Waterway Health

Waterway Health

Our City is lucky to have the beautiful Nepean River and many creeks. Council and our community care about the health of these waterways.

Ways we work for healthy waterways include:

  • stormwater management
  • rehabilitation projects
  • water sensitive urban design

Stormwater is rainwater that doesn't soak into the ground but flows from roofs, driveways, gutters and roads into the stormwater system. Urban environments generate a lot of stormwater because of all the hard surfaces.

Stormwater runs into our creeks and rivers. Unlike sewage, it isn't treated before it goes into the waterways.

Any litter, garden waste, oil or other chemicals that the water collects from hard surfaces like roads and in the gutters will end up in the waterways we use for swimming, fishing and recreation.

Council is responsible for stormwater management, which involves transporting this rainwater from urbanised areas to the natural waterways. We build and maintain pathways and gutters.

We install and empty Gross Pollutant Traps (GPTs) to reduce the amount of litter that gets into the stormwater system.  

What you can do to help

Build a vegetable raingarden at home. Not only will a raingarden capture stormwater runoff from the roof, it will also provide a self-watering vegetable garden for your backyard. Download the How to Build a Vegetable Raingarden brochure for step-by-step instructions on what to do. How to Build a Vegetable Raingarden brochure (Chinese) is also available for download in Chinese.

Please help keep pollutants out of our stormwater to improve the quality of our waterways.

Council's Water Sensitive Urban Design Policy was adopted in December 2013. The policy includes controls to reduce the impact of urban development on the health of the Nepean River and local waterways. The policy also links to our City Strategy 2013, builds on previous Stormwater Management Plans and complements Council's work with our community to protect our environment now and for the future.

What is Water Sensitive Urban Design (WSUD)?

WSUD is the sustainable management of water in urban areas through intelligent and integrated design. It considers all aspects of the urban water cycle including potable (drinking quality) water, rainwater, wastewater, stormwater and groundwater.

Key principles include: 

  • minimising the impact of urbanisation on the natural water cycle
  • protecting and enhancing the natural aspect of landscapes
  • treating urban stormwater for reuse or release to receiving waters
  • reducing drinking water demand through water efficiency, stormwater harvesting and wastewater reuse, and
  • integrating vegetated stormwater treatment and harvesting systems into the landscape to provide microclimate benefits that reduce the 'urban heat island effect'.

Stormwater impacts

When rain falls on vegetated areas such as bushland it is filtered by soil and plants, and soaks back into the ground. When rain falls on hard surfaces such as rooftops and roads it cannot soak into the ground and becomes stormwater runoff. Stormwater runoff picks up pollution such as dirt, chemicals, and litter, carrying them into stormwater drains and into waterways. These pollutants contains nutrients that can cause algal growth.

What is a bioretention basin and what does it do?

Bioretention basins are designed to remove a wide range of pollutants from stormwater runoff. When stormwater is redirected into the bioretention basin it ponds temporarily before being slowly filtered by native plants. As the stormwater seeps through the layers of soils, sand and gravel, the plants absorb nutrients like nitrogen and phosphorus. Fine sediments and other pollutants are also captured. Bioretention basins also reduce the amount of stormwater that would otherwise wash pollutants into river and creeks.

Download more information here

What does the policy mean for my development? 

The policy introduces a framework for industrial, residential and commercial developments to improve stormwater quality and reduce potable water consumption to help restore the natural water cycle. It details catchment management and water quality controls which depend on a development's scale and type. Performance criteria outlined for stormwater conservation, quality and quantity would apply to developments including:

  • Residential development of 5 or more dwellings including multi dwelling housing, residential housing residential flat buildings and mixed use development.
  • All new commercial, retail, mixed use and industrial development greater than 2,500m2 total site area and alterations and additions where the increase in the roofed and impervious area is equal to or greater than 250m2.
  • Residential (5 or more lots) or commercial and industrial subdivision.
  • Any development which results in an increase of the existing impervious area by greater than 250m2. Development includes but is not limited to additional roads, driveways, vehicle parking areas, loading and storage areas.

The policy evaluates total gross pollutants, total suspended solids (TSS), Nitrogen (TN) and Phosphorus (TP) and includes a flow management target to reduce erosion within creeks. A WSUD Strategy would also be required under the policy including stormwater modelling to demonstrate how targets can be met.

See the Water Sensitive Urban Design Technical Guidelines and Addendum 1: Deemed to Comply Toolkit for Residential, Industrial & Commercial Developments which help industry comply with the Policy. They will be regularly reviewed and updated to reflect changes within the industry and best practice.

You can also read our Water Sensitive Urban Design Policy fact sheet.