Northern Saskatchewan Summer High Water Update – September 29, 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 fell in the months of May, June, and July, where accumulations at some sites exceeded 200% of normal.
Over this past week, most of the Churchill River Basin received 9 to 20 mm, with the heaviest rain occurring in the northeast in the Hatchet Lake area. Father north, over Lake Athabasca and in the Stony Rapids area, 27 to 45 mm of precipitation was received. These amounts are not expected to result in any higher peak flows or levels than what has already been observed.
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: 420.97m
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: 364.84 m
Observed Peak: 364.95 m (August 10-30)
Over the past week, 9 mm of rainfall has been recorded at La Ronge and lesser amounts over headwater areas near Montreal Lake, and lake levels continue to decline. Lac La Ronge is still expected to go into winter at a level similar to what was experienced in 2011.
Sandy Bay
Present Elevation: 8.56 m (1830 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 1.6 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 drop below 1800 m3/s by the end of the month and continue to slowly recede in October.
Meeting Lake
With warm and dry conditions over the past month, levels at Meeting Lake have been dropping. 25 mm of precipitation has been recorded since September 1.
Present elevation: 739.27 m – September 18, 2020
Observed peak: 739.48 m – July 27, 2020
Future Rainfall
Minimal precipitation is expected to fall over the next couple of days, with only 1 to 10 mm of precipitation expected across most of the north. A small precipitation event is expected to occur early next week, with the northeast corner of the province forecasted to receive an additional 15 mm.
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 fell in the months of May, June, and July, where accumulations at some sites exceeded 200% of normal.
For more information, contact
Patrick Boyle
(306) 631-6997