May 2025

The forecast for the Winnipeg River basin is extremely dry for the remainder of May, with no measurable precipitation expected in the next 7 to 10 days. To maintain stable water levels on Lake of the Woods, outflow reductions are required. With active spawning and increased recreation and boating on the Winnipeg River at this time of year, small and staggered outflow reductions will be made to allow for a gradual drop in river levels. Further north in the English River basin, flows are also starting to decline, but Lac Seul will continue refilling over the next week.

The current level of Lake of the Woods is 322.90 m (1059.4 ft), a 65^th percentile level, in the normal range for this time of year. The average lake level increased by 1.5 cm (0.6 in) over the last week and is expected to decrease by up to 1.0 cm (0.4 in) over the next week. Lake of the Woods authorized outflow will be reduced to:

• 575 m³/s on Friday, May 23^rd
• 550 m³/s on Monday, May 26^th
• 525 m³/s on Wednesday, May 28^th
• 500 m³/s on Friday, May 30^th

Each of these outflow reductions will cause levels along the Winnipeg River to decline. By May 30^th, river levels are expected to have decreased by 27 cm (10.6 in) below the Norman Dam, 21 cm (8.3 in) above Kimberley Rapids and 15 cm (6.0 in) at the Dalles. Levels at Minaki will not be affected by these flow changes.

The current level of Lac Seul is 355.37 m (1165.9 ft), a 55^th percentile level, in the normal range for this time of year. The lake level increased by 13.5 cm (5.3 in) over the last week and is expected to increase by 8.5 to 12 cm (3.3 to 4.7 in) over the next week. Lac Seul authorized outflow is 200 m³/s, with no changes scheduled.

The forecast for the next 7 to 10 days is extremely dry, with no rain expected for several days. With water supply to the major lakes declining, Rainy Lake outflow will be reduced this week and consequently, Lake of the Woods outflow reductions will also start tomorrow to maintain stable lake levels.

The current level of Lake of the Woods is 322.91 m (1059.4 ft), a 65^th percentile level, in the normal range for this time of year. The average lake level increased by 3.4 cm (1.3 in) over the last week and is expected to increase by 1.0 to 1.5 cm (0.4 to 0.6 in) over the next week. Lake of the Woods authorized outflow will be reduced to 600 m³/s on Wednesday, May 21^st and to 575 m³/s on Friday, May 23^rd.

Each of these outflow reductions will cause levels along the Winnipeg River to decline. By May 24^th, river levels are expected to have decreased by 21 cm (8.3 in) below the Norman Dam, 16 cm (6.3 in) above Kimberley Rapids and 12 cm (4.7 in) at the Dalles. Levels at Minaki will not be affected by these flow changes.

The current level of Lac Seul is 355.34 m (1165.8 ft), a 55^th percentile level, in the normal range for this time of year. The lake level increased by 14.8 cm (5.8 in) over the last week and is expected to increase by 11 cm (4.3 in) over the next week. Lac Seul authorized outflow is 200 m³/s, with no changes scheduled.

The extremely hot and dry conditions across the Winnipeg River basin this week have allowed for tributary flows to peak and lake level rise to slow on both Lake of the Woods and Lac Seul.

Forest fires have developed near several hydropower dams along the Winnipeg and English Rivers in Ontario and Manitoba, resulting in evacuation of these facilities. Manitoba Hydro has issued a media release related to its facilities at Pointe du Bois and Slave Falls. Ontario Power Generation’s Whitedog and Caribou generating stations have also been evacuated, but remote management of gates at these two facilities is available to adjust flow through the dams.

To provide for stable flows along the Winnipeg and English Rivers while these facilities are evacuated, the LWCB has temporarily paused changes in outflow from Lake of the Woods and Lac Seul dams for the next several days. The Secretariat is in regular contact with OPG and Manitoba Hydro and will reassess conditions over the weekend. 

The current level of Lake of the Woods is 322.89 m (1059.3 ft), a 70^th percentile level, in the normal range for this time of year. The average lake level increased by 6.7 cm (2.6 in) over the last week and is expected to increase by 2.5 to 6.5 cm (1 to 2.5 in) over the next week. Lake of the Woods authorized outflow is 650 m³/s, with no changes scheduled.

