Photo: David Stanley from Nanaimo, Canada · CC BY 2.0Earthquakes are Cowichan’s biggest hazard: $0.72 of damage a year per $1,000 of buildings, 24 times the norm
Wildfire is rare near Cowichan: 0.1% of the land within 25 km has burned since 1986, a burn rate of 0.003% a year. Radon is lower than usual: 0.9% of tested homes in the survey area topped the guideline, against 6.6% for the typical town. Hazard risk gives Cowichan a grade of B−; its wildfire band pulls it down.
What stands out about Cowichan’s hazards
For Cowichan, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Cowichan faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Cowichan grades B− for hazard risk
Seismic risk and radon set Cowichan’s grade, wildfire can drag it down, and flood mapping stays out of it.
How sure: Earthquake losses are a model’s expectation over many years, not a forecast for any one. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Few fires near Cowichan: 0% within 5 km, 0.1% within 25 km
Fires mapped since 1986 around where Cowichan’s residents live, and the fuel next to their homes.
Cowichan burns at 0.003% a year, low against 0.000% for the typical Canadian town.
No fire has burned within 5 km of Cowichan’s homes since 1986; the nearest burn is 5.1 km away.
There is forest near Cowichan’s homes (31% within 5 km) and more of it further out (76% 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 British Columbia · highest of 256
In the lower half in British Columbia: Cowichan at 0.003% a year, 191st of 256, far from Oliver’s 0.98%.
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.
Cowichan is in the low band with 92% of Canada’s 2,610 towns; 7.5% sit in moderate or 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.
2 flood studies cover Cowichan, the newest from Cowichan Valley Regional District
Flood studies whose area touches Cowichan, from NRCan’s inventory, each linked to its owner.
The newest of 2 studies covering Cowichan is Cowichan Valley Regional District’s, from 2009; open its map to see the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Lower Cowichan/Koksilah River Integrated Flood Management Plan | Cowichan Valley Regional District | 2009 | final |
| Cowichan and Koksilah Rivers at Duncan Floodplain Mapping | Ministry of Environment and Climate Change Strategy | 1997 | final |
Towns with a flood study on file
Cowichan is one of the 76% of towns in British Columbia with a flood study on file; across Canada it is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
The 2 studies touching Cowichan are spread over time, from the 1990s to the 2000s.
Study dates as the NRCan inventory lists them, one count per study touching Cowichan.
Flood mapping is shown for Cowichan 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 Cowichan’s costliest hazard: $0.72 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.
Roughly 23.9 times the typical $0.030: Cowichan’s $0.72 marks real seismic exposure.
Shaking damage a year per $1,000 of building value
At $0.72, Cowichan is above the typical town in British Columbia ($0.36); Duncan has the most at $1.33.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
Cowichan is in the top tenth of Canada’s 2,611 towns for earthquake risk; 0.6% rank higher.
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).
Only shaking damage to buildings in Cowichan is counted; landslides, liquefaction, tsunami and fire after a quake aren’t.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
0.9% of homes tested around Cowichan are over the radon guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
A lower share than most: 0.9% of tested homes around Cowichan, the typical Canadian town 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Radon runs lower around Cowichan than in most towns in British Columbia: 0.9% against 1.8%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
63% of Canada’s 2,611 towns have a higher share of homes over 200 Bq/m³ than Cowichan’s band, which holds 37%.
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.
Radon varies from house to house in Cowichan, so the survey is a reason to test, not a result for yours.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Data for radon tests covers the Central Vancouver Island health region
Where to get warnings in Cowichan
Alerts for Cowichan 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 Cowichan 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 Cowichan
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Cowichan | Low | $0.72 | 0.9% | Yes |
| Electoral Area E, Cowichan Valley 4,482 · 1.2 km | Low | $0.83 | 0.9% | Yes |
| Duncan 5,745 · 1.5 km | Low | $1.33 | 0.9% | Yes |
| North Cowichan 34,525 · 4.8 km | Low | $0.76 | 0.9% | Yes |
| Cowichan Bay 3,713 · 6.4 km | Low | $1.08 | 0.9% | Yes |
| Cobble Hill 5,074 · 12 km | Low | $0.68 | 0.9% | None listed |
| Shawnigan 9,903 · 13 km | Low | $0.57 | 0.9% | Yes |
The fire record around Shawnigan is a touch heavier than Cowichan’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 Cowichan faces
Practical steps for Cowichan’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 Cowichan, 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. NRCan’s inventory says where flood mapping exists, not where water goes; the map’s owner is the authority for Cowichan.
- Radon is a survey. About 14,000 homes were tested across Canada in 2009–2011, and the share over the guideline for Cowichan is its health region’s, the survey’s design unit.
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Cowichan’s census subdivision (a neighbourhood shows its city’s).
Questions about flooding and hazards in Cowichan
Is radon a problem in Cowichan?
The area’s survey found 0.9% of 109 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Cowichan.
How is Cowichan’s Hazard risk Grade worked out?
Cowichan grades B− for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
Is Cowichan at risk of wildfire?
Some, but Cowichan’s low band (0.1% of nearby land burned since 1986, latest 2022) is short of the level that counts.
Does Cowichan flood?
There is flood mapping for Cowichan on the national inventory, each study linked to its owner’s map, none of them graded.
How big is the earthquake risk in Cowichan?
About $0.72 a year per $1,000 of building value, NRCan’s long-run expectation for Cowichan.
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).