Northern Saskatchewan Summer High Water Update – July 27, 2020
Northern Saskatchewan Summer High Water Update – July 27, 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. In general, cumulative rainfall since April 1, 2020, is near record. As shown in the map below, rainfall accumulations over central and southern areas of the Churchill Basin has approach or exceeded 400 mm since April 1, which is about 200% of normal.
Rainfall over the past two days ranged from trace amounts to 62 mm near McLennan Lake.
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. In most areas flows and water levels are expected to peak, or have peaked, 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
Estimated peak: 421.1 m on or near July 28, 2020
Lac La Ronge:
La Ronge current elevation: 364.88 m
Projected peak: 364.98 m on or near August 23, 2020
While headwater areas in PA National Park received minimal precipitation over the weekend, higher accumulations were observed closer to Lac La Ronge with 37 mm at La Ronge. This is resulting in an increase in our forecasted peak and with an expectation that it will exceed levels observed in 2011.
Sandy Bay
Present Elevation: 9.98 m (2340 m3/s)
Forecasted peak: 10.22 m (2430 m3/s) on or near August 4
Declining inflows to Reindeer Lake have allowed SaskPower to bring Reindeer Lake down to 363.63 m, which is 5 cm below the Lake’s full supply level. The Reindeer Lake basin has also been drier than upstream portions of the Churchill River Basin allowing SaskPower to reduce outflows at the Whitesand Dam by 150 m3/s this week. However, with rains increasing flow forecasts for location on the Churchill River above Sandy Bay, the reduction in Whitesand Dam outflows will not have an impact on the peak forecasted for Sandy Bay.
Meeting Lake
- Spiritwood station received 14 mm of precipitation on July 25 (20 km N of Meeting Lake).
- Spiritwood has recorded 247 mm of Precipitation since April 1, 2020
- July 27, 2020, lake level is 739.48 m, which is unchanged from July 22.
- Outlet spill elevation is 739.23 m (25 cm lower than current lake level)
- 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 should now be built to WSA recommended standard (739.83-740 m)
- Local contractor is putting finishing touches on last berms currently (riprap, granular tops)
Cumberland House
Present Elevation: 267.77 as of 8:00 AM July 27, 2020
Forecasted peak: Peak observed on July 24, 2020
Jan, Amisk, and Deschambault Lakes
- These lakes are becoming an area of increasing concern with the significant rainfall over this area recently.
- Our current expectation is for 2017 levels to be surpassed and for levels to approach those observed in 1974.
Future Rainfall
There is minimal precipitation in the forecast for the upcoming week. Current model guidance has some precipitation over the far north, near the 60th parallel late in the work week, but, as currently forecasted, it would not impact areas that are currently experiencing high flows in the north.