by Watershed Stewardship Assistants, Shannon Hart and Conlan Donahue
Marvin Gaye’s “Ain’t no mountain high enough, to keep me from getting to you,” may be the lyrics this year’s spring runoff will be singing as it makes its yearly descent down the Rockies. Spring seems to be flirting with Southern Alberta, teasing with sunshine that brings blue skies and budding trees. After a long winter, the warm weather is a welcome addition to our days as gardens and crops are planted, migratory birds return, and the land gently turns from brown to green. However, there is one recurring question that goes unanswered: drought. The potential for more drought is weighing on the people of Southern Alberta and there are predictions of high summer temperatures for the Prairie provinces this summer; this leaves many wondering what the water supply will look like for 2023.
The Necessity of Water
How much water is required for Southern Alberta to keep operating? Unlike other watersheds whose surface water is provided by glaciers, the Oldman watershed’s water supply comes from snowpack in the mountains and rain throughout the year. Receiving more snow and rain means that there would be a reduced reliance on pumping water out of our rivers and creeks to meet our needs.
Photo by Connie Simmons
The average Albertan personally uses about 7,000 litres of water per month. This is for common day-to-day tasks such as showering, cooking, cleaning, and watering lawns. Living in Canada’s Premier Food Corridor means that industries such as agriculture and manufacturing also require large amounts of water in order to operate successfully. Water is a crucial component of all residents' everyday life. Before diving into the water supply forecast for 2023, we should consider the current water conditions in the Oldman watershed.
Current Conditions
What does the water supply look like in the Oldman watershed? The Government of Alberta’s Agricultural Moisture Situation Update for May 10, 2023 states that current soil moisture reserves (i.e. previously fallen precipitation that is stored in the ground) are shown to be normal for most of the Oldman watershed, with moderately low to low levels near the Blood 148 Reserve, and the confluence of the M.D of Willow Creek, M.D of Pincher Creek, and Cardston County.
Alberta Soil Moisture Reserves (Alberta Agricultural Moisture Situation Update)
Precipitation levels are mapped as normal to moderately low in the Oldman watershed. Throughout November 2022 to April 2023, Lethbridge received 141.2 cm of snow. Since January 1, 2023, Lethbridge has received 67.4 mm of precipitation as both rain and snow, of which 15 - 30 mm was spring rain that has fallen in the Oldman watershed since the beginning of April.
Rain, Rain, Come This Way!
Precipitation is an important factor in our watershed not only for soil moisture, but reservoir storage as well. There are three major onstream storage reservoirs in the Oldman watershed: the St. Mary’s, Waterton, and the Oldman. The purpose of these structures is to provide a constant and secure source of water because precipitation is unpredictable during the growing season. The Oldman reservoir is currently sitting at 64% of full capacity, the Waterton reservoir is recorded as being at 38% capacity, and the St. Mary’s reservoir is currently at 46% volume of total capacity. Collectively, the ten reservoirs in the Oldman basin have an average storage level of 70% full capacity.
Currently, the flow level of the Oldman River at a station near Lethbridge is at 25.34 m³/s (cubic metres per second). To supplement that information, the Alberta River Basins app has also calculated flow rates for the upcoming months. According to the graph below, we may soon begin to see an influx of water coming through the Oldman River near Lethbridge, which will eventually decrease as we head into August.
Calculated flow and water level for the Oldman River near Lethbridge (Alberta Rivers App).
Oldman Snowpack
The mountain snowpack accumulations measured in our mountains as of April 1, 2023 show much below average to average levels. Six sites were surveyed, with accumulations ranging from 74% of the yearly snowpack levels at Westcastle to 97% at South Racehorse Creek; there is an outlier of 247% at Lee Creek.
The Spring Runoff Potential map shows that all of the snow residing on and in our prairies of the Oldman watershed has melted. This suggests a reliance on reservoir storage and mountain runoff in the form of snowpack for the 2023 growing season.
Spring Runoff Potential Map (Alberta’s Rivers Website)
2023 Water Supply Forecast
On April 12, 2023, the mountain runoff forecast for the Oldman River Basin was recorded as much below average to below average for the predicted period of March to September 2023. This is most likely due to the fact that the recorded volumes in March were much below average. The April to September forecast indicates much below average to average amount of mountain runoff in 2023.
According to Environment Canada (issued on March 31, 2023), there is an equal chance of receiving below normal, normal, or above normal amounts of precipitation in Southern Alberta from April through June 2023. There is also an equal chance of below normal, normal, or above normal temperatures coming to Southern Alberta from April through June 2023.
Precipitation and Temperature Probability Forecast April/May/June 2023 (Environment and Climate Change Canada Website)
El Niño, En Route
The El Niño-Southern Oscillation (or ENSO) is a climate pattern defined by sea surface temperature and precipitation levels across the equatorial Pacific Ocean. El Niño is the warm phase of ENSO when ocean temperatures are warmer and precipitation is unevenly distributed across the world. El Niño has a colder sibling phase called La Niña, and a transitional neutral phase as well. These systems have the ability to influence weather and climate patterns around the world. Phases typically occur every 3 to 5 years.
As of April 13, 2023, theNational Oceanic and Atmospheric Administration (NOAA) has come out with an ENSO Alert System Status: El Niño Watch. This has been issued because conditions are favourable for the development of El Nino within the next six months. While we are still in an ENSO-neutral phase—where no El Niño or La Niña is present—there is a greater than 90% chance El Niño will develop sometime in the next couple of months and persist into our Northern Hemisphere's winter. This is projected to affect the Canadian climate after more than two years of being in the La Niña phase.
Photo by Jeremy Wind
Beyond influencing the weather, these global changes can produce ripple effects that influence food supplies and prices, forest fires, and spur further economic and political consequences. NOAA scientists continue to monitor the potential development of El Niño.
Conclusion
Water availability in the Oldman watershed is one of the most important factors in quality of life, economic success, politics, and ecosystem stability. Preparing for and planning how to mitigate water shortages is a crucial component of maintaining a successful business for many residents in our watershed. Low precipitation levels, below-average mountain snowpack, and average reservoir storage make 2023’s water supply forecast a bit gloomy. An El Niño event could be approaching, and with water supply forecasts providing important insight into what the growing season will look like in 2023, it’s safe to say that water will be a hot topic this summer.
Banner photo by Shannon Hart
