Manapouri Power Traditional Geocache

Manapōuri Power Station is an underground hydroelectric power station on the western arm of Lake Manapouri in Fiordland National Park.

At 850 MW installed capacity (although limited to 800 MW due to resource consent limits), it is the largest hydroelectric power station in New Zealand, and the second largest power station in New Zealand. The station is noted for the controversy and environmental protests by the Save Manapouri Campaign against the raising the level of Lake Manapouri to increase the station's head, which galvanised New Zealanders and were one of the foundations of the New Zealand environmental movement.

Completed in 1971, Manapouri was built to supply electricity to the Tiwai Point aluminium smelter near Bluff, some 160 km (99 mi) to the southeast. Later, it was also connected into the South Island transmission network. The station utilises the 230-metre (750 ft) drop between the western arm of Lake Manapouri and the Deep Cove branch of the Doubtful Sound 10 km (6.2 mi) away to generate electricity. The construction of the station required the excavation of almost 1.4 million tonnes of hard rock to build the machine hall and a 10 km tailrace tunnel, with a second parallel tailrace tunnel completed in 2002 to increase the station's capacity.

The power station machine hall was excavated from solid granite rock 200 metres below the level of Lake Manapouri. Two tailrace tunnels take the water that passes through the power station to Deep Cove, a branch of Doubtful Sound, 10 kilometres (6.2 mi) away.

Access to the power station is via a two-kilometre vehicle-access tunnel which spirals down from the surface, or a lift that drops 193 metres (633 ft) down from the control room above the lake.

The original construction of the power station cost NZ$135.5 million (NZ$2.15 billion in 2013 dollars), involved almost 8 million man hours to construct, and claimed the lives of 16 workers.

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