Photo: Annichou · CC BY-SA 3.0Flood mapping exists for Overbrook: 1 on record, latest by Rideau Valley Conservation Authority
Since 1986 almost nothing has burned near Overbrook: 0% of the land within 25 km, or 0.000% a year. Earthquakes add more: NRCan’s model puts building losses at $0.15 a year per $1,000 of value, against $0.030 for the typical town. About as many homes carry radon around Overbrook as elsewhere, 6.2% over the guideline where the typical town has 6.6%. Overbrook grades C+ for hazard risk; wildfire is low here, so it earns no credit.
What stands out about Overbrook’s hazards
Four national sources, each read for Overbrook: earthquakes, radon, past fires and flood studies.
What Overbrook faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Overbrook grades C+ for hazard risk
Risk averages earthquakes and radon; wildfire joins only where it pulls the average down, so a town like Overbrook with little fire nearby would get no credit for it.
Its place: #703 of 866 in Ontario and #1,894 of 2,589 Canadian towns.
How sure: The seismic figure is a long-run average from NRCan’s model, not a prediction. Only 64 homes were tested in the survey area, so the radon share is rough. Small fires and grass fires are largely missing from the national burned-area record.
Few fires near Overbrook: 0% within 5 km, 0% within 25 km
Fires mapped since 1986 around where Overbrook’s residents live, and the fuel next to their homes.
Forty years of fire maps put Overbrook at 0.000% a year, low next to the typical Canadian town’s 0.000%.
The 5 km ring around Overbrook’s homes is clear of burns since 1986, the nearest 20 km out.
Homes in Overbrook sit on open or built-up ground (2.3% forest fuel within 5 km); the wider 25 km holds 8.1%.
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
Fire has taken almost none of the land around Overbrook, as for 638 of the 871 towns in Ontario; Sioux Lookout tops the list 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.
Like most of Canada’s 2,610 towns (92%), Overbrook 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.
Rideau Valley Conservation Authority has mapped flooding for Overbrook (1 study)
Flood studies whose area touches Overbrook, from NRCan’s inventory, each linked to its owner.
The flood study touching Overbrook is Rideau Valley Conservation Authority’s, dated 2016; its own map shows the zones street by street.
| Study | By | Year | Status |
|---|---|---|---|
| Rideau River, Hogs Back to Rideau Falls | Rideau Valley Conservation Authority | 2016 | final |
Towns with a flood study on file
Overbrook is one of the 69% of towns in Ontario 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.
Nothing here counts toward Risk; the studies are pointers to the maps their owners keep for Overbrook.
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.
Earthquakes cost buildings in Overbrook $0.15 per $1,000 a year
NRCan’s seismic risk model: the damage shaking is expected to do to buildings each year, on average over many years.
At $0.15 per $1,000, Overbrook carries roughly 5 times the typical Canadian town’s earthquake risk ($0.030).
Shaking damage a year per $1,000 of building value
Above the middle in Ontario: Overbrook’s $0.15 against a median of $0.043, with Alexandria highest at $0.21.
NRCan seismic risk model (2022): mean yearly building loss per $1,000 of value; medians of towns of 2,500 people or more.
15% of Canada’s 2,611 towns expect more shaking damage than Overbrook, which places it in the upper third.
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 model counts damage to Overbrook’s buildings and their occupants from shaking only: not liquefaction, landslides, tsunami or fires after a quake.
Natural Resources Canada, Canada’s Seismic Risk Model (2022), by census subdivision (2016 boundaries; a few 2021 subdivisions take their residents’ mean). · Earthquake risk: the city of Ottawa
Radon about average around Overbrook: 6.2% over the guideline
Health Canada’s survey of long-term home tests: the share above the 200 Bq/m³ guideline.
At 6.2% over the guideline, the area around Overbrook is about level with the typical Canadian town’s 6.6%.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
The median in Ontario is 4% over 200 Bq/m³; the survey area around Overbrook has 6.2%.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
Overbrook is in the 5–10% band with 37% of Canada’s 2,611 towns; 26% have more.
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.
The survey sampled homes around Overbrook; it can’t tell you your basement’s level.
Health Canada, Cross-Canada Survey of Radon Concentrations in Homes (2009–2011). · Radon tests published for the City of Ottawa Health Unit, not by town
Weather and fire alerts for Overbrook
Environment and Climate Change Canada issues the weather alerts for Overbrook; 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. |
For fires near Overbrook, the national fire information system maps danger and active fires daily; local authorities give any evacuation order.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
How Overbrook’s neighbours compare on hazards
The same four hazards for the places next door.
| Town | Wildfire | Quake $/1,000 | Radon | Flood study |
|---|---|---|---|---|
| Overbrook | Low | $0.15 | 6.2% | Yes |
| Vanier South 7,259 · 1.0 km | Low | $0.15 | 6.2% | Yes |
| Carson Grove - Carson Meadows 11,290 · 1.4 km | Low | $0.15 | 6.2% | None listed |
| Vanier North 10,498 · 1.8 km | Low | $0.15 | 6.2% | Yes |
| Manor Park 9,491 · 2.4 km | Low | $0.15 | 6.2% | Yes |
| Waterridge Village 2,737 · 2.4 km | Low | $0.15 | 6.2% | Yes |
| Riverview 14,030 · 2.5 km | Low | $0.15 | 6.2% | Yes |
Vanier North burns a little more than Overbrook, in the same low band (low here).
Radon is the survey area’s figure, so neighbours in one area share it.
Get ready for what Overbrook faces
What to do about the hazards Overbrook 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.
- 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
- 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 Overbrook floods.
- 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 Overbrook sits in.
- Earthquakes are modelled. Shaking damage is modelled from the ground, the buildings and the odds of each quake, and published for whole subdivisions such as Overbrook’s.
- Wildfire counts one way. The wildfire figure is the share of land within 25 km of Overbrook’s homes burned each year from 1986 to 2025, past fire rather than a forecast, and it can only lower Risk.
Questions about flooding and hazards in Overbrook
Is Overbrook at risk of wildfire?
Less than most of Canada: 0% of the land within 25 km of Overbrook has burned since 1986, the last in 2014, a low band that leaves Risk alone.
How is Overbrook’s Hazard risk Grade worked out?
Overbrook grades C+ for hazard risk, from earthquakes and radon, with wildfire counted only where it lowers the grade.
How big is the earthquake risk in Overbrook?
Expected earthquake damage in Overbrook comes to $0.15 a year for each $1,000 that buildings are worth.
Is radon a problem in Overbrook?
In Health Canada’s survey, 6.2% of 64 homes tested in Overbrook’s area were above 200 Bq/m³, though only a test tells you about one house.
Does Overbrook flood?
Overbrook’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).