South Island · New Zealand · Meridian/NZX
South Island
3,000 GWh
Well above average · 43% above average
vs 93-yr average
143%
In historical range
57%
Island
South Island
Last updated
2026-07-27
Where storage sits vs history
min2,100 GWh
93-yr avg4,300 GWh
max
Weekly readings
| Week | Stored (GWh) | % of 93-yr avg | Range 1927–2025 |
|---|---|---|---|
| 2026-07-27 | 3,000 | 143% | 1,300–4,300 |
Data source: Meridian Energy / NZX — Comparative Hydro Storage — weekly, energy basis (GWh), excludes contingent storage. New Zealand publishes no official national filling degree, so storage is shown against the 93-year average and the 1927–2025 range. Figures are read from the weekly chart and are approximate. Last reading: 2026-07-27.
About South Island
This is the aggregate hydro storage of the South Island — the combined controllable storage of its hydro lakes, reported as energy (GWh). Almost all of New Zealand’s controllable storage sits in the South Island, so the South Island figure closely tracks the national picture.
Frequently asked questions
How much water is stored in South Island right now?
As of 2026-07-27, South Island held about 3,000 GWh of stored energy — 43% above average (well above average) for the time of year, and roughly 56.7% of the way up its 1927–2025 range.
Why energy (GWh) and “% of average” instead of “% full”?
New Zealand publishes no official filling degree (percent full) for its hydro lakes, so there is no honest “100% full” to divide by. South Island’s storage is therefore reported in GWh and compared with the 93-year average and the historical range.
What does the South Island figure cover?
It is the aggregate hydro storage for the South Island — the sum of the island’s controllable storage lakes, reported as energy (GWh).