Does a Toronto ravine lot need TRCA approval?

Yes, most work on or near a Toronto ravine lot will require approval from the Toronto and Region Conservation Authority (TRCA) before you can proceed — and in many cases, this is required in addition to a City of Toronto building permit.

The TRCA regulates development within its jurisdiction under the Conservation Authorities Act (Ontario). If your property is within or adjacent to a regulated area — which includes river valleys, ravines, floodplains, wetlands, and their associated hazard lands — you'll need a Section 28 permit (also called a "Permit to Alter a Watercourse or Shoreline" or more broadly a "Development, Interference with Wetlands and Alterations to Shorelines and Watercourses" permit) before breaking ground on most projects.

What Triggers TRCA Review?

Almost any physical change to the property can trigger TRCA oversight if you're in a regulated area. This includes building additions, new structures, decks, retaining walls, grading, landscaping, tree removal, and even some drainage work. The regulated boundary typically extends 10 metres beyond the stable top of bank of a ravine or valley, though this varies by site. If you're unsure whether your property falls within the regulated area, the TRCA's online mapping tool (trca.ca) lets you check your address.

It's worth noting that Toronto's Ravine and Natural Feature Protection (RNFP) Bylaw adds another layer of regulation on top of TRCA rules. Under this bylaw, you generally cannot injure, destroy, or remove any tree or vegetation within a regulated ravine area without City approval. This applies even to trees on private property within the ravine protection overlay.

Timelines and Costs

TRCA permit applications typically take 6 to 16 weeks depending on complexity, and some projects require a formal Environmental Impact Study (EIS) prepared by a qualified environmental professional — which can add $3,000–$10,000+ to your pre-construction costs. Simple applications (like a small deck set well back from the valley) move faster than projects involving grading or structures near the slope.

City of Toronto building permits are processed separately through toronto.ca/building, so you may be navigating two approval processes simultaneously. Many homeowners on ravine lots find it helpful to hire a planning consultant or landscape architect familiar with both TRCA and City requirements to manage the process.

Professional Guidance

This is not a DIY-approval situation. Attempting work without TRCA approval on a regulated lot can result in stop-work orders, mandatory restoration at your expense, and significant fines. Before doing anything — even seemingly minor landscaping — contact the TRCA directly at 416-661-6600 or submit an inquiry through trca.ca to confirm whether your specific project requires a permit.

Your next step is to identify your property's regulated status using the TRCA mapping tool, then consult with a contractor or planning professional experienced with ravine properties. You can find contractors familiar with Toronto's unique ravine lot requirements by browsing the Toronto Construction Network directory.