Mount Colah flood map & planning overlays
A planning-constraint profile of Mount Colah (Hornsby, NSW) - 11.44 km², mapped from live council and state overlay data. This suburb is highly constrained.
Everything below is suburb-wide. Overlays change block to block - see which ones actually touch your lot. The map is free.
Constraint readout
11.44 km² - this suburb is highly constrained by planning overlays.
Elevation hillshade with street names, clipped to Mount Colah's boundary, with the flood, bushfire and environmental overlays drawn on top. It shows where constraints fall; the interactive map shows them on your exact address.
Mount Colah at a glance
How Mount Colah is zoned
Buying in Mount Colah? The zoning, flood and bushfire lines on the section 10.7 certificate attached to the contract are mapped controls - see our s10.7 certificate guide.
Across its 11.44 km², Mount Colah is highly constrained by planning overlays. Flood mapping covers the suburb and none of it falls within a mapped flood overlay, and 86% is flagged bushfire-prone. There are 9 heritage-listed sites on record, and the dominant land-use zone is National Parks and Nature Reserves. The median lot measures about 780 m² across 2,504 parcels. These figures are suburb-wide - the overlays that actually apply to a given lot can differ block to block, which is what a property-level check tells you.
Who lives in Mount Colah
Census 2021 figures published by the ABS for the Mount Colah suburb boundary itself, not a wider region.
Socio-economic standing
ABS SEIFA 2021 ranks every Australian suburb. Decile 1 is the most disadvantaged tenth of the country, decile 10 the least.
Score 1104, and decile 10 within New South Wales. The national average is 1000.
Age profile
Share of Mount Colah's 7,816 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of Asquith - Mount Colah, the wider ABS statistical area containing Mount Colah. There is no annual population series published at suburb level, so this describes the surrounding area rather than Mount Colah itself.
18,145 in 2001 to 23,527 in 2025, up 30%.
Source: Australian Bureau of Statistics. Census of Population and Housing 2021 (General Community Profile) and SEIFA 2021, both published at the Suburbs and Localities level; Regional Population (estimated resident population) at Statistical Area Level 2. Used under CC BY 4.0. Census counts of small populations are randomly adjusted by the ABS to protect confidentiality, so figures for small suburbs are indicative.
Mount Colah data sources and coverage
Every figure below is an aggregate for the suburb boundary. “Not mapped” means LayeredGeo does not hold a source layer covering this suburb; it is never an all-clear for a particular property.
| Dataset | Coverage | Publisher |
|---|---|---|
| Flood mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Bushfire-prone mapping | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Zoning | Mapped | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Heritage and environment | Mapped where published | NSW Government spatial services, NSW ePlanning and published council flood studies |
| Demographics | Available | Australian Bureau of Statistics (2021 Census and SEIFA) |
Profile last materially updated 5 August 2026. See the methodology and full source list. Source data changes over time and critical decisions should be checked with the responsible authority.
Check a specific Mount Colah address
See exactly which overlays touch a single property - the interactive map is free. Need it on paper? A full planning PDF is just $9.
See what's in the $9 report →Mount Colah planning - frequently asked
Where can I see a flood map of Mount Colah?
The schematic on this page is a Mount Colah flood map: the mapped flood overlays drawn over the suburb's terrain and street grid. Flood lines vary block to block, so for a specific property use the free interactive map - search any Mount Colah address and it shows the flood, zoning and bushfire mapping on the exact lot boundary.
Is Mount Colah flood-prone?
Flood mapping covers Mount Colah and none of the suburb falls within a mapped flood overlay (the council-wide suburb average is 2%). Flood overlays vary block to block, so whether a particular lot is affected needs a property-level check.
Is Mount Colah bushfire-prone?
Yes - around 86% of Mount Colah is mapped as bushfire-prone, compared with a Hornsby average of 69%. A bushfire-prone designation can trigger additional building requirements, so check the specific address.
What is the zoning in Mount Colah?
The dominant planning zone in Mount Colah is National Parks and Nature Reserves, though the suburb also includes Low Density Residential and Infrastructure. Zoning sets what you can build and do on a site, and can differ lot by lot.
Does Mount Colah have heritage-listed places?
Mount Colah has 9 heritage-listed places on record. Heritage listing affects what you can alter or demolish, so confirm whether a specific property is listed or near a heritage place.
What is the typical lot size in Mount Colah?
Across 2,504 surveyed parcels in Mount Colah, the median lot size is about 780 m². There are also 49 registered easements mapped in the suburb - an easement can restrict where you can build, so always check the title and overlays for the specific lot.
Does Mount Colah have a train station?
Yes - Mount Colah has 1 train station: Mount Colah Station. It is also served by 157 bus stops.
What is the population of Mount Colah?
At the 2021 Census Mount Colah had 7,816 usual residents, with a median age of 40 and an average household size of 2.9 people. The wider Asquith - Mount Colah statistical area, which contains Mount Colah, went from 18,145 people in 2001 to 23,527 in 2025, up 30%. ABS publishes no annual population series for individual suburbs, so that trend describes the surrounding area rather than Mount Colah alone.
Is Mount Colah an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Mount Colah scores 1104 and sits in decile 10 of 10 nationally and decile 10 within New South Wales - decile 1 being the most disadvantaged tenth of Australian suburbs and decile 10 the least. The national average score is 1000. SEIFA summarises income, education, occupation and housing across the whole suburb, so it describes the area, not any particular household in it.
What is the median household income in Mount Colah?
Median household income in Mount Colah was $2,505 a week at the 2021 Census, against $2,468 for the typical suburb in Hornsby. Median rent was $525 a week and the median mortgage repayment $2,544 a month. These are 2021 Census figures and have not been indexed to today.
Do I need a planning report for a Mount Colah property?
A Mount Colah planning report pulls every overlay - zoning, flood, bushfire, heritage and environmental - that touches a single lot, on live council and state data. The interactive map preview is free; a full PDF report is $9.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Hornsby Heights | 1.9 km | 0% | 94% |
| Asquith | 2.6 km | 0% | 52% |
| Mount Kuring-Gai | 2.8 km | 0% | 96% |
| North Wahroonga Ku-Ring-Gai |
3.8 km | 0% | 87% |
| Hornsby | 4.1 km | 0% | 50% |
| North Turramurra Ku-Ring-Gai |
4.4 km | 0% | 86% |
| Waitara | 5.0 km | 0% | 0% |
| Galston | 5.2 km | 0% | 81% |
| Berowra | 5.3 km | 0% | 87% |
| St Ives Chase Ku-Ring-Gai |
6.2 km | Not mapped | 75% |