court’s reservation 

of jurisdiction in Arizona v. California. We conclude that 

the Nation’s claim does not implicate the Court’s reservation 

of jurisdiction, and that it therefore was error for the district 

court not to grapple with the scope of Winters rights 

available to the Nation in connection with its current 

requests.

The district court further reasoned that even if it could 

decide the breach of trust claim, Winters rights alone do not 

give rise to specific and enforceable trust duties on the 

federal government. The district court also held that none of 

the treaties, statutes, and regulations that the Nation cited in 

support of its trust claim were “specific . . . trust-creating 

statute[s] or regulation[s] that the Government violated.” 

Finally, the district court held that the Nation could not 

allege a common law cause of action for breach of trust that 

is “wholly separate from any statutorily granted right.”

We disagree with the district court as to the role of 

Winters rights in establishing enforceable trust duties. 

Winters rights are necessarily implied in each treaty in which 

the government took land from Native Americans and 
NAVAJO NATION V. USDOI 17

established reservations that were to be permanent homes for 

them. That was the case with the Nation’s reservation. 

Federal Appellees have an irreversible and dramatically 

important trust duty requiring them to ensure adequate water 

for the health and safety of the Navajo Nation’s inhabitants 

in their permanent home reservation.

Because the district court concluded that the Nation’s 

attempts to amend its complaint were futile, the district court 

denied the motion to amend and dismissed the complaint. 

The Nation timely appealed. Although the district court did 

not decide the res judicata issue in dismissing the Nation’s 

complaint, Intervenors assert that res judicata defense on 

appeal.

This appeal presents three issues. First, we determine 

whether the Nation’s breach of trust claim falls within the 

Supreme Court’s reserved jurisdiction in Arizona v. 

California. If it does, we decide whether that jurisdiction is 

not only reserved, but also exclusive. Second, we determine 

whether the Nation’s claim is barred by res judicata. Third, 

we decide whether the Nation could properly state a claim 

for breach of trust such that amendment was not futile.

III

We review a district court’s denial of a motion to amend 

a complaint for abuse of discretion. Wheeler v. City of Santa 

Clara, 894 F.3d 1046, 1051 (9th Cir. 2018). “A district 

court’s exercise of discretion based on an erroneous 

interpretation of the law constitutes an abuse of discretion.” 

Ahlmeyer v. Nev. Sys. of Higher Educ., 555 F.3d 1051, 1055 

(9th Cir. 2009). Moreover, “[d]ismissal without leave to 

amend is improper unless it is clear, upon de novo review, 

that the complaint could not be saved by any amendment.” 

Polich v. Burlington N., Inc., 942 F.2d 1467, 1472 (9th Cir. 
18 NAVAJO NATION V. USDOI

1991). Finally, we review a district court’s decision to 

dismiss for lack of subject matter jurisdiction de novo. 

DaVinci Aircraft, Inc. v. United States, 926 F.3d 1117, 1122 

(9th Cir. 2019).

IV

A

We begin with the jurisdictional question. The district 

court determined it could not decide the Nation’s breach of 

trust claim because it falls within the Supreme Court’s 

reserved jurisdiction under Article IX of the 1964 Decree. 

Article IX provides that:

Any of the parties may apply at the foot of 

this decree for its amendment or for further 

relief. The Court retains jurisdiction of this 

suit for the purpose of any order, direction, or 

modification of the decree, or any 

supplementary decree, that may at any time 

be deemed proper in relation to the subject 

matter in controversy.

1964 Decree, art. IX, 376 U.S. at 353. The parties and the 

district court assumed that this provision reserves the 

Supreme Court’s exclusive jurisdiction over—and strips 

lower courts of jurisdiction to determine—whether the 

Nation has water rights to a specific allocation from the 

mainstream of the Colorado River. But in attempting to 

avoid Article IX’s jurisdictional bar, the Nation represents 

that it does not seek a judicial determination of its rights to 

the Colorado. The Nation argues that it merely seeks an 

injunction ordering the Federal Appellees to investigate the 

Nation’s needs for water, to develop a plan to meet those 

needs, and to exercise its authority over the management of 
NAVAJO NATION V. USDOI 19

the Colorado River consistent with that plan. Under this 

reading of the Nation’s claim, the district court only had to 

consider whether the Nation needs water to fulfill the 

promise of establishing the Navajo Reservation as a 

homeland for the Nation’s people.

