Table of Contents
2: Location, Borders, and Lakes
3: Geologic Structure and Landforms
6: Pre-historic and Early Historic Settlements
7: Survey Systems
8: Southern Hamlets, Villages, and Towns
9: Mennonite and Hutterite Settlements
10: First Nations Settlements
11: Northern Settlements
12: The Southern Cities
13: Mining and Oil Extraction
15: Industry / Manufacturing
16: Water Resources
17: Parks, Recreation, Sports
18: Transport and Communications: Past and Present
19: Legal Issues and Law Enforcement
16: Water Resources
Click for chapter introduction
Manitoba has an abundant supply of surface water with many large lakes and thousands of smaller ones (chapter 2). However, much of the water is in the north or drains to the north where there is a sparse population. In the south dams and reservoirs have been constructed to conserve water in some areas, whereas in other places projects were designed to drain water from the land to make it suitable for cultivation. The province’s rivers offered enormous potential for hydroelectric power, much of which has now been exploited, starting with a small-scale project on the Little Saskatchewan River and progressing to large projects on the Winnipeg, Saskatchewan and Nelson rivers. Two thermal power stations at Brandon and Selkirk on the Assiniboine and Red rivers illustrate the need for an assurred water supply. Flooding has been a problem since the earliest days of the province, especially along the Assiniboine and Red rivers culminating in the 1997 “Flood of the Century” in the Red River Valley. Dams, diversions and ring dikes are used to divert the floodwaters to less critical areas.
16.54: The Shellmouth Dam and Lake of the Prairies
The Shellmouth Dam 1 built across the Assiniboine River 2 and completed in 1967 is part of a three-pronged strategy—the Red River Floodway, and the Portage Floodway are the other two—to reduce flooding at Winnipeg. It also provides flood protection to Brandon and Portage la Prairie as well as ensuring a reliable flow during the summer through these cities that get their municipal water supply from the Assiniboine. The area has also become the location of an attractive provincial park—Asessippi Park—that provides opportunities for fishing, boating, camping, and associated activities. Blackbird Creek 3 and Bell Creek 4 flow into the Assiniboine from the north dissecting the north wall of the Assiniboine Glacial Spillway.
The dam backs up water into the Assiniboine 5 and Shell 6 valleys creating Lake of the Prairies 7 that extends north and west into Saskatchewan. The dam’s spillway can be seen at the northwest end 8, and a riparian channel 9 carries water into the meandering Assiniboine 10 which flows west then south past Shellmouth 11 located on a terrace 12 above the spillway floor.
The dam carries PR 482 13 across the Assiniboine; it then runs north 14 past Dropmore 15 and on into Saskatchewan. Another east/west gravel road 16 bends down the east wall of the spillway 17, and then passes through Shellmouth 18 and up the west wall of the spillway 19. The CN railway line 20—now abandoned—runs through Shellmouth; across the spillway 21, along the west side of Lake of the Prairies 22, and then past Dropmore 23 and into Saskatchewan.
This photo covers the Manitoba/Saskatchewan border 24 that runs along the 29/30WI range line. At the northern boundary of township 22, this line jogs west about 1¼ miles (2 km) 25. This jog is repeated every four townships north from the 49th parallel, starting at the township line between township 2 and township 3 and finishing at 56ºN, from where it is a straight line following the 106ºW line of longitude.[i]
Figure 16.54: The Shellmouth Dam and Lake of the Prairies
Vertical air photograph: A25047-21
Flight height: 24,700 feet a.s.l.; lens focal length: 6 inches
Scale: 1:50,700 (approx.)
Date: August 5, 1978
Location: Townships 22 and 23; Ranges 29 and 30WI
Map sheets: 1:250,000 62K Riding Mountain
1:50,000 62K/14 Inglis
[i] Welsted, J. “Straight or Crooked: An Assessment of Manitoba’s Boundaries” in The Yorkton Papers: Research by Prairie Geographers eds. J. Welsted and J. Everitt. Brandon: Brandon University, Department of Geography. 1997, 180-190.