A drier and warmer December than normal has resulted in low levels in some Otago rivers.
Otago Regional Council’s (ORC) data for October - December 2017 shows extremely dry weather conditions in Central Otago and part of South Otago, while the rest of Otago experienced moderately dry conditions.
ORC director engineering, hazards and science Gavin Palmer said some areas had particularly low rainfall and the current spell of dry weather, combined with little snow cap to augment river levels from snow melt last year, means most Otago river levels are low compared to average levels for this time of the year.
The Taieri River and Kye Burn hit record low levels last month – the Taieri River’s Canadian Flat site level in December was the lowest since records began in 1982 and the Kyeburn was the lowest since records began five years ago. The Kakanui River was also much lower than normal at 57% less than its average flow.
“Some areas were very dry in terms of rainfall, for instance, December’s rainfall was only 15mm at the Shotover rain gauge, 33mm at the Kyeburn, and 30mm at Matukituki, compared to December averages of 77mm, 89mm and 75mm. Some areas received above average rainfall though, for example, one site near Dunedin received 37% more rainfall than its normal December rainfall of 35mm,” Dr Palmer said.
The aquifers monitored by ORC were very low in December in Hawea Basin, Wakatipu Basin and Dunstan Flat in Central Otago. Aquifer levels were also low in December in South Dunedin and West Lower Taieri, and higher than average in North Otago, East Taieri, Roxburgh and Ettrick.
This week’s data (below) shows several rivers are at or below their minimum low flow level, which is the level agreed by the community and stakeholders to maintain the health of the river. The Lindis and Cardrona Rivers are dry in some sections.
North Otago farmers taking water from the Kakanui and Waianakarua Rivers have instigated voluntary water rostering as the rivers approach the minimum flow level. ORC is contacting stakeholders this week reminding them to actively monitor their takes.
“We’re reminding people who irrigate that some rivers are below minimum low flow levels and to be mindful of their water use consents conditions and responsibilities, and conserve water where possible,” Dr Palmer said.
According to NIWA, Otago’s weather is likely to be warmer than average over the next three months, with inland areas predicted to have above or near normal rainfall, while river flows are expected to be below or near normal.
ORC is continuing to monitor the situation and regularly updating flow information on the ORC water info site on www.orc.govt.nz or water info line 0800 426 463.
For more information contact:
Gavin Palmer
Director Engineering, Hazards and Science
Otago Regional Council
0800 474 082
gavin.palmer@orc.govt.nz
or
Sian Sutton
Director Stakeholder Engagement
Otago Regional Council
sian.sutton@orc.govt.nz