Rainfall totals from last weekend’s Colorado Low were very high for this time of year, with the highest amounts around Rainy Lake. This is the sixth straight quarter-month period with well-above normal precipitation in the Rainy-Namakan and Lake of the Woods local sub-basins, making this April one of the wettest on record. With the most recent rainfall coming on snow and frozen ground, the rise in flows in tributaries across the region has been rapid.
The LWCB was informed that outflow from the Rainy Lake dam at Fort Frances-International Falls into the Rainy River is being maximized in response to the heavy rainfall in that area and rapidly rising Rainy Lake. Tributaries to the Rainy River, including the Big Fork River, Little Fork River, Rapid River, La Vallee River and Pinewood River are near to or have broken record high levels for April. The combination of very high flows out of Rainy Lake and from these tributaries has inflow to Lake of the Woods from the Rainy River at an extremely high rate. Additional runoff from around the lake is also contributing to a rapid rise in the lake level.
Most of the tributaries to Rainy River have either crested or appear to close to cresting for now, with several days of dry weather in the forecast. However, inflow to Lake of the Woods will remain very high and the lake will continue to rise quickly as a result.
The current level of Lake of the Woods is 322.77 m (1058.7 ft), a 70th percentile level for this time of year. The average lake level rose by 18 cm (7 in) over the past week and is projected rise 25-35 cm (10-14 in) over the next week. This projection is based on current 7-day precipitation forecasts and expected outflow adjustments from Rainy Lake. Higher rainfall totals or higher outflows could see greater rise in the lake level.
Lake of the Woods outflow was increased from 650 to 725 m³/s on Monday, April 25. Outflow is scheduled to be increased from 725 m³/s to 825 m³/s on Wednesday, April 27. The Winnipeg River is expected to rise as follows in response to this outflow increase, with additional rise possible from local runoff:
- Below Norman Dam : 30 cm (12 in)
- Above Kimberley Rapids : 24 cm (10 in)
- Winnipeg River Marina: 21 cm (8 in)
- Near Locke Bay: 21 cm (8 in)
- Above Myrtle Rapids: 21 cm (8 in)
- Above the Dalles: 20 cm (8 in)
- Above Throat Rapids: 21 cm (8 in)
- Minaki: 21 cm (8 in)
Further increases in outflow will follow in the coming days and will be posted on this Notice Board.
The current level of Lac Seul is 354.90 m (1164.4 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 rise by 2-7 cm (1-3 in) over the next week. Lac Seul authorized outflow is 150 m³/s. An outflow increase is being planned for Friday, April 29. Details will be provided on this Notice Board.