During heavy rain, sewers can become overloaded. This increase puts pressure on the sewer systems and overland drainage routes, such as roads, local rivers and streams, which can lead to basement flooding.

In 2013, City Council approved plans to develop comprehensive plans in 67 areas across the City to reduce the risk of flooding. The study areas were determined by the underground drainage system.

For each basement flooding area, an Environmental Assessment (EA) study is conducted. These are complex studies that can take two or more years to complete.

EA studies:

  • assess the sewer and drainage system capacity
  • make recommendations to reduce the risk of flooding

Your home or property may be located in other study areas where EAs have been completed or planned for current drainage capacity assessment.

Basement Flooding Study Areas

Find out about active and completed study areas and the study area you live in.

Scope of the Study

See what's covered and not covered by the study and also answers to common questions.

Steps in the Study Process

Learn about the typical steps in the study process.

What is a Class Environmental Assessment?

Ontario’s¬†Environmental Assessment (EA) program¬†promotes good environmental planning by determining and managing the potential effects of a project prior to implementation.

The EA program ensures that public concerns are heard. EAs balances economic, social, cultural and natural environmental needs so that projects benefit Ontario.

This study is being carried out according to the Municipal Class Environmental Assessment process. This is an approved approach to satisfying requirements of the Environmental Assessment Act specifically tailored to municipal infrastructure. The process includes identifying the problem or opportunity to be addressed, developing and evaluating a range of alternative solutions, providing opportunities for public input and identifying a preferred solution.

If concerns regarding a project cannot be resolved in discussion with the City of Toronto, a person or party may request that the Minister of the Environment, Conservation and Parks (MECP) make an order for the project to comply with Part II of the Environment Assessment Act (referred to as a Part II Order), which addresses individual environmental assessments.

To submit a Part II Order request, refer to the MECP website for instructions.