The question presented in this litigation is whether the reservation of Devil's Hole as a national monument reserved federal water rights in unappropriated water.

Devil's Hole is a deep limestone cavern in Nevada. Approximately 50 feet below the opening of the cavern is a pool 65 feet long, 10 feet wide, and at least 200 feet deep, although its actual depth is unknown. The pool is a remnant of the prehistoric Death Valley Lake System and is situated on land owned by the United States since the Treaty of Guadalupe Hidalgo in 1848, 9 Stat. 922. By the Proclamation of January 17, 1952, President Truman withdrew from the public domain a 40-acre tract of land surrounding Devil's Hole, making it a detached component of the Death Valley National Monument. Proclamation No. 2961, 3 CFR 147 (1949-1953 Comp.).1 The Proclamation was issued under the American Antiquities Preservation Act, 34 Stat. 225, 16 U.S.C. § 431, which authorizes the President to declare as national monuments "objects of historic or scientific interest that are situated upon the lands owned or controlled by the Government of the United States . . .."

The 1952 Proclamation notes that Death Valley was set aside as a national monument "for the preservation of the unusual features of scenic, scientific, and educational interest therein contained." The Proclamation also notes that Devil's Hole is near Death Valley and contains a "remarkable underground pool." Additional preambulary statements in the Proclamation explain why Devil's Hole was being added to the Death Valley National Monument:

"WHEREAS the said pool is a unique subsurface remnant of the prehistoric chain of lakes which in Pleistocene times formed the Death Valley Lake System, and is unusual among caverns in that it is a solution area in distinctly striated limestone, while also owing its formation in part to fault action; and

"WHEREAS the geologic evidence that this subterranean pool is an integral part of the hydrographic history of the Death Valley region is further confirmed by the presence in this pool of a peculiar race of desert fish, and zoologists have demonstrated that this race of fish, which is found nowhere else in the world, evolved only after the gradual drying up of the Death Valley Lake System isolated this fish population from the original ancestral stock that in Pleistocene times was common to the entire region; and

"WHEREAS the said pool is of such outstanding scientific importance that it should be given special protection, and such protection can be best afforded by making the said forty-acre tract containing the pool a part of the said monument . . .."

The Proclamation provides that Devil's Hole should be supervised, managed, and directed by the National Park Service, Department of the Interior. Devil's Hole is fenced off, and only limited access is allowed byhe Park Service.

The Cappaert petitioners own a 12,000-acre ranch near Devil's Hole, 4,000 acres of which are used for growing Bermuda grass, alfalfa, wheat, and barley; 1,700 to 1,800 head of cattle are grazed. The ranch represents an investment of more than $7 million; it employs more than 80 people with an annual payroll of more than $340,000.

In 1968 the Cappaerts began pumping groundwater on their ranch on land 21/2 miles from Devil's Hole; they were the first to appropriate groundwater. The groundwater comes from an underground basin or aquifer which is also the source of the water in Devil's Hole. After the Cappaerts began pumping from the wells near Devil's Hole, which they do from March to October, the summer water level of the pool in Devil's Hole began to decrease. Since 1962 the level of water in Devil's Hole has been measured with reference to a copper washer installed on one of the walls of the hole by the United States Geological Survey. Until 1968, the water level, with seasonable variations, had been stable at 1.2 feet below the copper marker. In 1969 the water level in Devil's Hole was 2.3 feet below the copper washer; in 1970, 3.17 feet; in 1971, 3.48 feet; and, in 1972, 3.93 feet.

When the water is at the lowest levels, a large portion of a rock shelf in Devil's Hole is above water. However, when the water level is at 3.0 feet below the marker or higher, most of the rock shelf is below water, enabling algae to grow on it. This in turn enables the desert fish (Cyprinodon diabolis, commonly known as Devil's Hole pupfish), referred to in President Truman's Proclamation, to spawn in the spring. As the rock shelf becomes exposed, the spawning area is decreased, reducing the ability of the fish to spawn in sufficient quantities to prevent extinction.

