New Zealand’s hydroelectric lake storage has dropped to less than two-thirds of the average, and rising winter demand is putting increasing pressure on supply. The fall in lake levels is also putting increasing pressure on the wholesale cost of electricity, which will eventually have to be passed on to domestic consumers if the trend continues.

The low levels of the storage lakes, which now have an average of 30% of their storage available, has raised concerns with the Energy Ministry, as there is a chance of some supply difficulties. In terms of storage capacity, Lake Wakatipu is only 13% full and Lake Wanaka 22% full. The country’s two main controlled storage reservoirs, Pukaki and Tekapo, are 51% and 46% full respectively. These two reservoirs provide 60% of the country’s hydroelectric storage.

The Waitaki lake system, which is headed by Pukaki and Tekapo, retains 71% of its average stored energy capacity but the Clutha system, fed by Wanaka, Wakatipu and Lake Hawea, has dropped to 33%.