This Tribunal is constituted under, and its powers are derived from and limited by, the Convention between the United States of America and the Dominion of Canada signed at Ottawa, April 15, 1935, duly ratified by the two parties, and ratifications exchanged at Ottawa, August 3, 1935 (hereinafter termed "the Convention").
By Article II of the Convention, each Government was to choose one member of the Tribunal, "a jurist of repute", and the two Governments were to choose jointly a Chairman who should be a "jurist of repute and neither a British subject nor a citizen of the United States".

The members of the Tribunal were chosen as follows: by the United States of America, Charles Warren of Massachusetts ; by the Dominion of Canada, Robert A. E. Greenshields of the Province of Quebec; by the two Governments jointly, Jan Frans Hostie of Belgium.

Article II, paragraph 4, of the Convention provided that "the Governments may each designate a scientist to assist the Tribunal"; and scientists were designated as follows: by the United States of America, Reginald S. Dean of Missouri; and by the Dominion of Canada, Robert E. Swain of California. The Tribunal desires to record its appreciation of the valuable assistance received by it from these scientists.

The duty imposed upon the Tribunal by the Convention was to "finally decide" the following questions:

1912 The Tribunal met in Washington, in the District of Columbia, on June 21, 22, 1937, for organization, adoption of rules of procedure and hearing of preliminary statements. From July 1 to July 6, it travelled over and inspected the area involved in the controversy in the northern part of Stevens County in the State of Washington and it also inspected the smelter plant of the Consolidated Mining and Smelting Company of Canada, Limited, at Trail in British Columbia. It held sessions for the reception and consideration of such evidence, oral and documentary, as was presented by the Governments or by interested parties, as provided in Article VIII, in Spokane in the State of Washington, from July 7 to July 29, 1937; in Washington, in the District of Columbia, on August 16, 17, 18, 19, 1937; in Ottawa, in the Province of Ontario, from August 23 to September 18, 1937; and it heard arguments of counsel in Ottawa from October 12 to October 19, 1937.

On January 2, 1938, the Agents of the two Governments jointly informed the Tribunal that they had nothing additional to present. Under the provisions of Article XI of the Convention, it then became the duty of the Tribunal "to report to the Governments its final decisions . . . . and within a period of three months after the conclusion of the proceedings", i.e., on April 2, 1938". 

After long consideration of the voluminous typewritten and printed record and of the transcript of evidence presented at the hearings, the Tribunal formally notified the Agents of the two Governments that, in its opinion, unless the time limit should be extended, the Tribunal would be forced to give a permanent decision on April 2, 1938, on the basis of data which it considered inadequate and unsatisfactory. Acting on the recommendation of the Tribunal and under the provisions of Article XI authorizing such extension, the two Governments by agreement extended the time for the report of final decision of the Tribunal to three months from October 1, 1940.

The Tribunal is prepared now to decide finally Question No. 1, propounded to it in Article III of the Convention; and it hereby reports its final decision on Question No. 1, its temporary decision on Questions No. 2 and No. 3, and provides for a temporary régime thereunder and for a final decision on these questions and on Question No. 4, within three months from October 1, 1940.

Wherever, in this decision, the Tribunal has referred to decisions of American courts or has followed American law, it has acted pursuant to Article IV as follows: "The Tribunal shall apply the law and practice followed in dealing with cognate questions in the United States of America . . . ."

In all the consideration which the Tribunal has given to the problems presented to it, and in all the conclusions which it has reached, it has been guided by that primary purpose of the Convention expressed in the words of Article IV, that the Tribunal "shall give consideration to the desire of the high contracting parties to reach a solution just to all parties concerned", and further expressed in the opening paragraph of the Convention as to the "desirability and necessity of effecting a permanent settlement" of the controversy.

The controversy is between two Governments involving damage occurring in the territory of one of them (the United States of America) and alleged to be due to an agency situated in the territory of the other (the Dominion of Canada), for which damage the latter has assumed by the Convention an international responsibility. In this controversy, the Tribunal is not sitting to pass upon claims presented by individuals or on behalf of one or more individuals by their Government, although individuals may come within the meaning of "parties concerned", in Article IV and of

1913 "interested parties", in Article VIII of the Convention and although the damage suffered by individuals may, in part, "afford a convenient scale for the calculation of the reparation due to the State" (see Jugdment No. 13, Permanent Court of International Justice, Series A, No. 17, pp. 27, 28).

