Waitaki River group is opposing any reduction in the river's minimum flow in a water allocation plan set in 2005.
The Lower Waitaki River Management Society wants the Waitaki catchment water allocation regional plan, prepared by a Government-appointed board, kept intact as it comes up for review by the Environment Canterbury regional council.
Last week, it met Environment Canterbury and Lower Waitaki-South Coastal Canterbury Zone Committee representatives to discuss the plan review.
Society interim chairman Ian McIlraith said yesterday the most disturbing aspect was the proposal to effectively lower the minimum flow in the present plan by 30% - from 150cumecs to 105cumecs.
The aim was to continue to provide 100% reliability of water supply to existing irrigation schemes, but the society disputed lowering the minimum flow was needed to achieve that.
South Canterbury hydrologist Frank Scarf had demonstrated reliable water could be provided to meet full irrigation demand on top of the existing 150cumec minimum flow in the plan, with a minor adjustment by Meridian Energy Ltd, which owns the Waitaki dams.
All that was needed was an adjustment between 0% and 0.5% through the dams, not putting the river at further risk.
The society said it was crucial to remember that expert opinion representing all river interests was heard by the 2005 board members prior to the minimum flow of 150cumecs being set.
"River flow needs for power, irrigators' consented water takes, safe bird and fish habitat, adjacent wetland water levels, connectivity to side streams, water quality aspects and what local people love about the Waitaki, were taken into account.
"Because of the growing pressure on the river, there is a strong feeling in the society that if we don't make some effort to uphold that plan now, erosion of river values will just continue," Mr McIlraith said.
Meridian's resource consents for its Waitaki generation system come up for renewal in 2025, and the society was concerned the zone committee was proposing Environment Canterbury's discretion should be limited when reviewing the consents.
The society considered the generation company's control of the river was already huge and deeply entrenched.
"The society can see no sense in volunteering yet more, especially when the Waitaki generation companies are proposed for partial sale," Mr McIlraith said.
The society was optimistic the zone committee would seriously re-examine these and other questions raised by it and there would be further direct discussion before recommendations were confirmed.
