Water Supply Conditions and Outlook and Rivers... · the south central and southeastern portions of the province are ... the southeast, particularly the Indian Head and Wolseley area

Water Supply Conditions and Outlook Based on Conditions as of October 1, 2020

Prepared by: Flow Forecasting & Operations Planning - Water Security Agency

Water Supply Outlook – Conditions as of October 1, 2020

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Overview

Major surface water supplies across the province remain

adequate with most major reservoirs near their full supply level or

at near normal levels for this time of year. The dry conditions in

the south central and southeastern portions of the province are

causing impacts to surface water users who rely on dugouts and

other small surface water supplies. This includes both the surface

water supply issues, as well as impacts to the quality of the

surface water.

So far this fall, northern areas of the province received

precipitation amounts that ranged from below normal in the

Churchill River Basin, to well above normal in the far north central

area. Stream flows, particularly in the Churchill River and

Athabasca River basins, remain well above normal following the

wet summer conditions. As a result, the High Streamflow Advisory

remains in effect. While flows are slowly receding on the system,

they are expected to remain well above normal throughout the fall

and into winter. While significant flooding did not occur, the high

flows continue to pose a risk to the safety of the public.

In contrast, much of southern and central portions of the province

are experiencing conditions that are generally drier than normal.

The exception is the southwest along the Alberta border where

conditions so far this fall have been closer to normal. Currently,

the south-central portion of the province is experiencing the driest

conditions.

Flows on the North Saskatchewan River and Saskatchewan River

remain near normal. Inflow into Lake Diefenbaker are now closer

to normal. Releases from the Coteau Creek Power Plant at

Gardiner Dam are near median level. With inflow close to outflow,

Lake Diefenbaker remains at above normal elevations for this

time of year. Fall drawdown operations on Lake Diefenbaker are

expected to take place later this month.

Fall operations are also taking place in the Qu’Appelle River

basin, resulting in lower flows above Pasqua lake and higher flows

downstream of Echo Lake as lakes are drawn down.


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Spring 2020 Precipitation Summary

Figure 1 shows precipitation accumulations in September and

Figure 2 depicts the same information as a percentage of normal.

Rainfall in September ranged from lows of only trace amounts in

south central areas near Coronach, to highs of over 70 mm in the

Stony Rapids area in the far north.

In the north, much of the western portion of the Churchill River

Basin received below normal precipitation with 10 to 25 mm

being recorded (40-80% of normal). There were some small

pockets that received closer to 50 mm which is near normal. The

eastern portion of the basin, and much of the far north received

40 to 60 mm (100-110% of normal). The area in northcentral,

around Stony Rapids, received upwards of 70 mm or about 140%

of normal accumulations.

Most of southern and central portions of Saskatchewan received

trace amounts to 30 mm throughout the month of September,

which is 0 to 60% of normal. The exception to this was the

southwest corner in the Consul and Maple Creek area which

received 40 to 60 mm (100 to 140% of normal), and the area

north of Prince Albert where 45 to 70 mm (100 to 140% of

normal) was recorded.

When looking at the April 1 to September 30 period (Figure 3),

the southeast, particularly the Indian Head and Wolseley area

south to the US border, received below normal precipitation

accumulations this growing season. The remainder of the grain

belt generally varied from below normal in south eastern and east

central areas to well above normal amounts in the North

Battleford and Cumberland House area. Exceptionally high

accumulations were received across most of the northern portion

of the province.

Figure 1: Precipitation Accumulations

September 1st to 30th, 2020


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Figure 2: Percent Normal Precipitation

September 1st to 30th, 2020

Figure 3: Precipitation Percentiles – April 1 to Sept 30, 2020

(Map courtesy of Agriculture and Agri-Food Canada)


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Moisture Conditions

Figure 4 shows cropland topsoil moisture conditions as of

September 28, 2020. Throughout September, topsoil moisture

conditions improved some in the southwest, with conditions

ranging from short to adequate. Topsoil moisture conditions

across southcentral portions of the province have declined with

more areas now reporting very short conditions. Conditions in the

southeast have also been generally drier, with now only a small

area north of Weyburn and a small area northeast of Broadview

reporting near normal conditions. In central portions of the

province, conditions generally range from short to near adequate,

with some small pockets reporting very short conditions.

