Lake Diefenbaker Updates
Lake Diefenbaker Updates
Updated July 10, 2026
Current Conditions
- Most headwater stations are generally continuing to decline; however, flows are still much above median for this time of year.
- Inflows into Lake Diefenbaker peaked earlier this week and are now slowly dropping off. Flows are currently near upper decile levels for this time of year and are expected to continue declining throughout the weekend.
- Increasing irrigation demand in Alberta, particularly near the Bow River Basin, is also expected to contribute to reduced inflows into Lake Diefenbaker over the coming days.
- Water levels on Lake Diefenbaker are currently near upper quartile levels for this time of year and are expected to stay near upper quartile levels by mid-July with the high inflows.
- Releases from Coteau Creek Hydro Station are planned to remain near the current plant capacity of approximately 270 m³/s. The current spill is around 280 m³/s, resulting in a total release from Lake Diefenbaker of approximately 550 m³/s. It is planned to cut the spills to only 100 m³/s on Monday to get the total release to 370 m³/s.
- Conditions will continue to be monitored closely, and outflows may be adjusted as needed based on updated forecasts and observed basin response.
Forecast Overview
The table shows the updated 10-day forecast for Lake Diefenbaker.
- Inflows into Lake Diefenbaker continue to decline through the forecast period but will remain well above median for this time of the year.
- Total outflows are planned to remain around 550 m³/s over the weekend and will be reduced to 370 m³/s starting Monday morning. The flows will remain above median for this time of the year.
- Lake Diefenbaker levels are expected to rise to around 556.54 m.
Hydrologic / Weather Conditions
- This week, the South Saskatchewan River Basin headwaters received minimal rainfall.
- Over the weekend, minimal rainfall is forecast for the basin.
Below are the updated plots showing 2026 observed inflows and reservoir elevations compared to historical ranges.
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