Lake Diefenbaker Updates
Lake Diefenbaker Updates
Updated August 20, 2026
Current Conditions
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Headwater flows are generally receding. Flows in the Oldman and Red Deer River basins are generally between lower quartile and median levels, while flows in the Bow River Basin are generally between median and upper quartile levels.
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Receding headwater flows and increasing diversions in Alberta are expected to contribute to declining inflows into Lake Diefenbaker.
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Inflows into Lake Diefenbaker are currently near the upper quartile for this time of year. Inflows are forecast to move closer to the seasonal median by the end of the forecast period.
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Lake Diefenbaker water levels are currently within the historical interquartile range but below the seasonal median.
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Conditions will continue to be monitored closely, and outflows may be adjusted as needed based on updated forecasts and observed basin conditions.
Forecast Overview
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Inflows into Lake Diefenbaker will likely peak today, August 20, before gradually declining from approximately 230 m³/s on August 21 to 115 m³/s by August 30.
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Daily mean outflows are expected to remain relatively steady between approximately 180 m³/s and 200 m³/s over the forecast period.
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Lake Diefenbaker levels are expected to remain near 555.51 m for the first few days before gradually declining to approximately 555.40 m by the end of the forecast period.
Note: Flows shown in the table above are mean (average) daily flows. Actual releases from Lake Diefenbaker may fluctuate throughout the day as SaskPower adjusts operations at Coteau Creek Hydro Station to meet the Province’s electricity demands.
Hydrologic / Weather Conditions
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Minimal precipitation was received across the South Saskatchewan River Basin headwaters this week.
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No significant precipitation is forecast for the weekend. As a result, rainfall is not expected to provide a significant increase in headwater flows in the near term.
Below are the updated plots showing 2026 observed inflows and reservoir elevations compared to historical ranges.
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