Pollutants reach rivers from many sources. They come from run-off from agricultural land, drainage from irrigations schemes, contamination from industries, sewage overflows, urban stormwater systems and other sources across the catchment.
Polluted water can affect the health of humans and of crops, farm livestock, river plants and animals. For example:
§ salt can damage crops, soils, water supply systems and makes water unsuitable to drink
§ muddy water can suffocate life in a river, block irrigation sprays and pipes, and also leave water unsuitable to drink
§ nutrients, such as phosphorus and nitrogen from agricultural fertilisers, can encourage the growth of blue-green algae, which may cause serious health problems to humans and animals.
There are many other pollutants that affect water quality, including acidic substances, metals, pesticides and other chemical residues.
This audit follows up our 2003 performance audit ‘Protecting our rivers’ which examined whether the water quality of NSW rivers was being efficiently and effectively protected from unacceptable levels of pollution.
I believe this report will help to inform the public of the complexity and challenges that lie ahead and highlight the importance of systematically monitoring the river health and water quality of New South Wales rivers.
Peter Achterstraat
Auditor-General
May 2008