In March of 2021 researchers from the University of Sydney labelled the Murray Darling river system to be one of the top 5 regions of “high-concern” as part of a global analysis for risk of pesticide pollution.
The team, led by the University of Sydney’s Fiona Tang, found that nearly two-thirds of agricultural land across the globe was ‘at risk’ of pollution from pesticides, with roughly a third being identified as ‘High Risk’.
The research team defined regions ‘at risk’ to be those where pesticide residues in the environment were recorded at levels above what is deemed to have no effect. ‘High Risk’ referred to environments where pesticide residues were 1000 times higher than the safe level.
Co-author of the study, Federico Maggi from the Institute of Agriculture, noted that the Murray Darling basin was at particular risk and was categorised alongside 4 other regions across the world as of ‘High Concern’ due to the combination of both a high biodiversity and the area suffering from water scarcity issues.
This risk of pesticide pollution has been highlighted as a result of the 2023 Menindee Fish Kills. Despite the NSW EPA stating, after investigating the event, that “a pesticide pollution event was ruled out with results coming back negative for more than 600 pesticides,” a separate investigation conducted by Charles Sturt University found that:
“...several herbicides including metolachlor, atrazine, simazine, terbuthylazine, tebuthiuron, clopyralid, fluroxpyr were detected from the laboratory-analysed water samples, and, where ANZECC guideline values were available, generally exceeded acceptable concentrations."
Sources & Further Reading
https://cosmosmagazine.com/earth/agriculture/pesticides-put-two-thirds-of-agricultural-land-at-risk/