A new report by a policy think-tank organisation is pointing the finger of blame for the Darling River fish kill towards the management of the river system.
The Australia Institute research says the Menindee Lakes were drained in 2016-17 and not sufficiently replenished by further flows.
‘‘It is clear what has caused the Darling River fish kill — mismanagement and repeated policy failure,’’ The Australia Institute senior water researcher Maryanne Slattery said.
She said the lakes were drained by the Murray-Darling Basin Authority, which is directed by the state governments.
‘‘Claims NSW could not have influenced the MDBA’s actions are false.
‘‘The water level in the lakes is not being replenished by regular smaller flows. While large floods still reach Menindee, regular small-medium flows have decreased dramatically.
‘‘MDBA research highlights an irrigation development in the northern basin as playing a key role in reducing these smaller, regular flows, along with drought and climate change.
‘‘To blame the fish kill on the drought is a cop-out, it is because water releases were made from the lakes when this simply shouldn’t have happened.’’
However, Australian Academy of Technology and Engineering water forum chair Professor Rob Vertessy said the operating procedures for releasing water from the Menindee Lakes were established in the late 1960s.
‘‘The rules are clear and transparent. The lakes are drawn on before other storages in the system because the evaporation rates are very high and it is inefficient to store water within them. Evaporation from the lakes is around 430Gl for an average year and could be up to 700Gl per year when the lakes are full.
‘‘The releases over the recent two years were not exceptional — in fact, for a while the rate of release was reduced to support a major cod breeding event in the area.
‘‘The big problem has been very low rainfall in the northern basin over the last two years and thus very low inflows. Since the lake levels last peaked (in December 2016) there has been only 140Gl of inflow to the lakes and about 900Gl of evaporation.’’
Menindee sheep grazer Rob McBride said: ‘‘What every Australian needs to understand is that this is an ecological catastrophe created by the governments implementing the Murray-Darling Basin Plan.’’
‘‘This confirms what our Barkandji people and others living along the Baaka/Darling River have long known: we are being made to pay the price for over-allocation of water upstream,’’ Barkandji elder Badger Bates said.
Professor Vertessy said it was unfair to criticise the MDBA for applying a long-standing agreed release procedure.
‘‘Having said that, in view of the severity of the fish kills and the changing reliability of inflows into the lakes system, it would be appropriate to review the lake operating procedures.
‘‘To date there have been limited investigations into the changing reliability of river flows in the northern basin, but it is evident that climate shifts and catchment development have changed how the system behaves.’’