The investigations concluded that the fish deaths were ultimately the result of a complex interplay between short-term weather conditions and long-term influences on flows in the Darling River. The management context of large-scale water abstraction for irrigation, even under baseflows, combined with an increasing frequency of drought provided a toxic backdrop for the short-term localised conditions of extreme water temperatures, algal blooms and deteriorating water quality in the summer of 2018-19 – all things that imperil fish survival.
After the three catastrophic fish death events between December 2018 and January 2019, there were repeat events along the Darling River, at much smaller scales throughout 2019. It was not only the fish that suffered, there was also mass mortality of freshwater mussels and likely many other plants and animals relying on the river systems in this arid and remote part of the landscape. The iconic River Red Gums that line the banks of the Darling River were stressed. However, as is the nature of these ‘boom’ and ‘bust’ river systems the rains did come in early 2020, with flows providing connection throughout the river system and making their way to Menindee, offering some relief to the ecosystems and communities along the way.
The moderate flows of 2020 have been followed by larger flows in 2021 and Menindee Lakes is again nearly full – as it was in 2016 before the severe drought and the conditions that were so catastrophic for the fish.