Setting a minimum flow for South Otago's Tuapeka River might seem surprising but no-one knows what the future may hold, Otago Regional Council chairman Stephen Woodhead says.
The regional council has begun the process of looking into a minimum flow for the river beginning with a report on what flow levels are needed to ensure its threatened fish species, such as dusky and Clutha flathead galaxias, and significant trout fishery thrive.
A tributary of the Clutha River, the Tuapeka is located 70km west of Dunedin.
''It's an important little river,'' Mr Woodhead said.
It was good to be considering flow levels in the river before any pressure was put on it in the longer term, he said.
''It's an area of Otago you would not think needs a minimum flow but you do not know what is coming in the future.''
Council hydrologist Lu Xiaofeng said in a report to the council's technical committee recommended flows to retain suitable levels of habitat during the irrigation season had been suggested for existing fish species in the lower reaches of the river.
''Trout spawning occurs in winter, making it a significant value during winter months.''
The optimum flow for trout spawning habitat was 420 litres per second.
At the moment 19 litres per second was allocated from the catchment, for the Tuapeka rural water supply scheme.
Analysis had shown that suggested management flows would not reduce the security of supply for the supply scheme, he said.
The report would be used by the council when consulting the community in the future when setting a minimum flow.
