Opinion of the Court Between May and July 1983, the feature was observed above water several times, although its elevation in relation to mean high water was not known. Based on two helicopter observations of the feature and estimates of sea level in relation to mean high water, the Master concluded that Dinkum Sands could have been above high water by a matter of inches in September 1983. The Master found that the feature was "consistently" below mean high water in 1981 and below mean high water by September-the end of the open water season-in both 1981 and 1982. Id., at 309. Relying largely on the 1981-1983 data, the Master concluded that Dinkum Sands is not an island. Alaska makes no mention of the 1981 joint monitoring project. The Master discussed the State's methodological objections to the results at length, see id., at 255-269, and we see no reason to revisit the Master's conclusion that those objections are unpersuasive. Alaska does not explain why the Master should have relied on a single August 1949 measurement of Dinkum Sands' elevation in relation to mean high water rather than on the exhaustive survey expressly designed to determine Dinkum Sands' status under Article 10(1) of the Convention. In contending that Dinkum Sands has been above mean high water except on a "handful of occasions," Alaska recognizes that Dinkum Sands slumps in elevation during the open water season between late July and September. Alaska Exceptions Brief 54. Alaska suggests that natural processes build up Dinkum Sands “just . . . prior to the autumn freeze-up," and that the feature then remains above mean high water for 9 to 10 months of the year. See ibid. There is no basis in the record, however, for concluding that Dinkum Sands is above mean high water during the winter months. During the winter, the area is completely covered by pack ice. The sole measurement of the feature's elevation during the winter was that taken in March 1981, and it was then below mean high water. Report 286. But even if the record demonstrated that the Opinion of the Court feature remained above mean high water until "ice collapse" caused it to slump, that would not compel a ruling in Alaska's favor. Although Article 10(1)'s drafting history may suggest that a feature submerged at abnormally high tides does not lose its insular status, it does not support the broader conclusion that a feature with a seasonal loss in elevation, bringing it below mean high water, qualifies as an island. See supra, at 27. In sum, we find no error in the Master's conclusion that Dinkum Sands is frequently below mean high water and therefore does not meet the standard for an island. C Alaska finally urges a compromise resolution, under which Dinkum Sands would be deemed an island when above mean high water. Alaska attempts to find support for its position in this Court's recognition in prior cases of the concept of an "ambulatory coast line." Alaska Exceptions Brief 55. In adopting the 1958 Convention to aid interpretation of the Submerged Lands Act, we recognized that the Convention treats a nation's coastline as its modern, ambulatory coastline. See United States v. Louisiana, 394 U. S. 1, 5 (1969) (Texas Boundary Case); Louisiana Boundary Case, 394 U. S., at 32–34. Shifts in a low-water line along the shore, we acknowledged, could lead to a shift in the baseline for measuring a maritime zone for international purposes. In turn, the State's entitlement to submerged lands beneath the territorial sea would change. An island may very well have its own ambulatory coastline. What Alaska seeks here, however, is not an entitlement to submerged lands seaward of a gradually accreting or eroding shore. Rather, Alaska's ownership of submerged lands around Dinkum Sands would appear and disappear periodically, depending upon whether the feature was above or below mean high water. Not only does Article 10(1) of the Convention not support such a reading, but Alaska's position Opinion of the Court makes a sensible application of other provisions of the Convention impossible. The Convention separately categorizes features that are below mean high water, but above water at low tide. See Art. 11. In addition, under Articles 10(2) and 3, an island's belt of territorial sea is measured from the line of low water. As Dinkum Sands' elevation shifts and the feature slumps toward the mean high-water datum, below the mean high-water datum, and possibly below the low-water datum, the baseline for measuring the surrounding maritime zone would shift and then disappear. Quite apart from the fact that Alaska's proposal would lead to costly and time-consuming monitoring efforts, we agree with the Master that Alaska has identified no precedent for treating as an island a feature that oscillates above and below mean high water. IV Alaska's third exception concerns the ownership of submerged lands within the National Petroleum Reserve-Alaska (Reserve), a 23-million acre federal reservation in the