Lake Pukaki

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Lake Pukaki
September 2005
Location	Mackenzie District, Canterbury Region, South Island
Coordinates	44°07′S 170°10′ECoordinates: 44°07′S 170°10′E
Primary inflows	Tasman River
Primary outflows	Pukaki River
Catchment area	1,413 km² ^[1]
Surface area	99 km² ^[1]
Average depth	47 m ^[1]
Max. depth	70 m ^[1]
Water volume	4.66 km³ ^[1]
Surface elevation	518.2 to 532 m ^[2]
Islands	Five Pound Note Island (now submerged)
References	^[1]^[2]

Lake Pukaki is a lake in New Zealand's South Island. It is the second-largest of three roughly parallel alpine lakes running north-south along the northern edge of the Mackenzie Basin (the others are Lakes Tekapo and Ohau). All three lakes were created by receding glaciers blocking their respective valleys with their terminal moraine (a moraine-dammed lake). The glacial feed to the lakes gives them a distinctive blue colour, created by glacial flour (extremely finely ground rock particles from the glaciers). It covers an area of 169 km², and the normal operating range lake level is 518.2 to 532 metres above sea level.^[2]

Lake Pukaki (bottom centre) and its neighbouring lakes are separated from the West Coast by the Southern Alps.

Lake Pukaki location

The lake is fed at its northern end by the braided Tasman River, which has its source in the Tasman and Hooker Glaciers, close to Aoraki/Mount Cook. Good views of the mountain, 70 kilometres to the north, can be had from the southern shore of the lake.

The lake's original outflow was at its southern end, into the Pukaki River. The lake is now, however, an upper part of the Waitaki hydroelectric scheme. As a result, the outflow has been dammed, and the water flows out through a canal linking it to a canal carrying water from Lake Ohau, from which it travels through through the Ohau A power tastion to Lake Ruataniwha. Pukaki is also fed by the waters of Lake Tekapo, which are diverted through a canal to a power station on Pukaki's eastern shore (Tekapo B station). The lake has been raised twice to increase storage capacity (9m in the 1940s, 37m in the 1970s), submerging Five Pound Note Island, which once appeared on New Zealand's five pound note. The current lake has an operating range of 13.8 m (the level within which it can be artificially raised or lowered), giving it an energy storage capacity of 1,595 GWh). Along with Lake Tekapo's 770 GWh storage, it provides over half New Zealand's hydroelectricity storage capacity.