Although the basin received less precipitation over the last week, inflow to Lake of the Woods remains high, between 1,400 and 1,600 m3/s, at 85th percentile for this time of year. As a result, the lake level has increased sharply, coming up 17 cm (7 in) over the last week. The current lake level of 322.95 m (1059.55 ft) is 5 cm ( 2 in) below the normal summer level of 323.0 m (1059.7 ft) and 117 cm (46 in) below the peak level in 2022 of 324.12 m (1063.39 ft).
The basins upstream of Lake of the Woods are slow to drain and outflow from Rainy Lake has been increased over the last few days. There is a significant rainfall event forecasted for June 3rd which could deliver up to 40 mm (1.5 in) of rainfall across a large portion of the Winnipeg River basin and directly over parts of Lake of the Woods. This rainfall, in addition to the high outflows from Rainy Lake, will sustain high inflows to Lake of the Woods over the next week. To manage lake level rise and avoid having the lake fill up too quickly, additional outflow increases are required as outlined below.
The current level of Lake of the Woods is 322.95 m (1059.55 ft), a 55th percentile level, within the normal range for this time of year. The average lake level increased by 17 cm (7 in) over the last week and is expected to increase by 10 to 18 cm (4 to 7 in) over the next week, depending on precipitation amounts and upstream flow changes. Lake of the Woods authorized outflow will increase to:
- 650 m3/s today, Friday May 31st
- 750 m3/s on Monday June 3rd
- 800 m3/s on Wednesday June 5th.
These flow changes will cause significant level increases downstream on the Winnipeg River. By Thursday June 6th, water levels will have increased by approximately 58 cm (23 in) directly downstream of the Norman Dam and by 38 cm (15 in) above the Dalles. Because Lake of the Woods outflow will surpass 700 m3/s, the water level at Minaki will start to rise and will increase by 18 cm (7 in) over the next week.
The current level of Lac Seul is 355.58 m (1166.6 ft), a 45th percentile level, within the normal range for this time of year. The average lake level increased by 28 cm (11 in) over the past week and is expected to increase by 14 to 20 cm (5.5 to 8 in) over the next week. Lac Seul authorized outflow is 300 m3/s with no additional outflow increases currently planned.
If you have any questions, comments or observations, please contact the Secretariat at secretariat@lwcb.ca or by calling 1-800-661-5922. This Noticeboard will be updated regularly as conditions develop.
For more information on Namakan and Rainy Lakes, visit the Water Level Notices page of the International Rainy-Lake of the Woods Watershed Board.