Changes are needed to the Waitaki water allocation plan to ensure the multitude of benefits to the community from the lower river can continue in the future, the Waitaki Irrigators' Collective Ltd believes.
The group supports the changes, including a lower minimum flow for the river.
Its policy manager, Elizabeth Soal, said although many people believed the river was managed according to the plan, in reality some of its crucial parts could not be implemented.
That was due to fundamental conflicts between the plan's provisions and a consenting environment ''out of step'' with it.
''Fundamentally, the plan sought to provide certainty for all water users - hydro-electric, recreational, environmental, cultural, agricultural, community and stock drinking water, and other uses,'' Ms Soal said.
''Unfortunately, some key components of the plan just don't work.''
Two examples were no mechanism to compel compliance with some of its provisions, and resource consent holders being disadvantaged in the future when it guaranteed them priority and protection.
She assured people what was happening now on the river would not change; its average flow would remain about 360cumecs. Lowest flows would happen during winter, outside the irrigation season.
''It has always been a part of the plan that in times of very low inflows, the river will run more closely to its natural state, as it would if the flow wasn't controlled by the hydro installations upstream,'' she said.
The lower minimum flows in the plan change were necessary to ensure the community was not subject to the boom-and-bust nature of droughts that plagued it in the past.
''We believe the plan change will provide all parties with the certainty they need for the future, while allowing the river to function in a healthy way.''
Irrigators in the Waitaki had made huge improvements in water-use efficiency in recent years, so much so, they were voluntarily reducing the amount of water allocated to them by ''a fairly large amount''.
Regional plans under the Resource Management Act generally had a life of 10 years before they were reviewed, so the timing of the Waitaki plan change was ''quite normal'', she said.
