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Rain overnight in Wanaka has eased a situation where the plug appeared to have been pulled on the lake, but experts are still concerned about how dry it has been.

Two week’s ago, Wanaka Lake was the lowest it had been in almost 30 years, the Roys Bay grebe nesting platforms were within arm’s reach of land, and Bremner Bay was a rock garden.

Monday night’s rain was more than welcome as prior to that, the most recent big rainfall was February 19 but the town had sunshine for at least a month before and after that.

The triple whammy of drought, flash flood and drought in just three months concerned Wanaka freshwater ecologist Chris Arbuckle.

“I don’t want to be scaremongering, but it is a case of hell’s bells,” he said.

NIWA meteorologist Ben Noll of Auckland said, when contacted, that the country had experienced a summer of climatic extremes, while the lower South Island had been “very, very dry”, with very low inflows into lakes.

“The data we have certainly supports the impact you would have been experiencing on the ground,” he said.

“Our climate stations in Wanaka show in March, 29 out of 31 days were classified as dry days, less than 1mm of rain. That pattern has been repeated in Hokitika, Queenstown, Manapouri and Balclutha,” Mr Noll said.

The inflows into Lake Te Anau had been the lowest since 1926 and that spoke to the overall dryness in the region, he said.

Mr Arbuckle (56) told The Central Otago News he felt shocked and a little tearful after a weekend bike trip up the Matukituki River and saw the suffering of native fish and other creatures living around the edges of the lake and its rivers.

“It is not so much it is low, it is how quickly it has got low, and there’s not a lot of rain on the horizon,” he said.

While fresh water creatures such as eels were used to being disturbed by dry periods and having to find and compete for other homes, it was not so usual to have to adapt three times in three months, he said.

Their source of food also disappeared during dry spells, he said.

“If it continually happens, like humans, they get really stressed out. If this is what we have got to look forward to, whether it is climate change or uncertainty because of weather patterns, we are going to see the species we love go away,” he said.

Otago Regional Council water website revealed Lake Wanaka levels went from 276.6 in January to 278.1 on February 19 before dropping again to 276.3 by March 31.

According to ORC data, the lake was at its lowest since July 1992, when the level was 276.2.

“In my own memory I can’t think of any time it has got so low except in the ’90s. Talking to farmers, January was strange.

February got all the rain in 36 hours and then it was like someone had pulled the plug,” Mr Arbuckle said.

“We have had these things in the past . . . but I guess what I am sensing it seems to be happening more regularly . . . How much pressure is it putting on the ecology of the lake . . . [creatures] have had to look for places to find refuge twice in three months. We probably lost a lot of species precious to us in the tributaries,” he said.

While the shallow Bremner Bay was often used as a barometer of low lake levels, and it was usual to get the sandy parts exposed every year, “the thing that’s shocking is how quickly it has got low,” he said.

The only good thing was it had exposed some of the unwanted algae didymo to sunlight, which had killed it, he said.

Mr Noll said the extreme dry spells were something people would need to become used to
and resilience would be needed “from all walks of life”.

“We live in a warming world. With heatwaves, high temperatures and high evaporation rates . . . droughts develop more quickly . . . Climate change is influencing the weather we are experiencing,” Mr Noll said.

Queenstown Lakes District Council media communications officer Sam White said water
restrictions on the Lake Hawea supply came off at the end of January and restrictions in Luggate ended early February.

The council had fielded numerous reports of exposing rocks and other obstacles on Shotover, Kawarau and Clutha rivers, posing risks to navigation and safety.