The NSW government has blamed the weather for an “unprecedented” fish kill at Menindee but the regional water minister has admitted if he could go back in time he would turn off valves to prevent the system drying out.

The government, in an interim report released on Thursday, said the “ecological disaster” was caused by low rainfall and large temperature variants in the weeks before the kill leading to an algal bloom that sucked oxygen from the water.

Regional Water Minister Niall Blair also blamed Canberra and the Murray-Darling Basin Authority for authorising water releases from the Menindee basin when water levels were higher.

He said the NSW government raised concerns about water being drained out of the lakes when the authority was in charge which did result in the rate being slowed in 2016 due to “community concerns”.

But having witnessed the fish deaths and visited drought-ravaged towns, Mr Blair now wishes he could travel back in time.

“If I could go back and shut the valves off and keep all the water and have prevented that fish kill – yeah I’d take that any day of the week,” Mr Blair told reporters in Sydney on Thursday.

But, the minister added, he would have been challenged in courts across the country and faced strong opposition from environmental groups downstream in South Australia.

Labor water spokesman Chris Minns says Mr Blair couldn’t pass the buck because NSW was in charge of the last 480 gigalitres in the lakes from late 2017.

“That’s 480 gigalitres of water that Niall Blair is responsible for,” Mr Minns told reporters.

“It is just a dereliction of duty for him to stand up and say ‘It’s not my responsibility, it’s the commonwealth’s’… from 480 gigalitres to zero, that’s Niall Blair’s responsibility.”

Mr Minns also alleged the government planned to lower that 480 gigalitre threshold to just 80 gigalitres.

“No agriculture can take place in Menindee, little tourism and not much recreation and the government knows it,” he said.

AAP understands the government is yet to make a decision on lowering the threshold, and is holding consultations on the issue.

Premier Gladys Berejiklian was earlier forced to defend her absence from a Wednesday meeting between water authorities and regional mayors about the Murray-Darling crisis.

“They didn’t tell me they were here,” the premier told ABC radio on Thursday.

“I said to them ‘You should have told me you were in Sydney, I would have come down and seen you’, because no one told me they were here.”

The coalition on Thursday appointed a regional co-ordinator to oversee water supply to struggling towns in the region.