Northern Saskatchewan Summer High Water Update – July 24, 2020
Dam Integrity Update
Both the Water Security Agency (WSA) and SaskPower manage structures on the Churchill River and its tributaries, which are currently experiencing high flows.
SaskPower is committed to the safe operation of our infrastructure for both our staff and the public. We continue to perform regular inspections of all SaskPower owned dams, including increased frequency for those on the Churchill River system. We have not identified any structural issues or other dam safety concerns. Regular inspections will continue throughout the duration of this flood event. SaskPower will activate the appropriate emergency response plans in the event any concerns are identified.
The Water Security Agency operates the Lac La Ronge control structure and the forecasted peaks on the lake are expected to be below those experienced in 2011 and below the crest of the dam. WSA’s Dam Safety and major structures does not feel the structure is at risk of failure. Precautionary measures are being taken to ensure its safety including the addition of sandbags and increased inspections.
Conditions in the basin are being monitored for any changes.
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 over an area from Little Bear Lake over to Creighton has recorded more than 400 mm of rainfall since April 1.
Rainfall over the past three days generally ranged from 10-20 mm with higher amounts where thunderstorms occurred, such as near Trade Lake where accumulations of 40 mm were observed.
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: 421.06 m (potentially elevated by wind setup)
Estimated peak: 421.1 m on or near July 28, 2020
Lac La Ronge:
La Ronge current elevation: 364.81 m
Projected peak: 364.87 m on or near August 14, 2020
Present Elevation: 9.93 m (2320 m3/s)
Forecasted peak: 10.23 m (2440 m3/s) on or near August 15
- Meeting Lake has received approximately 275-300 mm of Precipitation since April 1 ,2020 (~150% normal)
- July 22, 2020 lake level is 739.48 m
- 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)
Present Elevation: 267.75 as of 8:00 AM July 24, 2020
Forecasted peak: Peak observed on July 23, 2020
Light rain over the Reindeer Lake area is expected today as the system that had been impacting northern Saskatchewan makes its way into Manitoba. Additional rainfall is expected over the weekend with central areas of the Churchill Basin expected to receive the highest accumulations with general accumulations of 10-20 mm expected and localized higher amounts within thunderstorms.