The union was in a delicate situation financially and Mr Mains, who joined the board two years ago, said "less than responsible" decisions made at the time Carisbrook was sold were coming back to haunt the current board.
ORFU chairman Wayne Graham this week described the union's finances as "very tender" and expected it would post a loss for the past financial year.
The Otago Daily Times has also seen an email he sent to club chairmen this week in which he said "many years of poor decision-making have come to the fore and we are now in an extremely delicate situation".
Mr Mains said he first heard of the union's debt from selling Carisbrook when he joined the board, and since then it had been working hard to clear that debt.
"It is not going to be easy, but this board is mindful to meet its current responsibilities. It would be easy to walk away and go into liquidation and start again, but we don't want to do that."
Mr Mains, who is standing for re-election on the board next month, said that after the Otago Rugby Football Union sold Carisbrook to the Dunedin City Council for $7 million in August 2009, the union ended up with a debt of $1.2 million after repaying a $2 million loan to the council.
The union was now being forced to pay off the debt.
"It was a less than responsible decision made by people at that time and not just the board of the ORFU. I've been in business an awful long time and there is no way I would have agreed to that situation."
Board member Andrew Rooney said yesterday board members had put in significant time, effort and finance to help out Otago rugby over the past year and admitted finances were at a delicate stage.
None had formally put in their own money but many had given money through fundraising and organising events.
The union was not seeking public contributions but was looking at options.
Asked if it was a bleak situation, Mr Rooney said: "I'm reasonably optimistic we can work through it and get things done. It is not all doom and gloom."