According to a discussion paper from the forum, the cost to the councils to fund the remaining $60 million equates to an average rate increase across the region of around 1.3 per cent, with expected direct and indirect returns on the investment being between $947 million and $1.7 billion.
Carterton Mayor John Booth said the extension was something that needed to be done together as a whole region and the forum agreed unanimously to support the proposal.
"We all agreed how the funding would be worked across the Wellington region."
"Wellington City Council would be putting up the vast amount."
He said a discounted formula would be used to calculate any Wairarapa contribution because it was further away.
He said there were exciting possibilities resulting from using newer, larger aircraft.
"It's not just about passengers, it's also about the potential for freight."
"When the Wairarapa Water Use Project comes into being, there's going to be increased availability of different products that will need to be exported."
The extension would allow larger aircraft to take more products to the US and Asia, he said.
Masterton Mayor Lyn Patterson said no funding commitment had been made by Masterton District Council and it was not in its long-term plan.
"It's an agreement in principle, it hasn't even been discussed at our council," she said.
She supported the project and said the tourism industry in Wairarapa would benefit.
"The more people that can come here, the more people it brings to Wairarapa."
"Anything that increases the number of people will have a spinoff for us."
The rest of the project is to be funded by Infratil, which owns two thirds of the airport, and possibly the Government.
Resource consent applications will be lodged later this year, after public consultation is carried out.
South Wairarapa Mayor Adrienne Staples was not available for comment.
