Procedures for the Division of the Waters of the St. Mary and Milk Rivers


The division of the waters of the St. Mary River and Milk River, including its tributaries, is governed by the Boundary Waters Treaty of 1909 which specifies the proportion of the natural flow to which each country is entitled. The subsequent Order of the International Joint Commission (IJC) dated October 4, 1921, gives general procedural guidelines for determining natural flow.

The intent of this report is to:
1. Document the procedures and assumptions used in determining natural flow.
2. Document the reasoning for certain procedures or assumptions.
3. Act as a user's manual for determining the natural flow on an interim and annual basis.

United States Geological Survey, Department of the Interior, Helena, Montana and Water Survey Division, Meteorological Service of Canada, Environment and Climate Change Canada, Calgary, Alberta and Regina, Saskatchewan