Grim images continue to emerge from the Darling River in regional NSW as low oxygen levels saw millions of fish in the waterway die.
The worst mass kill to ever hit Menindee in the state’s far west has led to the activation of an emergency response centre.
Millions of decomposing fish are currently floating down the Darling River, and the situation could cause an ecological disaster that would take years for the river to recover from.
Footage tweeted by ABC reporter Bill Ormonde also showed potentially tens of thousands of yabbies appearing to clamber to the surface for air.
“Hundreds of yabbies (if not thousands or tens of thousands) climbing out of the water looking for air downriver from Menindee. Just heartbreaking,” he wrote.
The Menindee-based Emergency Operations Centre (EOC) has been set up to co-ordinate the clean-up.
It will be managed by the NSW Police, working with other agencies to remove and dispose of the fish while maintaining clean water flows to the town and surrounding areas.
According to Deputy Commissioner Emergency Management Peter Thurtell, who is also the State Emergency Operations Controller, there is no need for concern as multiple viable solutions have been identified to maintain the water supply to Menindee township and surrounding areas.
The water quality will be continually tested, and swift action will be taken if a supply switch is required.
Several agencies, including the NSW Department of Planning and Environment, Central Darling Shire Council, and WaterNSW, are involved in the response.
Landowners by the waterway, who use it as a source for irrigation, are reportedly worried about the impact it could have on their land.
On Friday, a NSW Department of Primary Industries (DPI) spokesman told news.com.au that an estimated “one million fish, predominantly bony herring (bony bream) have been affected, as well as smaller numbers of other large-bodied species such as Murray cod, golden perch, silver perch and carp”.
“This event is ongoing as a heatwave across western NSW continues to put further stress on a system that has experienced extreme conditions from wide-scale flooding,” the spokesman said.
According to the DPI, the bony herring species typically booms and busts over time.
It “booms” in population numbers during flood times and can experience significant mortalities or “busts” when flows return to normal levels.
They can also be more susceptible to environmental stresses like low oxygen levels, especially during extreme conditions such as increased temperatures currently being experienced in the area.
“These fish deaths are related to low oxygen levels in the water (hypoxia) as floodwaters recede,” the DPI spokesman said.
“Significant volumes of fish, including carp and bony herring, nutrients and organic matter from the flood plain are being concentrated back into the river channel.
“The current hot weather in the region is also exacerbating hypoxia, as warmer water holds less oxygen than cold water, and fish have higher oxygen needs at warmer temperatures.”