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Meridian Energy water level guage.
Lake Tekapo.
Hydroelectric generation contributes around 60% of New Zealand's total electricity supply, with many generators of widely varying sizes distributed throughout the country.
Inflows (rainfall and snowmelt) can be stored in hydro lakes until needed. The most important are Lakes Tekapo, Pukaki, Hawea, Manapouri, Te Anau, and Taupo. The lakes have quite limited operating ranges – for technical and resource consent reasons, each lake's level cannot be lowered below a certain point. It is not possible to completely 'empty' a hydro lake! In the absence of inflows, the lakes can only hold enough water for a few weeks of winter energy demand. Original public domain image from Flickr
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