Protecting Homes, Waterways and Bays
Jacana retarding basin
We manage 214 retarding basins across Melbourne to help protect people and property from flooding.
Some retarding basins include wetlands that help to clean stormwater before it flows into rivers, creeks and bays.
- What are retarding basins?
- How they work
- Why we need them
- Protecting the environment
- Retarding basins as public open space
- Maintenance
- Where’s my nearest retarding basin?
What are retarding basins?
Retarding basins are built to absorb and hold stormwater, helping reduce the impact of floods on the stormwater drainage system.
The retarding basins are of varying size, and their capacity depends on the size of the catchment.
We have changed the way we design and build retarding basins, and, where possible, any new retarding basins will include stormwater treatment such as wetlands and rain gardens to help improve the health of rivers and creeks.
How they work
They are designed to catch rushing water and slow it down, taking energy out of floodwaters. They release water gradually, like a bathtub with the plug out.
If a retarding basin reaches capacity, the overflow travels down a spillway to release the flows in a controlled and safe way.
How retarding basins slow down and trap stormwater.
Why we need them
Retarding basins are critical in built-up areas. Pavements, roads and other hard surfaces create up to 35 times more run-off than rural areas, because the water can’t soak into the ground.
Retarding basins:
- reduce the impact of floods on downstream waterways
- in some cases have sediment traps and wetlands to improve water quality downstream, and function as litter traps
- in some cases support areas of significant vegetation and wildlife
- provide councils and communities with the opportunity to use extra open space.
Protecting the environment
Many retarding basins are part of the Sites of Biodiversity Significance program aimed at protecting the environmental values of places that have plants and animals of state significance.
Police Road retarding basin
Retarding basins as public open space
Although retarding basins are built primarily to protect people and property from flooding, we recognise that the community value many of these sites across Melbourne for their open space and wildlife values.
Together we can look after these sites by:
- Observing warning signs
- Keep dogs under control
- Pick up after dogs
- Take any rubbish as you leave.
Retarding basins are designed to trap stormwater run-off and can be subject to flooding during and after heavy rain.
Like drains, they receive run-off from rain anywhere in the catchment – not just the local area - so please take note of weather conditions in the area before visiting.
Maintenance
We cut grass, remove weeds and remove litter on a regular basis.
One of the main priorities of our maintenance schedule is to ensure vegetation is not blocking drainage structures.
Some vegetation is left uncut because it plays a vital role in filtering pollutants from stormwater.
At some highly urbanised sites, people may notice a temporary build-up of rubbish. This is typically litter washed by heavy rain from local roads and footpaths.
Litter is cleared on a regular basis, and we will also respond as soon as possible to reports of excess litter.
Troupes Creek West retarding basin, Narre Warren North
While retarding basins that help clean stormwater can prevent rubbish from entering rivers and creeks, this is not their primary purpose. Everyone can help keep waterways clean by binning their rubbish.
Where’s my nearest retarding basin?
There are 214 across Melbourne and beyond, from Werribee in the west, north to Macedon Ranges and east to Bass Coast. Not all retarding basins are open to the public to manage public safety risks.
Find your nearest retarding basin:
Downloads
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