that such a line could be drawn. In accordance with the views of Grotius and Vattel, nations were agreed that it should pass through the middle of the stream. This method of division proved, however, to be unsatisfactory in the case of navigable rivers; for, in disregarding the course of the principal channel, it was likewise heedless of the equities of the State which happened to be the more remote therefrom. Nor did it adapt itself to gradual changes which such channel might undergo.2 As a result, at the beginning of the nineteenth century, riparian States began to conclude treaties, which proposed a different method of division, and which has since become the accepted mode of indicating the frontier. There has thus developed a practice manifesting general adherence to a particular doctrine.3

§ 138. Thalweg.

(ii)

It has long been agreed that when a navigable river forms the boundary between two States, the dividing line follows the thalweg of the stream. The thalweg, as the derivation of the word in

1 De Jure Belli et Pacis, Book II, Chap. 3, Secs. 7 and 8; Chitty's Vattel (1859), Chap. 22, Sec. 266, p. 120.

2 E. Engelhardt, Du Régime Conventionnel des Fleuves Internationaux, Paris, 1879, 73; Pierre Orban, Etude de Droit Fluvial International, Paris, 1896, 342

346.

3 Art. VI of Treaty of Luneville, Feb. 9, 1801, De Clercq, Traités, I, 426, following the views expressed by the French plenipotentiaries at the Congress of Rastadt in March and April, 1798.

4 Numerous treaties since the beginning of the nineteenth century make express provision that the frontier along navigable rivers shall follow the thalweg. See, for example, Art. V of the definitive treaty between France and the Allies of May 30, 1814, Brit. and For. State Pap., I, Pt. I, 156; also collection of treaties containing similar provisions, in the argument of the United States in the Chamizal Arbitration (Washington, 1911), 10-21. Among recent conventions to the same effect may be noted that between the Argentine Republic and Brazil of Oct. 6, 1898, Brit. and For. State Pap., XC, 85; also that between Great Britain and France of June 14, 1898, for the delimitation of possessions west of the Niger, Brit. and For. State Pap., XCI, 38, 45. Cf. also Art. I, Treaty of Constantinople, between Turkey and Bulgaria, of Sept. 16/29, 1913, Brit. and For. State Pap., CVII, 706, 709.

The treaties of the United States concerning river boundaries lack uniformity of expression. Art. II of the definitive treaty of peace with Great Britain of Sept. 3, 1783, provided that the frontier should follow the "middle" of boundary rivers as well as of water communications between the Lakes. Malloy's Treaties, I, 587. Art. I of the Webster-Ashburton Treaty of Aug. 9, 1842, provided that the frontier along the river St. John should follow the "middle of the main channel." Id., I, 651. The treaty of April 11, 1908, concerning the Canadian international boundary, provided in Art. II respecting the St. Croix River, that the line should "follow the center of the main channel or thalweg as naturally existing, except where such course would change or disturb or conflict with the national character of islands as already established by mutual recognition and acquiescence." Id., I, 818. This is

THALWEG

[§ 138 dicates, is the downway, or the course followed by vessels of largest tonnage in descending the river.1 That course frequently, if not commonly, corresponds with the deepest channel. It may, however, for special reasons take a different path. Wheresoever that may be, such a course necessarily indicates the principal artery of commerce, and for that reason is decisive of the thalweg.2

the first boundary convention of the United States in which the term thalweg was employed.

Art. II of the treaty with Spain of Oct. 27, 1795, provided that the boundary along St. Mary's River should follow the "middle thereof"; while Art. IV declared that the "western boundary of the United States which separates them from the Spanish colony of Louisiana is the middle of the channel or bed of the river Mississippi." Id., II, 1641, 1642. Art. III of the treaty with Spain of Feb. 22, 1819, provided that the boundary should follow the "course" of the Red River between specified points, all islands therein being assigned to the United States. Id., II, 1652-1653.