In April 1970 the Cappaerts, pursuant to Nevada law, Nev.Rev.Stat. § 533.325 (1973), applied to the State Engineer, Roland D. Westergard, for permits to change the use of water from several of their wells. Although the United States was not a party to that proceeding and was never served, employees of the National Park Service learned of the Cappaerts' application through a public notice published pursuant to Nevada law. § 533.360. An official of the National Park Service filed a protest as did a private firm. Nevada law permits interested persons to protest an application for a permit; the protest may be considered by the State Engineer at a hearing. § 533.365. A hearing was conducted on December 16, 1970, and a field solicitor of the Department of the Interior appeared on behalf of the National Park Service. He presented documentary and testimonial evidence, informing the State Engineer that because of the declining water level of Devil's Hole the United States had commissioned a study to determine whether the wells on the Cappaerts' land were hydrologically connected to Devil's Hole and, if so, which of those wells could be pumped safely and which should be limited to prevent lowering of the water level in Devil's Hole. The Park Service field solicitor requested either that the Cappaerts' application be denied or that decision on the application be postponed until the studies were completed.

The State Engineer declined to postpone decision. At the conclusion of the hearing he stated that there was no recorded federal water right with respect to Devil's Hole, that the testimony indicated that the Cappaerts' pumping would not unreasonably lower the water table or adversely affect existing water rights, and that the permit would be granted since further economic development of the Cappaerts' land would be in the public interest. In his oral ruling the State Engineer stated in part that "the protest to the applications that are the subject of this hearing are overruled and the applications will be issued subject to existing rights." The Natnal Park Service did not appeal. See Nev.Rev.Stat. § 533.450 (1973).

In August 1971 the United States, invoking 28 U.S.C. § 1345,2 sought an injunction in the United States District Court for the District of Nevada to limit, except for domestic purposes, the Cappaerts' pumping from six specific wells and from specific locations near Devil's Hole. The complaint alleged that the United States, in establishing Devil's Hole as part of Death Valley National Monument, reserved the unappropriated waters appurtenant to the land to the extent necessary for the requirements and purposes of the reservation. The complaint further alleged that the Cappaerts had no perfected water rights as of the date of the reservation. The United States asserted that pumping from certain of the Cappaerts' wells had lowered the water level in Devil's Hole, that the lower water level was threatening the survival of a unique species of fish, and that irreparable harm would follow if the pumping were not enjoined. On June 2, 1972, the United States filed an amended complaint, adding two other specified wells to the list of those to be enjoined.

The Cappaerts answered, admitting that their wells draw water from the same underlying sources supplying Devil's Hole, but denying that the reservation of Devil's Hole reserved any water rights for the UniteStates. The Cappaerts alleged that the United States was estopped from enjoining use of water under land which it had exchanged with the Cappaerts. The State of Nevada intervened on behalf of the State Engineer as a party defendant but raised no affirmative defenses.

On June 5, 1973, the District Court, by Chief Judge Roger D. Foley, entered a preliminary injunction limiting pumping from designated wells so as to return the level of Devil's Hole to not more than 3.0 feet below the marker. Detailed findings of fact were made and the District Judge then appointed a Special Master to establish specific pumping limits for the wells and to monitor the level of the water at Devil's Hole. The District Court found that the water from certain of the wells was hydrologically connected to Devil's Hole, that the Cappaerts were pumping heavily from those wells, and that that pumping had lowered the water level in Devil's Hole. The court also found that the pumping could be regulated to stabilize the water level at Devil's Hole and that neither establishing an artificial shelf nor transplanting the fish was a feasible alternative that would preserve the species. The District Court further found that if the injunction did not issue "there is grave danger that the Devil's Hole pupfish may be destroyed, resulting in irreparable injury to the United States." 375 F.Supp., 456, 460 (1974).

The District Court then held that in establishing Devil's Hole as a national monument, the President reserved appurtenant, unappropriated waters necessary to the purpose of the reservation; the purpose included preservation of the pool and the pupfish in it. The District Court also held that the federal water rights antedated those of the Cappaerts, that the United States was not estopped, and that the public interest required granting the injunction. On April 9, 1974, the District Court entered its findings of fact and conclusions of law substantially unchanged in a final decree permanently enjoining pumping that lowers the level of the water below the 3.0-foot level. 375 F.Supp. 456 (1974).

