Stormwater management

Stormwater is rainwater in urban environments that runs off hard surfaces like roads, footpaths, driveways and roofs. It often flows from property drains to street gutters operated by local councils. Gutters may connect to large channels, pipes and creeks, which form our stormwater drainage systems.

We manage parts of the stormwater network and work with councils and other agencies to keep it operating well. The network moves water through open channels and underground pipes.

Keeping pollutants out of major waterways

We install stormwater quality improvement devices (SQIDs) to help clean stormwater before it reaches major waterways. SQIDs include trash racks, gross pollutant traps and floating litter traps, also known as litter booms.

We've done some work integrating water sensitive urban design (WSUD) into parks and other areas around Sydney. WSUD includes natural, planted vegetation areas that filter stormwater through physical and biological processes.

Healthier waterways create new habitats for wildlife and revitalised spaces for the community to enjoy.

We have worked with local councils and State government agencies to manage the stormwater system and improve our large stormwater channels and drains. We have naturalised channels that needed to be replaced or rehabilitated by replacing steep concrete channel walls with gentle slopes stabilised by rock and native plants. Naturalisation boosts habitat for native animals, urban greening and cooling, public spaces, and longevity for channels.

Caddies Creek catchment is flood-affected trunk drainage land that we own around Caddies Creek and Second Ponds Creek (the Rouse Hill Development Area). Trunk drainage land typically includes creeks, bushland, or parks and reserves with stormwater pits or small concrete channels in the middle.

The land isn't developed for housing. It's reserved to help manage stormwater from large storms and help prevent flooding. It also creates habitat for native plants and animals. In this trunk drainage land, we:

• plant local native species
• remove weeds and invasive species
• remove rubbish and sediment.

Restoring local creeks and waterways improves the quality of water going into the Hawkesbury-Nepean River.

We own the Botany Wetlands, the largest coastal freshwater wetlands in Sydney. They cover a 4.5-kilometre corridor in Sydney's east, and we lease most of the surrounding area to golf clubs. The wetlands have significant ecological and heritage value. They also provide important recreational, educational and scientific value to the community.

Stormwater in channels, creeks, and coastal rivers can rise quickly during heavy or prolonged rain. How quickly floods happen and how long they last depend on soil type, storm length and intensity, topography (landscape), land use and development. Hard surfaces in urban areas make rainwater run off faster.

Local councils have primary responsibility for flood planning in their areas. They follow the process in the NSW Government's flood risk management manual.

We help reduce flooding by:

• maintaining our stormwater assets so they work as intended
• assessing developments near our stormwater assets to manage flood risks
• working with councils to identify flood risks and improve stormwater systems.

Stormwater harvesting involves collecting, storing and treating stormwater to be recycled for things like irrigating parks and toilet-flushing.

The integrated water cycle management system in the new Aerotropolis Precinct will be the largest stormwater harvesting scheme in Australia. Find out about our Western Sydney Aerotropolis Stormwater project or visit the Aerotropolis Integrated Stormwater Scheme.

Our stormwater systems include open channels, drains, tunnels and maintenance holes. They can be dangerous. Only authorised maintenance crews can enter them safely.

• Water can rise fast and unexpectedly, even if it's not raining.
• Shallow flowing water can be powerful enough to knock you over.
• Stormwater may contain dangerous chemicals, disease-causing bacteria and other pollutants.