Stormwater Management

Understanding how stormwater is managed and who is responsible.

Stormwater is water from rain, snow melt, and other precipitation that runs off roofs, streets and other surfaces and drains into ditches, storm drains, local creeks and Lake Ontario.  

It is important to make sure runoff travels away from homes and buildings to protect private and public property from flooding during storms.

Managing stormwater

Rain and melted snow from your property is manage through two types of storm systems:

  • A network of smaller pipes, drains, and localized drainage structures
  • Manages stormwater runoff from smaller rainfall events or areas with lower drainage needs
  • Typically handles runoff from regular rainfalls with a shorter duration and lower intensity
  • Designed to collect runoff from individual properties, streets, parking lots, and smaller catchment areas
  • Uses smaller pipes and inlets that move the water to the major system or directly to natural water bodies, such as streams or rivers
  • Helps prevent localized flooding, ensures proper drainage in neighbourhoods, and contributes to overall stormwater management

  • Designed to handle larger and more significant storm events
  • Made up of larger pipes, channels, detention ponds, and other storage structures 
  • Capable of managing large volumes of stormwater runoff
  • Controls and moves runoff from major storms
    • Typically defined as storms with a return period of 10 to 100 years or more. (The return period of a storm is the likelihood of a storm of that size occurring within that specific time frame.)
  • Responsible for collecting stormwater from a large area, such as multiple neighbourhoods or a significant portion of the town
  • Transports the collected runoff to designated retention or detention areas, which can include large ponds, underground storage, or open channels. This is done by overland flow routes like swales and the road itself. 
  • Temporarily store the excess stormwater and release it at a controlled rate to prevent downstream flooding and reduce the impact on receiving water bodies

Oakville's stormwater infrastructure


Jurisdiction over the different types of stormwater infrastructure and natural assets is shared:

Homeowners own the pipe called the sewer lateral that connects from main sewer pipe at the property line to the home, and are responsible for lot grading around the property  

Halton Region manages sanitary sewer mains that carry wastewater/sewage from homes to treatment plants.  

Sanitary sewer mains may become submerged during overland flooding events, which can cause backups of the mainline system.

We maintain the infrastructure that helps direct runoff water underground (storm sewer pipes) and above ground (roadways, catch basins, ditches, swales, road culverts and storm ponds) within the public right-of-way.  

The town also helps maintain creeks and shorelines.

Conservation Authorities regulate the creek floodplains to help protect communities from natural hazards such as flooding.