As drought conditions persist across the Winnipeg River basin, the Lake of the Woods Control Board (LWCB) is planning ahead for its upcoming October Regulation Meeting and setting targets for winter flows and end-of-winter levels. The LWCB has been reviewing long term forecasts and metrological indicators. The National Oceanic and Atmospheric Administration (NOAA) has issued an El Niño advisory, indicating it is very likely El Niño conditions will persist through the winter and that they may develop into a strong event.
You may have heard the term El Niño before. El Niño and La Niña describe the warming and cooling trends of climate patterns that develop over the Pacific Ocean. When ocean temperatures warm (El Niño) or cool (La Niña) they impact wind and rainfall patterns all over the globe, including North America. Generally, El Nino conditions cause warm and dry conditions in the Winnipeg River basin, and La Nina conditions cause cool and wet conditions. Studies have shown that El Niño and La Niña conditions can increase the risk of droughts and floods, respectively.
This winter, under El Niño conditions, the Winnipeg River basin can expect the predominant storm track to be further south, resulting in a milder winter with potentially lower than normal snowfall. With less snowfall over the winter, there in an increased chance for lower than normal spring flows. Thus, if El Niño conditions persist or strengthen over the winter and into next year, there is a chance drought conditions in the Winnipeg River basin may also persist.
Typical El Niño Winters, Graphic produced by NOAA, Published July 2021
In light of these developing conditions, the LWCB will temporarily decrease Lake of the Woods outflow to 100 m3/s on Friday, September 15. This outflow reduction is expected to last until mid-October.
By reducing outflow now, while inflow to the lake is at its lowest, some additional water will be stored in the lake. This extra storage will help maintain slightly higher lake levels over the course of the winter and ensure March lake levels are higher than those experienced under extreme drought conditions. To be clear, March lake levels are still expected to be lower than normal, however in case of extended drought conditions next year, having that little bit of extra storage may help provide sustained flows on the Winnipeg River.
This outflow reduction will cause levels on the Winnipeg River to decrease by approximately 8 cm (2 in) downstream of the Norman Dam, 3 cm (1 in) at the Dalles and will cause very little level change at Minaki.
If you have any concerns or questions about this outflow reduction, or drought conditions in the basin, please contact Secretariat staff by emailing us at secretariat@lwcb.ca or calling our toll free number at 1-800-661-5922.