ARIZONA v. SAN CARLOS APACHE TRIBE

JUSTICE BRENNAN delivered the opinion of the Court.

These consolidated cases form a sequel to our decision in Colorado River Water Conservation District v. United States, 424 U.S. 800 (1976). That case held that (1) the McCarran Amendment, 66 Stat. 560, 43 U.S.C. § 666, which waived the sovereign immunity of the United States as to comprehensive state water rights adjudications, provides state courts with jurisdiction to adjudicate Indian water rights held in trust by the United States, and (2), in light of the clear federal policies underlying the McCarran Amendment, a water rights suit brought by the United States in federal court was properly dismissed in favor of a concurrent comprehensive adjudication reaching the same issues in Colorado state court. The questions in these cases are parallel: (1) What is the effect of the McCarran Amendment in those States which, unlike Colorado, were admitted to the Union subject to federal legislation that reserved "absolute jurisdiction and control" over Indian lands in the Congress of the United States? (2) If the courts of such States do have jurisdiction to adjudicate Indian water rights, should concurrent federal suits brought by Indian tribes, rather than by the United States, and raising only Indian claims, also be subject to dismissal under the doctrine of Colorado River?

The McCarran Amendment provides in relevant part:
"(a) Consent is hereby given to join the United States as a defendant in any suit (1) for the adjudication of rights to the use of water of a river system or other source, or (2) for the administration of such rights, where it appears that the United States is the owner of or is in the process of acquiring water rights by appropriation under State law, by purchase, by exchange, or otherwise, and the United States is a necessary party to such suit. The United States, when a party to any such suit, shall (1) be deemed to have waived any right to plead that the State laws are inapplicable or that the United States is not amenable thereto by reason of its sovereignty, and (2) shall be subject to the judgments, orders and decrees of the court having jurisdiction, and may obtain review thereof, in the same manner and to the same extent as a private individual under like circumstances . . . ."

I

Colorado River arose out of a suit brought by the Federal Government in the United States District Court for the District of Colorado seeking a declaration of its rights, and the rights of a number of Indian Tribes, to waters in certain rivers and their tributaries located in one of the drainage basins of the State of Colorado. In the suit, the Government asserted reserved rights, governed by federal law, as well as rights based on state law. Shortly after the federal suit was commenced, the United States was joined, pursuant to the McCarran Amendment, as a party in the ongoing state-court comprehensive water adjudication being conducted for the same drainage basin. The Federal District Court, on motion of certain of the defendants and intervenors, dismissed the federal suit, stating that the doctrine of abstention required deference to the state proceedings. The Court of Appeals reversed the District Court, and we in turn reversed the Court of Appeals.

See generally Arizona v. California, 373 U.S. 546 (1963); Winters v. United States, 207 U.S. 564 (1908).

We began our analysis in Colorado River by conceding that the District Court had jurisdiction over the federal suit under 28 U.S.C. § 1345, the general provision conferring district court jurisdiction over most civil actions brought by the Federal Government. We then examined whether the federal suit was nevertheless properly dismissed in view of the concurrent state-court proceedings. This part of the analysis began by considering "whether the McCarran Amendment provided consent to determine federal reserved rights held on behalf of Indians in state court," 424 U.S., at 809, since "given the claims for Indian water rights in [the federal suit], dismissal clearly would have been inappropriate if the state court had no jurisdiction to decide those claims." Ibid. We concluded:

"Not only the Amendment's language, but also its underlying policy, dictates a construction including Indian rights in its provisions. [ United States v. District Court for Eagle County, 401 U.S. 520 (1971),] rejected the conclusion that federal reserved rights in general were not reached by the Amendment for the reason that the Amendment `[deals] with an all-inclusive statute concerning "the adjudication of rights to the use of water of a river system."' Id., at 524. This consideration applies as well to federal water rights reserved for Indian reservations." Id., at 810.

In sum, considering the important federal interest in allowing all water rights on a river system to be adjudicated in a single comprehensive state proceedings, and "bearing in mind the ubiquitous nature of Indian water rights in the Southwest," it was clear to us "that a construction of the Amendment excluding those rights from its coverage would enervate the Amendment's objective." Id., at 811.

We buttressed this conclusion with an examination of the legislative history of the McCarran Amendment. We also noted:

"Mere subjection of Indian rights to legal challenge in state court . . . would no more imperil those rights than would a suit brought by the Government in district court for their declaration . . . . The Government has not abdicated any responsibility fully to defend Indian rights in state court, and Indian interests may be satisfactorily protected under regimes of state law. The Amendment in no way abridges any substantive claim on behalf of Indians under the doctrine of reserved rights. Moreover, as Eagle County said, `questions [arising from the collision of private rights and reserved rights of the United States], including the volume and scope of particular reserved rights, are federal questions which, if preserved, can be reviewed [by the Supreme Court] after final judgment by the Colorado court.' 401 U.S., at 526." Id., at 812-813 (citations omitted).

