In its decision, the board of inquiry ruled that the amount of groundwater permitted to be taken from the Ruataniwha aquifer could be increased from the current level of 28.5 million cubic metres per year to 43.5 million cubic metres per year.
The board said it accepted scientific evidence that "tells us that this is a sustainable yield and it supports the economic wellbeing of the rural community" provided "adverse effects on surface flows are adequately avoided, remedied or mitigated".
Regional councillor Rick Barker told a council meeting yesterday he was "intrigued and surprised" to learn second-hand about HBRIC's application to take the water, which it lodged in May.
At yesterday's meeting he asked that reports on the application be prepared by council chief executive Liz Lambert and HBRIC.
"It's a really interesting thing that here we have the regional council, through its investment arm, taking a predominant position on the allocation of water in a particular region. I think this is really quite unusual.
"I'd like us to have a discussion about it," Mr Barker said at the meeting.
HBRIC chief executive Andrew Newman could not be reached for comment after the meeting. Mrs Lambert said the proposal had been discussed with the Ruataniwha Water Users Group ahead of the consent application being lodged and the group had also been advised once the council received the application.
"There was nothing secret squirrel about it," she said.
The chief executive of Irrigation New Zealand, Andrew Curtis, said taking groundwater provided "an opportunity for a different type of distribution system" as part of the Ruataniwha scheme.
"Once they've worked out where they're going to irrigate, they've then got to work out what is the most cost-effective distribution system to get the water from the dam," Mr Curtis said.
Meanwhile HBRIC said yesterday it would not appeal against the board of inquiry's decision.