The misunderstood mountain waters that Albertans depend on

Cathy Ryan collecting water samples from a spring near Lake Louise (under a Parks Canada Research Permit) to conduct analyses that will ‘fingerprint’ what water looks like coming from the bedrock. The lush groundwater-dependent ecosystem is protected by a ski team who call it ‘Fairy Land.’ Photo credit Dave Bethune.

It’s early spring, and the Eastern Slopes of the Rocky Mountains are laden with snow. For the skiers awaiting the next chair up the hill, hydrology is probably the last thing on their minds. Cathy Ryan, however, sees the landscape differently.

“I spend almost all my time in the mountains thinking about water flowing underneath my feet,” says Ryan.

It’s on her mind for a good reason. When she’s not hitting the slopes at Lake Louise as a ski volunteer, Ryan dedicates her time to studying the connections between mountain headwaters and river flow as a University of Calgary professor in the Department of Earth, Energy and Environment. Everywhere she looks, there are signs of impressive volumes of water moving through the mountains.

“When I get on the Ptarmigan chair lift at Lake Louise, Corral Creek flows right underneath it, and one of our graduate students has a data logger there,” says Ryan, “and when you go up the Glacier Express chair, you can see groundwater seepage coming out of the Miette formation all winter long in a unique groundwater-dependent ecosystem the local ski club calls ‘Fairy Land.’”

These landscape features are much more than an object of curiosity. They are part of an extensive and mysterious network of flow pathways which deliver water from the mountains into some of Alberta’s most important rivers.

The surprising origin of the Eastern Slopes rivers

The Eastern Slopes are cherished not only for their iconic beauty, but for their lifegiving waters. More than 90 per cent of the water Albertans drink or use for irrigation comes from the Eastern Slopes, whose headwaters sustain rivers that stretch across the prairies. This includes the Elbow and Bow Rivers, which supply water to Calgary’s over 1.3 million residents. It’s no exaggeration to say that the well-being of Alberta depends on the mountains, and when drought hits the Eastern Slopes, the impacts are felt far downstream.

With so much at stake, it’s important to understand exactly how those headwaters function. In the mountains, visible water takes on many forms – from glacial ice to snowy peaks to vibrant alpine lakes. But while these spectacular surface features steal the show, the mountain slopes disguise another water source. If you could make all the towering rock and soil invisible, you would see an astonishing network of groundwater reservoirs. This subsurface network extends from the high peaks down to the valley bottoms, making connections with surface water all along the way. When groundwater does make its way back to the surface, it can easily go unnoticed, filling a waterbody from the bottom up. This is called base flow, and while it’s what keeps a lake full or a river flowing in the absence of rain or snowmelt, it rarely gets the appreciation it deserves.

“Most of the attention in Canada goes to surface water, not to groundwater, partly because groundwater is super difficult to understand and monitor,” says Ryan. “It’s hard to envision the subsurface and it’s also really expensive to study, so most people just think about surface water.”

As climate change has begun to alter patterns of precipitation in the mountains, researchers have directed their focus to the connections between surface water and climate, often assuming that groundwater is ultimately not changing very much. The assumption is that rain and meltwater take a more or less direct path into the rivers below, only briefly dipping into the subsurface along the way. However, recent evidence has turned this assumption on its head.

“Hydrologists have this working paradigm that the groundwater is just a short-term ‘pipeline,’ and that it’s really snow melt and rain that are important,” says Ryan, “but the water in the Elbow River has an average age of about five to ten years since it fell as precipitation. There are no appreciable glaciers in the Elbow River watershed and snow lasts for less than one year. So that five or ten years was spent mostly as groundwater.”

As it turns out, a drop of rain or melted snow could take a long time to reach the rivers at the base of the mountain. Instead, it may enter the subsurface and move at varying flow rates in the mountain as groundwater for years, decades or even millennia. PhD work by Éowyn Campbell, now a lecturer at the University of British Columbia’s Okanagan campus, found that two thirds of the water in the Elbow River came directly from groundwater.