We agree with the Nation’s characterization of its claim. 

A plain reading of the Nation’s complaint makes clear that it 

does not seek a quantification of its rights in the Colorado 

River. The Nation seeks an injunction “[r]equiring the 

Federal Appellees . . . (1) to determine the extent to which 

the Navajo Nation requires water . . . (2) to develop a plan to 

secure the water needed; (3) to exercise their authorities, 

including those for the management of the Colorado River, 

in a manner that does not interfere with the plan to secure the 

water needed . . . and (4) to require the Federal Appellees to 

analyze their actions . . . and adopt appropriate mitigation 

measures to offset any adverse effects from those actions.” 

Granting this scope of relief would not require a judicial 

quantification of the Nation’s rights to water from the River. 

Nor would it require any modification of the Arizona Decree. 

Furthermore, Article VIII(C) of the Decree provides that the 

Decree does not affect “[t]he rights or priorities, except as 

specific provision is made herein, of any Indian 

Reservation.” 1964 Decree, 376 U.S. at 353. As discussed 

infra, the Nation’s claim is not determined by any specific 

provision in the 1964 Decree, as none addresses the Navajo 

Nation’s water rights. The Nation’s breach of trust claim 

thus falls outside the scope of the Decree, and our 

jurisdiction is proper.

Because the Nation does not seek a judicial 

determination of its rights to the waters of the Colorado 

River, we need not resolve the scope of the Supreme Court’s 

reserved jurisdiction under Article IX. But we note that the 
20 NAVAJO NATION V. USDOI

Supreme Court’s own interpretation of the Decree does not 

expressly state whether Article IX’s reserved jurisdiction is 

exclusive. In the sequel to Arizona I, the federal government 

sought to increase the water allotments for the five tribes that 

were awarded federally reserved water rights in the original 

litigation, arguing that the earlier calculations of the 

practicably irrigable acreage within the reservations were 

inaccurate. Arizona v. California (Arizona II), 460 U.S. 605, 

608 (1983). The Court denied the request, and stated that if 

not for Article IX, the Court would have been barred by res 

judicata from re-opening the matter. Id. at 617–18. The 

Court explained that Article IX was “mainly a safety net 

added to retain jurisdiction and to ensure that we had not, by 

virtue of res judicata, precluded ourselves from adjusting the 

Decree in light of unforeseeable changes in circumstances.” 

Id. at 622. Because the Supreme Court is best positioned to 

interpret its own Decree, we defer to the interpretation it laid 

out in Arizona II and understand Article IX primarily as an 

authorization of jurisdiction, rather than a limitation on it.

Because the Nation neither seeks modification of the 

Decree nor seeks to relitigate any issues resolved in the 

Arizona cases, see infra, however, we need not resolve the 

scope of the Supreme Court’s jurisdiction under Article IX. 

We have jurisdiction to consider the Nation’s claim, and the 

district court erred in holding otherwise.

B

Having established that we have jurisdiction, we turn to 

the Intervenors’ argument that res judicata bars the Nation’s 

claim. Intervenors argue that the Nation’s breach of trust 

claim is barred by res judicata because the Nation 

effectively seeks a judicial determination of its rights to the 

Colorado River, which is a claim that the federal government 

could have asserted on the Nation’s behalf in Arizona I, but 
NAVAJO NATION V. USDOI 21

did not. We reject the Intervenors’ argument because the 

Nation’s claim is not barred by res judicata.

In Nevada v. United States, 463 U.S. 110 (1982), the 

Supreme Court held that res judicata barred the federal 

government from seeking additional water rights for the 

Pyramid Lake Tribe beyond the rights the tribe obtained in 

previous water rights litigation, id. at 113, 145. The Nevada 

Court considered “first if the cause of action which the 

Government now seeks to assert is the same cause of action 

that was asserted” in previous litigation, and then “whether 

the parties in the instant proceeding are identical to or in 

privity with” the parties in the previous litigation. Id. at 130 

(internal quotation marks omitted). The Court held that the 

federal government, in a decades-long adjudication that 

began in 1913, sought to “assert . . . the Reservation’s full 

water rights.” Id. at 132. Because Nevada involved the same 

parties “asserting the same reserved right” as that 

adjudicated by the previous litigation, id. at 134, the later 

claim was barred.