The Court of Appeals for the Ninth Circuit affirmed, 508 F.2d 313 (1974),3 in a thorough opinion by Senior District Judge Gus J. Solomon, sitting by designation, holding that the implied-reservation-of-water doctrine applied to groundwater as well as to surface water. The Court of Appeals held that "(t) he fundamental purpose of the reservation of the Devil's Hole pool was to assure that the pool would not suffer changes from its condition at the time the Proclamation was issued in 1952 . . . ." Id., at 318. The Court of Appeals further held that neither the Cappaerts nor their successors in interest had any water rights in 1952, nor was the United States estopped from asserting its water rights by exchanging land with the Cappaerts. In answer to contentions raised by the intervenor Nevada, the Court of Appeals held that "the United States is not bound by state water laws when it reserves land from the public domain," Id., at 320, and does not need to take steps to perfect its rights with the State; that the District Court had concurrent jurisdiction with the state courts to resolve this claim; and, that the state administrative procedures granting the Cappaerts' permit did not bar resolution of the United States' suit in Federal District Court.

We granted certiorari to consider the scope of the implied-reservation-of- water-rights doctrine. 422 U.S. 1041, 95 S.Ct. 2654, 45 L.Ed.2d 692 (1975). We affirm.

* Reserved-Water-Rights Doctrine

This Court has long held that when the Federal Government withdraws its land from the public domain and reserves it for a federal purpose, the Government, by implication, reserves appurtenant water then unappropriated to the extent needed to accomplish the purpose of the reservation. In so doing the United States acquires a reserved right in unappropriated water which vests on the date of the reservation and is superior to the rights of future appropriators. Reservation of water rights is empowered by the Commerce Clause, Art. I, § 8, which permits federal regulation of navigable streams, and the Property Clause, Art. IV, § 3, which permits federal regulation of federal lands. The doctrine applies to Indian reservations and other federal enclaves, encompassing water rights in navigable and nonnavigable streams. Colorado River Water Cons. Dist. v. United States, 424 U.S. 800, 805, 96 S.Ct. 1236, 1240, 47 L.Ed.2d 483 (1976); United States v. District Court for Eagle County, 401 U.S. 520, 522-523, 91 S.Ct. 998, 1000-1001, 28 L.Ed.2d 278, 280-281 (1971); Arizona v. California, 373 U.S. 546, 601, 83 S.Ct. 1468, 1498, 10 L.Ed.2d 542, 578 (1963); FPC v. Oregon, 349 U.S. 435, 75 S.Ct. 832, 99 L.Ed. 1215 (1955); United States v. Powers, 305 U.S. 527, 59 S.Ct. 344, 83 L.Ed. 330 (1939); Winters v. United States, 207 U.S. 564, 28 S.Ct. 207, 52 L.Ed. 340 (1908).

Nevada argues that the cases establishing the doctrine of federally reserved water rights articulate an equitable doctrine calling for a balancing of competing interests. However, an examination of those cases shows they do not analyze the doctrine in terms of a balancing test. For example, in Winters v. United States, supra, the Court did not mention the use made of the water by the upstream landowners in sustaining an injunction barring their diversions of the water. The "Statement of the Case" in Winters notes that the upstream users were homesteaders who had invested heavily in dams to divert the water to irrigate their land, not an unimportant interest. The Court held that when the Federal Government reserves land, by implication it reserves water rights sufficient to accomplish the purposes of the reservation.4

In determining whether there is a federally reserved water right implicit in a federal reservation of public land, the issue is whether the Government intended to reserve unappropriated and thus available water. Intent is inferred if the previously unappropriated waters are necessary to accomplish the purposes for which the reservation was created. See, E. g., Arizona v. California, supra, 373 U.S., at 599-601, 83 S.Ct., at 1497-1498, 10 L.Ed.2d, at 577-578; Winters v. United States, supra, 207 U.S., at 576, 28 S.Ct., at 211, 52 L.Ed., at 346. Both the District Court and the Court of Appeals held that the 1952 Proclamation expressed an intention to reserve unappropriated water, and we agree.5 The Proclation discussed the pool in Devil's Hole in four of the five preambles and recited that the "pool . . . should be given special protection." Since a pool is a body of water, the protection contemplated is meaningful only if the water remains; the water right reserved by the 1952 Proclamation was thus explicit, not implied.6

Also explicit in the 1952 Proclamation is the authority of the Director of the Park Service to manage the lands of Devil's Hole Monument "as provided in the act of Congress entitled 'An Act to establish a National Park Service, and for other purposes,' approved August 25, 1916 (39 Stat. 535; 16 U.S.C. §§ 1-3) . . . ." The National Park Service Act provides that the "fundamental purpose of the said parks, monuments, and reservations" is "to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of thsame in such manner and by such means as will leave them unimpaired for the enjoyment of future generations." 39 Stat. 535, 16 U.S.C. § 1.

