The independent report into the Lower Darling fish kill is in and the Commonwealth's coffers are bracing for a multi-million dollar hit.
The federal government now is moving to buyout the controversial A Class water licences in NSW's Barwon Darling catchment of the Murray Darling Basin.
The buyout bid could exceed $20 million. The total A Class volume is 9 gigalitres and average price was around $1500 a megalitre back in 2018, when drought was only starting to bite.
Cotton grower Bengerang Limited holds the majority of A Class entitlement and it's understood it and other potential sellers are open to buyout discussions with the government.
These licences are so valuable because not all water is equal in irrigation country. A Class was created by NSW government in 2012 to provide irrigators access during times of low river flow.
A key recommendation from the report was to safeguard low flows to prevent future fish kills because that's when water is most valuable to the environment as well as irrigation.
Low flows connect fish refuge waterholes, maintain healthy levels of dissolved oxygen and to keep the ecosystem at in a state where it can bounce back quickly when it rains again.
On top of the A Class buyout, Agriculture Minister David Littleproud also committed to spend $70 million, drawn from the $12 billion Basin Plan budget, on other fish kill prevention measures.
"I think all Australians who saw footage of these fish deaths were deeply saddened," Mr Littleproud said.
"The federal government accepts and will address each recommendation made to it, and will work with states on others."
The report was prepared by an expert panel chaired by Professor Rob Vertessy, and found a range of factors contributed to the fish kill.
The report listed record-breaking drought; a sudden cold snap which exacerbated the low oxygen levels in a river pool below Menindee where fish were trapped, and; the management of the Menindee Lakes storage system which prioritised water releases to meet cross-border flow requirements into South Australia over storage for future dry spells.
The findings aren't just significant for NSW and Queensland. South Australia and Victoria are also impacted by Vertessy's call for a rewrite of the management regime of the Menindee Lakes.
The Far West NSW storage has traditionally been used as a priority water source to meet upstream states' water delivery commitments to SA.
This regime saw a vast amount of the unseasonable winter flood windfall, which filled Menindee in 2016, released to SA in 2017 and left the Lower Darling and its native fish high and dry when drought bit at the end of the year.
But in future, the report said, more water should be held back to maintain consistent low flows down the Lower Darling.
It remains to be seen how Mr Littleproud addressed the report's recommendation, but any changes that increase water availability to the Darling River raise the possibility that the Southern Basin, where communities are rallying against further water recovery, could be called on to plug the gap.
Around 9GL of the new A Class licence category was created by then NSW Water Minister Katrina Hodgkinson in 2012. They were designed to provide increased access to water during low flows.
Previous rules required a flow rate of more than 1000ML/day over the Bourke Weir before licence holders could pump, but A Class holders can pump when the weir flows at more than 350ML/day.
Bengerang, run by the Robinson family, acquired its entitlements in August last year when it split from a joint venture with Webster. It paid $134 million for the JV's northern cropping and water assets, including an aggregation at Garah and Darling Farms at Bourke.
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