Art. II of the treaty with Mexico of Jan. 12, 1828, declared that between specified points the boundary should follow the "course" of the Rio Roxo or Red River. Id., I, 1083. According to Art. V of the Treaty of GuadalupeHidalgo of Feb. 2, 1848, the boundary was to proceed up the "middle" of the Rio Grande, "following the deepest channel where it has more than one"; also down the "middle" of a specified branch of the river Gila. Id., I, 1109. Art. I of the Gadsden Treaty with Mexico of Dec. 30, 1853, referred to the "middle" of the Rio Grande, and likewise to that of the Colorado. Id., I, 1122. In the preamble of the boundary convention with Mexico of Nov. 12, 1884, it was declared that according to the provisions of the two last-mentioned treaties the dividing line follows the "middle of the channel of the Rio Grande and Rio Colorado"; and it was, therefore, provided in Art. I that the dividing line should forever "follow the center of the normal channel of the rivers named, notwithstanding any alterations in the banks or in the course of those rivers, provided that such alterations be effected by natural causes through the slow and gradual erosion and deposit of alluvium, and not by the abandonment of an existing river bed and the opening of a new one." Id., I, 1159–1160. 1 Declares Westlake: "When a river forms the boundary between two States it is usual to say that the true line of demarcation is the thalweg, a German word meaning literally the 'downway'; that is, the course taken by boats going downstream, which again is that of the strongest current, the slack current being left for the convenience of ascending boats. Thal in the sense of valley enters into thalweg only indirectly. The immediate origin of the word lies in the use of berg and thal to express the upward and downward directions on a stream, like amont and aval in French.' Int. Law, 2 ed., I, 144, and note 1.

Declared the Supreme Court of the United States in the case of Louisiana v. Mississippi, 202 U. S. 1, 49: "The term 'thalweg' is commonly used by writers on international law in definition of water boundaries between States, meaning the middle or deepest or most navigable channel. And while often styled 'fairway' or 'midway' or 'main channel', the word itself has been taken over into various languages. Thus, in the treaty of Luneville, Feb. 9, 1801, we find 'le Thalweg de l'Adige', 'le Thalweg du Rhin', and it is similarly used in English treaties and decisions, and in the books of publicists in every tongue."

According to Art. III of the Draft of International Regulations for the Navigation of Rivers, adopted by the Institute of International Law in 1887, "The boundary of the States separated by the river is marked by the thalweg; that is, the median line of the channel." Annuaire, IX, 182, J. B. Scott, Resolutions, 78.

2 Minnesota v. Wisconsin, 252 U. S. 273, 282; Baker's 4th ed. of Halleck, 182, § 23.

The Supreme Court of the United States, recognizing the doctrine of thalweg, has declared that in the case of navigable boundary rivers the line follows the "middle of the main channel of the stream."

1

The boundary line is subject to the gradual and imperceptible changes of the thalweg due to accretion or erosion, and produced by natural causes.2 If from any cause the change is perceptible and sudden by a process known as avulsion, the boundary con

1 Iowa v. Illinois, 147 U. S. 1, 7-14; Handly's Lessee v. Anthony, 5 Wheat. 374; Buttenuth v. St. Louis Bridge Co., 123 Ill. 535; Keokuk & Hamilton Bridge Co. v. The People, 145 Ill. 596; Same v. Same, 167 Ill. 15; Keokuk & Hamilton Bridge Co. v. Illinois, 175 U. S. 626; Bellefontaine Improvement Co. v. Niedringhaus, 181 Ill. 426; Louisiana v. Mississippi, 202 U. S. 1; Iowa v. Illinois, 202 U. S. 59; Washington v. Oregon, 211 U. S. 127, 134; 214 U. S. 205, 215; Arkansas v. Tennessee, 246 U. S. 158; 247 U. S. 461; Arkansas v. Mississippi, 250 U. S. 39, 45. Compare opinion of Mr. Crittenden, AttorneyGeneral, 5 Ops. Attys.-Gen., 412.

The Supreme Court of the United States, in the case of Iowa v. Illinois, 147 U. S. 1, 7–14, declared that, according to international law and the usage of European States, the terms "middle of the stream" and the "mid-channel as applied to a navigable river, are synonymous and interchangeably used; and that the former was employed in the latter sense in the treaty of peace concluded by Great Britain, France and Spain at Paris in 1763. There is room for doubt whether the quotations made from Wheaton, Creassy, Twiss, Halleck, Woolsey and Phillimore sustain such a conclusion. It is believed that prior to the Treaty of Luneville of 1801, States commonly employed the term "middle of the stream" or "midstream" in boundary conventions for the reason that a line other than one drawn midway between the banks of a river was rarely contemplated. After that treaty, States having become familiar with the principle of thalweg, seem to have employed either that term, or some other clearly synonymous with it, whenever the new mode of demarcation was intended. The principal boundary treaties concluded since the beginning of the nineteenth century afford abundant evidence of the fact that States have generally taken great care to express their acceptance of the principle of thalweg, and have avoided the use of words the literal meaning of which might encourage the inference that the contracting parties sought to retain the old method of establishing a frontier.

