Rainwater or snowmelt from roofs, lawns, roadways, pavements and construction sites enters our river system carrying sediment, debris and pollutants straight into our rivers. This not only pollutes our waterways but affects the health of our streams, rivers and the land surrounding them and the health of the wildlife and fish that rely on them.
Stormwater and suspended solids
In 2005, a water quality study found that 90% of sediment – also called Total Suspended Solids (TSS) - that entered the Bow River from Calgary was from the stormwater system; 75% to 80% of the stormwater outfall system has no treatment facilities which allowed untreated water to enter directly into our waterways.
To put this in perspective, stormwater contributes approximately ten times more TSS to rivers than the outflow from our wastewater treatment plants. High levels of TSS often mean higher concentrations of bacteria, nutrients, pesticides and metals in our waterways. Learn more in ourStormwater Fact Sheet.
Stormwater management strategy
To protect the quality of water in our rivers and streams and to conserve our long-term water supply, The City developed the Stormwater Management Strategy.
One of the main goals of the Strategy is to reduce sediment entering the Bow and Elbow Rivers from our stormwater system despite the continued growth of our city.
This strategy includes constructing stormwater quality retrofit (SWQR) facilities such as wet ponds or constructed wetlands within existing developed areas across the city. Like many such facilities in newer communities, they will improve the quality of water entering our rivers by removing solids through sedimentation.
For more details, see theStormwater Management Strategy Report.