We then considered the dismissal itself. We found that the dismissal could not be supported under the doctrine of abstention in any of its forms, but that it was justified as an application of traditional principles of "`[w]ise judicial administration, giving regard to conservation of judicial resources and comprehensive disposition of litigation.'" Id., at 817, quoting Kerotest Mfg. Co. v. C-O-Two Fire Equipment Co., 342 U.S. 180, 183 (1952). We stated that, although the federal courts had a "virtually unflagging obligation . . . to exercise the jurisdiction given them," 424 U.S., at 817, there were certain very limited circumstances outside the abstention context in which dismissal was warranted in deference to a concurrent state-court suit. See generally id., at 817-819; Moses H. Cone Hospital v. Mercury Construction Corp., 460 U.S. 1, 13-19 (1983). In the case at hand, we noted the comprehensive nature of the state proceedings and the considerable expertise and technical resources available in those proceedings, 424 U.S., at 819-820. We concluded:

"[A] number of factors clearly counsel against concurrent federal proceedings. The most important of these is the McCarran Amendment itself. The clear federal policy evinced by that legislation is the avoidance of piecemeal adjudication of water rights in a river system. This policy is akin to that underlying the rule requiring that jurisdiction be yielded to the court first acquiring control of property, for the concern in such instances is with avoiding the generation of additional litigation through permitting inconsistent dispositions of property. This concern is heightened with respect to water rights, the relationships among which are highly interdependent. Indeed, we have recognized that actions seeking the allocation of water essentially involve the disposition of property and are best conducted in unified proceedings. The consent to jurisdiction given by the McCarran Amendment bespeaks a policy that recognizes the availability of comprehensive state systems for adjudication of water rights as the means for achieving these goals." Id., at 819 (citations omitted).

For these reasons, and others, we affirmed the judgment of the District Court dismissing the federal complaint.

The other factors were the apparent absence at the time of dismissal of any proceedings in the District Court other than the filing of the complaint, the extensive involvement of state water rights in the suit, the 300-mile distance between the Federal District Court in Denver and the state tribunal, and the Government's apparent willingness to participate in other comprehensive water proceedings in the state courts.

II

The two petitions considered here arise out of three separate consolidated appeals that were decided within three days of each other by the same panel of the Court of Appeals for the Ninth Circuit. In each of the underlying cases, either the United States as trustee or certain Indian Tribes on their own behalf, or both, asserted the right to have certain Indian water rights in Arizona or Montana adjudicated in federal court.

The Montana Cases (No. 81-2188)

In January 1975, the Northern Cheyenne Tribe brought an action in the United States District Court for the District of Montana seeking an adjudication of its rights in certain streams in that State. Shortly thereafter, the United States brought two suits in the same court, seeking a determination of water rights both on its own behalf and on behalf of a number of Indian Tribes, including the Northern Cheyenne, in the same streams. Each of the federal actions was a general adjudication which sought to determine the rights inter sese of all users of the stream, and not merely the rights of the plaintiffs. On motion of the Northern Cheyenne, its action was consolidated with one of the Government actions. The other concerned Tribes intervened as appropriate.

At about the time that all this activity was taking place in federal court, the State of Montana was preparing to begin a process of comprehensive water adjudication under a recently passed state statute. In July 1975, the Montana Department of Natural Resources and Conservation filed petitions in state court commencing comprehensive proceedings to adjudicate water rights in the same streams at issue in the federal cases.

Both sets of contestants having positioned themselves, nothing much happened for a number of years. The federal proceedings were stayed for a time pending our decision in Colorado River. When that decision came down, the State of Montana, one of the defendants in the federal suits, brought a motion to dismiss, which was argued in 1976, but not decided until 1979. Meanwhile, process was completed in the various suits, answers were submitted, and discovery commenced. Over in the state courts, events moved even more slowly, and no appreciable progress seems to have been made by 1979.

In April 1979, the United States brought four more suits in federal court, seeking to adjudicate its rights and the rights of various Indian Tribes in other Montana streams. One month later, the Montana Legislature amended its water adjudication procedures "to expedite and facilitate the adjudication of existing water rights." Act to Adjudicate Claims of Existing Water Rights in Montana, Ch. 697, § 1(1), 1979 Mont. Laws 1901. The legislation provided for the initiation of comprehensive proceedings by order of the Montana Supreme Court, the appointment of water judges throughout the State, and the consolidation of all existing actions within each water division. It also provided, among other things, that the Montana Supreme Court should issue an order requiring all claimants not already involved in the state proceedings, including the United States on its own behalf or as trustee for the Indians, to file a statement of claim with the Department of Natural Resources and Conservation by a date set by the court or be deemed to have abandoned any water rights claim. § 16, 1979 Mont. Laws 1906-1907, codified at Mont. Code Ann. § 85-2-212 (1981). The Montana court issued the required order, and the United States was served with formal notice thereof.

The statute required that the filing period established by the Montana Supreme Court be no less than one year, and that it be subject to extension, but not beyond June 30, 1983. Mont. Code Ann. § 85-2-212(2) (1981). In 1981, the statute was amended to exempt from the filing deadline Indian claims being negotiated with the Montana Reserved Water Rights Compact Commission. Ch. 268, § 4, 1981 Mont. Laws 393, codified at Mont. Code Ann. § 85-2-217 (1981).

