Manapouri Power Station

Manapouri Power Station is an underground hydroelectric power station on the western arm of Lake Manapouri in Fiordland National Park, in the South Island of New Zealand. 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 160km to the southeast. Later, it was also connected into the South Island transmission network. The station utilises the 230m drop between the western arm of Lake Manapouri and the Deep Cove branch of the Doubtful Sound 10km 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.