Some impacts on water quality such as climate and catchment geology, are naturally occurring. However, human activities and their consequences have a marked influence on water quality in many parts of the State.
These impacts fall into three categories:
- Diffuse sources of pollution
Extensive land uses cause widespread disturbances of natural catchments. For example, in streams flowing through agricultural areas, water may be contaminated by soil, fertiliser and pesticide residues. In streams flowing past urban communities, runoff may bring increased turbidity and a wide range of chemical pollutants.
- Point sources of pollution
Intensive activities, such as industries and sewage treatment plants, discharge waste at a specific point.
- Reducing natural streamflows
Diverting water out of a stream for irrigation, urban and industrial uses, reduces the dilution capability of the stream, intensifying the impacts of pollutants.
Source: Water Victoria: a Resource Handbook, Dept. Water Resources, 1989 |  Dense reed growth, Crawford River,
Glenelg Basin, 1989
Photo: State of the Streams Survey, DWR, 1990 |