South Island hydro-electric storage lake levels are looking good as winter approaches, although hydro schemes in the North Island continue to be affected by dry weather.
Contact Energy Clutha generation manager Graham Quinn said significant and extended rainfall across the lower South Island recently had boosted the levels of hydro-electric storage lakes.
However, similar electricity schemes in the North Island are under pressure after an Indian summer, in which many regions have been affected by severe drought conditions.
The contrasting situations meant electricity suppliers had to perform a "balancing act", Mr Quinn said.
Electricity generated at South Island hydro-electric schemes was fed into the national grid "the instant it was made", Mr Quinn said.
Full hydro-electric lakes in the South would not translate into cheaper wholesale electricity prices for retail customers in the South Island, because the balancing act required power be shared around the country, he said.
Lakes Pukaki and Tekapo, the two storage lakes at the top of the Meridian Energy Waitaki system, are both close to full after about 500mm of rain fell at Mt Cook last week.
Between them, the lakes account for about 60% of New Zealand's hydro-electric storage.
Lake Tekapo was 97% full at 710.33m above sea level and Lake Pukaki was 98% full at 532.314m.
For this time of year, Tekapo's level is 130% of average and Pukaki's 120%.
