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Storm ponds in Calgary

Storm Pond Image

When it rains and snow melts, water flows from our rooftops, driveways, lawns, streets and sidewalks. This stormwater empties into storm drains where pipes carry it to storm ponds.

Storm ponds work like naturally occurring ponds and wetlands. They move run-off from streets and away from homes and businesses. They slow the water down to relieve pressure on the stormwater system and improve the water's quality before it moves to streams and rivers.

Storm ponds also protect our rivers by removing sediment, fertilizer, pesticides and other pollutants. They also prevent flooding by controlling the release of extra stormwater.

How does The City manage stormwater?

Storm ponds are one way that we manage stormwater. Some of the stormwater is diverted from our drainage system and collected in storm ponds.

Once the water is collected, it has time to rest which helps to remove pollutants and sediment then the stormwater is released slowly, at a rate that prevents flooding and erosion, into the Bow and Elbow Rivers.

Why do some storm ponds give off a smell at certain times of the year?

Calgarians have around 200 storm ponds and 800 km of piping between sanitary and storm. Odour issues will affect a variety of ponds in Calgary at different times of the year. In fact, Calgary’s thaw history hasn’t shown this to be a repeatable problem in any one area.

We do know that weather variation, vegetation, cross connections, and other factors can lead to odour. We also know that spring melt is a trigger for odour issues in our ponds because as warmer temperatures kick start the biological processes under the water in a pond, gases are created. These gases need somewhere to go and find their way through piping and other channels.

What is The City doing to help with the situation

If you notice an odour issue in your neighbourhood, please call 311 or use the 311 app to register an odour service request.

Water crews respond to 311 storm pond odour concerns. They work to vent areas of the storm collection infrastructure which help reduce the odour. Crews monitor H2S levels at all storm ponds across the city.

What is an H2S reading?

Hydrogen sulfide is produced naturally from decaying organic matter. This is the odour that residents may notice. An H2S reading of 0.01 – 1.5 indicates that a rotten egg smell is noticeable.

Humans can smell H2S gas at very low concentrations. Although the smell is noticeable, health and safety of residents is not at risk.

What is The City’s long term plan to manage storm ponds?

The City has a storm pond assessment program. The program began in 2015 - we assess and collect data on storm ponds. We use the information gathered in decisions related to storm pond design, operation, renewal and maintenance, including odour management.

Tips for your local storm pond

Our storm ponds are all work and no play - they have an important job to do. Because of changing water levels and poor water quality, they are not for recreation.

  • Stay out of the water
  • Keep your pets away from the water
  • Stay off the ice
  • Do not add fish to a storm pond
  • Do not go fishing in a storm pond
  • Do not dump garbage in a storm pond
  • Dispose of hazardous waste properly

For more information, see our "What is a Storm Pond?" brochure, and our Storm Drainage System and Storm Drainage FAQ pages.​