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Stormwater Treatment

What is Stormwater?​

The water that enters storm drains found along streets is called stormwater. Storm drains are the drainage system that ensures water from heavy rains is diverted away from buildings. 

How is Stormwater Treated? 

Any water that enters the storm drains flows directly from Lethbridge streets into the Oldman River or into storage retention facilities called storm ponds.   


What is a Storm Pond?

The “lakes” found in your neighbourhood are not constructed to be a recreational facility; they are storm water reservoirs and their purpose is to collect and store excess storm water to prevent flooding. Storm ponds are designed with inlets for storm water to enter during high rainfall events and with outlets to slowly release excess water afterwards. Some ponds have irrigation make up water to keep them filled, this is because water from the pond is used to irrigate the park to keep it green during the summer months.

Stormwater Collection System

 The City's stormwater collection system consists of 460 kilometres of sewer, 2,000 catch basins and 26 storm water management facilities. The runoff collected by the system is discharged at 16 outfalls located along the river valley.

Stormwater Pollution

Unfortunately, there are usually other things washed into storm drains that are harmful to the river ecosystem.
To protect the Oldman River ecosystem and water quality, the City of Lethbridge has a Drainage Bylaw. The bylaw applies to everyone and regulates what can and cannot be put into the stormwater system. Protecting our fresh water resources is important as they are limited and provide life for humans and other living things.


It is important to know that:
Anything that enters street storm drains goes directly into the Oldman River untreated. In order to protect water quality, and fish and wildlife habitat, only clean water or naturally occurring stormwater should enter the drainage system.


Never allow the following to enter the storm drain system:

  • soil, sediment or other solid  matter (including yard waste)
  • gas, oil, transmission fluid, and antifreeze
  • solvents and paints
  • water from pools and hot tubs
  • industrial waste
  • soaps or detergents (including biodegradable products)
  • pesticides, herbicides, and fertilizers
  • cooking oils and grease
  • cement/concrete waste
  • sawdust and construction materials
  • any substance or combination of substances that emit odour that are washed down the storm drains will harm the river environment.


What happens if you don't comply with the Drainage Bylaw?

Failure to comply with the Drainage Bylaw can result in:  

  • fines ranging from $75 to $10,000 and/or   
  • the cost of remedial orders,
    containment and clean up.

Who should I contact to report an incident?

The Bylaw now obligates you to report and mitigate any discharge of prohibited materials whether accidental or intentional. If the release creates an immediate danger to public health and safety, call 9-1-1 for the Fire Department HAZMAT Team to respond.


For other violations and incidents, please call Lethbridge 311 (403-320-3111 if outside of Lethbridge).

DID YOU KNOW that we have been finding goldfish in our storm​ ponds?  Click here to find out more information and how you can help!




 More Information


For more information

Online: Submit a service request
Phone: 311 or 403-320-3111 (if outside of Lethbridge)
Address:  City Hall, 910 4 Avenue South, Lethbridge, Alberta, T1J 0P6