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

Conservation Halton names Milton among the municipalities it serves; the Sixteen Mile and Bronte Creek watersheds both drain parts of the town. Under Ontario Regulation 41/24 its permission is needed for most work in and next to watercourses, flood plains, steep slopes, valley lands, wetlands and other hazardous land, and its online mapping shows the approximate regulated area, with staff to confirm by email; a letter for a solicitor or realtor on a property's status costs $367 in 2026. The Grand River Conservation Authority's Map Your Property tool lists Milton among the Halton municipalities it covers, for the part of the town in the Grand River watershed. Milton's zoning by-law doesn't permit additional residential units on land a conservation authority identifies as hazard land or regulatory flood plain unless that authority permits them.

Both authorities say their permit is needed in addition to the Town's building permit, and Conservation Halton adds the Niagara Escarpment Commission's where it applies. A regulated-area result governs permits for work near water; 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 is to join the Western Lake Ontario Regional Conservation Authority, and the Grand River authority the Eastern Lake Erie 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
• GRCA Map Your Property: the Grand River Conservation Authority's map of its regulated area, with a link for Milton
• 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
• Eastern Lake Erie Regional Conservation Authority transition: the Grand River authority's page on the merger on 1 February 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 Milton 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 Milton address.

What we cover, city by city See the sample report