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Wahapo Power Scheme

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Wahapo Hydroelectric Power Scheme makes use of the natural storage of Lake Wahapo, in the South Island of New Zealand. The Scheme has an average annual output of 15.3 GWh, and plays a vital role in ensuring reliable electricity supply to South Westland. We worked with the Department Of Conservation (DOC) and Fish and Game New Zealand to identify the best ways to encourage passage of trout, salmon and native fish species.

At a Glance

LOCATION: LAKE WAHAPO

Commissioned 1960

Max Capacity 3 MW

Annual output 15.3 GWh

Wahapo Station, formerly called Okarito Forks, was commissioned in 1960 with a generator set that was previously used in constructing the Homer Tunnel. Water was drawn from the natural Lake Wahapo, as is today. 

The Wahapo Scheme was redeveloped on the existing site in 1990, with maximum capacity boosted to the present day 3.1 MW. While the output is not major, Wahapo plays a vital role in ensuring reliable supply of electricity to South Westland, an area of extreme weather patterns. 

Environment and recreation 

Due to the volatile and flood-prone river environment, trout, salmon and native species can all have difficultly swimming past the weir at the outlet of Lake Wahapo, to the upstream spawning grounds. Perhaps once or twice a year, when spilling of water is restricted, salmon and trout can become trapped in the weir’s rocks. At such times, we contact West Coast Fish and Game to undertake recovery operations. 

After consulting at length with the Department of Conservation (DOC), we established a pipe-type pass, including rest areas, for native fish species. We are continuing discussions with Fish and Game NZ, with the shared goal of preventing trout and salmon becoming stranded below or in the weir. 

When Resource Consents for Wahapo Scheme were due to expire, we consulted widely with DOC, tangata whenua, and West Coast Fish and Game. West Coast Regional Council granted new consents in 2008.

Francis Turbine at Wahapo
Francis Turbine at Wahapo

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