By way of introduction to the Tribunal's decision, a brief statement, in general terms, of the topographic and climatic conditions and economic history of the locality involved in the controversy may be useful.
The Columbia River has its source in the Dominion of Canada. At a place in British Columbia named Trail, it flows past a smelter located in a gorge, where zinc and lead are smelted in large quantities. From Trail, its course is easterly and then it swings in a long curve to the International Boundary Line, at which point it is running in a southwesterly direction; and its course south of the boundary continues in that general direction. The distance from Trail to the boundary line is about seven miles as the crow flies or about eleven miles, following the course of the river (and possibly a slightly shorter distance by following the contour of the valley). At Trail and continuing down to the boundary and for a considerable distance below the boundary, mountains rise on either side of the river in slopes of various angles to heights ranging from 3,000 to 4,500 feet above sea-level, or between 1,500 to 3,000 feet above the river. The width of the valley proper is between one and two miles. On both sides of the river are a series of bench lands at various heights.
More or less half way between Trail and the boundary is a place, on the east side of the river, known as Columbia Gardens; at the boundary on the American side of the line and on the east side of the river, is a place known as Boundary; and four or five miles south of the boundary on the east bank of the river is a farm named after its owner, Stroh farm. These three places are specially noted since they are the locations of automatic sulphur dioxide recorders installed by one or other of the Governments. The town of Northport is located on the east bank of the river, about nineteen miles from Trail by the river, and about thirteen miles as the crow flies, and automatic sulphur dioxide recorders have been installed here and at a point on the west bank northerly of Northport. It is to be noted that mountains extending more or less in an easterly and westerly direction rise to the south between Trail and the boundary.
Various creeks are tributary to the river in the region of Northport, as follows: Deep Creek flowing from southwest to northwest and entering the river slightly north of Northport; opposite Deep Creek and entering on the west side of the river and flowing from the northwest, Sheep Creek; north of Sheep Creek on the west side, Nigger Creek; south of Sheep Creek on the west side, Squaw Creek; south of Northport, on the east side, flowing from the southeast, Onion Creek.
About eight miles south of Northport, following the river, is the town of Marble; and about seventeen miles, the town of Bossburg. Three miles south of Bossburg is the town of Evans; and about nine miles, the town of Marcus. South of Marcus and about forty-one miles from the boundary line is the town of Kettle Falls which, in general, may be stated to be the southern limit of the area as to which evidence was presented. All the above towns are small in population and in area.1914 At Marble and to the south, various other creeks enter the river from the west side—Rattlesnake Creek, Crown Creek, Flat Creek, and Fifteen Mile Creek.
Up all the creeks above mentioned, there extend tributary valleys, differing in size.
While, as stated above, the width of the valley proper of the river is from one to two miles, the width of the valley measured at an altitude of 3,000 feet above sea-level, is approximately three miles at Trail, two and one-half miles at Boundary, four miles above Northport, three and one-half miles at Marble. Near Bossburg and southward the valley at the same altitude broadens out considerably.
As to climatic conditions, it may be stated that the region is, in general, a dry one though not what is termed "arid". The average annual precipitation at Northport from 1923 to 1936 inclusive averaged slightly below seventeen inches. It varied from a minimum of 9.60 inches in 1929 to a maximum of 26.04 inches in 1927. The average crop-year precipitation over the same period is slightly over sixteen inches, with a variation from a minimum of 10.10 inches in 1929 to a maximum of 24.01 in 1927. The rainfall in the growing-season months of April, May and June at Northport, has been in 1932, 5.43 inches; in 1933, 3.03 inches; in 1934, 2.74 inches; in 1933, 2.02 inches; in 1929, 4.44 inches. The average snowfall was reported in 1915 by United States Government agents as fifty-eight inches at Northport. The average humidity varies with some regularity from day to day. In June, 1937, at Northport, it had an average maximum of 74 per cent at 5 a.m. and an average minimum of 26 per cent at 5 p.m.
The range of temperature in the different months as it appears from the records of the years 1934, 1935, and 1936, at Northport was as follows: In the months of November, December, January and February, the lowest temperature was 1° (in January, 1936), and the highest was 60° (in November 1934); in the growing-season months of April, May, June and July, the lowest temperature was 12° (in April, 1936), and the highest was 110° (in July, 1934); in the remaining months of August, September, October and March, the lowest temperature was 8° (in October, 1935), and the highest was 102° (in August, 1934).
The direction of the surface wind is, in general, from the northeast down the river valley, but this varies at different times of day and in different seasons. The subject of winds is treated in detail in a later part of this decision and need not be considered further at this point.
The history of what may be termed the economic development of the area may be briefly stated as follows: Previous to 1892, there were few settlers in this area, but homesteading and location of farms received an impetus, particularly on the east side of the river, at the time when the construction of the Spokane and Northern Railway was undertaken, which was completed between the City of Spokane and Northport in 1892, and extended to Nelson in British Columbia in 1893. In 1892, the town of Northport was founded. The population of Noithport, according to the United State: Census in 1900, was 787; in 1910, it was 476; in 1920, it was 906; and in 1930, it was 391. The population of the area which may be termed, in general, the "Northport Area", according to the United States Census in 1910, was 1,448; in 1920, it was 2,142; and in 1930, it was 1,121. The population of this area as divided into the Census Precincts was as follows:1915

