SASKATCHEWAN

Water Security Agency
April 24, 2023

Spring Runoff Update – April 24, 2023

The Water Security Agency (WSA) is providing an update to the spring runoff following significant snowfall in many parts of the province last week.

Province

The recent snowfalls will add to stream flows but because of cooler temperatures forecast for the next several days, runoff will generally be limited. Previous thawing of soils earlier in April will further help snow melt to infiltrate and soak into the ground contributing to a muted runoff from last week’s snowfall. At this time, WSA does not expect to see the recent snowfall causing any flooding as it melts.

Southeast

The near continuous snow resulted in lower temperatures and a slow melt of the recent snow. Observations at the Weyburn weather station show that snow depth has dropped from 15 cm on Thursday of last week to 8 cm today. Thus far, there has been no significant streamflow response from this melt. The expectation is that the bulk of the moisture from this snow will infiltrate with minimal streamflow response.  

Qu’Appelle

The Qu’Appelle lakes are continuing to rise, other than Crooked Lake, which is at its peak; however, peaks are expected to be within the range included in the April 18th update and likely at the lower end of the ranges as the recent snow isn’t expected to have an impact on these peak levels.

Levels on Pasqua, Echo, Mission, Katepwa, Crooked and Round lakes are expected to be similar to the peaks observed in spring 2022. No flood damages are expected.

Last Mountain Lake will see a peak higher than 2022, but no flood damages are expected.

Southwest

Flows are generally receding, and reservoir outflows have been staged down. While some snow remains at higher elevations in the Cypress Hills, we do not expect issues related to high flows as the last of the snow melts this week.

Central Saskatchewan

Flows are generally in-channel and receding with no issues reported at this time.

On the North Saskatchewan River, ice has cleared from most areas above Prince Albert (PA) and is expected to clear from areas below PA today or tomorrow. The river is high at PA but contained within its banks and is about 0.63 m lower than the peak levels observed during the 2019 ice breakup event.

There are no reports of any issues related to the ongoing ice breakup on the North Saskatchewan River at this time.

Lake Diefenbaker

With above normal snowmelt from prairie portions of the basin, Lake Diefenbaker levels rose about 1.3 m thus far in April, bringing it up to 552.71 m. In 2022, we didn’t reach this level until June 26 and were 1.55 m lower on April 24. The current level is also above our irrigation and recreation desired minimums. The current level is about 0.2 m above the historical median for this time of year, but remains at a safe level given the lower than normal alpine snowpack.

Once ice cover on the North Saskatchewan River breaks up and clears, outflows from Lake Diefenbaker will be increased from the current 60 m3/s to 90 m3/s. The plan is to be near 553.1 to 553.2 m at Lake Diefenbaker for June 1.

Weather Outlook

More precipitation is in the forecast mid-week with heaviest accumulations in the north, near Lac La Ronge, where 25-30 mm of mixed precipitation is expected.

Winds also look to be light this week, which will help reduce the risk for potential ice shoving in the southern lakes.

WSA advises that during runoff conditions flows can change rapidly and urges the public to always be caution along waterways and keep clear of ice jams if they occur.

WSA will continue to monitor conditions and provide updates as they develop.

For further information, please contact:

Patrick Boyle
Water Security Agency
Moose Jaw
Phone: 306.631.6997
Email: patrick.boyle@wsask.ca