A report on the Manuherikia River has been delayed and it will now be nearly a year after calling for the work to be done before Otago regional councillors see it.

Once complete, the report, from the Manuherekia Reference Group’s technical advisory group (Tag), should confirm what effect different irrigation season minimum flow settings would have on the health of the river.

Tag’s report was originally supposed to be presented to councillors in March.

Deputy chairman Kevin Malcolm, the council’s representative in the Manuherekia Reference Group, said the missing information had “completely clouded the decision-making process” for the council.

He had first been told Tag’s scientific work was complete in February last year, before the community was consulted on proposed minimum flows.

Cr Malcolm said he later learned it had not been done and consequently assumptions made in last year’s consultation were not yet backed by a robust process.

“This process may come out that every figure they put on the consultation paper is correct. That’s one thing that could happen,” Cr Malcolm said.

“Or they’re that far out that it’s not even funny.

“These are life-changing decisions for our communities. How can I take a punt on something that hasn’t been signed off as correct?

“Or if it isn’t signed off as correct, have an understanding of what those risks could mean . . . We were never given that.”

Otago Regional Council policy and science general manager Anita Dawe said staff hoped to schedule a late June or early July meeting of Tag members.

The group included council staff and representatives from Aukaha, Otago Water Resource Users Group, Omakau Area Irrigation Company, Otago Fish & Game, and the Department of Conservation.

If the next meeting went ahead as hoped, it was likely the final Tag report would be brought to an August 10 committee meeting.

The council needs to set minimum flows for the river in its land and water plan, due at the end of next year. But when councillors were asked to note minimum flows for the Manuherikia last year, in a 6-5 vote they opted not to.

Instead, during the four-and-a-half-hour discussion at the August 25 council meeting, they argued over whether there was a “robust, fit-for-purpose and defendable rationale” underpinning the proposed minimum flows.

Some said there were still gaps in the science. Others accused their counterparts of delay tactics and questioned their integrity.

In the aftermath of the meeting, then-Cr Marian Hobbs signed a petition urging Environment Minister David Parker to disband the council and install commissioners. She later resigned.