northwestern part of the State. The Reserve's seaward boundary runs along the Arctic Ocean from Icy Cape at the west to the mouth of the Colville River at the east. When this litigation began, Alaska and the United States disputed the location of the Reserve's boundary, focusing in particular on whether the boundary followed the sinuosities of the coast or instead cut across certain inlets, bays, and river estuaries. Alaska initially conceded federal ownership of submerged lands within that boundary. In light of this Court's decision in Montana v. United States, 450 U. S. 544 (1981), and with the consent of the United States, the Special Master granted Alaska relief from its concession, and Alaska claimed ownership of submerged lands beneath certain coastal features within the Reserve's boundaries. Order of Special Master in United States v. Alaska, O. T. 1983, No. 84 Orig. (Jan. 4, 1984). A separate proceeding concerning ownership of submerged lands beneath inland navigable waters is pending in Opinion of the Court Federal District Court, Alaska v. United States, Nos. A83343, A84-435, A86-191 (D. Alaska), and has been stayed until resolution of the present case, see Report 347, n. 4. The parties no longer dispute the location of the Reserve's boundary. Accordingly, we consider only the Master's recommendation concerning the ownership of submerged lands beneath certain coastal features within that boundary. The Master concluded that the United States retained ownership of the submerged lands in question at Alaska's statehood. That conclusion rested principally on three premises: first, that the United States can prevent lands beneath navigable waters from passing to a State upon admission to the Union by reserving those lands in federal ownership (as opposed to conveying them to a third party); second, that Congress had authorized the President to reserve submerged lands with a 1910 statute known as the Pickett Act; and third, that the 1923 Executive Order creating the Reserve reflected a clear intent to reserve all submerged lands within the boundaries of the Reserve and to defeat the State's title to the submerged lands in question. Alaska excepts to the Master's conclusion on several grounds, arguing that the Government did not show a sufficiently clear intent to reserve submerged lands or to defeat state title and that the 1923 Executive Order was promulgated without proper authority. We discuss some background principles and then consider these arguments in turn. A The Property Clause, Art. IV, § 3, cl. 2, provides that "Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States." In Shively v. Bowlby, 152 U. S. 1, 48 (1894), the Court concluded that this power extended to granting submerged lands to private parties, and thereby defeating a future State's equal footing title, "to carry out . . . public purposes appropriate to the objects for which the United States hold the Territory." We Opinion of the Court agree with the Special Master that Congress can also reserve submerged lands under federal control for an appropriate public purpose, and thus resolve a question left open in Utah Div. of State Lands, 482 U. S., at 201, in the United States' favor. As drawn by the Master, the boundary of the Reserve encompasses both those lands that would ordinarily pass to Alaska under the equal footing doctrine-that is, tidelands and submerged lands beneath inland navigable waters-and those lands that would pass to Alaska only by virtue of the Submerged Lands Act—that is, lands beneath the 3-mile territorial sea. As a result, the parties dispute the principles governing ownership of the submerged lands. Under our equal footing cases, "[a] court deciding a question of title to the bed of navigable water must . . . begin with a strong presumption" against defeat of a State's title. Montana, supra, at 552; see Utah Div. of State Lands, supra, at 197-198. We will not infer an intent to defeat a future State's title to inland submerged lands "unless the intention was definitely declared or otherwise made very plain." United States v. Holt State Bank, 270 U. S. 49, 55 (1926). The United States argues that the presumption against defeat of state title does not apply to lands passing solely under the Submerged Lands Act-that is, lands beneath the territorial sea-over which the United States has paramount authority: Any grant of such lands is to be "construed strictly in favor of the United States.'" United States Opposition Brief 53 (quoting California ex rel. State Lands Comm'n, 457 U. S., at 287). The Master agreed with the Government's approach, concluding that the United States can demonstrate that it retained title to submerged lands beneath the territorial sea under a "less demanding standard" than our equal footing cases require. Report 394. Nevertheless, the Master analyzed the withdrawal under the "stricter" standards of Utah Div. of State Lands and Montana, reasoning that the less demanding test for lands be |