In this case, by contrast, the Nation asserts a different 

claim than the water rights claim the federal government 

could have asserted on the Nation’s behalf in Arizona I. The 

Nation’s claim, properly understood, is an action for breach 

of trust—not a claim seeking judicial quantification of its 

water rights. The federal government’s fiduciary duty to the 

Navajo Nation was never at issue in Arizona v. California, 

and no final judgment was ever entered on the merits of any 

question concerning that subject. Cf. Nevada, 463 U.S. 

at 129–30. As the Decree does not affect “[t]he rights or 

priorities” of Indian Reservation beyond those specifically 

enumerated, 1964 Decree, 376 U.S. at 353, the federal 

government’s fiduciary duty to the Nation remains unaltered 

by the Arizona litigation.
22 NAVAJO NATION V. USDOI

The Nation’s breach of trust claim is not barred by res 

judicata.

C

1

Finally, we address whether the Nation’s attempts to 

amend its complaint to plead their substantive breach of trust 

claim were futile. The Federal Appellees and the Intervenors 

argue that the district court correctly denied the Nation’s 

motion for leave to amend its complaint, because it could not 

point to any specific treaty provision, statute, or regulation 

that imposed a trust obligation on the Federal Appellees. We 

disagree and hold that the district court should have allowed 

the Nation to amend its complaint.

This circuit first considered the requirements a tribe must 

meet to bring a breach of trust action for non-monetary relief 

in Morongo Band of Mission Indians v. F.A.A., 161 F.3d 569 

(9th Cir. 1998). There, the Morongo Tribe challenged a 

Federal Aviation Administration (FAA) proposal that would 

have increased air traffic over reservation lands. Id. at 572–

73. The Tribe sought non-monetary relief under the APA, 

alleging violations of various statutes and FAA regulations. 

Id. at 572. We held that “unless there is a specific duty that 

has been placed on the government with respect to Indians, 

this responsibility is discharged by the agency’s compliance 

with general regulations and statutes not specifically aimed 

at protecting Indian tribes.” Id. at 574.

We addressed this issue again in Gros Ventre Tribe v. 

United States, 469 F.3d 801 (9th Cir. 2006). There, the Gros 

Ventre Tribe alleged that the federal government breached 

its trust obligations “by approving, permitting, and failing to 

reclaim” two cyanide heap-leach gold mines upriver from 
NAVAJO NATION V. USDOI 23

the Tribe’s reservation. Id. at 806. The panel explained that 

“an Indian tribe cannot force the government to take a 

specific action unless a treaty, statute or agreement imposes, 

expressly or by implication, that duty.” Id. at 810 (emphasis 

added) (quoting Shoshone-Bannock Tribes v. Reno, 56 F.3d 

1476, 1482 (D.C. Cir. 1995)). In holding that the Tribe 

failed to identify a treaty, statute, or regulation that would 

create an enforceable trust duty, we observed that the Tribe’s 

treaties with the federal government “at most . . . merely 

recognize[d] a general or limited trust obligation to protect 

the Indians against depredations on Reservation lands.” Id. 

at 812 (emphasis added). Because the Tribe sought an 

injunction requiring the federal government to “manage 

resources that exist off of the Reservation,” we held that no 

treaty provision imposed an enforceable trust duty that could 

be vindicated through injunctive relief. Id. at 812–13 

(emphasis added).

Morongo and Gros Ventre establish the governing 

standard here. Although Federal Appellees rely on another 

strain of cases concerning the need to identify specific 

statutory bases for obtaining monetary relief under the 

Tucker Act, 28 U.S.C. § 1491, those cases are not apposite.

The fiduciary claim in this case is one for injunctive 

relief under § 702 of the APA. In United States v. Mitchell 

(Mitchell I), 445 U.S. 535 (1980), individual members of the 

Quinault Tribe sued the federal government through the 

Tucker Act, 28 U.S.C. § 1491, over alleged mismanagement 

of timber resources on their allotted reservation lands, 

445 U.S. at 537, 539. The timber was managed by the 

Secretary of Interior under the General Allotment Act 

(GAA). Id. at 537. The Supreme Court rejected the tribal 

allottees’ argument that the GAA imposed enforceable trust 

duties on the federal government to manage tribal timber 
24 NAVAJO NATION V. USDOI

resources in a fiduciary capacity. Id. at 546. The Court 

explained that when Congress enacted the GAA, it intended 

that the federal government hold the land in trust “not 

because it wished the Government to control use of the land 

and be subject to money damages for breaches of fiduciary 

duty, but simply because it wished to prevent alienation of 

the land and to ensure that allottees would be immune from 

the state taxation.” Id. at 544. The Court remanded the case 

to the Court of Claims to consider whether the federal 

government could be held liable for breach of trust based on 

any other statutes. Id. at 546.

