Monitoring the water environment
It is important to monitor the health of our aquatic environments. This includes monitoring the health of the fish and other animals that live in aquatic environments, as well as monitoring for any possible pollutants. Checking the quality of water and the environmental health of aquatic environments involves measuring physical, chemical and biological parameters.
| Types of water quality test | Examples of what can be monitored |
|---|---|
| Biological | Bacteria, algae |
| Physical | Temperature, turbidity and clarity/light availability, colour, salinity, suspended solids, dissolved solids |
| Chemical | Nutrients, pH, dissolved oxygen, toxicants |
| Aesthetic | Odours, taints, colours, floating matter |
| Radioactive | Alpha, beta and gamma radiation emitters |
One location where EPA conducts monitoring is at Western Port. This region is approximately 70 kilometres south-east of the centre of Melbourne.
Some of the water quality tests at Western Port include chemical and physical measurements of:
pH
This test indicates whether the water is neutral, acidic or basic. A pH of 7 indicates that the water is neutral, below 7 is acidic and above 7 is basic.
Salinity
Salinity is a measure of the amount of salt in the water.
Light availability – suspended solids and secchi disk depth
Suspended solids is a measure of the level of sediment and organic matter such as algae suspended in the water column, and secchi disk depth is a visual measure of water clarity.
Nutrient levels
Nutrients exist in dissolved and particulate form (attached to matter). On entering marine waters, nutrients that are attached to sediment are often de-adsorbed from the sediment particle. Dissolved nutrients are more readily available to be taken up by plants and animals. Nutrients measured in marine waters include phosphorous and nitrogen. In marine waters, nitrogen is more readily recycled than phosphorus, and is therefore more readily available.
Toxicants
Toxicants include heavy metals such as cadmium, chromium, copper, iron, lead, mercury, nickel and zinc. They also include organic chemicals such as hydrocarbons in petroleum and pesticides and herbicides. Toxicants, even in small concentrations, can be poisonous to many living things.
Dissolved oxygen
Dissolved oxygen is an indicator of the amount of oxygen dissolved into the water column available to support aquatic life.
Biological tests
Involve sampling aquatic animals and this can give an indication of the health of the river environment as the animals live at the site for some time. They can reflect the build-up of impacts of environmental changes on the "ecosystem".
Useful animals to use for biological testing are aquatic macroinvertebrates such as insects, snails and worms as they are visible to the naked eye and are commonly found in rivers and streams.
The presence or absence of specific species provides information about environmental health. All living things in a waterway must breathe. Just as we take oxygen from the air into our lungs, water animals take oxygen from the water into their gills.
Water plants release oxygen into the water and oxygen also dissolves into the water from the air. Oxygen is needed in the waterway to clean or purify the water by breaking down the wastes in the water. When pollutants get into the water, they cut down on the amount of oxygen in the water and the waterway becomes polluted. Other pollutants can be toxic – poisonous or harmful – to aquatic species when there are enough present in the environment. Toxic pollutants include heavy metals and pesticides.
EPA has measured the biological health of aquatic environments at sites across Victoria. Each year, around 300 sites likely to be impacted by activities carried out in our catchments are chosen.