The Montana Supreme Court set an original filing deadline of January 1, 1982, App. to Pet. for Cert. in No. 81-2188, pp. 138-139, and then extended the deadline to April 30, 1982, id., at 140-141. The United States apparently made protective filings by the deadline on behalf of all the Montana Tribes. Brief for Petitioners in No. 81-2188, p. 32. Two of the Indian Tribes apparently filed statements of claim of their own, and five apparently are negotiating with the Montana Reserved Water Rights Compact Commission, see n. 4, supra.

In November 1979, the two judges for the District of Montana jointly considered the motions to dismiss in each of the federal actions, and granted each of them. Northern Cheyenne Tribe of Northern Cheyenne Indian Reservation v. Tongue River Water Users Assn., 484 F. Supp. 31. The court relied strongly on the new Montana legislation, stating:

See generally C. Wright, Law of Federal Courts 9 (4th ed. 1983).

"The above-cited sections reflect both the policy and the essential mechanism for adjudication of state water rights. Adjudication by adversary proceeding initiated by one claimant against all others in his drainage has been forsaken in favor of blanket adjudication of all claims, including federal and federal trust claims . . . . It is clear that the adjudication contemplated by the [1979 legislation] is both comprehensive and efficient. As the general adjudication has been initiated by recent order of the Montana Supreme Court, it would seem that the greater wisdom lies in following Colorado River, and, on the basis of wise judicial administration, deferring to the comprehensive state proceedings." Id., at 35-36.

The District Court also noted, among other things, that the federal proceedings "are all in their infancy; service of process has been but recently completed," id., at 36, that the state forums were geographically more convenient to the parties, that "[t]he amount of time contemplated for completion of the state adjudication is significantly less than would be necessary for federal adjudication, insofar as the state has provided a special court system solely devoted to water rights adjudication," ibid., and that "[t]he possibility of conflicting adjudications by the concurrent forums . . . looms large and could be partially avoided only by staying the pending state adjudication, an action Colorado River has intimated is distinctly repugnant to a clear state policy and purpose." Ibid.

On appeal, a divided Court of Appeals reversed. Northern Cheyenne Tribe of Northern Cheyenne Indian Reservation v. Adsit, 668 F.2d 1080 (CA9 1982). First, it held that Montana, unlike Colorado, might well lack jurisdiction to adjudicate Indian claims in state court. The court reached this conclusion on the basis of two closely linked documents: the Enabling Act under which Montana was admitted to statehood, and the Montana Constitution promulgated in response to that Enabling Act, both of which provide, in identical terms, that the people inhabiting Montana

"agree and declare that they forever disclaim all right and title to . . . all lands . . . owned or held by any Indian or Indian tribes; and that until the title thereto shall have been extinguished by the United States, the same shall be and remain subject to the disposition of the United States, and said Indian lands shall remain under the absolute jurisdiction and control of the Congress of the United States . . . ." Enabling Act of Feb. 22, 1889, § 4, 25 Stat. 677 (North Dakota, South Dakota, Montana, and Washington); Mont. Const., Ordinance No. I (1895).

The Court of Appeals concluded that, by their terms, the Enabling Act and constitutional disclaimer prohibit Montana from exercising even adjudicatory jurisdiction over Indian water rights, and that the McCarran Amendment effected no change in that disability. It also held, however, that the State might have acquired such jurisdiction under Pub.L. 280, 67 Stat. 588, which, from 1953 until its amendment in 1968, allowed any State that wished to do so to acquire certain aspects of civil and criminal jurisdiction over Indian affairs, and authorized States with constitutional or statutory disclaimers to "amend, where necessary, their State constitution or existing statutes, as the case may be, to remove any legal impediment" to the assumption of such jurisdiction. § 6, 67 Stat. 590. See generally Washington v. Yakima Indian Nation, 439 U.S. 463 (1979). The court did not decide whether Montana had amended its Constitution in accordance with the requirements of Pub.L. 280, cf. Yakima Indian Nation, supra, at 478-493, but it criticized the District Court for not undertaking such an analysis.

The second, and dispositive, ground of decision in the Court of Appeals, however, was its conclusion that "[e]ven if we were to find that Montana had validly repealed the disclaimer language in its constitution, . . . [t]he limited factual circumstances of [Colorado River] prevent its application to the Montana litigation." 668 F.2d, at 1087. In reaching this conclusion, the court relied in part on the infancy of both the federal and state proceedings in the Montana litigation, the possible inadequacy of the state proceedings (which it did not discuss in great detail), and the fact that the Indians (who could not be joined involuntarily in the state proceedings) might not be adequately represented by the United States in state court in light of conflicts of interest between the Federal Government's responsibilities as trustee and its own claims to water.

