Otago Regional Council staff have recommended returning the flow of the Manuherikia River to its natural state — but not for 17 years.
After an explosive decision not to note minimum flows two years ago, regional councillors will tomorrow revisit proposals for rules for water users in the Central Otago catchment.
The proposed changes for the forthcoming land and water plan would likely require significant infrastructure changes and could precipitate large-scale changes in farming or land use in the area.
Yesterday the staff recommended minimum flows for the Manuherikia were made public after long-delayed hydrological and ecological reports were presented to councillors last month.
"It’s important to note that the Manuherikia River itself needs time to adjust to new flows," Mr Saunders said in a statement yesterday.
"The science tells us that a significant jump in flows creates its own ecological risks.
"Based on the significant work done to date, staff are recommending that the Manuherikia’s minimum flow level should reflect where a river’s range naturally sits.
"We see the 17-year timeframe as being change at an inter-generational pace, so the necessary steps can be taken to effect that change successfully.
"Regardless of the final limits set in the plan we need to support all the landowners and the broader community to help achieve the target."
The staff report to be presented to councillors tomorrow said since the August 2021 meeting when councillors asked staff to "finalise the required science" for a proposed minimum flow regime, about 1400 hours of staff time and $417,000 had been spent.
At the 2021 meeting, the staff recommendation for Campground was 1200 litres per second by this year, 1500 litres per second by 2030 and 2000 litres per second by 2037.
Now, though staff have proposed implementation of a minimum flow of 900 litres per second from when the council’s land and water plan is notified next year.
That would increase to 1200 litres per second by 2030, and ultimately to 2500 litres per second by 2040.
The recently completed hydrology work, presented to councillors last month, showed in a natural state, the river at the Campground site would never have dropped below 2000 litres per second from 1974 to 2020.
It would have dropped to 2500 litres per second about once every 25 years.
Tomorrow’s staff report said economic studies included in their recommendation identified that farmers and growers were "facing complex challenges that would be exacerbated with reduced irrigation reliability".
"At a catchment scale, the work identified a steep reduction in profitability for all farm types, but sheep and beef farms are the most at risk."
However, staff said those studies were all based on the sudden imposition of a higher minimum flow, rather than introducing a higher minimum flow over time.
Farmers last month said the flow levels suggested by the scientific studies could devastate the economy of the community that relied on the river.
Mr Saunders said subject to tomorrow’s decision by councillors the Manuherikia flows would be included in the council’s land and water plan consultation and would be discussed at community meetings at Ophir next month.
