Recent precipitation has been well above normal across the Winnipeg River watershed. However, due to cold temperatures most of this has been snowfall and there has only been a gradual increase in stream flows in some areas. With temperatures rising and rainfall forecast through the weekend, the LWCB expects basin flow conditions to rapidly change over the next week, leading to quickly rising water levels in many areas. Due to the potential for rapidly changing flow conditions and unstable ice cover, extra caution should be taken when on or near water bodies across the region.
This rain on snow is expected to cause inflow to Lake of the Woods to rise to an extremely high rate, with the latest lake level forecasts showing between 15-30 cm of lake level rise over the next week. Because the lake was drawn down over the winter to create storage room for the spring melt, a 30 cm water level rise will not result in a high lake level. However, such a rapid filling of the lake would leave limited buffer room for wet conditions later in the spring when the region typically sees the wettest weather of the year.
In response, the LWCB is directing larger outflow increases from Lake of the Woods this week and next. The level of the Winnipeg River will rise quickly due to these outflow increases together with local runoff from rain and melting snow. By next week, the Winnipeg River level is expected to be at a high level for the end of April, comparable to a moderately high June level. The higher outflow will help to conserve storage room in the lake, reducing the risk of high levels on Lake of the Woods and along the Winnipeg River should wet conditions continue.
The current level of Lake of the Woods is 322.58 m (1058.3 ft), a 50th percentile level for this time of year. The average lake level rose by 9 cm (4 in) over the past week and is expected to increase by 15-30 cm (6-12 in) over the next week with the rapid rise in inflow.
Lake of the Woods authorized outflow is scheduled to be increased from 575 m³/s to 650 m³/s on Friday, April 22 and from 650 m³/s to 725 m³/s on Monday, April 25. Each of these outflow increases is expected to raise the level of the Winnipeg River as follows:
- Below Norman Dam: 18 cm (7 in)
- Above Kimberley Rapids: 18 cm (7 in)
- Winnipeg River Marina: 15 cm (6 in)
- Near Locke Bay: 15 cm (6 in)
- Above Myrtle Rapids: 15 cm (6 in)
- Above the Dalles: 14 cm (5.5 in)
- Above Throat Rapids: 14 cm (5.5 in)
- Minaki: no change from the first flow increase, 2 cm (1 in) from the second
Additional short-term river level rise is expected due to local runoff from rainfall and snowmelt.
Further outflow increases are likely next week. Details for these outflow changes will be provided on this Notice Board.
The current level of Lac Seul is 354.81m (1164.1 ft), a 45th percentile level for this time of year. The average lake level rose by 6 cm (2 in) over the past week and is expected to increase by 15-25 cm (6-10 in) over the next week.
Lac Seul authorized outflow is scheduled to be increased from 100 m³/s to 150 m³/s on Friday, April 22.