The Otago Regional Council (ORC) is encouraging people using irrigators, as well as other water users, to be mindful of the conditions as New Zealand enters a La Niña summer.

La Niña, which can happen every three to five years, arises due to changing temperatures in the Pacific Ocean.

For central and western parts of the lower South Island, a La Niña summer means drier conditions and a higher risk of drought.

The last La Niña in 2017-18 came with a freak marine heatwave that set the stage for New Zealand's hottest summer on record. In Otago, drought had a devastating impact on farmers’ crops and their stock.

ORC regulatory general manager Richard Saunders said people need to be responsible about their water use going into this summer.

“Dry weather means less water in rivers and races, so anyone taking water needs to be mindful of their consent conditions and responsibilities and to actively monitor how much water they are taking,” Richard said.

“Depending on the impact of La Niña, that could become important for avoiding restrictions on water takes in the coming months.”

He said people using irrigators have worked together to share available water during low flow events in the past, and “we would hope to see that repeated over this summer if waterways start to run low,” Richard said.

Organisations tracking weather said in October that La Niña had arrived in New Zealand.

It is one of the three phases of the weather occurrence known as the El Niño-Southern Oscillation (ENSO). This includes the warm phase called El Niño, the cooler La Niña and a neutral phase.

While La Niña usually means wetter summers for the northern parts of New Zealand and windier weather on the eastern coasts, southern and inland areas experience less rain on average.

Live water flow information can be found online here.

Contact the ORC on 0800 800 033 if you have observed low flows that may be affecting freshwater plants or animals.

PHOTO: Supplied