The Saint Mary River (), is a cross-border

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

of the

Oldman River The Oldman River is a river in southern Alberta, Canada. It flows roughly west to east from the Rocky Mountains, through the communities of Fort Macleod, Lethbridge, and on to Grassy Lake, where it joins the Bow River to form the South Sa ...

, itself a tributary of the

South Saskatchewan River The South Saskatchewan River is a major river in the Canadian provinces of Alberta and Saskatchewan. The river begins at the confluence of the Bow River, Bow and Oldman Rivers in southern Alberta and ends at the Saskatchewan River Forks in ce ...

. The Saint Mary together with the

Belly River Belly River is a river in northwest Montana, United States and southern Alberta, Canada. It is a tributary of the Oldman River, itself a tributary of the South Saskatchewan River. The name of the river may come from the Blackfoot word of , mea ...

and

Waterton River Waterton Lake () is a mountain lake in southern Alberta, Canada, and northern Montana, United States. The lake is composed of two bodies of water, connected by a shallow channel known locally as the Bosporus. The two parts are referred to as Middl ...

drains a small portion of

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

, in the United States, to the

Hudson Bay Hudson Bay, sometimes called Hudson's Bay (usually historically), is a large body of Saline water, saltwater in northeastern Canada with a surface area of . It is located north of Ontario, west of Quebec, northeast of Manitoba, and southeast o ...

watershed in Canada. The river rises as a stream on

Gunsight Mountain Gunsight Mountain is a prominent elevation summit located northeast of Palmer in the Talkeetna Mountains of the U.S. state of Alaska. This landmark is set midway between Palmer and Glennallen, with the Glenn Highway traversing the southern bas ...

in Glacier National Park and flows into Gunsight Lake, then flows into

Saint Mary Lake Saint Mary Lake is the second-largest lake in Glacier National Park (U.S.), Glacier National Park, in the U.S. state of Montana. Located on the east side of the park, Going-to-the-Sun Road parallels the lake along its north shore. At an elevatio ...

, exits the park and flows on into Lower St. Mary Lake in the

Blackfeet Indian Reservation The Blackfeet Nation (, ), officially named the Blackfeet Tribe of the Blackfeet Indian Reservation of Montana, is a federally recognized tribe of Siksikaitsitapi people with an Indian reservation in Montana. Tribal members primarily belong ...

. From the reservation, the St. Mary River flows into

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

and into the St. Mary Reservoir. It flows into the Oldman River which eventually reaches the Saskatchewan River. It passes near the town of

Cardston, Alberta Cardston is a town in Alberta, Canada. It was first settled in 1887 by members of the Church of Jesus Christ of Latter-day Saints (LDS Church) who travelled from Utah, via the Macleod-Benton Trail, to present-day Alberta in one of the century ...

, and the city of

Lethbridge Lethbridge ( ) is a city in the province of Alberta, Canada. With a population of 106,550 in the 2023 Alberta municipal censuses, 2023 municipal census, Lethbridge became the fourth Alberta city to surpass 100,000 people. The nearby Canadian ...

, Alberta.

Irrigation

The St. Mary River also provides water for irrigation in Southern Alberta. The St. Mary River Irrigation District (SMRID) is Canada’s largest

irrigation district In the United States an irrigation district is a cooperative, self-governing public corporation set up as a subdivision of the State government, with definite geographic boundaries, organized, and having taxing power to obtain and distribute water ...

delivering water through of canals and pipelines to approximately of land south of the Oldman and South Saskatchewan Rivers between Lethbridge and

Medicine Hat Medicine Hat is a city in Southern Alberta, southeast Alberta, Canada. It is located along the South Saskatchewan River. It is approximately east of Lethbridge and southeast of Calgary. This city and the adjacent Town of Redcliff, Alberta, R ...

. The irrigation project was started in 1898, and on September 4, 1900, the first water was brought to

by the project. In December 1945 the

Canadian Pacific Railway The Canadian Pacific Railway () , also known simply as CPR or Canadian Pacific and formerly as CP Rail (1968–1996), is a Canadian Class I railway incorporated in 1881. The railway is owned by Canadian Pacific Kansas City, Canadian Pacific Ka ...

transferred control of the projects to the government of Alberta, creating the St. Mary and Milk River Development (SMRD). A dam was created in 1946 on the St. Mary River, to service the irrigation system, and water finally reached Medicine Hat in 1954 upon the completion of the St. Mary Main Canal.

Notes

{{DEFAULTSORT:St. Mary River (Alberta-Montana) Landforms of Glacier National Park (U.S.) International rivers of North America Irrigation districts Irrigation in Canada Rivers of Glacier County, Montana Rivers of Alberta Rivers of Montana Lewis Range South Saskatchewan River Tributaries of Hudson Bay

Irrigation

See also

Notes