This poses big questions for researchers trying to predict how climate change will impact Alberta’s water supplies. How exactly do these groundwater reservoirs contribute to rivers leaving the Eastern Slopes? How much water is diverted into them, and how quickly do they fill up? Could these reservoirs dampen a bad drought, or only delay its impact? 

Nadine Taube (watershed scientist, AEPA, pictured left) and Kendall Marshall (MSc candidate, University of Calgary, pictured right) working to deploy a remote-controlled acoustic flow meter to measure Bow River discharge under the supervision of May Guan (meteorological and hydrometric technologist, AEPA)

Women in water rising to the challenge

A new research initiative, led by scientists at the University of Calgary and Alberta Environment and Protected Areas (AEPA) and funded by Alberta Innovates, is getting to know these groundwater systems on a deeper level. The three-year project kicked off in 2023 and aims to quantify the main water sources and their flow pathways through the Eastern Slopes. The project will also examine how climate change is affecting these water sources across different time scales. The project is expected to provide new insights into groundwater flow that can be incorporated into modelling and prediction of Alberta’s water supplies, supporting more effective water management at provincial, municipal and watershed council levels.

Groundwater is notoriously hard to study even in the best of circumstances – let alone on remote mountain slopes where access is difficult. An undertaking of such scale requires a dedicated and multidisciplinary team. The project is co-led by five scientists, including Ryan and Jianxun (Jennifer) He at the University of Calgary, and three AEPA researchers: Brandi Newton, hydroclimatologist; Jean Birks, hydrogeologist; and Nadine Taube, watershed scientist. Campbell, whose initial work on the Elbow River largely inspired the project, also supports the team as a research associate.

“A quite remarkable thing about this project is that there’s five female co-leads on the original proposal. I’ve never worked with two before, let alone five,” says Ryan.

The project leads all take part in co-supervising graduate students. Together with postdocs and interns, they form a talented and intrepid team of mostly early-career researchers who are just as comfortable in hiking boots as they are in the lab. Armed with probes, dataloggers and sample bottles, they’ve collected data from across the Eastern Slopes, each tackling a different piece of the groundwater puzzle.

Tracing water flows from peak to valley

To understand the role groundwater plays in river flow, you need to understand how it reaches the river in the first place. Several core project components investigate flow pathways down the mountains and the interactions between groundwater and surface water along the way.

Starting in the highest alpine, one sub-project involves sampling water from a streams in a small, glaciated watershed to determine how much of the stream flow is actually coming from glacier melt, versus snow, rain or groundwater.  Initial findings suggest that groundwater contributes a surprising portion of the total stream flow at the bottom of the small watershed, even at these high elevations.

Continuing down the mountain, water flowing through the subsurface will travel through a series of groundwater reservoirs. Along the way, some groundwater may re-emerge to the surface of an alpine lake before flowing on to lower elevations. One sub-project examines two of these lakes more closely to understand how much groundwater is sustaining the lake levels, as well as how much groundwater simply passes through the lake. This is important because lakes may play a key role in downstream water supply through the groundwater zone, although little is known about their contribution. 

When lake levels drop over the winter, it is a sign that the water is seeping into and out of the lake and it could be sustaining the base flow of rivers down below. A mountain lake may be an important reservoir for rivers in times of drought, despite no obvious surface connection between the two. 

The sub-project focuses on two lakes at different elevations: Zigadenus Lake, an alpine lake located just below a glacier, and Elbow Lake, a lower elevation lake near the treeline with no glacier and fed only by groundwater. Zigadenus Lake is nested in older rock formations compared to Elbow Lake, which gives each lake and its corresponding groundwater complex a unique signature. Through analysis of the dissolved minerals in the lake water, the team is able to determine where the water originated.

“For example, the tap water that we drink has calcium, magnesium and bicarbonate as major ions because carbonate rocks are both common and pretty soluble in the watershed.  The kinds of major ions that are in river water and groundwater naturally tell you about which rocks it’s flowed through. More time and distance in the groundwater system imparts more solutes into it,” says Ryan.

