Watershed Management

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What Is a Watershed?

A watershed is an area drained by a river (or creek) and its tributaries.

In the Toronto region, all watersheds are river watersheds, with the exception of the waterfront, which drains into Lake Ontario.

Toronto and Region Conservation Authority (TRCA) manages nine watersheds, working to minimize flooding and erosion and help the Greater Toronto Area adapt to a changing climate.

These benefits play an important role in keeping our environment healthy and our communities safe into the future.

You’re in a Watershed Now

Wherever you are in the Toronto region, you’re in a watershed. Use the map below to explore the Toronto region’s watersheds.

TRCA’s Role in Watershed Management

Conservation Authorities (CAs) are established and governed under the Conservation Authorities Act.

The purpose of the Act is to provide for the organization and delivery of programs and services that further the conservation, restoration, development, and management of natural resources in watersheds.

TRCA ecosystem science team members conduct water quality monitoring in the field
The role of conservation authorities includes collecting scientific data on watershed management and climate change adaptation.

Conservation authorities are not the decision-makers in land use and infrastructure planning. Municipalities implement the watershed planning requirements of provincial legislation, plans, and policies.

However, CAs play an important role by advising municipalities and infrastructure providers on matters related to natural hazards, wetlands, and drinking water source protection, and by collecting and providing scientific data on watershed management and resilience to climate change adaptation outside the plan review function.

Conservation authorities also administer a development activity permit process under section 28 of the Act for conservation authority regulated areas consisting of river and stream valleys, wetlands, watercourses, and shorelines.

Watershed Strategy

Conservation authorities are required to have several strategies and plans in place, which are under development. One of these is the Watershed-based Resource Management Strategy (“Watershed Strategy”).

TRCA’s Watershed Strategy will help us continue to protect nature and protect people from flooding and erosion in the communities we serve, and direct where to focus our conservation efforts.

We will use the latest scientific data, including climate change projections, to keep our watersheds healthy for the future.

We Want to Hear from You!

TRCA’s Watershed Strategy will be completed by the end of 2024. We welcome your ideas to help make it better. Take our survey and share your feedback by June 30, 2024.


Watershed Reporting

TRCA watershed reporting hub

TRCA’s Watershed and Ecosystems Reporting Hub enables users to interactively explore information about watersheds and the waterfront in the Toronto region.

The Hub identifies current conditions by theme and explains the importance of different environmental indicators for understanding watershed and ecosystem health.

It illustrates how conditions are changing over time and provides insights into TRCA’s progress and how this relates to our goals.

Visit TRCA’s Watershed and Ecosystems Reporting Hub to learn
what the science and data tell us about current conditions and trends
in ecosystem health across the Toronto region.


Watershed Planning

TRCA Watershed Planning Hub

TRCA also fulfills its mandate through the development and implementation of watershed plans.

Watershed planning provides a comprehensive framework, or road map, for ensuring healthy watersheds and building resilience to land use and climate changes.

Watershed plans, such as the new plan for the Humber River Watershed, now in development, offer a blueprint to help understand current and potential future watershed conditions at the watershed scale.

They also identify strategic measures and actions to protect, enhance, and restore watershed health and build resiliency.

bridge at the mouth of the Humber River
A new watershed plan for the Humber River Watershed is now in development.

Although watershed plans do not determine land use planning decisions, they do help to inform land use and infrastructure planning and other municipal initiatives, such as:

Visit TRCA’s new Watershed Planning Hub for an in-depth,
interactive exploration of watershed plans.


Updated Watershed Plans

Ecosystem Monitoring and Research

TRCA ecosystem science team member conducts terrestrial monitoring in the field

TRCA collects scientific data to understand the landscape and climate changes affecting natural areas and watercourses, and to assess the ecological health of specific regions or environmental features.

Discover the different ways we monitor our forests, wetlands, and waterways, contributing valuable data to watershed management activities.



TRCA Watershed Planning and Ecosystem Science: wpes@trca.ca