Environmental issues

Water quality

Diffuse source water pollution

Diffuse source water pollution is less commonly recognised than point source water pollution because it arises in a catchment from many different sources that do not have an obvious discharge point. Diffuse source water pollution is caused when pollutants from a range of dispersed urban and rural land use activities contaminate our waterways.

An important characteristic of diffuse source water pollution is that it mainly results from rainfall runoff, particularly during storms. As water flows over land it picks up pollutants and moves them into rivers, lakes, estuaries, beaches and groundwater. Common sources of pollution include runoff from road surfaces, urban developments, construction sites, parks and gardens, and farms.

Diffuse source water pollution is one of the key impacts on water quality in our waterways. In some waterways it is the largest source of pollutants.

Pollutants in runoff commonly include:

  • nutrients, e.g. from overuse of fertilisers
  • sediments, e.g. from soil erosion
  • pathogens, e.g. bacteria from leaking septic tanks
  • toxicants, e.g. pesticides
  • salts, e.g. from dryland salinity
  • acids, e.g. from acid sulfate soils in drained wetlands
  • gross pollutants, e.g. litter.

Diffuse source water pollution by its nature is complex to manage however, as it is closely linked to land use. Government, councils, industry, landholders and individuals can all play a part in its reduction.

To assist in better management of diffuse water pollution the State's natural resource managers have developed the NSW Diffuse Source Water Pollution Strategy. These webpages aim to bring together useful information to help with the management of diffuse source water pollution, including:

  • information to assist land managers to identify and address diffuse source water pollution hotspots
  • information about potential funding sources for activities and projects aimed at addressing diffuse source water pollution issues.

Examples of good and poor diffuse source water pollution management are shown in the following diagram.

Diffuse source water pollution management examples



Page last updated: 10 August 2011