The work was expected to be completed by late 2012, with the dam to be transferred to the Tablelands Regional Council in mid-2013.
The State Government recently suspended the upgrade for the wet season, with work expected to resume in April.
But Irvinebank Progress Association president, Jeremy Short, says work is unlikely to be finished until June.
"We've had absolutely no rain to talk of as of yet, but when we do get the rain I've been advised that the dam will only be able to be filled to about 25 per cent capacity, which is six metres below spillway level until they finish the dam," he said.
He says the association is worried residents will have to face paying for water to be trucked in because of delays in a upgrade the dam.
Residents have been restricted to 300-litres of water each per day, trucked in and paid for by the State Government since the work began.
Mr Short says he is concerned that will have to continue once the State Government transfers ownership of the dam to the Tablelands Regional Council.
"Council won't be able wear that burden, so it'll throw back on the community, which will probably work out about $100 to $125 per week per household to have that water trucked in.
"It's a big cost to the community and I doubt they'll be able to wear it."