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2025.05.01 Level Forecast and Outflow Increases

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 90th 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 50th 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 1st
  • to 550 m3/s on Tuesday, May 6th
  • to 600 m3/s on Thursday, May 8th

Each of these outflow increases will cause levels along the Winnipeg River to rise. By March 9th, 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 45th 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 1st.