Following the flow of the Bow

Down in the valley bottom, another sub-project looks at the mainstem Bow River itself to understand how different groundwater sources contribute to its total flow. Flow measurements have been taken at as many as five sites between Bow Lake and Exshaw in collaboration with AEPA. The measurements were taken in early November, when the snowpack is frozen and the river is mainly supplied by groundwater base flow. Initial findings have shown that groundwater systems make a disproportionate contribution in some reaches.

At the start of the river where it leaves Bow Lake, its flow is a tiny fraction – only 1.5 per cent – of what will ultimately reach Calgary. As the river moves downstream, it picks up more and more base flow from the surrounding mountains. As the river passes Lake Louise and Banff, its flow level increases to 38 per cent. The biggest contribution, however, occurs between Banff and Canmore, where almost all of the remaining flow enters the river, bringing it to over 95 per cent of Calgary’s flow level. This means over half of the river water that reaches Calgary originates from the mountains between Banff and Canmore. Using geochemical and isotopic analysis, the team is working to pinpoint more specifically which aquifers in that mountain stretch are generating the flow.

Examining climate change, past and future

All this adds up to a clearer picture of the mysterious groundwater networks of the Eastern Slopes. But how will those networks change, particularly as Alberta faces increasing drought?

“The mountains are unduly affected by climate change. Talk to any skier and they’ll tell you that we have shorter, warmer winters,” says Ryan.

Drawing on 20 years of major ion data provided by the City of Calgary and Environment and Climate Change Canada, another key project component examines changes in the Bow River’s water sources across seasons, years and decades. Initial work shows that climate change is associated with an increase in carbonate solutes – an indicator that groundwater from carbonate aquifers is making up a growing proportion of the water flowing to the prairies. This underscores the importance of these groundwater reservoirs in Alberta’s critical water supplies.

“We have warmer winters with more precipitation as rain, more groundwater recharge, and what we’re seeing in the solute composition of the Bow River is that carbonate solutes are increasing on a decadal scale, but the flow is not increasing,” says Ryan, “so that means there’s more groundwater contribution   to the river.”

Another sub-project examines the effect of drought specifically. The aim is to better understand the main drivers of drought in the Eastern Slopes watershed and how reduced rain and snowfall propagate through groundwater and stream flow. Ultimately, the end goal is to understand groundwater well enough to develop a more accurate river flow forecasting model, so that scientists and decision-makers can more easily anticipate and manage changes in water supply.

Under the iconic Three Sisters Mountains, flax flowers grow on the surface of an alluvial aquifer which provides water supply to the Town of Canmore.

Looking forward

The Eastern Slopes headwaters are a critical resource for Albertans far and wide, and the project team works closely with the communities that depend on those waters. The Bow River Basin Council and the Town of Okotoks host local interns who support the project in everything from field data collection to lab work. Each intern is also expected to participate in knowledge extension, reporting back to their host municipality on topics of local concern.

AEPA, the City of Calgary, the University of Calgary and Alberta Innovates are also key partners on the project, whose funding and in-kind contributions make the research possible.

“Alberta Innovates is a major funder of water research in Alberta, and we’re really happy to be working with them,” says Ryan.

As the project enters its third year, the team hopes to refine their mapping of the surface and groundwater connections and make steps towards integrating that knowledge into flow models for the region. The vision is to equip Albertan communities with the knowledge and tools needed to manage water sustainably and improve drought resilience, now and in the future.

In the meantime, Ryan can’t help but feel a sense of awe at the groundwater complexes around her. Knowing where to look, maybe you will too.

“When I’m driving on the highway between Canmore and Banff, I look at the frozen waterfalls,” says Ryan. “The thing about those waterfalls is that it’s actually groundwater that was seeping out before it froze. You look at how high they are, and unless there’s a lake right above it, that’s how high the groundwater table is.”

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.