If the forecast comes true, Wagga's gross domestic product will shrink by more than $311 million down to a total of $3.4 billion.

Consultancy firm SGS Economics and Planning has predicted that businesses within the Wagga City Council area could also fare slightly better than the national average with minimum fall of five per cent compared to an Australia-wide 6.7 per cent.

SGS principal and partner Terry Rawnsley told The Daily Advertiser that Wagga having a more diverse economy, with less reliance on face-to-face services and tourism than other areas, could reduce the impact.

"For Wagga, with its agricultural base, when things get back to normal it should start to swing back to growth quicker than some other areas of the country," he said.

Wagga's forecast GDP decline was similar to the national fall seen during the early years of the Great Depression, but Mr Rawnsley said there would not be the same social conditions.

"With the wage subsidies being pumped into the economy, we will probably avoid a depression...the economy will bounce back but probably not to where we were last year," he said.

Lockhart, Coolamon, Temora, Junee and Snowy Valleys council areas were forecast to see less of an economic impact than Wagga.

The pre-merger Gundagai council area as well as Albury City and Federation council areas were forecast to fare worse with declines between 7.5 and 10 per cent.

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NSW Business Chamber Murray-Riverina regional manager Andrew Cottrill said forecast from SGS and the Reserve Bank showed that is was important to get people back into work and normal routines as soon as possible.

"We will be looking to governments to help stimulate the economy again through marketing campaigns and easing the red tape on businesses so we can encourage investment and jobs growth in our region," he said.

Mr Cottrill also credited agriculture with helping to keep the region's economy "afloat".

A new federal Parliamentary Library report warned that 38 per cent of casual workers had been with their current employer for less than 12 months and might not be eligible for JobKeeper wage subsidies.

The report found that 26 per cent of the 80,400 workers in the Riverina electorate were employed as casuals.

"The question is how many of those workers will miss out on the JobKeeper program and that is a point of confusion for everybody," Mr Rawnsley said.

"If the bulk of the casuals are under JobKeeper then that will help the economy back up but if more of them miss out then it puts another challenge in front of the recovery as they will fall back on JobSeeker and not have as much money in their pockets."

JobKeeper is a $1500 per fortnight wage subsidy paid via employers whereas JobSeeker is a temporarily doubled unemployment welfare payment of $1100 per fortnight.

The SGS report used data from the Australian Taxation Office's Single Touch Payroll system, which has allowed faster monitoring and publishing of employment statistics during the coronavirus pandemic.

SGS compared the known reduction in people employed and work hours in different industries across Australia to the type of businesses in Wagga and estimated the region's economic damage from bushfires and emergency health orders.