OPUS International prepared a report "Lake level history" for the Electricity Commission which provides a brief history of the fluctuations in the levels of the major lakes used for hydropower generation in New Zealand.

The lakes covered in the report are: Ohau, Tekapo, Pukaki, Te Anau, Manapouri, Hawea, Wanaka, Wakatipu, Taupo and Waikaremoana. The report describes the recording equipment used to measure levels and provides some guidance on how to interpret the data.

The report is accompanied by a dataset which includes average daily lake levels in metres above sea level (masl) for the entire length of record available. These data have been obtained from the Power Archive, which is maintained by OPUS International under contract to the various power generation companies.