Lower Portland flood map & planning overlays
A planning-constraint profile of Lower Portland
(The Hills Shire, NSW) - 59.67 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
59.67 km² - this suburb is highly constrained by planning overlays.
Elevation hillshade with street names, clipped to Lower Portland'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 Lower Portland
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 1 a day
Night movements: observed, lowest 6,000 ft - night is sampled as often as day, but night traffic is light, so this is a floor and no rate can be put on it.
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.
Lower Portland at a glance
How Lower Portland is zoned
Buying in Lower Portland? 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 59.67 km², Lower Portland is highly constrained by planning overlays. About 20% of the suburb sits within a mapped flood overlay, and 97% is flagged bushfire-prone. There are 24 heritage-listed sites on record, and the dominant land-use zone is Rural Landscape. The median lot measures about 52,431 m² across 419 parcels.
Who lives in Lower Portland
Census 2021 figures published by the ABS for the Lower Portland 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 1026, and decile 7 within New South Wales. The national average is 1000.
Age profile
Share of Lower Portland's 711 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 Lower Portland. There is no annual population series published at suburb level, so this describes the surrounding area rather than Lower Portland 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.
Lower Portland 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 Lower Portland 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 40% of Lower Portland. 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 Lower Portland. 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 Lower Portland lot.
See what's in the $9 report →Lower Portland planning - frequently asked
Is Lower Portland flood-prone?
About 20% of Lower Portland falls within a mapped flood overlay, against the council-wide suburb average of 9%. Published flood models are held over parts of Lower Portland; the free check on the Flood Model Report page says whether one reaches a given address.
Is Lower Portland bushfire-prone?
Around 97% of Lower Portland is mapped as bushfire-prone, compared with a The Hills Shire average of 62%.
Is Lower Portland under a flight path?
Aircraft were observed below 3,000 ft over about 40% of Lower Portland, and over about 62% 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 500 ft, with an average of 4,000 ft. At the busiest point in the suburb about 2 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 Lower Portland?
The dominant planning zone in Lower Portland is Rural Landscape, though the suburb also includes Primary Production and Environmental Living.
Does Lower Portland have heritage-listed places?
Lower Portland has 24 heritage-listed places on record.
What is the typical lot size in Lower Portland?
Across 419 surveyed parcels in Lower Portland, the median lot size is about 52,431 m². There are also 8 registered easements mapped in the suburb.
Does Lower Portland have a train station?
There is no train station inside Lower Portland itself. The suburb is served by 4 bus stops.
What is the population of Lower Portland?
At the 2021 Census Lower Portland had 711 usual residents, with a median age of 46 and an average household size of 3.0 people. The wider Bilpin - Colo - St Albans statistical area, which contains Lower Portland, went from 2,518 people in 2001 to 2,781 in 2025, up 10%.
Is Lower Portland an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), Lower Portland scores 1026 and sits in decile 8 of 10 nationally and decile 7 within New South Wales (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in Lower Portland?
Median household income in Lower Portland was $1,965 a week at the 2021 Census, against $2,650 for the typical suburb in The Hills Shire. Median rent was $400 a week and the median mortgage repayment $2,342 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Cumberland Reach Hawkesbury |
2.3 km | 55% | 91% |
| Leets Vale | 4.8 km | 28% | 96% |
| Sackville North | 5.3 km | 32% | 92% |
| Sackville Hawkesbury |
5.6 km | 55% | 93% |
| Maroota | 7.2 km | <1% | 93% |
| Ebenezer Hawkesbury |
8.4 km | 41% | 92% |
| Colo Hawkesbury |
8.6 km | 0% | 100% |
| Blaxlands Ridge Hawkesbury |
8.6 km | 5% | 100% |
| South Maroota | 9.3 km | 6% | 99% |
| Wisemans Ferry Hornsby |
10.0 km | 35% | 86% |