River Murray irrigators can now access 81 per cent of their water entitlements, up from 74 per cent, the Department of Environment and Water has announced.
River Murray water delivery manager Jarrod Eaton said rainfall and inflows into the river system had permitted the allocation increase.
"Information provided by the Murray-Darling Basin Association (MDBA) shows a 50-gigalitre improvement over the past fortnight," he said.
"The MDBA-controlled storages have remained steady at 45 per cent capacity ... even with water being released to meet water requirements in New South Wales, Victoria and South Australia and for environmental purposes along the length of the River Murray system.
"We remain confident that water allocations will continue to improve over the coming months."
Still, just 530 gigalitres flowed into the river system during August, about one third of the long-term average.
Mr Eaton said that trend was likely to continue, and he hinted for the first time that opening allocations could be less than 100 per cent again in 2020.
The department will provide another update on October 1.