(It is to be noted that the precincts immediately adjacent to the boundary line were Frontier, Nigger Creek and Boundary; and that Frontier and Nigger Creek Precincts are at the present time included in the Northport Precinct.)
The area of all land in farms in the above precincts, according to the United States Census of Agriculture in 1925 was 21,551 acres; in 1930, 28,641 acres; and in 1935, 24,772 acres. The area in crop land in 1925 was 3,474 acres ; in 1930, 4,285 acres ; and in 1933, 4,568 acres. The farm population in 1925 was 496; in 1930, 603; and in 1935, 466.
In the precincts nearest the boundary line, viz., Boundary and Northport (including Frontier and Nigger Creek prior to 1935 Census), the area of all land in farms in 1925 was 5,292 acres; in 1930, 8,040 acres; and in 1935, 5,666 acres. The area in crop land in 1925 was 798 acres; in 1930, 1,227 acres; and in 1935, 963 acres. The farm population in 1925 was 149; in 1930, 193; and in 1935, 145.
About the year 1896, there was established in Northport a business which has been termed the "Breen Copper Smelter", operated by the LeRoi Mining and Smelting Company, and later carried on by the Northport Smelting and Refining Company which was chartered in 1901. This business employed at times from five hundred to seven hundred men, although, as compared with a modern smelter like the Trail Smelter, the extent of its operations was small. The principal value of the ores smelted by it was in copper, and the ores had a high sulphur content. For some years, the somewhat primitive method of "heap roasting" was employed which consisted of roasting the ore in open piles over woodfires, frequently called in mining parlance, "stink piles". Later, this process was changed. About seventy tons of sulphur were released per day. This Northport Smelting and Refining Company intermittently continued operations until 1908. From 1908 until 1915, its smelter lay idle. In March, 1916, during the Great War, operation was resumed for the purpose of smelting lead ore, and continued until March 5, 1921, when it ceased business and its plant was dismantled. About 30 tons of sulphur per day were emitted during this time. There is no doubt that damage was caused to some extent over a more or less restricted area by the operation of this smelter plant.
The record and evidence placed before the Tribunal does not disclose in detail claims for damage on account of fumigations which were made between 1896 and 1908, but it does appear that there was considerable litigation in Stevens County courts based on such claims. It also appears in evidence that prior to 1908, the company had purchased smoke easements from sixteen owners of land in the vicinity covering 2,330 acres. It further appears that from 1916 to 1921, claims for damages were made and suits 1916 were brought in the courts, and additional smoke easements were purchased from thirty-four owners of land covering 5,556.7 acres. These various smoke easements extended to lands lying four or five miles north and three miles south and three miles east of Northport and on both sides of the river, and they extended as far as the boundary line.
In addition to the smelting business, there have been intermittent mining operations of lead and zinc in this locality, but they have not been a large factor in adding to the population.
The most important industry in the area in the past has been the lumber industry. It had its beginning with the building of the Spokane & Northern Railway. Several saw mills were constructed and operated, largely for the purpose of furnishing ties to the railway. In fact, the growing trees— yellow pine, Douglas fir, larch, and cedar—were the most valuable asset to be transformed into ready cash. In early days, the area was rather heavily wooded, but the timber has largely disappeared and the lumber business is now of small size. It appears from the record in 1929 that, within a radius covering some thirty-five thousand acres surrounding Northport, fifteen out of eighteen sawmills had been abandoned and only three of the small type were in operation. The causes of this condition are in dispute. A detailed description of the forest conditions is given in a later part of this decision and need not be further discussed here.
