Polluted runoff is still smothering the Great Barrier Reef, our first national assessment of water quality trends in Australian rivers has revealed. The problem on the reef is getting worse, not better, despite efforts to improve farming practices and billions of dollars committed by governments to water-quality improvements. But in good news, there are signs of improvement in the Murray-Darling Basin, where less salt, sediment and phosphorous were detected in the water.
Our latest research quantifies, for the first time, how water quality in Australian rivers has changed over the past two decades. Around half our monitoring sites experienced significant changes in water quality between and on every measure we analysed. But the results for the reef and the basin stood out. In particular, freshwater flows into the Great Barrier Reef lagoon contained increasing levels of sediment and phosphorous.
If the trend continues, we have serious concerns for the health of the Great Barrier Reef and the tourist industry it supports. We studied water quality monitoring data from river sites across Australia. The relevant agency in each state and territory collects this information and makes it available online. The data covers the following:.
We focused on sites with records of all five water quality indicators from to River flows can vary enormously from year to year and this affects water quality. So we used statistics to account for this and identify underlying long-term trends. In the catchments that exhibited significant changes between and , about half showed improvements in dissolved oxygen, salinity and phosphorus, while the other half deteriorated.
Two regions experienced the greatest large-scale changes in water quality over that time: the North East Coast basin and the Murray-Darling Basin. The research analysed two decades of water quality monitoring data from sites dotted across Australia.
