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Northern Saskatchewan Summer High Water Update – September 15, 2020

Rainfall

Northern Saskatchewan has received extremely high cumulative precipitation since April 1, 2020, resulting in very high flows and lake levels across the Churchill River and Lower Saskatchewan River basins. Much of this rainfall has come in the months of May, June, and July, where accumulations at some sites have exceeded 200% of normal.

Most of the north received some showers over the past three days but accumulations have been less than 15 mm. Highest accumulations occurred west of Wollaston Lake. Accumulations over the Churchill River Basin were generally below 5 mm. 

Flows and Lake Levels

High river and lake levels can be expected for the remainder of fall and in some cases, such as the mainstem of the Churchill River, into the winter. The observed peaks throughout the system were generally slightly lower than previous historical highs. However, flows and levels in the Lower Churchill River, including Reindeer River and Churchill River near Sandy Bay, exceed previous historical highs. 

Below are specific conditions at various locations as well as projected future peak levels. 

Ile a la Crosse

Present elevation: 421.01 m

Levels at Lac Ile a la Crosse are continuing to decline; however, they will remain higher than normal for the remainder of the open water season and vulnerable to additional rainfall events and wind events. Based on historically similar years, levels prior to spring snowmelt in 2021 are expected to be 0.4-0.5 m higher than normal on Lac Ile a la Crosse.

Lac La Ronge

Current elevation: 364.90 m

Observed Peak: 364.95 m (August 10-30)

Over the past week, 7 mm or rainfall has been observed at La Ronge and accumulations ranging from 0.5 to 6 mm were observed over headwater near Montreal Lake. While this slowed inflow recessions some, the lake continued to decline. The expectation remains that Lac La Ronge will go into winter at a level similar to what was experienced in 2011.

Sandy Bay

Present Elevation:  8.81m (1910 m3/s)

Observed peak:    10.15 m (2420 m3/s) on August 4

Water levels at Sandy Bay reached a peak on August 4 and are now down about 1.35 m. Levels are now well below the 2005 peak. With flows upstream showing some slow declines, flows and levels at Sandy Bay will continue to decline slowly over the coming week. Flows are expected to be down below 1800 m3/s by the end of the month.

Meeting Lake

 With warm and dry conditions over the past month, levels at Meeting Lake have been dropping. Only 19 mm of rainfall was observed since August 1 at Spiritwood, the closest observations we have to Meeting Lake, with no significant rainfall events over the past three weeks.

Present elevation: 739.29 m – September 11, 2020

Observed peak: 739.48 m – July 27, 2020

Jan, Amisk, and Deschambault Lakes

 Jan Lake peaked in late July, 54 mm above 2017 levels. While we do not have any current information for Deschambault or Amisk lakes, with the Sturgeon Weir River at Leaf Rapids receding Deschambault Lake has likely peaked and a peak at Amisk Lake can be expected soon if it has not already occurred.  Like Jan Lake, peaks that are slightly above 2017 levels are expected at Deschambault and Amisk lakes, unless significant, additional precipitation is observed.

Future Rainfall

Some rain/snow showers are occurring in the extreme northeast today, bring a few milimeters of moisture to that area. Following that, there is minimal precipitation forecasted for northern Saskatchewan over the next five days.

 

For more information, contact

Patrick Boyle

(306) 631-6997

Patrick.Boyle@wsask.ca