On remand, the Court of Claims held that the 

government was subject to suit for money damages based on 

various statutes and regulations detailing the federal 

government’s responsibilities in managing the tribal timber 

resources. United States v. Mitchell (Mitchell II), 463 U.S. 

206, 211 (1983). The Supreme Court affirmed, holding that 

the regulations and statutes created an enforceable trust 

obligation because they accorded the Secretary a “pervasive 

role in the sales of timber from Indian lands.” Id. at 219. 

The Court observed that a substantive right to sue under the 

Tucker Act “must be found in some other source of law, such 

as ‘the Constitution, or any Act of Congress, or any 

regulation of an executive department.’” Id. at 216 (quoting 

28 U.S.C. § 1491). “[T]he claimant must demonstrate that 

the source of substantive law he relies upon ‘can fairly be 

interpreted as mandating compensation by the Federal 

Government for the damages sustained.’” Id. at 216–17 

(quoting United States v. Testan, 424 U.S. 392, 400 (1976)).

These Supreme Court decisions concerned suits brought 

for money damages under the Tucker Act, 28 U.S.C. § 1491, 

and the Indian Tucker Act, 28 U.S.C. § 1505. But this case 
NAVAJO NATION V. USDOI 25

involves a claim for injunctive relief brought under § 702 of 

the APA, so we are not bound by those decisions.

A more recent decision, United States v. Jicarilla, 

564 U.S. 162 (2011), concerned a breach of trust claim in a 

discovery context and imported requirements similar to 

those stated in the Tucker Act and Indian Tucker Act cases. 

In Jicarilla, the Court decided whether the Jicarilla Apache 

Nation (the “Tribe”) could assert the “fiduciary exception” 

to the attorney-client privilege in a suit against the federal 

government, id. at 165. At first, the Tribe sued the 

government for breach of trust, seeking monetary damages 

for alleged mismanagement of tribal funds. Id. at 166. Then 

the parties participated in alternative dispute resolution, 

wherein the government refused to produce certain 

documents, claiming the attorney-client privilege. Id. So 

the Tribe moved to compel production of those documents. 

Id. at 167. It asserted the “fiduciary exception” to the 

attorney-client privilege, which states that a trustee cannot 

assert the privilege against a beneficiary after obtaining legal 

advice on how to execute its fiduciary obligations. Id.

The Court held that the Tribe could not compel the 

federal government to produce privileged documents in 

discovery based on the fiduciary exception, because it failed 

to “point to a right conferred by statute or regulation in order 

to obtain otherwise privileged information from the 

Government against its wishes.” Id. at 178. In doing so, the 

Court observed that it had previously “found that particular 

‘statutes and regulations . . . clearly establish fiduciary 

obligations of the Government’ in some areas.” Id. at 177 

(ellipsis in original) (quoting Mitchell II, 463 U.S. at 226). 

But the Court also explained that “[o]nce federal law 

imposes such duties, the common law ‘could play a role’” in 

defining the scope of those duties. Id. (quoting United States 
26 NAVAJO NATION V. USDOI

v. Navajo Nation, 556 U.S. 287, 301 (2009)). Again, 

Jicarilla was at bottom a suit for monetary relief. Its ruling 

must be understood against that background.

2

Federal Appellees contend that under these precedents, 

the Nation has failed to state a breach of trust claim because 

it cannot point to any treaty, statute, or regulation that 

imposes an affirmative trust duty on the federal government 

to ensure that the Nation has an adequate water supply. We 

disagree.

Here, the injunctive relief the Nation seeks would not 

require the federal government to manage off-reservation 

resources. Instead, the Nation seeks an injunction 

compelling the Secretary to determine the extent to which 

the Reservation requires water from sources other than the 

Little Colorado River to fulfill the Reservation’s purpose of 

establishing a permanent homeland for the Nation. The 

mainstream of the Colorado River is appurtenant to the 

Nation and defines a significant segment of the 

Reservation’s western boundary.

