Northern Saskatchewan Summer High Water Update – August 26, 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 June and July.
Over the past week, the southern portions of the Churchill River Basin and into the Saskchewan River Basin received 3 to 12 mm. The exception is the Paradise Hill area southwest of Meadow Lake where between 22 and 45 mm of rain was received this past week. The remainder of the Churchill River Basin generally received between 12 and 24 mm, with two exceptions. First, the area around Reindeer Lake received up to 30 mm. Secondly, the area in the west along the Alberta Border from La Loche up to Lake Athabasca, received rainfall amounts that ranged from 27 to 42 mm.
Flows and Lake Levels:
High river and lake levels can be expected for the remainder of summer and in some cases, such as the mainstem of the Churchill River, into the fall and winter. Many locations saw an increase in flows and levels in response to the rainfall that occurred over the past weekend (August 8-10), but have since stabilized or are declining. The expected peak or observed peak throughout the system is 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, have exceed previous historical highs.
Below are specific conditions at various locations as well as projected future peak levels:
Ile a la Crosse:
Present elevation: 421.07 m
Levels at Lac Ile a la Crosse saw a slight increase over the weekend due to the rainfall received but are beginning to decline once again. Levels will remain higher than normal for the remainder of the open water season and vulnerable to additional rainfall events and wind events.
Lac La Ronge:
Current elevation: 364.95 m
Observed peak: 364.97 m on August 22, 2020
While surface water inflows are declining levels on Lac La Ronge have been holding steady near 364.95 m. Even though inflows are receeding, they remain higher than normal and have been holding the lake level relatively steady over the past two weeks. Wind continues to cause fluctuations in the water levels. It is our expectation that declines in the lake level will be observed in the coming days unless additional rainfall is received over the basin.
Sandy Bay
Present Elevation: 9.43 m (2135 m3/s)
Observed peak: 10.15 m (2420 m3/s) on August 4 (wind affected)
Water levels at Sandy Bay reached a peak on August 4 and are now down about 0.7 m. Levels are now down below the 2005 peak. Flows and levels are expected to remain relatively steady for the next week.
Meeting Lake
With warm and dry conditions over the past week, water levels at Meeting Lake have been dropping. There has been minimal precipitation recorded in the area over the last two weeks.
Present elevation: 739.37 m – August 21, 2020
Observed peak: 739.48 m – July 27, 202
Meeting Lake has reached its outlet and is confirmed flowing into outlet channel. There is not significant flow moving through outlet currently as it is congested with thick vegetation. Berms around the lake are now built to WSA recommended height (739.83-740 m)
Cumberland House
Cumberland Lake has peaked and is receding. The lake is now down 1.47 m from the peak observed in late July. Forecasted levels for Cumberland Lake are part of WSA’s 10-Day Saskatchewan River Forecasts which can be found here: https://www.wsask.ca/Lakes-Rivers/Provincial/
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 appearing to be at its peak, Deschambault Lake has likely peaked and a peak at Amisk Lake can be expected prior to the end of the month or in early September. 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
Throughout today and into tomorrow Sandy Bay and Cumberland House areas are expected to receive between 15 and 30 mm. Through Thursday and into Friday, the far northwest corner over Lake Athabasca is expected to receive the 15 to 30 mm. The remainder of the north is expected to receive 3 to 15 mm throughout the week.
The greatest concern at this time is at Lac La Ronge, which is expected to receive about 15 mm of rain over the coming days, based on current forecasts. While the forecasted rain will slow the recession of high water across the north, it is not expected to result in any higher peaks than what has already been observed. The exception is likely to be Lac La Ronge where direct rainfall on the lake is expected to result in slightly higher levels.
For more information, contact:
Patrick Boyle
(306) 631-6997