By: Gregory Esser

Arizona is the first and only state in the nation to depart from the federal precedent established by the U.S. Supreme Court in 1963 in Arizona v. California for the method of measuring Indian tribes’ federal water rights. [1] On May 25, 2022, the Hopi Tribe in northern Arizona became the first tribe to have federal water rights quantified under the new Arizona law when Superior Court Special Master Susan Harris issued the first report and recommended water decree (“Final Report and Decree”). [2]

Does the first decision under Arizona’s new standard mark a watershed moment in Indian water rights law, or is the decision simply business as usual in the troubled relationship between the United States and Indian nations? Does the new Arizona standard guarantee the Hopi Tribe, and other Arizona tribes that follow, a right to more water, to less water, or the same quantity as would have been afforded under the federal standard established in 1963?

Arizona’s water fate is entwined with the six other states dependent on declining flows in the Colorado River basin as well as with the Indian tribes who have rights under federal and state laws to the same water. In addition to reaching a Tier II shortage in the Colorado River, uncertainty flows from the fact that thousands of water rights claims, large and small, to the use of water flowing in the Gila River basin and the Little Colorado River basin remain unresolved after decades of on-going litigation. [3]

The Little Colorado River has an average baseflow of 158,000 acre feet of water annually (“AFA”). The Hopi Tribe has requested on its own behalf rights to 70,698 AFA, an amount equal to roughly half of the baseflow of the Little Colorado River. [4] The United States, in its trust role for the Hopi Tribe, has requested 39,493 AFA. [5] The Special Master’s recommended decree is for 28,989 AFA. [6]

In 1908, the U.S. Supreme Court held that Indian tribes had implied water rights for all Congressionally-designated reservations for tribes, known as Winters rights, and that such water rights should be sufficient to fulfill the purpose of the reservation. [7] In 1963, the U.S. Supreme Court clarified the measure of these water rights in Arizona v. California. [8] The court held that tribes were entitled to “enough water” as necessary to irrigate the reservation’s “practicably irrigable acreage,” (“PIA”). [9] In the 2001 Gila V decision, the Arizona Supreme Court held that PIA was neither the proper nor the sole measure for tribes’ Winters rights. [10]

Arizona as well as most arid Southwestern states operate under a prior appropriation water rights system (“first-in-line, first-in-right”). Priority dates are established from the time that water is first diverted and put to beneficial use. Junior users, or later priority dates, absorb any water shortages. Therefore, older, or earlier, priority dates have immense value. Many tribes have early priority dates for their Winters rights based on the date of the establishment of their reservation. For many tribes, including the Hopi Tribe and Navajo Nation, this puts them at the front of the line, well ahead of Arizona statehood in 1912.

Under the McCarran Amendment, federal and tribal sovereignty is waived when a state adjudicates claims to state water in a comprehensive proceeding. [11] A general stream adjudication is comprehensive state litigation to determine the priority date, quantity, and type of use for water rights claims for all claimants within a river basin. The United States’ and Indian tribes’ water rights allocations are therefore determined under state law rather than federal law. Under Arizona state law, water rights are determined through prior appropriation rather than the riparian rule of reasonableness common in less arid eastern states. The riparian reasonableness rule is explicitly rejected in Arizona’s Constitution.

Two Arizona general stream adjudications originating in the 1970s will eventually settle all outstanding claims for the use of water in the Gila River basin and the Little Colorado River basin. A core challenge in these proceedings is that there are far more claims than available water. [12]

The Special Master’s Final Report and Decree is an impressive total of 408 pages, including 289 pages comprising the report and 119 pages of the recommended decree. The report contains 341 findings of fact and 76 conclusions of law in exacting detail. The report provides a detailed analysis of the non-exclusive factors identified by the Arizona Supreme Court in Gila V including tribal history and culture, geography, economic base, prior water use, and current and projected population. [13] The report is also a survey of Indian water law, citing many of the most significant cases.

The Final Report and Decree notes that the Hopi Tribe, the Navajo Nation, and the United States each object to aspects of the Gila V water quantification as a departure from federal law established by the U.S. Supreme Court. [14] However, the Apache County court is bound to follow the law as set by the Arizona Supreme Court. [15]

There are arguments pre-dating the Hopi Tribe’s adjudication that the Arizona standard in Gila V is consistent with U.S. Supreme Court precedent, [16] and arguments that the new standard conflicts with U.S. Supreme Court precedent. [17]

Gila V raises the issue of inequity in water allocation under the PIA standard based on geography. A central argument against PIA in the Gila V opinion is that PIA benefits tribes with large swaths of readily irrigable land in alluvial basins with fertile soil, and disadvantages tribes geographically located in mountainous terrain with nominal irrigable acreage. [18] The Court’s solution was to retain PIA as one element of measure, with the inclusion of more factors weighing in favor of tribes with nominal irrigable acreage within their boundaries. [19]

The Hopi Tribe, located in mountainous terrain in northern Arizona, is one such tribe with “practicably irrigable” acreage representing a relatively smaller percentage of its overall ancestral homeland. The Hopi Tribe should therefore benefit from a standard that includes more factors than PIA. On the other hand, the more nuanced and fact-intensive approach under Gila V means significantly higher costs of litigation for all parties. A fact-intensive inquiry means expert witnesses along with far more time and cost to litigants.

