KEY POINTS:
Spot power prices continue to push up as southern hydro lake levels drop.
Hydro storage levels were 62 per cent of average storage on Sunday, down from 66 per cent a week earlier.
The daily average electricity spot market price at the North Island reference point of Haywards climbed to 30.37c per kilowatt hour, from 11.71c a month ago and 6.53c a year ago.
Figures from market operator M-Co show inflows dropping from 73 per cent of average last Monday to 50 per cent yesterday.
The forecast for the next few days is for some rain in the southern hydro catchment areas but Niwa and the MetService maintain that rainfall will be average or below average for the early part of winter.
In the next few days snow is also forecast which puts strain on the system in two ways.
The colder weather increases domestic demand and snow from now on typically doesn't melt and fill lakes until spring.
Transpower's chief executive Patrick Strange said there was a chance rain this week would help replenish hydro lakes.
"If we do not get that rain we're probably going to have a dry period after that and see lakes fall.
"It's a time to be cautious."
A few days' rain earlier this month had "bought" a week of breathing space, Strange said. "If we don't have rain by the end of the month we're going to have to look at it very closely again."
Prices would continue to stay high, thereby forcing some big users who could cut use to do so.
Planning is also underway for a conservation campaign but this would not be implemented unless absolutely necessary.
If the public perceived a campaign was being implemented for the wrong reasons they would lose faith, he said.
"You cannot cry wolf if the wolf is not around."
The Government's emergency reserve plant at Whirinaki, built after the 2003 dry year, is now running regularly.
It kicks in when the the wholesale price tops $200 a megawatt/hour.
Strange said other generators' thermal plant was operating well but was taken out of commission at times for routine maintenance.
Transpower yesterday confirmed the two successful providers who will act as aggregators for the Demand Side Participation trial this winter in the Upper South Island.
The providers are Energy Response, an independent aggregator, and TrustPower. The trial will begin on June 1 and finish at the end of August and is not related to the low lake situation, said a spokesperson.