Moreover, neither Morongo nor Gros Ventre nor 

Jicarilla involved claims to vindicate Winters rights, which 

provide the foundation of the Nation’s claim here. Unlike 

the plaintiffs in those cases, the Nation, in pointing to its 

reserved water rights, has identified specific treaty, statutory, 

and regulatory provisions that impose fiduciary obligations 

on Federal Appellees—namely, those provisions of the 

Nation’s various treaties and related statutes and executive 

orders that establish the Navajo Reservation and, under the 

long-established Winters doctrine, give rise to implied water 

rights to make the reservation viable.
NAVAJO NATION V. USDOI 27

Under Winters, the federal government “reserve[d] 

appurtenant water then unappropriated to the extent needed 

to accomplish” the purpose of establishing the Reservation 

as a permanent homeland for the Navajo people. Navajo I, 

876 F.3d at 1155 (quoting Cappaert, 426 U.S. at 138). In 

Colville Confederated Tribes v. Walton, 647 F.2d 42 (9th 

Cir. 1981), we noted that while “[t]he specific purposes of 

an Indian reservation . . . were often unarticulated,” “[t]he 

general purpose, to provide a home for the Indians, is a broad 

one and must be liberally construed,” id. at 47. It is clear 

that the Reservation cannot exist as a viable homeland for 

the Nation without an adequate water supply. As the Court 

observed in Arizona I:

Most of the land in [the reservations 

appurtenant to the Colorado River] is and 

always has been arid. If the water necessary 

to sustain life is to be had, it must come from 

the Colorado River or its tributaries. It can 

be said without overstatement that when the 

Indians were put on these reservations they 

were not considered to be located in the most 

desirable area of the Nation. It is impossible 

to believe that when Congress created the 

great Colorado River Indian Reservation and 

when the Executive Department of this 

Nation created the other reservations they 

were unaware that most of the lands were of 

the desert kind—hot, scorching sands—and 

that water from the river would be essential 

to the life of the Indian people and to the 

animals they hunted and the crops they 

raised.

373 U.S. at 598–99.
28 NAVAJO NATION V. USDOI

We stress that Winters rights are long-established and 

clearly qualify as rights “by implication” under a treaty. 

Gros Ventre, 469 F.3d at 810 (quoting Shoshone-Bannock, 

56 F.3d at 1482). Those necessarily implied rights are just 

as important as express ones. It is not our province to modify 

the Supreme Court’s definitive law establishing water rights 

as contained in treaties establishing Native American 

reservations, whether express or not. None of the twists and 

turns in the responsible federal agencies’ and courts’ 

historical treatment of Indian law has brought the Winters 

declaration of necessarily implied water rights into question.

We hold in particular that, under Winters, Federal 

Appellees have a duty to protect the Nation’s water supply 

that arises, in part, from specific provisions in the 1868 

Treaty that contemplated farming by the members of the 

Reservation. The Treaty provides that individual members 

of the Nation may select plots of land if they “desire to 

commence farming.” 1868 Treaty, art. V. Tribal members 

who took up farming would be entitled to “seeds and 

agricultural implements” to help make this transition. Id. art. 

VII. The Treaty’s farming-related provisions, which sought 

to encourage the Nation’s transition to an agrarian lifestyle, 

would have been meaningless unless the Nation had 

sufficient access to water.4

 Indeed, in Winters itself, the 

Court explained that at the time the Fort Belknap Tribe 

signed its treaty with the federal government, it was the 

government’s policy to change the Tribe’s “habits and 

4 In the Nation’s first motion for leave to file a third amended 

complaint, the Nation sought to add, in addition to its breach of fiduciary 

duty claim, a claim for breach of the 1849 and 1868 Treaties, but later 

omitted that claim from its renewed motion. On remand, the district 

court is instructed that the Nation should be permitted to amend its 

complaint in this respect if it seeks to do so.
NAVAJO NATION V. USDOI 29

wants” to those of “a pastoral and civilized people.” 

Winters, 207 U.S. at 576. We do not pass judgment on the 

wisdom of such a policy, nor on the merits of particular 

allegations that may be offered relating to agrarian rights, but 

it is clear that the Winters Court based its holding in large 

part on the fact that without water, the reservation lands 

could not support an agrarian lifestyle in accordance with 

government policy. See id. (“The lands were arid, and, 

without irrigation, were practically valueless.”).

