What are Springs?Springs are part of the water cycle. When water falls as precipitation it seeps into the ground and, over time, it makes its way into permeable layers of rock, sand, and gravel. These layers are called aquifers and they allow the water to flow through them at different rates which depend on the layer’s permeability. Springs occur in areas where an aquifer is filled to the point that groundwater overflows onto the land surface and creates visible flow. We see springs at the land surface (sometimes referred to as a groundwater outcrop) or underwater. Springs at the land surface are seen on cliff faces, hillsides, riverbanks, or along road cuts, and underwater springs occur beneath a lake or river.
Alberta SpringsSprings play a critical role in understanding hydrogeology and the quality of groundwater in aquifers, which many Albertans rely on for water. Over the past 100 years, we have intermittently researched and documented information about Alberta’s springs beginning with Dr. John Allan’s search for economic minerals in the 1920’s. Our knowledge of the relationship between groundwater and springs grew with Dr. Jóseph Tóth’s landmark hydrogeological papers in the 1960’s, the technological advances with computing and databases in the 1990’s, the introduction of mapping using geographic information systems (GIS) in the 2000’s, and finally with remote sensing applications in the past decade.
Common Types of Springs
Not all springs are created equal. They can be hot or cold, small or large, seasonal or perennial, salty or fresh. There are many types of springs. Some of the more common springs in Alberta are:
Contact Springs occur at the contact of two layers of rock with sharply contrasting permeability such as a sandstone aquifer resting on top of shale. When the aquifer is exposed from erosion (or other means), the groundwater flows or seeps out creating a spring.
Fracture springs occur where groundwater flows or seeps out from breaks in the rock such as planes of cleavage, bedding, joints, or faults. An example of a fracture spring is the one that supplies water to the Raven Fish Hatchery near Raven, Alberta.
Thermal springs are less common in Alberta, however they tend to be more interesting to the public for their perceived health benefits. These are formed when groundwater seeps down deep into the earth and is warmed by geothermal activity. The heated water expands and makes its way back to the surface through breaks in the rock (joints, faults or fissures) where it flows or seeps out before it has time to cool. The Miette Hot Springs near Jasper and the Cave and Basin Hot Springs near Banff are excellent examples of thermal springs.
In some areas of Alberta there are layers of limestone or dolostone rocks. As water moves through these rocks it dissolves them over time, creating cracks and holes that geologists call karst. Large volumes of water can flow through the karst creating springs. An excellent example of karst springs can be seen along the Maligne River near the Jasper townsite, where large amounts of water from Medicine Lake flows through the karst to the river.
More About Springs
The flow of a spring from an aquifer reflects how the aquifer is replenished with water. If it’s replenished seasonally by precipitation or snowmelt, the spring flow will show a seasonal relationship. If the aquifer is frequently depleted of water, the amount of water flowing from the spring will drop. Springs that flow consistently all year long are likely supplied by a deeper aquifer not affected by variations in seasonal precipitation.
The water quality of springs depends on the water quality of the aquifer from which they come. As groundwater moves through an aquifer, it slowly dissolves minerals within the rock. The longer the water flows through the rocks before it emerges as a spring, the greater the amount of dissolved minerals. The measured amount of minerals dissolved in water is called total dissolved solids (or TDS) and it’s used to determine the quality of the water. Generally, higher TDS makes the water less drinkable. Springs that are directly influenced by precipitation have a short flow path and tend to have low TDS. Springs that come from deeper aquifers generally have a longer flow path and higher TDS. For example, thermal springs come from deeply buried aquifers and tend to be highly mineralized. Spring water quantity and quality can change over time, so they should always be tested for potability before drinking.
See the following table to compare the TDS in some springs in Alberta.
We frequently see mineral deposits at spring discharge sites because the spring water can contain high amounts of dissolved minerals which are dropped out of the water when exposed to the atmosphere. These mineral deposits can build up significantly over time and in some cases, they can change the landscape surrounding the discharge channel. For example, at Big Hill Springs near Airdrie, Alberta, the flowing springs created a build-up of tufa deposits. The tufa builds up in large dam-like structures which change the direction and path of the flowing spring. Once the spring flows in a different direction, the tufa deposit buildup begins again. Springs may also deposit other minerals like marl, iron, sulphur, or various salts, altering the landscape over which it flows.