The St. Mary Irrigation Project was first conceived as a commercial venture by the Canadian Northwest Irrigation Company, organized in 1892 by E.T. Galt of Lethbridge and financed with British capital. Later consolidated under the name of the Alberta Railway and Irrigation Company the organization took over a large block of land in the Magrath, Raymond, Lethbridge and Coaldale districts. This land was originally granted to the Galt Interests by the Government of Canada as subsidies for construction of the railways in the area.
The land was sold mainly to prospective Mormon settlers from Utah who had experience with irrigation, and construction of the irrigation works was largely accomplished by the settlers themselves. This included the establishment of a weir and headgate on the St. Mary River at Kimball with a canal leading to the Magrath and Lethbridge areas.
By 1901 it was possible to irrigate 3000 acres in the Magrath area and 600 acres near Lethbridge. By 1914 some 65,000 acres were irrigated and by 1942 a total of 127,000 acres in the Magrath, Raymond, Lethbridge, Coaldale, Stirling and Taber area were ready for irrigation. However, because of a lack of storage and irregular stream flows in late summer it was only possible to irrigate 120,000 acres, and then in many drier years the area experienced shortages of water.
Various schemes were proposed by the Reclamation Service of the Federal Government to provide storage for a project of about 500,000 acres and extensive surveys were undertaken by the organization between 1910 and 1920 but construction was not undertaken and the proposal were shelved for a later date.
In 1935 the Prairie Farm Rehabilitation Administration was organized by the Federal Government and strong petitions from irrigation farmers and other groups in the area of the project were made to the Federal Government. Further investigations by the P.F.R.A. indicated that benefits would not only accrue to the project area but to the whole country.
In 1938 W.L. (Wally) Foss was appointed P.F.R.A. Regional Engineer for Alberta to investigate various water resource schemes. He established an office in Calgary and began gathering a staff of engineers and technicians to investigate various schemes in the province. Included in the schemes was the St. Mary River Irrigation Project. Mr. Foss later was appointed Project Engineer for the St. Mary River Irrigation Project.
Early plans for the project included a dam on the Waterton River with a crossing of the St. Mary River to the irrigation area by a siphon.
Investigations started in 1938 indicated the location of a dam on the St. Mary River as well as the use of water from the Waterton and Belly Rivers would be a better solution to the water storage requirements. A site for the St. Mary Dam was located a few miles west of Spring Coulee and work went ahead for the design of the project. On October 15, 1945 the Federal Government announced that the St. Mary Dam would be built immediately. However, construction on the project started on October 4, 1945 on the Jensen (Pothole) Dam with funding provided by the Province of Alberta with the understanding that the Province would be reimbursed by the Federal Government.
Construction started on the St. Mary Dam in August 1946. The St. Mary Dam was officially opened on July 15, 1951 by the Right Honorable James G Gardiner, Minister of Agriculture for the Federal Government. Construction on the Belly River Diversion Structure commenced in 1956 and was completed in 1958. Construction on the Waterton Dam began in 1956 and was completed in 1964.
During the period of construction of the major structure of the Project work was proceeding on the main canal and distribution work to irrigate the land as far as Medicine Hat on the east. Originally the plan was to irrigate some 300,000 acres between St. Mary Dam and Medicine Hat by a low line canal and 200,000 acres by a highline canal and a canal to the east in the Milk River and Foremost areas. However, the advent of sprinkler irrigation resulted in the irrigation of about 465,000 acres under the original low line. This required the enlargement of the original low line canal and this was undertaken by the Province of Alberta. Plans to irrigate the lands under the high line canal and the east canal would not be possible unless additional water was made available.
The major headworks for the Project were operated by the P.F.R.A. of the Federal Government until April 1, 1974 when they were transferred to the Resource Management Division, Department of Environment, Government of Alberta. The St. Mary River Irrigation District maintains and operates the canals and reservoirs from Ridge Reservoir on the west to the eastern end of the Project at Medicine Hat. The major headworks up to Ridge Reservoir was paid for by the Government of Canada and the main canals and reservoirs from Ridge Reservoir east paid for by the Province of Alberta.
Statistics of Major Structure
The St. Mary's Dam
Height 62 metre (203 ft.)
Length 773 metres (2536 ft)
Base width 451 metres (1480 ft)
Length of Reservoir 27 Kilometers (16 miles)
Height 55 metres (180 ft)
Length S Kilometres (3 miles)
Base width 411 metres (1348 ft.
Waterton Reservoir to Belly River 8 kilometres (5 miles)
Belly River to St. Mary Reservoir 43 kilometres (26 miles)
St. Mary Reservoir to Ridge Reservoir 42 kilometres (25.4 miles)
Ridge Reservoir east 320 kilometres (192 miles)
Principal Storage Reservoirs (usable storage)
Waterton 114,000,000 cubic metres
St. Mary 357,000,000 cubic metres
Ridge 128,000,000 cubic metres
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