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

The Raisin Region Conservation Authority names the City of Cornwall among its five member municipalities, and it administers Ontario Regulation 41/24 across its jurisdiction. Its regulatory mapping page links an online portal for checking whether a location is within a regulated area, and says the mapping may still need site verification; a permit may be needed for work in a watercourse, drain, lake, pond or wetland, within 15 metres of a floodplain, slope or meander hazard, or within 30 metres of a wetland. For a buyer it offers a Property Inquiry, a formal report for a fee with maps of the regulated features on the property and any known outstanding violations. The City's zoning by-law has an Environmental Constraint Floodplain zone and sets 30-metre setbacks along the South Branch of the Raisin River, subject to the authority's review.

The authority says its permit does not override any other permit requirement, federal, provincial or municipal, and that its permit must be obtained before the municipality issues a building permit, because the Conservation Authorities Act is applicable law under the Building Code. A regulated-area result governs permits; 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 Raisin Region authority is to join the St. Lawrence River Regional Conservation Authority on 1 February 2027 or a later date set by regulation.

• RRCA: regulatory mapping: the authority's online mapping portal and what may need a permit
• RRCA: property inquiries: the formal property report for buyers, lawyers and agents
• RRCA: permitting FAQs: its permit and the municipality's building permit
• RRCA: about: the five member municipalities, the City of Cornwall among them
• Zoning By-law 2022-001, December 2025 office consolidation: section 3.13, lands subject to flooding, and the floodplain zone (PDF)
• 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 Cornwall 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 Cornwall address.

What we cover, city by city See the sample report