That the farming provisions in the 1868 Treaty may 

serve as the “specific statute” that satisfies Jicarilla, 

Morongo, and Gros Ventre is consistent with more general 

principles concerning the interpretation of treaties between 

the United States and Indian tribes. The Supreme Court has 

explained: “A treaty, including one between the United 

States and an Indian tribe, is essentially a contract between 

two sovereign nations.” Washington v. Wash. State Com. 

Passenger Fishing Vessel Ass’n, 443 U.S. 658, 675, 

modified sub nom. Washington v. United States, 444 U.S. 

816 (1979) (citing Lone Wolf v. Hitchcock, 187 U.S. 553 

(1979)). We have inferred a promise of water rights into 

treaties that contained no explicit reservation of those rights. 

See, e.g., Arizona I, 373 U.S. at 599; Agua Caliente Band of 

Cahuilla Indians v. Coachella Valley Water Dist., 849 F.3d 

1262, 1268 (9th Cir. 2017).

We did so in United States v. Adair, 723 F.2d 1394 (9th 

Cir. 1983), for example, where the Klamath Tribe’s treaty 

with the United States merely preserved the right to “hunt, 

fish, and gather on their reservation,” Id. at 1398. We 

recognized that a main purpose of the treaty was to “secure 

to the Tribe a continuation of its traditional hunting and 

fishing lifestyle.” Id. at 1409. We reasoned that this purpose 

would have been defeated unless the Klamath Tribe had the 
30 NAVAJO NATION V. USDOI

right to enjoy and use water sufficient to ensure an adequate 

supply of game and fish. See id. at 1411. Although the 

claimed water rights at issue in that case were “essentially 

nonconsumptive in nature,” id. at 1418, Adair stands for the 

broader proposition that we may read water rights into a 

treaty where those rights are necessary to fulfill the treaty’s 

primary purpose. See United States v. Washington, 853 F.3d 

946, 965 (9th Cir. 2017) (“Thus, even if Governor Stevens 

had made no explicit promise, we would infer, as in Winters

and Adair, a promise to ‘support the purpose’ of the 

Treaties.”).

Interior’s documents also demonstrate that the Federal 

Appellees have acknowledged their trust responsibilities to 

protect the Nation’s Winters rights. For example, the final 

EIS relating to Interior’s shortage guidelines acknowledges 

that the federal government impliedly “reserved water in an 

amount necessary to fulfill the purposes of” the Navajo 

Reservation. Shortage Guidelines FEIS, 3-96. The EIS also 

states that the Nation’s unquantified water rights are 

considered an Indian Trust Asset, which Interior recognizes 

as interests that the federal government holds in trust for 

recognized Indian tribes, and that the federal government 

must protect. Id.

The Nation’s breach of trust claim is also strengthened 

and reinforced by the Secretary’s pervasive control over the 

Colorado River. The BCPA requires the United States and 

all Colorado River users to “observe and be subject to and 

controlled by” the 1922 Compact, which apportioned the 

Colorado River’s waters among the Lower Basin states. 

43 U.S.C. § 617g(a). But within the general allocation of 

water that the 1922 Compact entails, the Secretary has 

pervasive authority “both to carry out the allocation of the 

waters of the main Colorado River among the Lower Basin 
NAVAJO NATION V. USDOI 31

States and to decide which users within each State would get 

water.” Arizona I, 373 U.S. at 580.

In this respect, the Supreme Court’s reasoning in 

Mitchell II is pertinent: just as the statutes and regulations in 

that case gave the Secretary a “pervasive role in the sales of 

timber from Indian lands,” 463 U.S. at 219, so too do the 

BCPA and other components of the Law of the River confer 

broad authority upon the Secretary to manage and contract 

for Colorado River water, see, e.g., BCPA, 43 U.S.C. § 617d 

(“No person shall have or be entitled to have the use for any 

purpose of the water stored as aforesaid except by contract 

made as herein stated.”). This pervasive control over the 

Colorado River, coupled with the Nation’s Winters rights, 

outlines the scope of Federal Appellees’ trust duties.

Our holding is consistent with the Supreme Court’s 

decision in United States v. Navajo Nation. Although the 

Court there held that “[t]he Federal Government’s liability 

cannot be premised on control alone,” 556 U.S. at 301, the 

Court also explained that once a plaintiff identifies a specific 

duty-imposing treaty, statute, or regulation, “then trust 

principles (including any such principles premised on 

‘control’) could play a role in ‘inferring that the trust 

obligation [is] enforceable by damages.’” Id. (quoting 

United States v. White Mountain Apache Tribe, 537 U.S. 

