Historical Society

Did You Know?

St. Mary and Milk River Agreement of 1921

In 1909, the Boundary Waters Treaty was drafted between Canada and the United States.

While the 1909 Treaty outlined that the St. Mary and Milk Rivers and their tributaries were to be treated as one stream and shared equally between the two countries, the reclamation and irrigation officers weren’t able to agree as to how the water should be measured and divided up between the countries.

So the International Joint Commission (IJC) was formed and part of its work was to settle the matter. On 4 October 1921, the IJC brought forward an order about how the waters would be divided and when and how measurements would be made.

The apportionment of the water differed between irrigation and non-irrigation seasons and was also dependent on the amount of the natural flow of each river. It carefully set out what fraction of the water each country was due. The six members of the IJC in 1921, with three members representing each country, were: C.A. Magrath, C.D. Clark, Henry A. Powell, O. Gardner, W.H. Hearst, and Mark A. Smith. Charles Magrath, first Mayor of Lethbridge and a surveyor by training, was appointed to the IJC in 1911 and served as chair of the Canadian contingent from 1915 to 1936.

Lethbridge Historical Society

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Photograph: Cowboys cooling off in the Milk River, 1912.