The National Institute of Water and Atmospheric Research says heavy rain brought by last week's storms has almost filled Lake Taupo to capacity, but has made little difference to the South Island's main hydro lakes.
Across the country, hydro lake levels are at 72% of their average level for August.
Transpower chief executive Patrick Strange says the rain bypassed the key South Island lakes. Dr Strange says the Clutha, Waitaki, Manapouri and Te Anau systems did not receive any of the recent rain.
NIWA says it is not too concerned about water levels in the South Island hydro lakes, as winter is coming to an end.