465, 473 (2003)). The Nation—which in any case does not 

here seek money damages—has identified a specific dutyimposing treaty, as we have explained.

To summarize: We hold that the Nation has successfully 

identified specific treaty, statutory, and regulatory 

provisions that, taken together, anchor its breach of trust 

claim. First, we have the implied treaty rights recognized in 

Winters, which in itself gives the Tribe the right to proceed 

on a breach of trust claim here; second, the 1868 Treaty, 
32 NAVAJO NATION V. USDOI

which recognizes the Nation’s right to farm Reservation 

lands and, under Adair, gives rise to an implied right to the 

water necessary to do so; third, the BCPA and other statutes 

that grant the Secretary authority to exercise pervasive 

control over the Colorado River; and fourth and finally, the 

Nation has pointed to Interior regulations and documents in 

which Federal Appellees have undertaken to protect Indian 

Trust Assets, including the Nation’s as-yet-unquantified 

Winters rights.

Having established that a fiduciary duty exists, we hold 

that common-law sources of the trust doctrine and the 

control the Secretary exercises over the Colorado River 

firmly establish the Federal Appellees’ duty to protect and 

preserve the Nation’s right to water. Under Winters, when 

the federal government took the Reservation into trust, it 

“reserve[d] appurtenant water then unappropriated to the 

extent needed to accomplish” that purpose. Navajo I, 

876 F.3d at 1155 (quoting Cappaert, 426 U.S. at 138). 

These rights are recognized as reserved by treaty, applying 

the canon that in “agreements and treaties with the Indians, 

ambiguities occurring will be resolved from the standpoint 

of the Indians.” Winters, 207 U.S. at 576; see Washington, 

853 F.3d at 965. Though water rights are not expressly 

stated in the Nation’s treaties with the United States, the 

Winters rights that attach to the Reservation are sufficiently 

well-established to create an implied fiduciary obligation on 

the Federal Appellees. See Gros Ventre, 469 F.3d at 810 

(noting that a specific duty can be imposed by “a treaty, 

statute or agreement . . . expressly or by implication.”) 

(quoting Shoshone-Bannock, 56 F.2d at 1482).

We recognize that no court has yet quantified the 

Nation’s Winters rights. But the fault for the exceedingly 

long delay in that respect, if any, lies with Federal Appellees. 
NAVAJO NATION V. USDOI 33

As trustee, the federal government has the power to not only 

bring water rights claims on behalf of the tribes, but also to 

bind them in litigation. See Nevada, 463 U.S. at 135. When 

the Nation tried to intervene in Arizona v. California, the 

federal government opposed the Nation’s motion. And in 

the more than half of a century since the Supreme Court 

issued its 1964 Decree, the Nation has never had its Winters

rights adjudicated or quantified by any court.5 This result is 

but one example of what a commentator has described as the 

federal government’s failure “to secure, protect, and develop 

adequate water supplies for many Indian tribes.” Cohen's 

Handbook § 19.06. Indeed, “[i]n the history of the United 

States Government’s treatment of Indian tribes, its failure to 

protect Indian water rights for use on the reservations it set 

aside for them is one of the sorrier chapters.” 6

 Id. (citing 

National Water Comm’n, Water Policies for the Future: 

Final Report to the President and to the Congress of the 

United States, 474–75 (1973)); see also Anderson, supra, at 

400.

The Supreme Court could not have intended to hamstring 

the Winters doctrine—which has remained good law for 

more than one hundred years—by preventing tribes from 

seeking vindication of their water rights by the federal 

government when the government has failed to discharge its 

duties as trustee. Such a perverse reading of the Court’s 

5 The Nation is actively seeking water from various sources in other 

litigation. See generally Navajo I, 876 F.3d at 1156 n.14.

6 Perhaps recognizing this failure, some members of Congress have 

proposed legislation that would empower the Administrator of the 

Environmental Protection Agency to “give priority to projects that 

respond to emergency situations where a lack of access to clean drinking 

water threatens the health of Tribal populations” in the Columbia River 

Basin. S. 421, 117th Cong. § 2 (2021).
34 NAVAJO NATION V. USDOI

precedents would render ineffectual the federal 

government’s promise to “charge[] itself with moral 

obligations of the highest responsibility and trust,” Seminole 

Nation v. United States, 316 U.S. 286, 297 (1942), by 

ensuring that the tribes of this country can make their 

reservation lands livable. This principle takes on even more 

importance in an era in which the COVID-19 pandemic 

renders reservation lands more dangerous to tribal 

members—particularly when they lack adequate water for 

health and safety purposes.

