Photo: Ymblanter · CC BY-SA 4.0Radon is Grande-Vallée’s main hazard: 25% of tested homes in its area top Health Canada’s guideline
For Grande-Vallée, wildfire history is close to nil: 0% of nearby land since 1986, 0.000% a year. For earthquakes Grande-Vallée is middling, $0.021 a year per $1,000 against $0.030 for the typical town. Hazard risk gives Grande-Vallée a grade of C, from earthquakes and radon alone.
What stands out about Grande-Vallée’s hazards
Four national sources, each read for Grande-Vallée: earthquakes, radon, past fires and flood studies.
What Grande-Vallée faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Grande-Vallée grades C for hazard risk
Two inputs always count for Grande-Vallée, earthquakes and radon; the third, wildfire, counts only against a town.
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.
Few fires near Grande-Vallée: 0% within 5 km, 0% within 25 km
Fires mapped since 1986 around where Grande-Vallée’s residents live, and the fuel next to their homes.
At 0.000% of the land a year, Grande-Vallée’s burn rate is in the low band; the typical Canadian town sees 0.000%.
Since 1986 the nearest fire to Grande-Vallée’s homes came within 11 km, never inside 5 km.
Forest fuel is spread evenly around Grande-Vallée: 88% within 5 km, 93% 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 Quebec · highest of 514
Mistissini has the highest burn rate in Quebec, 0.31% a year; around Grande-Vallée, as around 145 of the 514 towns, it rounds to 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.
Measured against 2,610 towns, Grande-Vallée is in the largest group, low (92%), and at its floor, while 7.5% rank higher.
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.
Grande-Vallée is on the flood map inventory: 1 study, by Gouvernement du Québec
Flood studies whose area touches Grande-Vallée, from NRCan’s inventory, each linked to its owner.
A 2006 study by Gouvernement du Québec covers Grande-Vallée, and its map, not the inventory, shows the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Grande-Vallée | Gouvernement du Québec | 2006 | final |
Towns with a flood study on file
Only 45% of towns in Quebec have a flood study, short of Canada’s 58%; Grande-Vallée is one of them.
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 Grande-Vallée’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 Grande-Vallée: $0.021 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.
0.7 times the typical $0.030: Grande-Vallée’s $0.021 is ordinary.
Shaking damage a year per $1,000 of building value
At $0.021, Grande-Vallée is below the typical town in Quebec ($0.14); La Pocatière is highest at $0.48.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Around half of Canada’s 2,611 towns expect more shaking damage than Grande-Vallée (63%).
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 loss is to Grande-Vallée’s buildings alone, from ground shaking; infrastructure and secondary hazards are left out.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Radon runs high around Grande-Vallée: 25% of tested homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Grande-Vallée’s survey area reads 25% over the guideline, well past the typical Canadian town’s 6.6%. Grande-Vallée doesn’t get its own radon tests figures; the ones here come from the Gaspesie - Iles-de-la-Madeleine health region.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Grande-Vallée’s area, at 25%, is above the median in Quebec (8.2%), and 3.4% of its tests passed 600 Bq/m³.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Few of Canada’s 2,611 towns (3.1%) share the 20–30% band with Grande-Vallée, and 1.5% sit above it.
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.
Basements, soil and how a house is sealed decide its radon, so in Grande-Vallée only a test can say.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Weather and fire alerts for Grande-Vallée
Environment and Climate Change Canada issues the weather alerts for Grande-Vallée; 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 Grande-Vallée come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Get ready for what Grande-Vallée faces
What to do about the hazards Grande-Vallée 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 Grande-Vallée until then.
- Earthquakes are modelled. NRCan models what earthquakes would cost buildings each year on average, subdivision by subdivision; Grande-Vallée’s figure is its subdivision’s.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Grande-Vallée without grading them.
- Wildfire counts one way. Wildfire is read from the national burned-area record around Grande-Vallée’s homes since 1986, a history of fire that may lower Risk but never raises it.
Questions about flooding and hazards in Grande-Vallée
Is radon a problem in Grande-Vallée?
Around Grande-Vallée, 174 survey homes were tested and 25% came in over 200 Bq/m³, a guide to the area, not to any one home.
Does Grande-Vallée flood?
A flood study covers Grande-Vallée on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
Is Grande-Vallée at risk of wildfire?
Fire has reached 0% of the land around Grande-Vallée since 1986 (last in 2013); at low, it neither helps nor hurts the grade.
How big is the earthquake risk in Grande-Vallée?
About $0.021 a year per $1,000 of building value, NRCan’s long-run expectation for Grande-Vallée.
How is Grande-Vallée’s Hazard risk Grade worked out?
Grande-Vallée grades C for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the 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).