Agriculture and Agri-Food Canada’s remotely sensed soil

moisture product (Figure 5), indicates conditions are drier than

normal across much of southern and central Saskatchewan, with

the exception of the west along the Alberta border where

conditions are closer to normal. This figure also shows that

throughout most of the Churchill River Basin, soil moisture

conditions are now range from near to slightly above normal.

Conditions remain wetter than normal through the northwest

around Lake Athabasca and areas further south along the Alberta

border.

The Canadian Drought Monitor assessment for August 31 (Figure

6) shows abnormally dry conditions are being experienced across

all of southern Saskatchewan and in a good portion of the central

portions of the province, particularly the Saskatoon and Prince

Albert area. The area around Saskatoon and to the southeast

stretching down to near Broadview, and an area south of Moose

Jaw is experiencing moderate drought conditions. Abnormally

dry conditions are also being experienced in the extreme

northwest and in southern portions of the Churchill River Basin.

The October 1 map was not available at the time of this

publication, but it is expected that conditions would have

improved some in the southwest and possibly declined across the

remainder of the south.

Figure 4: Cropland Topsoil Moisture Conditions as of Sept. 28,

(Map courtesy of Saskatchewan Ministry of Agriculture)


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Figure 5: Topsoil Moisture Conditions October 4, 2020



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Figure 6: Canadian Drought Monitor – August 31, 2020



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Long-Range Forecasts

All long-range forecasts are currently predicting above normal

temperatures over Saskatchewan for October 1 to December 31,

2020. Near normal precipitation is forecasted across much of the

province over this period. The exception is the far north where

above normal precipitation is forecasted by most models.

Multi-model ensemble maps for precipitation and temperature for

this three-month period, which are the average result of seven

seasonal forecasts, are shown in Figure 7 and 8, respectively.

It is important to keep in mind that seasonal weather forecasts

are statistically unreliable.

Figure 7: North American Multi-Model Ensemble Precipitation

Anomaly Outlook for October 1 to December 31

(Map courtesy of the US National Weather Service)

Figure 8: North American Multi-Model Ensemble Temperature

Anomaly Outlook for October 1 to December 31

(Map courtesy of the US National Weather Service)


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Detailed Water Supply Conditions

Table 1 provides a summary of the current levels and storages of

the major water supply lakes and reservoirs in Saskatchewan.

Most reservoirs are either near or above normal levels for this

time of year. The exception are the reservoirs in the Souris Basin,

and Huff Lake, which are all slightly below median for this time of

year; however, all water demands are being met.

Table 1: Water Supply

Reservoir Date of

Observation Elevation

(m)

Full Supply

Level (m)

Departure from Full

Supply (m)

Current Storage (dam3)

Current Percent

Full

Lower Quartile Elevation (m)

Median Elevation (m)

Upper Quartile Elevation (m)

Altawan October 1, 2020 898.99 899.71 -0.72 5,380 81% 893.77 896.55 897.89

Avonlea October 1, 2020 597.01 597.90 -0.89 6,820 77% 596.43 596.96 597.50

Boundary October 1, 2020 559.53 560.83 -1.30 53,300 88% 558.38 559.88 560.24

Buffalo Pound October 1, 2020 509.54 509.47 0.07 96,000 102% 509.29 509.38 509.45

Cookson October 1, 2020 752.25 753.00 -0.75 35,600 87% 750.70 751.71 752.19

Cypress October 1, 2020 975.33 975.97 -0.64 112,000 88% 971.34 972.79 974.38

Diefenbaker October 1, 2020 556.13 556.87 -0.74 9,080,000 97% 555.14 556.01 556.45

