The Lake of the Woods Control Board (LWCB) says this has been the driest year for the Lake of the Woods sub-basin since 1961, according to its records.
According to Environment Canada's Historical Records, between January 1, 2021, and June 30, 2021, 152.8 mm of precipitation fell in the Kenora area.
The average rain/snowfall for this time period is 308.9 mm, meaning the Kenora area has only seen 49.46 per cent of the expected precipitation this year.
This coupled with a dry end of 2020 has led to river flows and water levels in all major lakes, both regulated and natural, across the Winnipeg River basin being well below normal for the early summer.
Matt DeWolfe, Executive Director at the LWCB, says the Control Board is looking at their operating strategy.
"We're certainly looking at operating strategy for Lac Suel and for Lake of the woods, preserving water, conserving it for the unknown future. We're coming out of the period of the year that normally we see the highest amount of precipitation, but it's very dry," said DeWolfe.
"Typically getting into late summer and the fall precipitation amounts aren't very high, so we're looking at a long horizon with the potential for reduced rainfall and continued dry conditions," DeWolfe added.
The level of Lake of the Woods sits at 322.63 metres, putting the lake in the 10th percentile for this time of year.
The level of Lake of the Woods has been declining since it hit its peak on June 11, 2021.
The LWCB lists three reasons for the declining level.
- Flows out of the Rainy-Namakan system, normally the main source of water for Lake of the Woods via Rainy River, have been at a minimum since June 8. This minimum rate is set by the International Joint Commission and is not subject to LWCB regulation.
- The dry, hot weather has resulted in very low flows coming out of other tributaries to Rainy River that feed Lake of the Woods.
- These conditions have also resulted in an uptick in evaporation directly from the lake. The combination of these factors has resulted in a rare occurrence – negative inflow to Lake of the Woods in early summer.
The LWCB says, "negative inflow occurs when the rate of water leaving the lake through evaporation is greater than the rate of all the water entering the lake (e.g., Rainy River flow, smaller tributary flows, rainfall directly on the lake). In years where it develops, it is typically in the late summer and early fall when water temperatures are higher and air temperatures have cooled, driving evaporation."
"The fact that negative inflows have developed so early in the summer is an indicator of the exceptionally dry conditions in the basin and is a cause for concern with respect to regulation of the lake for this summer and coming seasons," said the LWCB in a prepared release.
"With negative inflow, Lake of the Woods level has been declining gradually despite very low outflow from the dams in Kenora. The lake level is below navigational chart datum and care should be exercised when boating on the lake," continued the release from the LWCB.
The Lake of the Woods sub-basin is a part of the larger Winnipeg River basin, which is undergoing an unusual period of prolonged dry conditions.