The Arizona Cases (No. 81-2147)

In the mid-1970's, various water rights claimants in Arizona filed petitions in state court to initiate general adjudications to determine conflicting rights in a number of river systems. In early 1979, process was served in one of the proceedings on approximately 12,000 known potential water claimants, including the United States. In July 1981, process was served in another proceeding on approximately 58,000 known water claimants, again including the United States. In each case, the United States was joined both in its independent capacity and as trustee for various Indian Tribes.

In March and April 1979, a number of Indian Tribes whose rights were implicated by the state water proceedings filed a series of suits in the United States District Court for the District of Arizona, asking variously for removal of the state adjudications to federal court, declaratory and injunctive relief preventing any further adjudication of their rights in state court, and independent federal determinations of their water rights. A number of defendants in the federal proceedings filed motions seeking remand or dismissal. The District Court, relying on Colorado River, remanded the removed actions, and dismissed most of the independent federal actions without prejudice. In re Determination of Conflicting Rights to Use of Water from Salt River Above Granite Reef Dam, 484 F. Supp. 778 (1980). It stayed one of the remaining actions pending the completion of state proceedings. App. to Pet. for Cert. in No. 81-2147, p. D-1.

Two of the actions are in abeyance, apparently pending completion of service of process.

The Tribes appealed from these decisions, with the exception of the remand orders. The Court of Appeals reversed, holding that the Enabling Act under which Arizona was admitted to statehood, 36 Stat. 557, and the Arizona Constitution, Art. 20, ¶ 4, both of which contain wording substantially identical to the Montana Enabling Act and Constitution, disabled Arizona from adjudicating Indian water claims. San Carlos Apache Tribe v. Arizona, 668 F.2d 1093 (CA9 1982); Navajo Nation v. United States, 668 F.2d 1100 (CA9 1982). The court remanded to the District Court to determine whether Arizona nevertheless "properly asserted jurisdiction pursuant to Public Law 280." 668 F.2d, at 1098; see 668 F.2d, at 1102. The court did not decide whether, if the State had properly asserted jurisdiction, dismissal would have been proper under Colorado River, except to note that "the district judge did not make findings on this issue and the record indicates significant differences between these cases and [Colorado River]." 668 F.2d, at 1098; see 668 F.2d, at 1102.

The stay order was certified for interlocutory appeal under 28 U.S.C. § 1292(b). See also Moses H. Cone Hospital v. Mercury Construction Corp., 460 U.S. 1, 8-13 (1983) (upholding appealability of similar stay order under 28 U.S.C. § 1291).

We granted certiorari, 459 U.S. 821 (1982), in order to resolve a conflict among the Circuits regarding the role of federal and state courts in adjudicating Indian water rights. We now reverse.

In Jicarilla Apache Tribe v. United States, 601 F.2d 1116 (1979), the Court of Appeals for the Tenth Circuit held that the Enabling Act under which New Mexico was admitted to the Union (whose language is essentially the same as the Enabling Acts at issue in these cases) did not bar state jurisdiction over Indian water rights, and upheld the District Court's dismissal of a general water adjudication suit brought in federal court by the Jicarilla Apache Tribe.

III A

At the outset of our analysis, a number of propositions are clear. First, the federal courts had jurisdiction here to hear the suits brought both by the United States and the Indian Tribes. Second, it is also clear in these cases, as it was in Colorado River, that a dismissal or stay of the federal suits would have been improper if there was no jurisdiction in the concurrent state actions to adjudicate the claims at issue in the federal suits. 424 U.S., at 800. Third, the parties here agree that the Court of Appeals erred in believing that, in the absence of state jurisdiction otherwise, Pub.L. 280 would have authorized the States to assume jurisdiction over the adjudication of Indian water rights. To the contrary, Pub.L. 280 specifically withheld from state courts jurisdiction to adjudicate ownership or right to possession "of any real or personal property, including water rights, belonging to any Indian or any Indian tribe, band, or community that is held in trust by the United States or is subject to a restriction against alienation imposed by the United States." 28 U.S.C. § 1360(b) (emphasis added). Thus, the presence or absence of jurisdiction must rise or fall without reference to whether the States have assumed jurisdiction under Pub.L. 280.

The primary ground of jurisdiction for the suits brought by the United States is 28 U.S.C. § 1345. The primary ground of jurisdiction for the suits brought by the Indians is 28 U.S.C. § 1362, which provides in relevant part: "The district courts shall have original jurisdiction of all civil actions, brought by any Indian tribe . . . wherein the matter in controversy arises under the Constitution, laws, or treaties of the United States." Section 1362 was passed in 1966 in order to give Indian tribes access to federal court on federal issues without regard to the $10,000 amount-in-controversy requirement then included in 28 U.S.C. § 1331, the general federal-question jurisdictional statute. Congress contemplated that § 1362 would be used particularly in situations in which the United States suffered from a conflict of interest or was otherwise unable or unwilling to bring suit as trustee for the Indians, and its passage reflected a congressional policy against relegating Indians to state court when an identical suit brought on their behalf by the United States could have been heard in federal court. See S. Rep. No. 1507, 89th Cong., 2d Sess., 2-3 (1966); H.R. Rep. No. 2040, 89th Cong., 2d Sess., 2, 4 (1966). Just as the McCarran Amendment did not do away with federal jurisdiction over water rights claims brought under § 1345, Colorado River Water Conservation District v. United States, 424 U.S. 800, 806-809 (1976), there is no reason to think that it limits the jurisdictional reach of § 1362.

