Ontario flood map lookups often involve more than one source because floodplain mapping is commonly created by municipalities and conservation authorities.
Last checked: June 2, 2026
Quick answer
Start with Ontario’s flood mapping information, then find the conservation authority or municipality for the address and check local floodplain maps, regulation limits, and planning rules.
What to verify
| Check | Why it matters | Official place to verify |
|---|---|---|
| Conservation authority | Many Ontario flood maps are watershed-based. | Local conservation authority |
| Municipality | Planning and zoning rules may use local flood data. | City or town planning office |
| Map date | Flood maps can be old or under update. | Map legend or metadata |
| Regulated area | Permit requirements may apply near hazards. | Conservation authority regulation map |
| Property-specific interpretation | Boundaries can be unclear near lots. | Local office or professional survey |
Step-by-step check
- Open Ontario’s flood hazard identification and mapping page.
- Identify the municipality and conservation authority for the address.
- Search the conservation authority map or regulated-area viewer.
- Check municipal zoning, official plan, or planning map layers if available.
- Record map date, layer name, and any disclaimers.
- Contact the authority before buying, building, or applying for permits near a mapped hazard.
Red flags or common mistakes
- Using only a national flood inventory for a local decision.
- Ignoring conservation authority regulated-area maps.
- Assuming old maps reflect current development rules.
- Skipping local confirmation before renovation or purchase.
Official sources to check
Use official government, regulator, utility, or program pages before relying on private directories, ads, or contractor claims.
- Ontario flood hazard identification and mapping
- Ontario floods information
- Ontario conservation authorities
- Natural Resources Canada flood mapping resources
FAQ
Who makes Ontario flood maps?
Ontario notes that many flood maps are created by municipalities and conservation authorities.
Can I build in a mapped floodplain?
That depends on local planning, conservation authority, and permit rules. Check official local sources.
Are conservation authority maps official?
They are important official local sources, but use the specific authority for your watershed.
Related checks
Note: Home Public Check is not a government agency, licensing board, utility, insurer, tax adviser, or legal adviser. This guide explains how to find and read official sources. Rules, eligibility, records, fees, and portals can change by location and date.