Downie* October 1, 2020 877.01 878.89 -1.88 7,780 64% - - -

Eastend October 1, 2020 917.73 918.06 -0.33 2,090 82% 915.53 916.19 916.89

Grant Devine October 1, 2020 560.88 562.00 -1.12 92,900 88% 560.93 561.06 561.45

Highfield October 1, 2020 721.53 722.99 -1.46 8,030 54% - - -

Huff October 1, 2020 813.65 815.72 -2.07 872 20% 813.32 814.00 814.79

Junction October 1, 2020 755.10 757.28 -2.18 5,360 41% - - -

Newton October 1, 2020 802.75 803.28 -0.53 9,530 77% 800.58 801.44 802.08

Nickle October 1, 2020 562.28 563.00 -0.72 10,300 78% 562.32 562.62 562.90

Rafferty October 1, 2020 548.68 550.50 -1.82 356,000 81% 547.82 548.98 549.54

Reid/Duncairn October 1, 2020 806.77 807.72 -0.95 90,600 86% - - -

Thompson/Lafleche October 1, 2020 714.23 714.76 -0.52 32,600 88% - - -

*Data courtesy of Agriculture and Agri-Food Canada


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Major River Systems

Saskatchewan River System

The Alpine region of both the North and South Saskchewan rivers

generally recorded higher amounts of precipitation compared to

the dry conditions across much of the prairie and foothills region

of the basins during September. Flows on the North

Saskatchewan River have continued to recede yet remain near

median for this time of year. Flows are expected to continue to

slowly recede throughout the coming weeks.

With the dry conditions across Southern Alberta, flows into Lake

Diefenbaker were below normal throughout much of September;

however, with the end of the irrigation season in Alberta, inflows

did climb back to near normal by the end of the month. Inflows

are expected to remain at near normal throughout October and

into November. WSA has continued to rely on storage to maintain

more desirable flows downstream of Lake Diefenbaker as the

reservoir is above median levels. The plan is to maintain mean

daily outflows near 120 m3/s over the next couple of weeks and

then start to stage up releases to 160 m3/s by the third week of

October. These flows would be near normal for October.

With the inflows and outflows near the same, and water use and

evaporation at the reservoir declining, the reservoir level has

remained fairly stable throughout the later half of the month. This

level is expected to remain near the same until SaskPower begins

their freeze-up operations later this fall. The reservoir is expected

to enter winter slightly above normal, with levels dropping down to

554.5 to 555.0 m by the end of the year.

With nearn normal flows on the North Saskatchewan River and

near normal releases from Lake Diefenbaker on the South

Saskatchewan, flows remain near normal on the Saskatchewan

River.

Figure 9: Lake Diefenbaker Observed and Forecasted

Inflows

Figure 10: Lake Diefenbaker Observed and

Forecasted Elevations


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Qu’Appelle River

As winter approaches, fall operation plans are gradually being

undertaken across the Qu’Appelle River basin. In the Lower

Qu’Appelle, the release from the Craven control structure was

terminated on September 28, leaving just the fishway open with

about a 1.0 m3/s flow. Some of the logs from the Crooked Lake

and Echo Lake control structures were removed on September

29 and 30. Considering the dry condition in the Qu’Appelle River

system, the plan is to leave some logs in the Echo Lake control

structure over the winter. All the Qu’Appelle Lakes are expected

to drop to their desirable fall water levels within the next few

weeks.

A rehabilitation work is planned in the Upper Qu’Appelle channel

starting in early October. The Qu’Appelle River Dam release was

terminated on October 1, prior to the work. To compensate for

the evaporative loss during the rehab work, Buffalo Pound Lake

was surcharged in advance. Once the work is completed, a

typical winter flow will be established.

Additional rehab work is planned on the Echo Lake control

structure, scheduled for late October/early November, and the

construction of a rock riffle fishway is planned at the outlet of

Katepwa Lake which is expected to be completed by the end of

October.

Table 2: Observed and Forecasted Qu’Appelle Lake Levels

Lake 2020

Spring Peak

Oct 1, 2020

Projected Nov. 1, 2020

Desirable Fall Operating

Range

Buffalo Pound 509.67 509.54 509.32 509.32 – 508.87

Last Mountain 489.98 489.75 489.70 490.00 – 489.36

Pasqua-Echo 478.82 479.00 478.85 478.84 – 478.54

Mission-Katepwa 478.48 478.20 478.25 478.08 – 477.77

Crooked 451.55 451.40 450.85 451.56 – 451.10

Round 441.82 441.61 441.52 442.11 – 441.66

Souris River

With the below normal rainfall received across most of the basin

this summer, all the reservoirs on the system remain at below

normal elevations for this time of year; however, all water supply

demands are being met within the basin.

At this time, no winter releases are anticipated as both Rafferty

and Grant Devine reservoirs are below their February 1 target

drawdown levels. A release from Rafferty will however be made in

mid-October to replenish downstream supplies.

