Lower Assiniboine River, from Portage La Prairie to Headingley

FLOOD REPORT FOR MANITOBA

April 18, 2017 – 9:00 am

Flood Watch*: - Lower Assiniboine River, from Portage la Prairie to Headingley

Flood Warning*: - Upper Assiniboine River, between the Shellmouth Dam and Holland - Pelican Lake - Carrot River, due to high flows and potential for ice jamming on the Carrot River and on the Saskatchewan River downstream of the confluence

Summary  There are no wind alerts. Winds have diminished and are forecasted to be moderate for the next two days.

 A Flood Warning remains issued for the Carrot River as ice jamming is occurring, flows on the river are high and the downstream Saskatchewan River water levels are high due to the presence of ice. Current flows on the Carrot River at Turnberry, Saskatchewan are declining slightly. Flows on the Carrot River at Turnberry are at 5,600 cfs (159 cms). The peak flow on the Carrot River has reached The Pas, and is expected to remain relatively constant over the next week. Water levels will be impacted by ice jamming.

 Discharge to the Lower Assiniboine is being incrementally reduced. Beginning today, the flow on the river will be decreased at a rate of approximately 250 cfs (7.1 cms) per day until the flow on the river reaches 10,000 cfs (284 cms). Flows will be decreased 13,500 cfs (382 cms) this morning. This rate of decrease is contingent upon favourable weather conditions.

 All flow and water level information is based on data available at 7:00 am. Flood sheets with updated information will be posted later today at https://www.gov.mb.ca/mit/floodinfo/floodoutlook/forecasts_reports.html.

 Any questions or concerns about flood mitigation should be directed first to the municipal authority. Questions about water levels, provincial waterways, or provincial water control infrastructure can be directed to 204-945-3819, from 8:00 to 16:00 daily.

Weather  Trace amounts of precipitation were reported at most locations in Manitoba yesterday; however, locations south of the border received greater amounts of precipitation. Fargo reported 15.4 mm of rain and Grand Forks reported 13.4 mm of rain.

 Temperatures will remain cooler today with overnight lows below zero for the next two days. Overnight temperatures will begin to increase on Thursday.

 Minimal precipitation is in the short term forecast. A five day long range forecast predicts 25 – 40 mm of precipitation for the upper Assiniboine River basin in Saskatchewan.

 Winds have diminished and are expected to be moderate in Manitoba for the next two days (16 to 24 km/hour). Winds are from the north/northeast today, changing to east tomorrow and south/southeast on Thursday.

Red River Basin  The Red River and most of its tributaries continue to decline. The Red River upstream of the Floodway Inlet crested on April 4 at 760.35 feet and is currently at 752.3 feet.

 The Red River Floodway continues operating under Rule 1 to lower water levels in Winnipeg while keeping water levels at or slightly below natural upstream of the inlet control structure. Flow in the Floodway channel is 3,192 cfs (90 cms). Flows upstream of the Floodway Inlet on Tuesday morning are approximately 33,100 cfs (937 cms).

 With the Floodway in operation and flows on the Red River receding, water levels at James Avenue have dropped below 17 feet, currently at 16.5 feet. Flow at James Avenue on Tuesday morning is 45,641 cfs (1,293 cms).

 At the current rate of decline in Red River flows it is expected that Floodway operations will end within the next 7 days.

Pembina River Basin  A Flood Warning remains in effect for Pelican Lake. Water levels on Pelican Lake are above the flood stage of 1354 feet. The current lake level is near crest at 1,354.1 feet and the lake outflow is currently at maximum discharge. Water levels are expected to remain high on the lake for some time.

Assiniboine River Basin  A Flood Warning remains issued for the Upper Assiniboine River, between the Shellmouth Dam and Holland as flows from the Shellmouth Dam are maintained.

 A Flood Watch remains in effect for the area between Portage la Prairie and Headingley. Flow on the Assiniboine River downstream of the diversion is 13,600 cfs (385 cms).

 The Shellmouth Reservoir water level is at 1,396 feet. Current inflows to the reservoir are approximately 4,100 cfs (116 cms). Outflows from the dam are 3,800 cfs (108 cms). Inflows to the reservoir are declining.

