What lies beneath: unraveling the secrets of the North Saskatchewan River

Groundwater spring in Edmonton.

If you live in Edmonton, deep beneath your feet is an invisible network of ancient stream beds, long covered by glacial deposits. These formations now serve as underground reservoirs – known as aquifers – containing an abundance of flowing groundwater, some of which seeps into the North Saskatchewan River.

In Edmonton and surrounding areas, 1.5 million residents depend on the river daily for freshwater, yet how much of the river’s water originates from local aquifers compared to surface tributaries is unknown. It is also unclear whether new groundwater wells could serve as an alternate water source for the city when the river supply is low.

Understanding these complex groundwater systems is critical to maintaining reliable water supply over the coming decades.

A multidisciplinary team of researchers from the University of Alberta, partnered with EPCOR, the North Saskatchewan Watershed Alliance and scientists at the Alberta Geological Survey set out to untangle the connections between groundwater and surface water in the Edmonton region of the North Saskatchewan River Basin.

“We were curious about the role of groundwater when we start to think about water sources to the river and future water security issues,” says Brian Smerdon, research associate at the University of Alberta.

This curiosity extended to considering emergency scenarios like extreme drought or contamination events, which may become more frequent under climate change. Piecing together the river’s geochemistry, however, has been a complex puzzle. Under the guidance of the lead researchers, graduate students from the University of Alberta have examined the river’s journey from the Rocky Mountains to the plains, using water balance models to estimate rain, snow melt and glacier contributions, while sampling tributaries and groundwater wells in the Edmonton area to understand groundwater connections.

“Mapping conducted 40 to 50 years ago identified many of these aquifers, but no one latched onto them,” says Daniel Alessi, professor and Encana Chair in Water Resources at the University of Alberta.

The team found that while the hidden aquifers contain enough groundwater to act as a potential water source, their limited volume might only be sufficient for emergency scenarios.

“These aquifers are only going to be useful for a portion of the year or a small period of time while we find an alternative water source,” says Smerdon.

When it comes to the contribution of groundwater to the North Saskatchewan River, seasonal variation plays a crucial role. Water seeping into the river from groundwater, known as base flow, drops to near zero as the river flows into the Edmonton area. During late fall or very dry spells, the river might even lose more water into the aquifers than it gains.

While this research has provided insight into the river’s journey from the mountains to the prairies, what’s going on at the urban level in Edmonton is unclear. The next research phase aims to examine the depth of groundwater and the connections between groundwater and surface creeks within the city, which also feed into the river. This data could provide insight into urban development and its potential impacts on creek flows within the watershed.

Smerdon says the support Alberta Innovates has provided to enable this research has been invaluable: “It’s been a real advantage to have a program that is nimble on its feet and able to adapt to changes we find interesting.”

Learn more about Alberta Innovates’ Water Innovation Program.

This article is part of Making Waves, an annual Alberta Innovates publication highlighting water solutions we support. You can read more stories from this issue below.