As to agricultural conditions, it may be said that farming is carried on in the valley and upon the benches and mountain slopes and in the tributary valleys. The soils are of a light, sandy nature, relatively low in organic matter, although in the tributary valleys the soil is more loamy and fertile. In some localities, particularly on the slopes, natural sub-irrigation affords sufficient moisture; but in other regions irrigation is desirable in order to produce favorable results. In a report made by Dr. F. C. Wyatt, head of the Soils Department of the University of Alberta, in 1929, it is stated that "taken as a unit, the crop range of these soils is wide and embraces the crops suited to the climate conditions. Under good cultural operations, yields are good." At the same time, it must be noted that a large portion of this area is not primarily suited to agriculture. In a report of the United States Department of Agriculture, in 1913, it is stated that "there is approximately one-third of the land in the Upper Columbia Basin unsuited for agricultural purposes, either because it is too stony, too rough, too steep, or a combination of these factors. To utilize this large proportion of land and to meet the wood needs of an increasing population, the Upper Columbia Basin is forced to consider seriously the problem of reforestation and conservation." Much of the farming land, especially on the benches, is land cleared from forest growth ; most of the farms contain from an eighth to a quarter of a section (80-160 acres); and there are many smaller and some larger farms.
In general, the crops grown on the farms are alfalfa, timothy, clover, grain cut green for hay, barley, oats, wheat, and a small amount of potatoes. Wild hay is cut each year to some extent. The crops, in general, are grown for feed rather than for sale, though there is a certain amount of wheat and oats sold. Much of the soil is apparently well suited to the predominant crop of alfalfa, which is usually cut at present twice a year (with a small third crop on some farms). Much of the present alfalfa has been rooted for a number of years.
Milch cattle are raised to a certain extent and they are grazed on the wild grasses on the hills and mountains in the summer months, but the dairying 1917 business depends on existence of sufficient land under cultivation as an adjunct to the dairy to provide adequate forage for the winter months.
In early days, it was believed that, owing to soil and climatic conditions, this locality was destined to become a fruit-growing region, and a few orchards were planted. For several reasons, of which it is claimed that fumigation is one, orchards have not thrived. In 1909-1910, the Upper Columbia Company purchased two large tracts, comprising about ten thousand acres, with the intention of developing the land for orchard purposes and selling of timber in the meantime, and it established a large orchard of about 900 acres in the town of Marble. The project, as early as 1917, proved a failure.
In 1896, a smelter was started undei American auspices near the locality known as Trail. In 1906, the Consolidated Mining and Smelting Company of Canada, Limited, obtained a charter of incorporation from the Canadian authorities, and that company acquired the smelter plant at Trail as it then existed. Since that time, the Canadian Company, without interruption, has operated the Smelter, and from time to time has greatly added to the plant until it has become one of the best and largest equipped smelting plants on this continent. In 1925 and 1927, two stacks of the plant were erected to 409 feet in height and the Smelter greatly increased its daily smelting of zinc and lead ores. This increased product resulted in more sulphur dioxide fumes and higher concentrations being emitted into the air; and it is claimed by one Government (though denied by the other) that the added height of the stacks increased the area of damage in the United States. In 1916, about 5,000 tons of sulphur per month were emitted; in 1924, about 4,700 tons; in 1926, about 9,000 tons—an amount which rose near to 10,000 tons per month in 1903. In other words, about 300-350 tons of sulphur were being emitted daily in 1930. (It is to be noted that one ton of sulphur is substantially the equivalent of two tons of sulphur dioxide or SO2.)
From 1925, at least, to the end of 1931, damage occurred in the State of Washington, resulting from the sulphur dioxide emitted from the Trail Smelter.
