TRCA Flood Plain Map

Introduction to the Flood Plain Map Viewer:
What You Need to Know About Flood Plain Management


Flood plain management is a fundamental objective of Toronto and Region Conservation Authority (TRCA). A key tool used to meet this objective is the land-use planning framework and associated policies that regulate development within the flood plain.

DEFINITION: What is a flood plain?

Knowing the extent of the flood plain is an important tool for both land use planning and emergency management.

TRCA undertakes flood plain mapping under the responsibility given to it under the Conservation Authorities Act and its section 28 Regulation: Ontario Regulation 166/06.

Flood plain management helps to:

  • Guide sensitive land use away from high-risk areas
  • Identify ways to mitigate flood risk where historical development has already occurred
  • Protect people, property, and the resilience of our urban areas
aerial view of Bolton Berm following major maintenance work in 2021
Flood plain management helps TRCA guide sensitive land use away from high-risk areas and identify ways to mitigate flood risk in areas where development has already happened.

About Flood Plain Mapping

Flood plain mapping studies are technical assessments that use local information from each watershed in order to determine the extent of the flood plain.

Flood plain mapping studies are prepared and approved for TRCA by qualified engineers, using standards and criteria established by the Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry.

Flood plain mapping studies use topographical information, surveys of infrastructure (such as the size of bridges and culverts), land use and land cover information, weather, and stream flow data to create detailed hydraulic and hydrologic models of each watershed.

Within TRCA’s jurisdiction it is standard practice to complete comprehensive flood plain mapping updates on a 10 year cycle. This ensures that flood plan maps and associated hydrology and hydraulic modelling incorporate latest land use and land cover information, as well as technological advancements in modelling software and techniques so that the resulting flood plain maps remain current and state of the art.

Watercourses and the associated regulated flood plain are just one of the natural features and hazards that are components of TRCA’s regulation limit.

You may still be in a TRCA regulated area —even if
you’re outside the flood plain.

To learn more about the rules and regulations regarding development within TRCA’s regulation areas — particularly within a flood regulated area — please visit our Planning and Permits section.

TRCA’s Regulated Area Search Tool can help you find out if your property is located within our regulated area. Select the thumbnail below to go to the search tool now.

TRCA regulated area search tool

Using the Flood Plain Map Viewer

TRCA’s Flood Plain Map Viewer presents a digital representation of the current flood plain mapping data and allows users to explore TRCA’s jurisdiction to see the flood plain in a particular area.

To pan and zoom to a location using the map viewer:

  1. Review the disclaimer pop-up and select “I agree”.
  2. When the map opens, use the search tool at the top of the map.
  3. Type your address into the box and hit the enter key to locate the address.
  4. Zoom in or out using the + and – buttons.
  5. Locations within the shaded blue areas are in the flood plain, and could be at risk of riverine flooding.
  6. What does it mean if my property is within the regulatory flood plain?

PLEASE NOTE: The map viewer depicts riverine flood plain extents only. It does not refer to flooding caused by local drainage capacity constraints (urban flooding).




The information on this website does not constitute a regulatory flood plain map as formally approved by a qualified Professional Engineer and TRCA. This viewer depicts a generalized representation of the regulatory flood plain and should not be relied upon for the precise limits of the regulatory flood plain. For confirmation of the precise flood plain limit and/or to obtain a copy of an up-to-date regulation flood plain map, please contact TRCA.

Toronto and Region Conservation Authority does not warrant that the data is complete or current. Toronto and Region Conservation Authority may make changes to the data at any time without notice. Toronto and Region Conservation Authority does not, however, make any commitment to update the data.

The availability of the data from this flood plain viewer (“Data”) does not constitute a scientific publication, ownership or intellectual property rights. The TRCA and its suppliers and distributors do not guarantee the quality, accuracy or completeness of any Data provided to any user of the Data (the “Recipient”). Thus, to the extent permitted by law, TRCA excludes all warranties.

The Data and its use is provided “As is” without warranty of any kind, including, without limitation, the warranties of merchantability, fitness for a particular purpose, identity or ownership of data or information, or that the use of such data or information will not infringe any patent, intellectual property, or proprietary rights of any party.

In no event shall Toronto and Region Conservation Authority be liable for any damages, losses or claims (including, without limitation, damages for loss of data or profit, or due to business interruption,) arising out of the use or inability to use this data.

In accordance with scientific standards, appropriate acknowledgement of TRCA should be made in any publications or other disclosures concerning the Data.

Toronto and Region Conservation Authority may revise these terms of use for its data at any time without notice. By using this data, you are agreeing to be bound by the then current version of these Terms and Conditions of Use.