Transpower has said hydro lake levels had fallen to just 55% of average for the time of year, putting them in the bottom 5% of historical records.
But the rain over the weekend has provided some respite for the hydro lakes, and most generators say they are in a better position.
A Meridian spokesman was cautiously optimistic.
“Over the last 48 hours we had about 150mm into the Waitaki headwaters, and 100mm-120mm in the Waiau headwaters.
“It’s another welcome step in the right direction, rather than a game-changer, but we also have three more events coming later this week that will cumulatively also make a difference.”
Genesis Energy, which operates Lake Tekapo power station, said the rain had also provided some relief.
“Recent rain has seen the lake gain a little over 2% since Thursday, but the inflows are muted due to the catchment being dry beforehand and some of the water being stored as snow.”
“There is also more rain forecast for the catchment over the next fortnight.”
Contact Energy’s response was muted.
“Our consent conditions for the Clutha catchment lakes allow us to access a two-metre range between 336 and 338msl (metres above sea level) for electricity generation. However, we are not expecting to access this range,” a spokeswoman said.
“Rainfall over the weekend was less than forecasted but has resulted in a 20cm rise in the level of Lake Hawea, with more significant rain forecasted this week.”
Contact has also recently purchased gas from Methanex so it could keep the Taranaki Combined Cycle gas station operating at full capacity through to the end of the year.
The hydro lakes have been under the microscope after Transpower put forward a proposal allowing generators to access “contingency storage” – which is stored hydro that is only made available for generation at specific times to mitigate the risk of shortage – much earlier than normally allowed.
The proposal will come into effect on September 1, but generators were still unsure whether they would access the contingency storage.
Meridian general manager wholesale Chris Ewers said it welcomed Transpower’s decision to remove potential barriers to generators’ access to contingent storage in certain hydro lakes, including Lake Pūkaki, but said it was increasingly unlikely this would be needed.
“Spring is typically a time of higher winds for New Zealand.
“Meridian has six wind farms that are regularly providing 25% – and occasionally 45% – of our total electricity generation.
“This, combined with rain in the Waiau catchment where we have Manapôuri Power Station, will help us conserve water in Lake Pukaki and build storage for next winter.”
Several major electricity users, including Fonterra, Woolworths, Oceania Gold and Rio Tinto, have called on Transpower to kick-start an energy conservation campaign.
Mr Ewers said such demands were “very premature” and a matter for Transpower to consider.
