Farmers believe more than $1 billion could be wiped off the value of the state's crops in the wake of the floods that are ravaging NSW.
The president of the NSW Farmers Association, Charles Armstrong, says government predictions of up to $500 million in crop losses are a significant underestimate.
"The true cost of the damage won't be known until people can get back in their paddocks and survey the damage," Mr Armstrong told AAP on Monday.
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"But I suspect (the figure of $500 million) is a significant underestimation."
It was possible up to half of the state's $2.5 billion wheat crop could be wiped out, Mr Armstrong said.
"This is devastating for farmers, particularly those who have had to deal with drought the longest," he said.
"It's ironic that after seven, eight, 10 years of drought we finally had a really good forecast of a bumper harvest.
"But that's Australia.
"It's happened before. It will probably happen again."
Mr Armstrong said he had spoken with both state and federal agriculture ministers about assistance for farmers.
"The real pressure for farmers is the debt hanging over their head, and the expense of the next crop," he said.
A spokeswoman for the Insurance Council of Australia said the NSW floods could not yet be declared a catastrophe.
It was not yet possible to estimate the possible cost of the floods to the insurance industry, she said.
Two key federal ministers will meet this week to discuss ways to assist farmers who have emerged out of a decade of drought only to see their properties flooded.
Attorney-General Robert McClelland, who visited Wagga Wagga on Monday, told reporters he planned to hold talks with Agriculture Minister Joe Ludwig this week.
"We are well aware of the fact that this community has done it tough, ironically with the drought over the last decade," he said.
"And for that reason there is primary producer assistance in place until early next year as a result of the drought.
"But I will also be having discussions in Canberra with Senator Joseph Ludwig in respect of the agriculture portfolio and we will certainly continue to monitor that situation.
"We are well aware that a number of farmers who were expecting a bumper crop are now ... suffering disappointment."