Figure 11: Lake Diefenbaker Observed and Forecasted

Outflows


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Quill Lakes

The Quill Lakes area received well below normal rainfall, with only

about 21 mm of precipitation recorded throughout September.

The lake level is currently near 520 m. Evaporative losses thus far

in 2020 have amounted to about 0.36 m resulting in lake levels

that are about 0.24 m lower than the start of the year.

Churchill River

Flows have remained well above normal across the Churchill

River Basin throughout September but are slowly receding.

Currently, the flows in the upper portions of the Churchill River

remain flowing at around a 1:25 year return period. Flows in the

lower portions peaked in early August and are currently flowing at

well above normal levels for this time of year. Without significant

rain, flows are expected to continue to slowly recede throughout

October.

With the rain received throughout the summer months, Lac La

Ronge reached an elevation peak late in August, and has since

started to recede; however, the elevation still remains well above

the desirable operating range. The High Streamflow Advisory will

remain in effect for the basin for the month of October.

Even though the peaks have been observed on the system, flows

in the Churchill River Basin are expected to remain well above

normal throughout the fall and into the winter.

Southwest

Rainfall throughout September in the southwest generally was

near to slightly above normal across most of the region with the

exception of the Old Wives Lake Basin and lower portions of the

Frenchman River Basin which recorded below normal

accumulations. With many of the reservoirs in the southwest

starting off the 2020 season at above normal elevations, the hot

dry weather throughout the summer, and in some areas, into the

fall, has not significantly impacted water supply sources across

the region. The only reservoir that is currently below the normal

elevation for this time of year is Huff Lake on the Frenchman River

system, but this is the result of a drawdown to facilitate some

rehab work.

Table 3 contains October 1st water levels for a cross section of

Saskatchewan lakes. Note that wind may have been impacting

some of these water level estimates.

Domestic Water Supplies

Figure 12 below shows the impact to surface water supply across

the province. This map shows that there are surface water issues

across most of southern Saskatchewan. These impacts are

potentially affecting users who rely on dugouts and other small

surface water supplies. The hot and dry conditions experienced

throughout the summer and into the fall has also impacted the

quality of surface water across much of the south.


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Figure 12: Agroclimate Impact on Surface Water Supply as of September 30, 2020



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Table 3: Lake Level Summary

Lake October 1, Levels (m)

Fall 2020 Projected Levels (m)

Normal Summer Level (m)

Recorded Historical Extreme

Level (m) Year

Anglin 515.39 515.35 515.35 515.99** 2013

Big Quill 519.97 519.95 515.00 520.93** 2017

Boundary Reservoir 559.53 559.5 560.50 561.15 1979

Buffalo Pound 509.54 509.3 509.47 511.45 1974

Candle Lake 494.26 494.25 494.40 495.25 1973

Cookson Reservoir 752.25 752.5 752.50 753.35 1979

Crooked 451.38 451.4 451.70 454.40** 2014

Echo and Pasqua 479.06 478.8 479.10 480.98 2011

Fishing 529.72 529.8 528.50 530.92 2011

Good Spirit 484.14 484.1 484.60 485.68** 2010

Grant Devine 560.88 561.8 561.50 556.58** 2011

Jackfish 529.51 529.5 529.40 530.00 1985

Katepwa and Mission 478.19 478.25 478.30 479.58 2011

La Ronge 364.84 364.8 364.30 364.98** 2011

Last Mountain 489.84 489.68 490.20 492.09 1955

Moose Mountain 619.91 620.0 620.40 621.90 2011

Rafferty 548.68 548.7 550.50 554.05** 2011

Round 441.63 441.52 442.4*** 445.70** 2014

**Occurred after spring runoff during summer event(s)

***With outlet structure operated. Without the outlet structure the normal summer level is 441.3m


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Ongoing Water Supply Outlook

Up to date flows and lake levels are available at www.wsask.ca.

This will be the final Water Supply Conditions Reports for 2020. WSA will issue their Conditions at Freeze-up Report in November.

http://www.wsask.ca/

Documents

Water Supply Conditions and Outlook and Rivers... · the south central and southeastern portions of the province are ... the southeast, particularly the Indian Head and Wolseley area