Spring Runoff Update – April 18, 2023
The Water Security Agency (WSA) is issuing the following updates for spring runoff conditions across the province.
WSA does not expect to see significant flood impacts at this time.
All peak levels are likely to be near or slightly higher (up to about 0.3 metres [m]) than those observed in spring 2022.
With a rapid snowmelt over much of the Qu’Appelle River Basin last week, many tributaries to the river observed peak flows that were a little higher than what had been expected when WSA issued its April Spring Runoff Forecast.
There is significant precipitation expected over much of the basin this week, with 15-25 centimetres (cm) of wet, heavy snow being forecasted. Snow is expected to accumulate but, with cooler temperatures expected late in the week, it is expected to melt slower with significant amounts soaking into the ground. A slower melt will reduce the amount contributing to streamflow and allow more water to soak into the ground and improve soil moisture conditions.
With the higher tributary flows and snow forecast, we are increasing the peak elevation expectations for the Qu’Appelle lakes. Peaks on the mainstem lakes, Pasqua, Echo, Mission, Katepwa, Crooked and Round, are expected late this week or early next. At this time, no significant impacts due to high water are expected, but ice may pose a risk if strong winds occur during ice break-up on the lakes resulting in ice shoves. Strong winds can push ice onto the shore and against structures causing property damage.
Last Mountain Lake is not expected to peak until late April or even early May if conditions are wet.
The control structures at Echo and Crooked lakes have all operable bays fully open and are not impacting upstream water levels. The control structure at Craven is also operating to help manage flows.
Buffalo Pound Lake is near peak at 510.1 m (0.65 m above typical summer levels). Water in Buffalo Pound Lake will be released into the system slowly to avoid any incremental downstream impacts as conditions allow.
The Moose Jaw River is at peak and expected to recede in the coming days. Observed flows were similar to 2022. Ice has cleared along the Moose Jaw River with only minor jamming.
Snowmelt is near complete over lower portions of Wascana Creek Basin but is still in the early stages above the City of Regina where an above normal runoff is expected. WSA will likely need to remove stoplogs from the Albert Street Weir on Wascana Lake.
Most of the Qu’Appelle River is now ice free, reducing the risk of ice jams and also increasing the river’s ability to move water downstream, reducing the risk of potential flooding.
Swift Current Creek
Flooding risk in Swift Current creek has tapered off since last week. While there is still runoff expected from higher up in the basin, the forecasted weather and precipitation is not anticipated to further increase the risk of flooding.
Flows at the City of Swift Current are down to 20 m3/s from the peak last week of 105 m3/s. Water levels at the city have dropped considerably and the risk of flooding is diminishing. Flows at the city are typically closer to 1-2 m3/s in late April.
Reid Lake is currently at 807.60 m (12 cm below full supply). Inflows to Reid Lake continued to drop over the past few days allowing for reductions in outflows at Duncairn Dam. This is also allowing Reid Lake to return to below its full supply level.
Outflows at Duncairn Dam have been reduced to 15 m3/s, down from a peak of 90 m3/s last week.
Old Wives Lake Basin
No communities are believed to be at risk at this time in the Old Wives Lake Basin, but Shamrock Regional Park may experience some localized flooding.
Inflows to Thomson Lake are dropping rapidly, allowing for a reduction in outflows and the reservoir returning below full supply.
A high flows advisory was issued for Notukeu Creek on Saturday. These flows continue to make their way down Notukeu Creek.
The risk of flooding on the Souris River below Rafferty, Boundary and Grand Devine dams is currently low and anticipated to remain low. There is, however, a risk of localized flooding related to the precipitation moving into the province today and continuing through Thursday.
Inflows to Boundary Reservoir have receded allowing for the diversion flow to be reduced.
Rafferty Reservoir is not expected to fill.
Grant Devine Lake may fill mid-week. WSA is monitoring conditions and is preparing operations to manage flows if needed.
Runoff is ongoing, but there are no issues or forecasted risk of flooding at this time. Overall, the runoff response appears to be progressing as outlined in WSA’s April 1 Spring Runoff Forecast.
Temperatures are expected to be much cooler through the week with mixed precipitation, rain transitioning to snow, expected from a Colorado Low moving into the province today.
Most of southern Saskatchewan is expected to see some precipitation with heaviest accumulations, likely in the southeast, where upwards of 50 mm is possible.
Snow is expected to have a high moisture content. While some snow is expected to melt on contact, accumulations are likely in the southeast.
Over areas where the snowmelt is largely completed, snow is better than rain as the moisture will be released slowly.
Areas within southeastern Saskatchewan, where the highest snowfall accumulations are expected, may see some localized flooding as this snow melts and enters watercourses. This includes Long Creek, Souris River, Moose Mountain Creek, Antler River, Pipestone Creek and lower portions of the Qu’Appelle River.
WSA reminds the public that flows along water bodies can change rapidly at this time of year and urges the public to take caution.
For More Information
In the event where a situation exceeds the coping capacities of the local authority or where the local authority requires extra support and/or resources, the Saskatchewan Public Safety Agency (SPSA) can provide additional assistance. SPSA can be reached by calling 1.800.667.9660, and further information on submitting a request for assistance can be found here.
WSA also advises that communities at risk of imminent flooding can access support with the Emergency Flood Damage Reduction Program (EFDRP). The EFDRP provides financial, engineering and technical support to evaluate the potential flood risk to buildings and to identify options to mitigate the risk when flooding is imminent. Services include client discussions, site visits, hydrological and other technical evaluations, developing mitigation recommendations and cost share funding for permanent flood defenses and temporary relief through pumping. For more information on EFDRP click here.
WSA will provide regular updates throughout the runoff period and as conditions change.
For further information, please contact:
Water Security Agency