As we explained in Colorado River, however, these provisions "only qualif[y] the import of the general consent to state jurisdiction given by [Pub.L. 280, and] . . . [do] not purport to limit the special consent to jurisdiction given by the McCarran Amendment." 424 U.S., at 812-813, n. 20.

Finally, it should be obvious that, to the extent that a claimed bar to state jurisdiction in these cases is premised on the respective State Constitutions, that is a question of state law over which the state courts have binding authority. Because, in each of these cases, the state courts have taken jurisdiction over the Indian water rights at issue here, we must assume, until informed otherwise, that — at least insofar as state law is concerned — such jurisdiction exists. We must therefore look, for our purposes, to the federal Enabling Acts and other federal legislation, in order to determine whether there is a federal bar to the assertion of state jurisdiction in these cases.

B

That we were not required in Colorado River to interpret the McCarran Amendment in light of any statehood Enabling Act was largely a matter of fortuity, for Colorado is one of the few Western States that were not admitted to the Union pursuant to an Enabling Act containing substantially the same language as is found in the Arizona and Montana Enabling Acts. Indeed, a substantial majority of Indian land — including most of the largest Indian reservations — lies in States subject to such Enabling Acts. Moreover, the reason that Colorado was not subject to such an Enabling Act, and Arizona and Montana were, has more to do with historical timing than with deliberate congressional selection. Colorado was admitted to the Union in 1876. In 1882, this Court held in United States v. McBratney, 104 U.S. 621, that the federal courts in Colorado had no criminal jurisdiction in a murder committed by one non-Indian against another on an Indian reservation, pointing out that the case did not concern "the punishment of crimes committed by or against Indians, the protection of the Indians in their improvements, or the regulation by Congress of the alienation and descent of property and the government and internal police of the Indians." Id., at 624. We also suggested, however, that the result might have been different if Congress had expressly reserved all criminal jurisdiction on Indian reservations when Colorado was admitted to the Union, pointing to a similar disclaimer contained in the legislation by which Kansas was admitted to statehood in 1861. Id., at 623-624; see The Kansas Indians, 5 Wall. 737 (1867). Probably in response to the McBratney decision, Congress resumed the practice of including reservations in Enabling Acts, and did so in the case of virtually every State admitted after 1882. See n. 12, supra.

See Enabling Act of Feb. 22, 1889, § 4, 25 Stat. 676-677 (North Dakota, South Dakota, Montana, and Washington); Enabling Act of July 16, 1894, § 3, 28 Stat. 108 (Utah); Enabling Act of June 16, 1906, § 3, 34 Stat. 270 (Oklahoma); Enabling Act of June 20, 1910, §§ 2, 20, 36 Stat. 558-559, 569 (New Mexico and Arizona); Enabling Act of July 7, 1958, § 4, 72 Stat. 339, as amended by Pub.L. 86-70, § 2(a), 73 Stat. 141 (Alaska). Idaho and Wyoming, which were both admitted to statehood in 1890 without prior Enabling Acts, nevertheless inserted disclaimers in their State Constitutions. See Idaho Const., Art. 21, § 19; Wyo. Const., Art. 21, § 26.

See Brief for United States 12, and sources cited.

Despite McBratney and The Kansas Indians, the presence or absence of specific jurisdictional disclaimers has rarely been dispositive in our consideration of state jurisdiction over Indian affairs or activities on Indian lands. In Draper v. United States, 164 U.S. 240 (1896), for example, this Court held that, despite the jurisdictional reservation in the Montana Enabling Act, a federal court still did not have jurisdiction over a crime committed on an Indian reservation by one non-Indian against another. We stated:

"As equality of statehood is the rule, the words relied on here to create an exception cannot be construed as doing so, if, by any reasonable meaning, they can be otherwise treated. The mere reservation of jurisdiction and control by the United States of `Indian lands' does not of necessity signify a retention of jurisdiction in the United States to punish all offences committed on such lands by others than Indians or against Indians." Id., at 244-245.

Similarly, in Organized Village of Kake v. Egan, 369 U.S. 60 (1962), we held that a reservation in the Alaska Enabling Act did not deprive the State of the right to regulate Indian fishing licensed by the Department of the Interior, finding that the state regulation neither interfered with Indian self-government nor impaired any right granted or reserved by federal law. Conversely, Worcester v. Georgia, 6 Pet. 515 (1832), perhaps the most expansive declaration of Indian independence from state regulation ever uttered by this Court, pertained to one of the original 13 States, unbound by any Enabling Act whatsoever. See also, e.g., The New York Indians, 5 Wall. 761, 769-770 (1867) (reaching same conclusion as The Kansas Indians, supra, but without benefit of disclaimer). And our many recent decisions recognizing crucial limits on the power of the States to regulate Indian affairs have rarely either invoked reservations of jurisdiction contained in statehood Enabling Acts by anything more than a passing mention or distinguished between disclaimer States and nondisclaimer States. See, e.g., New Mexico v. Mescalero Apache Tribe, 462 U.S. 324 (1983); Ramah Navajo School Board v. Bureau of Revenue, 458 U.S. 832 (1982); White Mountain Apache Tribe v. Bracker, 448 U.S. 136 (1980); Bryan v. Itasca County, 426 U.S. 373 (1976); Williams v. Lee, 358 U.S. 217 (1959).

