Coasts, Estuaries and the Sea

Water Quality

The quality of Victoria’s marine and estuarine water varies greatly, with much of this variation attributable to natural differences between sites. At the extremes, water quality is thought to be best in the open ocean, where water is highly mixed and remote from pressures. In contrast, in partially enclosed estuaries close to intensive human uses, water quality can be extremely variable.

There are a number of important water quality parameters measured by the EPA to ensure that marine and estuarine systems continue to be able to provide for beneficial uses, such as fishing, swimming and other forms of recreation. These are: the degree of eutrophication, which is caused by the influx of nutrients and reduced dissolved oxygen; turbidity, which is the amount of suspended solids in water; the presence of toxins such as heavy metals which can be harmful to marine animals as well as humans who use the marine environment; and recreational water quality, specifically the concentration of enterococci, a group of bacteria harmful to human health.

This section uses these indicators to explore the condition of Victoria’s marine and estuarine environments. It also looks at the changing pressures on water quality, such as dredging, the intensity of adjacent land uses and the effects that climate change has on reducing stream flows into estuarine environments. Finally, it evaluates government programs designed to manage pressures on marine and estuarine water quality and uses recommendations to suggest ways that Victoria’s marine water quality may be protected and improved for present and future generations.

Part 4.4.2 - Water Quality Coasts Esturaries and Sea (PDF - 1.3 MB)