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

Three conservation authorities share Halton Hills, and the Town's zoning page links a map of their regulated areas. Credit Valley Conservation, which lists Halton Hills among the member municipalities that fund it, covers the Credit River watershed and publishes a regulation map viewer, updated by its board on February 20, 2026, and a floodplain map viewer. Conservation Halton says Sixteen Mile Creek drains parts of Halton Hills, and it offers online regulation mapping and written property inquiries. The Grand River Conservation Authority's Map Your Property tool lists Halton Hills among its municipalities: look up the address and see whether it falls within the 'Regulation Limit (GRCA)' layer.

Conservation Halton and the Grand River authority both say their permission doesn't replace the Town's building permit or other approvals, and Conservation Halton names the Niagara Escarpment Commission among the other agencies. 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, Credit Valley Conservation and Conservation Halton are 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 Authorities Regulated Area: the Town's map of the Credit Valley, Conservation Halton and Grand River regulated areas, linked from its zoning page (PDF)
• CVC regulation mapping: Credit Valley Conservation's regulation and floodplain map viewers, updated February 20, 2026
• Credit Valley Conservation: who we are: the authority and the member municipalities that fund it
• Conservation Halton property inquiries: the authority's online regulation mapping and written inquiries
• Conservation Halton watersheds: Sixteen Mile Creek and the parts of Halton Hills it drains
• Conservation Halton permitting: what its permission covers, and that it doesn't replace other permits
• GRCA Map Your Property: the Grand River Conservation Authority's map of its regulated area, by municipality
• GRCA permits: what needs a permit in a regulated area, and that it doesn't replace local permits
• Conservation Halton Board meeting, June 18, 2026: the board report on the Western Lake Ontario Regional Conservation Authority transition, with Credit Valley, Hamilton and Niagara Peninsula (PDF)
• Eastern Lake Erie Regional Conservation Authority transition: the Grand River authority's page on the merger planned for February 1, 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 Halton Hills 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 Halton Hills address.

What we cover, city by city See the sample report