The implied-reservation-of-water-rights doctrine, however, reserves only that amount of water necessary to fulfill the purpose of the reservation, no more. Arizona v. California, supra, 373 U.S., at 600-601, 83 S.Ct., at 1497-1498, 10 L.Ed.2d, at 578-579. Here the purpose of reserving Devil's Hole Monument is preservation of the pool. Devil's Hole was reserved "for the preservation of the unusual features of scenic, scientific, and educational interest." The Proclamation notes that the pool contains "a peculiar race of desert fish . . . which is found nowhere else in the world" and that the "pool is of . . . outstanding scientific importance . . . ." The pool need only be preserved, consistent with the intention expressed in the Proclamation, to the extent necessary to preserve its scientific interest. The fish are one of the features of scientific interest. The preamble noting the scientific interest of the pool follows the preamble describing the fish as unique; the Proclamation must be read in its entirety. Thus, as the District Court has correctly determined, the level of the pool may be permitted to drop to the extent that the drop does not impair the scientific value of the pool as the natural habitat of the species sought to be preserved. The District Court thus tailored its injunction, very appropriately, to minimal need, curtailing pumping only to the extent necessary to preserve an adequate water level at Devil's Hole, thus implementing the stated objectives of the Proclamation.

Petitioners in both cases argue that even if the intent of the 1952 Proclamation were to maintain the pool, the American Antiquities Preservation Act did not give the President authority to reserve a pool. Under that Act, according to the Cappaert petitioners, the President may reserve federal lands only to protect archeologic sites. However, the language of the Act which authorizes the President to proclaim as national monuments "historic landmarks, historic and prehistoric stctures, and other objects of historic or scientific interest that are situated upon the lands owned or controlled by the Government" is not so limited. The pool in Devil's Hole and its rare inhabitants are "objects of historic or scientific interest." See generally Cameron v. United States, 252 U.S. 450, 455-456, 40 S.Ct. 410, 411, 64 L.Ed. 659, 661 (1920).

No cases of this Court have applied the doctrine of implied reservation of water rights to groundwater. Nevada argues that the implied-reservation doctrine is limited to surface water. Here, however, the water in the pool is surface water. The federal water rights were being depleted because, as the evidence showed, the "(g)roundwater and surface water are physically interrelated as integral parts of the hydrologic cycle." C. Corker, Groundwater Law, Management and Administration, National Water Commission Legal Study No. 6, p. xxiv (1971). Here the Cappaerts are causing the water level in Devil's Hole to drop by their heavy pumping. See Corker, Supra ; see also Water Policies for the Future Final Report to the President and to the Congress of the United States by the National Water Commission 233 (1973). It appears that Nevada itself may recognize the potential interrelationship between surface and groundwater since Nevada applies the law of prior appropriation to both. Nev.Rev.Stat. §§ 533.010 Et seq., 534.020, 534.080, 534.090 (1973). See generally F. Trelease, Water Law Resource Use and Environmental Protection 457-552 (2d ed. 1974); C. Meyers & A. Tarlock, Water Resource Management 553-634 (1971). Thus, since the implied-reservation-of-water-rights doctrine is based on the necessity of water for the purpose of the federal reservation, we hold that the United States can protect its water from subsequent diversion, whether the diversion is of surface or groundwater.7

Petitioners in both cases argue that the Federal Government must perfect its implied water rights according to state law. They contend that the Desert Land Act of 1877, 19 Stat. 377, 43 U.S.C. § 321, and its predecessors8 severed nonnavigable water from public land, subjecting it to state law. That Act, however, provides that patentees of public land acquire only title to land through the patent and must acquire water rights in nonnavigable water in accordance with state law. California Oregon Power Co. v. Beaver Portland Cement Co., 295 U.S. 142, 162, 55 S.Ct. 725, 730, 79 L.Ed. 1356, 1363 (1935); see Morreale, Federal-State Conflicts Over Western Waters A Decade of Attempted "Clarifying Legislation," 20 Rutgers L.Rev. 423, 432 (1966).9 This Court held in FPC v. Oregon, 349 U.S. 435, 448, 75 S.Ct. 832, 840, 99 L.Ed. 1215, 1226 (1955), that the Desert Land Act does not apply to water rights on federally reserved land.10

