| Lake of the Prairies | |
|---|---|
| Shellmouth Reservoir | |
 Lake of the Prairies from the Shellmouth Dam | |
  Lake of the Prairies Location in Manitoba  Lake of the Prairies Lake of the Prairies (Canada) | |
| Location | R.M. of Shellmouth-Boulton / R.M. of Shell River, Manitoba and Cote No. 271, Saskatchewan |
| Coordinates | 51°08′40″N 101°30′19″W / 51.14444°N 101.50528°W |
| Type | reservoir |
| Primary inflows | Shell River |
| Primary outflows | Assiniboine River |
| Basin countries | Canada |
| Max. length | 56 km (35 mi) |
| Surface area | 61.5 km2 (23.7 sq mi) |
| Water volume | 480×106 m3 (390,000 acre⋅ft) |
| Surface elevation | 425 m (1,394 ft) |
| References | [1] |
Shellmouth Dam | |
 An aerial view of Shellmouth Dam and Reservoir | |
| Coordinates | 50°57′49″N 101°25′07″W / 50.96361°N 101.41861°W |
| Purpose | Multi-purpose |
| Status | Operational |
| Construction began | 1964 |
| Opening date | 1971 |
| Construction cost | $10.8 m CAD |
| Built by | Prairie Farm Rehabilitation Administration |
| Owner(s) | Government of Manitoba |
| Dam and spillways | |
| Type of dam | Embankment dam |
| Height (foundation) | 21.3 m (70 ft) |
| Width (crest) | 1,270 m (4,170 ft) |
| Website gov.mb.ca/mit/wms/shellmouth/ | |
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°57′49″N 101°25′07″W / 50.96361°N 101.41861°W) is a multi-purpose embankment dam built by the Prairie Farm Rehabilitation Administration (PFRA).[2]
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.[2] For example, in the 1997 Red River flood, the inflow to the reservoir peaked at 10,000 cubic feet per second (280 m3/s) while the outflow never exceeded 1,700 cu ft/s (48 m3/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.
- ^ "Manitoba Infrastructure: Shellmouth Dam and Reservoir". Government of Manitoba. Retrieved 22 November 2021.
- ^ a b c "Water Management and Structures | Infrastructure | Province of Manitoba". www.gov.mb.ca. Retrieved 7 August 2021.
- ^ "Flood Control Works". Prairiewaternews.ca. Archived from the original on 15 January 2013.