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2023.12.07 Level Forecast and Ice Formation Monitoring

The current level of Lake of the Woods is 322.66 m (1058.6 ft), a 30th percentile level for this time of year. The average lake level declined by 1.5 cm (0.5 in) over the past week and is expected to decline by up to 1.5 cm (0.5 in) over the next week. Lake of the Woods authorized outflow is increasing to 300 m3/s today, December 7.

This flow increase will cause levels on the Winnipeg River to rise by approximately 5 cm (2 in) downstream of the Norman Dam, 2 cm (1 in) at the Dalles and will cause very little level change at Minaki.

The current level of Lac Seul is 355.81 m (1167.3 ft), a 20th percentile level for this time of year. The lake level declined by 9 cm (3 in) over the past week and is expected to decrease by 7 cm (2.5 in) over the next week. Lac Seul authorized outflow is 325 m3/s with no changes scheduled at this time.

With the official start of winter a couple weeks away, the Lake of the Woods Secretariat has been monitoring the formation of ice on the major lakes and rivers in the Winnipeg River basin. We use observations from webcams or field visits to monitor ice formation. There is also a special tool on NASA’s Earth Observing Satellites, Terra and Aqua, that allows us to monitor ice over the entire Winnipeg River basin. The Moderate Resolution Imaging Spectroradiometer (MODIS) is a sensor on board both of these satellites that creates images of the earth’s surface. When skies are clear and there are no clouds blocking the view, the images of the Winnipeg River basin are extraordinary!

The image below on the left is from December 3d when there was a good view of Lake of the Woods. The image on the right is the same but shown in “false colour”, meaning different bands of the satellite signal were used to colour the image. In this image, ice and snow show up as a bright aqua blue colour, allowing us to see the ice forming over Lake of the Woods and all the other small lakes in the Winnipeg River basin.

Knowing when lakes and rivers have frozen over is useful for a variety of reasons. For example, to avoid damage to docks and ensure safe (and stable) ice conditions on the Winnipeg River, outflow increases from Lake of the Woods are kept at a minimum once a stable ice cover is in place. Ice also has an impact on water level and flow measurements. On lakes that are frozen over, the water surface no longer shifts due to wind setup and waves and becomes very smooth. This has happened at the gauges around Lake of the Woods in the last week and is evident in the Lake of the Woods level graph shown below. It can also be more difficult to estimate the flow of water under ice, and therefore the flow data for certain rivers may be less accurate and gets flagged in our data graphs by a pink line.