News

The Water Security Agency (WSA) uses a balanced and proactive approach to manage water supplies from Lake Diefenbaker to meet the needs of all users, both on and downstream of the reservoir. Lake Diefenbaker supplies water to 60 per cent of Saskatchewan’s population including municipal, industrial, recreation, irrigation and hydroelectricity, as well as flood control.

With low mountain runoff projected this year, WSA has been using careful water retention and reservoir management to support ongoing system demands and to be prepared for another potentially dry summer. WSA will continue to monitor conditions closely and is prepared to reassess outflows if there is a significant change, such as a major rainfall event.

Current State of Reservoir 

• Currently Lake Diefenbaker is above normal for this time of year and is sufficient to meet the needs of communities for water supply, agricultural producers, industry and habitat for the year.
• However, the current inflow from Alberta into Lake Diefenbaker is about half what we normally see this time of year.
• Mountain snowpack is lower than normal and is expected to start melting in mid-to-late May, with most water flowing into the system in early to mid-June.
• Without significant rainfall during snowmelt, spring and summer inflows into Lake Diefenbaker will remain below normal.

Mountain Snowpack

• Approximately 99 per cent of the inflows on the South Saskatchewan River comes from Alberta, and 80 per cent of that is from the mountain snowpack.
• Dr. John Pomeroy, Director, USask Centre for Hydrology, indicates that inflows from Alberta snowpacks are down about 70 per cent from normal.

Current Operations and Outflows

• Various release scenarios were considered; all options resulted in impacts to the reservoir.
• WSA is maintaining planned outflows of 60 to 70 m3/s (similar to last year) as part of a balanced and responsible approach to water management.
• If conditions improve, WSA will adjust accordingly.

Potential Impact of High-Volume Releases

• High-volume releases would bring only short-term benefits in shifting sediment (sandbars) downstream of Lake Diefenbaker.
• Any additional water released from the dam would be temporary and would not keep the river higher throughout the spring and summer.
• A higher release could:
  • pose risks to municipal water intakes, fish and wildlife habitat, ferry operations, and recreational safety along the river;
  • cause additional erosion of the riverbanks upstream, adding silt to the river; and
  • trigger spills at Codette Reservoir and Tobin Lake, with downstream impacts in sensitive delta environments.

Potential Impact to Reservoir

• WSA has managed the reservoir in a way that will ensure enough water for all users of the reservoir. However, releasing a large amount of water like the amount requested by The Prairie Lily would lower the lake by approximately half a metre.
• Lowering the lake level this much could place significant strain on the reservoir, potentially jeopardizing the ability to meet essential water demands later in the summer and fall.
• Some scenarios would even require use of the spillway—an action normally reserved for flood operations.