Calgary's water supply
Where does our water come from?
Our water comes from the Rocky Mountains west of the city from a basin-like landform called a watershed.
It is water collected from rain fall and snow melt which channels through creeks and streams making its way into larger rivers.
Are you a student? Find more water facts and information about Calgary's water systems at Water Education Resources.
How the City of Calgary protects our water supply
Water is a limited resource and our water supply is changing due to climate change and a growing population.
The Elbow River Watershed
The Elbow River is the source for approximately 40 per cent of Calgary's water supply. The Elbow Valley watershed covers an area of 1,227 square kilometres and drains into the Glenmore Reservoir.
It is 120 kilometres long and passes through four sub-climates before it enters the Glenmore Reservoir. The Elbow River is the source of water for the Glenmore Water Treatment Plant.
We draw water from the Glenmore Reservoir in order to provide treated water to citizens, but we also play an important role in flood control for this region.
The reservoir is maintained at a level, depending on the flow rate of the Elbow River, that minimizes the risk of flooding around the reservoir and downstream of the dam.
The Bow River Watershed
The Bow River watershed covers an area of 7,770 square kilometres.
The river originates on the Bow Glacier north of Lake Louise and is one the three main tributaries of the South Saskatchewan River.
The Bow River supplies the Bearspaw Water Treatment Plant. It is the source for nearly 60 per cent of Calgary's water supply.
How Calgary's water is processed
The Bearspaw Plant mostly supplies water to the north of the city, while the Glenmore plant supplies the south. However, water is interconnected through large diameter transmission mains to ensure a reliable supply to all times.
We withdraw water according to demand and within the rules set out by Alberta Environment. We are careful not to exceed our licenses for daily and annual withdrawals and are also careful to maintain enough flow in the river systems to support other users of the water system.
Almost all of the water that is removed from the Bow and Elbow Rivers for use in Calgary is returned to the Bow River system after treatment in Calgary's wastewater treatment plants.