But national grid operator Transpower says people do not need to worry just yet.
Scott Aronsen, an electrician and Mackenzie district councillor, said Lake Pukaki had been steadily dropping for months and was not far away from the lowest level — 518m above sea level — allowed.
"We could be up a creek without a paddle.
"It’s like playing Russian roulette with what we are doing at the moment.
"We need to start power conservation."
Transpower confirmed this week it was proposing to allow 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.
Transpower executive general manager operations Chantelle Bramley said although the dry conditions around the country had prompted a range of industry actions, they were not asking consumers to conserve energy at this stage.
"We expect hydro storage levels to increase in spring as rain falls, which will mitigate the situation.
"But even in a worst-case scenario of hydro inflows due to insufficient rain, we are not forecast to reach the point of launching an Official Conservation Campaign until early January."
Dry year events had happened many times, but this year was particularly bad, Mr Aronsen said.
"If we get near to 518m then we are getting into a position where we have not been very often.
"There has been a contingency they can be able to go down to 513m in extreme situations but the concern around that is how far can you go?
"Will the lake ever be able to get back to what it once was if you go down that far?
"Will we get enough flows, even in spring, to get it back to normal?
"We haven’t had a decent rainfall for months now.
"I know spring is the rainy season, but are we going to get enough rain to get the lake back to full or near full."
A Meridian Energy spokesman said it was not time for drastic action from consumers yet.
"We’re not yet at the stage of needing people to conserve power, and we definitely don’t want to panic anyone.
"At the moment, security of supply is key, and we’re trying to be as transparent as possible about everything being done to manage the situation."
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.
Lakes under the microscope in the South include Tekapo, Pūkaki, Hāwea, Te Anau and Manapouri.
National Institute for Water and Atmospheric Research climate scientist Ben Noll said rain in the hydro lakes catchments had been "about 60% of average" for the winter.
"That means in order to bring the rainfall up to normal, we would need several sustained events over late August and early September.
"This would need to bring hundreds of millimetres of rain, and it would need to be in the right areas.
"We’re really at the stage where that forecast rain needs to happen."
Guardians of Lake Hāwea chairman Geoff Kernick said while the lake was lower than normal, the group would not want Transpower to grant permission to make it even lower.
"That’s out of our hands. But in the past when it’s been low, it has caused several problems.
"The most noticeable is the dispersion of silt which carries down to the township, which is never pleasant.
"But it would also affect the amenity of the lake, and make it very difficult to return to normal operations quickly."
Mr Aronsen, who keeps a daily eye on the lakes, said nearby Tekapo had been drained by operator Genesis for most of the year and led to canals running low.
Snow levels were also not great and though they would melt in spring and summer, much of the water would simply soak straight into the ground.
A graph from Meridian Energy showed snow storage levels were the worst they had been since recording started in 1994.
The decarbonising of the economy and the move away from fossil fuels had only led to more need for renewable electricity.
But it would take years to get these schemes under way and built and many were simply too hard to get across the line.
Many Twizel people were talking about the lack of water in the lakes and the need to conserve water and power.
"Central government need to start a campaign to conserve power.
"They need to start now.
"Historically we get most of our rain in the spring but will we get enough? We need a lot."