In light of this history, the parties in these cases have engaged in a vigorous debate as to the exact meaning and significance of the Arizona and Montana Enabling Acts. We need not resolve that debate, however, nor need we resort to the more general doctrines that have developed to chart the limits of state authority over Indians, because we are convinced that, whatever limitation the Enabling Acts or federal policy may have originally placed on state-court jurisdiction over Indian water rights, those limitations were removed by the McCarran Amendment. Cf. Washington v. Yakima Indian Nation, 439 U.S., at 484-493. Congress clearly would have had the right to distinguish between disclaimer and nondisclaimer States in passing the McCarran Amendment. But the Amendment was designed to deal with a general problem arising out of the limitations that federal sovereign immunity placed on the ability of the States to adjudicate water rights, and nowhere in its text or legislative history do we find any indication that Congress intended the efficacy of the remedy to differ from one State to another. Moreover, we stated in Colorado River that "bearing in mind the ubiquitous nature of Indian water rights in the Southwest, it is clear that a construction of the Amendment excluding those rights from its coverage would enervate the Amendment's objective." 424 U.S., at 811. The "ubiquitous nature of Indian water rights" is most apparent in the very States to which Congress attached jurisdictional reservations. See supra, at 561. To declare now that our holding in Colorado River applies only to that minority of Indian water claims located in States without jurisdictional reservations would constitute a curious and unwarranted retreat from the rationale behind our previous holding, and would work the very mischief that our decision in Colorado River sought to avoid. We need not rely on the possibly overbroad statement in Draper v. United States that "equality of statehood is the rule," 164 U.S., at 244, in order to conclude that, in this context at least, "equality of statehood" is sensible, necessary, and, most important, consistent with the will of Congress.

The United States, alone among the respondents, agrees that, in light of the McCarran Amendment, the Enabling Acts at issue here do not pose an obstacle to state jurisdiction to adjudicate Indian water rights. Brief for United States 11-15.

Because we do not construe the original meaning of the Enabling Acts, we also have no occasion to decide (assuming the relevance of the Acts in the first place) whether the McCarran Amendment's grant of permission to the States to adjudicate Indian water rights was effected by a partial repeal of the Enabling Acts, or by an exercise of the very power reserved to Congress under those Acts.

IV

The second crucial issue in these cases is whether our analysis in Colorado River applies with full force to federal suits brought by Indian tribes, rather than by the United States, and seeking adjudication only of Indian water rights. This question is not directly answered by Colorado River, because we specifically reserved in that case "[w]hether similar considerations would permit dismissal of a water suit brought by a private party in federal district court." 424 U.S., at 820, n. 26. On reflection, however, we must agree with JUSTICE STEVENS, who, in dissenting from our decision, wrote: "[T]he Federal Government surely has no lesser right of access to the federal forum than does a private [party], such as an Indian asserting his own claim. If this be so, today's holding will necessarily restrict the access to federal court of private plaintiffs asserting water rights claims in Colorado." Id., at 827.

As is apparent from our discussion of the facts, supra, at 553-558, some of the cases now before us are suits brought by the United States. In light of our express holding in Colorado River, what we say here with regard to the suits brought by the Indians must apply a fortiori to the suits brought by the United States. In addition, some of the cases before us sought adjudication of all the rights to a particular water system, rather than merely Indian or other federal water rights, and it is argued that these suits avoid the "piecemeal adjudication of water rights" which we found in Colorado River to be inconsistent with federal policy. 424 U.S., at 819. See, e.g., Brief for Respondents Assiniboine and Sioux Tribes et al. 25-29. Given, however, that one of the best arguments in favor of retaining federal jurisdiction in Indian water cases is that Indian water rights can be adjudicated separately and then incorporated into the results of the comprehensive state proceedings, see infra, at 567, the proper analysis of the more ambitious federal suits at issue here must also follow a fortiori from our discussion in text. A comprehensive federal adjudication going on at the same time as a comprehensive state adjudication might not literally be "piecemeal." It is, however, duplicative, wasteful, inconsistent with the McCarran Amendment's policy of "recogniz[ing] the availability of comprehensive state systems for adjudication of water rights as the means for [conducting unified water rights proceedings]," 424 U.S., at 819, likely to "generat[e] . . . additional litigation" as a result of "inconsistent dispositions of property," ibid., and permeated with state-law issues entirely tangential to any conceivable federal interest, see id., at 820; cf. Moses H. Cone Hospital, 460 U.S., at 19-26.

