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16 water. Ibid. A contrary reading, the Court said, would “impair or defeat” the parties’ agreement. Id., at 577.

While Winters involved a claim brought by the United States, the federal government asserted “the rights of the Indians” themselves. Id., at 576. This Court’s subsequent cases have confirmed as much. In United States v. Powers, 305 U. S. 527 (1939), for instance, this Court cited Winters as authority for its holding that a different treaty impliedly “reserved” waters “for the equal benefit of tribal members.” Id., at 532 (emphasis added). So when the reservation was dissolved and the land allotted, “the right to use some portion of tribal waters essential for cultivation passed to the owners” of the individual plots of land. Ibid. (emphasis added). Later, in Arizona I, this Court described Winters as standing for the principle that “the Government, when it create[s an] Indian Reservation, intend[s] to deal fairly with the Indians by reserving for them the waters without which their lands would have been useless.” 373 U. S., at 600 (emphasis added). Congress would not “creat[e] an Indian Reservation without intending to reserve waters necessary to make the reservation livable.” Id., at 559.

Sometimes the United States may hold a Tribe’s water rights in trust. When it does, this Court has recognized, the United States must manage those water rights “[a]s a fiduciary,” Arizona v. California, 460 U. S. 605, 626–627 (1983) (Arizona II), one held to “the most exacting fiduciary standards,” Seminole Nation, 316 U. S., at 297. This is no special rule. “[F]iduciary duties characteristically attach to decisions” that involve “managing [the] assets and distributing [the] property” of others. Pegram v. Herdrich, 530 U. S. 211, 231 (2000). It follows, then, that a Tribe may bring an action in equity against the United States for “fail[ing] to provide an accurate accounting of” the water rights it holds on a Tribe’s behalf. United States v. Tohono O’odham Nation, 563 U. S. 307, 318 (2011). After all, it is black-letter law that a plaintiff may seek an accounting “whenever the