Photo: UBC Micrometeorology · CC BY 2.0Earthquake risk in Delta runs 20 times the typical Canadian town’s: $0.60 per $1,000 a year
Burn scars are few around Delta, with 0.1% of the land within 25 km touched by fire since 1986 (0.003% a year). Fewer homes than usual carry radon here, 0% over the guideline where the typical town has 6.6%. Hazard risk gives Delta a grade of B−; its wildfire band pulls it down.
What stands out about Delta’s hazards
For Delta, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Delta faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Delta grades B− for hazard risk
Seismic risk and radon set Delta’s grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #95 of 254 in British Columbia and #1,571 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. The radon share rests on 70 home tests in the survey area, so a few homes move it. The burned-area record misses fires under about 10 ha and most grass and farm fires.
Little of the land around Delta has burned: 0.5% within 5 km, 0.1% within 25 km since 1986
Fires mapped since 1986 around where Delta’s residents live, and the fuel next to their homes.
In a typical year 0.003% of the land near Delta burns; the typical Canadian town sees 0.000%, and both are low.
Within 5 km of Delta, 9.3% of the land is forest fuel; widen the ring to 25 km and it is 21%.
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 255
Oliver tops the 255 towns in British Columbia at 0.98% a year; Delta, at 0.003%, comes 191st.
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.
7.5% of Canada’s 2,610 towns burn fast enough to rank moderate or above; Delta stays low, with 92%.
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.
Delta is on the flood map inventory: 1 study, by City of Surrey
Flood studies whose area touches Delta, from NRCan’s inventory, each linked to its owner.
A 2015 study by City of Surrey covers Delta, and its map, not the inventory, shows the zones.
| Study | By | Year | Status |
|---|---|---|---|
| Serpentine & Nicomekl River Climate Change Floodplain Review Phase 2 | City of Surrey | 2015 | final |
Towns with a flood study on file
Delta 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.
Flood is shown here, never graded: a study says where a map exists, not how many of Delta’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.
High seismic risk in Delta: $0.60 per $1,000 of buildings a year
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
Roughly 19.9 times the typical $0.030: Delta’s $0.60 marks real seismic exposure.
Shaking damage a year per $1,000 of building value
At $0.60, Delta 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.
Delta is in the top tenth of Canada’s 2,611 towns for earthquake risk; 0.8% 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).
What a quake does after the shaking, fire, landslides, tsunami, falls outside NRCan’s figure for Delta.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean).
Radon runs low around Delta: 0% of tested homes over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
Delta’s survey area reads 0% over the guideline, under the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Radon runs lower around Delta than in most towns in British Columbia: 0% 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 Delta’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.
A low area share in Delta doesn’t clear a house, nor does a high one condemn it: test.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Radon tests published for the Fraser South health region, not by town
Where to get warnings in Delta
Environment and Climate Change Canada issues the weather alerts for Delta; 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 Delta come through Environment Canada and Alert Ready; the fire map is CWFIS’s.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Delta’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Delta | Low | $0.60 | 0% | Yes |
| Colebrook 3,617 · 9.0 km | Low | $0.47 | 0% | Yes |
| Strawberry Hill 37,037 · 9.0 km | Low | $0.47 | 0% | None listed |
| Tsawwassen 2,629 · 11 km | Low | $0.48 | 0% | None listed |
| Panorama Ridge 36,473 · 11 km | Low | $0.47 | 0% | Yes |
| Brownsville 23,515 · 11 km | Low | $0.47 | 0% | Yes |
| South Slope 8,989 · 11 km | Low | $0.36 | 0% | Yes |
The fire record around Tsawwassen is a touch heavier than Delta’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 Delta faces
Practical steps for Delta’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
- Earthquakes are modelled. Seismic risk is NRCan’s model of yearly building losses from shaking, averaged over many years and given for Delta’s census subdivision (a neighbourhood shows its city’s).
- 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 Delta floods.
- Wildfire counts one way. For Delta, wildfire means how much nearby land burned in the past forty years, a one-way input that can pull Risk down and nothing more.
- 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 Delta sits in.
Questions about flooding and hazards in Delta
How is Delta’s Hazard risk Grade worked out?
Hazard risk gives Delta B−, weighing earthquakes and radon and counting wildfire only against it.
How big is the earthquake risk in Delta?
About $0.60 a year per $1,000 of building value, NRCan’s long-run expectation for Delta.
Is Delta at risk of wildfire?
Some, but Delta’s low band (0.1% of nearby land burned since 1986, latest 2022) is short of the level that counts.
Is radon a problem in Delta?
The area’s survey found 0% of 70 tested homes above Health Canada’s guideline, so a three-month test is worth doing in Delta.
Does Delta flood?
Delta’s area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
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).