Otago Regional Council staff would be closely monitoring irrigation in all the catchments affected by low flows and, as it had warned in late December when river levels dropped, any illegal irrigation found could result in enforcement action, council group manager of regional services Jeff Donaldson said.
Most Otago rivers had risen again to normal levels in mid-January after a fortnight of colder, wet weather and a heavy thunderstorm in Central Otago put the Clutha catchment into flood late in the month.
However, since then hot, dry weather had predominated, with only two rainfall sites around Otago recording more than 10mm of rain and many not receiving more than 1mm, the council's rainfall and river report for January 28 to February 3 showed.
About 11 sites recorded no rainfall, including Middlemarch; Clifton Falls, north of Oamaru; Hills Creek, in Central Otago; Kelso; and Dragonfly, in the hills above Wanaka.
As a result, river levels dropped at all sites around the region, with only three - Dunstan Creek, at Beatties Rd; the Pomahaka, at Burkes Ford; and Waipahi - remaining in the normal flow range, the report said.
"The remainder fell below normal and in the case of both the Kakanui River, at Clifton Falls, and the Taieri, at Outram, well below normal."
The low flows saw alerts registering on the regional council's "water info" website on the Kakanui, at Clifton Falls Bridge; Mill Dam and McCones; the Taieri, at Sutton; Outram and Waipiata; and the Shag, at Craig River.
Mr Donaldson said as many of the rivers were at, or below, their minimum flow levels, resource consent holders had stopped or were now rostering their water use.
The Shag River had fallen below its minimum flow and water users should no longer be taking water, he said.
"It is likely that some reaches of the Shag River, below Dunback, are dry."
The Kakanui River had reached very low levels and irrigators were being reminded to "please keep a close eye on the council website to ensure levels don't drop any further", Mr Donaldson said.
Varying low-flow restrictions were also in place for the Waianakarua River and the Pomahaka catchment, which was in flood just a fortnight ago, was nearing minimum annual low-flow levels.
"Irrigators are advised to check the conditions on their resource consent to ensure they don't breach them."
Water abstraction from the Taieri River was dominated by deemed permits (mining privileges) so no minimum low-flow levels applied, but those farmers who did have resource consents needed to adhere to them, Mr Donaldson said.
"If flow levels continue to decrease, the council may issue lawful directions that water takes authorised by all permits, including deemed permits, must be stopped."
