Photo: Canmenwalker · CC BY 4.0Bolton faces fewer hazards than 97% of Canadian towns
Fire has left almost no mark near Bolton: 0% of the land within 25 km since 1986, 0.000% a year. Seismic risk in Bolton sits near the middle: $0.019 of expected damage per $1,000 of buildings a year, the typical town $0.030. Radon is lower than usual: 0% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Bolton grades A+ for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Bolton’s hazards
For Bolton, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Bolton faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Bolton grades A+ for hazard risk
For Bolton, Risk will be the average of earthquakes and radon, with wildfire added only if it makes the average worse.
Its place: #10 of 866 in Ontario and #225 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.
Wildfire is rare near Bolton: 0% of the land within 25 km burned since 1986, 0% within 5 km
Past fire around Bolton’s homes, from the national burned-area record, with the fuel within 5 km.
Low: the land around Bolton burns at 0.000% a year, where the typical Canadian town sees 0.000%.
Forest fuel is spread evenly around Bolton: 14% within 5 km, 10% 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
Little or nothing burns around Bolton in a typical year; 638 of the 871 towns in Ontario share that, and Sioux Lookout leads at 0.16%.
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.
Most of the country’s 2,610 towns are low-band (92%, against 7.5% above); around Bolton, burning 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.
Bolton is on the flood map inventory: 12 studies, latest by Toronto Regional Conservation Authority
What Canada’s Flood Map Inventory lists for Bolton: who studied flooding and where to see their maps.
Toronto Regional Conservation Authority and others have studied flooding in areas that include Bolton: 12 studies, the latest from 2021.
| Study | By | Year | Status |
|---|---|---|---|
| Toronto Floodline Consolidation | Toronto Regional Conservation Authority | 2021 | final |
| Mill Creek | Credit Valley Conservation Authority | 2017 | final · not public |
| East Credit | Credit Valley Conservation Authority | 2016 | final · not public |
| Credit River | Credit Valley Conservation Authority | 2008 | final · not public |
| West Credit River | Credit Valley Conservation Authority | 2008 | final · not public |
| Credit River | Credit Valley Conservation Authority | 2007 | final · not public |
| Shaw's Creek | Credit Valley Conservation Authority | 2007 | final · not public |
| Credit River | Credit Valley Conservation Authority | 2006 | final · not public |
4 more studies on the inventory touch Bolton.
Towns with a flood study on file
Mapping in Ontario reaches 69% of towns, Bolton 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.
Studies touching Bolton run from the 1970s to the 2020s, with the most in the 2000s: 7 of 12.
Study dates as the NRCan inventory lists them, one count per study touching Bolton.
Nothing here counts toward Risk; the studies are pointers to the maps their owners keep for Bolton.
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 Bolton: $0.019 a year per $1,000
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Earthquake losses in Bolton, $0.019 per $1,000, are in line with the typical $0.030 (0.6 times).
Shaking damage a year per $1,000 of building value
Earthquake risk in Ontario peaks in Alexandria ($0.21); Bolton, at $0.019, is below the median of $0.043.
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 Bolton 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).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Bolton.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Little radon around Bolton: 0% of area homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline. · Measured across the Peel Regional Health Unit: radon tests
Fewer homes than usual test high around Bolton: 0% against 6.6% for the typical Canadian town.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Radon runs lower around Bolton than in most towns in Ontario: 0% against 4%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Under 5% puts Bolton with 37% of Canada’s 2,611 towns; 63% have more high tests.
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.
Neighbouring homes in Bolton can differ a lot; only a long-term test tells you about yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011).
Where to get warnings in Bolton
Environment and Climate Change Canada issues the weather alerts for Bolton; 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. |
In fire season, check CWFIS for danger and active fires around Bolton, and listen to local authorities for orders.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Hazards in the places around Bolton
Wildfire band, earthquake risk, radon and flood studies for each place nearby.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Bolton | Low | $0.019 | 0% | Yes |
| Wildfield 8,511 · 7.7 km | Low | $0.030 | 0% | Yes |
| Mount Royal 6,421 · 8.0 km | Low | $0.030 | 0% | Yes |
| Castlemore Estates 2,587 · 9.3 km | Low | $0.030 | 0% | Yes |
| Vales of Castlemore 14,894 · 10 km | Low | $0.030 | 0% | Yes |
| Sandalwood East (mountainash) 21,801 · 10 km | Low | $0.030 | 0% | Yes |
| Countryside 5,595 · 11 km | Low | $0.030 | 0% | Yes |
Bolton’s low band tops its neighbours; Wildfield is next (low).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Bolton faces
Practical steps for Bolton’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.
- 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. The radon share comes from about 14,000 long-term home tests in 2009–2011, pooled for now by the 2007 health region Bolton sits in.
- Flood studies aren’t flood zones. A study’s area can be a whole watershed or province, so being on the inventory says a map exists, not that a home in Bolton floods.
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Bolton’s included.
- Wildfire counts one way. Burned land within 25 km of where people live, averaged over 1986–2025 and checked for fuel near homes, is the measure; it looks back, not ahead, and only ever counts against Bolton.
Questions about flooding and hazards in Bolton
How is Bolton’s Hazard risk Grade worked out?
Hazard risk gives Bolton A+, weighing earthquakes and radon and counting wildfire only against it.
Does Bolton flood?
Bolton’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
Is Bolton at risk of wildfire?
No meaningful wildfire history near Bolton: 0% of nearby land since 1986, band low.
Is radon a problem in Bolton?
The area’s survey found 0% of 90 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Bolton.
How big is the earthquake risk in Bolton?
In NRCan’s seismic model, Bolton’s buildings lose $0.019 per $1,000 of value in an average year.
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).