Art. 30 of the treaty of peace with Germany of June 28, 1919, provided that "in the case of boundaries which are defined by a waterway, the terms 'course' and 'channel' used in the present treaty signify: in the case of nonnavigable rivers, the median line of the waterway or of its principal arm, and in the case of navigable rivers, the median line of the principal channel of navigation."

2 See opinion of Mr. Cushing, Attorney-General, 8 Ops. Attys.-Gen., 175; Nebraska v. Iowa, 143 U. S. 359; McBaine v. Johnson, 155 Missouri, 191; Bellefontaine Improvement Co. v. Niedringhaus, 181 Illinois, 426; Argument of the United States in the Chamizal Arbitration, p. 26. Also Art. I of the boundary convention between the United States and Mexico of Nov. 12, 1884, which is believed to express with exactness the correct rule of law in the requirement, that in order to subject the boundary to variations of the thalweg, the changes in the latter must be "effected by natural causes." Malloy's Treaties, I, 1159-1160.

In the case of Washington v. Oregon, 211 U. S. 127, 136, the Supreme Court of the United States declared: “When, in a great river like the Columbia, there are two substantial channels, and the proper authorities have named the center of one channel as the boundary between the States bordering on that river, the boundary, as thus prescribed, remains the boundary, subject to the changes in it which come by accretion, and is not moved to the other channel,

This

tinues to follow the line indicated by the previous channel.1 is true whether the river leaving its former bed thereby makes for itself a new course, or simply alters by enlargement or otherwise the path of the principal channel.2

If a State which is the territorial sovereign over lands on both sides of a river makes a grant of territory on one side of the stream, "it retains the river within its own domain, and the newly

although the latter in the course of years becomes the most important and properly called the main channel of the river."

Cf. opinion of Mr. Cushing, Attorney-General, 8 Ops. Attys.-Gen., 175; Cooley v. Golden, 52 Mo. App. 229; Nebraska v. Iowa, 143 U. S. 359; Missouri v. Nebraska, 196 U. S. 23; Buttenuth v. St. Louis Bridge Co., 123 Ill. 535, 546; Arkansas v. Tennessee, 246 U. S. 158, 173; Arkansas v. Mississippi, 250 U. S. 39, 44.

In Arkansas v. Tennessee, 246 U. S. 158, at 175, Mr. Justice Pitney, in the course of the opinion of the Court, adverting to the results of avulsion in causing the boundary to remain in the middle of the former channel, said: "An avulsion has this effect, whether it results in the drying up of the old channel or not. So long as that channel remains a running stream the boundary marked by it is still subject to be changed by erosion and accretion; but when the water becomes stagnant the effect of these processes is at an end; the boundary then becomes fixed in the middle of the channel as we have defined it, and the gradual filling up of the bed that ensues is not to be treated as an accretion to the shores but as an ultimate effect of the avulsion. The emergence of the land, however, may or may not follow, and it ought not in reason to have any controlling effect upon the location of the boundary line in the old channel." See, also, Whiteside v. Norton, 205 Fed. 5.

2 In the case of Nebraska v. Iowa, 143 U. S. 359, the Supreme Court of the United States held that while there might be an instantaneous and obvious erosion on one side of the Missouri River, if the accretion to the other side was gradual and imperceptible by alluvial deposits, the boundary would follow the changes in the channel thus effected notwithstanding their rapidity.

