Mountain Lagoon flood map & planning overlays
A planning-constraint profile of Mountain Lagoon
(Hawkesbury, NSW) - 54.66 km², mapped from live council and
state overlay data. This suburb is highly constrained.
Profile updated 3 October 2026.
Suburb-wide figures; the free map shows which overlays touch your lot.
Constraint readout
54.66 km² - this suburb is highly constrained by planning overlays.
Elevation hillshade with street names, clipped to Mountain Lagoon's boundary, with the flood, bushfire and environmental overlays drawn on top. Magenta is where aircraft were observed in the sampled period, brightest below 3,000 ft.
Nearby suburbs, nearest first
Aircraft noise and flight paths over Mountain Lagoon
Two different things, kept apart on purpose. The ANEF contour is the planning instrument - a forecast published per airport that planning schemes use to control noise-sensitive development. Observed overflight is what a sampled aircraft-tracking feed actually recorded over the suburb - where aircraft flew, how low and how often.
Observed overflight - sampled 4 Sep to 2 Oct 2026
typical observed square 0 a day
Night movements: not established - night is sampled as often as day, but too few night flights have been seen here to conclude either way.
Traffic is sampled rather than watched continuously, so every figure is a floor: aircraft not captured between samples are not represented. Rates are per 500 m square - the busiest square in the suburb, not a count of flights over the suburb - and a square is only rated where enough traffic was seen to measure it. Altitudes are above mean sea level. Flight paths change with runway use, weather, season and airspace design. This is a record of observed traffic; it is not a noise contour and not a planning control.
Mountain Lagoon at a glance
How Mountain Lagoon is zoned
Buying in Mountain Lagoon? 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 54.66 km², Mountain Lagoon is highly constrained by planning overlays. Flood mapping covers the suburb and none of it falls within a mapped flood overlay, and 100% is flagged bushfire-prone. The dominant land-use zone is National Parks and Nature Reserves. The median lot measures about 76,538 m² across 60 parcels.
Who lives in Mountain Lagoon
Census 2021 figures published by the ABS for the Mountain Lagoon 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 1044, and decile 8 within New South Wales. The national average is 1000.
Age profile
Share of Mountain Lagoon's 78 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of Bilpin - Colo - St Albans, the wider ABS statistical area containing Mountain Lagoon. There is no annual population series published at suburb level, so this describes the surrounding area rather than Mountain Lagoon itself.
2,518 in 2001 to 2,781 in 2025, up 10%.
Source: ABS Census 2021 and SEIFA 2021 (Suburbs and Localities), Regional Population (SA2), CC BY 4.0. Small counts are randomly adjusted by the ABS.
Mountain Lagoon data sources and coverage
“Not mapped” means we hold no source layer for this suburb - never an all-clear.
| 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 |
| Aircraft noise contours (ANEF) | Not held | NSW Government spatial services, NSW ePlanning and published council flood studies, Defence |
| Observed flight paths | Observed | adsb.lol, under the Open Database License |
| Demographics | Available | Australian Bureau of Statistics (2021 Census and SEIFA) |
Profile last materially updated 3 October 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 Mountain Lagoon 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.
Aircraft have been seen below 3,000 ft over about 5% of Mountain Lagoon. The report's Aircraft Overflight page narrows that to the address itself: how many aircraft a day, how low, and at what heights.
Published flood models are held over parts of Mountain Lagoon. The free check tells you whether one reaches an address; where it does, a Flood Model Report is +$9 with the planning report.
Building or pricing a slab? The $119 geotechnical desktop report covers geology, soils, bores and an indicative AS 2870 site class for a Mountain Lagoon lot.
See what's in the $9 report →Mountain Lagoon planning - frequently asked
Is Mountain Lagoon flood-prone?
Flood mapping covers Mountain Lagoon and none of the suburb falls within a mapped flood overlay (the council-wide suburb average is 24%). Published flood models are held over parts of Mountain Lagoon; the free check on the Flood Model Report page says whether one reaches a given address.
Is Mountain Lagoon bushfire-prone?
Around 100% of Mountain Lagoon is mapped as bushfire-prone, compared with a Hawkesbury average of 84%.
Is Mountain Lagoon under a flight path?
Aircraft were observed below 3,000 ft over about 5% of Mountain Lagoon, and over about 28% at any altitude up to 10,000 ft, in the period sampled (4 Sep 2026 to 2 Oct 2026). The lowest measured aircraft was at 1,000 ft, with an average of 6,000 ft. At the busiest point in the suburb about 0 aircraft a day were recorded passing over one 500 m square. Traffic is sampled rather than watched continuously and flight paths change with runway use, weather and season; the ANEF contour is the planning instrument.
What is the zoning in Mountain Lagoon?
The dominant planning zone in Mountain Lagoon is National Parks and Nature Reserves, though the suburb also includes Environmental Living and Environmental Conservation.
Does Mountain Lagoon have heritage-listed places?
No heritage-listed places are on record within Mountain Lagoon.
What is the typical lot size in Mountain Lagoon?
Across 60 surveyed parcels in Mountain Lagoon, the median lot size is about 76,538 m².
What is the population of Mountain Lagoon?
At the 2021 Census Mountain Lagoon had 78 usual residents, with a median age of 55 and an average household size of 2.3 people. The wider Bilpin - Colo - St Albans statistical area, which contains Mountain Lagoon, went from 2,518 people in 2001 to 2,781 in 2025, up 10%.
Is Mountain Lagoon an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Mountain Lagoon scores 1044 and sits in decile 9 of 10 nationally and decile 8 within New South Wales (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in Mountain Lagoon?
Median household income in Mountain Lagoon was $1,625 a week at the 2021 Census, against $2,160 for the typical suburb in Hawkesbury. Median rent was $360 a week and the median mortgage repayment $2,167 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Wheeny Creek | 6.0 km | 0% | 100% |
| Bilpin | 8.4 km | 0% | 100% |
| Upper Colo | 8.4 km | 0% | 100% |
| Kurrajong Heights | 9.3 km | 0% | 98% |
| Kurrajong | 10.6 km | 0% | 98% |
| Kurrajong Hills | 10.7 km | 0% | 100% |
| Tesselate Hill Blue Mountains |
11.8 km | 0% | 100% |
| The Slopes | 13.2 km | 0% | 100% |
| Central Colo | 13.8 km | 0% | 100% |
| Kurmond | 14.7 km | 0% | 91% |