The Nation’s attempts to amend its complaint were not 

futile. The Nation can state a cognizable claim for breach of 

trust because it has identified specific regulations and treaty 

provisions that can “fairly be interpreted,” Mitchell II, 

463 U.S. at 218, as establishing Federal Appellees’ fiduciary 

obligations to ensure that the Nation’s Reservation has the 

water it needs to exist as a viable homeland for the Navajo 

people.

At this early stage of litigation, we decline to address 

whether the Nation’s Winters rights include rights to the 

mainstream of the Colorado River or to any other specific 

water sources. We hold only that the Nation may properly 

base its breach of trust claim on water rights derived from its 

treaties with the United States under Winters, and so may 

amend its complaint to so allege.

V

Because the district court’s denial of the Nation’s motion 

for leave to amend and subsequent dismissal of the Nation’s 

complaint were based on legal errors, the court abused its 

discretion. Applying the correct legal principles, we hold 

that the Nation’s attempts to amend its complaint were not 

futile. We reverse the district court’s dismissal of the 
NAVAJO NATION V. USDOI 35

Nation’s complaint and remand to the district court with 

instructions to permit amendment to the complaint 

consistent with this opinion.7

REVERSED AND REMANDED.

LEE, Circuit Judge, concurring:

I write separately to emphasize that the Nation’s 

proposed injunctive relief should not and does not implicate 

the Supreme Court’s retained jurisdiction in Arizona v. 

California (1964 Decree), 376 U.S. 340, 353 (1964).

When the Supreme Court first adjudicated the rights to 

the Colorado River, it issued a Decree listing the Indian 

tribes and other entities holding present perfected rights to 

the mainstream. Id. at 344–46. Article IX of the Decree 

“retain[ed] jurisdiction . . . for the purpose of any order,

direction, or modification of the decree, or any 

supplementary decree . . .” Id. at 353. Since then, there have 

been several iterations of the Arizona v. California litigation, 

but none has explicitly addressed whether Article IX 

reserves exclusive jurisdiction for adjudication of rights to 

7 As the concurrence recognizes, we need not and do not decide 

whether the Supreme Court’s retained jurisdiction in the 1964 Decree is 

exclusive. That is because the Nation’s claim does not seek a 

quantification of any rights it may have to the Colorado River 

mainstream. If, however, Federal Appellees later determine that they 

cannot meet their trust obligation to provide adequate water for the 

Nation unless the jurisdictional question is resolved, then they can 

petition the Supreme Court for modification of the 1964 Decree.
36 NAVAJO NATION V. USDOI

the mainstream. See, e.g., Arizona v. California (Arizona II), 

460 U.S. 605, 622 (1983).

In this case, the Nation seeks additional water for its 

Reservation, and both the parties and the district court 

considered whether the Supreme Court’s retained 

jurisdiction applied. But our decision does not answer that 

question, as the Nation’s Proposed Third Amended 

Complaint (“TAC”) does not, on its face, actually seek rights 

to the mainstream.

The Nation’s TAC seeks injunctive relief requiring, in 

part, that the Federal Defendants “determine the extent to 

which the Navajo Nation requires water from sources other 

than the Little Colorado River to enable its Reservation to 

serve as a permanent homeland for the Navajo Nation and

its members” and “develop a plan to secure the water 

needed.” The Nation asserts, and our decision affirms, that 

this proposed injunction does not ask the district court to 

quantify any rights that the Nation may have to the Colorado 

River mainstream. This narrow construction of the proposed 

relief is imperative, as it allows the Nation to pursue its 

claims without raising the separate and more complex issue 

of the Supreme Court’s retained jurisdiction.

Thus, on remand and in all future proceedings, the 

TAC’s proposed injunctive relief should not be construed as 

implicitly authorizing a reassessment of the rights to the 

Colorado River mainstream. In other words, the requested 

relief that the Federal Defendants develop a plan to meet the 

Nation’s water needs cannot be used as a backdoor attempt 

to allocate the rights to the mainstream. If such rights are to 

be reassessed, that action may be taken only after resolving 

the jurisdictional question raised by Article IX of the 1964 

Decree.