Another mass fish kill event has been spotted in far western NSW, nine months after millions of fish were found dead on the nearby banks of the Darling River.

Key points: There have been over 600 fish kill events in NSW over the past 30 years

There have been over 600 fish kill events in NSW over the past 30 years The state government says to expect more this summer as drought intensifies

The state government says to expect more this summer as drought intensifies The federal government pledged $300,000 to help states manage mass fish deaths

New aerial footage appeared to show thousands of dead fish at Lake Pamamaroo in the Menindee Lakes System, near Broken Hill.

The NSW Department of Primary Industries (DPI) is yet to confirm the new kill and said in a statement it would be investigating, but the remote location would make verifying the mass kill extremely difficult.

The department said mass kills were more likely to happen throughout the summer as the ongoing drought placed increased stress on aquatic populations.

The sight of millions of dead fish floating belly-up and rotting in the sun, prompted desperate pleas by fishers and farmers and shocked Australians last summer.

But Professor Richard Kingsford, director of the Centre for Ecosystem Science at the University of NSW, flew over the area on Monday and said he doubted the footage showed the current state of the lake.

"We flew across Lake Pamamaroo and we didn't see any water along the lake," he said.

"We didn't fly across all of it, but it looked like it had been dry for quite a while."

Professor Kingsford said he did not see dead fish in the area.

Darry Clifton from the Darling River Action Group said he was not surprised by another apparent fish kill.

"There's thousands upon thousands from what I can see around the edge of that water area," he told the ABC.

"The fish are trapped, they've got nowhere to go, there's nowhere for the fish to follow the old creeks back to the actual outlet for the river."

The images of the million dead fish shocked Australians last summer. ( Supplied: Graeme McCrabb )

Mr Clifton believed the dead fish would include both native fish as well as European carp and said the local community was devastated by the thought of another mass death this year.

"To see this pristine area go down the tubes, it's just beyond belief. It's a crying shame," he said.

The federal water minister David Littleproud told RN Breakfast he was concerned by the new footage and what it meant for the summer ahead.

"This isn't the first of these fish death events, in fact there's been over 600 in NSW alone in the last 30 years," he said.

The minister on Monday released details of the federal government's Native Fish Emergency Response Plan to protect fish in the Murray Darling river system.

The plan includes up to $300,000 to help states manage extreme fish death events, maintaining a database to register fish kills and providing water to mitigate the emergency.

But Mr Littleproud admitted there was little he could do to prevent mass kills this summer when weather predictions did not include significant rainfall.

"Again [this] means there will be very minimal flows," he said.

"We're doing all we possibly can until it rains, and I just simply can't make it rain unfortunately."

John Williams is an expert in water and river management said too much water had been diverted from the river system.

Mr Williams, who is also an honorary professor at the Crawford School of Public Policy at the Australian National University, described the federal government's response as inadequate.

"We're in a desperate situation…the best we can do is a Band-Aid at the moment," he told the ABC.