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]

Lake of the Prairies
Shellmouth Reservoir
Lake of the Prairies from the Shellmouth Dam
Lake of the Prairies
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
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	480×10^6 m3 (390,000 acre⋅ft)
Surface elevation	425 m (1,394 ft)
References	[1]
Dam Shellmouth Dam
An aerial view of Shellmouth Dam and Reservoir
Coordinates	50°57′49″N 101°25′07″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 Dam (50°57′49″N 101°25′07″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 cms while the outflow from Shellmouth was 5.7 cms and inflow was less than 0.5 cms. Therefore without the dam the flow in the Assiniboine at Brandon would be a bit under 4 cms.

Asessippi Provincial Park is established around the southern arm of the lake.

Specifications

The dam is 70 feet (21 m) high and 4,200 feet (1,300 m) long.[2]

The reservoir is 35 miles (56 km) in length and stores 390,000 acre feet (480 million cubic metres) at the spillway crest level of 1,408.5 feet (429.3 m). Outflows are controlled by a gated conduit and a 210-foot (64 m) wide concrete chute spillway. The normal summer level target is between 1,400 feet (430 m) and 1,404 feet (428 m).[2]

Fish species

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.

Gallery

• 
  Shellmouth Dam sign
• 
  Lake of the Prairies from the Shellmouth Dam
• 
  Shellmouth Dam Control Structure
• 
  Shellmouth Dam Spillway

See also

• List of lakes of Saskatchewan
• Portage Diversion (Assiniboine River Floodway)
• Red River Floodway

References

External links

• Lake of the Prairies Conservation District
• Fish Species of Saskatchewan
• Lake Levels