KEY POINTS:
Rain this week has provided some relief but the electricity industry remains concerned about lake levels and is asking the public to do its bit to save power.
Transpower said yesterday hydro lake levels were still a worry and the industry was continuing with contingency planning to ensure supply over winter.
Hydro lake levels were around 60 per cent of average storage, significantly lower than normal, because of the drought in both islands.
While there was heavy rain in the past couple of days, figures for inflows last week showed that they were only about half the average, and average lake level storage had reduced from 74 per cent last month.
Transpower chief executive Patrick Strange said the recent rain had bought the industry a little time.
"While the power system can manage with lower than average rainfall over the coming weeks, continuing very dry climatic conditions in the key South Island hydro catchments, or a loss of a major generating plant, while unlikely, would require further contingency measures to be implemented during May," he said.
Other factors that added to worries included the unexpected closure of the New Plymouth power station, dry summer conditions restricting output from the Huntly thermal power station, which led to more hydro powering the system, and the decommissioning of one of two systems operating the Cook Strait cable.
The industry was already taking measures to conserve water and North Island thermal production had been boosted and a greater amount of power sent south.
High spot prices would also aid conservation. "All generating companies are also ensuring their own generation plant is fully available where possible and there are no problems with thermal fuel supplies," Strange said.
If dry weather continued measures would escalate.
Generators and retailers were talking to larger customers about reducing their electricity usage if needed and planning had started for a public awareness campaign.
"Although this would be the final measure to be implemented and is some time away, it is important and prudent to have the plan in place so that it can be implemented quickly should it be needed."
The industry called on the public to be prudent and switch off unnecessary appliances or while not in use.
"We are not asking for consumers to go without electricity.
"They just need to be mindful of conserving electricity that is not being used."
Last month the National Party said power cuts may happen this winter but Energy Minister David Parker said the risk was less than 5 per cent.
The last time there were serious shortages was in 1992.
- NZPA