The Cappaert petitioners argue that FPC v. Oregon, supra, must be overruled since, Inter alia, the Court was unaware at the time that case was decided that there was no longer any public land available for homesteading. However, whether or not there was public land available for homesteading in 1955 is irrelevant to the meaning of the 1877 Act. The Desert Land Act still provides that the water rights of those who received their land from federal patents are to be governed by state law. That there may be no more federal land available for homesteading does not mean the Desert Land Act now applies to all federal land. Since the Act is inapplicable, determination of reserved water rights is not governed by state law but derives from the federal purpose of the reservation; the fact that the water rights here reserved apply to nonnavigable rather than navigable waters is thus irrelevant.

Since FPC v. Oregon, supra, was decided, several bills have been introduced in Congress to subject at least some federal water uses to state appropriation doctrines, but none has been enacted into law. The most recent bill, S. 28, 92d Cong., 1st Sess., was introduced on January 25, 1971, and reintroduced under the same number in the 93d Cong., 1st Sess., on January 4, 1973. See Morreale, Supra.

Federal water rights are not dependent upon state law or state procedures and they need not be adjudicated only in state courts; federal courts have jurisdiction under 28 U.S.C. § 1345 to adjudicate the water rights claims of the United States.11 Colorado River Water Cons. Dist. v. United States, 424 U.S., at 807-809, 96 S.Ct., at 1240-1242, 47 L.Ed.2d, at 491-493. The McCarran Amendment, 66 Stat. 560, 43 U.S.C. § 666, did not repeal § 1345 jurisdiction as applied to water rights. 424 U.S., at 808-809, 96 S.Ct., at 1242, 47 L.Ed.2d at 493. Nor, as Nevada suggests, is the McCarran Amendment a substantive statute, requiring the United States to "perfect its water rights in the state forum like all other land owners." Brief for Nevada 37. The McCarran Amendment waives United States' sovereign immunity should the United States be joined as a party in state-court general water rights' adjudication. Colorado River Water Cons. Dist. v. United States, supra, at 808, 96 S.Ct., at 1241-1242, 47 L.Ed.2d, at p. 492 and the policy evinced by the Amendment may, in the appropriate case, require the United States to adjudicate its water rights in state forums. Id., at 817-820, 96 S.Ct., at 1246-1248, 47 L.Ed.2d, at 498-499.

Finally, Nevada, as intervenor in the Cappaerts' suit, argued in the Court of Appeals that the United States was barred by res judicata or collateral estoppel from litigating its water-rights claim in federal court. Nevada bases this conclusion on the fact that the National Park Service filed a protest to the Cappaerts' pumping permit application in the state administrative proceeding. Since we reject that contention, we need not consider whether the issue was timely and properly raised. We note only that the United States was not made a party to the state administrative proceeding;12 nor was the United States in privity with the Cappaerts. See Blonder-Tongue Labs, Inc. v. University of Illinois Foundation, 402 U.S. 313, 320-326, 91 S.Ct. 1434, 1438-1441, 28 L.Ed.2d 788, 794-798 (1971). When the United States appeared to protest in the state proceeding it did not assert any federal water-rights-claims, nor did it seek to adjudicate any claims until the hydrological studies as to the effects of the Cappaerts' pumping had been completed.13 The fact that the United States did not attempt to adjudicate its water rights in the state proceeding is not significant since the United States was not a party. The State Water Engineer's decree explicitly stated that it was "subject to existing rights"; thus, the issue raisedn the District Court was not decided in the proceedings before the State Engineer. See Blonder-Tongue Labs, Inc. v. University of Illinois Foundation, supra, 402 U.S., at 323, 91 S.Ct., at 1439, 28 L.Ed.2d, at 796. Cf. United States v. Utah Const. & Min. Co., 384 U.S. 394, 422, 86 S.Ct. 1545, 1560, 16 L.Ed.2d 642, 660 (1966).

We hold, therefore, that as of 1952 when the United States reserved Devil's Hole, it acquired by reservation water rights in unappropriated appurtenant water sufficient to maintain the level of the pool to preserve its scientific value and thereby implement Proclamation No. 2961. Accordingly, the judgment of the Court of Appeals is

Affirmed.