The official website of the City of London300 Dufferin Avenue519-661-CITY (2489)3-1-1 (within London)

Stormwater Management Facilities

Stormwater Management Facilities
The name is quite a mouthful, but stormwater management facilities have a simple purpose: they gather rainfall and surface water runoff to help reduce the possibility of flooding and property damage. Through a combination of landscape and structural features, stormwater management facilities slow and filter stormwater runoff after a rainfall. The water that accumulates in stormwater ponds and wetlands is released gradually back into the natural watercourses which helps to avoid erosion of the watercourse and downstream flooding.

In addition, the stormwater ponds and wetlands are an attractive feature. In many neighbourhoods stormwater management facilities are surrounded by natural vegetation and provide habitat for birds and animals.

Stormwater ponds and wetlands differ from natural ponds and wetlands in being that they are man-made. They are specifically designed to collect runoff from streets, the ground surface and storm sewers.

As of 2008, the City of London has approximately 100 stormwater management (SWM) systems constructed within the City’s boundaries.  The Engineering and Environmental Services Department (EESD) anticipates that future development and capital work allocations will lead to the construction of an additional 118 SWM facilities over the next 10-20 years.   The total estimated cost for existing and proposed storm drainage and SWM infrastructures represents approximately $600 million.

Design of SWM facilities are also based on the MOE’s “Stormwater Management Planning and Design Manual”.  These documents are developed in accordance with Provincial and Federal Acts to ensure that each SWM facility will function to protect the public and property and meet the necessary environmental targets.

There are eight types of SWM systems constructed within the City of London boundaries:

  1. Wet ponds
  2. Dry ponds
  3. Energy dissipation systems
  4. Surface storage areas
  5. Wetlands
  6. Detention/retention channels
  7. Oversized pipes
  8. Oil-grit separators

The majority of new regional SWM systems in London are represented by wet ponds.  However, the City’s SWM infrastructure constructed in the 1980s and the early 1990s include a number of surface storage areas, dry ponds, channels, oversized pipes, and oil/grit separators.

How does the storm sewer system impact water quality?

The storm sewer system takes water from our roads and properties to a stormwater management facility for treatment or directly to an open watercourse, such as the Thames River.  We must be conscious of the quality of the water in the storm sewer system since what we put down the storm drain may end up in a natural watercourse.  

Our goal is to ensure that the water entering our natural heritage systems is clean  and can help sustain or improve that existing natural heritage conditions.

We can all help out by taking the following actions:


  • Do not pour anything down the road drain that you would not want to put directly into a river or stream!   
  • Harmful liquids should be disposed of as (Household Special Waste
  • Use eco-friendly cleansers to wash your car.
  • Limit the use of pesticides on your lawn.
  • Ensure your vehicle is not leaking oil.
  • Pick up animal wastes.
  • Look for signs of other contaminants that may end up leaking into the storm sewer.

The Stormwater Engineering Division along with all the strategic partnerships with Local Ministries, Community Active Groups and internal Departments and Divisions feel that through active dialog and a system approach to planning, engineering and design of Stormwater Management Facilities, helps to identify, protect and preserve key natural heritage features and characteristics within the City of London for the future.