April 1, 2010
Flood Bulletin #3
A Colorado low in the U.S. is expected to move further north than previously expected. This will bring significant rainfall over the Red River Valley from Grand Forks to Lake Winnipeg. Environment Canada expects rainfall amounts from tonight to Saturday morning to range from 20 to 30 millimetres (0.8 to 1.2 inches) with a possibility of 35 mm (1.4 in.) in some areas. While the rain won’t be of high intensity, it is falling on wet soil and, therefore, significant run-off is expected.
Flood Forecast
· As a result of this anticipated rainstorm, Red River crest levels have been adjusted by Manitoba Water Stewardship. The increase in the anticipated crests ranges from 6.1 centimetres (1.2 inches) at Emerson, 0.18 metres (0.6 ft.) at Morris, 0.3 m (one ft.) at Ste. Agathe, 0.5 m (1.5 ft.) at St. Adolphe and 0.6 m (two ft.) at the floodway inlet. While these increases are relatively small in some areas, they may have a significant impact on flooding and transportation. Crests will still be lower than those of 2006. Forecasts will be further updated this weekend if rainfall and run-off change significantly from what is currently expected.
· The crest will be a little later due to the rain and is expected at Emerson April 2 to 3, Morris April 7 and St. Adolphe April 9. Minor rises are expected from Selkirk to Breezy Point with a small crest late next week.
· Red River rises during the 24-hour period ending at 9 a.m. this morning were three cm (1.2 in.) at Letellier, 0.15 m (0.5 ft.) at Morris and St. Adolphe, 0.13 m (0.44 ft.) at the floodway inlet and 7.1 cm (2.8 in.) in downtown Winnipeg. The level at Selkirk declined about three cm (1.2 in.).
· The river level in downtown Winnipeg stood at 5.6 m (18.24 ft.) at 9 a.m. this morning. The level is expected to range between 5.5 and 5.8 m (18 and 19 ft.) from now until about April 14. A peak of 5.9 m (19.5 ft.) could occur due to an ice run on the Assiniboine River, which could occur this weekend or early next week.
Assiniboine, Souris, Pembina Rivers
· The Portage Diversion which diverts water from the Assiniboine River to Lake Manitoba began operating just after 11 a.m. today. The operation is being undertaken to reduce river levels in the city of Winnipeg and to prevent ice jamming on the Assiniboine River where ice has not yet moved in many areas including in the city. Lowering river levels in the city will reduce the risk of sewer backup should an intense rainstorm develop over the city over the next few weeks.
· Assiniboine River flows and levels have risen slowly in recent days due to the unusually mild weather which has melted some remaining snow and allowed water to break through minor snow blockages in drains and ditches. Relatively minor crests, well within the river’s bank, are expected next week. Crests from Baie St. Paul to west Winnipeg will likely occur during the next two to three days due to the Portage Diversion operation.
· The Shellmouth Reservoir water level was 424.86 m (1,393.89 ft.) this morning and is expected to rise to 425.7 m (1,396.5 ft.) by mid-April even with dry weather. With at least normal rainfall during April and May, the reservoir could rise to within a few feet of the summer target level of 427.5 m (1,402.5 ft.) by early summer.
· Levels of the Souris River and the Pembina River have risen slowly during the past few days but remain well below averages for the spring run-off period. Rock Lake rose to 406 m (1,332.2 ft.) this morning and is expected to crest near 406.8 m (1,334.5 ft.) early next week. The crest last spring was 408.25 (1,339.4 ft.).
· Minor flooding of hay fields along the Souris River near Coulter will continue for a few more weeks.
Flood Response Activity
· Manitoba Infrastructure and Transportation is monitoring the situation and assessing PTH 75 on an ongoing basis. Based on the current flood forecast, PTH 75 could be closed as early as Saturday, April 3 for up to about 10 days.
· PR 200 will also be assessed on an ongoing basis.
· The ring dike at St. Jean Baptiste is partially closed on the east side of town. The ring dike at Emerson is partially closed in two locations. Other community ring dikes in the Red River Valley are being assessed on a daily basis.
· Detours will be marked and the public is encouraged to check on road conditions. For the most current information on highways, call 1-877-MBROADS (1-877-627-6237) or check www.gov.mb.ca/mit/roadinfo or www.manitoba.ca.
· The Flood Liaison Office is open at 204-945-2121. It provides flood-level information related to properties in the Red River Valley.
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