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Storm ponds in Calgary

Some of Calgary’s newer communities have storm ponds to collect and hold rainfall and snowmelt before it reaches our rivers, creeks, and streams.

This runoff collects sediment and pollutants (e.g. bacteria, fertilizers, pesticides, vehicle fluids, metals, road salt) as it travels across properties, streets, and roads. By capturing and holding stormwater for a period of time, storm ponds allow sediments to settle out and provide some treatment for pollutants. The water is then slowly released to our rivers, creeks, and streams. 

Slowing the speed and reducing the sediments and pollutants helps keep our rivers, creeks, and streams healthier.

Storm Pond Odour Concerns

If you notice an odour issue, please call 311 or use the app to report your concern so crews can respond.

Types of Storm Ponds


A dry pond is dry most of the time and may have playing fields in it. During heavy rain, dry ponds will fill with water very quickly.

This prevents the stormwater system from becoming overwhelmed. This helps to prevent water from backing up into basements or flooding into houses, or businesses.

Almost all of the dry ponds have ultrasonic sensors that record water depths. The sensors also inform us when the ponds are filling with water. After a rain event, dry ponds can take up to 24 hours to drain.


Wet ponds hold water all of the time. These ponds are designed to capture and hold stormwater– for a while.

Wet ponds slow down the water, which helps settle out some of the sediments and allows some pollutants to be removed or degraded by natural environmental processes. This helps return cleaner water to our rivers, creeks, and streams.

Typically these ponds are designed to have a water depth of three metres, which can rise quickly after storms.


A wetland is a natural area of land that is saturated with water either permanently or seasonally. It contains plants and the water is quite shallow before a storm.

The plants that grow in the wetlands help remove and degrade pollutants, like fertilizers and pesticides. While many wetlands are part of the natural landscape of Calgary, some are man-made and are part of the stormwater system.

To learn more, visit Conserving Our Wetlands.

Storm ponds, both wet and dry, provide many benefits, including:

  • Storing stormwater, which can help to protect homes and businesses from possible localized flooding after a storm.
  • Slowing down the flow of stormwater during short but intense rainfalls to reduce the erosion of river and creek banks.
  • Cleaning stormwater by allowing time for sediment to settle to the bottom of the pond and for pollutants to be removed or degraded by natural environmental processes. This protects the health of our rivers, creeks and streams.
  • Providing valuable green spaces within communities for Calgarians to enjoy, including the spaces around a wet pond or the recreational areas within a dry pond. Wet ponds are not for recreational uses, such as swimming and skating.

Storm Pond Safety

Storm ponds have an important job to do. They protect the community from flooding and clean storm water. Because of rapidly changing water levels and poor water quality, a storm pond should not be used for recreational purposes like wading or skating.

No dumping

Place garbage and pet waste in bins provided or take it to one of Calgary’s landfills.

Keep your pets away from the water:

Keep your animals away from storm ponds for their health and safety.

Stay off the ice in winter:

Any type of on-ice activity, including skating, is dangerous and strictly prohibited.

Do not stock or go fishing in a storm pond:

It is illegal to stock or dump fish in a storm pond.

Stay out of the water:

Water contact (swimming, wading, boating) of any type is dangerous and strictly prohibited.

Frequently Asked Questions

There is algae growing on the pond. Is it safe?

Algae are tiny aquatic plants that grow in the shallow areas of ponds and help filter nutrients, metals, and other organic matter from the water. As they grow, they consume nutrients and trap contaminants in the pond, improving the water quality before it enters the rivers.  In most cases, algae are good for ponds. 

One form of green algae, called cladophora, is prevalent in the Calgary area. It looks like stringy, fibrous mats that can be seen floating on the water’s surface. It poses no safety concerns for humans, animals, or birds, and is a natural part of a healthy storm pond.

What causes algal blooms?

At certain times of the year, especially during warm, dry periods, storm ponds can experience excessive algal growth (blooms) which can become unsightly and at times release unpleasant odours.  

Algae blooms can be caused by a number of things: persistent warm weather, nutrients washed into storm ponds from lawn fertilizers, sediments washed into the pond, and dead or decaying vegetation. 

What is the City doing to control algal blooms?

Working with residents, community associations, and shoreline stakeholders, The City responds to numerous 311 calls through the summer months to monitor pond algae levels and odours. Please note we do not always remove the algae because they are a natural part of a healthy storm pond.

What are some of the tools and techniques used by The City to address decaying or algae blooms?

  • Floating rakes will be used to gather the algae from the pond shore. The material will be dewatered and disposed of when the bloom reaches a critical mass or it starts to decay (i.e. turn brown). Staff training is occurring in the first weeks of August. 
  • Sediment blankets (large mats that block out sunlight) have been trialed in several ponds across the City to understand their impact is disrupting the algae growth lifecycle. New techniques for easy deployment are being tested and staff training will be required.

Why do we have storm ponds in our community?

The storm ponds in your community are there to collect excess water from large storm events and help protect your property and areas downstream from flooding and riverbank erosion.

Additionally, storm ponds provide an ecological function, settling out sediment and contaminants (pesticides, animal waste, chemicals, and bacteria), from surface runoff before the water reaches the Bow River.

Why do storm ponds need vegetation around them?

Vegetation protects the banks from erosion and will help remove contaminants such as herbicides and pesticides from water before entering the pond.

Why can’t I skate on the storm pond?

Road salt and other runoff can cause the ice on storm ponds to be thinner and weaker. As well, storm pond water levels and flows can change rapidly, making skating or walking on the ice extremely dangerous.

Ice-skating and hockey must be restricted to facilities in your neighbourhood and community built for that purpose. 

Need to find a recreational hockey or skating space? Follow these links:

Why can’t I swim or wade in storm ponds?

Water entering storm ponds brings all kinds of contaminants into the ponds, including pesticides, herbicides, fertilizers, animal waste, sediment and bacteria. To prevent contact with these contaminants,, recreational activities such as swimming, boating or wading are prohibited.

Why can’t fish be placed in the storm ponds?

It is important that no fish are released into storm ponds as they can travel downstream and may harm the native species living in our rivers and creeks. The release of fish into a storm pond carries a fine of $3000 under Drainage Bylaw 37M2005.

Why can’t I cut the grass/shrubs in the green space around the storm pond?

Plants, shrubs and trees existing around storm ponds are purposely placed to help maintain the purpose and integrity of the storm ponds and to provide habitat for a variety of plant and animal species.

For example, aquatic vegetation like cattails are placed to assist in water quality management goals like nutrient reduction and protecting the banks from erosion.

Removal, cutting or pruning of any vegetation in or around the ponds can result in a fine under the Parks bylaw.

Who is responsible for maintaining the green space?

In general, Calgary Parks is responsible for green space maintenance around storm ponds. Homeowners and community associations should not be maintaining the vegetation in these areas as the requirements of green spaces around wet ponds have unique requirements.

Who is responsible for maintaining the storm pond in my community?

Water Services is responsible for the regular maintenance of storm ponds.