Information on the proposed Tarras irrigation scheme's "purpose and outcomes" will go out to the public alongside the Otago Regional Council's proposal to invest in it.
The move was suggested by Cr Michael Deaker. He had questioned the lack of detail in the proposed long-term plan amendment to tell the public why the council would want to invest in the scheme, and how the scheme would affect the Lindis area.
"Not a sales pitch, but the rationale to go with this very intense business analysis."
While most councillors agreed to put the investment proposal out to the public, some still had reservations about the council's role in the scheme.
Bryan Scott said he questioned the need for the council to be involved to the extent it was proposing. Investing $3.5 million in shares and possibly up to $3.2 million in fixed costs would have a direct impact on rates, he said.
He suggested it was possibly a better fit for council-owned Chalmers Property.
"It's one step too far, in my view. I'm concerned about precedent."
Cr Doug Brown said he was concerned that investing was a conflict of interest with the council's role as regulator.
Cr Gerry Eckhoff said the benefits from the proposed irrigation would be inter-generational and history told him that no significant irrigation scheme in Central Otago had been commissioned without public money.
Cr Trevor Kempton said it was the best "win win" situation he had seen in his two years on the council.
While it was considered "high risk" compared to the council's usual investment proposal, it would not be by a venture capitalist, he said.
Putting the proposal out for consultation gave the council more time to collect the information it needed before it made the final decision.
Chairman Stephen Woodhead said it was a very complex water management catchment which provided the council with a unique opportunity.
Cr Duncan Butcher said the reasons for the council's involvement in such a scheme could be found in its regional policy statement and its proposed water plan, but it did need to be explained.
The council approved the proposed amendment going out for public consultation, with submissions closing on December 10.
A hearing would be held in late January with the panel comprising councillors Sam Neil (chairman), Brown, Louise Croot, Eckhoff and Mr Woodhead.
