Photo: P199 · Public domainHazard risk in Lanark Highlands is higher than in 90% of Canadian towns
Fire seldom reaches Lanark Highlands: since 1986, 0.1% of the land within 25 km has burned (0.002% a year). Seismic risk runs high: $0.066 of expected damage per $1,000 of buildings a year, the typical town $0.030. In Health Canada’s survey, 19% of homes tested in the area exceeded 200 Bq/m³ (6.6% typical). Hazard risk gives Lanark Highlands a grade of D, from earthquakes and radon alone.
What stands out about Lanark Highlands’s hazards
For Lanark Highlands, from NRCan’s seismic model, Health Canada’s radon survey, the national burned-area record and the flood map inventory.
What Lanark Highlands faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Wildfire
Earthquakes
Radon
Flood study
Lanark Highlands grades D for hazard risk
Seismic risk and radon set Lanark Highlands’ grade, wildfire can drag it down, and flood mapping stays out of it.
Its place: #851 of 866 in Ontario and #2,472 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.
Little of the land around Lanark Highlands has burned: 0.1% within 5 km, 0.1% within 25 km since 1986
Past fire around Lanark Highlands’ homes, from the national burned-area record, with the fuel within 5 km.
With 0.002% burned a year, Lanark Highlands is among the many low-band places (the typical Canadian town 0.000%).
About as much forest grows next to Lanark Highlands’ homes (23% within 5 km) as across 25 km (24%).
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
The land around Lanark Highlands burns at 0.002% a year, the 54th highest rate of 871 towns in Ontario; Sioux Lookout tops it 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.
Some fire is mapped around Lanark Highlands, but not enough to leave the low band, where 92% of Canada’s 2,610 towns are; 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.
Flooding around Lanark Highlands is mapped in 2 studies, the newest by Mississippi Valley Conservation Authority
What Canada’s Flood Map Inventory lists for Lanark Highlands: who studied flooding and where to see their maps.
2 studies on the inventory touch Lanark Highlands, the newest Mississippi Valley Conservation Authority’s from 2023, and their areas can be large, so they say maps exist, not that the town floods.
| Study | By | Year | Status |
|---|---|---|---|
| Lower Clyde River | Mississippi Valley Conservation Authority | 2023 | final |
| Lower Mississippi River Flood Plain Mapping Study | Mississippi Valley Conservation Authority | 2019 | final · not public |
Towns with a flood study on file
Its flood study puts Lanark Highlands with 69% of towns in Ontario; Canada’s share is 58%.
NRCan Canada Flood Map Inventory: a study footprint touching the town’s boundary; towns of 2,500 people or more.
Flood mapping around Lanark Highlands has come in steps: 2 studies from the 2010s to the 2020s.
Study dates as the NRCan inventory lists them, one count per study touching Lanark Highlands.
Listed, not scored: a flood study proves a map exists, not that Lanark Highlands floods.
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 Lanark Highlands $0.066 per $1,000 a year
Expected yearly building losses from earthquakes, from Natural Resources Canada’s model.
Lanark Highlands’ $0.066 is about 2.2 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
At $0.066, Lanark Highlands is above the typical town in Ontario ($0.043); Alexandria has the most 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.
More earthquake risk than most: only 29% of Canada’s 2,611 towns are above Lanark Highlands.
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 Lanark Highlands 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).
Radon runs high around Lanark Highlands: 19% of tested homes over the guideline
Long-term radon tests in homes across the survey area, against Health Canada’s guideline.
Lanark Highlands’ area, at 19%, is above the 6.6% of the typical Canadian town, so testing is worth more here than most places. Lanark Highlands doesn’t get its own radon tests figures; the ones here come from the Leeds, Grenville and Lanark District Health Unit.
Tested homes over 200 Bq/m³
Over 600 Bq/m³
Around Lanark Highlands, 19% of tests were over 200 Bq/m³ and 1.9% over 600, against a median of 4% in Ontario.
Health Canada radon survey (2009–2011), by 2007 health region; medians of towns of 2,500 people or more.
More high tests than most: Lanark Highlands sits in a band that only 22% of Canada’s 2,611 towns share, with 4.6% above.
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 Lanark Highlands 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 Lanark Highlands
Alerts for Lanark Highlands 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. |
Alert Ready carries evacuation orders for Lanark Highlands to phones; CWFIS shows the day’s fire danger.
Weather alerts (ECCC) · Alert Ready · Fire danger and active fires (CWFIS)
Get ready for what Lanark Highlands faces
Practical steps for Lanark Highlands’ 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
- Earthquakes are modelled. The earthquake figure is an expected loss, not a forecast, worked out by NRCan for each census subdivision, Lanark Highlands’ included.
- 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 Lanark Highlands 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 Lanark Highlands sits in.
- 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 Lanark Highlands.
Questions about flooding and hazards in Lanark Highlands
Is Lanark Highlands at risk of wildfire?
Not much by Canadian standards: Lanark Highlands’ band is low, with 0.1% of the land within 25 km burned since 1986 (last in 2025), so wildfire doesn’t change its grade.
Does Lanark Highlands flood?
Lanark Highlands’ area has been studied for flooding, and the owner’s map shows which streets lie in a zone; the grade leaves flood out.
How big is the earthquake risk in Lanark Highlands?
In NRCan’s seismic model, Lanark Highlands’ buildings lose $0.066 per $1,000 of value in an average year.
How is Lanark Highlands’s Hazard risk Grade worked out?
Lanark Highlands’ Hazard risk grade is D, built on earthquakes and radon with a one-sided wildfire input.
Is radon a problem in Lanark Highlands?
19% of the 108 homes Health Canada tested around Lanark Highlands topped the guideline; your own house needs its own test.
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).