Inflow to Lake of the Woods remains in the normal range and the lake level is expected to continue rising over the next week. As per the Regulation Strategy, under normal inflow conditions, the Board is targeting a summer level between 322.8 and 323.1 m (1059 to 1060 ft) with an outflow between 300 and 700 m3/s. Therefore, to balance lake levels and flows on the Winnipeg River, another small outflow increase is scheduled for tomorrow. This outflow increase is in line with the strategy, and will allow both the lake and river levels to gradually rise.
How does the level of Lake of the Woods compare to the levels on the Winnipeg River?
On July 28, the level of Lake of the Woods was 322.83 m (1059.1 ft), which is 20 cm (8 in) lower than the median level for the end of July. On the Winnipeg River, the level directly below the Norman Dam was 30 cm (12 in) lower than median, and the level at Nutimik Lake in Manitoba was 75 cm (30 in) lower than median.
How will the outflow increase affect levels of the lake and river?
This outflow increase will slow the rate of rise of Lake of the Woods by 0.4 cm (0.15 in) over the next 7 days.
The level of the Winnipeg River will increase by 5 cm (2 in) below the Norman Dam, 3.5 cm (1.4 in) above Kimberley Rapids and 2 cm (0.8 in) at the Dalles as a result of this flow change. Levels at Minaki will not be affected.
How much inflow is needed for levels on Lake of the Woods to rise?
Lake of the Woods will rise by approximately 1 cm (0.4 in) over the course of a week for every 64 m³/s of excess inflow —that is, if inflow exceeds outflow by that amount.
For example, on July 28, the 7-day average inflow to the lake was 460 m³/s, while the outflow was 275 m³/s, resulting in an excess inflow of 185 m³/s. Since 64 m³/s results in a 1 cm rise, an excess of 185 m³/s would lead to a rise of about 3 cm (1.2 in) over the week.
The current level of Lake of the Woods is 322.83 m (1059.1 ft), a 15th percentile level, below the normal range for this time of year. The average lake level increased by 3.3 cm (1.3 in) over the last week and is expected to increase by up to 2 cm (0.8 in) over the next week. Lake of the Woods authorized outflow will increase from 275 to to 300 m3/s tomorrow, Wednesday July 30.