A prominent New Zealand freshwater ecologist has criticised the process of developing minimum flows for rivers around Central Otago, saying there is “nothing natural about a steady flow”.
Following a presentation in Wanaka last week, Massey University ecology and environmental science senior lecturer Dr Mike Joy said large fluctuations in flow rates were natural and were important in shaping and developing rivers over time.
His comments come as the Otago Regional Council works to develop minimum flow rates for a number of catchments in the area, including the Cardrona River.
“There’s this imaginary idea that there’s this excess amount of water in a river that you can take away.
“But in reality there’s not – there’s no such thing – because excessive flow is what shapes the river, it’s what washes away all the crud out of the river, it’s what shifts the sediment, it’s what opens the bar at the end and all that kind of stuff that’s crucial to the life of the river.
“They seem to think it’s all spare except for this tiny little bit that’s left there.”
River health related to more than just the animals living in it, he said.
River geomorphology, or the change of river channels and shapes over time, would be affected by reducing flow rates, he said.
“It’s evolved over time – the shape, the valley, everything – it’s evolved over time to those natural flows.
“The river’s been there a million years and we’re doing it in a blink of an eye.”
Developing minimum flows placed potential farming profit ahead of everything else and the “winner’s always the one with the most money”, he said.
A crucial point was that councils were not independent in the process, he said.
“Regional councils and district councils are not independent in any way.
“Their jobs are dependent on there being farmers making lots of money. More farmers, more growth, keeps them in jobs.
“The Resource Management Act is supposed to be avoid, remedy, mitigate – in that order.
“There’s never any avoid.”
In September last year, a group of Tarras farmers in the Lindis Catchment Group appealed the ORC’s decision to impose a minimum flow of 900 litres per second in the Lindis River.
Mediation talks between the farmers, council and other affected parties were unsuccessful and the case will now be decided in the Environment Court next year.
Central Otago farmers have raised concerns that the process will now set a precedent for other negotiations, while environmental lobby groups, including Fish and Game, have also spoken out against the process.
At the Central Otago Environmental Society annual meeting on Friday, committee member Graye Shattky said the advocacy group had been “surprised and disappointed” to learn the ORC had later agreed to a 550-litres-per-second rate through discussions with the Lindis Catchment Group.
The environmental society, along with other affected parties, maintained support for a 900-litres-per-second minimum flow, but were now forced to “defend the proposal against the proposer”, he said.
Council planning director Tanya Winter said councils were required to develop environmental flows and levels, encourage efficient use of water and manage water within limits under the national policy statement for freshwater management.
Rivers did require fluctuations to remain healthy, and these were provided by floods and increases in water flows following rain, she said.
“The water plan for Otago provides for the setting of minimum flows and allocation limits and we do this with overall intent of maintaining sustainable water flows and limits.
“The main mechanism that council can use to manage the effect of irrigation on flow variability is allocation limits and these are set as part of our minimum-flow plan-change process.”
The council always maintained an independent approach in setting minimum flow rates, informed by a combination of science, economic and social assessments as well as community input, she said.
“We also meet the requirements set out in the Resource Management Act.”
The RMA was about sustainable management and included a number of principles, she said.
“It is not appropriate to consider one of those principles in isolation.