Flood Conditions Update for Manitoba

September 01, 2010

The flood warning is continued for the Assiniboine River downstream of the Shellmouth Dam.

Weather and Effect on Rivers and Lakes:

  • In the last 24 hours, unstable weather has produced up to between 20 and 50 mm over portions of the Saskatchewan/Manitoba border, and in Southern and Central Manitoba.
  • Heavier rainfall occurred in the north-central and north-eastern Manitoba, where amounts were:- Gillam: 43 mm, Norway House: 41 mm Grand Rapids: 50 mm. However, no significant flooding has been reported by this morning from those areas. Other significant rainfall amounts were reported as:- Winnipeg: 31 mm, Berens River: 31 mm, and Kamsack: 21 mm.
  • Additional rainfall in Winnipeg City and the surrounding area has caused the Red River at James Avenue to rise by nearly one and a half feet due to localized overland flooding in the last 48 hours. The Red River was 9.09 ft at James Avenue this morning.The Lockport dam was operated this morning to reduce water levels at the City of Winnipeg to acceptable level. At the time of this reporting the water level was dropping and stood at 9.04 feet.
  • Reports from Morris area indicate that flooded areas are receding significantly as of this morning.
  • Many streams in southern and central Manitoba, including the Assiniboine and Red River tributaries have either crested or close cresting.River flows are well within their banks.
  • In the Interlake region, the Fisher River, Icelandic River and Blood Vein River are close to their crests and within their river banks.
  • Lake levels have remained high with little change or slight decline.
  • The forecast calls for a chance of showers later today and tomorrow and a return to sunny and drier weather conditions on Friday for southern and central Manitoba. The rainfall amounts are not expected to exceed 15 mm.

Assiniboine River and Shellmouth Reservoir Operation:

The Shellmouth Reservoir level has risen by 0.06 ft in the last 24 hours and stoodat 1410.46 ft this morning. The conduit was shut off yesterday morning. The spillway flow is 1740 cfs. The computed inflow is 2500 cfs. The conduit will remain closed until the reservoir outflow declines to 1600 cfs.

The Assiniboine River level immediately downstream of the reservoir is still slightly above bankfull level. Upstream of the Shellmouth Reservoir, the Shell River and the Assiniboine River at Kamsack have risen by 0.5 and 0.1 feet since yesterday but are expected to crest in the next two to three days.

Lakes Conditions:

  • Lake Manitoba Levels crested during the period of July 5-15 to a wind eliminated level of about 812.55 feet. Levels are continuing to recede and/or fluctuate due to winds and higher inflows.
  • Lake Winnipeg levels jumped to a higher crest level of about 715.6 feet during the stormy and gusty period of August 14-26. Since then, the lake level has remained generally unchanged.
  • Lake St. Martin wind eliminated level crested to about 801.4 feet during July 19-22 period and is fairly steady and under the top of its flood stage of 801.7 feet this year.
  • Lake Winnipegosis has stayed at a crest wind eliminated level of about 832.68 feet since August 20.
  • Dauphin Lake has crested at a level of about 857.94 feet during July 15-20 and levels are now continuing to recede.

Graphical information on lakes levels is updated regularly and posted at:

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