The current level of Lac Seul is 355.23 m (1165.4 ft), a 60^th percentile level, in the normal range for this time of year. The lake level increased by 15.7 cm (6.2 in) over the last week and is expected to increase by 15 to 18 cm (6 to 7 in) over the next week. Lac Seul authorized outflow is 200 m³/s, with no changes scheduled.

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The LWCB Basin Data page will not be updated on Monday, May 19^th (Victoria Day in Canada). Daily data updates and publication will resume on Tuesday, May 20^th.

Tributary flows and lake inflows are still high from the precipitation last week. However with dry conditions forecast for the weekend and into next week, flows are expected to peak in the coming days.

The current level of Lake of the Woods is 322.82 m (1059.1 ft), a 70^th percentile level, in the normal range for this time of year. The average lake level increased by 13.6 cm (5.4 in) over the last week and is expected to increase by 8 to 11 cm (3 to 4.3 in) over the next week. Lake of the Woods authorized outflow will increase to 600 m³/s today, May 8^th. There is a tentative outflow increase to 650 m³/s scheduled for Tuesday, May 13^th, to be confirmed on Monday.

As a result of these outflow increases, levels along the Winnipeg River are expected to increase by 28 cm (11 in) below the Norman Dam, 22 cm (8.6 in) above Kimberley Rapids and 16 cm (6.3 in) at the Dalles. Levels at Minaki will not be affected by these flow changes.

The current level of Lac Seul is 355.07 m (1164.9 ft), a 55^th percentile level, in the normal range for this time of year. The lake level increased by 17.6 cm (7 in) over the last week and is expected to increase by 13 to 14.5 cm (5 to 6 in) over the next week. Lac Seul authorized outflow is 200 m³/s, with no changes scheduled.

The Winnipeg River basin received above normal rainfall over the last week, with the highest amounts in the 50 to 75 mm (2 to 3 in) range over Lake of the Woods and the Rainy-Namakan basin (see map below). For comparison, average rainfall in the last quarter of April is 10 mm (0.4 in). Some additional bands of rain are forecast today and tomorrow, after which the remainder of the forecast shows warm and dry conditions through the first week of May.

Tributary flows and lake inflows have risen to the top of the normal range and in some locations are peaking well above normal, at 90^th percentile for this time of year. The LWCB is referring to its Regulation Strategy and using the guidelines for moderate inflow conditions to manage lake levels and flows. At Lake of the Woods, the lake level is rising quickly and will hit the preferred end-of-May level of 322.7 m (1058.7 ft) in the next few days. To slow lake level rise, the Board has scheduled staggered outflow increases over the next week, considering the need to balance rising levels downstream on the Winnipeg River. At Lac Seul, refill is on track to meet preferred mid-May lake levels for fisheries.

The current level of Lake of the Woods is 322.68 m (1058.6 ft), a 50^th percentile level, in the normal range for this time of year. The average lake level increased by 12.0 cm (4.7 in) over the last week and is expected to increase by 6 to 8 cm (2.4 to 3 in) over the next week. Lake of the Woods authorized outflow will increase as follows:

• to 500 m³/s on Thursday, May 1^st
• to 550 m³/s on Tuesday, May 6^th
• to 600 m³/s on Thursday, May 8^th

Each of these outflow increases will cause levels along the Winnipeg River to rise. By March 9^th, river levels are expected to have increased by 40 cm (15.7 in) below the Norman Dam, 30 cm (11.8 in) above Kimberley Rapids and 22 cm (8.7 in) at the Dalles. Levels at Minaki will not be affected by these flow changes.

The current level of Lac Seul is 354.89 m (1164.3 ft), a 45^th percentile level, in the normal range for this time of year. The lake level increased by 19.7 cm (7.8 in) over the last week and is expected to increase by 17 to 23 cm (6.7 to 9 in) over the next week. Lac Seul authorized outflow will increase to 200 m³/s on Thursday, May 1^st.