Provincial Forecast

October 2025 Water Supply Conditions and Outlook Report

November 13, 2025

Please see the November 13, 2025 update below:

Lake Diefenbaker Forecast Overview:

• Inflows are expected to remain steady at around 90-100 m³/s.
• In preparation for the onset of freeze-up conditions within the next few weeks, the outflow from Lake Diefenbaker at Gardiner Dam will be increased to 120 m³/s on Monday November 17.
• Based on the forecasted inflows, the reservoir elevation is expected to decrease by 0.08 m over the next 10 days.

Current Conditions: 

• Inflows into Lake Diefenbaker are expected to remain steady in between the lower quartile and median levels for the rest of the week.
• The reservoir is at 555.06 m. This level is between the lower quartile and median for this time of year. Water levels are expected to decrease over the next week.
• The increase in outflows to 120 m³/s next week marks the beginning of the transition to winter operations at Lake Diefenbaker.

Hydrologic Conditions:

• No precipitation was received in the headwaters of the North and South Saskatchewan river basins over the past three days (Nov 10-12).
• Approximately 20mm of precipitation is anticipated along the eastern slopesthis weekend.