Reservoir Watch

New Zealand generates most of its electricity from hydropower, and almost all of its controllable storage sits in a handful of large South Island lakes — Pūkaki and Tekapo on the Waitaki, Te Anau and Manapōuri in the south, Hāwea on the Clutha — plus Lake Taupō in the North Island. Because that storage is drawn on to keep the lights on, it is measured as energy (GWh), not water volume.

There is no official national filling degree (percent full), so the meaningful question is not “how full” but “how does storage compare with normal for the time of year”. As of 2026-09-07, national storage was 54% above average — well above average. Storage is typically drawn down through winter and refills with spring inflows; comparing the current figure with the 93-year average and the historical range shows whether the country is running wet or dry.