 Water levels in Manitoba continue to decline at Russell, St. Lazare, Griswold, Brandon, Holland and upstream of the Portage Diversion Reservoir. Flows upstream of the Portage Diversion channel are 31,500 cfs (892 cms) and continue to decline.

 As of this morning, flow on the Portage Diversion channel is 17,900 cfs (507 cms) and flow on the Assiniboine River downstream of the diversion is 13,600 cfs (385 cms).

 Work is being done to restore the failsafe section of the Portage Diversion as flows on the Portage Diversion recede.

 The objectives of this operation are: o To provide relief to the communities between Portage La Prairie and Headingley while reducing flow on the Lower Assiniboine River at a rate that does not compromise dike and riverbank stability.

Souris River Basin  Flows on the Souris River are high and are expected to remain high for some time as they are declining slowly. Flow at Wawanesa is 11,400 cfs (323 cms) this morning.

 Flows on the Plum Creek at Souris are 1,270 cfs (36 cms) and continue to have minor increases.

Parkland Region  Most major tributary flows in the southern Parkland are declining.

The Pas and Northern Manitoba  Flows on the Red Deer River in Saskatchewan continue to decrease; however, the Red Deer River downstream of Red Deer Lake is increasing as the lake level rises. However, water levels on Red Deer Lake are within the normal operating range.

 A Flood Warning remains issued for the Carrot River as ice jamming is occurring, flows on the river are high and the downstream Saskatchewan River water levels are high due to the presence of ice. Current flows on the Carrot River at Turnberry, Saskatchewan are declining slightly. Flows on the Carrot River at Turnberry are at 5,600 cfs (159 cms). The peak flow on the Carrot River has reached The Pas and is expected to remain relatively constant over the next week.

 Water levels on the downstream part of the Carrot River within Manitoba are influenced by Carrot River flows and water levels on the Saskatchewan River where the two rivers meet.

 The Carrot River at Mile 22, Mile 9 and Bracken Dam are experiencing levels higher than 2011. Levels on the Carrot River in Manitoba have remained relatively stable over the last 12 hours.

 The Saskatchewan River at The Pas is at 61,000 cfs (1,728 cms). Flows increased by approximately 700 cfs (20 cms) over the last 24 hours and appear to be close to crest. Due to high flows and the strength and thickness of river ice, there is a threat of future ice jamming. Ice jamming normally occurs when flows are at approximately 50,000 cfs (1,416 cms). Ice jamming has not yet occurred on the Saskatchewan River at The Pas.

Manitoba Lakes  Generally, significant or full ice cover is reported on all major Manitoba lakes.

 The risk of shoreline ice pileup on Manitoba’s major lakes is low for today. Winds have diminished and are expected to be moderate over the next two days (16 to 24 km/hour).

 Today, the flow on the Waterhen River is 11,500 cfs (326 cms).

 The Fairford River Water Control Structure is being operated for maximum possible discharge; outflow from Lake Manitoba is approximately 11,400 cfs (323 cms).

 The Lake Manitoba water level this morning was at approximately 813.1 feet at the Steep Rock gauge. The median forecast is 813.85 feet for the end of May.

 The estimated natural outflow from Lake Manitoba at the current lake level, if the Fairford River Water Control Structure and associated channel improvements hadn’t been constructed, is approximately 3,200 cfs (91 cms).

 The Lake St. Martin water level this morning was at approximately 802.7 feet. The median forecast is 803.4 feet for the end of June.

 The median forecast represents average weather to predicted lake peaks.

 The Lake Winnipegosis water level this morning was at approximately 834.0 feet.

 The Lake Winnipeg water level this morning was at approximately 715.7 feet.

 The Dauphin Lake water level this morning was at approximately 857.5 feet. Ice pileup has increased in the vicinity of Dauphin and Ochre beach.

 The Nutimik Lake water level this morning was at approximately 904.0 feet.

*Definitions Flood Warning: A flood warning is issued when river or lake levels are exceeding or are expected to be exceeding flood stage within the next 24 hours.

Flood Watch: A flood watch is issued when river or lake levels are approaching and likely to reach flood stage, but likely not within the next 24 hours.

High Water Advisory: A high water advisory is issued when a heavy storm or high flows are expected and may cause water levels to rise, but not necessarily reach flood stage. A high water advisory can be an early indicator for conditions that may develop into a flood watch or flood warning.