Water levels at the Menindee Lakes in western New South Wales have declined to their lowest point in five years, prompting the state government to introduce temporary upstream water restrictions amid warnings of potential mass fish deaths over the coming summer months.

Earlier this month, the combined volume of the Menindee Lakes dropped below 480 gigalitres, a level not seen since 2021. In particular, water in the upper Menindee Lakes fell under 250 gigalitres, a threshold that activates state water restrictions across parts of the northern Murray-Darling basin. These measures limit access for some irrigators with the aim of preserving water for essential human consumption and environmental needs.

The decline in water levels follows a prolonged period of below-average rainfall across the catchment in the past year. Experts caution that unless inflows to the Menindee Lakes via the Darling-Baaka River increase, there is a significant risk of large-scale fish kills during the summer. The Menindee Lakes have experienced severe fish mortality events in 2018, 2019, and most recently in 2023, when millions of dead fish were found along the Darling-Baaka’s course.

Professor Jamie Pittock of the Australian National University and the Wentworth Group of Concerned Scientists said officials are warning with considerable certainty that fish kills are likely unless greater water flows arrive in the Darling-Baaka River. “We need a major rainfall event and state governments to act by restricting irrigation to protect the system,” he noted.

Local resident Graeme McCrabb, who has been vocal since the 2018 and 2019 fish kill events, described current volumes as “drought reserve,” meaning water conservation must be a priority. While recent rainfall in Queensland has provided modest inflows across the state border, McCrabb emphasized the need for further rain to offset summer risks. He also stated that a milder summer might reduce the likelihood of fish deaths but remains concerned about the potential impact, especially if water quality deteriorates with algal growth.

In response to the situation, NSW Water Minister Rose Jackson acknowledged the severity of the challenge and said the government is focusing on protecting water quality and native fish populations. "Significant inflows would improve conditions but we aren’t sitting back and waiting for rain," Jackson said. Besides imposing water use restrictions, the government has implemented a temporary fish passage to facilitate native fish movement and established a water quality working group to monitor conditions.

Following the 2023 state election, Premier Chris Minns and senior ministers visited Menindee and pledged to investigate the recurring fish kills. An expert panel under the northern basin connectivity program previously recommended limiting upstream water extraction during dry spells to maintain flows into the Darling-Baaka River, aiming to reduce the risk of environmental disasters like fish kills and widespread drying. The panel’s final report was issued two years ago, but those recommendations have yet to be put into effect by the state government.

McCrabb expressed disappointment that no new policies have been introduced since the past fish kill events. “Government agencies have made no policy changes to improve water quality outcomes,” he said, stressing the ongoing vulnerability of the Menindee Lakes system as water levels remain critically low.