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 safety
Stay Safe. Stay Off. Stay Back.
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, no recreational purposes activities like wading or skating are allowed. See the Stormwater Bylaw.
Don't release aquarium pets or other fish into storm ponds
It’s illegal to stock or release fish into a storm pond. Prussian carp and goldfish are some of the most common invasive species found in our storm ponds. These fish are not native to Alberta and with a lack of natural predators or pathogens to keep them in check, they multiply quickly. If they reach the Bow River they will alter habitats, out-compete native species for limited resources and spread disease to native species. The release of fish into a storm pond carries a fine of $3000 under Stormwater Bylaw 37M2005.
Preventing invasive species from reaching the rivers is essential. Here’s how you can help:
- Unwanted pets can be returned to the pet store or given away.
- After your pet passes on, please bury it or dispose of it in the garbage rather than flush it to prevent the spread of disease.
Have a concern about a storm pond? Please contact 311 or use the 311 app to report concerns on:
- People/animals in or on storm ponds
- Retrieval of items from storm ponds
- Algae blooms
- Inquiries or maintenance
- Fish in the pond (it is illegal to release fish into storm ponds)
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 constructed wetland is an area of land that is designed to mimic a natural wetland shape and maintain appropriate water depths so that wetland type soils and native vegetation establish within it.
The plants that grow in constructed wetlands help remove and filter pollutants, like fertilizers and pesticides.
They are typically saturated with water either permanently or seasonally. While most of the water is quite shallow before a storm, they can manage high water levels during storm events.
While some natural wetlands are part of Calgary’s landscape, some are constructed (man-made) and are part of the stormwater system. To learn more , visit Conserving Our Wetlands.
All three types of storm ponds (dry, wet, and constructed wetlands) 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, recreational activities like wading or skating are strictly prohibited under the Stormwater Bylaw.
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
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.
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.
Working with residents, community associations, and shoreline partners, 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.
- 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.
The odour is caused by the normal decay of organic matter in the pond.
In the winter as ice forms on the surface of storm ponds it can cause the water below to become lower in oxygen which also contributes to the odour. In the spring as the ice melts, the odour-producing gas is released that was trapped under the ice.
The odour is temporary and will naturally disperse once the ice on the storm pond has fully melted and mixed with the rest of the water in the pond.
While the odour is unpleasant, and potentially alarming because it may smell like natural gas, it does not pose a risk to public health or the environment at the concentrations typically found in and around storm ponds.
If you suspect a natural gas leak or the presence of other hazardous gas, we encourage you to call 9-1-1.
We take concerns about odours very seriously and thoroughly investigate them.
When an odour is reported, a Calgary fire crew attends the location to confirm that the odour is not caused by a hazardous condition such as a natural gas leak.
If the investigation indicates that the odour is entirely due to gas from the storm pond and is low in concentration, no further action is taken.
Vegetation protects the banks from erosion and will help remove contaminants such as herbicides and pesticides from water before entering the 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.
For more information on how to share the park boundary and encroachments on Parks land please visit www.calgary.ca/encroachmentparks.
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.
In general, the goal of all storm pond infrastructure is to be as zero-maintenance as possible. Water Services is responsible for the maintenance of storm ponds in Calgary.