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Chapter 16: Water Resources

16.52: The Portage Dam and Diversion

A dam has been built across the Assiniboine River above Portage la Prairie to divert water into a floodway at times of high flow, thus reducing the possibility of flooding at Portage la Prairie and Winnipeg. On this large-scale, colour infrared photo, the dam 1, a spillway 2, and the beginning of the floodway 3 can be seen. The dam backs up water necessitating the building of a dike 4 to prevent flooding of nearby agricultural land 5. The blue/green colour of the Assiniboine 6 indicates that it has a high suspended sediment load, and in one location 7 the pink colour indicates that algae are growing in a stagnant area.

Note also the following: 1) meander scrolls are visible south of the river 8 indicating previous river positions and influencing crop growth. Areas of poor growth which are almost white have a linear form 9 corresponding to the shape of the scrolls; 2) deciduous trees are red, have a mottled texture 10, and throw rounded shadows 11; 3) narrow fields east of the river channel 12 reflect the influence of the long lot system of land division used in this area; and 4) the twinned Trans-Canada Highway with service roads on both sides 13 cuts across the northeast corner.

Figure 16.52: The Portage Dam and Diversion

Figure 16.52: The Portage Dam and Diversion

Figure 16.52

Vertical colour infrared photograph

Prairie Agri Photo

Scale: 1:9,400 (approx.)

Date: June 1986

Location: Township 11; Range 7 WI

Map sheets: 1:250,000 62G Brandon

                    1:50,000 62G/16 Portage la Prairie