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About our snow storage calculations

During spring and summer, snow in the Waitaki catchment melts, flowing into rivers and lakes and contributing to hydro inflows and storage. Snow melt is estimated to contribute approximately half of the inflows to the Waitaki catchment over the summer period although this figure varies1.

Meridian collects information on the amount of water stored as snow so we can estimate its impact on inflows.

Meridian makes no representation as to the amount, timing and location of any such inflows through the publication of this information.

Calculating snow water equivalent (SWE) is complex and resulting estimates (and their relationship to lake inflows) have a high degree of uncertainty. Reliance should not be placed on the accuracy or completeness of the estimates provided and you should not use this information for investment or trading purposes. Meridian publishes a monthly operating report on the NZX and ASX outlining the current hydro storage position each month.

Seasonal snow storage in Waitaki catchment as at 6 July 2024

Snow storage relative to the time of year
Current 522 GWh
Mean 784 GWh
Percentage 66%
Minimum 511 GWh
Maximum 1219 GWh


This chart is updated weekly. You should be aware that specific rain events may significantly impact SWE and increase that degree of uncertainty. The chart shows an estimation of the amount of snow stored in the Waitaki catchment relative to the long term distribution. The black line shows the estimated snow storage. The coloured areas show the long term variability (mean, min, max, 25th%ile and 75th%iles). 

1. McKerchar, A. I., C. P. Pearson, and B. B. Fitzharris. 1998. Dependency of Summer Lake Inflows and Precipitation on Spring SOI. Journal of Hydrology 205:66-80.