Objections to the Final Report and Decree must be filed by November 21, 2022. The Final Report and Decree and objections will then be heard by a Superior Court Judge for Apache County who will issue a final decision. With so much at stake, the Superior Court decision is likely to be appealed to the Arizona Supreme Court. A decision by that court may be petitioned for review by the U.S. Supreme Court, putting the divergent Arizona Indian water rights quantification method before the court that set the federal PIA standard.

Ultimately, the Special Master’s Final Report and Decree brings all parties in Arizona’s Little Colorado River General Stream Adjudication one step forward in a decades long dispute, perhaps a false plateau, with years of uncertainty still ahead. That much seems to be business as usual, while the relative quantity of water recommended for the Hopi Tribe under the Arizona standard remains an unanswerable question without an empirical comparison under PIA. What is certain is that the stresses on this precious and scarce resource, water, will continue to grow as the litigation flows forward in the years ahead.

Greg Esser (he/him) is an artist and 3L at the Arizona State University Sandra Day O’Connor College of Law. He graduated from Oberlin College with a B.A. in Art and Social Change. He also graduated from Arizona State University’s Herberger Institute for Design and the Arts with a M.F.A. degree in Intermedia. His legal work and research focuses on elder law issues including financial exploitation and white collar crime. Esser previously served as Desert Initiative Director for the ASU Art Museum.


† The term “Indian” is used herein in lieu of Native American or Indigenous following legal scholarship (both Native and non-Native), federal law and federal agency usage, and case law usage, with the explicit recognition that all such terms are imposed through a non-Native language upon colonized peoples. Such terms are not originally self-referential, nor terms of self-identification first used by the sovereign nations and individuals referenced by such terms. Cristoforo Colombo, who likely changed his own name when he immigrated from Italy to Spain, missed his intended geographic target by a lot, yet the term “Indian” has persisted in usage nevertheless.

[1] In re General Adjudication of All Rights to Use Water in Gila River System and Source, 35 P.3d 68 (Ariz. 2001) [hereinafter Gila V]; Arizona v. California, 373 U.S. 546 (1963) [hereinafter Arizona v. California I].

[2] Final Report and Recommended Decree, In re Gen. Adjudication of All Rts. to Use Water in the Little Colorado River Sys. & Source, In re Hopi Reservation HSR, CV 6417-203 (2022) [hereinafter Final Report and Decree].

[3] Rhett Larson & Brian Payne, Unclouding Arizona’s Water Future, 49 Ariz. St. L.J. 465 (2017).

[4] Final Report and Decree at 8.

[5] Id.

[6] Id. at 289.

[7] Winters v. United States, 207 U.S. 564 (1908).

[8] 373 U.S. at 595.

[9] Id. at 600-601.

[10] 35 P.3d at 79.

[11] 42 U.S.C § 666.

[12] Rhett Larson & Kelly Kennedy, Bankrupt Rivers, 49 U.C. Davis J. Int’l L. & Pol’y 1335 (2016)  (providing an overview of general stream adjudications and comparing the allocation of water claims that exceed supply to bankruptcy proceedings).

[13] 35 P.3rd at 79-81.

[14] Final Report and Decree at 26.

[15] Id.

[16] Barbara A. Cosens, The Measure of Indian Water Rights: The Arizona Homeland Standard, Gila River Adjudication, 42 Nat. Res. J. 835 (2002)  (“By articulating a homeland standard based on tribal economic development plans, cultural needs, and historic water uses, the Arizona Supreme Court has eliminated many of the blatant inequities plaguing the current approach to Indian water right quantification.”).

[17] Galen Lemei, Abandoning the PIA Standard: A Comment on Gila V, 9 Mich. J. Race & L. 235 (2003)  (“[O]pponents of broad Indian reserved water rights convinced the Arizona Supreme Court to abandon the PIA standard established by the U.S. Supreme Court for measuring and defining water rights for American Indians.”).

[18] 35 P.3d at 78.

[19] Id. at 79-81.