Is a Mississauga address in a regulated flood area, and whose map says so?

Three conservation authorities share Mississauga. Credit Valley Conservation covers the Credit River watershed and publishes a regulation map viewer, updated by its board on 20 February 2026, and a floodplain map viewer. The Toronto and Region Conservation Authority covers the Etobicoke Creek and Mimico Creek watersheds, among others, and its own table puts 33% of Mississauga's population inside its jurisdiction; its Regulated Area Search takes an address or postal code. Conservation Halton says Sixteen Mile Creek and several smaller watersheds drain parts of Mississauga, and it offers online mapping and written property inquiries.

Which authority a lot falls to follows the watershed, not the street, so the first step is the right map. A regulated-area result governs permits for work near water, such as additions, decks and grading; it is not a forecast that a home will flood, and a home outside the mapped area can still take water through a basement. Under the Conservation Authorities Act as amended in 2026, Credit Valley Conservation and Conservation Halton are to join the Western Lake Ontario Regional Conservation Authority, and the Toronto and Region authority the Central Lake Ontario Regional Conservation Authority, on 1 February 2027 or a later date set by regulation.

• CVC regulation mapping: Credit Valley Conservation's regulation and floodplain map viewers
• TRCA Regulated Area Search: the address search for the Toronto and Region Conservation Authority's regulated area
• About TRCA: jurisdiction: the authority's watersheds and the share of each municipality's population inside them
• Conservation Halton property inquiries: the authority's online regulation mapping and written inquiries
• Conservation Halton watersheds: the watersheds that drain parts of Mississauga
• Ontario Regulation 41/24: the regulation behind every conservation authority's regulated area
• Bill 97, Plan to Protect Ontario Act (Budget Measures), 2026: Schedule 3 amends the Conservation Authorities Act; the transition date is 1 February 2027 or a later date set by regulation
• Regional conservation authority boundaries (ERO 025-1257): the Province's decision of 10 March 2026 on which authority joins which of the nine regional authorities

Conservation-authority regulated-area and flood plain checks are not currently included in our reports, so for a Mississauga home the authorities' own maps are the place to look. The full report's water and flooding group does cover past floods seen by satellite, nearby creeks, rivers and ponds, and mapped wetlands for any Mississauga address.

What we cover, city by city See the sample report