Provincial Forecast
Please find below the July 10, 2025 update on Lake Diefenbaker conditions:
Hydrologic Conditions:
Over the past week, minimal precipitation was observed along the eastern slope areas. There is minimum precipitation projected in the headwater areas for the rest of this week.
Inflows:
Persistent hot and dry conditions in the headwaters of the South Saskatchewan River Basin have caused streamflows in upstream tributaries to steadily decline, while irrigation demand remains high across southern Alberta. As a result, inflows to Lake Diefenbaker continue to decrease and are currently below the lower quartile for this time of year. Inflows are expected to fall further and approach the lower decile (meaning in over 90% of the years of record flows have been higher than they are now) level by this weekend.
Outflow:
Current outflows from Lake Diefenbaker are approximately 65 m³/s. Given the inflow projections and current lake levels, daily average is expected to remain between 60–70 m³/s.
Lake Elevation:
The reservoir is currently at 553.53 m, which is below the median for this time of year. Water levels are expected to remain steady for the rest of this week and then start to recede next week. The water level is expected to remain below the lower quartile throughout the summer.
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