The United States and the various Indian respondents raise a series of arguments why dismissal or stay of the federal suit is not appropriate when it is brought by an Indian tribe and only seeks to adjudicate Indian rights. (1) Indian rights have traditionally been left free of interference from the States. (2) State courts may be inhospitable to Indian rights. (3) The McCarran Amendment, although it waived United States sovereign immunity in state comprehensive water adjudications, did not waive Indian sovereign immunity. It is therefore unfair to force Indian claimants to choose between waiving their sovereign immunity by intervening in the state proceedings and relying on the United States to represent their interests in state court, particularly in light of the frequent conflict of interest between Indian claims and other federal interests and the right of the Indians under 28 U.S.C. § 1362 to bring suit on their own behalf in federal court. (4) Indian water rights claims are generally based on federal rather than state law. (5) Because Indian water claims are based on the doctrine of "reserved rights," and take priority over most water rights created by state law, they need not as a practical matter be adjudicated inter sese with other water rights, and could simply be incorporated into the comprehensive state decree at the conclusion of the state proceedings.

This argument, of course, suffers from the flaw that, although the McCarran Amendment did not waive the sovereign immunity of Indians as parties to state comprehensive water adjudications, it did (as we made quite clear in Colorado River) waive sovereign immunity with regard to the Indian rights at issue in those proceedings. Moreover, contrary to the submissions by certain of the parties, any judgment against the United States, as trustee for the Indians, would ordinarily be binding on the Indians. In addition, there is no indication in these cases that the state courts would deny the Indian parties leave to intervene to protect their interests. Thus, although the Indians have the right to refuse to intervene even if they believe that the United States is not adequately representing their interests, the practical value of that right in this context is dubious at best.

Each of these arguments has a good deal of force. We note, though, that very similar arguments were raised and rejected in United States v. District Court for Eagle County, 401 U.S. 520 (1971), and Colorado River. More important, all of these arguments founder on one crucial fact: If the state proceedings have jurisdiction over the Indian water rights at issue here, as appears to be the case, then concurrent federal proceedings are likely to be duplicative and wasteful, generating "additional litigation through permitting inconsistent dispositions of property." Colorado River, 424 U.S., at 819. Moreover, since a judgment by either court would ordinarily be res judicata in the other, the existence of such concurrent proceedings creates the serious potential for spawning an unseemly and destructive race to see which forum can resolve the same issues first — a race contrary to the entire spirit of the McCarran Amendment and prejudicial to say the least, to the possibility of reasoned decisionmaking by either forum. The United States and many of the Indian Tribes recognize these concerns, but in responding to them they cast aside the sort of sound argument generally apparent in the rest of their submissions and rely instead on vague statements of faith and hope. The United States, for example, states that adjudicating Indian water rights in federal court, despite the existence of a comprehensive state proceeding, would not

See, e.g., Brief for United States in United States v. District Court for Eagle County, O. T. 1970, No. 87, p. 19 ("excluding reserved water rights of the United States from State adjudication proceedings would not produce the `undesirable, impractical and chaotic situation' that the Colorado Supreme Court envisioned); Brief for United States in Colorado River Conservation District v. United States, O. T. 1975, No. 74-940, p. 33 (federal suit brought by United States involves only questions of federal law); pp. 35-36 (federal forum necessary to avoid "local prejudice"); pp. 43-44 (federal adjudication of Indian water rights can be incorporated into comprehensive state proceedings); p. 50 (separate proceedings practical, as long as all determinations are ultimately integrated); pp. 53-54 (construing McCarran Amendment to grant States jurisdiction to adjudicate Indian water rights would ignore "unique legal status of Indian property").

But cf. n. 20, infra.

"entail any duplication or potential for inconsistent judgments. The federal court will quantify the Indian rights only if it is asked to do so before the State court has embarked on the task. And, of course, once the United States district court has indicated its determination to perform that limited role, we assume the State tribunal will turn its attention to the typically more complex business of adjudicating all other claims on the stream. In the usual case, the federal court will have completed its function earlier and its quantification of Indian water rights will simply be incorporated in the comprehensive State court decree." Brief for United States 30 (emphasis added).

Similarly, the Navajo Nation states:

"There is no reasonably foreseeable danger that [the] federal action [brought by the Navajo] will duplicate or delay state proceedings or waste judicial resources. While the Navajo claim proceeds in federal court, the state court can move forward to assess, quantify, and rank the 58,000 state claims. The Navajo federal action will be concluded long before the state court has finished its task." Brief for Respondent Navajo Nation in No. 81-2147, p. 22 (emphasis added; footnote omitted).

The problem with these scenarios, however, is that they assume a cooperative attitude on the part of state courts, state legislatures, and state parties which is neither legally required nor realistically always to be expected. The state courts need not "turn their attention" to other matters if they are prompted by state parties to adjudicate the Indian claims first. Moreover, considering the specialized resources and experience of the state courts, it is not at all obvious that the federal actions "will be concluded long before" the state courts have issued at least preliminary judgments on the question of Indian water rights. Cf. 484 F. Supp., at 36.

