Almost 3.5 million people depend on the water of the Murray–Darling Basin for their everyday use. Multi-million dollar industries rely on the same water to remain productive, a diverse range of plants and animals rely on the well-being of river systems to survive, and over one-third of the nation’s food is produced in the Basin.
Basin communities, industries and the environment all rely on good quality water to flourish. To make sure the Basin’s water stays fit for purpose, the Basin Plan sets out certain water quality objectives and targets to be achieved. Each Basin state government is responsible for measuring water quality in their state, and the Murray–Darling Basin Authority assists by overseeing the River Murray water quality monitoring program on behalf of Basin state governments. The River Murray program allows uniform water quality data to be collected, measured and analysed to help us gain an understanding of the current and long-term trends of river health within the River Murray system.
To gather water quality data, water samples are collected at regular intervals from 28 sites along the River Murray and across its major tributaries such as the Goulburn, Ovens, Darling and Murrumbidgee Rivers in New South Wales, Victoria.
Samples from each of these sites are analysed through a series of tests, including:
- electrical conductivity – measures salinity levels
- pH testing – measures how acidic the water is
- temperature –influences many other water quality indicators
- turbidity – measures how clear the water is. Unclear, or turbid, water is often seen as an indicator for pollution and influences the growth rate of aquatic plants and animals and quality of habitat
- phosphorous and nitrogen levels – as in indicator for possible algal growth
At some of the monitoring locations, the program also conducts biological monitoring of aquatic macroinvertebrates, such as insects. Different water bugs have varying sensitivity to changes in water quality, so their presence or absence is used as an indicator of the health of the River Murray in response to changes in flow, water quality, river management and climate.
Analysing these water quality measurements allows waterway health to be assessed, sources of pollution to be detected and allows water managers to anticipate or respond to changes in waterway condition, such as sudden algal blooms or blackwater events (when water turns black due to the presence of large amount of organic material).
The data produced provides an extensive record of water-quality throughout the Basin, with the results being used to inform water management and ensure the water quality targets set out in the Basin Plan are met. These targets ensure the water across the Basin is of high enough quality so that it remains suitable for drinking, agricultural, recreational and environmental purposes.