Rotorua councils warn of record low streams, possible water restrictions

The Ngongotaha Stream is at its lowest in many years. Photo / Andrew Warner

Rotorua streams have been at record low levels, with water restrictions increasingly likely if significant rain doesn't fall in the near future.

Speaking before this weekend's rain, Bay of Plenty Regional Council water shortage event manager Steve Pickles said many of the monitored streams were hitting lows not seen before after three "very dry summers".

While Rotorua Lakes Council was not experiencing any source water issues for now, it was keeping a close eye on the stream levels and their potential impact on water supply.

Pickles said the state of several local stream levels meant there was "a higher chance that restrictions may be imposed for some parts of the region over the coming months".

"This all depends on any future rainfall."

Whether this weekend's rain had any impact is not yet known. The Metservice reported 84.5mm fell in Rotorua between 10am Sunday and 3pm Monday.

A Niwa seasonal climate outlook released last week for the Bay of Plenty predicted a 40 per cent chance of "normal" rainfall and a 35 per cent chance of "above normal" rainfall between February and April.

The report also referred to "extremely dry conditions" in the Western Bay of Plenty, Auckland, Northland and Waikato during January.

In January, the regional council issued a level 1 Water Shortage Event, affecting streams within the Rotorua Focus Zone and those with their headwaters in the Mamaku Range.

"Unless we receive significant rainfall we expect to move those streams into level 2 of a Water Shortage Event in the near future," Pickles said.

There are four Water Shortage Event alert levels: alert level 0, meaning no water shortage concerns; alert level 1, meaning reducing water availability; alert level 2, meaning impending water shortage; and alert level 3, meaning water shortage event.

Water restrictions will only happen if Rotorua reaches alert level 3.

The Rotorua Focus Zone, in which several streams are being monitored. Image / Supplied

Under alert level 1, the regional council was undertaking additional flow measurements in affected waterways, increasing assessment, analysis and reporting for the focus area, while also increasing communication with affected people.

Pickles said water users need to prepare and plan for water restrictions if the dry weather conditions continued.

"Commercial, horticultural and agricultural water users will need to start thinking about how they can manage operations with lower water use now, in case water restrictions have to be implemented later this season.

"However, this isn't just a consideration for our rural community - urban users will also have to start thinking about how they can reduce their water demand during the summer months."

Pickles said the organisation kept a "careful watch" on the streams that made up the Rotorua Focus Zone since last year's dry summer. The streams replenished a little over last year's cooler months but "over recent weeks several of the streams in the district have dropped down to low flows similar to last year's event".

"We will need a period of prolonged rainfall in order for the stream flows to recover to pre-2020 flow levels."

Unpredictable weather caused by climate change meant the region was more at risk of both droughts and floods in the future, he said.

Planning for and reducing the impact of climate change was one of the regional council's top priorities, he said.

Rotorua Lakes Council manager of infrastructure Networks Performance Eric Cawte said the organisation could not recall the last time it imposed water restrictions.

"We can say there have been no restrictions put in place for at least the past decade. At times it has been necessary to ask residents to minimise water use due to increasing use or while work is carried out on infrastructure, but again there have been no formal restrictions," Cawte said.

Most of Rotorua's drinking water supply was sourced from underground springs so short-term weather changes did not generally have a significant impact.

"However, the rate at which our community uses water can impact our ability to maintain supplies, so it is always important for our community to use water sensibly with the wider impact on the environment and infrastructure in mind," Cawte said.

"All of the springs that provide our drinking water also supply natural watercourses such as the Utuhina, Puarenga, Awahou and Hamurana streams. Ensuring that our community conserves water where possible helps to ensure that the impact on those watercourses is kept to a minimum."