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

Hamilton's zoning carries no flood plain overlay of the Ottawa kind; the record is the conservation authority's. The Hamilton Conservation Authority covers most of the city and publishes a regulated area map tool for a property, with staff to confirm by email or phone. Its regulated area takes in rivers, creeks and their flood plains, wetlands, ravines and valleys, parts of the Escarpment, steep slopes, the Dundas Valley and the Harbour and Lake Ontario shoreline, with adjacent lands. The City's own correspondence names four authorities in Hamilton: the Hamilton, Grand River and Niagara Peninsula authorities and Conservation Halton, so a home in Flamborough, Waterdown or eastern Stoney Creek may fall to one of the other three.

The authority's page says a lot near these features is probably affected, and that its permit is separate from a building permit. A regulated-area result governs permits for grading, filling, building and 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, the Hamilton authority, the Niagara Peninsula authority 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.

• HCA regulated area map tool: map a property against the Hamilton Conservation Authority's regulated area
• HCA regulation and permits: what the regulated area covers and how to ask staff
• 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 Hamilton home the authority's own map tool 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 Hamilton address.

What we cover, city by city See the sample report