MORE than three tonnes of dead fish have been scooped out of the Darling River in NSW's far west with officials warning further hot and dry conditions will pose ongoing threats to native fish.
The NSW Department of Primary Industries estimates close to one million fish died over the weekend at Menindee - the latest in a series of mass fish deaths in the area this summer.
Officials are also investigating the death of thousands of fish on the Murrumbidgee River in Redbank Weir about 100km west of Hay.
The same weather conditions which contributed to the Menindee deaths - a period of hot weather followed by a drop in temperatures - are likely to be the cause of the Murrumbidgee event, the DPI said.
The DPI warned hot and dry conditions pose ongoing threats to native fish over the remainder of summer.
The mercury is set to remain in the mid to high 30s until Friday in Menindee before reaching 42C on the weekend.
Locals, irrigators and politicians have been arguing over who's to blame for the catastrophe with residents pointing the finger at water mismanagement.
Freshwater ecologist and Murray-Darling basin expert Angus Webb says the "world-leading" Murray-Darling Basin plan was working as intended, but it had no manual and required constant monitoring, research and adaptation.
NSW Regional Water Minister Niall Blair, who visited Menindee on Tuesday, rejected suggestions the state could have stopped water being released from the Menindee Lakes and backed the basin plan.
Australian Associated Press