| Lake of the Prairies | |||||||||||||||||||||||||||||
| Location: | R.M. of Shellmouth-Boulton / R.M. of Shell River, Manitoba and Cote No. 271, Saskatchewan | ||||||||||||||||||||||||||||
| Coords: | 51.1444°N -101.5053°W | ||||||||||||||||||||||||||||
| Type: | reservoir | ||||||||||||||||||||||||||||
| Inflow: | Shell River | ||||||||||||||||||||||||||||
| Outflow: | Assiniboine River | ||||||||||||||||||||||||||||
| Basin Countries: | Canada | ||||||||||||||||||||||||||||
| Pushpin Map: | Manitoba#Canada | ||||||||||||||||||||||||||||
| Pushpin Map Caption: | Location in Manitoba | ||||||||||||||||||||||||||||
| Length: | 56km (35miles) | ||||||||||||||||||||||||||||
| Area: | 61.5km2 | ||||||||||||||||||||||||||||
| Volume: | 480e6m3 | ||||||||||||||||||||||||||||
| Elevation: | 425m (1,394feet) | ||||||||||||||||||||||||||||
| Other Name: | Shellmouth Reservoir | ||||||||||||||||||||||||||||
| Reference: | [1] | ||||||||||||||||||||||||||||
| Module: |
| ||||||||||||||||||||||||||||
The Shellmouth Reservoir (also known as Lake of the Prairies) is a man-made reservoir on the Assiniboine River in Manitoba and Saskatchewan, Canada.[2]
The Shellmouth Dam (50.9636°N -101.4186°W) is a multi-purpose embankment dam built by the Prairie Farm Rehabilitation Administration (PFRA).
The dam and reservoir are part of a strategy to reduce the risk of flood damage for Winnipeg and other communities along the Assiniboine River. For example, in the 1997 Red River flood, the inflow to the reservoir peaked at 10000cuft/s while the outflow never exceeded 1700cuft/s.[3] The reservoir is also used to supplement flows on the Assiniboine when conditions are dry, ensuring water supply for Brandon, Portage la Prairie, irrigators, and some industries. For example in early August, 2021 the flow in Brandon was a little over 9 m3/s while the outflow from Shellmouth was 5.7 m3/s and inflow was less than 0.5 m3/s. Therefore without the dam the flow in the Assiniboine at Brandon would be a bit under 4 m3/s.
Asessippi Provincial Park is established around the southern arm of the lake.
The dam is 70feet high and 4200feet long.
The reservoir is 35miles in length and stores 390,000 acre feet (480 million cubic metres) at the spillway crest level of 1408.5feet. Outflows are controlled by a gated conduit and a 210feet wide concrete chute spillway. The normal summer level target is between 1400feet and 1404feet.
Fish species include walleye, yellow perch, northern pike, mooneye, burbot, rock bass, brown bullhead, white sucker, shorthead redhorse and common carp. Rock bass are Saskatchewan's only native bass.