In the case of the Chamizal Arbitration before the Special International Boundary Commission, under the convention between the United States and Mexico of June 24, 1910, a grave problem arose concerning the interpretation of the boundary convention between those countries of Nov. 12, 1884, relating to the Rio Grande and Rio Colorado. Art. I of that convention provided that the dividing line should follow the center of the normal channel of those rivers irrespective of any alterations in their banks or courses, provided that such alterations were "effected by natural causes through the slow and gradual erosion and deposit of alluvium and not by the abandonment of an existing river bed and the opening of a new one." The presiding commissioner, Prof. La Fleur, and the Mexican commissioner, Mr. Puga, who constituted a majority of the tribunal, were of opinion that the language quoted signified that the boundary should not vary with alterations in the course of the Rio Grande in case of a rapid and obvious erosion even though there might be no abandonment of the river bed. The American commissioner, Gen. Mills, was, however, of opinion that it was impossible to impute to the contracting parties an intention to prevent the boundary from following changes in the course of the river in the case of rapid and perceptible erosion unless there was also an abandonment of the existing river bed. For the text of the award of the court and the dissenting opinion of the American commissioner, see Am. J., V, 782.

Art. 30 of the treaty of peace with Germany of June 28, 1919, entrusted to the boundary commissions provided by the treaty "to specify in each case whether the frontier line shall follow any changes of the course or channel which may take place, or whether it shall be definitely fixed by the position of the course or channel at the time when the present treaty comes into force."

erected State extends to the river only."1 Treaties have oftentimes recognized the fact that a river, instead of forming the boundary between two States, may be itself a part of the national domain of one riparian proprietor, the limit of whose territory is the further edge of the stream.2

When a river forms the boundary between two States, neither of them possesses the right to change, by means of artificial works or otherwise, the natural course of the thalweg, and so alter the line of demarcation or affect the navigability of the stream. It would be unjust, as was early perceived by Vattel,3 for one riparian proprietor so to promote its own advantage at its neighbor's expense. Numerous treaties give recognition to this principle. While they announce that lawful modification of a boundary by artificial means requires the consent of both the States concerned, they sometimes contemplate uses, obstructions or diversions to be made in accordance with the approval of a joint commission. It must be clear that no agreement of the States whose territories are divided by a river can render lawful acts on the part of either sovereign

1 Handly's Lessee v. Anthony, 5 Wheat. 374.

Writes Hall: "Upon whatever grounds property in the entirety of a stream or lake is established, it would seem in all cases to carry with it a right to the opposite bank as accessory to the use of the stream, and perhaps it even gives a right to a sufficient margin for defensive or revenue purposes, when the title is derived from occupation, or from a treaty of which the object is to mark out a political frontier." 5 ed., 123, quoted in Moore, Dig., I, 617, note.

2 Cf., for example, Art. III of the treaty between the United States and Spain of Feb. 22, 1819, relative to the boundary along the river Sabine, Malloy's Treaties, II, 1652; also texts of boundary conventions in the Argument of the United States in the Chamizal Arbitration, 21-24.

In the Argument of the United States in the Chamizal Arbitration there is noted (p. 24) a small group of European boundary treaties, which provide that the thalweg shall be designated at fixed points, which shall thereafter be regarded as forming a fixed line of demarcation, notwithstanding subsequent changes of the channel. The text of the boundary convention between Russia and Westphalia of May 14, 1811, is quoted. 3 Chitty's ed., § 271, p. 122. der Civilisirten Staaten, § 299; 4 See, for example, Arts. II, III, and IV of treaty between the United States and Great Britain respecting the boundary waters between the United States and Canada, Jan. 11, 1909, Charles' Treaties, 40-41, Am. J., IV, Supp., 239; Art. VII of treaty between the United States and Mexico, Feb. 2, 1848, Malloy's Treaties, I, 1111; Art. III of boundary convention between the United States and Mexico, Nov. 12, 1884, id., 1160; Art. V of boundary convention between the United States and Mexico, Mar. 1, 1889, id., 1168; Art. III of convention of limits between France and Prussia, Oct. 23, 1829, Brit. and For. State Pap., XVI, 907; convention between Sweden and Norway concerning common lakes and watercourses, Oct. 26, 1905, Nouv. Rec. Gén., 3 ser., XXXIV, 710, quoted in Bonfils-Fauchille, 7 ed., p. 358.

See, also, Bluntschli, Das Moderne Völkerrecht
Calvo, 5 ed., I, § 342, p. 466.

Cf., also, MS. Memorandum by William C. Dennis on "The effect of a gradual change in the thalweg of the Rio Grande caused by an artificial construction authorized by the Governments of the United States and Mexico, upon the international boundary line under the treaties between the two countries."