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 Reservoir27 Kilometers (16 miles)

Waterton Dam
Height 55 metres (180 ft)
Length S Kilometres (3 miles)
Base width 411 metres (1348 ft.

Main Canals
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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