Stormwater Pollution

Stormwater is run off from rain that falls on roofs, roads, and open spaces. As urban stormwater runoff flows through street drains and pipes to creeks, rivers, estuaries and the ocean, it collects and carries many types of pollutants. Stormwater runoff from urban environments typically contains litter, bacteria, nutrients, chemicals, pesticides, metals, sediment, and vegetation. Sources include road surfaces, industrial and commercial premises, parks, gardens, degraded riparian areas, bush fires, boats, and households. Urban stormwater contaminated with sewage overflows and animal faeces is a significant source of bacterial and nutrient contamination of our local waterways after rain.

In rural and other less developed lands, pollutants and their sources are dispersed over areas which are large compared to the urban environment. Some sources are unique to rural settings, such as broadacre cropping, irrigation farming, grazing and intensive livestock industries. Land clearing (particularly historical clearing) and some agricultural techniques have increased the amount of sediment delivered to waterways.

The five main types of stormwater pollutants are:

  • Litter such as cigarette butts, cans, food wrappers, plastic bags and drink bottles
  • Chemical pollution such as car wash detergent, excess garden fertilisers, paint, oil and grease
  • 'Natural' pollution such as leaves, lawn clippings and dog poo
  • Sediment pollution such as soil erosion and runoff from building sites and cleared bushland
  • Pathogens, such as viruses and bacteria from leaking septic tanks and sewerage overflow.

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