A review of the way water is allocated in the lower Waitaki River has been challenged by a Waitaki River watchdog group.
The Lower Waitaki River Management Society wants the review withdrawn or put on hold until questions it has raised about the analysis of river flows have been answered.
Its request has been directed to the South Canterbury Coastal Zone Committee, a joint body of community, Environment Canterbury (Ecan), Waitaki and Waimate district council representatives, which is considering the review.
The Waitaki catchment water allocation regional plan was drawn up in 2005 by a Government-appointed board during controversy over Meridian Energy's Project Aqua proposal. It sets in place the way water from the lower Waitaki River is to be allocated, and minimum flows.
The Lower Waitaki River Management Society's board recently met representatives of the zone committee and Ecan to receive feedback on concerns it raised more than a year ago about the proposal to lower the minimum flow from 150 cumecs to 105 cumecs over the summer period.
The society had said at the time it wanted a 100% reliable supply of above 150 cumecs from Meridian for all main stem irrigators, so that priority irrigation rights could be met.
''Our technical advice is this is perfectly feasible and we are asking the zone committee to confirm that,'' society chairman Ian McIlraith said.
Until then, it wanted the zone committee to withdraw or delay any support for the change.
The society was not happy with a report by Ryder Consulting on the impacts of changes, which it said was flawed.
Any flaw in hydrological assessment would throw the assessment of environmental effects into doubt and could misrepresent the ability Meridian had to release water to meet irrigators' needs. The society outlined the issues and how they might be resolved at its annual meeting yesterday.
The plan review is to be publicly notified for submissions from November 9 to December 6.
Further submissions would be sought early next year and the plan change heard by independent commissioners in the first half of 2014.
