Photo: Dan MacNeal · CC BY 4.0A flood study covers Grand Valley: 1 on the national inventory, the newest from Grand River Conservation Authority
Fire has left almost no mark near Grand Valley: 0% of the land within 25 km since 1986, 0.000% a year. Shaking is about as much of a worry in Grand Valley as in most places, at $0.019 a year per $1,000 of building value ($0.030 typical). Radon is higher than usual: 11% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Grand Valley grades B− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Grand Valley’s hazards
Four national sources, each read for Grand Valley: earthquakes, radon, past fires and flood studies.
What Grand Valley faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Hazard risk in Grand Valley: B−
Risk averages earthquakes and radon; wildfire joins only where it pulls the average down, so a town like Grand Valley with little fire nearby would get no credit for it.
Its place: #650 of 866 in Ontario and #1,585 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. Small fires and grass fires are largely missing from the national burned-area record.
Wildfire is rare near Grand Valley: 0% of the land within 25 km burned since 1986, 0% within 5 km
Fires mapped since 1986 around where Grand Valley’s residents live, and the fuel next to their homes.
Low by Canadian standards: 0.000% of the land a year around Grand Valley, 0.000% for the typical Canadian town.
11% of the land within 5 km of Grand Valley is forest fuel, close to the 12% within 25 km.
Shares of land within 5 and 25 km of populated blocks: burned at least once in 1986–2025 (CWFIS burned-area composite), forest fuel and grass (fire behaviour fuel types, 2026, 250 m grid).
Burn rate a year, towns in Ontario · highest of 871
Among the 871 towns in Ontario, Sioux Lookout burns fastest (0.16% a year); Grand Valley is with the 638 near zero.
Each bar: the yearly average share of land within 25 km of a town’s homes that burned, 1986–2025 (CWFIS); the seven highest towns of 2,500 people or more.
92% of Canada’s 2,610 towns are in the low band and 7.5% above it; Grand Valley is among the many where the yearly burn rate rounds to zero.
Bands of the yearly burn rate: low under 0.05%, moderate under 0.25%, high under 1%, very high 1% or more; towns of 2,500 people or more.
Fire danger and active fires (CWFIS)
Canadian Wildland Fire Information System: National Burned Area Composite 1986–2025 and fire behaviour fuel types (2026), Natural Resources Canada. Measured within 25 km and 5 km of each populated dissemination area; past fire, not a forecast.
A flood study covers Grand Valley, from Grand River Conservation Authority: 1 on the inventory
Flood studies whose area touches Grand Valley, from NRCan’s inventory, each linked to its owner.
A 2018 study by Grand River Conservation Authority covers Grand Valley, and its map, not the inventory, shows the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Grand River Regulatory Floodplain | Grand River Conservation Authority | 2018 | final |
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, Grand Valley included, beside 58% across Canada.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood is shown here, never graded: a study says where a map exists, not how many of Grand Valley’s homes stand in a flood zone.
The inventory’s own caution (NRCan): “The Canada Flood Map (CFM) does not include every flood hazard map in Canada and may be incomplete or contain inaccuracies. It should not be relied upon as the official source of flood mapping information. Furthermore, if a map appears to be missing, this does not necessarily mean that the area has never been mapped. For the official version of a map, updated information, or confirmation of applicable regulations, please contact the local authority responsible for flood mapping.”
Natural Resources Canada, Canada Flood Map Inventory; links go to each study’s owner.
Expected shaking damage in Grand Valley: $0.019 a year per $1,000
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
At $0.019 per $1,000, Grand Valley’s earthquake risk is about the typical Canadian town’s ($0.030; 0.6 times).
Shaking damage a year per $1,000 of building value
The typical town in Ontario expects $0.043 a year in shaking damage; Grand Valley expects less, $0.019, and Alexandria the most, $0.21.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Earthquakes cost less around Grand Valley than in 66% of Canada’s 2,611 towns.
Each column: the share of Canada’s towns of 2,500 people or more in that range of yearly loss per $1,000 (NRCan, 2022).
