The Save Tumbarumba Shire Group is campaigning for Wagga supporters to attend public hearings on Snowy Valleys Council boundaries as a new analysis put the cost of a demerger at up to $5.4 million.
The Local Government Boundaries Commission will hold hearings at Tumut and Tumbarumba early next month.
Tumbarumba small business owner Robert Blencowe said the anti-merger group was encouraging people from Wagga to support the argument that Tumbarumba had stronger ties to the city than Tumut.
"We know that there are a lot of people in Wagga who are very fond of Tumbarumba, they have come here for Tumbafest every year, they know how the place is going ahead," he said.
"We're letting it be known that if they feel strongly and want to support us, there is an opportunity and they can write a submission before the 13th of November.
"Hopefully with a bit more support from outside the region, the state government might look at this and realise there's huge support to be demerged."
Save Tumbarumba Shire has been protesting since the forced amalgamation with Tumut Shire in 2016, regularly appearing with orange uniforms and signs at public events whenever government leaders are due to appear.
The group has claimed Tumbarumba has fewer services and less of an ability to make decisions in the council as a result of the amalgamation.
The Commission this week released the "key findings" of a financial analysis of Snowy Valleys Council that it had commissioned from Deloitte Touch Tohmatsu.
Commission chairman Bob Sendt said the key findings were released so that ratepayers and residents would have a better understanding of the financial advantages and disadvantages of the proposal to "demerge" Snowy Valleys Council.
"Although the financial advantages and disadvantages of the demerger proposal are only one of the nine factors the Commission takes into account in examining the proposal, this factor is key to understanding the ability of the existing council and the proposed demerged councils to provide an appropriate range of services and how those services would be financed," he said.
The findings stated that "to date, [Snowy Valleys] has not realised economies of scale or net savings as a result of the merger. However, this is not inconsistent with the pre-merger modelling which assumed minimal if any savings in the first four years due to integration activities and staffing protections."
The Deloitte findings noted the council's "reliance on capital grants to maintain adequate investment in asset maintenance and renewal" but this was "consistent with many other rural and large rural councils".
Deloitte predicted a demerger cost "in the range of $1.6 million to $2.3 million for Tumut and $2.1 million to $3.1 million for Tumbarumba" that "in the absence of specific funding, would need to be borne by the community".
Save Tumbarumba Shire leadership team member Dr Neil Hamilton questioned some of the techniques used by Snowy Valleys to represent its finances, such as including recurring grants in the operating budget surplus, but said the predicted cost of the demerger would be worth it.
"The conclusion is that the cost of a demerger is extremely small," he said.
"The demerger cost of between $3 million and $5 million seems to me to be a very good deal. They are going to lose $7.7 million this year alone ... you cannot have a functional council called Snowy Valleys that will work, it is not structurally capable of being sustainable."
Snowy Valleys mayor James Hayes said there were "no great surprises" in the financial analysis.
"They haven't pulled any punches, but that's the way we like it. We don't want people beating around the bush, we want the facts," he said.
"It's a difficult process, a demerger. It certainly shows the state and federal government have got to support councils more in their finances as obviously we can't do everything the community expects just based on rates.
Cr Hayes said Save Tumbarumba Shire's claim that the short-term costs of the demerger were worth the long-term gain was an argument about the "difference between price and value".
"If you really value something, you will pay for it. That's why people wear Cartier watches," he said.
Cr Hayes said some councillors had decided to speak at the public inquiry but the council itself would not make a submission.