Photo: P199 · CC BY-SA 4.0Mercier is on Canada’s flood inventory: 1 listed, led by MRC Roussillon
Wildfire is rare near Mercier: 0% of the land within 25 km has burned since 1986, a burn rate of 0.000% a year. Shaking is a bigger worry than in most places, at $0.19 a year per $1,000 of building value ($0.030 typical). About as many homes carry radon around Mercier as elsewhere, 8.2% over the guideline where the typical town has 6.6%. Mercier grades C− for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Mercier’s hazards
For Mercier, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Mercier faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Mercier grades C− for hazard risk
Seismic risk and radon set Mercier’s grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #349 of 507 in Quebec and #2,317 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Few fires near Mercier: 0.1% within 5 km, 0% within 25 km
Fires mapped since 1986 around where Mercier’s residents live, and the fuel next to their homes.
The yearly burn rate around Mercier is 0.000%, low beside 0.000% for the typical Canadian town.
Around Mercier the forest is thin or far off: 0.5% of the land within 5 km and 2% within 25 km is forest fuel.
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 513
Mistissini has the highest burn rate in Quebec, 0.31% a year; around Mercier, as around 144 of the 513 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.
Like most of Canada’s 2,610 towns (92%), Mercier is in the low band, with a burn rate of zero to three decimals; 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.
Mercier is on the flood map inventory: 1 study, by MRC Roussillon
Flood studies whose area touches Mercier, from NRCan’s inventory, each linked to its owner.
For Mercier the inventory points to MRC Roussillon’s 1996 study, whose map is the one to check.
| Study | By | Year | Status |
|---|---|---|---|
| Mercier | MRC Roussillon | 1996 | final |
Towns with a flood study on file
Its flood study sets Mercier apart in Quebec, where 45% of towns have one (Canada: 58%).
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood mapping is shown for Mercier to be opened and checked, never turned into a grade.
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.
Shaking is Mercier’s costliest hazard: $0.19 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.
Mercier’s $0.19 is about 6.2 times the typical town’s $0.030: it sits in one of Canada’s more active seismic zones.
Shaking damage a year per $1,000 of building value
Above the middle in Quebec: Mercier’s $0.19 against a median of $0.14, with La Pocatière 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.
More earthquake risk than most: only 13% of Canada’s 2,611 towns are above Mercier.
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).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Mercier.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Some radon around Mercier: 8.2% of area homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline. · Shared with the rest of the Monteregie health region: radon tests
Mercier’s area sits close to the typical Canadian town: 8.2% over the guideline, against 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Mercier, 8.2% of tests topped the guideline, about the same as the typical town in Quebec (8.2%).
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Between 5% and 10% of tests over the guideline: Mercier, and 37% of Canada’s 2,611 towns; 26% are 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.
Whatever Mercier’s area share, the reading that matters is your own home’s, over a winter.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Mercier
Alerts for Mercier come from Environment and Climate Change Canada and, for emergencies, Alert Ready.
| 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. |
Fire danger and active fires near Mercier are mapped daily by the Canadian Wildland Fire Information System; evacuation orders come from the municipality or province.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Mercier
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Mercier | Low | $0.19 | 8.2% | Yes |
| Châteauguay 53,508 · 5.1 km | Low | $0.20 | 8.2% | Yes |
| Saint-Isidore 2,889 · 5.7 km | Low | $0.20 | 8.2% | Yes |
| Léry 2,817 · 6.2 km | Low | $0.16 | 8.2% | Yes |
| Sainte-Martine 5,884 · 7.6 km | Low | $0.19 | 8.2% | Yes |
| Kahnawake 11,142 · 8.7 km | Low | – | 8.2% | Yes |
| Saint-Urbain-Premier 1,380 · 10 km | Low | $0.19 | 8.2% | None listed |
The fire record around Sainte-Martine is a touch heavier than Mercier’s, but the band is the same: low (here low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Mercier faces
Practical steps for Mercier’s hazards, most pressing first.
- 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.
- Drop, cover and hold on.
- Strap the water heater down.
- Keep 72 hours of supplies.
- Has it had a radon test?
- Check the address on the flood map.
- Are flood and wildfire insured?
- Is earthquake cover included?
What this data can and can’t tell you
- Wildfire counts one way. For Mercier, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
- Flood studies aren’t flood zones. Flood studies cover areas of every size, which is why the page lists them for Mercier without grading them.
- 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 Mercier until then.
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Mercier’s census subdivision (a neighbourhood shows its city’s).
Questions about flooding and hazards in Mercier
Does Mercier flood?
A flood study covers Mercier on Canada’s Flood Map Inventory; open the owner’s map to check a street, since flood isn’t graded.
Is Mercier at risk of wildfire?
Not much by Canadian standards: Mercier’s band is low, with 0% of the land within 25 km burned since 1986 (last in 2025), so wildfire doesn’t change its grade.
How big is the earthquake risk in Mercier?
Expected earthquake damage in Mercier comes to $0.19 a year for each $1,000 that buildings are worth.
Is radon a problem in Mercier?
8.2% of the 110 homes Health Canada tested around Mercier topped the guideline; your own house needs its own test.
How is Mercier’s Hazard risk Grade worked out?
Mercier’s Hazard risk grade is C−, built on earthquakes and radon with a one-sided wildfire input.
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).