The McCarran Amendment, as interpreted in Colorado River, allows and encourages state courts to undertake the task of quantifying Indian water rights in the course of comprehensive water adjudications. Although adjudication of those rights in federal court instead might in the abstract be practical, and even wise, it will be neither practical nor wise as long as it creates the possibility of duplicative litigation, tension and controversy between the federal and state forums, hurried and pressured decisionmaking, and confusion over the disposition of property rights.

Colorado River, of course, does not require that a federal water suit must always be dismissed or stayed in deference to a concurrent and adequate comprehensive state adjudication. Certainly, the federal courts need not defer to the state proceedings if the state courts expressly agree to stay their own consideration of the issues raised in the federal action pending disposition of that action. Moreover, it may be in a particular case that, at the time a motion to dismiss is filed, the federal suit at issue is well enough along that its dismissal would itself constitute a waste of judicial resources and an invitation to duplicative effort. See Colorado River, supra, at 820; Moses H. Cone Hospital, 460 U.S., at 21-22. Finally, we do not deny that, in a case in which the arguments for and against deference to the state adjudication were otherwise closely matched, the fact that a federal suit was brought by Indians on their own behalf and sought only to adjudicate Indian rights should be figured into the balance. But the most important consideration in Colorado River, and the most important consideration in any federal water suit concurrent to a comprehensive state proceeding, must be the "policy underlying the McCarran Amendment," 424 U.S., at 820; see Moses H. Cone Hospital, supra, at 16, and, despite the strong arguments raised by the respondents, we cannot conclude that water rights suits brought by Indians and seeking adjudication only of Indian rights should be excepted from the application of that policy or from the general principles set out in Colorado River. In the cases before us, assuming that the state adjudications are adequate to quantify the rights at issue in the federal suits, and taking into account the McCarran Amendment policies we have just discussed, the expertise and administrative machinery available to the state courts, the infancy of the federal suits, the general judicial bias against piecemeal litigation, and the convenience to the parties, we must conclude that the District Courts were correct in deferring to the state proceedings.

In a number of these cases, respondents have raised challenges, not yet addressed either by the Court of Appeals or in this opinion, to the jurisdiction or adequacy of the particular state proceeding at issue to adjudicate some or all of the rights asserted in the federal suit. These challenges remain open for consideration on remand. Moreover, the courts below should, if the need arises, allow whatever amendment of pleadings not prejudicial to other parties may be necessary to preserve in federal court those issues as to which the state forum lacks jurisdiction or is inadequate.

We leave open for determination on remand whether the proper course in such cases is a stay of the federal suit or dismissal without prejudice. See Moses H. Cone Hospital, 460 U.S., at 28 (reserving issue). In either event, resort to the federal forum should remain available if warranted by a significant change of circumstances, such as, for example, a decision by a state court that it does not have jurisdiction over some or all of these claims after all.

V

Nothing we say today should be understood to represent even the slightest retreat from the general proposition we expressed so recently in New Mexico v. Mescalero Apache Tribe, 462 U.S., at 332: "Because of their sovereign status, [Indian] tribes and their reservation lands are insulated in some respects by a `historic immunity from state and local control,' Mescalero Apache Tribe v. Jones, [ 411 U.S. 145, 152 (1973)], and tribes retain any aspect of their historical sovereignty not `inconsistent with the overriding interests of the National Government.' Washington v. Confederated Tribes, [ 447 U.S. 134, 153 (1980)]." Nor should we be understood to retreat from the general proposition, expressed in Colorado River, that federal courts have a "virtually unflagging obligation . . . to exercise the jurisdiction given them." 424 U.S., at 817. See generally Moses H. Cone Hospital, supra, at 13-16. But water rights adjudication is a virtually unique type of proceeding, and the McCarran Amendment is a virtually unique federal statute, and we cannot in this context be guided by general propositions.

We also emphasize, as we did in Colorado River, that our decision in no way changes the substantive law by which Indian rights in state water adjudications must be judged. State courts, as much as federal courts, have a solemn obligation to follow federal law. Moreover, any state-court decision alleged to abridge Indian water rights protected by federal law can expect to receive, if brought for review before this Court, a particularized and exacting scrutiny commensurate with the powerful federal interest in safeguarding those rights from state encroachment.

The judgment of the Court of Appeals in each of these cases is reversed, and the cases are remanded for further proceedings consistent with this opinion. So ordered.

The motion of the Blackfeet Indian Tribe, filed March 22, 1983, to suspend all proceedings in this Court respecting the water rights of the Blackfeet Indian Tribe, Browning, Mont., and to preclude the Solicitor General or any other attorney of the Department of Justice from purporting to represent that Tribe in these proceedings is denied. The motion of the White Mountain Apache Tribe and the Blackfeet Indian Tribe, filed June 3, 1983, for leave to file a motion to dismiss for lack of in personam and subject-matter jurisdiction in this Court over the state-court water rights adjudication proceedings is denied. Treating the papers whereon the motion filed June 3, 1983, was submitted as a motion for leave to file a brief amicus curiae, and treating the accompanying papers as a brief amicus curiae, leave to file the brief is granted.