St Marys flood map & planning overlays
A planning-constraint profile of St Marys
(Break O'Day, TAS) - 192.01 km², mapped from live council and
state overlay data. This suburb is highly constrained.
Profile updated 12 September 2026.
Suburb-wide figures; the free map shows which overlays touch your lot.
Constraint readout
192.01 km² - this suburb is highly constrained by planning overlays.
Elevation hillshade with street names, clipped to St Marys's boundary, with the flood, bushfire and environmental overlays drawn on top.
Nearby suburbs, nearest first
Aircraft noise and flight paths over St Marys
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 to
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.
St Marys at a glance
How St Marys is zoned
Buying in St Marys? The zone and code overlays on this page are the Tasmanian Planning Scheme controls a section 337 certificate reports for a title.
Across its 192.01 km², St Marys is highly constrained by planning overlays. About 12% of the suburb sits within a mapped flood overlay, and 100% is flagged bushfire-prone. There are 13 heritage-listed sites on record, and the dominant land-use zone is Rural. The median lot measures about 5,982 m² across 838 parcels.
Who lives in St Marys
Census 2021 figures published by the ABS for the St Marys 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 848, and decile 1 within Tasmania. The national average is 1000.
Age profile
Share of St Marys's 738 residents in each ABS age band.
Population trend, 2001 to 2025
Estimated resident population of St Helens - Scamander, the wider ABS statistical area containing St Marys. There is no annual population series published at suburb level, so this describes the surrounding area rather than St Marys itself.
5,830 in 2001 to 7,219 in 2025, up 24%.
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.
St Marys 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 | the Tasmanian Planning Scheme and the LIST (Land Tasmania) |
| Bushfire-prone mapping | Mapped | the Tasmanian Planning Scheme and the LIST (Land Tasmania) |
| Zoning | Mapped | the Tasmanian Planning Scheme and the LIST (Land Tasmania) |
| Heritage and environment | Mapped where published | the Tasmanian Planning Scheme and the LIST (Land Tasmania) |
| Aircraft noise contours (ANEF) | Not held | the Tasmanian Planning Scheme and the LIST (Land Tasmania), 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 12 September 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 St Marys 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.
Published flood models are held here: a Flood Model Report is available for about 520 St Marys addresses (+$9 with the planning report).
See what's in the $9 report →St Marys planning - frequently asked
Is St Marys flood-prone?
About 12% of St Marys falls within a mapped flood overlay, against the council-wide suburb average of 13%. Modelled flood depth, velocity and flood level are held for about 520 St Marys addresses, from published flood studies; the free check on the Flood Model Report page says whether a model reaches a given address.
Is St Marys bushfire-prone?
Around 100% of St Marys is mapped as bushfire-prone, compared with a Break O'Day average of 99%.
Is St Marys under a flight path?
No aircraft were observed over St Marys in the period sampled (recent weeks to now). Sampling is intermittent, so that is a floor rather than proof that none fly over. 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 St Marys?
The dominant planning zone in St Marys is Rural, though the suburb also includes Agriculture and Environmental Management.
Does St Marys have heritage-listed places?
St Marys has 13 heritage-listed places on record.
What is the typical lot size in St Marys?
Across 838 surveyed parcels in St Marys, the median lot size is about 5,982 m².
What is the population of St Marys?
At the 2021 Census St Marys had 738 usual residents, with a median age of 56 and an average household size of 2.0 people. The wider St Helens - Scamander statistical area, which contains St Marys, went from 5,830 people in 2001 to 7,219 in 2025, up 24%.
Is St Marys an advantaged suburb?
On the ABS SEIFA 2021 index of relative socio-economic advantage and disadvantage (IRSAD), St Marys scores 848 and sits in decile 1 of 10 nationally and decile 1 within Tasmania (decile 1 is the most disadvantaged tenth, decile 10 the least).
What is the median household income in St Marys?
Median household income in St Marys was $759 a week at the 2021 Census, against $900 for the typical suburb in Break O'Day. Median rent was $205 a week and the median mortgage repayment $867 a month.
Compare nearby suburbs
| Nearby suburb | Distance | Flood mapped | Bushfire-prone |
|---|---|---|---|
| Cornwall | 4.7 km | 3% | 99% |
| Gray | 6.8 km | 6% | 100% |
| Four Mile Creek | 9.8 km | 10% | 100% |
| Falmouth | 10.5 km | 16% | 99% |
| Chain Of Lagoons | 11.1 km | 14% | 100% |
| Scamander | 15.5 km | 30% | 97% |
| Upper Scamander | 16.3 km | 9% | 100% |
| Seymour | 18.5 km | 38% | 97% |
| Fingal | 20.4 km | 13% | 100% |
| Beaumaris | 21.2 km | 10% | 99% |