Mb. Justice Brennan
delivered the opinion of the Court.
This proceeding is a sequel to last Term’s United States v. Louisiana, 389 U. S. 155 (1967), in which we held that the three-league (nine-mile) belt of submerged lands beneath the Gulf of Mexico granted to Texas by the Submerged Lands Act of 1953 was not to be measured from the edge of artificial jetties built in the Gulf by Texas since 1845 but from Texas’ coastline as it existed in 1845 when Texas was admitted to the Union. The cartographic work required to define the 1845 coastline and the gulfward boundary three leagues distant has been completed, and the United States and Texas have agreed upon their locations. However, the 1845 coastline has been substantially modified by extensive erosion and some accretion in the intervening period of more than a century. This modification has occasioned a dispute between the United States and Texas as to whether the Act’s express limitation in § 2 (b), that in no event shall the boundaries of the grant of submerged lands “be interpreted as extending from the coast line ... more than three marine leagues into the Gulf of Mexico,” is to be read as measuring from the 1845 coastline, as Texas contends, or from the coastline as it exists currently or at any time in the future, as the United States contends. If the limitation is read as measuring from the modern, ambulatory coastline, Texas claims that it would be denied substantial submerged acreage as a result of post-1845 erosion. We ordered oral argument. 393 U. S. 811 (1968). We agree with the United States that the term “coast line” means the modern, ambulatory coastline.
The term “coast line” also appears in § 4 of the Submerged Lands Act. Section 4 approves a seaward boundary three miles distant from the “coast line” of each coastal State, except that if a State can show that its boundary as it existed at the time of entry into the Union or as approved by Congress extended into the Gulf of Mexico more than three miles from the coastline, that State is entitled to claim the submerged lands within such boundary, subject however to the express limitation of § 2 (b). See §§ 2 and 4, 67 Stat. 29, 31, 43 U. S. C. §§ 1301, 1312; United States v. Louisiana, 363 U. S. 1 (1960).
The argument of the United States that “coast line” means the modern ambulatory coastline is based on our decision in United States v. California, 381 U. S. 139 (1965). The issue there was whether particular bodies of water on the California coast were “inland waters” within the meaning of § 2 (c) which provides that “[t]he term 'coast line’ means the line . . . marking the seaward limit of inland waters.” We held that the legislative history showed that Congress intended that the courts should define the term “inland waters.” In discharging that assignment we concluded that the Convention on the Territorial Sea and the Contiguous Zone provided “the best and most workable definitions available.” Accordingly, we adopted those definitions for purposes of the Submerged Lands Act. 381 U. S., at 165. The Convention defines “coast line” as the modern, ambulatory coastline; the decree entered several months later in accordance with our opinion in California expressly provides that “[t]he coast line is to be taken as heretofore or hereafter modified by natural or artificial means . . . .” 382 U. S. 448, 449 (1966).
We said further in California that “[t]his [adoption of the Convention’s definitions] establishes a single coastline for . . . the administration of the Submerged Lands Act . . . .” 381 U. S., at 165. Our conclusion in this case that “coast line” means the modern, ambulatory coastline therefore necessarily follows from our decision in California. See United States v. Louisiana, supra, 389 U. S., at 162, n. 2 (Stewart, J., concurring in result). There is no basis for a finding that “coast line” has a different meaning for the purpose of determining the baseline for measurement of the three-league maximum limitation. Nothing on the face of the Act or in its legislative history supports a different meaning. Rather it seems evident that Congress meant that the same “coast line” should be the baseline of both the three-mile grant and the three-league limitation. Texas suggests no ground for a distinction, but argues that measurement from the modern, ambulatory coastline would produce an inequitable result and work havoc with orderly mineral development. It is true that last Term’s decision that the three-league belt should be measured from the 1845 coastline and not from the edge of subsequently constructed artificial jetties deprived Texas of the benefit of post-1845 accretion. It is also true that the use of the modern, ambulatory coastline as the baseline from which the limitation is measured will penalize Texas for post-1845 erosion and may present practical difficulties for mineral lessees. But any alleged inequitable results, as well as any alleged detriment to orderly mineral development, derive from a consistent reading of the scheme Congress fashioned; thus Texas must look to Congress for relief.
Since the parties have agreed that the decree proposed by the United States should be entered if its view on the disputed point is sustained, we direct the entry of the supplemental decree proposed by the United States.
It is so ordered.
The Chief Justice and Mr. Justice Marshall took no part in the consideration or decision of this case.
[For supplemental decree entered in this case, see post, p. 836.]
67 Stat. 29, 43 U. S. C. §§ 1301-1315. In United States v. Louisiana, 363 U. S. 1, 84 (1960), we held that the Act entitled Texas, as against the United States, to the submerged lands underlying the Gulf of Mexico to a distance of three marine leagues from Texas’ “coast line.” We expressly reserved the question of what is the “coast line” from which to measure this three-league grant. 363 U. S., at 79. See also 389 U. S., at 156-157 and n. 1.
A Stipulation filed with the Court identifies Texas’ 1845/1849 coastline and also its gulfward boundary three leagues distant. An Act of November 24, 1849, Laws, 3d Tex. Leg., c. 2, p. 4, adopted with the consent of Congress, Act of July 5, 1848, 9 Stat. 245, extended Texas’ boundary opposite Sabine Pass. The United States has accepted Texas’ three-league boundary opposite the western half of Sabine Pass, not as a boundary as it existed when the State came into the Union in 1845, but as one approved by Congress before passage of the Submerged Lands Act, and as such equally entitled to recognition under §2(b). The line identified in the Stipulation as the line to be recognized as Texas’ historic offshore boundary includes the 1849 extension, but the United States reserves the effectiveness of that extension as against other claims, for example, any that might be asserted by Louisiana. See Memorandum of United States 16-18.
Section 2, 43 U. S. C. §1301, so far as relevant here, is as follows:
“(a) The term lands beneath navigable waters’ means—
“(2) all lands permanently or periodically covered by tidal waters up to but not above the line of mean high tide and seaward to a line three geographical miles distant from the coast line of each such State and to the boundary line of each such State where in any case such boundary as it existed at the time such State became a member of the Union, or as heretofore approved by Congress, extends seaward (or into the Gulf of Mexico) beyond three geographical miles,
“(b) The term ‘boundaries’ includes the seaward boundaries of a State or its boundaries in the Gulf of Mexico or any of the Great Lakes as they existed at the time such State became a member of the Union, or as heretofore approved by the Congress, or as extended or confirmed pursuant to section 4 hereof but in no event shall the term ‘boundaries’ or the term lands beneath navigable waters’ be interpreted as extending from the coast line more than three geographical miles into the Atlantic Ocean or the Pacific Ocean, or more than three marine leagues into the Gulf of Mexico;
“(c) The term ‘coast line’ means the line of ordinary low water along that portion of the coast which is in direct contact with the open sea and the line marking the seaward limit of inland waters.”
It was represented on oral argument that between 17,000 and 35,000 acres would be lost to Texas as a result of such erosion.
[1964] 15 U. S. T. (pt. 2) 1607, T. I. A. S. No. 5639.
Our decision in California also forecloses any argument that the term “coast line” means the coastline as it existed at the date of passage of the Submerged Lands Act.
Although the three-mile minimum grant measured from the modern coastline has no present application in the case of Texas, the decree includes provisions to cover the situation which would exist if accretion or artificial construction should at some future time extend the coastline more than six miles beyond the 1845-1849 position.