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

Conservation Halton names Oakville among the municipalities it serves: the Bronte and Sixteen Mile Creek watersheds end in Oakville at Lake Ontario, and its smaller urban watersheds run east to Joshua's Creek. Under Ontario Regulation 41/24 its permission is needed for most work in and next to watercourses, flood plains, steep slopes, valley lands, the Lake Ontario shoreline, wetlands and other hazardous land; its online mapping shows the approximate regulated area, with staff to confirm by email, and a letter for a solicitor or realtor on a property's status costs $367 in 2026. Credit Valley Conservation lists the Town of Oakville among its member municipalities, and its regulation map viewer shows the regulated areas in the Credit River watershed; it says the viewer does not show every regulated area.

Both authorities say their permit doesn't replace the Town's building permit or other approvals. 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, Conservation Halton and Credit Valley Conservation are to join the Western Lake Ontario Regional Conservation Authority on 1 February 2027 or a later date set by regulation.

• Conservation Halton: property inquiries: the authority's online mapping of its regulated area, and how to ask for a letter on a property
• Conservation Halton: permitting: what needs the authority's permission under Ontario Regulation 41/24, by municipality
• Conservation Halton: watersheds: the Grindstone, Bronte and Sixteen Mile Creek watersheds and the smaller creeks that the authority stewards
• CVC regulation mapping: Credit Valley Conservation's map viewer of regulated areas, updated in February 2026
• CVC: who we are: the authority's member municipalities
• Conservation Halton Foundation: the authority's note that it will become part of the proposed Western Lake Ontario Conservation Authority, targeted for early 2027
• Ontario Provincial Conservation Agency: the Province's page on consolidating 36 conservation authorities into nine regional ones, not intended to take effect until early 2027
• 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
• Ontario Regulation 41/24: Prohibited Activities, Exemptions and Permits, the regulation behind every conservation authority's regulated area

Conservation-authority regulated-area and flood plain checks are not currently included in our reports, so for a Oakville home the authority's own map is 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 Oakville address.

What we cover, city by city See the sample report