As early as 1925 (and there is some evidence earlier) suggestions were made to the Trail Smelter that damage was being done to property in the northern part of Stevens County. The first formal complaint was made, in 1926, by one J. H. Stroh, whose farm (mentioned above) was located a few miles south of the boundary line. He was followed by others, and the Smelter Company took the matter up seriously and made a more or less thorough and complete investigation. This investigation convinced the Trail Smelter that damage had been and was being done, and it proceeded to negotiate with the property owners who had made complaints or claims with a view to settlement. Settlements were made with a number of farmers by the payment to them of different amounts. This condition of affairs seems to have lasted during a period of about two years. In June, 1928, the County Commissioners of Stevens County adopted a resolution relative to the fumigations; and on August 25, 1928, there was brought into existence an association known as the "Citizens' Protective Association". Due to the creation of this association or to other causes, no settlements were made thereafter between the Trail Smelter and individual claimants, as the articles of association contained a provision that "no member herein shall make any settlement for damages sought to be secured herein, unless the written consent of the majority of the Board of Directors shall have been first obtained". 1918 It has been contended that either by virtue of the Constitution of the State of Washington or of a statute of that State, the Trail Smelter (a Canadian corporation) was unable to acquire ownership or smoke easements over real estate, in the State of Washington, in any manner. In regard to this statement, either as to the fact or as to the law, the Tribunal expresses no opinion and makes no ruling.
The subject of fumigations and damage claimed to result from them was first taken up officially by the Government of the United States in June, 1927, in a communication from the Consul General of the United States at Ottawa, addressed to the Government of the Dominion of Canada.
In December, 1927, the United States Government proposed to the Canadian Government that problems growing out of the operation of the Smelter at Trail should be referred to the International Joint Commission, United States and Canada, for investigation and report, pursuant to Article IX of the Convention of January 11, 1909, between the United States and Great Britain. Following an extensive correspondence between the two Governments, they joined in a reference of the matter to that Commission under date of August 7, 1928. It may be noted that Article IX of the Convention of January 11, 1909, provides that the high contracting parties might agree that "any other question or matters of difference arising between them involving the rights, obligations or interests of either in relation to the other, or to the inhabitants of the other, along the common frontier between the United States and the Dominion of Canada shall be referred from time to time to the International Joint Commission for examination and report. . . . Such reports shall not be regarded as decisions of the question or matters so submitted either on the facts or on the law, and shall not, in any way, have the character of an arbitral award."
The questions referred to the International Joint Commission were five in number, the first two of which may be noted: First, the extent to which property in the State of Washington has been damaged by fumes from Smelter at Trail, B.C. ; second, the amount of indemnity which would compensate United States interests in the State of Washington for past damages.
The International Joint Commission sat at Northport to take evidence and to hear interested parties in October, 1928; in Washington, D.C., in April, 1929; at Nelson in British Columbia in November, 1929; and final sittings were held in Washington, D.C, on January 22 and February 12, 1930. Witnesses were heard; reports of the investigations made by scientists were put in evidence; counsel for both the United States and Canada were heard, and briefs submitted; and the whole matter was taken under advisement by the Commission. On February 28, 1931, the Report of the Commission was signed and delivered to the proper authorities. The report was unanimous and need not be considered in detail.
Paragraph 2 of the report, in part, reads as follows:

In view of the anticipated reduction in sulphur fumes discharged from the Smelter at Trail during the present year, as hereinafter referred to, the Commission therefore has deemed it advisable to determine the amount of indemnity that will compensate United States interests in respect of such fumes, up to and including the first day of January, 1932. The Commission finds and determines that all past damages and all damages up to and including the first day of January next, is the sum of $350,000. Said sum, however, shall not include any damage occurring after January 1, 1932.