The model counts damage to Grand Valley’s buildings and their occupants from shaking only: not liquefaction, landslides, tsunami or fires after a quake.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
11% of homes tested around Grand Valley are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Grand Valley’s survey area reads 11% over the guideline, well past the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
More homes top the guideline around Grand Valley (11%) than in the typical town in Ontario (4%); 2% went over 600.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
One test in ten or more tops the guideline around Grand Valley, as in 22% of Canada’s 2,611 towns; 4.6% go higher.
Each bar: the share of Canada’s towns of 2,500 people or more whose survey area had that share of tests over 200 Bq/m³.
The survey sampled homes around Grand Valley; it can’t tell you your basement’s level.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Radon tests: one figure for all of the Wellington-Dufferin-Guelph Health Unit
Weather and fire alerts for Grand Valley
Environment and Climate Change Canada issues the weather alerts for Grand Valley; Alert Ready carries the urgent ones to phones, radio and TV.
| Alert | What it means |
|---|---|
| Warning | Severe weather is happening or about to: act now. |
| Watch | Conditions favour severe weather: be ready. |
| Advisory | Weather that is less severe but could disrupt the day. |
| Special weather statement | Unusual weather worth knowing about. |
| Special air quality statement | Poor air, often wildfire smoke. |
Smoke and fire warnings for Grand Valley come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Grand Valley
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Grand Valley | Low | $0.019 | 11% | Yes |
| East Garafraxa 2,976 · 10.0 km | Low | $0.018 | 11% | Yes |
| Amaranth 4,808 · 14 km | Low | $0.019 | 11% | Yes |
| Orangeville 33,070 · 17 km | Low | $0.012 | 11% | Yes |
Among its neighbours Grand Valley has the most fire on record (low); East Garafraxa follows (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Grand Valley faces
What to do about the hazards Grand Valley faces, and what to ask before you buy.
- Test for three months in winter.
- Over 200 Bq/m³: fix it.
- Kits are cheap; pros test too.
- Never drive through floodwater.
- Move papers and medicines upstairs.
- Ask whether your street is mapped.
- Clear needles and wood nearby.
- Keep a grab-and-go bag ready.
- In smoke, stay in; filter air.
- Has it had a radon test?
- Check the address on the flood map.
- Are flood and wildfire insured?
What this data can and can’t tell you
- Radon is a survey. Radon figures pool the survey’s home tests by area: postal areas once their boundaries arrive, the 2007 health region around Grand Valley until then.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Grand Valley without grading them.
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Grand Valley’s figure is its subdivision’s.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Grand Valley’s homes since 1986, a history of fire that may lower Risk but never raises it.
Questions about flooding and hazards in Grand Valley
How is Grand Valley’s Hazard risk Grade worked out?
Hazard risk gives Grand Valley B−, weighing earthquakes and radon and counting wildfire only against it.
How big is the earthquake risk in Grand Valley?
About $0.019 a year per $1,000 of building value, NRCan’s long-run expectation for Grand Valley.
Is radon a problem in Grand Valley?
Around Grand Valley, 99 survey homes were tested and 11% came in over 200 Bq/m³, a guide to the area, not to any one home.
Does Grand Valley flood?
A flood study covers Grand Valley on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
Is Grand Valley at risk of wildfire?
Very little by the national record: Grand Valley’s band is low, with 0% of the land within 25 km burned since 1986, so wildfire doesn’t change its grade.
Seismic risk: Natural Resources Canada. Radon: Health Canada. Wildfire: Canadian Wildland Fire Information System. Flood studies: Natural Resources Canada, Canada Flood Map Inventory. Contains information licensed under the Open Government Licence – Canada.
Sources: NRCan, Canada’s Seismic Risk Model 2022 · Health Canada, Cross-Canada Survey of Radon Concentrations in Homes · CWFIS, National Burned Area Composite and FBP fuel types · NRCan, Canada Flood Map Inventory. Under the Statistics Canada Open Licence.
Adapted from Statistics Canada (Census of Population 2021, population estimates 2025, 2021 census boundaries) under the Statistics Canada Open Licence; this does not constitute an endorsement by Statistics Canada. Neighbourhood names in some cities © OpenStreetMap contributors (ODbL).