Overview

This treaty governs the sharing of waters of international streams between Canada and the United States and established an International Joint Commission (IJC) to monitor compliance and resolve disputes.

The IJC held four public information sessions in 2004, to gather information on the sharing of the Milk and St. Mary Rivers.

Later that year, the commission established the International St. Mary/ Milk Rivers Administrative Measures Task Force, with four members each from Canada and the United States.

The task force released a draft report in April 2006 for public comment, available on the commission's website.

To view a summary of Alberta's perspective on the task force report, and the Government of Alberta's formal submission to the task force, see the following:

Background:

The Government of Alberta (August 2004) submission to the IJC consisted of an overall submission as well as submissions from Alberta Agriculture, Food and Rural Development (now Alberta Agriculture and Forestry) and Alberta Environment (now Alberta Environment and Parks).

Milk River

Originating in the foothills of western Montana and flowing northeast into Alberta near Del Bonita, the Milk River flows due east for about 170 km across southern Alberta before re-entering eastern Montana. Sharing of its waters is governed by Article VI of the Boundary Waters Treaty (1909), and the 1921 Order of the International Joint Commission. These agreements entitle Canada (Alberta) to receive the following quantities of the natural flow of the St. Mary River at its crossing of the International Boundary:

Non-irrigation season (November 1 to March 31)

  • 50% of the natural flow

Irrigation season (April 1 to October 31)

For natural flow rate up to 18.86 m³/s (666 cubic feet per second (cfs)):

  • 25% of the natural flow

For natural flow rates in excess of 18.86 m³/s (666 cfs):

  • a prior allocation of 4.71 m³/s (166.5 cfs) plus 50% of the natural flow above 18.86 m³/s (666 cfs)

The annual natural flow of the Milk River during the irrigation season and the annual entitlements for Canada (Alberta) and the U.S. can be seen in the Milk River Apportionment Data.

St. Mary River

Originating in northwestern Montana on the eastern slopes of the Rocky Mountains, the river flows northeast across the International Boundary into Alberta, emptying into the Oldman River near Lethbridge. Sharing of the waters is governed by Article VI of the Boundary Waters Treaty (1909) and the 1921 Order of the International Joint Commission.

Under these agreements Canada (Alberta) is entitled the receive the following quantities of the natural flow of the St. Mary River at its crossing of the International Boundary:

Non-irrigation season (November 1 to March 31)

  • 50% of the natural flow

Irrigation season (April 1 to October 31)

For natural flow rate up to 18.86 m³/s (666 cubic feet per second (cfs)):

  • 75% of the natural flow

For natural flow rates in excess of 18.86 m³/s (666 cfs):

  • a prior allocation of 14.16 m³/s (500 cfs) plus 50% of the natural flow above 18.86 m³/s (666 cfs)

Compliance

Compliance during the irrigation season is computed on a semi-monthly basis, with any shortfalls due in the next balancing period. Surplus deliveries by the upstream jurisdiction cannot be banked or used to offset future delivery shortfalls.

As water uses are relatively minor during the non-irrigation season, compliance is currently not monitored for this period.

Apportionment data

The irrigation and non-irrigation season natural flow volumes for the St. Mary River at the International Boundary along with Canadian (Alberta) and U.S. entitlements and the flow actually received by Canada can be seen in the St. Mary River Apportionment Data.

Contact

Connect with the Transboundary Waters Secretariat:
Email: aep.tws@gov.ab.ca

Related

Transboundary Waters Secretariat – Factsheet